A prospective, randomised study comparing two techniques of autologous chondrocyte implantation for osteochondral defects in the knee: Periosteum covered versus type I/III collagen covered

INTRODUCTION: The results for autologous chondrocyte implantation (ACI) in the treatment of full thickness chondral defects in the knee are encouraging. At present two techniques have been described to retain the chondrocyte suspension within the defect. The first involves using a periosteal cover (ACI-P) and the second involves using a type I/III collagen membrane (ACI-C). To the authors knowledge there are no comparative studies of these two techniques in the current literature. We have therefore undertaken such a study to establish if there is a difference between the 2 techniques based on a clinical and arthroscopic assessment. METHODS: A total of 68 patients with a mean age of 30.52 years with symptomatic articular cartilage defects were randomised to have either ACI-P (33 patients) or ACI-C (35 patients). The mean defect size was 4.54 cm2. All patients were followed up at 24 months. RESULTS: A clinical and functional assessment showed that 74% of patients had a good or excellent result following the ACI-C compared with 67% after the ACI-P at 2 years. Arthroscopy at 1 year also demonstrated similar results for both techniques. However, 36.4% of the ACI-P grafts required shaving for hypertrophy compared with none for the ACI-C grafts at 1 year. DISCUSSION: This study has shown no statistical difference between the clinical outcome of ACI-C versus ACI-P at 2 years. A significant number of patients who had the ACI-P required shaving of a hypertrophied graft. We conclude that there is no advantage in using periosteum as a cover for retaining chondrocytes within an osteochondral defect; as a result we advocate the use of an alternative cover such as a manufactured type I/III collagen membrane.