All wear-measurement techniques assess femoral head penetration and
therefore cannot distinguish between true polyethylene wear and bedding-in.
Multiple wear measurements that are made at different time-intervals after
bedding-in has occurred are required to determine the true wear rate.
Computer-assisted edge-detection techniques offer improved accuracy and
precision compared with manual techniques and appear to be ideally suited for
the retrospective and prospective examination of large groups of patients with
intermediate to long-term radiographic follow-up (more than five years).
While radiostereometric analysis offers improved accuracy and precision
compared with computer-assisted edge-detection techniques, widescale clinical
application is limited because of its relative expense, the required
expertise, and the fact that it can only be used in a prospective fashion.