Determining the Accuracy of Acetabular Cup Size using Acetate Templates on Digital Radiographs in Patients Undergoing Total Hip Replacement

Introduction: Accurate pre-operative templating is essential for successful total hip replacement (THR) to optimize component sizing and minimize complications. With the transition to digital radiography, traditional acetate templating faces compatibility challenges. This study evaluates the accuracy of acetate templates on magnified digital radiographs as a cost-effective alternative to digital templating software. Materials and Methods: A prospective observational study was conducted over 18 months on 25 patients undergoing uncemented total hip arthroplasty (THA) at a tertiary care center. Standardized anteroposterior pelvic radiographs with a 3 cm metal marker were obtained. Digital images were magnified to match the acetate template scale. Pre-operative predictions were compared with actual intraoperative acetabular cup sizes. Results: The mean patient age was 66.60 ± 5.74 years with male predominance (68%). Osteoarthritis was the most common indication (48%). Pre-operative templating predicted acetabular cup size with 88% exact match and 100% accuracy within ±2 mm. Most radiographs were rated good quality (64%). The most common cup sizes used were 50 mm and 54 mm. Conclusion: Acetate templating on digital radiographs provides highly accurate, reliable, and cost-effective prediction of acetabular cup size in THA. This method demonstrates excellent predictive power with 88% exact match and 100% accuracy within ±2 mm, making it a valuable tool, especially in resource-limited settings where advanced templating software may be unavailable.