Conventional versus digital preoperative templating in primary total hip arthroplasty at Hospital Sultanah Bahiyah

Introduction and objectives: Templating is part of preoperative planning for total hip arthroplasty surgery. Conventionally this was done using on acetate transparent films overlaid on hard copy radiographs. With the emergence and implementation of digital radiograph, digital templating software was introduced in total hip arthroplasty. We conducted the study to compare the accuracy of conventional templating techniques and digital templating techniques in primary total hip arthroplasty. Methodology: This was a retrospective study done on 73 cases where primary total hip arthroplasty was performed for osteoarthritis, avascular necrosis of femoral head and femoral neck fracture in Hospital Sultanah Bahiyah Alor Setar, Kedah, Malaysia from June 2011- June 2014. In a separate sitting, conventional templating was performed using hard copy radiographic films with implant specific templates whereas digital templating was performed using a magnification- calibrated digital radiographic images and TraumaCadTM templating software on a computer workstation. Paired t tests were used to determine the accuracy of conventional templating versus digital templating. We also used Bland-Altman Method and to determine the agreement between conventional method and actual implant as well as digital method and actual implant. Results: Both the conventional and digital template had quite a good agreement with the actual implant in predicting the acetabular cup and femoral stem size. However, digital templating had higher agreement to the actual implant size as compared to conventional templating in predicting the acetabular cup and femoral stem size. Conventional templating significantly under predicted cup size (P-value = 0.003) and the digital templating slightly over predicted the cup size but was not statistically significant (P-value =0.501). Conventional templating significantly over predicted femoral stem size ( P-value = 0.004) while digital templating slightly over predicted the femoral stem size but was not statistically significant (P-value =0.103). Therefore digital templating is more accurate than conventional templating in the preoperative assessment. Conclusion: Digital templating is more accurate in predicting the acetabular cup and femoral stem size than conventional templating using the available software. Key words: Templating , conventional, digital, total hip arthroplast