LAUSR

Objectives: The complex environment and the extreme stresses of the patellofemoral joint make chondral defects a challenge to treat. Autologous chondrocyte implantation (ACI) and osteochondral allograft transplantation (OCA) have been reported as case series in the patellofemoral joint with mixed results. This study compared the clinical outcomes for ACI and OCA treatments for patellofemoral chondral defects at our institution. Methods: We reviewed all consecutive patients undergoing ACI and OCA at a single institution for the treatment of isolated patellofemoral cartilage defects. Treatment type was based on surgeon preference. Medical records were examined for patient demographic, lesion specific data, complications, re-operations and failures (graft delamination requiring surgery, revision cartilage repair or conversion to arthroplasty). Clinical outcomes included International Knee Documentation Committee (IKDC) and Short Form 12 health survey (SF-12) scores. Mean follow up was 5.2 years (range, 3.1-7.5 years). Results: There were 30 patients: 19 in the ACI group and 11 in the OCA group with a mean age of 33 (15-48) and 25.5 (16-55) respectively (p=0.12). Etiology in the ACI group was 63%(n=12) patellar instability, 21%(n=4) post-traumatic osteoarthritis, 10%(n=2) primary osteoarthritis and 5%(n=1) osteochondritis dissecans, whereas it was more evenly distributed in the OCA group (27%, 27%, 19% and 27% respectively). Lesions in the ACI group were either Fulkerson type III (84% (n=16), medial patellar facet) or type IV (16%(n=3), pan-patellar). In the OCA group, lesions varied between type 1 (9%(n=1)), type II (27%(n=3)), type III (9%(n=1)) and type IV (54%(n=6)). The mean lesion size was similar between the two groups (OCA 3.1 cm2 ±1.1 vs. ACI 3.4 cm2 ±2.4, p=0.7) with more bipolar lesions in the OCA group (45%(n=5) vs.11%(n=2), p=0.038). Failures (requiring revision or replacement surgery), were significantly more common in OCA at 36% (n=4) compared to 5.3% (n=1) in ACI patients (p=0.04), one of which was bipolar in the former group. Re-operation was performed in 27%(n=3) OCA patients (each for adhesiolysis) and in 21%(n=4) ACI patients (2 manipulation under anesthesia, 1 adhesiolysis and 1 graft debridement for overgrowth) (p=0.3). There were no significant differences between the OCA and ACI groups in IKDC (60.7 vs. 74, p=0.08) and SF-12 scores (43.5 vs 43.7, p=0.43). Conclusion: Compared to ACI, OCA had significantly more failures for patellofemoral chondral defects at short to mid-term follow-up. This may relate to differences in the etiology and lesion locations between the two groups. Despite these findings, both groups had similar complication rates and functional outcome scores.