Snap, Crack, Pop! The Science of Spinal Manipulation Therapy

Neck and back pain are common ailments that in most episodes can resolve in two to six weeks, even without treatment. In some cases however, spine pain can lead to chronic pain, limited motion, and limited function. The economic burden associated with the management of neck pain in annual workers' compensation costs is second only to low back pain. One of the most common complementary health approaches used in treating this pain is known as spinal manipulation therapy (SMT).

Spinal manipulation is a technique performed by a practitioner such as physical therapists, chiropractors, osteopaths, and some medical doctors. The clinician uses their hands to apply a controlled, short and quick thrust to the spine. This results in multiple audible pops and cracks, known as a cavitation. Researchers have extensively searched for an answer as to what creates both the sound and benefits, but the exact mechanism remains unknown. Studies have hypothesized that SMT likely impacts sensory (afferent) neurons that transfer information to the brain about the surrounding tissues of the spine. This signal then alters the motor control and pain processing systems resulting in less pain, better neck motion, and improvements in the ability to perform daily activities. 

Considerable attention has been given to spinal manipulation for the potential risk of injury or stroke from these techniques. However, there is robust evidence to show no additional risk for vascular compromise, stroke, or worsening of disk herniations associated with manipulation. Conversely, the strong evidence to support spinal manipulation therapy for the treatment of low back pain, neck pain, and cervicogenic headaches has led to its inclusion in the Clinical Practice Guidelines by both the American Physical Therapy Association and the American College of Physicians. Spine manipulation therapy should, however, only be performed by a trained provider.