BACKGROUND AND OBJECTIVE
The prone comparison of changes in leg alignment is commonly used to identify musculoskeletal dysfunction by chiropractors. Despite its widespread use as a diagnostic tool, confusion exists about the reliability of these measures. A possible problem is this methods dependence upon the clinician to accurately assess leg length asymmetries by visual inspection. The purpose of this investigation was to utilize a precise optoelectric device to determine 1) Leg length asymmetries prior to and after a random series of isolation tests, and 2) Heel trajectories during the performance of these isolation tests.
-Four subjects were tested in the Motor Control Laboratory at ASU. During each testing Session the subjects lay prone on a portable adjusting table with infrared light emitting diodes affixed with adhesive to their posterior heels, and posterior occiput. Additional markers were placed on a moveable reference bar placed near the subject’s feet. The reference bar was aligned to be perpendicular to the body, and was independent of the adjusting table. Prior to any data ‘Collection, each patient was assessed visually by a chiropractor for the incidence of any leg length inequality, which was recorded for later use. After the visual assessment, the reference bar was placed at its permanent location, and a second leg length measurement was made by a second investigator by measuring marker location of each heel from the bar with a scale marked in millimeters. Each measurement (visual and from the bar) were kept blind from the other respective investigator. Data collection then proceeded with the optoelectric device. Data were collected for 8 seconds at 50 Hz during the following conditions: no movement, head-up, chin-tuck, pressure test right transverse process of C-1, or pressure test left transverse process of C-1, The initial 5 trials were in the order mentioned in the prior sentence; 5 trials of each condition were then collected in a randomized order for a total of 30 trials. After all data were collected, leg length assessments were carried out by the two investigators as was completed prior to data collection. After data collection was complete, digital data were filtered at 2 Hz and 0′ rotated mathematically into a local reference frame within which the bar represented one axis in a 3-D frame. This allowed measurements to be examined along an axis perpendicular to the bar, the expected axis of lengthening or shortening of each leg. Two types of analyses were completed for each subject. Leg length difference analysis consisted of examining the heel positions at the; beginning and end of the entire testing session and comparing the data to the investigator’s manually measured reports.
Reference: John K. DeWitt, B.Sc.E., Paul J. Osterbauer. D.C., George E. Stelmach, Ed.D. & Arlan W. Fuhr. D.C.; Optoelectric Measurement of Leg Length Inequalities Before, During, and After Isolation Tests; Proceedings of the 1994 International Conference on Spinal Manipulation. Palm Spring, CA, June 10-11, 1994, p. 24-25.
Exercise and Sport Research Institute, Arizona State University Tempe, AZ 85287-0404 +Activator Methods. Inc. 3714 E. Indian School Road, Phoenix. AZ.
Changes in apparent leg length”(leg retraction) have been used by many as a means of locating subluxation in various Joints. The leg assessment is based on the assumption that unequal muscular contraction (e.g. hyper irritable muscles) about the spine and pelvis have the ability to retract one leg relative to the other. Despite Claims of usefulness, many problems are inherent in the prone leg assessment such as: a) measurement error; b) subject positioning by the examiner (expectancy bias) and; c) interference with die surface of the examining table. There have been prior attempts to quantify the amount of leg length changes that occur during a treatment session, but most have suffered due to the lack of a measurement technique which provides the necessary accuracy in the recording of slight changes in heel position. The purpose of this study was to quantify involuntary, movements that result from neck flexion and extension maneuvers. Five subjects exhibiting involuntary leg reactions were tested using an optoelectric motion analysis system. During each testing session, the subject lay prone on an adjusting table while infrared light emitting diodes (IREDs) were affixed to the heels of fracture boots. In the rest position, the neck was in neutral flexion so the face rested on the surface of the table. Prior to testing, the examination area was in neutral flexion so the face rested on the surface of the table. Prior to testing, the examination area was calibrated resulting in RMS errors of less than 0.3 mm. Data were collected for ten seconds by three cameras positioned to record movement of the IREDs. During each testing session, each subject preformed two movements; a head-up movement, during which the subject extended the neck and then returned to a resting position, and a chin-tuck movement, in which the subject flexed the neck and then returned to a resting position. A testing session consisted of three no-movement baseline trials, followed by three head-up trials and three chin-tuck trials. Examination of output displacement histories showed that during all trials, movement occurred at the heels in the direction of the subject’s longitudinal axis. During the head-up trials, a majority of cases showed a net shortening in heel position during head movement.
Reference: John K. Dewitt. B.Sc.E, Paul J. Osterbauer, D.C., George E. Stelmach, Ed.D., & Arlan W. Fuhr. D.C.; Optoelectric Measurement of Leg Length Changes During Isolation Tests; Proceedings of the CCR’s 8th Annual Conference on Chiropractic Science in Health Policy and Research, Monterey, CA, June 18-20, 1993, pp. 156-7.
Affiliation: Arizona State University, Phoenix. Arizona and National Institute for Chiropractic Research, Phoenix, AZ.
Changes in apparent leg length (LL) (leg retraction) have been used by many as a means of locating subluxation in various joints. The leg check is based on the assumption that unequal muscular contraction (e.g. hyper irritable muscles) about the spine and pelvis have the ability to retract one leg relative to the other. Despite claims of usefulness, many problems are inherent in the prone leg check such as: a) measurement error; b) subject positioning by the examiner (expectancy bias); c) interference with the surface of the examination table; d) possible overwhelming effects of large muscles over smaller intersegmental muscles and; e) lack of information of the validity of subluxation (eg. segmental aberration) and it’s supposed neurological effects. While observation of leg retraction has not yet been correlated with patient outcome or health measures, it is implied that the phenomenon apparent changes in LL occur due to altered tonic neck and back reflexes which coordinate spinal movements and posture. A video recording has been made of a patient who exhibited an unusually large amount of leg retraction which appeared to be due to asymmetrical contraction of their supra-pelvic musculature upon maneuvers such as tucking their chin.
The purpose of this study is to quantify the involuntary movements which nave been observed about the spine, pelvis and extremities using a 2D motion analysis system.
A subject exhibiting a large involuntary leg retraction will be sought. The patient will be positioned prone on an adjusting table. Retro reflective markers will be placed about their spine, pelvis and extremities. The markers will be recorded by two video cameras during maneuvers which cause the leg to retract.
This data will yield 2D maker locations which will be used to quantify the amount and type of movement.
Despite claims of utility of the prone leg check to locate subluxation and treatment success, many confounders occur. Lack of objective documentation and theoretical basis of the leg retraction phenomena has hindered its acceptance as an examination procedure. Only indirect evidence exists for its validity in several small observational studies where it was used to determine were to adjust. Motion analysis, and EMG studies may help in understanding the physiology of this phenomena using. Further work is necessary to correlate the relationship of leg retraction to other methods of subluxation assessment, treatment outcome and patient health status, if any.
Reference: Paul J. Osterbauer,DC; Arlan W. Fuhr,DC. Proceedings of the California Chiropractic Foundation’s 7th Annual Conference on Research and Education, June 19-21,1992; pp.291-292.