Chiropractic manipulation

The term "adjustment" refers to the specific manipulation chiropractors apply  to vertebrae that have abnormal movement patterns or fail to function normally. The objective of the chiropractic treatment is to reduce the subluxation, which results in an increased range of motion, reduced nerve irritability and improved function.

The adjustment made by the chiropractor consists of a high velocity, short lever arm thrust applied to a vertebra, which is often accompanied by an audible release of gas (joint cavitation). The audible sound is caused by the release of oxygen, nitrogen, and carbon dioxide, which releases joint pressure (cavitation) (23). The sensation is usually relieving, though minor discomfort has been reported (that usually lasts for only a short time duration) if the surrounding muscles are in spasm or the patient tenses up during the chiropractic procedure.

There are times when joint cavitation or cracking does not occur and this is often due to either significant muscle splinting or the patient may not be adequately relaxed during the chiropractic procedure. At times like this, it is sometimes best for the chiropractor to apply ice, have the patient rest, or do electrical stimulationand massage prior to attempting spinal manipulation.

Positive effects of a chiropractic adjustment from a chiropractor
Objective effects of a chiropractic adjustment have been investigated and reported. More specifically, a single chiropractic adjustment produces both sensory and motor effects as well as sympathetic nervous system effects.

The sensory and motor effects of a chiropractic manipulation include:

• increased joint ROM in all 3 planes and reduction of pain (24, 25)
• increased skin pain tolerance level (26)
• increased paraspinal muscle pressure pain tolerance (27)
• reduced muscle electrical activity and tension (28)

Sympathetic nervous system effects of a chiropractic manipulation include:

• increased blood flow and distal skin temperature (fingertips) (29)
• blood pressure reduction (30, 31)

Blood chemistry changes after a chiropractic manipulation include:

• increased secretion of melatonin (32)
• increased plasma beta endorphin levels (33)
• elevation of Substance P and enhanced neutrophil respiratory burst (34)
• pupillary diameter changes (35).

There are many different techniques a chiropractor can choose from and there is a certain skill level and "art" involved with high velocity, low amplitude adjustment or manipulation. It is perhaps more important for the chiropractor to determine when not to apply the adjustment, which is the reason for the extensive academic load placed on the chiropractic student (4 years of college plus 4 years at a chiropractic college).

The number of chiropractic treatments required for the particular patient varies significantly due to the degree of the injury, the biovariability between patients, and co-morbid risk factors of chronicity (anxiety, depression, poor coping strategies, financial distress, low educational attainment, and others) (36, 37). For example, the chiropractic treatment plan of a grade 1, lumbar sprain/strain rarely demands greater than 4-6 weeks to manage in an uncomplicated case with no co-morbid factors.