Survival Analysis of Revision Autologous Chondrocyte Implantation for Failed ACI

Autologous chondrocyte implantation (ACI) provides a successful outcome for treating articular cartilage lesions. However, there have been very few reports on the clinical outcomes of revision ACI for failed ACI.

To evaluate clinical outcomes in patients who underwent revision ACI of the knee for failure of an initial ACI and to determine the factors affecting the survival rate.

Case series; Level of evidence, 4.

A review of a prospectively collected data set was performed from patients who underwent revision ACI of the knee for failure of an initial ACI between 1995 and 2014 by a single surgeon. The authors evaluated 53 patients (53 knees; mean age, 38 years) over a mean 11.2-year follow-up (range, 2-20). A total of 62 cartilage lesions were treated for failed graft lesions after an initial ACI, and 31 new cartilage lesions were treated at revision ACI, as there was progression of disease. Overall, 93 cartilage lesions (mean, 1.8 lesions per knee) with a total surface area of 7.4 cm² (range, 2.5-18 cm²) per knee were treated at revision ACI. Survival analysis was performed with the Kaplan-Meier method, with ACI graft failure or conversion to a prosthetic arthroplasty as the endpoint. The modified Cincinnati Knee Rating Scale, Western Ontario and McMaster Universities Osteoarthritis Index, visual analog scale, and 36-Item Short Form Health Survey were used to evaluate clinical outcomes. Patients also self-reported knee function and satisfaction. Standard radiographs were evaluated with Kellgren-Lawrence grades.

Survival rates were 71% and 53% at 5 and 10 years, respectively. Survival subanalysis revealed a trend that patients without previous cartilage repair procedures before an initial ACI had better survival rates than those with such procedures (81% vs 62% at 5 years, 64% vs 42% at 10 years, P = .0958). Patients with retained grafts showed significant improvement in pain and function, with a high level of satisfaction. At a mean 5.1 years postoperatively, 18 of 27 successful knees were radiographically assessed with no significant osteoarthritis progression. Outcomes for 26 patients were considered failures (mean, 4.9 years postoperatively), in which 15 patients had prosthetic arthroplasty (mean, 4.6 years) and the other 11 patients had revision cartilage repair (mean, 5.4 years) and thus could maintain their native knees.

Results of revision ACI for patients who failed ACI showed acceptable clinical outcomes. Revision ACI may be an option for young patients after failed initial ACI, particularly patients without previous cartilage repair procedures and those who desire to maintain their native knees.