A feasibility study of the use of an MRI based patient specific knee arthroplasty system within the NHS.

Introducing new technologies within a public funded health system can be challenging. We assess the use and potential benefit of customised jigs for knee arthroplasty. Outcomes assessed were safety and accuracy of implantation.

Eight knee replacements using custom jigs were compared to 11 conventionally instrumented replacements matched to surgeon and operative day. Parameters measured include tourniquet time; drain output; hospital stay; adjusted change in haemoglobin; complications; and component position on post-operative long-leg alignment films

None of the parameters observed demonstrated a statistically significant difference from the conventional arthroplasty group. No complications were seen in either group. No significant differences were seen in alignment.

Our early experiences show that this technology appears safe and allows accurate implantation of the prosthesis. There was a trend for decreased stay and blood loss. The health economic benefits of navigational arthroplasty have been demonstrated in other studies and come from the lack of instrumentation of the intramedullary canal. MRI based patient specific instrumentation is considered technically easier and more convenient than intra-operative navigation. A larger study is planned to assess the health economic implications of adopting this new technology.