Aim of study is to verify feasibility of peroneal tendoscopy and to clarify the histological structure of peroneal vincula, so formulating a hypothesis regarding their functional role.

Peroneal tendons possess a vascular supply through mesotendineal structures (vincula), previously related to trophic role and healing response; aim of study is to verify feasibility of tendoscopy in evaluating peroneal tendon and vincula and to clarify histological structure of vincula and presence of nervous tissue, so formulating a hypothesis regarding their functional role.

Cadaver study was performed on 8 fresh-frozen ankles, verifying accessibility of endoscope to tendon and vincula; samples from cadaveric vincula were taken; 5 peroneal vincula biopsies were obtained from 5 patients affected by ankle instability, undergoing tendoscopy for chronic lateral ankle pain. Tendoscopy was performed for persistent pain at the posterior margin of lateral malleolus after at least 4 months of nonoperative treatment. Biopsies were taken from center of pathologic vincula.

Patients biopsies and cadaveric samples were analyzed with light microscopy and immunohistochemistry (anti-humanS100antibody)

Peroneal tendons are accessible by endoscope along whole common sheath; vincula were found in all cadaveric specimens; intraoperative finding of vincula lesion (thickening/scarring) was found in all patients biopsies. Histology and immunohistochemistry revealed presence of nervous fibers inside the intimate structure of peroneal vincula both in cadaveric specimens and in patients biopsies.

Tendoscopy as a useful tool in visualizing the entire length of peroneal tendons, allowing the surgeon to diagnose and treat different peroneal disorders.

Although literature provides no data about innervations of peroneal vincula, presence of free nervous fibers inside vincula structure is consistent with a proprioceptive role of the vinculum in peroneal tendon physiology.

Moreover, our findings in patients biopsies suggest lesion of peroneal vinculum is a nociceptive source and an important element leading, synergistically with other soft tissues (i.e. joint capsule, lateral ligaments) injuries, to proprioception impairment in clinical pictures of chronic ankle instability. So selective excision of degenerated areas of vincula can be justified as accessory procedure in treatment of chronic lateral pain in patients affected by chronic ankle instability.

Aims: Peroneal tendons possess a vascular supply through a mesotendineal structure named vinculum; vincula are identifiable with tendoscopy and are supposed to play a role in tendon healing response, due to prominent vascularity; aim of the study is to verify the feasibility of tendoscopy in evaluating peroneal tendons, to clarify the histological structure of peroneal vincula and to investigate the presence of nervous tissue, so formulating a hypothesis regarding the functional role of vincula.

Methods: cadaver study was performed on 8 fresh-frozen ankles; dissection were conducted to verify accessibility of endoscope, proximity with superficial peroneal nerve and presence of vincula; samples of vincula were obtained; light microscopy and immunohisto-chemistry (anti-human S100 antibody) were performed, describing structure of vincula and identifying peripheral nerve fibers.

5 peroneal vincula biopsies were analyzed from patients affected by ankle instability and undergoing tendoscopy for peroneal tenosynovitis.

Results: peroneal tendons are accessible along the whole common tendon sheath and a discrete distance between the endoscope and the superficial peroneal nerve is present in all specimens; a membranous mesotendineal structure was found in all specimens between both tendons and tendon sheath; macroscopic inspection revealed the presence of a vessel network, arising from the sheath toward the tendon; light microscopy of cadaver samples confirmed the presence of multiple vessel branches crossing the entire structure of the vinculum and identified nervous structures close to the vessels, resembling a neurovascular bundle; immunohistochemical analysis revealed nerve fibers in each specimen;tendoscopy in patients affected by ankle instability showed lesions of the vincula and histology from intraoperative biopsies showed presence of nerve fibers.

Conclusions: tendoscopy is a useful tool to visualize peroneal tendons and to diagnose and treat different disorders; although literature provides no data about innervations of peroneal vincula, the study shows nervous fibers consistently present inside the intimate structure of vinculum; besides its function in repair and healing processes, this suggests a proprioceptive role of the vinculum in peroneal tendon physiology and lesion of vinculum could be an important element acting synergistically with joint capsule and surrounding tissues lesions and ultimately leading to clinical pictures of ankle instability.