Preoperative Templating in PACS for Total Hip Replacement

Kim, Myoung Soo; Jeong, Moo Chul; Ji, Nam Gu; Lee, Jung Sub; Kim, Jeung Il; Suh, Kuen Tak

Abstract

PURPOSE
The objective of our study was to compare preoperative "Monitor Templating" with postoperative results for total hip replacement and to investigate the accuracy of "Monitor Templating" that was carried out by monitoring with picture archiving communication system (PACS).
MATERIALS AND METHODS
Forty five patients underwent primary cementless total hip replacements. For setting parameters, we located the 10cm rod placed in the medial thigh on anteroposterior view of both hips and in the anterior thigh on Lowenstein lateral view. We measured implant sizes and the predictive value of corrective change in leg length and horizontal offset, by using radiographs magnified 120% of the anteroposterior views of both hips and Lowenstein lateral view of PACS on 27 inch monitor. We examined the correlation between preoperative monitor templating and the actual implant size, postoperative leg length and horizontal offset difference.
RESULTS
The preoperative monitor templating showed a high rate of coincidence with the actual implant size, the postoperative leg length, and the horizontal offset difference. The averages in accurate prediction were 98% in the acetabular cup, 98% in the femoral stem, 97% in the postoperative actual difference of leg length, and 97% in the horizontal offset. With regard to leg length discrepancy, the sick limb was on average 4.7 mm shorter and 0.5 mm longer postoperatively than the contralateral limb. The average ratio of horizontal offset of the sick limb to the contralateral limb was 94.6% preoperatively and increased to 97.8% postoperatively.
CONCLUSION
Preoperative "Monitor Templating" using PACS images on 26 inch monitor is an easy and effective method for predicting implant size, correcting leg length discrepancy and restoring horizontal offset.