Physician-applied contact pressure and table force response during unilateral thoracic manipulation.

OBJECTIVE: To measure the applied loading to human subjects during the reinforced unilateral thoracic manipulation. DESIGN: Biomechanical descriptive study. SETTING: The National College of Chiropractic Clinical Biomechanical Laboratory in Lombard, Illinois. SUBJECTS: Seven men, ages 24 to 47, with no positive responses regarding muscle relaxants or thoracic spinal fractures, surgeries, or pain. MAIN OUTCOME MEASURES: We measured the contact pressure distribution at the physician-subject contact region and extracted three biomechanical parameters. From the measured time-dependent support force magnitudes, we extracted five additional biomechanical parameters. RESULTS: In the application of the reinforced unilateral manipulative treatment, the physician establishes contact and applies a near-static preload force of 250 to 350 N. The dynamic portion of the typical thrust is preceded by a 22% decrease in force magnitude, and the peak thrust magnitude is linearly related to the preload force magnitude. We estimate that the peak contact pressure beneath the chiropractor's pisiform can exceed 1000 kPa, with the highest pressures transmitted over areas as small as 3.6 cm2, depending on manipulative style. CONCLUSIONS: This work represents the first attempt at performing simultaneous measurements of the physician-applied loading and table force response and measuring the contact pressure distribution at the physician-patient contact region during chiropractic manipulation. This type of work will lead to a better understanding of the relationship between the dynamic physician-applied normal forces and the resulting load response at the table and gives us additional outcome parameters to quantify manipulative technique.

Basic science research in chiropractic: the state of the art and recommendations for a research agenda.

A position paper was prepared as background information for participants in the National Workshop to Develop the Chiropractic Workshop Agenda conducted by the Palmer Center for Chiropractic Research, Davenport, Iowa. The paper was revised in light of comments and suggestions at the workshop by participants and by a workgroup composed of basic scientists from within and outside of chiropractic. This final article documents the history of basic science research in chiropractic, and the current state of the art of basic science research conducted since 1975 by chiropractors or investigators at chiropractic institutions in North America. Seed recommendations contained in the working paper for the development of an adequate infrastructure needed to conduct future research and seed recommendations for a future basic science research agenda were also modified and revised by the workgroup participants through a modified nominal group process. The final recommendations contained in this article represent a synthesis of these recommendations and those of the authors.

6R instrumented spatial linkages for anatomical joint motion measurement--Part 2: Calibration.

The six-revolute-joint instrumented spatial linkage (6R ISL) is often the measurement system of choice for monitoring motion of anatomical joints. However, due to tolerances of the linkage parameters, the system may not be as accurate as desired. A calibration algorithm and associated calibration device have been developed to refine the initial measurements of the ISL's mechanical and electrical parameters so that the measurement of six-degree-of-freedom motion will be most accurate within the workspace of the anatomical joint. The algorithm adjusts the magnitudes of selected linkage parameters to reduce the squared differences between the six known and calculated anatomical position parameters at all the calibration positions. Weighting is permitted so as to obtain a linkage parameter set that is specialized for measuring certain anatomical position parameters. Output of the algorithm includes estimates of the measuring system accuracy. For a particular knee-motion-measuring ISL and calibration device, several interdependent design parameter relationships have been identified. These interdependent relationships are due to the configuration of the ISL and calibration device, the number of calibration positions, and the limited resolution of the devices that monitor the position of the linkage joints. It is shown that if interdependence is not eliminated, then the resulting ISL parameter set will not be accurate in measuring motion outside of the calibration positions, even though these positions are within the ISL workspace.

6R instrumented spatial linkages for anatomical joint motion measurement--Part 1: Design.

Six-revolute-joint instrumented spatial linkages (6R ISLs) have become often-used devices to measure the complete six-degree-of-freedom motion of anatomical joints. Accuracy of motion measurement depends on ISL design and calibration technique. In this paper, a design process is outlined that uses computer graphics and numerical methods as aids in developing 6R ISLs that (i) physically assemble within the desired range of motion of the joint; (ii) do not collide with either the experimental apparatus or the subject joint; (iii) avoid singular linkage configurations that can cause forces to be applied to the joint; and (iv) measure selected anatomical motions most accurately. It is found that a certain subgroup of 6R linkages are suitable for accurate measurement of specific motions, and can be the basis for new ISL designs. General guidelines are developed that can assist in the generation of unique linkage designs for different anatomical joints. The design process is demonstrated in the creation of an ISL to measure knee motion.