The effect of rheumatoid arthritis on the anatomy of the female cervical spine: a radiological study.

The effect of rheumatoid arthritis on the anatomy of the cervical spine has not been clearly documented. We studied 129 female patients, 90 with rheumatoid arthritis and 39 with other pathologies (the control group). There were 21 patients in the control group with a diagnosis of cervical spondylotic myelopathy, and 18 with ossification of the posterior longitudinal ligament. All had plain lateral radiographs taken of the cervical spine as well as a reconstructed CT scan. The axial diameter of the width of the pedicle, the thickness of the lateral mass, the height of the isthmus and internal height were measured. The transverse diameter of the transverse foramen (d1) and that of the spinal canal (d2) were measured, and the ratio d1/d2 calculated. The width of the pedicles and the thickness of the lateral masses were significantly less in patients with rheumatoid arthritis than in those with other pathologies. The area of the transverse foramina in patients with rheumatoid arthritis was significantly greater than that in the other patients. The ratio of d1 to d2 was not significantly different. A high-riding vertebral artery was noted in 33.9% of the patients with rheumatoid arthritis and in 7.7% of those with other pathologies. This difference was statistically significant. In the rheumatoid group there was a significant correlation between isthmus height and vertical subluxation and between internal height and vertical subluxation.

The Journal of Bone and Joint Surgery. British Volume


Optimal increase in bone mass by continuous local infusion of alendronate during distraction osteogenesis in rabbits

Several methods have been used to increase bone mass in distraction osteogenesis. Since bone resorption as well as regeneration is stimulated in the distracted segment, bisphosphonate can be a beneficial agent for distraction osteogenesis. Here, we examined the effects of bisphosphonate injected continuously into the regenerate on bone volume, and architectural and mechanical properties of distraction osteogenesis. The left tibia of Japanese White rabbits (n=66) was subjected to slow distraction using an external fixator. At the beginning of the consolidation phase, alendronate (7 microg/kg/day) was infused directly into the lengthened segment for 14 days using an osmotic pump. Control rabbits were infused with phosphate buffered saline (PBS). The tibiae were monitored weekly by soft X-ray and dual-energy X-ray absorptiometry (DXA). The animals were sacrificed at 4, 6, and 8 weeks after operation to examine bone mineral density (BMD) and cortical bone thickness (CBT) by peripheral quantitative computerized tomography (pQCT), while the mechanical property of the lengthened tibia was measured by three-point bending test. In PBS-infused control animals, bone mineral content around the lengthened segment began to decrease after the first week of consolidation phase, forming a tubular bone structure with thin cortex. Infusion of alendronate increased peak bone mineral content around the lengthened segment. At the end of the experiment, volumetric BMD, CBT and mechanical strength of the lengthened segment of the treatment group were approximately twice those of the control animals. Alendronate infused in this manner significantly prevented the osteopenia that critically began early in the consolidation phase, though the dose used in this study was relatively low and no adverse events were noted.


Minimally invasive technique for direct repair of pars interarticularis defects in adults using a percutaneous pedicle screw and hook-rod system.

In this report, the authors described a new minimally invasive technique to repair pars interarticularis defects in adults. The well-established technique using the pedicle screw (PS) and hook-rod system was modified. First, bilateral PSs were inserted percutaneuosly using the Sextant system. Then, through a small skin incision (3-4 cm), an illuminated tubular retractor (Quadrant system; Medtronic Sofamore Danek) was inserted into the pars defect. When this system is used, it is not necessary to detach all the back muscles to access the lytic part. The bursa and fibrocartilaginous mass near the defects were removed. After decortication of the pseudarthrosis at the spondylolytic level, bone grafts were implanted. Finally, the hook part of a hook-rod system was attached to the lamina and the rod was secured at the tulip head of the PSs. The authors performed this procedure in 2 adult patients, 32 and 24 years of age. Immediately after surgery both patients' low-back pain disappeared, and by 3 months postoperatively both had returned to their original work or sports activities.


Intramedullary schwannoma with calcification of the epiconus.

There have been few reports on intramedullary ancient schwannoma. Schwann cells are generally present in the nerve root, not in the spinal cord. Thus, intramedullary schwannomas are rare, and in most cases there is cyst formation without calcification. To report a patient with intramedullary ancient schwannoma at the epiconus together with a review of the previously published cases. Case report. A 78-year-old woman. Retrospective case review. DESCRIPTION OF THE CASE: A 78-year-old woman had presented with severe weakness of the lower extremities, increased patellar reflex, and sensory disturbance of the entire lower extremities. Magnetic resonance imaging showed a tumorous mass in the intramedullary region of epiconus at T11-L1, and computed tomography revealed calcification in the tumor. She underwent total resection of the tumor. Histopathological findings were consistent with the diagnosis of ancient schwannoma. After the operation, although lower extremities weakness and sensory disturbance deteriorated transiently, lower leg pain disappeared. At the final follow-up of 10 months after the operation, lower leg pain did not relapse. We reported a rare case presenting epiconus syndrome due to intramedullary ancient schwannoma, which should be considered for the differential diagnosis of a tumor that shows calcification.


Fresh stress fractures of lumbar pedicles in an adolescent male ballet dancer: case report and literature review.

Stress fracture in the pars interarticularis is a common cause of low back pain in young athletes. Pedicle stress fractures have also been reported in adolescent sport players, and most of them were associated with contralateral spondylolysis. Only a few cases with bilateral pedicle stress fractures have been reported. We report a 14-year-old ballet dancer with fresh bilateral pedicle fractures treated conservatively, together with a review of the literature.

Archives of Orthopaedic and Trauma Surgery


Conservative treatment of lumbar spondylolysis in childhood and adolescence: the radiological signs which predict healing.

It has been noted that bony union of a pars defect can be achieved in children if they wear a trunk brace. Our aim was to evaluate how the stage of the defect on CT and the presence or absence of high signal change in the adjacent pedicle on T2-weighted MRI were related to bony healing. We treated 23 children conservatively for at least three months. There were 19 boys and four girls with a mean age of 13.5 years (7 to 17). They were asked to refrain from sporting activity and to wear a Damen soft thoracolumbosacral type brace. There were 41 pars defects in 23 patients. These were classified as an early, progressive or terminal stage on CT. The early-stage lesions had a hairline crack in the pars interarticularis, which became a gap in the progressive stage. A terminal-stage defect was equivalent to a pseudarthrosis. On the T2-weighted MR scan the presence or absence of high signal change in the adjacent pedicle was assessed and on this basis the defects were divided into high signal change-positive or -negative. Healing of the defect was assessed by CT. In all, 13 (87%) of the 15 early defects healed. Of 19 progressive defects, only six (32%) healed. None of the seven terminal defects healed. Of the 26 high signal change-positive defects 20 (77%) healed after conservative treatment whereas none of the high signal change-negative defects did so. We concluded that an early-stage defect on CT and high signal change in the adjacent pedicle on a T2-weighted MR scan are useful predictors of bony healing of a pars defect in children after conservative treatment.


Cervical and upper thoracic screwing for spinal fusion: strategy for its safe insertion to avoid major complications.

There are several screwing techniques to attain cervical fusion such as pedicle screw, lateral mass screw, facet screw, transarticular and laminar screw. Each screwing technique has advantages and disadvantages. In this study, we introduce our strategy for safe screwing and its clinical results. Our strategy is as follows: lateral mass screw for C1, 3, 4, 5, 6 and pedicle screw for C2, 7, and thoracic level. When the C2 pedicle is thinner than 3.5 mm, we use C2 laminar screws. We do not use Magerl transarticular screw or facet screw; 146 screws were inserted in 17 patients. There were no major complications such as spinal cord and nerve root injury. We did not observe vertebral arterial injury either. Of the 146 screws, 141 (97.0%) were accurately inserted. As for lateral mass screwing by Roy-Camille's technique and C2 laminar screwing, all screws were inserted in the appropriate site (100%) without any complications. Five pedicle screws were misplaced. Of the 57 pedicle screws, 5 showed a minor tear of the wall at C7, Th1 and Th3, the success rate for all pedicle screws was 91%. All showed solid fusion. For cervical screwing the most important aspect should be safety to avoid severe morbidity. Our strategy, which consists in the combined use of pedicle, lateral mass and laminar screwing, is safe and reliable.


Cervical spondylolysis in a judo player. A case report and biomechanical analysis.

A case report and a biomechanical study using a finite element method. To report a case with the cervical spondylolysis and to understand the biomechanics of the cervical spine with spondylolysis at C6. Cervical spondylolysis, although not a common spinal disorder, can occur in athletes. Presently, the exact pathology, natural history and biomechanics are not known. Thus, treatment strategies for this disorder in athletes are in controversy. To treat and/or advise patients with cervical spondylolysis, the cervical spine biomechanics regarding this disorder should be understood. A case of a 12-year-old male judo player is presented. The patient presented with occipital and upper neck pain. Plain radiographs, reconstructed CT scan and MRIs of this patient were reviewed. Biomechanically, stress distributions were analyzed in response to 73.6 N axial compression and 1.5-Nm moment in flexion, extension, lateral bending, and axial rotation using a FE model of the intact ligamentous C3 to C7 segment. Bilateral spondylolysis was created in the model at C6. The stress results from the bilateral defect model were compared to the intact model predictions. Plain radiographs showed bilateral C6 spondylolysis, and grade I spondylolisthesis. MRI showed mild disc degeneration at C6/7. With conservative treatment, the symptoms disappeared. In the spondylolysis model, the maximum Von Mises Stresses at C6/7 increased in all cervical spine motions, as compared to the intact case. Specifically, in axial rotation, the stress increase was 3.7-fold as compared to the intact model. The range of motion at C6/7 increased in the spondylolysis model as well. Again, during axial rotation, the increase in motion was 2.3-fold when compared to the intact model. Cervical spondylolysis can cause biomechanical alterations, especially in axial rotation, leading to increased disc stresses and range of motion. The increased stresses in the disc and the hypermobility would be a dangerous condition for athletes participating in contact sports such as judo. Thus, we recommended that judo players with cervical spondylolysis should change to non-contact sports, such as jogging.


Newly occurred L4 spondylolysis in the lumbar spine with pre-existence L5 spondylolysis among sports players: case reports and biomechanical analysis.

STUDY DESIGN: Case series and a biomechanical study using a finite element (FE) analysis. OBJECTIVES: To report three cases with multi-level spondylolysis and to understand the mechanism biomechanically. BACKGROUND: Multi-level spondylolysis is a very rare condition. There have been few reports in the literature on multi-level spondylolysis among sports players. METHODS: We reviewed three cases of the condition, clinically. These patients were very active young sports players and had newly developed fresh L4 spondylolysis and pre-existing L5 terminal stage spondylolysis. Thus, we assumed that L5 spondylolysis may have increased the pars stress at the cranial adjacent levels, leading to newly developed spondylolysis at these levels. Biomechanically, we investigated pars stress at L4 with or without spondylolysis at L5 using the finite element technique. RESULTS: L4 pars stress decreased in the presence of L5 spondylolysis, which does not support our first hypothesis. CONCLUSIONS: It seems that multi-level spondylolysis may occur due to genetic and not biomechanical reasons.


Pseudoaneurysm of the thoracoabdominal aorta caused by the severe migration of an anterior spinal device. A case report.

Case report. To describe the case of pseudoaneurysm of the thoracoabdominal aorta caused by the severe migration of an anterior spinal device 5 years after surgery. Case report. A 70-year-old woman was referred to us because of migrated anterior spinal devices and a pseudoaneurysm of the thoracoabdominal aorta. This patient had undergone anterior corpectomy and spinal fusion from Th12 to L2 because of delayed palsy after a burst fracture using a smooth rod Kaneda device (SRK) with bioactive ceramic (apatite-wollastonite containing glass ceramic) at a local hospital. She had persistent low back pain after the surgery. Five years after the initial surgery, the patient was referred to us because of increasing of her low back pain and the migrated SRK devices shown on plain X-ray films. An enhanced computed tomography scan taken in our hospital clearly showed a pseudoaneurysm of the thoracoabdominal aorta surrounding the SRK devices. The pseudoaneurysm was resected, the aortic defect was repaired with an artificial patch, and the migrated SRK devices were removed. The pseudoaneurysm of the aorta can occur secondary to a migrated anterior spinal fixation device and can be successfully treated by revision anterior surgery with vascular repair and implant removal.


Os odontoideum in achondroplasia: a case report.

The neurological complication in achondroplasia has been focused on the foramen magnum stenosis. We report the combination of os odontoideum in a patient with achondroplasia.

Journal of Pediatric Orthopaedics. Part B


Minimally invasive excision of lumbar epidural lipomatosis using a spinal endoscope.

In this report, we describe the case of a patient with a long-term radiculopathy due to epidural lipomatosis at the L3-4 intervertebral disc level. The fatty tissue was located on the dorsal side of the dural sac in the spinal canal and compressed the dural sac. The fatty tissue was removed endoscopically. After surgery, the symptoms disappeared, and neurological deficits normalized. We would like to state that epidural lipomatosis is a good candidate for minimally invasive endoscopic surgery because of its anatomic location.


Myelopathy in a 6-year-old girl caused by neurofibromatosis Type 1: a case report

Even when there is radiological evidence of spinal involvement, young patients with neurofibromatosis Type 1 (NF-1) seldom have symptoms. We report the case of a child who developed rapidly progressive myelopathy. To describe a technique used to prevent postoperative spinal deformity and instability, after removal of a dumbbell-shaped tumor in a 6-year-old child. Case report. A 6-year-old female. Retrospective case review. The patient underwent a resection of the cervical dumbbell tumor using an osteoplastic laminectomy technique to prevent postoperative spinal deformity. At 2-year follow-up, there was no clinical or radiographic evidence of complications or spinal kyphotic deformity. The case of a 6-year-old girl with cervical myelopathy caused by NF-1 was reported. The tumor was removed after osteoplastic laminectomy, which could prevent postoperative kyphotic deformity.


Continuous local infusion of fibroblast growth factor-2 enhances consolidation of the bone segment lengthened by distraction osteogenesis in rabbit experiment.

Experimental tibial lengthening was achieved in 61 rabbits to examine the effect of continuous local infusion of recombinant human fibroblast growth factor-2 (rhFGF-2) on bone healing of the lengthened segment. The tibial diaphysis was separated by osteotomy and was subjected to slow progressive distraction (rate: 0.35 mm/12 h) using a monolateral external fixator. There were a lag phase for 1 week, a distraction phase for 2 weeks, and a consolidation phase for 5 weeks in this experiment. At various stages of distraction, rhFGF-2 was infused continuously for 2 weeks into the lengthened segment (rate: 14.28 microg/60 microl/day) using an osmotic pump implanted under the skin. Bone healing was significantly accelerated when rhFGF-2 was infused in the beginning of consolidation phase, but not in the distraction phase or in the lag phase. Infusion of normal saline (N/S) using the same osmotic pump had no effect. Dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computerized tomography (pQCT) studies demonstrated that rhFGF-2-treated tibia had increased bone mineral density (BMD), bone mineral content (BMC) and cortical bone thickness (CBT) when compared with N/S-treated tibia. Three-point bending test demonstrated that rhFGF-2-treated bone had significantly stronger mechanical properties than N/S-treated bone. Finally, distribution of the infused materials was checked by using Indian ink or radio-opaque. The dyes distributed widely but exclusively in the lengthened segment. Based on these results, we conclude that direct delivery of rhFGF-2 into the lengthened segment can shorten the consolidation phase of limb lengthening and the method is applicable to the clinical treatment.


Radiological features of lumbar spinal lesions in patients with rheumatoid arthritis with special reference to the changes around intervertebral discs.

Compared with the cervical spine, little attention has been paid to rheumatoid arthritis (RA)-related lumbar disorders. Only a few articles have described the status of the lumbar spine affected by RA based on plain X-ray films and magnetic resonance imaging (MRI). To describe the features and prevalence of radiological changes of the lumbar spine of patients with RA and to clarify the correlations of such features with disease activity. Transverse radiological study. We radiographically examined 104 patients with RA whose age ranged from 21 to 78 years (mean, 51.0). In each, the duration of RA exceeded 10 years (mean, 17.7 years). Clinical outcomes included Ochi's classification, Lansbury index, C-reactive protein (CRP) (mg/dL), rheumatoid factor (RF) (U/mL), and platelet (count/mm). Radiological outcomes included radiography and MRI. One hundred four RA patients were included in this study regardless of the presence/absence of low back pain. We examined discs from L1-2 to L5-S, including endplates, in each patient on plain X-ray films and magnetic resonance images and used a comprehensive grading system to evaluate each feature of the lumbar spine affected by RA based on the present findings and published reports. The correlations of these radiological features with RA activity and Ochi's classification were examined. To quantify disease activity, we determined the Lansbury index, serum CRP (mg/dL), RF (U/mL), and platelet count (count/mm) at the time of radiological examinations. Of the 104 patients, 47 (45.2%) exhibited a lumbar lesion. There were two types of lumbar disc lesions related to RA: disc narrowing and disc ballooning. The Lansbury index of patients with the most severe lesions was significantly higher than that of patients with less severe lesions (p<.01). The frequency of lumbar involvement also increased as the number of affected peripheral joints increased, and Ochi's classification appeared to be useful in predicting the occurrence of lumbar lesions. Of 104 patients, 47 (45.2%) exhibited abnormalities on X-ray films and MRI. There were two types of disorders, disc narrowing and disc ballooning. Both the Lansbury index and Ochi's classification reflected the severity of lumbar lesions in RA patients.


Vertebral rounding deformity in pediatric spondylolisthesis occurs due to deficient of endochondral ossification of the growth plate: radiological, histological and immunohistochemical analysis of a rat spondylolisthesis model.

A study using rat spondylolisthesis models. To clarify pathomechanism of vertebral rounding deformity in pediatric spondylolisthesis. For high-grade slippage, rounding of sacrum surface associated with L5 spondylolisthesis is reported to be the most responsible risk factor. However, the exact pathomechanism of the rounding deformity is yet to be clarified. Spondylolisthesis rat model (4-week-old) was used. Radiographs were taken weekly for 5 weeks after the surgery. The lumbar spines were harvested for histology. Hematoxylin and eosin, alcian blue staining, and tartrate-resistant acid phosphatase staining were used. Immunohistochemically, the growth plate cartilage was studied for type II and X collagen. A modified bone histomorphometric analysis was also performed. Radiographs showed slippage 1 week after surgery. Rounding deformity was obvious 2 weeks after surgery. The rounding deformity progressed with time. Three weeks after surgery, the specific columns of growth plate were unclear at the anterior corner, which corresponded to the rounding surface observed on radiographs. Instead, a huge mass of cartilage was observed at that site. Tartrate-resistant acid phosphatase-positive cells were observed in the vicinity of the growth plate except in relation with the anterior corner. The growth plate and cartilage mass at the anterior corner stained positive for type II collagen. Chondrocytes in the hypertrophied layer stained positively for type X collagen; however, staining was faint at the anterior corner. The results suggested that the chondrocytes at the anterior did not form, morphologically and functionally, the normal growth plate. From histomorphometrical analysis, the normal posterior growth plate made endochondral bone growth in 510 +/- 20 microm for a week, whereas the anterior corner in 200 +/- 15 microm. Deficient endochondral ossification of the growth plate in the anterior upper corner of the vertebra could be the pathomechanism of the rounding deformity of the sacrum.


Pathomechanism of loss of elasticity and hypertrophy of lumbar ligamentum flavum in elderly patients with lumbar spinal canal stenosis.

A histologic, biologic, and immunohistochemical assessment using human samples of lumbar ligamentum flavum. To clarify the pathomechanism of loss of elasticity and hypertrophy of the lumbar ligamentum flavum (LF) in the elderly population. The most common spinal disorder in elderly patients is lumbar spinal canal stenosis, causing low back and leg pain, and paresis. Canal narrowing, in part, results from hypertrophy of the LF. Although histologic and biologic literature on this topic is available, the pathomechanism of loss of elasticity and hypertrophy of the LF is still unknown. One fetus, 5 young, and 5 elderly LF were obtained for histologic study. Hematoxylin and eosin, Alcian blue, Masson Trichrome, and Elastica Van Gieson stains were performed for each LF. Nine LF were collected and were used for biologic study of real time RT-PCR to quantitatively measure mRNA expression of Type I collagen and elastin in each LF. In the LF of the fetus, elastic fibers accounted for about 75% of the entire area. In the dural aspect of the LF in the young and elderly group, the ratio was also around 75%; however, the ratio of the dorsal aspect decreased with age. Almost half of the area showing loss of elastic fibers was shown to be converted to cartilaginous tissue producing Type II collagen and proteoglycan by Alcian blue and Type II collagen immunohistochemistry. The area, which did not stain black with EV nor blue with AB stain, was positively stained blue with T stain, indicating scarring. The area of the normal dural layer was 18.0 +/- 2.3 and 33.8 +/- 4.3 (mm2), for young and elderly group, respectively. Accordingly, it was 3.2 +/- 0.8 and 18.0 +/- 10.2 (mm2), for the dorsal abnormal layer. Elastin mRNA showed a relatively strong correlation (r = 0.44) with age; however, the slope was very gentle. Type I collagen mRNA showed a very strong correlation (r = 0.80) with age. The slope was steeper, and the value reached at 1000% (10-fold) around 65 years old when compared with the LF from younger patient. Elastin mRNA showed a weak correlation (r = 0.36) with thickness, and the slope was gentle. Type I collagen mRNA showed relatively strong correlation (r = 0.52) with thickness. The slope was steeper, and the line reached at 1000% (10-fold) around 6.5 (mm) when compared with a thin LF. Decreased elasticity of LF in the elderly is due to the loss of elastic fibers and a concomitant increase of collagenous fibers in the dorsal aspect. LF hypertrophy could be due to the thickening of the normal elastic layer as well as of the abnormal collagenous layer.


Intraneural heterotopic ossification of a digital nerve.

The Journal of Hand Surgery, European Volume


Callus formation during healing of the repaired tendon-bone junction. A rat experimental model.

This study was undertaken to elucidate the mechanism of biological repair at the tendon-bone junction in a rat model. The stump of the toe flexor tendon was sutured to a drilled hole in the tibia (tendon suture group, n = 23) to investigate healing of the tendon-bone junction both radiologically and histologically. Radiological and histological findings were compared with those observed in a sham control group where the bone alone was drilled (n = 19). The biomechanical strength of the repaired junction was confirmed by pull-out testing six weeks after surgery in four rats in the tendon suture group. Callus formation was observed at the site of repair in the tendon suture group, whereas in the sham group callus formation was minimal. During the pull-out test, the repaired tendon-bone junction did not fail because the musculotendinous junction always disrupted first. In order to understand the factors that influenced callus formation at the site of repair, four further groups were evaluated. The nature of the sutured tendon itself was investigated by analysing healing of a tendon stump after necrosis had been induced with liquid nitrogen in 16 cases. A proximal suture group (n = 16) and a partial tenotomy group (n = 16) were prepared to investigate the effects of biomechanical loading on the site of repair. Finally, a group where the periosteum had been excised at the site of repair (n = 16) was examined to study the role of the periosteum. These four groups showed less callus formation radiologically and histologically than did the tendon suture group. In conclusion, the sutured tendon-bone junction healed and achieved mechanical strength at six weeks after suturing, showing good local callus formation. The viability of the tendon stump, mechanical loading and intact periosteum were all found to be important factors for better callus formation at a repaired tendon-bone junction.

The Journal of Bone and Joint Surgery. British Volume


Locking of the metacarpophalangeal joint as a result of the shape of the metacarpal head in achondroplasia.

A 21 year-old woman with achondroplasia exhibited locking of the metacarpophalangeal joint of the right index finger which required surgery to release the joint. Locking was confirmed to be due to entrapment of the fan-like part of the radial collateral ligament on a metacarpal head prominence arising from epiphysial thickening.


Lumbar radiculopathy caused by extradural rheumatoid nodules. A case report.

The authors report on a 51-year-old woman with a 9-year history of rheumatoid arthritis (RA) who presented with symptomatic rheumatoid nodules in the lumbar extradural region with compression on the L-5 nerve roots bilaterally. She had also suffered from dysesthesia in the right lower leg and intermittent claudication. Magnetic resonance imaging revealed masses compressing the dural sac, and on lumbar myelography and computed tomography myelography a filling defect at L4-5 was revealed, which was compressing the dural sac posterolaterally on both sides. The masses were surgically removed. On histological examination the typical characteristics of rheumatoid nodules were found. Soon after the operation all of the patient's symptoms disappeared. There have been few reports on extradural rheumatoid nodules. Patients with RA usually complain of articular symptoms, and in fact the patient in the present study had been referred to the authors' institution for total hip arthroplasty. However, various symptoms other than those arising from articular lesions were found clinically. The authors believe that if patients with RA are also examined for extraarticular lesions, it is likely that these will be more frequently detected.


Minimally invasive endoscopic removal of herniated nucleus pulposus that had migrated to the S1 nerve root foramen.

In this report, we described an adult case with a lumbar herniated nucleus pulposus that had migrated to the S1 nerve root foramen from L5-S1 disc space. Endoscopically, the migrated mass was successfully removed after laminectomy at the S1 with a small skin incision of 20 mm in length. Unlike the other levels, the intraforaminally migrated mass along the S1 root can be excised without any removal of the facet joints; therefore, additional spinal fusion is not necessary. Thus, an S1 foraminal migrated mass can be a good surgical candidate for minimally invasive endoscopic surgery.


Minimally invasive decompression for lumbar spinal canal stenosis in younger age patients could lead to higher stresses in remaining neural arch ? A Finite Element Investigation.

A young patient group with the symptoms of acquired spinal stenosis has been identified recently in the literature. The patients between 25-50 years of age were found to have signs of lumbar spinal stenosis because of degenerative spinal changes. Some of them were operated on using the same limited decompression approaches as the older patients. However, this group differs from the geriatric population due to the scarcity of remodeling degenerative signs at the spine. Therefore, the possible ligamentous laxity, facet joint degeneration or only the removal of some spinal structures could lead to the increased stresses in the remaining spinal arch and could have an unfavorable course of events after the procedure. A biomechanical study has been done using an experimentally validated finite element model (FEM) of the intact L3-S1 lumbar spine to elucidate the influence of the limited decompression on range of motion (ROM) and stress distribution on the neural arch in this patient group. We simulated unilateral laminotomy L4 and medial facetectomy L4-5, medial facetectomy L4-5 and lateral fenestration of L5 pars interarticularis, combined transarticular lateral and medial approach with partial facetectomy L4-5, "port-hole" decompression at the L4 level, and hemilaminectomy L4 with medial facetectomy L4-5. The ROM and maximum von Mises stresses were analyzed in flexion, extension, lateral bending, and axial rotation in response to a 10.6 Nm moment with 400 N axial compression. The data were compared with the intact spine and hemilaminectomy L4 with medial facetectomy L4-5 models. The investigation revealed almost the same ROM after simulation but a considerable increase in stresses at both the pars interarticularis and the inferior facet after limited decompressions, especially in extension and rotation to the contralateral side. Stresses at the contralateral L4 pedicle were highest after L4 hemilaminectomy and medial facetectomy L4-5. Due to the observed increases in stresses, the surgeon should be aware of the possibilities of stress-fractures in this patient group.


Minimally invasive technique for direct repair of the pars defects in young adults using a spinal endoscope. A technical note.

Pars defect (spondylolysis) of the lumbar spine can cause chronic low back pain, and it sometimes requires surgical intervention. Direct repair is selected for the surgery if young adult patients do not present significant disc degeneration and lumbar instability. In order to lessen damages of back muscles during surgery, we added the use of a spinal endoscope to the "Buck's screwing procedure" the direct repair. There are four steps in this procedure: 1) identification of the defect, 2) curettage (refresh) of the defect, 3) percutaneous insertion of the annulated screws and 4) cancellous bone grafting. All these steps can be done endoscopically. We treated 3 young adults--a baseball player, a professional cycle-racer and a sculptor--using this endoscopic procedure. There were no complications during or after the operation. Union was obtained in all defects within 3 months, and they returned to their previous activities within 6 months after the surgery.


Extension of contained rupture of an abdominal aortic aneurysm into a lumbar intervertebral disc. Case report.

Chronic contained rupture of an abdominal aortic aneurysm (AAA) is a rare event, making its diagnosis difficult. A delayed diagnosis and delayed surgical repair compromise the outcome. In this paper the authors report the case of a chronic contained rupture of an AAA causing spinal destruction, in which diagnosis was difficult because the lesion produced symptoms mimicking those of pyogenic spondylitis.


Biomechanical rationale for using peek spacers for lumbar interbody fusion - a finite element study.

To determine the effect of cage/spacer stiffness on the stresses in the bone graft and cage subsidence. To investigate the effect of cage stiffness on the biomechanics of the fused segment in the lumbar region using finite element analysis. There are a wide variety of cage/spacer designs available for lumbar interbody fusion surgery. These range from circular, tapered, rectangular with and without curvature, and were initially manufactured using titanium alloy. Recent advances in the medical implant industry have resulted in using medical grade polyetheretherketone (PEEK). The biomechanical advantages of using different cage material in terms of stability, subsidence, and stresses in bone graft are not fully understood. A previously validated 3-dimensional, nonlinear finite element model of an intact L3-L5 segment was modified to simulate posterior interbody fusion spacers made of PEEK ("E" = 3.6 GPa) and titanium ("E" = 110 GPa) at the L4/5 disc with posterior instrumentation. Bone graft ("E" = 12 GPa) packed between the spacers in the intervertebral space was also simulated. The posterior lumbar interbody fusion spacer with instrumentation and graft represent a simulation of the condition present immediately after surgery. The peak centroidal Von Mises stresses in the graft bone increased by at least 9-fold with PEEK spacers as compared to titanium spacer. The peak centroidal Von Mises stresses in the endplates increased by at least 2.4-fold with titanium spacers over the PEEK spacers. These stresses were concentrated at places where the spacer interfaced with the endplate. The stiffness of the spacer did not affect the relative motion (stability) across the instrumented (L4/5) segment. Spacers less stiff than the graft will: (1) provide stability similar to titanium cages in the presence of posterior instrumentation, (2) reduce the stresses in endplates adjacent to the spacers, and (3) increase the load transfer through the graft, as evident from the increase in stresses in graft.


Buck's Direct Repair of Lumbar Spondylolysis Restores Disc Stresses at the Involved and Adjacent Levels.

Lumbar spondylolysis was reported to cause disc degeneration at both caudal and cranial adjacent level. However, basic disc biomechanics in the spondylolytic spine is not fully understood. Purpose of this study was to analyze the disc stresses at cranial and caudal adjacent level of lumbar spondylolysis. Also, the biomechanical effects of Buck's technique on disc stresses at these two segments were evaluated. An experimentally validated three-dimensional non-linear finite element model of the intact ligamentous L3-S1 segment was used. Bilateral lumbar spondylolysis was simulated by creating bilateral pars defects with 1.0 mm gap at L5. Buck's direct repair model was simulated with 4.0 mm cannulated Titanium screws, placed bilaterally across the defect. Von Mises stresses in the annulus fibrosus and nucleus pulposus at L4/5 (cranial adjacent) and L5/S (caudal adjacent) disc levels were analyzed in flexion, extension, lateral bending and axial rotation in response to 400 N of axial compression and 10.6 Nm moment. The highest values were compared among the three models, intact, spondylolysis and Buck's technique. After spondylolysis occurred at L5, annulus fibrosus and nucleus pulposus stresses at L4/5 increased to 111% and 120%, respectively. After the Buck's technique it recovered to 102% and 105%, correspondingly. On the other hand, at L5/S, annulus fibrosus stress increased to 168%, and nucleus pulposus, 155%, which was much higher when compared to the stresses at L4/5. After the Buck's technique the stresses were decreased to 125% and 120%, correspondingly. During rotation motion, especially, the operation normalized the disc stress completely. Spondylolysis increases disc stresses at the affected as well as cranial adjacent level, and it may lead to disc degeneration at both levels. However, the increase in stresses is higher at the affected caudal level, when compared to the cranial level. Buck's technique may restore the disc stresses back to normal at both disc levels. Thus, this technique may be beneficial from a biomechanical perspective as well.


Biomechanics of two level Charite artificial disc placement in comparison to fusion plus single level disc placement combination

Biomechanical studies of artificial discs that quantify parameters such as load sharing and stresses have been reported in literature for single-level disc placements. However, literature on the effects of using the Charité artificial disc (ChD) at two levels (2LChD) as compared with one-level fusion (using a cage [CG] and a pedicle screw system) plus one-level artificial disc combination (CGChD) is sparse. To determine the effects of the 2LChD and CGChD across the implanted and adjacent segments. A finite element model of a L3-S1 segment was used to compare the biomechanical effects of the ChD placed at two lower levels (2LChD model) with L5-S1 fusion (using a CG and a pedicle screw system) plus L4-L5 level ChD placement combination (CGChD model). We used our recently published and experimentally validated L3-S1 finite element model for the present study. The intact model was subjected to 400 N axial compression and 10.6 Nm of flexion/extension moments. The experimental constructs described above were then subjected to 400 N axial compression and a moment that produced overall motion equal to the intact model predictions (hybrid testing protocol). Resultant motion, loads across facets, and other parameters were analyzed at the experimental and adjacent levels. In flexion, the bending moments for the CGChD and 2LChD models were 15.4 Nm (fusion effect) and 7.3 Nm (increase in flexibility effect), respectively in comparison to 10.6 Nm for the intact model. The corresponding values in the extension mode were 11.2 Nm and 7.2 Nm. The predicted flexion rotations across the L5-S1 segment for the CGChD decreased by 76% (fusion effect), and increased at the L4-L5 and the L3-L4 levels by 68.5% and 28%, respectively. In the extension mode, motion across the L5-S1 segment decreased by 96.4% whereas it increased 74.6% and 18.2% across the L4-L5 and L3-L4 levels, respectively. For the 2LChD model, the flexion rotation across the L5-S1 segment increased by 28.2%. The motions across the L4-L5 and L3-L4 segments decreased by 12% and 24%, respectively. In extension, the corresponding changes were 10% increase, 10% increase, and 21% decrease at the L5-S1, L4-L5, and L3-L4 levels, respectively. The facet loads were in line with the changes in motion, except for the 2LChD case. The changes at L3-L4 level for both of the cases were of similar magnitude (approximately 25%), although in the CGChD model it increased and in the 2LChD model it decreased. The changes in motion at the L4-L5 level were large for the CGChD model as compared with the 2LChD model predictions (approximately 70% increase vs. 10% increase). It is difficult to speculate if an increase in motion across a segment, as compared with the intact case, is more harmful than a decrease in motion.


Effect of lumbar interbody cage geometry on construct stability: a cadaveric study.

Biomechanical study to investigate three-dimensional motion behavior of cadaveric spines in various surgical simulations. To determine the effect of cage geometry on the construct stability. There is a wide variety of cage/spacer designs available for lumbar interbody fusion surgery. These range from circular, tapered, and rectangular with and without curvature. However, the effectiveness of cages with different designs and materials to stabilize a decompressed intervertebral space has not been fully studied. Six fresh ligamentous lumbar spine specimens (L1-S2) were subjected to pure moments in the six loading directions. The resulting spatial orientations of the vertebrae were recorded using Optotrak Motion Measurement System. Measurements were made sequentially for intact, bilateral spacer placements across L4-L5 using a posterior approach, supplemented with pedicle screw-rod system fixation, and after the cyclic loading in flexion-extension mode. The stability tended to decrease after the bilateral cage placement as compared with the intact for all loading cases except flexion. In flexion, the angular displacement decreased to 80% of the intact. However, there was no significant statistical difference seen in stability between intact and after bilateral spacer placement. Following the addition of posterior fixation using pedicle screw-rod system, the stability significantly increased in all directions. Cyclic loading did not have any significant effect on the stability. Stand-alone cages restore motion to near-intact levels at best, and supplement instrumentation is essential for significantly increasing the stability of the decompressed segment. The effects of cage geometry and Young's modulus of the cage material do not seem to influence the stability, as compared with the other cagedesigns, especially after supplemental fixation with a posterior system.


High-grade slippage of the lumbar spine in a rat model of spondylolisthesis: effects of cyclooxygenase-2 inhibitor on its deformity.

Radiographic and histologic evaluation of spondylolisthesis in a rat model. To investigate the effects of etodolac, a cox-2 inhibitor, on the severity of spondylolisthesis in a 4-week-old rat model. Spondylolisthesis occurs associated with spondylolysis in some pediatric patients. In such patients, the percent of forward slippage varies individually ranging between 0% and 100%. The factors determining the severity of forward slippage have not been clarified as yet. In earlier studies, we found that growth plate stress fracture was the basic lesion and that slippage was a consequence of the stress fracture. Hence, we hypothesized that the capacity of bone healing might be an important determinant of the degree of forward slippage. A lumbar spine slippage model was prepared in 4-week-old rats with vertebral physis fracture. To disrupt the fracture healing, the cyclooxygenase-2 (cox-2) inhibitor etodolac was used, and its effects on slippage and deformity were evaluated radiologically and histologically. In the etodolac group, forward slip significantly increased (P < 0.05) to the Meyerding Grade III while in the control rats it was Grade I or II. Bone remodeling of the vertebral body was suppressed by etodolac. Histologically, epiphyseal separation with slippage was observed in all the control and etodolac-treated rats. However, in the etodolac-treated group, the epiphyseal plate was greatly separated and did not present periosteal thickening at the physis fracture site. Vertebral forward slippage occurred in young rats after epiphyseal separation. In the etodolac group, slippage increased as deterioration of the bone healing capacity increased. Poor bony healing is suggested as one of the determinants of high-grade spondylolisthesis in children and adolescents.


Biomechanical comparison of lumbar spine with or without spina bifida occulta. A finite element analysis.

Biomechanical study using finite element model (FEM) of lumbar spine. Very high coincidence of spina bifida occulta (SBO) has been reported more than in 60% of lumbar spondylolysis. The altered biomechanics due to SBO is one considerable factor for this coincidence. Thus, in this study, the biomechanical changes in the lumbar spine due to the presence of SBO were evaluated. United States of America (USA). An experimentally validated three-dimensional nonlinear FEM of the intact ligamentous L3-S1 segment was used and modified to simulate two kinds of SBO at L5. One model had SBO with no change in the length of the spinous process and the other had a small dysplastic spinous process. Von Mises stresses at pars interarticularis were analyzed in the six degrees of lumbar motion with 400 N axial compression, which simulates the standing position. The range of motion at L4/5 and L5/S1 were also calculated. It was observed that the stresses in all the models were similar, and there was no change in the highest stress value when compared to the intact model. The range of motion was also similar in all the models. The lumbar kinematics of SBO was thus shown to be similar to the intact model. SBO does not alter lumbar biomechanics with respect to stress and range of motion. The high coincidence of spondylolysis in spines with SBO may not be due to the mechanical factors.


How the increase of the cervical disc space height affects the facet joint - an anatomy study.

In vitro study on the effect of increasing the height of the cervical disc space on the facet joint. To demonstrate how facet joint articulation is affected by increasing the cervical disc space height. A surgeon attempts to increase the disc space and inserts a larger artificial disc than normal in order to keep the intervertebral foramen open and the prosthesis stable. However, it is hypothesized by the current authors that this procedure could have an adverse effect on the facet joints. Computerized tomography images passing through the disc space and the center of the C4-C7 facet joints (sagittal plane) were obtained from 15 cadaveric cervical spine specimens. A 1-mm incremental increase to a total 5 mm in disc space height was performed to simulate the changes seen in disc replacement. The change in the facet joint articulation overlap and space in the sagittal plane at normal and each displacement was measured. Each 1-mm incremental increase in disc space at C4-C5 translated to a decrease in the facet joint articulation overlap in the sagittal plane by approximately 8%. The mean facet joint space increased approximately 0.8 mm. At the C5-C6 and the C6-C7 levels, the articulation overlap decreased by approximately 7% and the facet joint space increased approximately 0.8 mm. There is a significant decrease of the facet joint articulation overlap in the sagittal plane and an increase in the facet joint space following an increase in the cervical disc space. The inappropriate increase of the disc space height may result in facet joint subluxation and could lead to the accelerated failure of the artificial disc.


Three dimensional finite element analysis of the pediatric lumbar spine. Part II: biomechanical change as the initiating factor for pediatric isthmic spondylolisthesis at the growth plate.

A non-linear 3-dimensional finite element pediatric lumbar spine model with vertebral growth plate and apophyseal bony ring was developed. Lumbar spondylolysis was simulated in the model. The Von Mises stresses in the structures surrounding the vertebral growth plate, including apophyseal bony ring and osseous endplate were calculated in various loading modes. Instantaneous axis of rotation (IAR) path from flexion to extension was also analyzed. The results were compared with those of the intact model and the literature. The IAR path was at the posterior disc-endplate space of the lower vertebra in the intact spine, and moved cranially towards the upper-posterior disc space in the lytic spine. This was in agreement with in vivo radiological data by Sakamaki et al. [19]. During various loading modes, stresses in the spondylolytic pediatric model were higher than that of the intact model; ranging from 1.1 to 6.0 times, with the highest value in extension at the growth plate. In conclusion, FE models indicate that stress concentrations in the lytic model increase at the growth plate which may lead to physis stress fracture leading to spondylolisthesis.


Three-dimensional finite element analysis of the pediatric lumbar spine. Part I: pathomechanism of apophyseal bony ring fracture.

The purpose of this study was to (1) develop a three-dimensional, nonlinear pediatric lumbar spine finite element model (FEM), and (2) identify the mechanical reasons for the posterior apophyseal bony ring fracture in the pediatric patients. The pediatric spine FE model was created from an experimentally validated three-dimensional adult lumbar spine FEM. The size of the FEM was reduced to 96% taking into account of the ratio of the sitting height of an average 14-years-old children to that of an adult. The pediatric spine was created with anatomically specific features like the growth plate and the apophyseal bony ring. For the stress analyses, a 10-N m moment was applied in all the six directions of motion for the lumbar spine. A preload of 351 N was applied which corresponds to the mean body weight of the 14-years-old group. The stresses at the apophyseal bony ring, growth plate and endplate were calculated. The results indicate that the structures surrounding the growth plate including apophyseal bony ring and osseous endplate were highly stressed, as compared to other structures. Furthermore, posterior structures in extension were in compression whereas in flexion they were in tension, with magnitude of stresses higher in extension than in flexion. Over time, the higher compression stresses along with tension stresses in flexion may contribute to the apophyseal ring fracture (fatigue phenomena).


Adult onset tethered cord syndrome associated with intradural dermoid cyst. A case report.

A case report and a review of literature. To describe a rare case of adult onset tethered cord syndrome associated with intradural dermoid cyst. General Orthopedics, Japan. A 50-year-old woman was referred to us because of right leg pain and pollakiuria. Neurological examinations and radiological assessments including myelography, computerized tomography scan and Magnetic resonance image were carried out. We diagnosed it as the adult onset tethered cord syndrome associated with an intradural cystic lesion. The cystic lesion was totally removed following laminectomy from L5 through S4. Histologically, the tumor was diagnosed as a dermoid cyst. Intradural dermoid could produce adult onset tethered cord syndrome, but it was not reported in the English literatures to our knowledge.


Lumbar spinal disorders in patients with athetoid cerebral palsy. A clinical and biomechanical study.

Radiologic study for patients with athetoid cerebral palsy (CP), and a biomechanical study using the finite-element model (FEM). To understand the lumbar disorders of athetoid CP patients and the etiology based on the results from the FEM study. Cervical spondylotic myelopathy is a well-identified spinal disorder associated with cerebral palsy, especially in athetoid type. One can rationalize that the athetoid involuntary trunk movement may induce stress-related lumbar disorders. Until now, very few investigations have been conducted on lumbar disorders that could occur in patients with CP. Sixty-one cases with athetoid cerebral palsy were clinically reviewed. Radiographs of the lumbar spine in 30 cases with low back pain were taken. From these radiographs, the incidence of lumbar spondylolysis and endplate lesion was analyzed. The biomechanical study was conducted using a three-dimensional FEM of the ligamentous lumbar spine. Axial compression of 400 N was applied to simulate preload on the spine during the standing position followed with 10.6 Nm moment to simulate extension and axial rotation. The combined motion of extension and axial rotation was also simulated. During supine position, pure extension and rotation were simulated, and no preload was applied. The von Mises stresses were computed at the pars interarticularis at the each level and compared for different motions. Among the 61 patients, 41 complained of symptoms such as low back and leg pain. Thirty of these 41 patients gave their consents to undergo radiographic evaluation. Twenty-eight of the 30 patients (93.3%) showed stress-related disorders such as the spondylolysis and/or vertebral endplate lesions. Spondylolysis was found in 18 of the 30 patients (60.0%). Spondylolysis was observed at the multiple levels in 4 patients involving two levels in 2 cases and three levels in the other 2 cases. Vertebral endplate lesions (deformity) were seen in 26 (86.7%) of the 30 patients. Overall, the lesions (deformity) were found in 109 of 330 endplates (33.0%) out of all lumbar endplates in the 30 patients. The FEM based results showed that stresses at pars interarticularis of L5 were the highest of all levels in all loading modes, with or without preload. However, compared with the extension or axial rotation alone modes, the combined motion of extension and rotation showed higher stresses at the pars interarticularis. The athetoid involuntary movements in CP patients may cause stress-related lumbar disorders. Especially, combined extension and rotation due to the involuntary trunk motion may contribute to the high incidence of spondylolysis.


Extruded lumbar osseous endplate causing long-term radiculopathy in an adult: an endoscopic excision.

In this report, we described an adult case that had a long-term radiculopathy due to an extruded osseous endplate of the lumbar spine at the L5-S1 intervertebral disc level. The osseous material inside the extruded material was not absorbed, and it had continued compressing the nerve root for one year. Endoscopically, the bony fragment was successfully removed. After the surgery, the patient's symptom disappeared, and neurological deficits became normalized. In conclusion, we propose that surgical intervention should be taken into account for the treatment of HNP, when the extruded material contains bony fragment such as osseous endplate.


MRI signal changes of the pedicle as an indicator for early diagnosis of spondylolysis in children and adolescents. A clinical and biomechanical study.

Clinical review of pediatric patients with lumbar spondylolysis and biomechanical analysis using finite-element lumbar spine model. To evaluate the usefulness of the signal changes observed on MR images of the pedicle for the early diagnosis of spondylolysis, and to investigate the pathomechanism of the signal changes based on the stresses in pedicles, as predicted using finite-element analyses. Furthermore, to evaluate the usefulness of the signal change to predict the bony healing following conservative treatment. Since early-stage spondylolysis can achieve osseous healing conservatively, it is important to diagnose this disorder as early as possible. Presently, there is no well-established, noninvasive, and reliable diagnostic tool for the early diagnosis. Thirty-seven pediatric patients with spondylolysis were included. Sixty-eight defects were examined and their stages as revealed on CT scans were recorded. High signal changes (HSC) of the pedicles on axial T2-weighted MRI were compared with the CT-based stages of the defect. Among them, 16 patients, including 15 boys and 1 girl, were treated conservatively for at least a 3-month period. Bony healing of the fracture site was evaluated on CT, and the results were compared between two groups with or without HSC at the initial consultation. Using a three-dimensional nonlinear finite-element model of the L3-L5 segment, stress distributions in the pars and pedicle regions were analyzed in response to 400 N compression and 10.6 Nm moment. Based on CTs, 68 pars defects were classified as follows: 8 very early, 24 late-early, 16 progressive, and 20 terminal stages. All defects in very early and late-early stages (100%) showed HSC on T2-weighted MRI at the ipsilateral pedicle. Among 16 progressive stages, eight (50%) showed HSC, while no defects of the terminal stage (0%) were found to have HSC. In total, 29 pars defects were treated conservatively out of 16 patients. In 19 of the HSC positive defects, 15 (79%) showed bony healing after the conservative treatment, whereas none of the 10 HSC negative defects (0%) showed any healing. The results were statistically significant at P < 0.05 (chi). Stress results from the finite-element model indicated that pars interarticularis showed the highest value in all loading modes, and the pedicle showed the second highest. The correlation between the high stresses in the pedicle and the corresponding HSC suggest that signal changes in MRI could be used as an indicator for early diagnosis of spondylolysis. The HSC of the pedicle provided useful information to diagnose early stage spondylolysis. Furthermore, the HSC may be a good indicator as to whether a bony union will result from conservative treatment.


Decompression surgery for lumbar spondylolysis without fusion: A review article.


Preservation of C7 spinous process does not influence the long-term outcome after laminoplasty for cervical spondylotic myelopathy.

Axial pain is one of the major complications after laminoplasty, and preservation of C7 spinous process during the procedure can reduce the axial pain. However, it has not been elucidated whether laminoplasty preserving the C7 spinous process can maintain neurological improvement for a long time. The purpose of our retrospective study was to investigate the long-term neurological outcome after open-door laminoplasty preserving the C7 spinous process for cervical spondylotic myelopathy (CSM). Clinical and radiological outcomes were analysed in 42 patients who underwent open-door laminoplasty preserving C7 spinous process and followed up for more than 5 years. Neurological function was evaluated by means of the Japanese Orthopaedic Association (JOA) scoring system for cervical myelopathy. Axial pain was assessed using a visual analog scale (VAS) at the last examination. Alignment and motion of the cervical spine were measured from radiographs, and magnetic resonance imaging (MRI) was used to evaluate postoperative compression at C7. The mean JOA score was 9.4 before surgery and 12.0 at the latest follow-up. The mean VAS score in 26 patients score was 9.7/100. No compression of the spinal cord was observed in any MRI at the latest follow-up. Preservation of the C7 spinous process does not influence the long-term outcome of CSM after laminoplasty. Although we did not have a comparative group, the procedure described here should be considered as the solution.


Osteoactivin upregulates expression of MMP-3 and MMP-9 in fibroblasts infiltrated into denervated skeletal muscle in mice

In this study, we examined pathophysiological roles of osteoactivin, a functionally unknown type I membrane glycoprotein, in mouse skeletal muscle atrophied by denervation (sciatic neurectomy). Denervation increased the amounts of osteoactivin, vimentin, matrix metalloproteinase-3 (MMP-3), and MMP-9 in mouse gastrocnemius muscle. Interestingly, immunohistochemical analysis revealed that vimentin, MMP-3, and MMP-9 were mainly present in fibroblast-like cells infiltrated into denervated mouse gastrocnemius muscle, whereas osteoactivin was expressed in the sarcolemma of myofibers adjacent to the fibroblast-like cells. On the basis of these findings, we reasoned that osteoactivin in myocytes was involved in activation of the infiltrated fibroblasts. To address this issue, we examined effects of osteoactivin on expression of MMPs in fibroblasts in vitro and in vivo. Overexpression of osteoactivin in NIH-3T3 fibroblasts induced expression of MMP-3, but not in mouse C(2)C(12) myoblasts, indicating that osteoactivin might functionally target fibroblasts. Treatment with recombinant mouse osteoactivin increased the amounts of collagen type I, MMP-3, and MMP-9 in mouse NIH-3T3 fibroblasts. The upregulated expression of these fibroblast marker proteins was significantly inhibited by heparin, but not by an integrin inhibitor, indicating that a heparin-binding motif in the extracellular domain might be an active site of osteoactivin. In osteoactivin-transgenic mice, denervation further enhanced expression of MMP-3 and MMP-9 in fibroblasts infiltrated into gastrocnemius muscle, compared with wild-type mice. Our present results suggest that osteoactivin might function as an activator for fibroblasts infiltrated into denervated skeletal muscles and play an important role in regulating degeneration/regeneration of extracellular matrix.

American Journal of Physiology, Cell Physiology


Cyclooxygenase-2 inhibitor delays fracture healing in rats

Cyclooxigenase-2 (COX-2) inhibitors have been reported to delay fracture healing. To investigate the major inhibitory period of COX-2 inhibitors in fracture healing, we administrated etodolac, a COX-2-specific inhibitor, to a rat fracture model by altering the period of administration from early to late. After closed fractures had been created at the middle of the femoral shafts in 12-week-old Wister rats, a standardized dose of etodolac was administrated in three ways: group I received it for 3 weeks, group II for just the first week after operation, and group III for just the third (final) week. Group IV was the vehicle control group. Bone maturation was estimated by radiographic scoring system, and mechanically by a three-point bending test. In both the radiographic and mechanical studies, groups I and II showed lower scores than group IV, indicating that even a short period of administration of a COX-2-specific inhibitor in the early phase of fracture healing creates a risk of delayed healing. blacksquare, square, filled.


Athletes With Unilateral Spondylolysis Are at Risk of Stress Fracture at the Contralateral Pedicle and Pars Interarticularis --- A Clinical and Biomechanical Study

Unilateral spondylolysis is common in youths; its clinical and biomechanical features, especially effects on the contralateral side, are not fully understood. Unilateral spondylolysis predisposes the contralateral side to stress fracture, especially in athletes actively engaged in sporting activities involving torsion of the trunk. Case series and descriptive laboratory study. Thirteen athletes younger than age 20 with unilateral spondylolysis were included. The contralateral pedicle and pars of spondylolytic vertebrae were examined using computed tomography and magnetic resonance imaging. Using a finite element model of the intact ligamentous L3-S1 segment, stress distributions were analyzed in response to 400-N axial compression and 10.6-N.m moment in flexion, extension, lateral bending, and axial rotation. Unilateral spondylolysis was created in the model at L5. The stress results from the unilateral defect model were compared to the intact model predictions and correlated to the contralateral defects seen in patients. Among 13 patients, there were 6 early-, 2 progressive-, and 5 terminal-stage defects. Three (23.1%) showed contralateral stress fracture. Among them, 2 belonged to the progressive-stage and 1 to the terminal-stage spondylolysis group. The remaining 4 patients in the terminal defect group showed stress reactions, such as sclerosis at the contralateral pedicle. In the finite element analysis model with an L5 left spondylolysis, the stresses at the contralateral and pars interarticularis were found to increase in all loading modes, with increases as high as 12.6-fold compared to the intact spine. Unilateral spondylolysis could lead to stress fracture or sclerosis at the contralateral side due to an increase in stresses in the region. Surgeons should be aware of possibility of contralateral stress fractures in cases in which patients, especially athletes engaged in active sports, show unilateral spondylolysis and persistent low back pain complaints.


Effects of Charite artificial disc on the implanted and adjacent spinal segments mechanics using a hybrid testing protocol.

Finite element model of L3-S1 segment and confirmatory cadaveric testing were used to investigate the biomechanical effects of a mobile core type artificial disc (Charité artificial disc; DePuy Spine, Raynham, MA) on the lumbar spine. To determine the effects of the Charité artificial disc across the implanted and adjacent segments. Biomechanical studies of artificial discs that quantify parameters, like the load sharing and stresses, are sparse in the literature, especially for mobile-type core artificial disc designs. In addition, there is no standard protocol for studying the adjacent segmental effects of such implants. Human osteo-ligamentous spines (L1-S1) were tested before and after L5-S1 Charité artificial disc placement. The data were used to validate further an intact 3-dimensional (3-D) nonlinear L3-S1 finite element model. The model was subjected to 400-N axial compression and 10.6 Nm of flexion/extension pure moments (load control) or pure moments that produced the overall rotation of the L3-S1 Charité model equal to the intact case (hybrid approach). Resultant motion, load, and stress parameters were analyzed at the experimental and adjacent levels. Finite element model validation was achieved only with the load-controlled experiments. The hybrid approach, believed to be more clinically relevant, revealed that Charité artificial disc leads to motion increases in flexion (19%) and extension (44%) at the L5-S1 level. At the instrumented level, the decrease in the facet loads was less than at the adjacent levels; the corresponding decrease being 26% at L3-L4, 25% at L4-L5, and 13.4% at L5-S1 when compared to the intact. Intradiscal pressure changes in the L4-L5 and L3-L4 segments were minimal. Shear stresses at the Charité artificial disc-L5 endplate interface were higher than those at S1 interface. However, in the load control mode, the increase in facet loads in extension was approximately 14%, as compared to the intact case. The hybrid testing protocol is advocated because it better reproduces clinical observations in terms of motion following surgery, using pure moments. Using this approach, we found that the Charité artificial disc placement slightly increases motion at the implanted level, with a resultant increase in facet loading when compared to the adjacent segments, while the motions and loads decrease at the adjacent levels. However, in the load control mode that we believe is not that clinically relevant, there was a large increase in motion and a corresponding increase in facet loads, as compared to the intact.


Ipsilateral pedicle screw fixation and contralateral translaminar facet screw placement in conjunction with TLIF: Technical Note.


Pathomechanism of ligamentum flavum hypertrophy: a multidisciplinary investigation based on clinical, biomechanical, histologic, and biologic assessments.

A multidisciplinary study involving clinical, histologic, biomechanical, biologic, and immunohistologic approaches. OBJECTIVE.: To clarify the pathomechanism of hypertrophy of the ligamentum flavum. The most common spinal disorder in elderly patients is lumbar spinal canal stenosis, causing low back and leg pain, and paresis. Canal narrowing, in part, results from hypertrophy of the ligamentum flavum. Although histologic and biologic literature on this topic is available, the pathomechanism of ligamentum flavum hypertrophy is still unknown. The thickness of 308 ligamenta flava at L2/3, L3/4, L4/5, and L5/S1 levels of 77 patients was measured using magnetic resonance imaging. The relationships between thickness, age, and level were evaluated. Histologic evaluation was performed on 20 ligamentum flavum samples, which were collected during surgery. Trichrome and Verhoeff-van Gieson elastic stains were performed for each ligamentum flavum to understand the degree of fibrosis and elastic fiber status, respectively. To understand the mechanical stresses in various layers of ligamentum flavum, a 3-dimensional finite element model was used. Von Mises stresses were computed, and values between dural and dorsal layers were compared. There were 10 ligamenta flava collected for biologic assessment. Using real-time reverse transcriptase polymerase chain reaction, transforming growth factor (TGF)-beta messenger ribonucleic acid expression was quantitatively measured. The cellular location of TGF-beta was also confirmed from 18 ligamenta flava using immunohistologic techniques. The ligamentum flavum thickness increased with age, however, the increment at L4/5 and L3/4 levels was larger than at L2/3 and L5/S1 levels. Histology showed that as the ligamentum flavum thickness increased, fibrosis increased and elastic fibers decreased. This tendency was more predominant along the dorsal side. Von Misses stresses revealed that the dorsal fibers of ligamentum flavum were subjected to higher stress than the dural fibers. This was most remarkably observed at L4/5. The largest increase in ratio observed between the dorsal and dural layer was approximately 5-fold in flexion at L4/5 in flexion. Expression of TGF-beta was observed in all ligamenta flava, however, the expression decreased as the ligamentum flavum thickness increased. Immunohistochemistry showed that TGF-beta was released by the endothelial cells, not by fibroblasts. Fibrosis is the main cause of ligamentum flavum hypertrophy, and fibrosis is caused by the accumulation of mechanical stress with the aging process, especially along the dorsal aspect of the ligamentum flavum. TGF-beta released by the endothelial cells may stimulate fibrosis, especially during the early phase of hypertrophy.


Signal intensity of cerebrospinal fluid on MR images can indicate the severity of lumbar spinal canal stenosis.


Spondylolysis fracture angle in children and adolescents on CT indicates the facture producing force vector A biomechanical rationale.


Biomechanical Rationale of Endoscopic Decompression for Lumbar Spondylolysis As An Effective Minimally Invasive Procedure - A study based on the Finite Element Analysis.

We evaluated the biomechanical behavior of the endoscopic decompression for lumbar spondylolysis using the finite element technique. An experimentally validated, 3-dimensional, non-linear finite element model of the intact L3 - 5 segment was modified to create the L4 bilateral spondylolysis and left-sided endoscopic decompression. The model of Gill's laminectomy (conventional decompression surgery of the spondylolysis) was also created. The stress distributions in the disc and endplate regions were analyzed in response to 400 N compression and 10.6 Nm moment in clinically relevant modes. The results were compared among three models. During the flexion motion, the pressure in the L4/5 nucleus pulposus was 0.09, 0.09 and 0.16 (MPa) for spondylolysis, endoscopic decompression and Gill's procedure, respectively. The corresponding stresses in the annulus fibrosus were 0.65, 0.65 and 1.25 (MPa), respectively. The stress at the adjoining endplates showed an about 2-fold increase in the Gill's procedure compared to the other two models. The stress values for the endoscopic and spondylolysis models were of similar magnitudes. In the other motions, i. e., extension, lateral bending, or axial rotation, the results were similar among all of the models. These results indicate that the Gill's procedure may lead to an increase in intradiscal pressure (IDP) and other biomechanical parameters after the surgery during flexion, whereas the endoscopic decompression did not change the segment mechanics after the surgery, as compared to the spondylolysis alone case. In conclusion, endoscopic decompression of the spondylolysis, as a minimally invasive surgery, does not alert mechanical stability by itself.


Continuous muscle stretch prevents disuse muscle atrophy and deterioration of its oxidative capacity in rat tail-suspension models

The purpose of this study was to evaluate the effect of continuous muscle stretch on disuse-atrophied muscles. Sprague-Dawley rats were used and divided into five groups: control group, hind limb suspended for 3 and 7 days, and hind-limb suspension plus strenuous continuous muscle stretch for 3 and 7 days. In the hind-limb suspension plus strenuous continuous muscle stretch groups, the gastrocnemius-plantaris-soleus muscles were stretched using a plastic plate that immobilized the ankle joint at the maximum dorsal flexed position during the hind-limb suspension period. The intracellular energy metabolism of the working muscle during electric stimulation was evaluated by phosphorus-31 magnetic resonance spectroscopy in vivo. Changes in phosphocreatine, inorganic phosphate, and the intracellular pH were monitored to evaluate intramuscular oxidative capacity. Maximum tension and muscle wet mass were also measured. The oxidative capacity, muscle wet weight, and maximum tension decreased after hind-limb suspension. The muscle oxidative capacity at control levels was maintained during the first 3 days in muscles subjected to continuous strenuous stretch. It was also effective to prevent the decrease in muscle mass and maximum twitch tension during the initial 3 days. However, the effects did not persist. Continuous strenuous stretch was effective to prevent disuse muscle atrophy and its functional deterioration; however, its effects did not last long.

American Journal of Physical Medicine & Rehabilitation


Vertebral forward slippage in immature lumbar spine occurs following epiphyseal separation and its occurence is unrelated to disc degeneration. Is the pediatric spondylolisthesis a physis stress fracture of vertebral body?

Radiographic and histologic evaluation of a rat model of lumbar spine slippage. To clarify the pathomechanism of slippage in the immature spine. There are controversial hypotheses regarding the pathogenesis of slippage of the pediatric spine with pars defects. Some studies supported that disc degeneration was its cause, while others indicated the growth plate injury was the cause. An immature lumbar spine slippage model in 4-week-old rats was used. Following posterior destabilizing surgery, the lumbar spine was radiographically and histologically examined at 1, 3, 5, and 7 days after surgery. Radiographically, slippage occurred about 7% in the % slip on day 7, and no slippage was observed before day 5. Histologically, epiphyseal separation also appeared on day 7; before day 5, the growth plate showed no abnormalities. Within 7 days after the operation, the anulus fibrosus did not show any sign indicating degeneration. The nucleus pulposus was also normal up to day 7. The findings of this study support the hypothesis that vertebral forward slippage of the immature spine occurs following epiphyseal separation and its occurrence is unrelated to disc degeneration.


Union of defects in the pars interarticularis of the lumbar spine in children and adolescents. Radiological outcome after conservative treatment.

Lumbar spondylolysis can heal with conservative treatment, but few attempts have been made to identify factors which may affect union of the defects in the pars. We have evaluated, retrospectively, the effects of prognostic variables on bony union of pars defects in 134 young patients less than 18 years of age with 239 defects of the pars who had been treated conservatively. All patients were evaluated by CT scans when first seen and more than six months later at follow-up. The results showed that the spinal level and the stage of the defects were the predominant factors. The site of the defects in the pars, the presence or development of spondylolisthesis, the condition of the contralateral pars, the degree of lumbar lordosis and the degree of lumbar inclination all significantly affected union.

The Journal of Bone and Joint Surgery. British Volume


Muscular oxidative capacity in ovariectomized rats discussion on the endurance performance of female athletes with sports-related-amenorrhea


Three successive stress fractures at the same vertebral level in an adolescent baseball player


The Pathogenesis of Slippage and Deformity in the Pediatric Lumbar Spine --- A Radiographic and Histologic Study using a New Rat In Vivo Model


A new endoscopic technique to decompress lumbar nerve roots affected by spondylolysis. Technical note

The authors describe a new endoscopic technique to decompress lumbar nerve roots affected by spondylolysis. Short-term clinical outcome was evaluated. Surgery-related indications were: 1) radiculopathy without low-back pain; 2) no spinal instability demonstrated on dynamic radiographs; and 3) age older than 40 years. Seven patients, four men and three women, fulfilled these criteria and underwent endoscopic decompressive surgery. Their mean age was 60.9 years (range 42-70 years). No subluxation was present in four patients, whereas Meyerding Grade I slippage was demonstrated in three. For endoscopic decompression, a skin incision of 16 to 18 mm in length was made, and fenestration was performed to identify the affected nerve root. The proximal stump of the ragged edge of the spondylotic lesion, and the fibrocartilaginous mass compressing the nerve root were removed. The follow-up period ranged from 6 to 22 months (mean 11.7 months). Clinical outcome was evaluated using Gill criteria; in three patients the outcome was excellent, and in four it was good. This new endoscopic technique was useful in the decompression of nerve roots affected by spondylolysis, the technique was minimally invasive, and the clinical results were acceptable.


Electrical Stimulation Prevents Deterioration of the Oxidative Capacity of Disuse-Atrophied Muscles in Rats

The purpose of this study was to evaluate the effects of electrical stimulation on disuse-atrophied muscles. Sprague-Dawley rats were used and divided into three groups: control (C), hind-limb suspended for 7 d (HS), and HS plus transcutaneous electrical stimulation for 7 d (ES). In the ES group, transcutaneous electrical stimulation was induced at 1 Hz for 1 h every day to condition the gastrocnemius-plantaris-soleus muscles. Muscle oxidative capacity was evaluated by 31P-MRS in vivo. Maximum tension and muscle wet mass were also measured. Muscle oxidative capacity decreased within 1 wk in HS; however, it was maintained when electric stimulation was applied to the suspended limb. The maximum twitch tension in HS was significantly smaller than that in C (p < 0.05), while in ES it did not differ from that in C. The muscle mass was significantly smaller in the HS and ES groups compared to C (p < 0.05). These data indicated that twitch electrical stimulation was effective in preventing deterioration of muscle functions, such as maximum tension and oxidative capacity, induced by 1 wk of disuse.

Aviation, Space, and Environmental Medicine


Cyclooxygenase-2 Inhibitor Inhibits the Fracture Healing

骨折後の治療期間に及ぼす麻酔薬の影響を調べるため，麻酔を投与したラットと投与しなかったラットの大腿骨を用い，骨折後の時間経過に伴う骨の強度，剛性の測定を行った．その結果，麻酔薬を用いることで骨の強度および剛性の回復が遅れることを示した．

Journal of Physiological Anthropology and Applied Human Science


Comparison of spine movements between normal pediatric spine and spondylolytic spine with reference to instantaneous axis of rotation

A radiologic study of lumbar kinematics in the pediatric spine was conducted. To clarify the kinematic alteration in the pediatric spine with pars defects by measuring the location of the instantaneous axis of rotation. Vertebral slippage and deformities such as wedging of L5 are observed frequently in pediatric patients with spondylolysis. However, the kinematics of pediatric lumbar spine with pars defects has not yet been well documented. Radiographs of 70 pediatric patients (57 boys and 13 girls) with low back pain were examined. The control group (without spondylolysis) consisted of 22 patients (15 boys and 7 girls; mean age, 14.6 years; range, 10-18 years), and the lysis group (with spondylolysis at L5) consisted of 48 patients (42 boys and 6 girls; mean age, 14.5 years; range, 11-18 years). The lysis group was further divided into four subgroups according to the stage of defects and existence of slippage: Group 1 (early stage defect), Group 2 (progressive stage defect), Group 3 (terminal stage defect without slippage), and Group 4 (terminal stage defect with slippage of more than 5%; olisthesis). The instantaneous axis of rotation at L4-L5 and L5-S1 from the extended to the flexed position was measured on lateral dynamic radiograms taken in with the subject in the recumbent position. The relation between lumbar index and the site of instantaneous axis of rotation at L5-S1 also was analyzed. The site of instantaneous axis of rotation at L5-S1 and L4-L5 in the control group was not located in the rotating cranial vertebra. In 1 of the 11 patients in the early-stage subgroup, the instantaneous axis of rotation at L5-S1 was found in the cranial vertebra. In 4 of the 11 patients in the progressive stage, 11 of the 16 patients in the terminal stage, and in 7 of the 10 patients in the olisthesis subgroup, the instantaneous axis of rotation was located in the cranial vertebra. Cranial deviation in the instantaneous axis of rotation was observed more frequently in the vertebra with severe deformity less than 80% of the lumbar index than in the vertebra with milder deformity. The instantaneous axis of rotation deviated cranially as the stage of pars defects advanced, and as the wedge deformity increased. Kinematic alteration of the lumbar spine in pediatric patients with spondylolysis may affect chondrocytes of the endplate, perhaps contributing to the consequent spine deformities occurring secondarily to spondylolysis.


Characteristics of velocity-controlled knee movement in patients with cervical compression myelopathy: what is the optimal rehabilitation exercise for spastic gait?

The isokinetic strength of knee extensors and flexors was measured at various controlled velocities in patients with spastic paraparesis caused by cervical compression myelopathy. To evaluate leg function objectively in patients with myelopathy. Cervical compression myelopathy causes varying degrees of spastic paresis in the legs and affects the activities of patients. However, the leg function characteristics of the patients have not been fully elucidated. Velocity-controlled voluntary knee movements were studied in 39 patients (25 men and 14 women) with compression myelopathy. Their mean age was 60.2 years (range, 44-77 years). The patients were divided into Group A (ambulation without aid, n = 22) and Group AA (ambulation with aid, n = 17). Isometric peak torque values were measured in knee flexor and extensor muscles at 60 degrees of knee flexion, and isokinetic peak torque values were determined in maximal voluntary concentric movements of these muscles at constant angle velocities of 40 degrees, 80 degrees, 120 degrees, 160 degrees, and 180 degrees per second. The relative strength (percentage of isometric peak torque value) of the isokinetic motion was calculated at each velocity. In both groups, the relative strength decreased as the velocity increased, and the degree of reduced strength in the flexors at the high velocities of 160 degrees and 180 degrees per second was significantly greater in Group AA than in Group A (P < 0.05), whereas no significant difference was found in the extensors between the groups. The results indicate that isokinetic strength at a high velocity may reflect the severity of spastic paresis in the legs resulting from compression myelopathy.


Evaluation of leg motor function affected by cervical compression myelopathy


Slippage mechanism of pediatric spondylolysis:biomechanical study using immature calf spines --- Discussion based on a biomechanical study using immature calf spines

This study analyzed the skeletal-age-dependent strength of the lumbar growth plate to resist anterior shearing forces using the MTS system in the immature calf spine with pars defects. To clarify the pathomechanism of the skeletal-age-dependent incidence of slippage in pediatric patients with pars defects by comparing the strength of the lumbar growth plate among three skeletal age groups. Isthmic spondylolisthesis occurs and progresses more frequently during the growth period, whereas it is rare afterward. However, little evidence has been demonstrated to elucidate the etiology. For this study, 15 lumbar functional spine units were divided into three groups according to their skeletal ages. Five were from neonates (Group 1), five from calves approximately 2 months old (Group 2), and five from calves about 24 months old (Group 3). An anterior shearing force was applied to each specimen until failure, after bilateral pars defects were created. Failure load (newtons) and displacement at failure (millimeters) were calculated from the load-displacement curve. The site of failure was confirmed by plain radiograph. All 15 functional spine units failed at the growth plate. The failure load was 242.79 +/- 46.05 N in Group 1, 986.40 +/- 124.16 N in Group 2, and 2024.54 +/- 245.53 N in Group 3. Statistically significant differences were found among the three groups (P < 0.05). The displacement at failure was 7.52 +/- 1.84 mm in Group 1, 11.10 +/- 2.30 mm in Group 2, and 8.15 +/- 2.66 mm in Group 3. There were no significant differences among the groups. The results indicate that the strength of the growth plate, the weakest link in this model, against anterior shearing forces depends on the skeletal maturity, and that the biomechanical weakness of the growth plate plays an important role in the slippage mechanism.

脊椎分離症のメカニズムを明らかにするために若年牛の背骨を使ったすべり曲げ試験を行い若年期固有の骨構造が脊椎分離に与える影響を定量的に検討し，骨構造が大きな影響を与えることを解明した．


Evaluation of Disuse Atrophy of Rat Skeletal Muscle Based on Muscle Energy Metabolism Assessed by 31P-MRS

The purpose of this study was to evaluate disuse atrophy of skeletal muscle using a hind-limb suspension model, with special reference to energy metabolism. Twenty-four Sprague-Dawley rats were divided into four groups: control group (C), hind-limb suspended for 3 days (HS-3), for 7 days (HS-7) and for 14 days (HS-14). The gastrocnemius-plantaris-soleus (GPS) muscles in each group were subjected to the following measurements. After a 2-min rest, contraction of the GPS muscles was induced by electrical stimulation of the sciatic nerve at 0.25 Hz for 10 min, then the frequency was increased to 0.5 and 1.0 Hz every 10 min. During the stimulation, twitch forces were recorded by a strain gauge, and 31P-MRS was performed simultaneously. Maximum tension was measured at the muscle contraction induced at 0.25 Hz; the wet weight of the whole and each muscle in the GPS muscles was also measured. From the 31P-MR spectra during muscle contraction, the oxidative capacity was calculated and compared among the groups. The weights of the whole GPS muscles in C, HS-3, HS-7 and HS-14, were 2.66 +/- 0.09, 2.39 +/- 0.21, 2.34 +/- 0.21 and 2.18 +/- 0.14 (g) respectively. Thus, the muscle mass significantly decreased with time (p < 0.05). Among the GPS muscles, the decrease in weight of the soleus muscle was especially remarkable; in the HS-14 group its weight decreased to 60% of that in the C group. We evaluated maximum tension and oxidative capacity as the muscle function. The maximum tensions in C, HS-3, HS-7 and HS-14 were 519 +/- 43, 446 +/- 66, 450 +/- 23 and 465 +/- 29 (g), respectively. This was significantly greater in the C group than in any other groups, however there were no significant differences among the three HS groups. The oxidative capacity during muscle contraction in the C group was higher than in any HS group and it did not further decrease even if the suspension of the limbs was prolonged beyond 3 days. The present study showed that in disuse atrophy, muscle mass and muscle function did not change simultaneously. Thus, it is necessary to develop countermeasures to prevent muscle atrophy and muscle function deterioration independently.


Development of spondylolytic olisthesis in adolescents

Although it has been well documented that slippage in patients with spondylolysis is most prevalent during the growth period, the exact time when slippage initiates and halts during the growth period is still unknown. Moreover, the contribution of spinal deformities, such as wedging of the vertebral body to the slippage, remains controversial. To clarify when slippage in pediatric spondylolysis initiates and halts. Retrospective study. We radiographically examined 46 athletes under 18 years of age with spondylolysis at the fifth lumbar vertebra (L5). The mean age at the first consultation was 13.3 years. The average follow-up period was 6.0 years. Longitudinal observation of slippage at L5 on radiogram in correlation with the maturity of the lumbar spine. From a lateral radiogram of each patient, percent slippage, lumbar index (LI), and skeletal age of the affected vertebra were measured. Changes in the percent slippage over time were investigated, and the correlation between the percent slippage and LI was analyzed. From the cartilaginous stage to the apophyseal stage, the slippage increased in 80.0% of the patients (16 of 20). From the cartilaginous stage to the epiphyseal stage, slippage increased in 11.1% of the patients (3 of 27). None of the patients (0 of 22) showed an increase after the epiphyseal stage. In 20 patients in whom slippage increased during the follow-up period, the percent slippage at the final consultation and the LI at the first consultation showed no significant correlation; however, the percent slippage and the LI at the final consultation were significantly (p<.01) correlated. In conclusion, slippage was more prevalent in individuals of a younger skeletal age whose lumbar spine was immature, and it halted during the epiphyseal stage when the growth period was over and the vertebra matured. Furthermore, the results suggest that wedge deformity of an affected vertebra might be the result rather than the cause of slippage.


Effects of specific warm-up at various intensities on energy metabolism during subsequent exercise

To investigate the effects of specific warm-up at various intensities on energy metabolism during subsequent intense exercise. specific warm-up was consisted of 3 sets of wrist flexions for 5 min, with each set followed by a 3-min rest. The intensity of specific warm-up was set at 20%, 30% or 40% of maximal voluntary contraction (MVC). The subjects then performed a set of wrist flexions at 60% MVC for 4 min as the criterion exercise. For the control experiment, criterion exercise was done without specific warm-up. Five healthy volunteers. using phosphorus-31 magnetic resonance spectroscopy, spectra were obtained from the wrist flexor muscles to determine the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) and intracellular pH. The Pi/PCr during the criterion exercise after specific warm-up at any intensity was not significantly different from that without specific warm-up. The intracellular pH during the criterion exercise after specific warm-up at 30% or 40% MVC was significantly higher than that without specific warm-up. These results indicate that mild warm-up exercise could inhibit the development of intracellular acidosis during subsequent intense exercise.

The Journal of Sports Medicine and Physical Fitness


特集 アスリートの痛みを可視化する-画像で診る,鏡で視る-【特集編集:西良浩一】


特集 脊椎内視鏡下手術の進化・深化〈展望:痛みを視る〉 Modic Changeの痛みを視る Modic Changeによる慢性腰痛に対する全内視鏡下手術の臨床成績と術中鏡視所見


特集 脊椎内視鏡下手術の進化・深化〈各論(2)FESS〉 経椎間孔的全内視鏡下椎間板切除術(TF-FED)


特集 脊椎内視鏡下手術の進化・深化〈総論〉 FEDからFESSへの変遷

特集 脊椎内視鏡下手術の進化・深化〈総論〉 FEDからFESSへの変遷


特集 脊椎内視鏡下手術の進化・深化 緒言

特集 脊椎内視鏡下手術の進化・深化 緒言


子どもの腰痛疾患診療におけるMRIのみでの骨評価

子どもの腰痛疾患診療におけるMRIのみでの骨評価


特集:大人とこどものスポーツ外来 上肢・体幹編 【こども編】腰椎骨端輪骨折

特集:大人とこどものスポーツ外来 上肢・体幹編 【こども編】腰椎骨端輪骨折


特集:大人とこどものスポーツ外来 上肢・体幹編 【こども編】腰椎分離症(発育期)


復帰前に行う運動療法(ピラティス)

復帰前に行う運動療法(ピラティス)


分離すべりの基本理論とすべらせない方策

分離すべりの基本理論とすべらせない方策


特集 腰椎分離症のパラダイムシフト-理論を知り，理論を超える-【特集編集:西良浩一】巻頭言


One-Stage Reconstruction for Re-rupture of Achilles Tendon with Soft Tissue Infection: Using an Anterolateral Thigh Flap Incorporating a Vascularized Muscle Flap and a Strip of Iliotibial Tract.

Reconstruction is challenging in a patient with loss of a segment of Achilles tendon and infection in the overlying soft tissue. Here the authors describe one-stage tendon reconstruction, using an anterolateral thigh free flap incorporating a vascularized muscle flap and a strip of iliotibial tract in a patient with re-rupture of an Achilles tendon and soft tissue infection. Postoperative immobilization of the affected ankle using an external fixator enabled us to observe the flap directly and reduce pressure on the flap. The patient had a successful outcome, with no difficulty in walking, running, or climbing stairs and no limitation of range of motion at the ankle joint postoperatively. This is a promising technique for reconstruction of the Achilles tendon and treatment of infection as a one-step procedure.


Shoulder and elbow pain in elementary school baseball players: The results from a nation-wide survey in Japan

Despite recommendations on how to prevent baseball injuries in youths by the Japanese Society of Clinical Sports Medicine, shoulder and elbow pain still frequently occurs in young baseball players. We conducted a questionnaire survey among baseball players at elementary schools across the country to understand the practice conditions of players, examining the risk factors of shoulder and elbow pain in baseball players. The questionnaire survey was conducted among elementary school baseball players as members of the Baseball Federation of Japan in September 2015. A total of 8354 players belonging to 412 teams (average age: 8.9) responded to the survey. Among 7894 players who did not have any shoulder and/or elbow pain in September 2014, elbow pain was experienced in 12.3% of them, shoulder pain in 8.0% and shoulder and/or elbow pain in 17.4% during the previous one year. A total of 2835 (39.9% of the total) practiced four days or more per week and 97.6% practiced 3 h or more per day on Saturdays and Sundays. The risk factors associated shoulder and elbow pain included a male sex, older age, pitchers and catchers, and players throwing more than 50 balls per day. It has been revealed that Japanese elementary school baseball players train too much. Coaches should pay attention to older players, male players, pitchers and catchers in order to prevent shoulder and elbow pain. Furthermore, elementary school baseball players should not be allowed to throw more than 50 balls per day. Retrospective cohort study.