Three-dimensionality of direct contact forces in chiropractic spinal manipulative therapy

Objective: To perform three-dimensional (3-D) manual contact force measurements of chiropractic adjustments at the patient-chiropractor interface. Methods: A new hand/palm-held computerized 3-D force measuring system was used to collect 3-D force data at the doctor-patient interface (direct measurement) during cervical, thoracic, and sacroiliac adjustments by 2 chiropractors on 10 healthy subjects. Results: 3-D components of force were significantly greater than matching 1-dimensional (1-D) perpendicular force components, which have been the standard in direct measurement up until now. As well, 3-D components of force were significantly different between adjustment levels, suggesting different dynamics (kinetics) of adjustment techniques. Force magnitudes and statistically significant differences between loading rates and adjustment levels fit in the existing body of knowledge of chiropractic adjustment forces. Conclusion: To our knowledge, this is the first study which presents 3-D force-time histories of chiropractic adjustments recorded at the doctor-subject interface. Direct 3-D contact force data seem to have the potential to contribute to chiropractic research because of a more complete description of this biomechanical aspect of daily practice. Results can be used to study novice and experienced chiropractors' techniques and permit the development of training and evaluation protocols in teaching institutions.