Prevention of epidural adhesion after laminectomy by a salvia miltiorrhiza radix-gel

Ji CHEN; Deming XIAO; Hongtu YANG; Bowen LIN; Wanxin ZHEN; Weifan LI; Meng Lü

ABSTRACT

BACKGROUND:

Different methods and biomaterials have been applied in animal experiments and clinical practice to prevent the formation of epidural scars,Biodegradable and sticky semi-fluid gels are the most often used material.Salvia miltforrhiza radix (SMR) and carbomer have been clinically confirmed to be the safe and effective drugs and gel agents.

OBJECTIVE:

To observe the effect of SMR-gel on preventing epidural adhesion after laminectomy.

DESIGN:

A complete randomized grouping design, a controlled experiment.

SETTING:

Department of Orthopaedics,Shenzhen People's Hospital (Second Clinical College of Jinan University). MATERIALSThirty-six healthy pure New Zealand rabbits were used,either male of female,clean degree,2-3 years of age. They were randomly divided into four groups with 9 rabbits in each groupblank control group,gel contro group, HA group and SMR-gel group. Carbomer934 powder (Shanghai People's Pharmaceutical Factory, batch number 20000510) , hyaluronic acid (HA) [Shandong Bausch & Lomb Freda Pharaceutical, Co., Ltd.,No.H10960136,2 mL (20 mg)].

METHODS:

The experiments were carried out in the animal laboratory of Shenzhen People's Hospital from April 2002 to August 2003.①Preparing SMR-gelSMR was prepared into extract powder.Carbomer934 powder was added by water for dissolving and swelling and stayed overnight,then SMR-gel was prepared by dipping with triethanolamine,adding with SMR extract powder (2 g),then adding with purified water till 100.0 g and stirring uniformly.②The rabbits were anesthetized. and the lamina of vertebra was totally resected at L3 and L6 (reserving superior and Inferior articular processes).then defects of 10 mm×5 mm were made to expose the dura mater.The vertebral defects were added with 1 mL carbomer gel, 1 mL HA (20 g/L) and 1 mL SMR-gel in the gel control group,HA group and SMR-gel group respectively.whereas nothing was added in the blank control group.③Gross samplesThree rabbits were killed 4,6 and 8 weeks postoperatively in each group.vertebraI ventral fascia were stripped to remove the spinal segments (L3,L6) for operation completely,and totally 24 samples for each time.One sample was selected in each group 4 weeks postoperatively. and the samples were observed under H-600 transmission electron microscope (Hitachi). ④The adhesion compactness of scar tissue with dura mater was evaluated in the 24 samples of the 4 groups at 8 weeks postoperativelyThere were 4 gradesNo obvious adhesion between dural sac and scar tissue for grade OExtensive and compact adhesion between dural sac and scar tissue. impossible blunt dissection between dural sac and scar tissue.incomplete dural sac after sharp dissection for grade Ⅲ.Each spinal segment was cut into 4 parts equally,and all were prepared into sections and stained,then the thickness of epidural scar was determined with Tiger2000 image analyzer. ⑤The rank sum test was used in the scar adhesion compactness grading evaluated with naked eyes,whereas analysis of variance.and two-two comparison were used in analyzing the thickness of epidural scar.P＜0.05 was considered as significant difference.MAIN OUTCOME

MEASURES:

①Results of gross scar adhesion compactness grading at 8 weeks and comparison of the thickness of epidural scar at 4.6 and 8 weeks;②Results of gross observation,histological examination and ultrastructure.

RESULTS:

All the 36 rabbits were involved in the analysis of results. ①Results of gross observation and pathohistological examinationThere was compact adhesion at each time point in the blank control group,part adhesion in the gel control group and HA group, and no obvious adhesion in the SMR-gel group.②Results of quantitative

analysis:

The rabbits with lower scores of scar adhesion compactness grading In the blank control group,gel control group and HA group were obviously fewer than those in the SMR-gel group (W=45-52,P＜0.05-0.01).The scar thickness at 4 and 8 weeks in the SMR-gel group was obviously less than that in the other 3 groups(F=128.657,152.246,80.891,P＜0.01).③Results of observation under transmission electron microscopeThe proliferation of fibroblasts at 4 week was active in the blank control group,gel control group and HA group,but inactive in the SMR-gel group.

CONCLUSION:

①SMR can inhibit the fibroblasts to proliferate,differentiate and synthetize into secretory collagens,and then inhibit the formation of epidural scar adhesion.②HA can be absorbed by organs very early,which reduces its role in preventing adhesion.Whereas carbomer gel can stay longer, and it plays a role in inhibiting and blocking adhesion in the whole process of wound repairing.