The "bicipital aponeurosis flex test": evaluating the integrity of the bicipital aponeurosis and its implications for treatment of distal biceps tendon ruptures.

Background: One mitigating factor in the accurate diagnosis of complete distal biceps tendon ruptures (DBTR) is the integrity of the bicipital aponeurosis (BA). Current orthopedic literature lacks a descriptive means of evaluating the integrity of the BA in the presence of distal biceps injury.

Methods: A consecutive cohort of 17 patients with suspected DBTR was examined. The hook test, passive forearm pronation test, and the biceps crease interval (BCI) test were performed as part of the overall clinical examination to assess the integrity of the distal tendon. The biceps crease ratio (BCR), a component of the BCI test, was used as an objective measure of distal tendon retraction. Integrity of the BA was assessed using the "BA flex test." The status of the distal tendon and BA were confirmed intraoperatively.

Results: Sixteen patients had complete rupture of the distal biceps tendon. One had a high-grade partial thickness tear. The BA remained intact in 59%. Application of the BA flex test resulted in 100% sensitivity and 90% specificity, with overall diagnostic accuracy of 94%. Despite complete DBTR, there was a significant difference in the amount of distal tendon retraction (P = .012) between those with the BA intact (median BCR, 1.5, interquartile range, 1.3-1.9) and those where the BA was absent (median BCR, 2.2, interquartile range, 1.7-2.6).

Conclusion: Evaluating the integrity of the BA can help to inform evaluation and treatment of DBTR, especially when visible or palpable alterations in biceps contour and proximal tendon migration are absent or equivocal.