In the United States we have 19 different Chiropractic colleges. Each college has differing philosophies and teach different techniques. Currently we have about 200 different recognized Chiropractic techniques in the profession. The philosophies for the most part have overlap as the techniques also have some overlap. The big difference is on which end of the spectrum a Doctor chooses to follow. You may meet a Chiropractor who believes that a spinal subluxation is the cause of all human disease and on the other end of the spectrum you may meet a Chiropractor that does not even mention the word subluxation and believes they only treat diseases of the musculoskeletal system much like a Physical Therapist. The common ground among all Chiropractors is they believe that performing spinal manipulations has a profound effect on the nervous system which in turn affects other systems in the body. Chiropractors all believe that our bodies have an innate intelligence to heal itself when the nervous system functions optimally. So each Chiropractor has a philosophical belief on what affects a spinal manipulation has on the body and practices techniques they believe best accomplishes their goal.
The first established Chiropractic philosophy and technique started in the United States in 1895 by D.D. Palmer. He theorized that the vertebra would slightly dislocate and cause disharmony of nerve tone. This nerve tone was described by him as interruption in vibration of the nerves that allow nerves to communicate between the brain and all parts of the body. I wont run on about all of the twists and turns related to the original theory but modern theory has moved away from tone of the nerves to impingement of the nerves. This theory is the Subluxation Theory in chiropractic which is based on spinal misalignments or subluxations causing mechanical nerve impingements. These impingements can obviously result in pain throughout the body depending on location in the spine subluxations are located but they are also believed to effects organ function. A central part of this theory is a subluxation exists because either a dysfunctional organ or body part is sending overload of signals to the spine causing it to subluxate. Trauma can also cause a subluxation. It is believed that when the subluxation is corrected nerve interference is removed and the body part or organ returns to normal function. You know if you are working with a Chiropractor practicing this philosophy because they usually do X-rays to asses spinal alignment and only perform and adjustment during the treatment.
The second major Chiropractic philosophy and technique commonly referred to as Diversified does not use the word subluxation or talk about directly correcting spinal misalignment. This philosophy believes that the vertebra can become restricted and become an immobile segment. These restrictions will limit spinal mobility and result in stiffness in the spine but more importantly when joints are not moving properly it affects a larger system called proprioception. Proprioception is the system our body uses to give us awareness of location of our body in space. A good example is when you have your eyes closed you know where everybody part is and what angle your joints are bent at, we are aware by receptors in the skin, muscles, and joints feeding the brain information. Our spine and especially our neck have a large amount of proprioceptive receptors in the joints and muscles surrounding the spine. When these joints become locked they are no longer feeding information to the brain about position sense. This lack of information causes the central nervous system to fall back on primitive posture reflexes resulting in muscle imbalance in posture tone . This creates a muscle imbalance that over time leads to many different types of pain. A chiropractic manipulation is then performed to restore spinal motion and restore normal muscle balance. This theory places emphasis less on nerve impingement from misalignment to decreased input going to the brain as a result of restricted spinal joint motion. You know you are working with a Chiropractor practicing this philosophy because they spend more time testing muscle strength and flexibility before adjusting. Visits usually take longer because this method not only addresses the adjustment but also focuses on stretching and massage therapy to help correct muscle imbalances.
The original techniques were based off the teachings of D.D. Palmer who is pictured on the page. His theory dealt with subluxation impinging nerves and affecting nerve tension. Misalignments can tense or slack a nerve causing changes in vibrational frequency affecting communication of the brain with the body. While X-ray was not around in the early stage of Chiropractic the belief was that bones were out of place and needed to be popped in. D.D would feel the spine and make corrections based off how the boney alignment felt. Soon with development of X-rays his son B.J. Palmer introduced this new technology as an assessment tool. Palmer School of Chiropractic was the first school teaching the Palmer Methods overtime new schools opened across the country all following Subluxation philosophy but adapting different types of adjusting techniques. As new schools started opening and more Doctors were practicing new spinal adjusting techniques started being taught. New ideas brought the development of many techniques both for detecting subluxations and corrections of them. Commonly used Subluxation techniques include Palmer Upper Cervical, Gonstead, Thompson Drop, Applied Kinesiology, Activator, Logan Basic, Sacro-Occipital, Flexion Distraction, and Pierce-Stillwagon. The most common Diversified techniques are harder to place names on because it has its own philosophy so methods vary based on school teaching this method and many use manipulation techniques from the subluxation techniques. As an example I am considered a Diversified practitioner and I use a method called coupled adjusting technique which I believe is the optimal method to free restricted segments but I also use some parts of Sacro-Occipital Technique and on occasion I use the Activator Tool or Thompson Drop to deliver an adjustment. I believe every person is unique and some corrections would use to much force for a person or the opposite a person needs more force than normally used.
The short answer is all the above. If a Chiropractor is skilled at delivering a spinal adjustment to the area needed the body will heal naturally. The only difference is the skill of the practitioner and how well they can detect what is causing the problem and apply a proper spinal manipulation. I believe that adding stretching programs and massage therapy will speed the recovery time. I have been trained in the newer neurologic based theory and found great success practicing the techniques associated with this philosophy. I believe that results are the most important factor and if care is delivered correctly you do not need to see a Chiropractor 3 times per week for months on end. Results should be attained within a 4-6 visit time frame for the average patient. If it is taking longer than we are not dealing purely with restricted segments in spine or subluxations impinging nerves. In these cases we are usually dealing with herniated discs, chronic tendonitis/bursitis, or degenerative spinal stenosis. Chiropractors still have the ability to address these issues also but adjunct therapies such as decompression and other physical modalities are incorporated into manipulative care.