OUTCOMES OF THE STRYKER TRIDENT ‘ALL-POLY’ CEMENTED CONSTRAINED ACETABULAR INSERT IN 252 PATIENTS: A DISTRICT GENERAL EXPERIENCE

Constrained acetabular inserts are designed for revision procedures but increasingly being used for complex primaries. Evidence surrounding their use is limited and concerns linger around their survivorship. We have been cementing this insert directly into the acetabulum for over 15 years and accumulated one of the largest series in the literature. Data was obtained retrospectively from trust NJR records between 20/05/2008 and 23/09/2024. Both primary and revision procedures were included. Routine demographic data, comorbidities and mortality were recorded. Patient records and all pre and post-operative radiographs were studied to identify complications. Patients were subdivided into short, intermediate and long-term follow-up of 2-years, 5-years and 10-years respectively. 252 patients were identified comprising 31.7% (80) male and 68.3% (172) female. Mean age was 79.7 years (47–98). 48.4% (122) were primary constrained THR's and 51.6% (130) were revision. The most common reason for constrained insert in primary cases was a perceived high dislocation risk and for revisions it was recurrent dislocations. 30-day mortality was 1.2% (3) and 1-year mortality was 5.6% (14). 70 patients were within 2-year of surgery. There were 3 complications; periprosthetic fracture (revised to uncemented modular stem), constrained cup pull-out (patient decided against surgery) and ring breakage resulting in head dislocation (died before revision). 77 patients had a minimum follow-up of 2-years. There were 2 complications; constrained cup pull-out (patient decided against surgery) and ring breakage resulting in head dislocation (underwent revision to constrained insert). 68 patients had a minimum follow-up of 5-years. There were 4 complications; 2 ring breakages resulting in head dislocation (one revised to constrained, the other underwent a Girdlestone procedure) and 2 PJI's (underwent two-stage revision). 37 patients had a minimum follow-up of 10-years. There were 3 complications; ring breakage without head dislocation (treated non-operatively) and 2 PJI's (underwent two-stage revision). Our results demonstrate a low overall mechanical complication rate of 3.2% when this constrained insert is cemented directly into the acetabulum without a metal shell, providing a viable option in high-risk primary and revision hip arthroplasty procedures.