Constrained acetabular inserts provide a solution for both complex primary and revision hip arthroplasty, but there have been ongoing concerns for high risk of failure and their longevity. The Stryker® Trident acetabular insert is pre-assembled with its constrained ring. We believe this to be the largest series of constrained acetabular inserts with a minimum of 5 year follow-up.

We retrospectively reviewed all Stryker® Trident ‘All-Poly’ constrained acetabular inserts cemented into bone in our unit between 2008 and 2016. We collated demographic details and reviewed all patients’ radiographs and clinical notes. Indications for surgery, latest Oxford Hip Scores (OHS) and clinical and radiographic complications were identified.

117 consecutive Stryker® Trident ‘All-Poly’ constrained inserts were cemented into bone in 115 patients during the study period with a mean age of 80 (47–97). Most common indications for surgery were recurrent dislocation (47), complex primary arthroplasty (23), revision arthroplasty (19) and failed hemiarthroplasty (12). 41 patients required revision of the acetabular component only. Follow-up was a minimum of 5 years (mean 8.6, range 5–13). There were three 30-day mortalities and six 1-year mortalities. The mean latest OHS was 37 (24–45). Four cups failed in three patients, one at the cement-bone interface, two at the cement-prosthesis interface and one at the bipolar interface. These were treated conservatively in three patient and with excision arthroplasty in one patient. There were four peri-prosthetic fractures, one Vancouver C distal femur fracture treated conservatively and three Vancouver B1 fractures, two treated conservatively and one treated with open reduction internal fixation. There was breakage of one constrained ring with no adverse effects and one superficial wound infection requiring oral antibiotics only.

This series demonstrated that despite the elderly and complex nature of these patients’ clinical situations, constrained acetabular inserts offer a useful and pragmatic solution, with relatively low complications, including in our series a cup failure rate of 3% and peri-prosthetic fracture rate of 3%.

Outcomes for patients with acute illnesses may be affected by the day of the week they present to hospital. Policy makers state this ‘weekend effect’ to be the main reason for pursuing a change in consultant weekend working patterns. However, it is uncertain whether such a phenomenon exists for elective orthopaedic surgery.

This study investigated whether a ‘weekend effect’ contributed to adverse outcomes in patients undergoing elective hip and knee replacements.

Retrospectively collected data was obtained from our institutions electronic patient records. Using univariate analysis, we examined potential risk factors including; Age, Sex, ASA Grade, Comorbidities, as well as the day of the week, hospital admission and surgery occurred. Subsequent multivariate analyses identified covariate- adjusted risk factors, associated with prolonged hospital stays. 30-day mortality data was assessed according to the day of the week surgery was performed.

892 patients underwent arthroplasty surgery from 01/09/2014 till the 31/08/2015. 457 patients had a total hip and 435 had a total knee replacement. 814 patients (91.3%) underwent surgery during the week, while 78 (8.7%) had surgery on a Saturday. There was no difference in the average Length of Stay (LOS) between groups (5.0, 2.6 versus 5.0, 3.4, p=0.95), and weekend surgery was not associated with a LOS greater than 4 days. The two variables found to be associated with a prolonged LOS were; increasing age (RR) 1.02 (95% CI: 1.01–1.03, p<0.001) and an ASA score of 2, (RR) 1.6 (95% CI: 1.15 − 2.20, p=0.005). There was one death in a patient who was ASA III, and who underwent surgery on a Monday.

There is no ‘weekend effect’ for elective orthopaedic surgery. Changes in consultant weekend working patterns are unlikely to have any effect on mortality or LOS for elective orthopaedic patients.