Evaluation of hyaluronic acid sheet for the prevention of postlaminectomy adhesions.

BACKGROUND CONTEXT: Various materials have been tested for their ability to maintain a barrier between muscles and epidural space in order to physically or chemically inhibit scar ingrowths. Hyaluronic acid (HA) solution and gel have been reported to be effective in preventing adhesions postlaminectomy; however, neither has been used clinically after spinal surgery. PURPOSE: To determine the efficacy of HA sheet for the prevention of postlaminectomy adhesions compared with that of HA gel or another sheet. STUDY DESIGN/SETTING: An animal model of lumbar laminectomy in rabbits was used to study postoperative scar tissue formation around the spinal cord. The histologic effects of HA sheet were compared with those of Gelfoam (GF) and further evaluated by an inflammation model using rhTNF-alpha. PATIENT SAMPLE: Rabbit. OUTCOME MEASURES: Histologic examination. METHODS: Five rabbits were killed at 2, 4, 8, and 24 weeks after laminectomy, respectively. Another 18 rabbits were examined in an environment of active inflammation experimentally induced by rhTNF-alpha to compare the effects of HA sheet with those of GF or HA gel. Histologic examination was performed to quantitatively assess invasive scar formation or inflammation postlaminectomy, and then, the histologic effects of HA sheet were compared with those of GF or HA gel. RESULTS: In the HA group, significantly, the area of subarachnoid space was larger, distance from the surface of dura to scar tissues was greater, the number of inflammatory cells in the scar tissues at the site of laminectomy was less, and enlargement of dura was suppressed. Using an inflammation model, we also demonstrated the efficacy of HA sheet treatment. CONCLUSIONS: In an experimental laminectomy model, HA sheet formed a solid interpositional membrane barrier and exhibited anti-inflammatory activity. Further investigations will be needed for HA sheet to be used clinically.