The effects of free fat grafts on the stiffness of the rat sciatic nerve and perineural scar

We developed a new quantitative rat sciatic nerve model to test whether fre e fat grafts can reduce postoperative perineural scar formation. Epineurect omies of sciatic nerves were performed to create scar. The force required t o distract the nerve a unit distance was measured after surgery to determin e the time of maximal scar formation. Nerve stiffness normalized for rat we ight was statistically greater at 2 months after the initial dissection (0. 097 +/- 0.009 g/mm/g rat weight, n = 10 limbs) than rat limbs that had not undergone a previous dissection (0.075 +/- 0.012 g/mm/g rat weight). Perine ural scar thickness was thicker at 2 months than the perineural tissue in p reoperative controls. Free fat grafts decreased nerve stiffness at 2 months (0.078 +/- 0.012 g/mm/g rat weight) in comparison to the contralateral sur gical control limb without a fat graft (0.094 +/- 0.014 g/mm/g rat weight). Free fat grafts reduced the strength of postoperative perineural scar in t his surgical model; however, they were associated with an unexpected findin g of substantial postoperative neuropathy. (J Hand Surg 1999;24A:30-36. Cop yright (C) 1999 by the American Society For Surgery of the Hand.).