Clinical and radiological factors related to dislocation in patients undergoing hip hemiarthroplasty for femoral neck fractures: A case-control study✰.

INTRODUCTION

Dislocation rates are low in patients undergoing hemiarthoplasty (HA) for displaced femoral neck fractures (FNF); however, complications can be devastating. We hypothesize that patients sustaining HA dislocation have different comorbidities and surgical characteristics to those without.

MATERIALS AND

METHODS

In this retrospective matched-control study, we identified 28 patients who sustained dislocation after HA. They were matched 1:2 based of sex and age to a cohort of patients undergoing HA without dislocation. We compared the pre-operative demographic and clinical data, surgical details, mortality and need for further revision or complications. The radiological analysis was performed by measuring the centre edge angle (CEA), acetabular index (AI), the femoral offset (FO), and the residual femoral neck (RFN) after surgery. The minimum follow-up for unrevised patients was one year (range, 1 to 4).

RESULTS

19 (67 %) out of 28 patients in the study group needed further surgery. The 1-year mortality rate was 44 % in the study group and 14 % in the control group (p < 0.001). A longer surgical delay (p < 0.001), dementia and neuromuscular disorders, a greater CEA (mean cases = 46º and controls = 38º; p < 0.001) and a shorter RFN (mean cases = 23.5 mm and controls = 28.4 mm; p = 0.04) was found in patients that suffered HA dislocation.

CONCLUSIONS

HA dislocation after FNF is a severe complication with high mortality rate and often require further surgery treatment. Dislocation was more frequent in patients with neuro-cognitive impairment, a longer surgical delay and a shorter femoral neck. Monitoring peri‑operative management and surgical technique may decrease the dislocation rate in this frail population.

LEVEL OF EVIDENCE: III.