Prevention of nerve root adhesions after laminectomy.

In repeat lumbar surgery for failure of the original operation to provide lasting relief, well-organized fibrous tissue is often noted binding together the dura, nerve roots, and erector spinae muscles. Lumbar laminectomy was carried out in 46 dogs and seven groups of animals studied. Gelfoam failed to prevent fibrosis. Free fat grafts prevented fibrosis whether the graft was placed at the laminectomy site or around the nerve roots. Vascularization of the grafts was demonstrated by injection of India ink before sacrifice. Ligamentum nuchae, which is similar to ligamentum flavum in its high elastic content, was also effective in preventing scar formation. The operative biopsy findings at reexploration in four patients who had free fat grafts following laminectomy are presented.