Journal of Orthopaedic Surgery 2014;22(2):173-6
Accuracy of preoperative templating in total hip arthroplasty Andrew Riddick,1 Adam Smith,2 D Phill Thomas3
Southmead Hospital, Bristol, United Kingdom Royal Glamorgan Hospital, Llantrisant, United Kingdom 3 University Hospital of Wales, Cardiff, United Kingdom 1 2
ABSTRACT Purpose. To assess the accuracy of templating in total hip arthroplasty (THA). Methods. Anteroposterior pelvic radiographs of 20 men and 33 women aged 17 to 80 (mean, 60) years who underwent uncemented THA of the right (n=24) and left (n=29) sides using a single prosthesis were reviewed. A 30-mm–diameter scaling ball was placed between the patient’s legs for calculating the magnification factor (MF) of the radiographs. The planned THA was templated using computer software. The positioning of the scaling ball was measured. The preoperative MF was calculated as the size of the ball on radiograph divided by the true size of the ball times 100. The true MF was calculated as the size of the cup on radiograph divided by the true size of the cup times 100. The accuracy of the preoperative MF was calculated as the preoperative MF divided by the true MF times 100. Results. The cup size and stem size were predicted correctly (within one size error) in 87% and 92% of the patients, respectively; no template size was
greater than 3 size errors. The overall mean preand post-operative MFs differed significantly (122% vs. 127%, p
Accuracy of preoperative templating in total hip arthroplasty Andrew Riddick,1 Adam Smith,2 D Phill Thomas3
Southmead Hospital, Bristol, United Kingdom Royal Glamorgan Hospital, Llantrisant, United Kingdom 3 University Hospital of Wales, Cardiff, United Kingdom 1 2
ABSTRACT Purpose. To assess the accuracy of templating in total hip arthroplasty (THA). Methods. Anteroposterior pelvic radiographs of 20 men and 33 women aged 17 to 80 (mean, 60) years who underwent uncemented THA of the right (n=24) and left (n=29) sides using a single prosthesis were reviewed. A 30-mm–diameter scaling ball was placed between the patient’s legs for calculating the magnification factor (MF) of the radiographs. The planned THA was templated using computer software. The positioning of the scaling ball was measured. The preoperative MF was calculated as the size of the ball on radiograph divided by the true size of the ball times 100. The true MF was calculated as the size of the cup on radiograph divided by the true size of the cup times 100. The accuracy of the preoperative MF was calculated as the preoperative MF divided by the true MF times 100. Results. The cup size and stem size were predicted correctly (within one size error) in 87% and 92% of the patients, respectively; no template size was
greater than 3 size errors. The overall mean preand post-operative MFs differed significantly (122% vs. 127%, p
