Instrument adjusting is used as an alternative to manual manipulation of the spine or extremity joints. The device is categorized as a mechanical force manual assisted (MFMA) instrument which is generally regarded as a softer chiropractic treatment technique. A small handheld spring-loaded instrument which delivers a small impulse to the spine is found to give off no more than 0.3 J of kinetic energy in a 3-millisecond pulse. The aim is to produce enough force to move the vertebrae but not enough to cause injury.
This involves having the patient lie in a prone position and comparing the functional leg lengths. Often one leg will seem to be shorter than the other. The chiropractor then carries out a series of muscle tests such as having the patient move their arms in a certain position in order to activate the muscles attached to specific vertebrae. If the leg lengths are not the same, that is taken as a sign that the problem is located at that vertebra. The chiropractor treats problems found in this way moving progressively along the spine