Precise measurement of functional leg length inequality and changes due to cervical spine rotation in pain-free...

A series of blinded studies to determine the feasibility of documenting functional leg length inequalities and changes in functional leg length in normal and non-normal patients were performed. A new apparatus designed to minimize or eliminate subjective components of inequality assessment, while attaining high levels of precision, was developed. Subjects were evaluated for presence of cervical spine lesion by five independent examiners and grouped into "lesioned" and "nonlesioned" categories. Subjects' leg length inequalities were measured by different evaluators as well as multiple measurements by a single evaluator to determine interrater and intrarater reliability coefficients. Measurements were taken on both flat and hi-low tables for changes during active cervical spine rotation. In addition, leg length measurements were taken during induced tetanic contraction by ipsilateral galvanic paravertebral muscle stimulation. Results indicated an absence of any significant effect of head rotation, type of table, galvanic stimulation, or any difference between persons classified as cervically lesioned or not cervically lesioned. Interrater and intrarater reliability coefficients for the measuring apparatus were statistically significant with small error variances. Failure to obtain subjects with frank pain as well as absence of an applied cephalad pressure (as is performed clinically) during leg length evaluation were considered as possible explanations for the failure to detect an effect of head rotation in the leg lengths. Discussion addresses the need for sensitive leg length inequality assessment techniques which eliminate subjectivity and contribute to decreased error variances.