Suture anchor reinsertions of distal biceps rupture: a histological analysis of torn tendon and clinical results at short- and long-term follow up.

BACKGROUND: Distal Biceps Brachii Tendon (DBBT) rupture is a relatively rare injury. Nonsurgical treatment determines 30-40% power loss of elbow flexion and up to 50% of forearm supination. Therefore, re-fixation of the DBBT is recommended. DBBT is exposed to tension and compression loading. It is known that tendon under compression might develop fibrocartilaginous metaplasia that improves the resistance to compression but reduces the resistance to tension. To test this hypothesis, the present study evaluated the presence of cartilage in DBBT samples. Furthermore, the present study evaluated the clinical and functional outcomes of anatomic reinsertion through suture anchors in a cohort of patients after 1, 3 and 5 years of follow-up.

METHODS: Between 2011 and 2014, twenty-one patients with DBBT tear underwent a suture anchor reattachment. Histochemical and immunohistochemical analysis of torn samples of DBBT collected at the time of surgical repair were performed to test the presence of cartilage. During the follow-up examination, mobility, elbow radiographs, Mayo Elbow Performance Score (MEPS) and isokinetic analysis were prospectively evaluated.

RESULTS: Fibrocartilage was detected in all tendon samples collected. Two cases of transient paresthesia in the lateral antebrachial cutaneous nerve occurred, but they solved in 6 weeks. There were not vascular deficit, re-ruptures, radio-ulnar synostosis or infective complications at follow-up. Three patients reported loss of supination. MEPS showed good and excellent clinical and functional results. Not significance differences about strength and fatigue in flexion-supination were recorded between surgical and contralateral side at 3 and 5 years of follow-up. Arm dominance influenced supination but not flexion.

CONCLUSION: On the basis of our results, the presence of cartilage metaplasia might make DBTT at higher risk of rupture assuming the compression loading and the hypovascular zone of the tendon. However, concerning the lack of histological analysis of healthy DBBT, its role in tendon pathology remains to be clearly defined. The technique of suture anchor reinsertion by single incision was shown to be safe, with few complications and good functional results at 5 years of follow-up. No significance differences were reported between injured and non-injured side in terms of flexion and supination isokinetic analysis, while arm dominance had a positive effect on supination.