Comparison study of temperature and deformation changes in the femoral component of a novel ceramic-on-ceramic hip resurfacing bearing to a metal standard, using a cadaveric model.

Hip resurfacing is an attractive alternative to total hip replacement preserving bone and reducing dislocation risk. Recent metal-on-metal designs have caused failure due to metal wear debris. Ceramic implants may mitigate this risk. Temperature increase in periprosthetic bone during cementation can lead to osteonecrosis, while deformation of the component can affect joint lubrication and may increase wear through clamping. Both processes may lead to implant loosening. This study quantifies the temperature and deformation change in a novel ceramic hip resurfacing femoral component compared to a metal standard during cemented implantation in a fresh frozen cadaveric model. Study design and methods Eight femora were prepared from four fresh frozen cadavers. One surgeon experienced in hip resurfacing surgery (J.H.) prepared the femora by reaming. Four ceramic and four metal implants of equal and varying size were cemented in place. Bone and surface temperatures were taken using a probe in the periprosthetic bone and an infrared laser thermometer, respectively. Deformation was measured using a micrometre. Measurements were taken before implantation and every 5-min intervals up to 30 min. The average bone-temperature increment was lower for ceramic heads than for metal heads. Although this difference was not statistically significant, the average bone temperature incremental change in small sizes (42 and 46 mm) was higher than in the large sizes (48 and 50 mm). Most metal heads sustained bearing diameter change that was still near its peak value 30 min after implantation, whereas the ceramic heads suffered a lower diameter change and most of the samples recovered their original diameter 30 min after implantation. Both implants behave similarly, however, a lower temperature rise in bone was observed with ceramic heads. This may lower the risk for thermal damage on periprosthetic bone. The ceramic heads deformed less during surgical implantation. This was not significant.