Is Delayed Weightbearing After Matrix-Associated Autologous Chondrocyte Implantation in the Knee Associated With Better Outcomes? A Systematic Review of Randomized Controlled Trials

BACKGROUND: Proper rehabilitation after matrix-associated autologous chondrocyte implantation (MACI) is essential to restore a patient’s normal function without overloading the repair site. PURPOSE: To evaluate the current literature to assess clinical outcomes of MACI in the knee based on postoperative rehabilitation protocols, namely, the time to return to full weightbearing (WB). STUDY DESIGN: Systematic review; Level of evidence, 1. METHODS: A systematic review was performed to locate studies of level 1 evidence comparing the outcomes of patients who underwent MACI with a 6-week, 8-week, or 10/11-week time period to return to full WB. Patient-reported outcomes assessed included the Knee injury and Osteoarthritis Outcome Score (KOOS), Tegner activity scale, Short Form Health Survey–36 (SF-36), and visual analog scale (VAS) for pain frequency and severity. RESULTS: Seven studies met the inclusion criteria, including a total of 136 patients (138 lesions) who underwent MACI. Treatment failure had occurred in 0.0% of patients in the 6-week group, 7.5% in the 8-week group, and 8.3% in the 10/11-week group at a mean follow-up of 2.5 years (P = .46). KOOS, SF-36, and VAS scores in each group improved significantly from preoperatively to follow-up (P < .001). CONCLUSION: Patients undergoing MACI in the knee can be expected to experience improvement in clinical outcomes with the rehabilitation protocols outlined in this work. No significant differences were seen in failure rates based on the time to return to full WB.