Peripheral nerve regeneration inside collagen-based artificial nerve guides in humans

Purpose: Nerve gap injuries may be associated with lesions in other structures, like tendons or bones; in these cases, it is common to plan a second surgery to improve functional recovery. Since macroscopic observations of nerve regeneration in humans are rare, we exploited these second surgeries for the purpose of studying nerve regeneration in humans. Methods: We assessed the clinical outcomes of 50 implants of collagen-based nerve guides in the upper limb. We performed a second look at 20, assessing macroscopically both nerve regeneration and collagen degradation. Results and Conclusions: Pain was never recorded in these patients. An adequate sensory recovery took place whenever nerve regeneration was found inside the guide. Motor recovery seemed to occur only when the gap lesion was shorter than 10 mm. The degree of degradation appeared to be variable and was not directly correlated with time; we hypothesize that it could be associated with the site of implantation. Such a large number of second looks in humans has never been previously reported in the literature.