Cutting-edge design to improve cell viability in osteochondral grafts

Autologous osteochondral grafting is in widespread use for focal defects of articular cartilage. There is major concern over the nature of the tissue bridging graft elements and graft/recipient cartilage. Chondrocyte viability is thought to be an important determinant of the quality of repair. The aim of the current study was to compare the zone of death for osteochondral grafts harvested with the commercially available Acufex, and an osteotome with a specially designed cutting-edge.

The circular osteotomes were the Acufex 4.5mm MP (Smith & Nephew) and the Lissimore, which has a different cutting-tip geometry and sharpness. These implements were used to harvest osteochondral plugs from macroscopically non-degenerate human lateral condyle explants obtained from the anterior femoral cuts of knee replacement surgery. Confocal laser scanning microscopy with vital staining was used to quantify the zone of marginal chondrocyte death for the entire perimeter of the plugs.

The increase in cartilage plug diameter (reference the osteotome minimal internal diameter) was significantly greater for the Acufex (Mann-Whitney; n=5; P=0.0079), with the diameter (mm) increasing by 0.49+/-0.03 (10.9%), compared with 0.16+/-0.02 (3.3%) for the Lissimore. Osteochondral plugs had a significantly (Mann-Whitney; n=5; P=0.0079) lower mean margin of cell death with the Lissimore osteotome (117.8+/-8.97 microm) than the Acufex MP (315.3+/-5.90 microm).

Cutting-tip profile is an important factor in determining the extent of marginal death in circular osteochondral grafts. We have designed and assessed an alternative cutting-tip, which caused significantly less marginal death than the commercially available Acufex. We conclude that there is scope for improvement of osteochondral harvest techniques.