This study presents a new theory to explain misalignment, relative fixation, and the neurologic manifestation of a contractured or functional leg length inequality in the atlas subluxation complex.
The proposed mechanism of fixation involves impingement/extrapment of the atlanto-occipital intra-articular fat pad causing nociception and reflexive guarding contraction of the suboccipital muscles. Stimulation of spindles in the suboccipital muscles are hypothesized to be involved in the initiation of tonic neck reflexes that alter global extensor muscle tone to achieve proper body balance in response to head movement. This altered muscle tone caused by the tonic neck reflexes is hypothesized to be responsible for the clinical finding of a contractured or functional leg length inequality associated with atlas subluxation complex.
Short reviews of other theories in which atlas subluxation complex results in leg length inequality - dentate ligament/cord distortion and proprioceptive/mechanoreceptor insult - are provided, clinical correlations with the new theory are noted, and potential methods by which to test this new theory are outlined.
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