Does Using Constrained Acetabular Component Really Limit Hip Range of Motion?

Aim: In surgical treatment of instability, constrained acetabular inserts are frequently used in hip arthroplasty. However the reasons why surgeons avoid constrained acetabular components are the concern of an increased rate of loosening possibly due to impingement and the concern of decreased range of motion. This study aims to investigate the influence of constrained acetabular insert usage on hip range of motions and functional results. Material and Methods: Twenty-eight patients who needed revision hip arthroplasty were included. Patients were divided into two groups according to acetabular insert used in surgery (constrained and non-constrained). Mean follow-up period was 61±7 months (range, 50-74) in constrained group and 59±7 (range, 50-72) in non-constrained group. Hip range of motion and harris hip scores were recorded pre-operatively and at final follow-up. Results: The final avarage flexion, abduction, adduction, external rotation and internal rotation was respectively 78°±15°, 43°±4°, 28°±3°, 30°±7°,19°±8° in constrained group (n=15) and 75°±14°, 40°±6°, 26°±5°, 30°±12°, 17°±6° in non-constrained group (n=13). The difference between groups was not statistically significant. Harris hip score increased in both groups and there was no significant difference between groups (p=0.730). Conclusion: Findings of this mid term study showed that hip range of motions and functional results in patients with constrained acetabular inserts are not inferior than the patients with non-constrained inserts.