A Standardised Protocol for Pre-operative Pelvic Radiographs for Templating in Total Hip Arthroplasty

Digital templating using pre-operative radiographs enables pre-operative planning for total hip arthroplasty (THA). This allows surgeons to reproduce hip biomechanics effectively, reducing the risk of post-operative complications. Pelvic radiographs demonstrating the head, neck, trochanters, and proximal one-third of the femoral shaft allow calculation of key measurements including femoral offset and limb length discrepancy (LLD). Currently, no standardised guideline exists for obtaining pre-operative radiographs for templating in THA.  Materials and methods: A single-blinded retrospective cohort study assessing the quality of pre- and post-operative radiographs of 195 patients who underwent elective THA for osteoarthritis over a two-year period was performed. Quality was rated as good, fair or poor, respectively, depending upon whether ≥2, 1 or none of the following were met: Pubic symphysis (PS) and coccyx in a straight line with 1-3 cm between the superior edge of the PS and tip of coccyx, trochanters distinguishable, obturator rings symmetric. Post-operative images were assessed to determine whether the distal end of the implanted prosthesis was visible.  Results: The sample consisted of 195 patients. Pre-operatively 115 (59%) radiographs were classified as good, 71 (36.4%) fair and 9 (4.6%) poor. Post-operatively 46 (23.6%) were classified as good, 114 (58.4%) as fair and 30 (15.4%) as poor. In the post-operative radiographs, 25.6% did not include the distal tip of the prosthesis.  Conclusion: This study highlights significant scope to improve the quality of pre-operative radiographs, allowing accurate templating to optimise outcomes for THA. A protocol is recommended whereby the pelvic radiograph is centred on the PS at the lesser trochanter level, ensuring adequate exposure of the proximal femur, acetabulum and iliac crests.