The stability of outcomes of cancellous autografts with acellular membrane for extended osteochondritis of the knee. Outcomes for 22 AMIC® grafts at an average follow-up of 4 years

OBJECTIVES: Loss of osteochondral substances resulting from osteochondritis dissecans (OCD) of the knee are arthrogenic in the long term. When they exceed 2 cm(2), the Autologous Matrix Induced Chondrogenesis (AMIC®) technique is one of the methods used in France. The objective of this study was to evaluate the medium-term results of the AMIC® technique. METHODS: This was a consecutive, prospective, single-center, single-operator series of 22 patients (13 men, 9 women, mean age 28 years (15-51)) treated by AMIC® (spongy bone graft + sutured collagen membrane) between September 2011 and November 2016. Previous surgery had been performed on 17 patients. According to the ICRS classification, the lesion was stage IV in 21 cases and stage III in 1 case. The sites were: condylar: 19 cases, patellar: 2 cases and trochlear: 1 case. The mean surface area was 3.6 cm(2) (2-8) and the depth was 0.5 mm (0.4-0.8). All the patients were functionally assessed by an independent examiner using validated functional scores for these indications (KOOS, subjective IKDC). Student’s T tests were used. RESULTS: At a mean follow-up of 4 years (minimum 2 years) all but 2 patients had significantly improved (In preop. IKDC: 44±14 and KOOS: 56±17). In these 2 cases, the postoperative scores remained unchanged over the years: one patient had had several surgeries before the graft and a 51-year-old female patient had an extensive lesion of 6.9 cm(2). The mean IKDC and KOOS scores were 73±18 and 78±15 and then 77±16 and 81±14 respectively, at 1 and 4 years (p> 0.05 for IKDC and KOOS). Regrettably there were 2 complications: 1 arthrolysis 1 year after surgery and 1 algodystrophy. CONCLUSION: Few techniques are available in France for extensive symptomatic osteochondral lesions. AMIC® is a reliable, one-step, reproducible, inexpensive technique for loss of substance due to OCD with stable results as of 1 year after surgery.