Autologous Chondrocyte Implantation for Bipolar Chondral Lesions in the Patellofemoral Compartment: Clinical Outcomes at a Mean 9 Years' Follow-up

Background: Treating bipolar chondral lesions in the patellofemoral (PF) compartment is a challenging problem. There are few reports available on the treatment of bipolar chondral lesions in the PF compartment. Purpose: To evaluate the clinical outcomes and graft survivorship after autologous chondrocyte implantation (ACI) for the treatment of bipolar chondral lesions in the PF compartment. Study Design: Case series; Level of evidence, 4. Methods: The authors evaluated 58 patients who had ACI by a single surgeon for the treatment of symptomatic bipolar chondral lesions in the PF compartment between November 1995 and June 2014. All 58 patients (60 knees; mean age, 36.6 years) were included with a minimum 2-year follow-up. The mean +/- SD sizes of the patellar and trochlear lesions were 5.6 +/- 2.7 cm(2) and 4.2 +/- 2.8 cm(2), respectively. Forty-two patients had osteotomy, as they had PF lateral maltracking, patellar instability, or tibiofemoral malalignment. Patients were evaluated with the modified Cincinnati Knee Rating Scale, Western Ontario and McMaster Universities Osteoarthritis Index, visual analog scale, the 36-Item Short Form Health Survey, and a patient satisfaction survey. Radiographs were evaluated with the Iwano classification. Results: Overall, the survival rates were 83% and 79% at 5 and 10 years, respectively. Of the 49 (82%) knees with retained grafts, all functional scores significantly improved postoperatively with a very high satisfaction rate (88%) at a mean 8.8 +/- 4.2 years after ACI (range, 2-16 years). At the most recent follow-up, 28 of 49 successful knees were radiographically assessed (mean, 4.9 years; range, 2-17 years), with no increase of the Iwano classification in 26 knees. Outcomes for 11 patients were considered failures at a mean 2.9 years. Forty-two knees (70%) required a mean 1.0 subsequent surgical procedure. The primary reasons for chondroplasty were hypertrophy of the ACI graft (17; periosteum in 14, collagen membrane in 3), delamination of the ACI graft (5; periosteum in 4, collagen membrane in 1), and new chondral lesions (3). The best survival rates were observed among patients who underwent ACI with concomitant tibial tubercle osteotomy (TTO) as the first procedure without previous failed TTO and/or marrow stimulation technique (91% at 5 and 10 years), while the worst survival rates were observed among patients who had previous marrow stimulation (43% at 5 and 10 years). Conclusion: Results demonstrated that ACI with concomitant osteotomy, when it is necessary for the treatment of bipolar/kissing lesions in the PF compartments, gives significant improvement in pain and function, with good survival rates at 5 and 10 years (83% and 79%, respectively). The high patient satisfaction rate is encouraging, and a high survival rate can be expected when ACI with a concomitant TTO is performed at the initial surgery for this difficult condition.