Background: Intra-articular platelet-rich plasma (PRP) injections have been proposed for the treatment of knee osteoarthritis (OA); however, their effectiveness in Japanese patients remains unclear. Purpose: To investigate whether 3 intra-articular injections of leukocyte-poor PRP (LP-PRP) improve symptoms and joint function in symptomatic Japanese patients with mild to moderate knee OA. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: Of 72 patients screened, 30 were included and randomized to receive LP-PRP (n = 15) or saline (placebo; n = 15) injections between March 2019 and February 2023. Patients attended a screening visit and 3 treatment visits at 1 week apart, followed by 3 follow-up visits (at 4, 12, and 24 weeks) after the initial treatment visit. The primary efficacy outcome measure was the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, whereas the secondary efficacy outcome measures were the proportion of patients showing a visual analog scale (VAS) improvement of ≥50%. Magnetic resonance imaging was performed to evaluate joint effusion and bone marrow lesions using the Whole-Organ Magnetic Resonance Imaging Score. Patients were followed for 24 weeks. Results: Patients in the PRP group (mean age, 65.9 years) had a mean hip-knee-ankle angle of 5.1°, with 7 and 8 patients demonstrating Kellgren-Lawrence grade 2 and 3 knee OA, respectively. Patients in the placebo group (mean age, 67.9 years) had a mean hip-knee-ankle angle of 3.8°, with 6 and 9 patients showing Kellgren-Lawrence grade 2 and 3 knee OA, respectively. No significant differences were identified in any baseline factors. The percentage change in Western Ontario and McMaster Universities Osteoarthritis Index scores from baseline to 24 weeks was significantly different (P= .032) between the PRP (median, 75.9%; quantile 1 [Q1], 49.6; quantile 3 [Q3], 94.1]) and placebo (median, 27.7%; Q1, –9.4; Q3, 80.9]) groups. Overall, 73.3% and 28.6% of the PRP group and placebo group, respectively, exhibited an improvement in visual analog scale scores of ≥50%, with a significant improvement observed in the PRP group ( P = .027). Changes in bone marrow lesions from baseline to 24 weeks, as assessed on magnetic resonance imaging, significantly differed between groups ( P = .017), with no significant differences in other secondary endpoints. Conclusion: In Japanese patients with knee OA, 3 intra-articular LP-PRP injections led to clinical improvements at 24-week follow-up and significant functional improvements and pain relief after 24 weeks.

To provide normal knee function, a total knee arthroplasty (TKA) implant with an anatomic surface shape and an adequate sagittal position has been developed. However, it is unclear how this modern implant influences knee joint kinetics and muscle activation during a gait. Therefore, we evaluated this modern TKA prosthesis and compared it with a conventional TKA prosthesis for gait analysis in terms of kinetics and muscle activation. Subjects were patients (>60 years of age) with knee osteoarthritis who had undergone unilateral TKA. Twelve patients received the modern TKA prosthesis (group modern), and the other 12 patients received a conventional TKA prosthesis (group conventional). The subjects underwent motion capture analyses with a force plate, and kinematic and kinetic data were acquired from a 10-m gait test. Electromyography data of 6 lower limb muscles were simultaneously collected during the gait test. The 2 groups were compared using unpaired t-tests. In group modern, gait speed was faster, step length was longer, and the knee flexion angle during the initial stance phase was larger. Furthermore, in group modern, the maximum knee extension moment was higher; however, the quadriceps muscle activity tended to be lower than that in group conventional. Gait characteristics of group modern were more like a normal gait, and knee joint extension moments were greater. This finding indicates that the quadriceps muscles can be more effectively activated, and the anterior stability function of the anterior cruciate ligament may be reproduced with the shape of the modern implant.

Purpose: The adjustable loop cortical suspension device (ALD) is a useful femoral fixation device in anterior cruciate ligament (ACL) reconstructions, but the possibility of loosening has been suggested. The purpose of this study was to evaluate the elongation of an adjustable loop and the position of the hamstring graft inside the femoral socket.Methods: The subjects were 33 patients who underwent ACL reconstruction with a hamstring tendon. The graft was fixed using ALD and completely filled the femoral socket. Magnetic resonance images were taken one week and one year after the operation. The loop length, femoral socket length, and graft length inside the socket were measured and statistically compared with the clinical outcomes.Results: The loop length one week after surgery was 18.9 ± 4.4 mm, and 1 year after surgery was 19.9 ± 4.5 mm (P < 0.001). The gap between the top of the graft and femoral socket was 0.9 ± 1.8 mm one week after surgery and 1.3 ± 1.7 mm one year after surgery (P = 0.259). At one week post‐operation, a gap was found in nine patients (27.3%). The loop length and gap did not strongly correlate with clinical findings.Conclusion: ACL reconstruction using ALD showed a gap between the graft and femoral socket at the one week post‐operation mark in 27.3% of participants. One year after the surgery, there were cases where the gap increased and/or decreased, but the elongation of the loop was 1 mm on average. Our findings suggest that ALD is clinically safe to use; however, has the possibility of initial loop elongation and non‐uniform changes.Level of evidence: IV.

The sit-to-stand (STS) movement is important in improving satisfaction after total knee arthroplasty (TKA). Reports on motion analysis using a combination of motion capture systems, force plates, and surface electromyography after TKA are limited. We aimed to compare the STS movement of patients aged over 60 who underwent modern and conventional TKA with more than 6 months of postoperative follow-up. Ten patients underwent surgery with a modern implant (Group I: Smith and Nephew JOURNEY II, Memphis, TN, USA), and ten with a conventional implant (Group II: Smith and Nephew LEGION, Memphis, TN, USA). STS movement kinematics and kinetic data were measured by synchronising a motion capture system with a force plate. Surface electromyography was used to measure the muscle activity. STS time was shorter in Group I than in Group II. Maximum knee-extension angular velocity and maximum knee-extension moment were greater in Group I than in Group II. Electromyography revealed that Group I tended to have less activity in the quadriceps femoris than Group II. Group II had a greater hip-extension moment and vertical ground reaction force, and the hip joint seemed to compensate for knee function. Group I possibly used the quadriceps muscle more effectively, due to the implant shape.