Prevalence of amyloid deposition in distal biceps tendon ruptures: a retrospective review of intraoperative biopsy.

Background: In a previous study, one-third of patients with heart failure secondary to wild-type transthyretin amyloidosis were found to have distal biceps tendon (DBT) ruptures, and a large proportion of these ruptures were spontaneous or asymptomatic. This rate is higher than the 2.5% incidence of DBT ruptures seen in patients with other causes of heart failure. DBT ruptures can be used as a screening opportunity for early detection of systemic amyloidosis. However, when a subsequent study investigated the rate of amyloid deposition in 30 patients with acute DBT ruptures, only 3% had evidence of amyloid deposition. Although that study was powered to detect a DBT rupture prevalence of 33%, we suspect the real prevalence of amyloid deposition in patients presenting with DBT ruptures is lower, and a higher-powered study would help to better understand the role of intraoperative biopsy of DBT ruptures for systemic amyloidosis screening. Methods: This study is a retrospective review of 53 patients with DBT ruptures who underwent operative repair at a single institution between June 2022 and June 2024. At the time of surgery, a tissue sample was taken from the DBT and sent as a specimen for evaluation. Specimens were reviewed by board-certified pathologists under microscopy, and Congo red staining was performed to evaluate for amyloid deposition. Specimens that stained positive for amyloid were sent to an outside facility for liquid chromatography tandem mass spectrometry for confirmation and subtype identification. Patient demographic data were collected by a retrospective chart review. Results: Of the 53 included patients, 4 (9.43%) were positive for amyloid deposition on Congo red staining and liquid chromatography tandem mass spectrometry. No patients had a diagnosis of amyloidosis or cardiac manifestations of amyloidosis at the time of repair. Conclusion: Intraoperative biopsies of DBT ruptures may be a valuable tool for early detection of amyloid deposition.