Autologous Chondrocyte Implantation for Bipolar Chondral Lesions in the Tibiofemoral Compartment

Background: Treating bipolar chondral lesions in the tibiofemoral (TF) compartment with cartilage repair procedures is challenging, and a suitable treatment remains unclear. Purpose: To evaluate clinical outcomes after autologous chondrocyte implantation (ACI) for the treatment of bipolar chondral lesions in the TF compartment. Study Design: Case series; Level of evidence, 4. Methods: We evaluated 57 patients who underwent ACI for the treatment of symptomatic bipolar chondral lesions in the TF compartment by a single surgeon between October 1995 and June 2014. One patient did not return for follow-up. Thus, 56 patients (58 knees) were included with a minimum of 2 years’ follow-up. A mean of 3.1 lesions per knee were treated, representing a mean total surface area of 16.1 cm 2 (range, 3.2-44.5 cm 2 ) per knee. Bipolar lesions were present in the medial compartment (32 knees) and in the lateral compartment (26 knees). Patients were evaluated with the modified Cincinnati Knee Rating Scale, visual analog scale for pain, Western Ontario and McMaster Universities Osteoarthritis Index, and Short Form–36. Patients also answered questions regarding self-rated knee function and satisfaction with the procedure. Standard radiographs were evaluated with the Kellgren-Lawrence grading system. Results: The survival rate was 80% at 5 years and 76% at 10 years. A significantly better survival rate was found in patients with the use of a collagen membrane than periosteum (97% vs 61% at 5 years, respectively; P = .0014). Of 46 knees with retained grafts, all functional scores significantly improved postoperatively, with a very high satisfaction rate (91%) at a mean of 8.3 ± 5.1 years (range, 2-20 years) after ACI. At last follow-up, 24 of 46 successful knees were radiographically assessed (mean, 5.5 ± 4.0 years [range, 2.0-18.7 years]) and showed no significant osteoarthritis progression ( P = .3173). Outcomes for 12 patients were considered as failures at a mean of 4.1 years. Of these, 9 patients were converted to partial or total knee arthroplasty at a mean of 4.4 years. Two patients underwent revision ACI at 5 and 17 months. The other 1 patient did not require revision surgery. Conclusion: Our study showed that ACI for the treatment of bipolar chondral lesions in the TF compartment provided successful clinical outcomes in patients with retained grafts and possibly prevented or delayed osteoarthritis progression at midterm to long-term follow-up. A collagen membrane is more encouraging than periosteum for bipolar lesions in the TF compartment. While addressing the predisposing factors affecting cartilage repair, ACI could be an adequate salvage procedure for bipolar chondral lesions in the TF compartment for the relatively young arthritic patient who wishes to avoid arthroplasty.