Clinical follow-up study of autologous chondrocyte implantation of the knee

Context. Symptomatic chondral defects in the knee joint pose a difficult management issue for orthopedists and patients. The problem is compounded by the poor regenerative capacity of adult articular cartilage, and the commonly held belief that chondral injuries eventually progress to osteoarthritis. The treatment of focal articular cartilage defects in the knee joint by ACI is a fairly new technique. It is a technique indicated for a symptomatic weight -bearing chondral defect of the articular surface of the knee joint in a physiologically young patient who has failed conservative non-surgical and surgical measures. Objective. The purpose of this study is twofold: 1) to demonstrate the effectiveness of autologous chondrocyte implantation of the knee, through a retrospective review and clinical follow-up assessment of patients who received ACI treatment and 2) a pilot study to assess the physiology and homeostasis of the subchondral bone adjacent to the treated articular cartilage defect(s) by the use of limited radionuclide bone scan with single photon emission computed tomography (SPECT). Design. Two scoring systems were used to quantify the clinical status of the patients (Lysholm score and modified Cincinnati knee score). Lysholm scores and the modified Cincinnati knee rating scores were obtained at time of biopsy, as well as at follow-up visits in June 2001. In addition, a postoperative questionnaire regarding patient perception of surgical outcome was completed. Limited radionuclide bone scan with SPECT was used to assess the physiology and homeostasis of the subchondral bone. Setting. Clinical data was obtained from Dr. Jeffrey Halbrecht at the Ins.titute of Arthroscopy & Sports Medicine, California Pacific Medical Center, San Francisco, California from September 1995 to June 2001. SPECT examinations were completed at Nuclear Medicine Division, California Pacific Medical Center, San Francisco, California and assessed by Dr. Steven Bunker at the same institution. Participants. Twenty-four subjects were included in this follow-up study. Eleven were included in the pilot study. Main Outcome Measures. Clinician and patient satisfaction, as well as assessment of the physiology and homeostasis of the subchondral bone after ACI procedure. Results. Patients were followed for an average period of 26.5 months (range, 4- 63 months) after implantation with a mean age of 39.1 years. The mean Lysholm score was 43.58 before surgery and 71.42 after surgery; the modified Cincinnati knee score for overall clinician evaluation was 2.96 before surgery and 6.92 after surgery; the mean modified Cincinnati knee score for overall patient evaluation was 3.21 before surgery and 6.13 after surgery. Both scoring systems were statistically significant at a p value ofConclusions. Results of this follow-up study support prior research that ACI of the knee is a unique, and, in certain circumstances, superior alternative that successfully restore knee joint function