Surgical approach does not influence instability risk in primary total hip arthroplasty with monobloc dual mobility cup.

Abstract

The impact of the surgical approach on the risk of dislocation in total hip arthroplasty (THA) remains controversial, particularly when monobloc dual mobility cups (DMCs) are used. This study aimed to compare dislocation and complication rates between the postero-lateral and direct anterior approaches with a DMC in primary elective THA, based on data collected from a single center. Between 2010 and 2022, 1,378 consecutive primary THAs were performed using a monobloc DMC. There were 824 performed by direct anterior approach (DAA) and 554 by postero-lateral approach (PLA). Exclusion criteria were cemented implants, patients treated for femoral neck fracture, developmental hip dysplasia, osteosynthetic complications, and follow-up of less than one year. Complications and revisions were analyzed retrospectively. The mean follow-up was 39 months (range, 12 to 157). There was no statistically significant difference between the risk of dislocation with the anterior approach (n = 0; 0%) compared with the posterior approach (n = 2; 0.4%) (P = 0.16). There were more major complications, such as femoral fractures, in the PLA group in an older, more overweight, and higher ASA (American Society of Anesthesia) score population. In total hip arthroplasty using monobloc dual-mobility cups, the dislocation rate with the postero-lateral approach is no higher than with the direct anterior approach. The low incidence of dislocations in this large cohort supports the benefits of using monobloc DMCs.