This study investigated the stereomicroscopy, serial radiographs and histopathological findings associated with 16 semiconstrained total elbow arthroplasty components retrieved at either revision surgery (at a mean of 5 years after implantation) for mechanical failure (15 elbows) or postmortem examination (1 elbow). The average age of the patients at the time of initial arthroplasty was 53 years (range, 32 to 83 years). The time from the index procedure to implant retrieval averaged 59 months (range, 24 to 142 months). The indications for revision surgery included pain, instability, loosening and/or fracture. Although most elbows were considered to have early failure, radiographically the prosthesis exhibited only mild deviation from neutral alignment. In addition, most cement mantles were considered adequate.
Immediate postoperatively, there were very few radiographic lines. However, prior to revision surgery, there was a predominance of cement-bone interface lines and cement-prosthesis radiolucent lines. There were several different patterns of radiolucent lines noted over serial radiographs. In 9 of the 15 elbow joints retrieved at revision and in the stable postmortem elbow, the periarticular soft tissues were grossly grey or had black discoloration representing the presence of metallic debris. Implant analysis exhibited all 4 modes of wear previously described for total hips and knees. The cellular responses to particulate wear debris were similar in most cases. The synovial tissues and implant interface membranes showed chronic inflammation, fibrosis, and focal necrosis associated with abundant intracellular metallic and polymeric particles. There were a marked number of wear particle-laden histiocytes and a moderate number of multinucleated giant cells although polymorphonuclear leukocytes were rare. Titanium alloy wear particles were most abundant in the periarticular implant interface tissues with particles ranging from .1 micron to 30 microns. Polyethylene wear particles were nearly equally as prevalent as the metallic particles and exhibited a wide range of morphology and size.
Despite the Coonrad-Morrey prostheses being implanted for over 40 years, there has been very little examination of modes of wear associated with aseptic loosening following total elbow arthroplasty. This article provides an excellent in depth analysis of patterns of wear associated with total elbow arthroplasty. Most notably, there were multiple modes of wear and several patterns of radiolucencies. Serial radiographic evaluations should be undertaken in patients following total
elbow arthroplasty to identify prostheses at risk with progressive osteolysis. The polyethylene bushings showed significant degradation resulting in substantial unintended contact of the metal components resulting in metal on metal wear particle generation. As previous studies have noted, ulnar implants with polymethylmethacrylate precoat design exhibited suboptimal cement-prosthesis bonding as evidenced by linear longitudinal wear tracks and grossly loose stems at the time of revision surgery.
Although this study is unable to correlate clinical characteristics at the time of implantation with ultimate failure, it does document the radiologic, physiologic and histologic findings associated with aseptic necrosis of total elbow arthroplasties.