Abstract

Digital templating of pre-operative radiographs is increasingly utilised by surgeons before total hip arthroplasty (THA) as part of an adequate pre-operative preparation to minimise complications. Templating can accurately predict the required implant sizes but its use in facilitating correction of leg length discrepancy (LLD) has been under-reported in the literature. We performed a retrospective analysis of a cohort of consecutive patients undergoing primary THA. A comparison was made of the implant sizes templated with actual sizes used. In addition, pre-operative leg-length discrepancy (LLD) was noted and compared with intra-operative measurement of LLD correction and post-operative LLD correction seen on post-operative radiographs, as measured by two independent observers. Statistical analysis was performed to investigate the correlation between pre- and post-operative measurements. Fifty nine patients that had primary THA were investigated, 42 with hybrid replacements, 17 with cemented replacements. Spearman's-rho 2-tailed correlation between templated and implanted femoral offset, stem size and acetabular cup size was 0.850, 0.709 and 0.834 respectively (p < 0.01 for all). Correlation between the pre-operative templated LLD and the measured post-operative corrected LLD was 0.841 (p < 0.01). No difference existed between hybrid and cemented hips or the presence or absence of a contralateral hip replacement. In this study, templating for THA was significantly accurate in predicting the required femoral and acetabular implant sizes. In addition, the correction of pre-operative LLD was accurately performed, as evidenced by measurement on post-operative films. The results of this study support the pre-operative digital templating of radiographs in total hip arthroplasty.