The tendon of the long head of the biceps in complex proximal humerus fractures: a histological perspective.

We have studied the histologic and immunohistochemical changes of the long head of the biceps brachii tendon (LHB) in low-energy complex proximal humerus fractures. Our objective was to detect histological features, which may be correlated to pain generation. Biopsy samples were obtained during hemiarthroplasty procedures from 11 patients who suffered a complex proximal humerus fracture. The control group consisted of 10 samples harvested from human cadavers with no history of premortem shoulder problems and no gross shoulder pathology. Histologic investigation included quantitative measurement of tendon degeneration, cellularity, neoangiogenesis, inflammation and metaplasia, as well as immunohistochemical detection of cells with neural differentiation within the tendon tissue proper with S-100 protein and neuropeptide Y (N-Y). The found lesions were significantly more in the group of tendons from fractures compared to the control group (p<0.001). These lesions were also statistically correlated to each other, indicating a possible neural differentiation of tendon stromal cells. The LHB is a potential source of pain and the routine use of tenotomy/tenodesis of this tendon in hemiarthroplasty procedures for fracture may be reinforced by the results of this study.