J Korean Soc Med Ultrasound.  2002 Mar;21(1):65-73.

Usefulness of Diagnostic Ultrasound for Detecting Myofascial Change of the Hamstring Muscles due to Immobilization: Experimental Study with Caged Rabbits

• Kang YK
• Kim JH
• Lee CH
• Kim JR
• Kim HK

Abstract

PURPOSE: To evaluate the usefulness of diagnostic ultrasound in the localization of soft tissue changes in the region of clinically suspected myofascial pain syndrome and to investigate the ultrasonographic and pathologic differences of the hamstring muscles between caged and freely mobile rabbits.
MATERIALS AND METHODS
A total of eight caged rabbits were used in this study. Four rabbits (age: two were 3-4 months, and the other two were 8 -9 months) were raised in a small cage (40 x 50 x 30 cm), and the other four rabbits (age: two were 3 -4 months while the other two were 8-9 months) raised in a yard where they were free to move around. First, clinically identified myofascial trigger pointtaut band or nodule was identified followed by diagnostic ultrasound examination of the hamstring and gluteus muscles and injection of Indian ink of the band or nodule. Biopsies were performed to include the hyperechoic regions as well as clinically identified myofascial trigger points, and the obtained specimens were stained with hematoxylineosin and massontrichrome.
RESULTS
The analysis of the results of the ultrasound study and pathologic study found correlation between the pathologic identification of myofascial trigger point and diagnostic ultrasound, where palpable nodules of caged animal, older more than younger one showed greater extent of increment of echogenecity and degenerative pathologic changes such as fatty changes and appearance of hyaline fibers.
CONCLUSION
Diagnostic ultrasound could be applied to identify or observe soft tissue changes in the regions of clinically identified myofascial trigger points. A pattern has emerged where soft tissue changes were more likely to be observed in the caged animal where their movements were restricted and prone to fixed position. Further study to investigate the reversibility of pathologic changes of caged animal should be carried out.

MeSH Terms

Animals
Biopsy
Hyalin
Immobilization*
Ink
Muscles*
Myofascial Pain Syndromes
Rabbits*
Trigger Points
Ultrasonography*