Interobserver Reliability of Acetate Templating on Calibrated Digital X-Rays for Total Knee Replacement

Objectives This study aimed to investigate the interobserver reliability of a hybrid templating method for total knee arthroplasty, utilizing conventional acetate templates in conjunction with calibrated digital radiographs displayed on a computer screen. Methods Two orthopedic surgeons independently performed templating to estimate implant sizes for 30 knees in 26 patients. Standardized digital anteroposterior (AP) and lateral knee radiographs were obtained for each patient, with a custom copper rod positioned at the level of the knee joint to facilitate calibration. Digital radiographs were calibrated for magnification using a ruler on the computer screen. Templating was then conducted by overlaying acetate templates onto the digital images. Results For the first observer, 60% (36/60) of the estimations matched the actual implant sizes used. This increased to 98.3% (59/60) when considering estimations within one size of the actual components. For the second observer, 61.7% (37/60) of the estimations were exact matches, and 100% (60/60) were within one size of the actual components. The interclass correlation coefficient (ICC) was 0.92 (95% confidence interval [CI]: 0.87–0.95). Conclusion The hybrid templating method for total knee arthroplasty, employing conventional acetate templates over digital radiographs, demonstrates high interobserver reliability and may provide a cost-effective alternative for orthopedic surgeons lacking access to dedicated digital templating software.