The cumulative incidence of dislocation and revision surgery following total hip arthroplasty for hip fracture in New South Wales : a data linkage study.

AIMS: Dislocation is a common problem after total hip arthroplasty (THA) for hip fracture. This study aimed to assess the one-year cumulative incidence of dislocation, and identify associated risk factors.

METHODS

An observational cohort study was conducted using data from the Australian Orthopaedic Association National Joint Replacement Registry linked with the New South Wales Admitted Patient Data Collection. Patients aged over 18 years who underwent THA for fracture neck of femur between 1 July 2010 and 31 December 2018 in New South Wales were included. Dislocations and revision surgeries were identified via linked datasets. Multivariable logistic regression evaluated demographic, surgical, and implant-related risk factors for dislocation. Subgroup analysis considered surgical approach and BMI.

RESULTS

Among 4,632 patients, the one-year dislocation incidence was 4.8% (95% CI 4.2 to 5.5), with 79% occurring within 90 days. Revision for dislocation occurred in 1.1% of cases (95% CI 0.80 to 1.4). Compared with dual-mobility acetabular components, conventional bearings ≤ 32 mm (odds ratio (OR) 1.64 (95% CI 0.93 to 2.90); p = 0.087) and > 32 mm (OR 1.33 (95% CI 0.75 to 2.37); p = 0.332) showed no significant difference in dislocation risk. In a subgroup of 2,532 patients, the anterior approach significantly reduced dislocation risk (OR 0.28 (95% CI 0.12 to 0.67); p = 0.004), whereas the lateral approach did not (OR 0.75 (95% CI 0.48 to 1.17); p = 0.202) compared to the posterior approach. Adjusting for surgical approach, ≤ 32 mm bearings were associated with a higher dislocation risk than dual-mobility components (OR 1.97 (95% CI 1.06 to 3.66); p = 0.031); > 32 mm bearings were not significantly different (OR 1.68 (95% CI 0.89 to 3.15); p = 0.110).

CONCLUSION

One in 20 patients undergoing THA for fracture will experience dislocation within a year, though most will not require revision. Dual-mobility components may be protective against dislocation compared with smaller-diameter femoral head sizes.