Comparative Analysis of Preoperative Templating in Total Hip Replacement Surgery: KingMark™ Dual-Marker System Versus Single-Marker Method

Purpose of the study Total hip replacements (THRs) are a standard and effective surgical procedure that benefits from preoperative planning. Despite this, no consensus exists on the best preoperative templating tool for THRs. In this study, we compare the single marker to the KingMark™ double-templating system for predicting the size of implants used intraoperatively. Methods This retrospective study compares two cohorts of 50 consecutively selected patients who underwent primary THR under the care of two orthopaedic surgeons. All patients had preoperative anteroposterior (AP) pelvic radiographs to facilitate templating by one of the two methods. The first cohort had surgery with single-marker templated THRs from August to December 2021. The second cohort had THRs templated using the KingMark™ system and underwent surgery between January and April 2022. For both groups, the templated size of the acetabular and femoral implants was compared to the definitive acetabular and femoral implants, respectively. Any patients with a history of previous hip surgery, with developmental abnormality affecting hip anatomy, or requiring bespoke implants were excluded. Results Single-marker templating accurately predicted the femoral implant size in 32% of cases. KingMark™ correctly predicted femoral implant size in 54% of cases, a statistically significant improvement (p=0.04). The mean templated acetabular cup size for the single-marker cohort templated acetabular size was 52.5±4.1, and the definitive acetabular size was 53.6±3.5. The mean templated acetabular cup size for the KingMark™ cohort was 52.0±3.7, and the definitive acetabular cup size was 53.2±4.8. The absolute difference between templated and definitive acetabular implants was 2.3±2.4 and 2.2±2.6, respectively, which was not statistically significant (p=0.84). This is consistent with the rate of accurate acetabular implant prediction for both templating methods (32% for single marker and 30% for KingMark™) with no significant difference (p=0.83). Conclusion The KingMark™ system showed superior accuracy in predicting the femoral stem size in THR over the conventional single mark. However, it's important to note that there was no significant difference between the two methods in predicting the cup size, a key finding of our study.