Experimental study on the therapy of acute biceps femoris strain with low-intensity electrical stimulation

Abstract

目的:采用低强度电刺激治疗股二头肌 急性拉伤,观察其对肌肉损伤部位结构重塑的影响。方法:雄性SD大鼠36只,随机分为正常对照组和实验组,后者又依取材时间分为D0组、D7组、 D7-20Hz组、D14组和D14-20Hz组,每组6只。各实验组采用电刺激使股二头肌强直收缩,同时以角速度960°.s-1伸膝摆腿反向拉伸,建 立股二头肌急性拉伤动物模型。造模完成后,D7-20Hz组和D14-20Hz于动物造模后第5天开始进行20Hz电刺激治疗,每日2次,每次30分钟, 间隔4小时,其余组继续喂养不做干预。正常对照组在实验开始当天,D0组、D7组、D7-20Hz组、D14组和D14-20Hz组分别在相应时间(实验 当天,第7、7、14、14天)进行在体力矩测试,观测最大等长力矩值以及最优角度。然后处死动物,分离股二头肌,固定、切片、HE染色,光镜下观察股二 头肌组织形态。结果:光镜观察可见,拉伤后第7天D7组肌纤维出现修复,但不成熟,肌纤维排列不严整,大小不一。经过电刺激治疗后,同期的D7-20Hz 组新生的肌纤维更成熟,成簇排列,结构更严整,边界更清晰。第14天D14组和D14-20Hz组两组肌纤维基本修复。D0组关节最大等长力矩值下降至 (0.246±0.026)Nm,与正常对照组(0.337±0.025)Nm比较有显著性差异(P<0.05);D7-20Hz组和 D14-20Hz组关节最大等长力矩值分别与D7组和D14组比较均无显著性差异(P>0.05)。D0组最优角度为144.50°±3.71°, 与正常对照组130.00°±3.54°比较存在显著性差异(P<0.01);D14组在120.00°±3.53°,与正常对照组比较有显著性差 异(P<0.05)。经电刺激治疗后D14-20Hz最优角度出现在125.00°±3.53°,与D14组比较存在显著性差异 (P<0.05)。结论:股二头肌急性拉伤后早期采用低强度电刺激治疗,可有效促进损伤肌肉结构重塑,虽不能在两周内明显提高关节最大等长力矩,但 可优化关节力矩-角度关系。 还原 Objective To observe the effectiveness of low-intensity electrical stimulation for rebuilding of muscle structure.Methods Thirty-six male SD rats were randomly divided into control group,D0 group,D7 group,D7-20Hz group,D14 group,and D14-20Hz group.All rats,except those in control group were anesthetized,and one of their limbs was chosen at random to create a partial biceps femoris stretch injury through knee extending and swing at 960°·s-1.After injury,no interventions were given to D0 group,D7 group and D14 group.At the fifth day,the electrical stimulation protocol(square wave stimuli at 20Hz,30 minutes each time,twice a day with a 4-hour interval) was given to D7-20Hz,and D14-20Hz groups.The isometric maximal knee torque and the optimal angle in control group at the beginning of experiment,and in D0 group,D7 group,D7-20Hz group,D14 group,and D14-20Hz group at beginning of experiment,7th day,and 14th day were tested.The pathological changes in the injured muscles were observed.Results At day 7,injured muscle fibers were recovered,while not matured.At the same time,in D7-20Hz group,the new fibers became more matured,and the neat formation and clear boundary revealed.At day 14,the injured muscle fibers were matured and recovered completely.The isometric maximal knee torque of control group was 0.337±0.025 Nm,significantly reducing by 73.05±5.37% at day 0 post-injury(P < 0.05).Compared to the isometric maximal torque in D7 group,no significant difference(0.312±0.043 Nm) existed in D7-20Hz group(P > 0.05).There were no significant difference between D14 group and D14-20Hz group.The optimal angle of control group(130.00°±3.54°) showed a significant right shift(144.50°±3.71°) at day 0 post-injury(P < 0.01),and those of D14(120.00°±3.53°) were significantly different from that of control group(P < 0.05).After electrical stimulation,the optimal angle of D14-20Hz group was 125.00°±3.53°,and significantly different from that of D14(P < 0.05).Conclusions Low intensity 20Hz electrical stimulation was useful for muscular rebuilding in the injured biceps femoris morphologically and functionally.Though it could not increase the maximal isometric toque,but it was able to improve the torque-angle relationship in injured biceps femoris after 2 weeks of injury.