Improving the Clinical Performance of Total Elbow Replacements

Investigators

Douglas E. Padgett, MD; Timothy Wright, PhD

Scope

Clinical success of elbow replacement is poor in comparison to hip and knee replacement. Nearly a third of patients suffer failure within seven years. Mechanical problems, including loosening and bushing wear, are leading causes. We hypothesize that mechanical failure is related to large functional loads (particularly varus moments) to which the bone-implant system is subjected during daily activities. To test this hypothesis, we will analyze a large number of retrieved elbow replacements gathered as part of an ongoing implant retrieval program. Analysis will include subjective grading of wear and damage on the basis of type, severity, and location on the components. Damage patterns will be sought that correlate to radiographic findings of loosening and wear and, more importantly, to particular types of external loads. Relationships with other demographic data will be sought to establish clinical factors that influence performance. The results will form preliminary data for a study intended to combine patient kinematics with a computational elbow model to determine joint loads. These loads in turn will form inputs for finite element models to determine stresses associated with implant fixation and bearing wear. Our goal is to improve performance through rational design changes based on understanding expected failure mechanisms.

Contact

Timothy Wright, PhD
wrightt@hss.edu