Prospective Evaluation of Autologous Chondrocyte Implantation Procedure: Minimum Seven-Year Follow-Up (SS-26)

Introduction Autologous chondrocyte implantation (ACI) shows promising short and intermediate-term results for the treatment of full thickness cartilage defects in the knee. However, the long-term outcomes of the procedure are not well described. The purpose of this study is to report the clinical outcomes following ACI from a single orthopedic surgeon at a minimum of 7 years' follow-up using validated outcome scores and physical examination. Methods 29 patients were contacted at minimum 7 years postoperatively after a retrospective review between 1998 and 2003. Patients without preoperative data and reliable contact information were excluded from the study. IKDC, Tegner-Lysholm, KOOS, SF-12, verified outcome measures were collected both preoperatively and postoperatively. Preoperative data was compared to 2-, 4-, and 7-year postoperative outcomes to assess the durability of the implant over time. Pre-specified subgroup analysis of subjective scores was also assessed. In order to obtain objective data, all 29 patients enrolled in the study were recruited to undergo a 7-year postoperative physical examination by a sports medicine fellow. Results The mean patient follow-up was 8.36 years. All lesions were grade-IV, with a mean lesion size of 3.50 cm 2 . Mean IKDC, Lysholm, SF-12 physical/mental, all KOOS (pain, symptoms, activities of daily living, sports, quality of life) scores improved significantly (p 2 ) (n=4) reported significantly lower 7-year postoperative scores on Tegner-Lysholm and KOOS-ADL measures than non-obese patients (BMI 2 ) (n=25), and patients undergoing concomitant meniscal transplant (n=5) showed significant improvements in IKDC scores. Physical exam (n=16) findings were insignificant except for crepitus noted in 8 patients and mild focal chondral tenderness was also noted in 8 patients. Conclusion Validated subjective scores demonstrated significant and sustained improvement in patients at a 2-, 4-, and 7-year follow-up. Similarly, objective data reported decreased levels of tenderness and increased functional ability. The data supports that ACI is a durable long-term treatment for patients with symptomatic full-thickness cartilage lesions and can reduce pain, increase range of motion, and improve joint function. Subgroup analysis suggests a possible connection between meniscal stability and long-term ACI efficacy as well as obesity as an indicator of poorer prognosis. An advantage of this study compared to other long-term follow up studies is that we reduce confounding due to differing surgical performance by collecting data from patients treated by a single surgeon. Like similar long-term studies, limitations include a small patient population and lack of a control group. The results of an ACI in patients who present with symptomatic chondral defects remain durable at a minimum of 7-year follow-up with persistent, high levels of patient satisfaction.