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Background Precise biomechanical knowledge of individual components of the MCL is critical for proper MCL release during TKA. This study was to define the influences of the deep MCL and the POL on valgus and rotatory stability in TKA using cadaveric knees. Methods This study used six fresh-frozen cadaveric knees. All TKA procedures were performed using a cruciate-retaining TKA with a CT-free navigation system. We did a sequential sectioning on each knee, S1; femoral arthroplasty only, S2; medial half tibial resection with spacer, S3; anterior cruciate ligament cut, S4; tibial arthroplasty, S5; release of the dMCL, S6; release of the POL. The navigation system monitored motion after application of 10 N-m valgus loads and 5 N-m internal and external rotation torques to the tibia at 0°, 20°, 30°, 60°, and 90° of knee flexion for each sequence. Results There were no significant differences in medial gaps. Internal rotation angles significantly increased after S2 at 0°, 20°, and 30°, and after S6 at 90°compared with those after S1. External rotation angles significantly increased after S3 at 0°, S4 at 60°, S5 at 0°, 30°and 90°, and after S6 at 30°, 60° compared with those after S1. Conclusion Significant increases of rotatory instability were seen on release of the dMCL, and then further increased after release of the POL. Surgical approach of retaining the dMCL and POL has a possibility to improve the outcome after primary TKA.

The aim of this study is to evaluate the relationship between patellofemoral contact stress and intraoperative knee kinematic patterns after mobile bearing total knee arthroplasty (TKA). Medial osteoarthritic knees of forty-six posterior-stabilized total knee prostheses were evaluated using a computed tomography-guided navigation system. Subjects were divided into two groups based on intraoperative knee kinematic patterns: the medial pivot group (n=19) and the non-medial pivot group (n=27). Mean intraoperative patello-femoral contact stress was significantly lower in the medial pivot group than in the non-medial pivot group (1.7MPa vs. 3.2MPa, P

The aim of this study was to evaluate the relationship between clinical results including patient-reported outcomes and intraoperative knee kinematic patterns after total knee arthroplasty (TKA). A cross-sectional survey of forty consecutive medial osteoarthritis patients who had a primary TKA using a CT-based navigation system was conducted. Subjects were divided into two groups based on intraoperative kinematic patterns: a medial pivot group (n = 20) and a non-medial pivot group (n = 20). Subjective outcomes with the new Knee Society Score and clinical outcomes were evaluated. The functional activities, patient satisfaction and the knee flexion angle of the medial pivot group were significantly better than those of the non-medial pivot group. An intraoperative medial pivot pattern positively influences deep knee flexion and patient-reported outcomes.

The aim of this study was to clarify the risk of knee flexion contracture associated with a posterior femoral condylar offset after total knee replacement (TKR). Radiographs from 100 healthy Japanese volunteers were included in the study. We evaluated femoral component posterior offset in various implants and compared them with the normal Japanese knee. Posterior offset of the femoral condyle is up to a maximum of 4.7 times greater than that of the healthy Japanese knee in all knee implants. Excess posterior offset of the femoral condyle in TKR prostheses may cause knee joint flexion contracture due to the relative shortening of the posterior soft tissue.

The aim of this randomized prospective study was to clarify risks associated with a drain-clamping method using tranexamic acid and carbazochrome sodium sulfonate hydrate after total knee arthroplasty (TKA). Subjects comprised 100 patients scheduled to undergo TKA, randomized into 2 groups: 50 patients received the drain-clamping method using tranexamic acid and carbazochrome sodium sulfonate hydrate and 50 patients received drain-clamping with saline. Although bleeding volume was significantly lower in the group with tranexamic acid and carbazochrome sodium sulfonate hydrate, risk of asymptomatic deep venous thrombosis as detected by ultrasonography was comparable between groups. Tranexamic acid and carbazochrome sodium sulfonate hydrate in the drain-clamping method help reduce bleeding after TKA without increasing the risk of deep venous thrombosis.

Controversies exist in clinical study concerning the effect of rotating platform on patellar tracking. The aim of this in vivo study was to compare tibial rotation, patellar tracking, and patellofemoral contact stress in mobile and fixed-bearing platform intraoperatively in the same knee. Sixty-six knees of posterior-stabilized total knee prostheses were evaluated using a computed tomography-guided navigation system. Medial shift and lateral tilt of patella were significantly smaller in mobile knee. Averaged maximum contact stress was significantly smaller in mobile knee than fixed knee. However, tibial rotation during flexion has no significant difference. This study showed that mobile platform total knee arthroplasty significantly improved patellar tracking and decreased patellofemoral contact stress.

We present the results of total hip arthroplasty using S-ROM (Depuy, Warsaw, Ind) prosthesis combined with corrective femoral transverse osteotomy for hips with proximal femoral deformity. Fourteen hips were followed up for a mean of 61 months (range, 36-95 months), with a mean age at surgery of 55 years (range, 44-69 years). The average intraoperative blood loss was 638 mL, and the average operative time was 136 minutes. The average Harris Hip Score increased from 38.0 (range, 15.0-55.7) preoperatively to 82.0 (range, 34.6-92.7) at the latest follow-up. All the hips except for 1 acquired union of osteotomy and bone ingrowth. S-ROM modular stem, which gives sufficient rotational stability at both proximal and distal parts of the osteotomy, is useful for total hip arthroplasty combined with corrective femoral transverse osteotomy.