LAUSR

BACKGROUND Ulnar or humeral component stem fractures after total elbow arthroplasty (TEA) are serious complications. We hypothesized that TEA stem component fractures are fatigue fractures that result from periarticular osteolysis caused by bushing wear, which leads to a region of unsupported stem adjacent to a region where the stem is well-fixed. METHODS A review of 2637 primary and revision TEA cases from 1972 to 2016 revealed that 47 operations in 46 patients were complicated by or performed to deal with component stem fractures. Bushing wear was graded according to percentage loss of polyethylene thickness and metal wear. RESULTS In the 39 cases in which bushing wear was able to be quantitated, it was severe in 34, moderate in 2, and mild in 3. Radiographs at final follow-up were available in 47 cases. All 47 cases showed evidence of periarticular osteolysis, which was in zone 1 in 17, in zones 1 and 2 in 29, and diffuse in 1. The length of the well-fixed stem, expressed as a percentage of total stem length, averaged 63% (range, 29%-86%). Stem fractures most often (27 of 47 cases) occurred at the junction between the well-fixed stem and unsupported stem. The median distance between the site of stem fracture and the unsupported-well-fixed stem junction was 0 mm (interquartile range, 0-5 mm). CONCLUSION On the basis of our findings, a component stem fracture after TEA seems to occur by fatigue failure at or near the junction between an unsupported stem and well-fixed stem. This area of unsupported stem occurs as a result of osteolysis caused by bushing wear. The solution for component fractures requires a solution for bushing wear.