Patient factors and wear in total hip arthroplasty.

Polyethylene wear in vivo is multifactorial including numerous patient factors, such as gender, age, and activity. There are limitations in the clinical assessment of some of these factors and, for this reason, surrogate variables are used. For example, patient age and diagnosis frequently are used as surrogates for patient activity. The most variable and difficult factor to quantify is the frequency and intensity of use of the prosthesis during the service life of the arthroplasty. The clinical evaluation of patients with a total hip arthroplasty would be enhanced by a standardized assessment of the frequency and intensity of patient activity as it relates to the use of the prosthesis.