OBJECTIVETo observe the histologic changes of the cervical muscles and intervertebral discs caused by dynamic dysequilibrium of frontally cervical muscles in rabbits.

METHODSThirty healthy rabbits with an average age of two years, half males and half females, the mean of weight in (2.75 +/- 0.25) kg, were divided randomly into model group and the sham operation group with fifteen rabbits in each group. The hibateral sternocleidomastoid muscles of rabbits in the model group were shortened by medical pipe to estabish the new animal model (the model was cervical dynamic dysequilibrium); and in the sham operative group, only exposed hibateral sternocleidomastoid muscles by operation. At the same time after two months, the histologic changes of the cervical muscles and intervertebral discs in all rabbits were observed, meanwhile, the myofibrillar amount and its cross section area were compared between two groups.

RESULTSAfter operation, the cervical muscles and intervertebral discs had significant change in model group, but no obvious change in sham operative group. The myofibrillar amount of frontal cervical muscles and back cervical muscles in model group was obviously lower than that of sham operative group (P < 0.05); likewise, the myofibrillar cross section area in model group was obviously lower than that of sham operative group (P < 0.05); the frontal cervical muscles was obviously change than the back cervical muscles.

CONCLUSIONThe cervical dynamic dysequilibrium caused by crispation of frontal cervical muscles can lead to pathologic degeneration of cervical muscles and intervertebral discs. The study may provide experimental proof for early cervical spondylopathy.