"The effect of neuropathy on healing of the medial collateral ligament was studied in rats that
had undergone surgical sympathectomy (autonomic neuropathy) or femoral nerve transaction (sensory neuropathy)40. There were significant decreases in various neuropeptides, such as substance P, calcitonin gene-related peptide, and vasoactive intestinal peptide, in the denervated tissues. Impaired healing, demonstrated by significant decreases in failure force of the healing ligaments, was seen in both groups of rats."