Young-Min Kwon, MD, PhD
Alister Hart, FRCS, of Royal National Orthopaedic Hospital in London, first reviewed what retrieval studies, involving 5,000 components from 22 countries, reveal about implant complications. He described such forensic analysis as akin to study of the black box from an airplane after a crash, providing clues to questions such as: What is the human wear rate? What surgical, design, and patient factors influence wear rate? How does the wear occur?
- Implant only—component size mismatch
- Intraoperative details—loosening, soft-tissue findings, impingement
- Clinical and blood details—to correlate laboratory tests with other clinical parameters
- Imaging—to distinguish between surgical and design factors
- Registry studies—“the ultimate method of understanding implant performance”
Moderator Young-Min Kwon, MD, PhD, of Massachusetts General Hospital, explained that evaluation of a painful MoM hip should take a systematic approach that includes the following:
- clinical history and physical examination
- testing of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)
- measurement of metal ion levels
- cross-sectional imaging, such as metal artifact reduction software (MARS) MRI
Craig J. Della Valle, MD, of Rush University, also addressed the diagnostic challenges in MoM hips, particularly as they relate to periprosthetic joint infections (PJIs). “The intra-operative appearance may mimic purulence, and cell count may be likewise unreliable,” he said.
Tuesday through Friday, March 11 – 14, 2014.