The effect of femoral head size on functional outcome in primary total hip arthroplasty: a single-blinded randomised controlled trial.

We conducted a prospective single-blinded randomised controlled trial to compare the functional and quality of life outcomes in two groups of patients between 60 and 80 years of age undergoing THR; the first receiving a small head (28-32 mm) metal on polyethylene (MoP) articulation, and the second receiving a large head (44-54 mm) metal on metal (MoM) articulation. We recruited 49 patients and randomised them into one of the two groups (22 MoP and 27 MoM). The results demonstrated no statistical difference in any of the assessed functional outcomes at any follow-up point (p>0.05). There were no dislocations or revisions in either group. Although it has been suggested that large head MoM articulations in THA offer superior stability and function, our results suggest that small head MoP articulations can achieve comparable ROM, function and quality of life at short-term follow-up.