Thirty-two Millimetre Heads and Accelerated Polyethylene Wear in Total Hip Arthroplasty

In total hip arthroplasty 32 mm heads are often used as the greater diameter is thought to contribute to improved stability. However, greater head diameter can also lead to greater volumetric wear.

We compared polyethylene wear between patients with 32 mm heads and those with smaller heads. All patients who had Harris Galante1 metal-backed, uncemented cups inserted between 1986 and 1996 at our institute were annually reviewed clinically and radiographically.

Accelerated polyethylene wear was noted between the fifth and seventh postoperative year in 17 out of 165 total hip replacements with 32 mm heads, but only in 21 out of 961 total hip arthroplasties with smaller femoral heads. In all 17 THRs, accelerated wear was also associated with thin polyethylene (<6 mm).

This paper highlights a potentially serious problem. When 32 mm metal heads are used with uncemented cups and polyethylene liners, there is a risk of accelerated acetabular wear in patients with thin polyethylene.