Autologous Chondrocyte Implantation in the Adolescent Knee

Background: Autologous chondrocyte implantation (ACI) has been shown to have favorable results in the treatment of symptomatic chondral and osteochondral lesions. However, there are few reports on the outcomes of this technique in adolescents. Purpose: The aim of this study was to assess pain relief and functional outcome in adolescents undergoing ACI. Study Design: Case series; Level of evidence, 4. Methods: Thirty-five adolescent patients undergoing ACI or matrix-assisted chondrocyte implantation (MACI) were identified from a larger cohort. Four patients were lost to follow-up, leaving 31 patients (24 ACI, 7 MACI). The mean age was 16.3 years (range, 14-18 years) with a mean follow-up of 66.3 months (range, 12-126 months). There were 22 male and 9 female patients. All patients were symptomatic; 30 had isolated lesions and 1 had multiple lesions. Patients were assessed preoperatively and postoperatively using the visual analog scale (VAS) score for pain, the Bentley Functional Rating Score, and the Modified Cincinnati Rating System. At 1 year postoperatively, patients were recalled for a diagnostic biopsy, which was successfully attained in 21 patients. Results: The mean pain scores improved from 5 preoperatively to 1 postoperatively. The Bentley Functional Rating Score improved from 3 to 0, while the Modified Cincinnati Rating System improved from 48 preoperatively to 92 postoperatively with 84% of patients achieving excellent or good results. All postoperative scores exhibited significant improvement from preoperative scores. One patient underwent graft hypertrophy and 1 patient's graft failed and was revised. Biopsy results revealed hyaline cartilage in 24% of cases, mixed fibro/hyaline cartilage in 19%, and fibrocartilage in 57%. Conclusion: Results show that, in this particular group who received ACI, patients experienced a reduction in pain and significant improvement in postoperative function after ACI or MACI. The authors believe that ACI is appropriate in the management of carefully selected adolescents with symptomatic chondral and osteochondral defects.