Abstract
We studied six adult male dogs to determine whether free patellar tendon grafts show evidence of reinner vation when used for anterior cruciate ligament recon struction. Histologic return of neural elements and re turn of a somatosensory-evoked potential defined evidence of reinnervation. Before removal, the native anterior cruciate ligament was electrically stimulated with a bipolar electrode and a somatosensory-evoked potential was recorded from a scalp electrode. The ligament was excised and reconstructed using an au togenous patellar tendon graft. Somatosensory- evoked potential was attempted immediately after reconstruction. Histology for nerve endings was per formed on the native ligaments. Each animal under went repeat arthrotomy 6 months later. The grafts were isolated and somatosensory-evoked potentials were attempted. An evoked potential was seen in all six dogs before reconstruction. No graft demonstrated a somatosensory-evoked potential acutely; however, 6 months postoperatively, the somatosensory-evoked potential returned in two cases. Histology of native ligaments showed that 25% of the 100 sections eval uated contained neural elements. Of the receptors present, 89% were mechanoreceptors and 11 % were free nerve endings. Histologic examination of the graft tissue 6 months postoperatively revealed that all six grafts also contained neural elements. Mechanorecep tors and free nerve endings were present in approxi mately equal numbers in the grafts. The results of histology and somatosensory-evoked potential demon strate that in at least some cases, free patellar tendon grafts show evidence of reinnervation when used for anterior cruciate ligament reconstruction.
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