J Manipulative Physiol Ther. 1988 Oct; 11(5): 396-9.

Reliability of the Derifield-Thompson test for leg length inequality, and use of the test to demonstrate cervical adjusting efficacy.

Shambaugh P, Sclafani L, Fanselow D.

New York Chiropractic College Research Division, Glen Head 11545.

The Derifield-Thompson test for leg length inequality (LLI) is commonly used by chiropractors to assess a need for adjustment and to evaluate the results of adjustment. The two previous studies testing the reliability of the technique reported conflicting results. This study had two objectives: to demonstrate inter- and intraobserver reliability in detecting a LLI as little as 3 mm; and to document what effect Pierce-Stillwagon cervical adjusting has on a functional LLI. Twenty-six subjects walked into five successive examining rooms where a Derifield leg check was performed, including an estimate of the millimeters of difference in leg lengths. The subjects then entered a treatment room where they were randomly given no treatment, cervical adjusting, or gluteal massage. This process continued for 5 cycles. This study demonstrated that clinicians could reliably measure a LLI to less than 3 mm (both inter- and intraobserver), and also detect a change in LLI when the head was rotated. Neither cervical adjustment nor gluteal massage produced a significant change in observed LLI.