Biomechanical Measure Validation for Spinal Manipulation in Clinical Settings

Objective: To evaluate the validity and fidelity of the Leander 900 Z Series treatment table (Leader Health Technologies Corporation, Port Orchard, Wash) with an imbedded AMTI force plate (Advanced Mechanical Technology, Inc, Watertown, Mass) as a sensing system and to test its ability to quantify small, statistically significant changes in biomechanical parameters of spinal manipulative therapy (SMT).

Setting: Technology bench testing and Chiropractic College.

Methods: Complex forces and moments were applied to the modified treatment table, including standardized static and dynamic loads and those exerted by chiropractic students when delivering spinal manipulative therapy. Manipulation data was postprocessed by a second-order Butterworth filter with a 5-Hz cutoff frequency. Changes in lumbar spinal manipulative therapy procedures performed by chiropractic students were digitally recorded using the sensing system at approximately 1-month intervals throughout the course of a trimester of training.

Results: The system frequency response remains relatively consistent over the interval of test loads from 89 N to 222 N and from 53 nm to 133 nm with fundamental frequencies 5.9 Hz and higher. Changes in biomechanical parameters, including peak amplitude, slope, and duration over time and training, were observed in student chiropractic manipulations. Results show a minimum of 18% (P =.0723) increase during interval 1 in mean peak amplitude and slope parameters. Only a slight (3%) mean reduction of the procedure duration was seen.

Conclusions: The results support the fidelity of the sensing system and its ability to quantify small, statistically significant changes in biomechanical parameters. With this type of instrumentation, it is feasible to assess the skill of chiropractic physicians performing spinal manipulative therapy.