Digital templating for THA planning; efficiency and accuracy improves with institutional familiarity

Pre-operative templating has become an important routine for many surgeons in planning for total hip arthroplasty surgery. Accurate THA templating reduces surgical time, increases precision, reduces the need for revision and reduces the overall complication rate. Incorrect placement of the scaling ball will lead to a magnification error with a subsequent templating error.

Digital radiographs of 211 patients undergoing primary THA by a single surgeon were reviewed. Two separate sets of consecutive digitally templated radiographs where reviewed and compared with regards to: accuracy of scaling ball placement and accuracy of templating. The interval was chosen to allow bedding in of, and familiarity with the templating system between orthopaedics, nursing and radiographers, and to ascertain if consistency improved with time in our institution. The positioning of the scaling ball was as assessed and classified as either ideal or non-ideal.

The data collected showed significant improvement (p < 0.0001) in the accuracy of SB positioning over time (70 % 2nd series vs 30.7. Ideal placement produced more accurate digital templating. With acetabular templating a 44.2 % (n = 34/77) versus 27.3 % (n = 9/33) accuracy with exact measurement (p = 0.008) and 83.1 % (n = 64/77) versus 63.6 % (n = 21/33) within ±2 sizes (p = 0.046). The study also demonstrated significant improvement in accuracy of SB positioning when the fat apron is absent (p = 0.042).

In addition to overall efficiencies in planning and preparation, accurate scaling ball positioning, with regards to coronal plane placement, improves the accuracy of both the acetabular and femoral components in digital templating. Ongoing education for all teams (orthopaedic, nursing and radiographers) is essential to optimise hospital templating.