Abstract
Introduction
Inappropriate soft tissue tension around an artificial hip is regarded as one cause of dislocation or abductor muscle weakness. It has been considered that restoration of leg offset is important to optimise soft tissue tension in THA, while it is unclear what factors determine soft tissue tension around artificial hip joints. The purpose of the present study was to assess how postoperative leg offset influence the soft tissue tension around artificial hip joints.
Materials and Methods
The subjects were 89 consecutive patients who underwent mini-incision THA using a navigation system through antero-lateral or postero-lateral approach. Soft tissue tension was measured by applying traction amounting to 40% of body weight with the joint positioned at 0°, 15°, 30°, and 45° of flexion. The distance of separation between the head and the cup was measured using the navigation system.
Results
The distance of cup/head separation differed significantly for different angles of flexion, with the greatest distance at 15° of flexion which was 11±5 (SD) mm. Stepwise multiple regression analysis showed that postoperative leg offset discrepancy, antero-lateral approach, preoperative abduction ROM were correlated with the distance of cup/head separation at 15° of flexion. Postoperative leg offset discrepancy were also correlated negatively with the distance of cup/head separation at 0° and 30° of flexion.
Conclusion
Postoperative leg offset discrepancy influenced significantly the soft tissue tension around THA at a wider range of flexion.
