A RANDOMIZED CONTROLLED TRIAL EVALUATING AN ACCELERATED WEIGHT-BEARING REHABILITATION PATHWAY AFTER MATRIX-INDUCED AUTOLOGOUS CHONDROCYTE IMPLANTATION FOR SYMPTOMATIC KNEE CARTILAGE DEFECTS

Matrix-induced autologous chondrocyte implantation (MACI) has demonstrated encouraging outcomes in treating symptomatic knee cartilage lesions which, if untreated, can progress toward early osteoarthritis. Rehabilitation is imperative to optimize outcome, though has been traditionally conservative. This study investigated the long-term outcomes of an accelerated return to full weight bearing (WB) after MACI. This prospective randomized controlled trial (RCT) allocated 35 patients (37 knees) to a 6-week (n=18) or 8-week (n=19) return to full WB after MACI. Patients were evaluated pre-operatively and at 1, 2, 5 and ≥10 years, via patient-reported outcome measures (PROMs) including the Knee Osteoarthritis Outcome Score (KOOS). Single limb hop capacity and peak knee extensor and flexor torque were assessed, with limb symmetry indices (LSIs) calculated. Magnetic resonance imaging (MRI) evaluated repair tissue, while a validated MRI composite graft score was calculated. While the 6-week WB group reported significantly better 1-year KOOS Quality of Life scores, no other differences (p>0.05) in PROMs existed. The peak knee extensor torque LSI significantly improved (p<0.0001) over time, with mean LSIs of 100.8 (6-week) and 99.1 (8-week) at ≥10 years. No group differences (p>0.05) were observed in hop LSIs. A non-significant decline (p>0.05) was observed for the MRI composite score from 1-year to final ≥10-year review and, apart from a significant group effect (p=0.028) for graft tissue intensity in favor of the 6-week group suggesting repair tissue more reflective of native cartilage, no other MRI-based differences (p>0.05) existed. At ≥10-years, no grafts on MRI had failed, though 3 patients (6-week n=1, 8-week n=2) had progressed toward knee arthroplasty. The 6-week accelerated rehabilitation program provided comparable clinical and MRI-based outcomes beyond 10 years post-surgery, without jeopardizing the graft.