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Histopathological nature of myofascial trigger points at different stages of recovery from injury in a rat model

PainSci » bibliography » Zhang et al 2017

Two articles on PainSci cite Zhang 2017: 1. The Complete Guide to Trigger Points & Myofascial Pain2. Muscle Pain as an Injury Complication

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

OBJECTIVE: To investigate the histopathological nature of myofascial trigger points (MTrPs) or spots (MTrSs) at different stages of recovery from injury in a rat model.

METHODS: Forty Sprague-Dawley rats were randomly divided into two groups: a control group (CG) and experimental group (EG). The CG was further randomly subdivided into CG1 and CG2 subgroups. The CG2 was used for palpating the taut band and CG1 as a blank. EG was subdivided into three groups according to recovery times: 4 weeks (4W), 8 weeks (8W) and 12 weeks (12W); these groups consisted of eight rats each. All CG rats received no intervention, whereas the intervention in EG rats was by a blunt strike to the vastus medialis and eccentric exercise for 8 weeks. The taut bands with spontaneous electrical activity were then detected in the muscle to guide a muscle biopsy. The histopathological findings were investigated under optical and electron microscopes in all groups.

RESULTS: Under optical microscopy, the differently augmented sizes of round fibres (contracture knots) with deep staining in the transverse section and fusiform shapes in a longitudinal view were clearly seen in CG2 and EGs with a large diameter; the number of contracture knots was significantly more in EGs than in CGs. Under an electron microscope, the mitochondria in EGs significantly decreased with abnormal structures. The sarcomeres were significantly shortened in the 8W and 12W EGs.

CONCLUSION: An injury can cause activation of MTrSs in a muscle and an activated level of MTrPs depending on the number of contracture knots in muscle with impaired energy production.

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