抄録
Objective: We developed a new assistant device which is useful during bipolar hip arthroplasty (BHA) using the direct anterior approach (DAA). Trial reduction during DAA-BHA is difficult; however, the device, which we named “half cup”, makes it easy.
Methods: A single surgeon performed 15 DAA-BHAs between July 2008 and November 2009 in patients with femoral neck fractures. We divided the patients into two groups: those operated on using the half cup (HCU) or those operated on not using the half cup (HCN). In the HCN group (6 hips), conventional trial reduction was not performed; however, in all cases reduction of the inner head to acetabulum was performed as a substitute. In the HCU group (9 hips), trial reduction with the half cup was performed in each case. We evaluated the operating time, complications (e.g., fractures), and leg length discrepancy on X-ray in the two groups.
Results: The mean operating time was 78.2 (6684) min in the HCN group and 69.8 (6083) min in the HCU group. No complications were seen in either group. The mean leg length discrepancy was +0.5 (-3 to +5) mm in the HCN group and -0.7 (-2 to 0) mm in the HCU group. It seemed that the range of leg length discrepancies in the HCU group was smaller than that of the HCN group, and there was no positive value of discrepancy in the HCU group. Trial reduction was easily done in the HCU group.
Conclusion: In DAA-BHA, there were no significant differences in operating times or complications between the groups. However, the range of leg length discrepancies in the HCU group was less than that of HCN group. The half cup assistance device clearly made trial reduction easy and was useful for choosing appropriate implants.
