Clin Orthop Surg.  2024 Feb;16(1):16-22. 10.4055/cios21219.

Optimization of Acetabular Cup Abduction by Adjusting Pelvic Pitch

• Park JW
• Park JH
• Kim HS
• Lee YK
• Han KY
• Ha YC
• Koo KH

• KMID: 2550824
• DOI: http://doi.org/10.4055/cios21219

Abstract

Background
The purposes of this study were to determine the accuracy of our cup positioning method and to evaluate the dislocation rate after total hip arthroplasty (THA).
Methods
After positioning the patient in the lateral decubitus position on the operation table, an anteroposterior view of the hip was taken. The pelvic pitch was measured on the X-ray. A positive pitch was defined as the caudal rotation of the upper hemipelvis. Our target abduction of the cup was 43°. We used the cup holder to guesstimate the cup abduction. In a preliminary study, we found that the weight of the cup holder increased the pelvic pitch by 5°. Thus, the target abduction of the cup holder was calculated by a formula: 43° – pelvic pitch – 5°. During the cup insertion, the cup holder was anteverted to the calculated target according to the concept of combined anteversion. We evaluated 478 THAs (429 patients), which were done with the use of the method.
Results
The mean cup abduction was 43.9° (range, 32.0°–53.0°) and the mean error of cup abduction was 2.4° (standard deviation [SD], 2.0°; range, 0.0°–11.0°). The mean cup anteversion was 28.5° (range, 10.0°–42.0°) and the mean error of cup anteversion was 6.7° (SD, 5.2°; range, 0.0°–27.6°). Of all, 82.4% of the cups (394 / 478) were within the safe zone: 30°–50° abduction and 10°–35° anteversion. During 2- to 5-year follow-up, no hip dislocated.
Conclusions
Our adjusting method according to the pelvic pitch can be a reliable option for optimizing the cup abduction in THA.

Keyword

Total hip arthroplasty; Cup position; Treatment; Pelvic pitch