Effect of straight-leg-raising movement on epidural fibrosis in early stage after laminectomy in a rabbit model.

To determine the effect of straight-leg-raising (SLR) movement on epidural fibrosis after laminectomy, 40 adult New Zealand rabbits were selected as laminectomy models in the study. They were divided into 2 groups: a SLR group (group S) and a control group (group C) randomly, with each group having 20 animals. All rabbits were subjected to total laminectomy in the site of S1. Every 5 rabbits in each group selected randomly were killed at the 1st, 2nd, 4th, and 8th week after the surgery. Segments of spines from L7 to S2 were removed en bloc. After gross evaluation, specimens were sliced up. The slices were stained by HE and Masson's trichrome methods respectively for histological examination. Our results showed that formation process of scar in group S was retarded as compared with that of group C at the time of the 2nd-week, but there was no statistical difference between groups in the adhesion degree (P> or =0.05). At the 4th and 8th week, the epidural fibrosis of group S was more serious than that of group C. Since the 2nd-week, the area of scar in group S was larger than that of group C. The number of fibroblasts and inflammatory cells in group S were larger than those of group C at early stage. But in later stage, there was no statistical significance between the two groups. It is concluded that SLR movement after laminectomy may promote the formation of epidural fibrosis and retard the maturity of scar. SLR movement can also aggravate scar adhesion.