Biomechanical adaptations in hip and ankle following autologous bone grafting combined with spheroid-based matrix-induced autologous chondrocyte implantation for osteochondral defects of the knee

Introduction Altered knee gait mechanics have been reported in patients treated with matrix-induced autologous chondrocyte implantation combined with autologous bone grafting (MABCI) for osteochondral defects of the knee. Objectives The aim of this study was to investigate whether altered gait mechanics following MABCI extend to adjacent joints by analyzing hip and ankle gait biomechanics in comparison with matched controls. Methods Gait data from 31 patients (19 males, 12 females; mean defect size 4.2 ± 2.5 cm²; mean follow-up: 43.7 ± 22.7 months) were analyzed. Hip and ankle kinematics were assessed using 3D treadmill-based gait analysis. Data were compared with a matched healthy control group. Subgroup analysis was performed based on defect size (<4 cm² vs ≥4 cm²). Results Operated limbs showed a significantly steeper slope of hip extension during the loading response phase of the gait cycle compared with contralateral limbs (51.8 ± 13.7% vs 39.4 ± 16.2%, P = .002) and controls (22.6 ± 11.9%, P < .001). During mid-stance, the slope of hip extension was significantly flatter in operated limbs (72.0 ± 11.9%) compared with contralateral (77.3 ± 12.5%, P < .002) and control limbs (90.8 ± 12.7%, P < .001). Operated limbs demonstrated greater maximum ankle dorsiflexion than contralateral limbs (13.2 ± 3.7° vs 11.9 ± 3.9°, P = .005). Patients with larger defects had a significantly greater hip extension (−13.4 ± 5.5° vs −6.3 ± 7.7°, P = .007) and a tendency toward steeper early hip extension slope during loading response phase in operated limbs (55.8 ± 16.1% vs 48.5 ± 10.8%, P = .223). Conclusions Patients treated with MABCI for osteochondral knee defects show significant postoperative gait alterations at the hip and ankle, presumably as adaptations to persistent knee dysfunction. These findings suggest that rehabilitation protocols should also address adjacent joint function to facilitate the restoration of physiological movement patterns.