Introduction and aim: Early symptomatic osteoarthritis (OA) of the knee poses a difficult challenge to orthopaedic surgeons, particularly in the presence of malalignment. Most surgical options are palliative. Our aim was to assess combined high tibial osteotomy (HTO) and matrix-induced autologous chondrocyte implantation (MACI) as a curative option.

Methods Patients with localised medial compartment OA and varus malalignment were identified. Suitability for the above procedure was confirmed at arthroscopy and specimen taken for culture. HTO and MACI procedures were performed in one sitting by a single surgeon. Patients received three months rehabilitation and function was assessed preoperatively and at three-monthly intervals.

Results Twelve patients were identified: nine male; average age 46 years (27–58). Mean varus deformity was 6 degrees. Two patients also had evidence of osteochondritis dissecans, and two early patello-femoral OA. Eight patients had had previous surgery to the knee.

Eleven patients had a lateral closing wedge osteotomy; the medial opening wedge was performed in a case of leg shortening. Mean operation duration was 72 minutes (60–90). The graft was fixed with fibrin glue in all cases, and augmented with stitches or vicryl pins in five cases. Mean defect size was 6.2cm2 (2–12). There were three complications: one DVT, a haemarthrosis and a graft detachment.

Average follow-up was 16 months. MRI scans at three months show oedematous tissue at the defect sites, contrasting with the fluid filled defects seen preoperatively. Scans at one-year show hyaline-like cartilage infill with similar signal characteristics to native hyaline cartilage. Six minute walk test and knee injury and osteoarthritis outcome score indicate significantly improved functional capacity at six months and one year.

Conclusions Preliminary results suggest combined HTO and MACI is successful for young patients with early OA associated with malalignment.

Introduction and Aims: The aim of this study was to use biological, functional and radiographic evaluation to demonstrate that cultured autologous chondrocytes implanted using a type I/III collagen membrane leads to regeneration of hyaline-like articular cartilage in the knee.

Method: Approximately 70,000 knee arthroscopies are performed every year in Australia; 60% involve chondral surface defects. Three regenerative autologous cell therapy techniques have been used in Australia to treat full thickness chondral lesions:

periostial-covered autologous chondrocyte implantation (PACI);

The team at the University of Western Australia has concentrated on CACI and MACI techniques because of concerns over fibroblast formation and hypertrophy with PACI. Definitive evidence regarding the role of the membrane in enhancing chondrocyte-mediated cartilage regeneration is lacking.

Results: The series consists of a total of 71 patients who had failed previous surgical treatment prior to definitive collagen-covered ACI (32 implantations in 31 patients) or MACI (43 implantations in 40 patients). Biological, functional and radiographic evaluations were conducted pre-operatively, and post-operatively in order to determine the success of integration of implanted chondrocytes and categorise the level of restoration in knee joint function. Post-operative MRI scans at three months show oedematous tissue at the defect sites, contrasting with the fluid-filled defects seen pre-operatively. MRI scans at one, two and three years (collagen-covered) and one year (MACI) show normal cartilage signal. Apopototic test of chondrocytes before implantation showed that viability of chondrocytes was over 85% where apopototic rate of chondrocytes was less than 2%. Six-minute walk test and KOOS results indicate improved functional capacity following collagen covered and MACI.

Conclusion: Results from this clinical study indicate that the use of a type I/III collagen membrane in conjunction with ACI is a valid new approach for the treatment of chondral defects. Results from radiographic, functional and biological evaluations are encouraging. Ongoing follow-up will reveal the durability of reconstructions with CACI and MACI.