Changes in apparent leg length (LL) (leg\u00a0 retraction) have been used by many as a means of locating subluxation in\u00a0 various joints. The leg check is based on the assumption that unequal\u00a0 muscular contraction (e.g. hyper irritable muscles) about the spine and\u00a0 pelvis have the ability to retract one leg relative to the other.\u00a0 Despite claims of usefulness, many problems are inherent in the prone\u00a0 leg check such as: a) measurement error; b) subject positioning by the\u00a0 examiner (expectancy bias); c) interference with the surface of the\u00a0 examination table; d) possible overwhelming effects of large muscles\u00a0 over smaller intersegmental muscles and; e) lack of information of the\u00a0 validity of subluxation (eg. segmental aberration) and it\u2019s supposed\u00a0 neurological effects. While observation of leg retraction has not yet been\u00a0 correlated with patient outcome or health measures, it is implied that\u00a0 the phenomenon apparent changes in LL occur due to altered tonic neck\u00a0 and back reflexes which coordinate spinal movements and posture. A video\u00a0 recording has been made of a patient who exhibited an unusually large\u00a0 amount of leg retraction which appeared to be due to asymmetrical\u00a0 contraction of their supra-pelvic musculature upon maneuvers such as\u00a0 tucking their chin.<\/p>\n
The purpose of this study is to quantify\u00a0 the involuntary movements which nave been observed about the spine,\u00a0 pelvis and extremities using a 2D motion analysis system.<\/p>\n
A subject exhibiting a large involuntary leg\u00a0 retraction will be sought. The patient will be positioned prone on an\u00a0 adjusting table. Retro reflective markers will be placed about their\u00a0 spine, pelvis and extremities. The markers will be recorded by two video\u00a0 cameras during maneuvers which cause the leg to retract.<\/p>\n
This data will yield 2D maker locations which will be used to quantify the amount and type of movement.<\/p>\n
Despite claims of utility of the prone leg\u00a0 check to locate subluxation and treatment success, many confounders\u00a0 occur. Lack of objective documentation and theoretical basis of the leg\u00a0 retraction phenomena has hindered its acceptance as an examination\u00a0 procedure. Only indirect evidence exists for its validity in several\u00a0 small observational studies where it was used to determine were to\u00a0 adjust. Motion analysis, and EMG studies may help in understanding the\u00a0 physiology of this phenomena using. Further work is necessary to\u00a0 correlate the relationship of leg retraction to other methods of\u00a0 subluxation assessment, treatment outcome and patient health status, if\u00a0 any.<\/p>\n
Reference:<\/strong> Paul J. Osterbauer,DC; Arlan W. Fuhr,DC. Proceedings of the California Chiropractic Foundation\u2019s 7th Annual\u00a0 Conference on Research and Education, June 19-21,1992; pp.291-292.<\/p>\n