The aim of our study was to determine the usefulness of preoperative digital templating of cementless total hip arthroplasty (THA).

60 consecutive cementless THA (synergy stem & reflection cup) were templated digitally by two senior hip arthroplasty fellows (GM, YG) independently. A metallic marker ball of known diameter was used in all images to help scale for magnification. A blinded observer then collated information on the actual implant sizes, size of head component, offset, and level of neck cut intraoperatively. This was used to statistically analyse the correlation (Interclass correlation coefficient) between the digitally templated implant sizes and actual implant sizes used and the reliability of digital templating.

A high rate of coincidence between digitally templated estimates and actual implant sizes was noted for both groups of templates. A high intraclass correlation coefficient (ICC) for the acetabular cup, stem and head were noted (ICC of 0.825, 0.794, and 0.884 respectively). Moderate agreement was noted for neck cut (ICC of 0.567) and leg length (ICC of 0.612).

In conclusion, digital templating can reliably estimate implant sizes in cementless total hip arthroplasty. Valuable information on neck cut and leg length can be obtained by preoperative templating.