Causes for revision of dual-mobility and standard primary total hip arthroplasty : Matched case-control study based on a prospective multicenter study of two thousand and forty four implants.

INTRODUCTION

The causes for revision of primary total hip arthroplasty (THA) are various and quite well known. The developing use of dual-mobility THA (DM-THA) seems a relevant option to decrease the risk of instability. Due to lack of long-term follow-up, this innovative retentive concept is suspected to increase the risk of polyethylene (PE) wear. the aim of the study was to analyse the causes for DM-THA revision and assess whether or not its occurrence is different from that of fixed-standard (FS) THA , particularly for aseptic loosening or wear and/or osteolysis.

MATERIALS AND

METHODS

The SoFCOT group conducted an observational prospective multicentre study from 1 January 2010 to 31 December 2011. Inclusion criteria comprised an exhaustive collection of 2044 first-revision THAs with 251 DM-THAs and 1793 FS-THAs. After excluding complications linked to patient factors (infection and periprosthetic fractures), we performed a matched case-control study (matching ratio 1:1) comparing two groups of 133 THAs.

RESULTS

Revisions for aseptic loosening or osteolysis/wear were as frequent in DM-THA (58.7 %) as in FS-THA (57.1 %) (p 0.32); 7.5 % of DM-THA were revised for dislocation versus 19.5 % of FS-THA (p 0.007).

DISCUSSION: Revision for osteolysis/wear and aseptic loosening were as frequent in DM-THA as in FS-THA; revision for dislocation was less frequent in DM-THA. This confirms the efficiency of the DM concept regarding the risk of dislocation. Causes for revision were different between groups, and revisions for dislocation were less frequent in DM-THA. Only prospective comparative studies could provide reliable information that may support broader use of the DM concept.