Abstract
Background: Our multi-centre international randomized controlled trial compared the one-year incidence of dislocation between a 36 mm and 28 mm metal on highly cross-linked polyethylene articulation in primary and revision total hip replacement (THR).
Patients: 644 patients were entered into the study. Surgical approach was posterior in primary THR and posterior, transfemoral or transtrochanteric in revision THR. Patients were stratified according to a number of factors which may influence dislocation risk and polyethylene wear. Patients were randomized intra-operatively to either a 28 or 36 mm articulation.
Results: The 12-month incidence of dislocation was statistically significantly lower in patients undergoing THR with a 36 mm articulation than in those with a 28 mm articulation (1.3% vs 5.4%, p=.004). When primary and revision THR were examined separately, the 12-month incidence of dislocation was statistically significantly lower in patients undergoing primary THR with a 36 mm articulation than in those with a 28 mm articulation (0.8% vs 4.4%, p=.007). Of the 12 primary THR patients with a 28 mm articulation who dislocated within one year, four experienced recurrent dislocation and two were revised for dislocation. Two patients with a 36 mm articulation dislocated, one of whom experienced recurrent dislocation and was revised. The incidence of dislocation after revision THR with a 36 mm articulation was 4.9%, compared to 12.2% with a 28 mm articulation. Three of the five patients who dislocated following revision THR with a 28 mm articulation experienced recurrent dislocation and were revised within one year of surgery. Two patients dislocated following revision THR with a 36 mm articulation but neither experienced recurrent dislocation or further revision.
This large randomized study unequivocally shows for the first time that, compared to a 28 mm articulation, a 36 mm articulation in THR is efficacious in reducing the incidence of dislocation in the first year following THR.
The abstracts were prepared by Mr Matt Costa and Mr Ben Ollivere. Correspondence should be addressed to Mr Costa at Clinical Sciences Research Institute, University of Warwick, Clifford Bridge Road, Coventry CV2 2DX, UK.
