Is the long head of the biceps related to anterior shoulder pain? A histopathological study

Objectives. Pathologies of the long head of the biceps have been viewed as a source of anterior shoulder pain and disability. Thus, we performed a histopathological and immunohistochemical examination of the biceps tendon with regard to the neuronal structure, the number of mechano[1]receptors and immunohistochemical types, to investigate the relationship of these factors with pain. Materials and Methods. This is a single-center prospective comparative study, on 11 patients divided into Group A (n=5) and Group B (n=6). Patients who underwent arthroplasty due to Neer type[1]4 proximal humeral fractures were selected as the control group (Group A). Group B consisted of patients with chronic anterior shoulder pain who underwent subpectoral biceps tenodesis during arthroscopic rotator cuff repair. The long head of biceps tenodesis was performed in all patients. Results. Hyalinization in the tendon was observed in 2 patients of group B. Chondroid degeneration was found in one patient with hyalinization. Inflammation, calcification, or matrix formation were not detected in any patients. Normal nerve fibers were observed around the tendon in 9 patients with S-100 immunohistochemical staining. In 1 patient, weak staining was observed in the nerve sheath with EMA immunohistochemical stain. No tactile body was detected. Conclusions. We did not observe any histo[1]pathological findings that could be considered the cause of pain in the two groups. Biomolecular and biomechanical studies, in addition to microscopic studies, are needed to explain why the biceps is a potential source of pain.