Measurement and Analysis of Biomechanical Outcomes of Chiropractic Adjustment Performance in Chiropractic Education and Practice.

OBJECTIVE: The purpose of this study was to compare biomechanical measures of chiropractic adjustment performance of the McTimoney toggle-torque-recoil (MTTR) technique among students and chiropractors. METHODS: Fifty-three participants (15 year-3 [Y3] and 16 year-5 chiropractic students and 22 McTimoney chiropractors [DCs]) participated in this study. Each applied 10 MTTR thrusts to a dynamic load cell, 5 each with their left and right hands. Biomechanical variables including preload force, peak force, time to peak force, thrust duration, and total thrust time were computed from each of the force-time histories and compared within groups using a series of 2-way analysis of variance to evaluate the effects of sex and handedness, and between groups to determine the effect of experience using a series of 3-way analysis of variance. The Games-Howell post hoc test was used to further assess pairwise comparisons. RESULTS: Mean time to peak force was more than 3 × shorter for DCs (69.96 ms) compared with Y3 students (230.36 ms) (P = .030). Likewise, mean thrust duration was also found to be nearly 2.5-fold significantly shorter for DCs (117.77 ms) compared with Y3 students (283.84 ms) (P = .030). The DCs took significantly less total thrust time (mean = 1.27 seconds) in administering MTTR thrusts than Y3 students (1.89 seconds) (P = .006). No significant differences were found among any of the 3 clinician groups for peak force or in time to peak force or thrust duration for comparisons of all 10 MTTR thrusts among year-5 students and DCs. Higher peak forces were observed for thrusts delivered with clinicians' dominant hands (P = .001), and the fastest thrusts were found for the dominant hands of DCs (P = .001). Sex had no significant effect on biomechanical variables. The Y3 students had significant greater variability in thrust times for each hand and for analyses of both hands combined (P = .001). CONCLUSION: Training and experience were found to result in shorter MTTR thrust times and other biomechanical variables that have been identified as important factors in the mechanisms of chiropractic adjustments. Identification of such biomechanical markers as performance outcomes may be of assistance in providing feedback for training in chiropractic education and technique application.

Force-time profile characterization of the McTimoney toggle-torque-recoil technique.

OBJECTIVES: The purpose of this study was to characterize the force-time profile of the McTimoney toggle-torque-recoil (MTTR) technique. METHODS: Two licensed chiropractors trained in the McTimoney Method applied MTTR thrusts to a tabletop where a dynamic load cell had been mounted. Each clinician applied 10 thrusts (5 with each hand) to the load cell in a repeated measures design. Peak forces, time durations, and time to peak force were computed from each of the force-time histories. Descriptive statistics were performed to compare the forces, durations, and times to peak force of the MTTR thrusts. A Mann-Whitney U test compared variables between the 2 clinicians, whereas a Wilcoxon signed-rank test compared right- and left-handed thrusts within clinicians. RESULTS: Considering all MTTR thrusts, the average peak force was 87.22 N (SD = 24.18 N), the average overall thrust duration was 36.38 milliseconds (SD = 9.58 milliseconds), and the average time to peak force was 12.31 milliseconds (S.D. = 4.39 milliseconds). No significant differences in mean peak force, duration, or time to peak force were observed between clinicians. When comparing intraclinician right and left hand thrusts, differences in peak force and duration were observed individually (P < .05). CONCLUSION: For the 2 chiropractors tested, MTTR thrusts were relatively lower in peak force and appreciably faster than other commonly used chiropractic techniques. Future work aims to investigate the relationships between the force-time profiles of MTTR thrusts and resultant physiologic and clinical responses.

The biomechanical and clinical significance of the lumbar erector spinae flexion-relaxation phenomenon: a review of literature.

OBJECTIVES: The aim of this study was to review the biomedical literature to ascertain the biomechanical and clinical significance of the lumbar erector spinae flexion-relaxation phenomenon (FRP). DATA SOURCES: Index Medicus via PubMed, the Noble Science Library's e-journal archives, and the Manual Alternative and Natural Therapy Index System databases were searched using the same search terms. DISCUSSION: The presence of the FRP during trunk flexion represents myoelectric silence consistent with increased load sharing of the posterior discoligamentous passive structures. Passive contributions from erector spinae stretching during the flexion posture and active contributions from other muscles (quadratus lumborum and deep erector spinae among others) further assist in load sharing in the trunk flexion posture. A number of studies have shown differences in the FRP between patients with chronic low back pain and healthy individuals, and the reliability of the assessment. Persistent activation of the lumbar erector spinae musculature among patients with back pain may represent the body's attempt to stabilize injured or diseased spinal structures via reflexogenic ligamentomuscular activation thereby protecting them from further injury and avoiding pain. CONCLUSIONS: The myoelectric silencing of the erector spinae muscles in the trunk flexion posture is indicative of increased load sharing on passive structures, which tissues have been found to fail under excessive loading conditions and shown to be a source of low back pain. The studies that show differences in the presence of the FRP among patients and control subjects are encouraging for this type of clinical assessment and suggest that assessment of the FRP is a valuable objective clinical tool to aid in the diagnosis and treatment of patients with low back pain.

Manipulative treatment of carpal tunnel syndrome: biomechanical and osteopathic intervention to increase the length of the transverse carpal ligament: part 2. Effect of sex differences and manipulative "priming".

As a theoretical basis for treatment of carpal tunnel syndrome (CTS) and expanding upon part 1 of this study, the authors investigated the effects of static loading (weights) and dynamic loading (osteopathic manipulation [OM]) on 20 cadaver limbs (10 male, 10 female). This larger study group allowed for comparative analysis of results by sex and reversal of sequencing for testing protocols. In static loading, 10-newton loads were applied to metal pins inserted into carpal bones. In dynamic loading, the OM maneuvers used were those currently used in clinical settings to treat patients with CTS. Transverse carpal ligament (TCL) response was observed by measuring changes in the width of the transverse carpal arch (TCA) with three-dimensional video analysis and precision calipers. Results demonstrated maximal TCL elongation of 13% (3.7 mm) with a residual elongation after recovery of 9% (2.6 mm) from weight loads in the female cadaver limbs, compared to less than 1 mm as noted in part 1, which used lower weight loads and combined results from both sexes. Favorable responses to all interventions were more significant among female cadaver limbs. Higher weight loads also caused more linear translatory motion through the metal pins, resulting in TCA widening equal to 63% of the increases occurring at skin level, compared to only 38% with lower loads. When OM was performed first, it led to greater widening of the TCA and lengthening of the TCL during the weight loading that followed. Both methods hold promise to favorably impact the course of management of CTS, particularly in women.