Establishment of a Rat Model to Investigate the Effect of Posterior Lumbar Spine Surgery on Back Muscles

In posterior lumbar spine surgery, the parspinal muscles must be stripped from their attachments to the bones. The changes to the muscles that result are a possible reason reason for persistent back pain. However, it is impossible to obtain back muscle samples serially after surgery in humans. In this study, we sought to establish a rat model to investigate sequential changes in the back muscles after posterior lumbar spine surgery. Twenty-one skeletally mature Wistar rats were used to determine which of two stripping methods was more suitable for establishing an animal model. The limited stripping method simulated the exploration process of a laminectomy; the extensive stripping method simulated intertransverse process fusion. The multifidus and longissimus muscles were takenfor histological examination from a control group as well as experimental groups two, six, or twelve weeks after surgery. No change was noted in the longissimus muscles of either the limited or extensive stripping group. The multifidus muscle in the extensive stripping group showed atrophy of the musclefibers six weeks post-operatively and progressive fibrosis over the stripping area up to twelve weeks after surgery. The multifidus muscle in the limited stripping group atrophy of the muscle fibers with fibrosis in three rats two weeks after surgery. Six weeks after surgery, hypertrophic fibers with increased acidic ATPase density, angular fibers and grouping of Type 1 fibers were noted. Twelve weeks after surgery, large areas of Type 1 fibers of varying diameters were noted. These findings are comparable to a diagnosis of neurogenic myopathy resulting from a denervation-reinnervation process and are similar to findings reported in human patients. The limited stripping method is more suitable than the extensive stripping method as a rat model simulating post-operative changes on human multifidus muscle.

並列關鍵字

Rat model ； Posterior lumbar surgery ； Multifidus ； Denervation-reinnervation

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