Tibial fractures are a potential risk after unicompartmental knee replacement (UKR). The aim of this study was to (1) characterise the typical depth and positioning of saw cuts made by surgeons performing mobile UKR, and (2) to assess which bone cuts have the greatest influence on the risk of tibial fracture. In twenty four tibial sawbones used during a training course for UKR surgery the depth of the vertical and horizontal cuts and the depth and angle of the pin hole were measured. All the vertical bone cuts measured were most excessive posteirorly; cuts were 4.25±3.9mm (max:12mm) excessively deep posteriorly and 0.46±1.0mm (max:4mm) excessive anteriorly. The horizontal bone cuts posterior/anterior were not statistically different, and were excessive by 1.26±2.1mm (max:7.5mm) and 0.73±0.9mm (max:3mm), respectively. The tibial resection depth was 8.79±1.7mm on average. Of the 24 sawbones analysed, in 14 the pin hole penetrated the keel and one went through the posterior cortex. Based upon the sawbone measurements, three finite element simulations were performed; an implanted component with (1) no excessive bone cuts, (2) a vertical cut excessive 1mm anteriorly and 10mm posteriorly, (3) a horizontal cut 5 mm excessive both anteriorly and posteriorly. These preliminary experiments found the greatest bone strain in simulation (2). Therefore, to minimise the risk of tibial fracture care must be taken to ensure the vertical cut is not too deep posteriorly. One possible technique to prevent a deep vertical cut would be to saw down onto a shim inserted into a previously performed horizontal cut.
|Published - Apr 2014
|British Association for Surgery of the Knee: Annual Spring Meeting - John Innes Conference Centre , Norwich, UK United Kingdom
Duration: 8 Apr 2014 → 9 Apr 2014
|British Association for Surgery of the Knee
|UK United Kingdom
|8/04/14 → 9/04/14