A novel positioner for accurately sitting the acetabular component: a retrospective comparative study

Introduction

In this study, we described a positioner which allows a combination of preoperative plan and intraoperative insertion of the cup to improve the reconstruction of the rotation center of the hip.

Materials and methods

A retrospective study was conducted on 32 consecutive patients (group A) using this positioner and 40 consecutive patients (group B) using conventional method; radiological parameters and clinical measurements before operation and at last follow-up were collected and evaluated.

Results

Group A had a reconstructed center of rotation (COR) that was 0.19 mm closer to the anatomic COR in height (P < 0.005), compared with group B with 3.45 mm vertical dislocation. There were no statistically significant differences in the horizontal displacement between the two groups. The accuracy of cup inclination was 42.14 ± 3.57 in the group A and 38.73 ± 7.65 in the group B (P = 0.015). The accuracy of cup anteversion was 14.82 ± 1.44 in the group A and 13.08 ± 5.95 in the group B (P = 0.082). All cups in the group A were radiologically stable, while one cup in the group B was radiologically unstable and was successfully treated with second-stage revision. Both of the groups obtained a higher mean postoperative Harris Hip Score.

Conclusions

Utilizing this positioner helps to restore the COR position more precisely and provides satisfactory radiological and clinical outcomes in the short term, and more studies are required before its widespread adoption for complicated cases.