Comparable Outcomes Between Autologous Chondrocyte Implantation and Osteochondral Allograft Transplantation in the Setting of Patellar Realignment

Purpose: To determine clinical and functional outcomes in patients treated with autologous chondrocyte implantation (ACI) or osteochondral allograft (OCA) transplantation for chondral defects secondary to patellar instability with concomitant medial patellofemoral ligament (MPFL) reconstruction and tibial tubercle osteotomy (TTO) for patellar realignment. Methods: A retrospective review identified patients who underwent ACI or OCA transplantation with concomitant MPFL reconstruction and TTO. Patients were excluded if they did not have concomitant MPFL reconstruction and TTO, had the presence of other intra-articular pathologies, or failed to complete postoperative subjective outcome evaluations at a minimum of 2 years following surgery. Subjective outcome measures included the Knee injury and Osteoarthritis Outcome Score for Joint Replacement, International Knee Documentation Committee evaluation, and 12-item Short Form Health Survey physical scores, collected a minimum of 2 years after surgery. Defect location, size, complications, and rate of subsequent surgery were determined. Results: Eighteen total patients were included in this study. The ACI cohort included 11 patients with 13 total defects that were treated with ACI. The OCA cohort included 7 patients with 10 total defects that were treated with OCA. This was due to a number of patients in either group having multiple cartilage defects. Twenty-three total chondral defects were compared to analyze clinical and functional outcomes following surgical correction (ACI: n = 13, OCA: n = 10). Five defects were noted on the femoral condyle and 18 on the patellar facets/central ridge. Defects were comparable between groups, including size measured during index arthroscopy (ACI = 3.34 cm2 [95% CI, 2.3-4.4 cm2] vs OCA = 4.03 cm2 [95% CI, 3.1-5.0 cm2]; P = .351), Outerbridge classification (ACI = 54.8% grade 4 vs OCA = 60.0% grade 4; P >= .999), and Area Measurement and Depth Underlying Structures score (ACI = 47.1 vs OCA = 58.6; P = .298). Postoperative outcomes were comparable, including revision rate (ACI = 15.4% vs OCA = 10.0%; P >= .999) and 2-year International Knee Documentation Committee scores (ACI= 74.2 [95% CI, 65.2-83.2] vs OCA = 51.2 [95% CI, 30.3-72.1]; P= .077). ACI did have significantly higher 2-year Knee injury and Osteoarthritis Outcome Score for Joint Replacement (85.1 [95% CI, 76.9-93.3] vs 63.7 [95% CI, 49.1-78.3]; P = .031) and 12-item Short Form Health Survey scores (54.1 [95% CI, 52.0-56.2] vs 42.6 [95% CI, 35.8-49.4]; P = .007) compared to OCA. Conclusions: ACI or OCA transplantation for chondral defects with concomitant MPFL reconstruction and TTO can be safely performed in an outpatient setting with functional and clinical outcomes being comparable. Level of Evidence: Level III, retrospective case series study.