FORCES REQUIRED TO CAUSE CAVITATION DURING SPINAL MANIPULATION OF THETHORACIC SPINE

The purpose of this study was to measure the forces exerted during spi nal manipulative therapy of the thoracic spine simultaneously with cor responding cavitation signals. Forces were measured using a thin, flex ible pressure mat which was placed on patients over the contact area b etween doctor and patient. Cavitation signals were measured using a sk in mounted accelerometer on the spinous process of a vertebral body ad jacent to the manipulated vertebral body. Mean forces of spinal manipu lative therapy at the instant of cavitation were 364 N with a standard deviation of 106 N. These values are considerably larger than corresp onding values reported for cavitation at metacarpophalangeal joints. T he precise factors causing cavitation of the spinal joints could not b e determined. Study designs which may allow identification of these fa ctors are suggested.