A Prospective Clinical and Magnetic Resonance Imaging-Based Follow-up Beyond 10 Years After Arthroscopic Matrix-Induced Autologous Chondrocyte Implantation

Background: Long-term studies are emerging reporting encouraging outcomes after matrix-induced autologous chondrocyte implantation (MACI). While MACI has historically been undertaken via open arthrotomy, arthroscopic techniques have been reported. However, longer term clinical outcomes and/or graft survivorship after arthroscopically performed MACI are yet to be reported. Purpose: To present longer term clinical and radiological outcomes in patients after MACI performed arthroscopically on the femoral condyles. Study Design: Case series; Level of evidence, 4. Methods: A total of 45 patients were prospectively recruited and underwent arthroscopically performed MACI to the medial femoral condyle (MFC; n = 31; defect size, 1.0-7.7 cm 2 ) or lateral femoral condyle (LFC; n = 14; defect size, 1.5-5.0 cm 2 ). Outcomes were collected before surgery and at 1, 2, and 5 years as well as at a mean of 13.6 years (range, 11-17 years) after surgery. These included scores for a variety of patient-reported outcome measures (PROMs) including the Knee Injury and Osteoarthritis Outcome Score, Lysholm Knee Score, Tegner Activity Scale, and patient satisfaction. Active knee range of motion as well as peak isokinetic knee extensor and flexor strength were assessed, while magnetic resonance imaging (MRI) was undertaken. The Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) scoring tool was employed to grade relevant graft parameters, along with an overall MRI composite score. Results: A significant improvement ( P < .0001) was observed on most PROMs, with no differences between patients undergoing MACI to the MFC or LFC. Of those assessed at final follow-up, 100% were satisfied with the ability of MACI to relieve their knee pain, while 95% were satisfied with their ability to participate in sport. Active knee flexion range of motion significantly improved ( P < .0001), as did the knee extensor strength limb symmetry index ( P < .0001), although no differences were observed based on graft location. Despite encouraging MRI-based scores at final follow-up, a significant deterioration over time was observed for graft infill ( P = .040), border integration ( P = .026), surface contour ( P = .012), tissue structure ( P = .007), and the overall MRI composite score ( P = .029), largely as a result of mean changes from 5 years to final follow-up. Apart from better scores for subchondral lamina over the period in LFC grafts, no MRI-based differences were observed based on graft location. One patient demonstrated a graft bed devoid of repair tissue, indicating graft failure, and combined with one additional patient who progressed to total knee arthroplasty, a failure rate of 4.4% was observed. Conclusion: MACI performed via an arthroscopic approach provided sound clinical outcomes, patient satisfaction, and graft survivorship at a mean 13.6 years after surgery.