OPTOELECTRIC MEASUREMENT OF CHANGES IN LEG LENGTH INEQUALITY RESULTING FROM ISOLATION TESTS

Objective: a) Establish a precise, standardized method to assess prone leg alignment changes (functional ''leg length inequality''), which h ave, until now, been reported clinically to occur as a result putative chiropractic subluxation isolation tests [neck flexion (C5) and exten sion (C1)]; and b) describe differences in leg alignment changes in a group of healthy subjects and patients with chronic spinal complaints. Design: Two group, two isolation tests, descriptive, repeated measure analysis of variance. Setting: Exercise and Sport Research Institute, Arizona State University. Participants: Eight healthy controls, eight patients with a history of chronic spinal complaints and observable l eg alignment reactivity. Interventions: Active cervical flexion/extens ion maneuvers. Outcome Measures: Optoelectric markers affixed to heels and occiput, as subjects lay prone. Marker locations sampled at 100 H z for 10 sec during: a) three no movement trials, b) three cervical ex tension and c) three flexion trials. Data transformed to local referen ce frame approximately each subject's longitudinal axis prior to analy sis. Results: Heel position movement occurred during trials and were h ighly individualistic. Patients exhibited more asymmetrical movements than the controls during the head-up trials. No differences existed be tween controls and patients for range of heel displacement or net disp lacement. Conclusions: The results of this study allow the following t o be concluded: 1) small leg displacements (<1 mm) were recorded by th e optoelectric measurement system; 2) heel position changes during iso lation tests were identifiable; 3) as a result of head-up maneuvers, p atients exhibited more asymmetrical heel movement than controls (t = 8 .743, p < .01); 4) The heel range of motion was not different between the groups; and 5) The net change in heel position was not different b etween the groups. Patients exhibited more asymmetrical heel motion du ring head-up isolation tests, suggesting that some phenomena may separ ate these two groups, warranting future study.