No clinical difference between large metal-on-metal total hip arthroplasty and 28-mm-head total hip arthroplasty?

PURPOSE: We aimed to test the claim of greater range of motion (ROM) with large femoral head metal-on-metal total hip arthroplasty.

METHODS

We compared 28-mm metal-on-polyethylene (MP) total hip arthroplasty with large femoral head metal-on-metal (MM) total hip arthroplasty in a randomised clinical trial. ROM one year postoperatively was determined in 50 patients. Mean head sizes were 28 mm (MP) and 48 mm (MM).

RESULTS

After one year, the large head MM group showed greater improvement in internal rotation (14 degrees) than the 28 mm group (seven degrees).There were no significant differences in the absolute values of postoperative internal rotation, external rotation, flexion, extension, abduction and abduction.

CONCLUSIONS

Absolute postoperative range of motion did not differ between the two groups. The improvement in internal rotation was greater after large femoral head metal-on-metal total hip arthroplasty. It is however questionable whether this difference is clinically relevant.