Accuracy of 2D Digital Templating for Total Hip Arthroplasty in Patients With Crowe Type-4 Dysplastic Hips

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Background There is a paucity of studies reporting the outcomes of preoperative digital templating in Crowe type 4 hips. The aim of this study was to evaluate the accuracy and clinical role of digital templating applied in Crowe type 4 hips. Methods Patient data were obtained from electronic patient records covering the period from January 2016 to December 2019. Data on side, gender, and age, the amount of femoral shortening, and the size of the implants were noted. Upon two dimensional (2D) digital templating, femoral implant size and positioning, length of femoral shortening, and acetabular implant size and positioning were predicted. The agreement for acetabular size, femoral size, and femoral shortening measurements was tested both for the senior arthroplasty surgeon and the senior resident. Results Senior surgeon templating demonstrated moderate agreement with implanted acetabular (κ = 0.410) and femoral (κ = 0.432) component sizes, outperforming the senior resident (acetabular κ = 0.071; femoral κ = 0.265). Exact acetabular and femoral size prediction by the senior surgeon was 74% and 36%, respectively. Femoral shortening agreement was moderate for the surgeon (intraclass correlation coefficient [ICC] = 0.544) and fair for the resident (ICC = 0.400), whereas interobserver agreement for shortening was excellent (ICC = 0.958). Conclusions The accuracy of 2D digital templating for predicting component size in total hip arthroplasty for Crowe type IV dysplastic hips was limited. Nevertheless, when performed by an experienced surgeon, 2D digital templating remains a valuable preoperative planning tool for planning and estimating the required femoral shortening, while final implant selection should be based on intraoperative findings.