The pros and cons of using larger femoral heads in total hip arthroplasty.

With the introduction of improved bearing surfaces for total hip arthroplasty (THA) has come a reintroduction of larger femoral heads with the promise of reducing the rate of hip instability and increasing hip range of motion (ROM). The size of femoral heads used for THA ranges from 22 to 40 mm, and even larger heads are used for hip resurfacing. With accurately positioned components, larger heads reduce the hip instability rate and theoretically increase hip ROM. However, for any given bearing surface, the volumetric wear rate is higher for larger heads than for smaller heads, which potentially jeopardizes the long-term survival of these reconstructions. In this article, we review the evidence for use of larger femoral heads with respect to stability, ROM, impingement, wear rate, bearing surfaces, and future directions.