Thrust Magnitudes, Rates, and 3-Dimensional Directions Delivered in Simulated Lumbar Spine High-Velocity, Low-Amplitude Manipulation

Objectives The purpose of this study was to measure faculty performance of simulated spinal manipulation on a mannequin to help identify teaching standards. Methods We measured 3-dimensional transmitted loads using a force plate mounted in the table. Thrusts were delivered through a compliant, jointed mannequin by faculty members along predefined “listings” as taught in lumbopelvic technique courses. Results Eleven chiropractic faculty members participated, delivering 9 thrusts at 3 loads (light, moderate, and heavy) along 9 different prone and side-posture listings, totaling 81 thrusts per participant. Single-hand Gonstead-style thrusts had variability in magnitude across participants and loads: light thrusts averaged 365 N (95% confidence interval [CI] 327-402), moderate thrusts 454 N (421-487), and heavy thrusts 682 N (623-740). All faculty members could easily distinguish the loads within their performances, but there was some crossover of load levels between participants. Thrust rates averaged 3.55 N/ms (95% CI 3.29-3.82). The dominant vector of prone thrusts was in the z direction (vertically downward), but side-to-side and inferior-to-superior vector components occurred. Conclusion Faculty member performance of simulated spinal manipulation indicated that they are able to control the thrust magnitude and rate as well as direction. In this sample, there was significant variability in peak loads between participants, which needs to be considered in student learning standards. These findings may be useful in translating the understanding of force characteristics to the technique teaching lab.