Martha Hoque

Cushion Form Bearings in Total Hip Arthroplasty: Nature’s Approach to the Synovial Joint Problem

Over the past 40 years, metal-on-polyethylene bearings have been the most extensively used in total hip replacement. These implants do not permit lubrication, and wear of the articulating surfaces occurs as a consequence. Ceramic-on-ceramic bearings are associated with squeaking and the potential risk of breakage. Furthermore, the ceramic head is smaller than the patient’s original head size. With metal-on-metal bearings, the patient’s original head size can be replicated, but serum metal ion elevation is a potential problem. There now exists a novel type of bearing for use in total hip arthroplasty, which includes an uncemented acetabular component made from polycarbonate-urethane. This material biomechanically replicates human cartilage, is hydrophilic, thus allowing fluid film lubrication which in turn reduces wear, and it can be coupled with large diameter metal heads.