Taiki Furumoto, Daisuke Hamada, Keizo Wada, Ken Tomonari, Yasuaki Tamaki, Shota Shigekiyo, Tetsuya Matsuura and Koichi Sairyo : Cutoff values of knee extensor strength for stair ascent and descent after bicruciate-stabilized total knee arthroplasty., Journal of Orthopaedics, 75, 279-284, 2026.
(要約)
Patient satisfaction after total knee arthroplasty (TKA) is strongly influenced by the ability to ascend and descend stairs. Although knee extensor strength is considered essential for stair negotiation, the specific functional threshold values required for stair ascent and descent after bicruciate-stabilized (BCS) TKA remain unclear. This study aimed to identify functional factors associated with stair ascent and descent after BCS TKA and to determine cutoff values for knee extensor strength.This prospective cohort study included 94 patients (117 knees) who underwent unilateral BCS TKA between October 2017 and January 2023. Stair ascent and descent abilities were evaluated at 1 year postoperatively using a three-step staircase. Patients were classified into a normal ability group or a reduced ability group based on their stair negotiation pattern. Knee extensor strength, knee range of motion, and demographic variables were assessed. Multiple logistic regression analyses were performed separately for stair ascent and stair descent. Cutoff values were determined using receiver-operating characteristic (ROC) curve analysis.For stair ascent, knee extensor strength, age, and sex were independently associated with stair ascent ability. The cutoff value of knee extensor strength required for normal stair ascent was 1.04 Nm/kg (area under the curve [AUC] = 0.76). For stair descent, knee extensor strength was the only independent factor associated with performance. The cutoff value required for normal stair descent was 1.10 Nm/kg (AUC = 0.86).Successful stair ascent and descent after BCS TKA require sufficient knee extensor strength. The identified cutoff values may serve as clinically useful reference targets for postoperative rehabilitation aimed at improving stair negotiation ability.
Keizo Wada, Daisuke Hamada, Yasuaki Tamaki, Shota Shigekiyo and Koichi Sairyo : Relationship between intraoperative knee kinematics assessed by navigation system and patient-reported outcomes of bicruciate-stabilized total knee arthroplasty., The Knee, 57, 438-443, 2025.
(要約)
This study aimed to determine the relationship between intraoperative kinematics using a navigation system and clinical outcomes of bicruciate-stabilized total knee arthroplasty (BCS-TKA). The study tested the hypothesis that reproducing native knee kinematics would result in favorable clinical outcomes.The cohort included 67 knees in 57 patients who underwent BCS-TKA using a navigation system, which automatically recorded tibial rotation angle to the femur from 0° to 120° of passive knee flexion. Patient-reported outcomes were assessed preoperatively and 1 year postoperatively using the 2011 Knee Society Score (KSS). Correlations among KSS subjective domains were assessed using Spearman's correlation coefficient. Based on the 1-year postoperative Symptom score, the patients were divided into a lowest-quartile group and an other-quartiles group. The Mann-Whitney U test was used to evaluate differences between the groups.Tibial rotational kinematics after BCS-TKA showed internal rotation in early knee flexion and gradual internal rotation during deep knee flexion with slight external rotation in mid-flexion. Significant differences were found between pre- and 1-year postoperative subjective domain scores. At 1 year postoperatively, Symptom score correlated with Satisfaction (r = 0.5, P < 0.001) and Functional activities (r = 0.4, P < 0.001). Tibial rotational kinematics showed significantly less tibial internal rotation during early knee flexion (0-30°) in the lowest quartile group.Intraoperative tibial internal rotation during early knee flexion may influence postoperative symptom severity after BCS-TKA. Future research should assess the impact of intraoperative adjustments on tibial rotation and postoperative symptoms.
Yasuyuki Ohmichi, Daisuke Hamada, Keizo Wada, Yasuaki Tamaki, Shota Shigekiyo and Koichi Sairyo : Robotic-assisted total knee arthroplasty improved component alignment in the coronal plane compared with navigation-assisted total knee arthroplasty: a comparative study., Journal of Robotic Surgery, 17, 6, 2831-2839, 2023.
(要約)
The purpose of this study was to directly compare implant placement accuracy and postoperative limb alignment between robotic-assisted total knee arthroplasty and navigation-assisted total knee arthroplasty. This retrospective case-control study included a consecutive series of 182 knees (robotic-assisted group, n = 103 knees; navigation-assisted group, n = 79). An image-free handheld robotic system (NAVIO) or an image-free navigation system (Precision N) was used. Component and limb alignment were evaluated on three-dimensional computed tomography scans and full-length standing anterior-posterior radiographs. We compared the errors between the final intraoperative plan and the postoperative coronal and sagittal alignment of the components and the hip-knee-ankle angle between the two groups. The orientation of the femoral and tibial components in the coronal plane were more accurate in the robotic-assisted group than in the navigation-assisted group (p < 0.05). There was no significant difference in the orientation of the femoral and tibial component in the sagittal plane between the two groups. There were fewer outliers in the tibial coronal plane in the robotic-assisted group (p < 0.05). There was also no significant difference in the frequency of outlying values for coronal or sagittal alignment of the femoral component or sagittal alignment of the tibial component or the hip-knee-ankle angle between the two groups. Robotic-assisted total knee arthroplasty using a handheld image-free system improved component alignment in the coronal plane compared with total knee arthroplasty using an image-free navigation system. Robotic surgery helps surgeons to achieve personalised alignment that may result in better clinical outcomes.