The Effect of Manipulation and Chiropractic Adjustments

How Joints Misalign Or Lock Up

The function of a joint is to move two bones in relation to each other under muscular action. The muscles act, when they receive impulses, through nerves that arise in the spinal cord. The vertebral joints are like most other joints in that they move within defined limits according to muscle activity that is controlled by nerves leaving the spinal cord.

Very often injury, postural strains or other factors can irritate sensitive joint capsules that retain the lubricant that bathes the joint.A protective response is triggered that sends messages to muscles that control the joint, causing them to contract. The effect is to limit movement that might provoke more pain. This mechanism can also be triggered by injury or strain to other parts of the vertebral joint, such as its ligaments, disc, nerve, bone and even its own muscles.

So, any strain or injury to the joint or its associated structures may cause a muscle contraction that locks the joint either wholly or partially. That locking can occur with the joint in its neutral “aligned” position or, if muscles selectively contract, out of its neutral position, so the bones appear “out of alignment”. The mechanism serves a purpose whilst the injured tissue is healing by acting as nature’s own joint splint.

Anyone who cuts a finger knows how rapidly the tissues heal, become pliable again and return to full function. Unfortunately the spinal splinting mechanism can sometimes go wrong and perpetuate itself long beyond the time needed to repair the damaged tissue. The contracting muscle can be so over effective that it compresses its own blood supply, releasing acids that build up and trigger nerve endings into sensing pain, inducing a further protective spasm. A vicious cycle has been completed. In such an area one ligament might be held in stretch whilst that on the opposite side remains slack.

In time they will respond by lengthening and shortening respectively to balance the forces upon them, perpetuating the “misaligned” appearance. If a set of joints in a region locks up then its neighbours must compensate by increasing their own movement. As they increase their range they become less stable and themselves run the risk of strain or premature wear and tear, “osteoarthritis”. A whole region can slowly get stiffer and stiffer in the process so that bending the low back or reversing the car becomes a problem. The process can proceed unnoticed over months or even years until the over flexible area is injured and becomes painful.

What The Adjustment Does When the Chiropractor adjusts a joint he must first take up all the “slack” in the joint so as to control the movement perfectly. There the patient must contribute by relaxing completely to minimise any discomfort. The Chiropractor aims to induce a split-second stretch to the joint capsule and associated muscles and tissue fibres.

By taking up the slack the joint is opened as far as it can voluntarily go, a point referred to by Chiropractors as the “elastic barrier or resistance”. There is still ample room for the joint to move within its anatomical range, but if the movement is a slow stretch it triggers a natural resistance from the tissues of the joint. The speed of the Chiropractic adjustment is such that joint tissue resistance is not triggered and the elastic barrier is overcome, often producing a joint “crack”.

The main effect of the rapid stretch is a neurological response, which creates a wave of relaxation within the joint tissues, thereby restoring mobility. In cases where ligaments have physically shortened, the joint will tend to stiffen up again, although usually not to the same extent as before the adjustment. In time, with repeated adjustment at regular intervals, short ligaments will lengthen again, restoring full function to the joint.

It was once thought that the bones made the joint-crack as they “popped back into place”. Another theory was that the noise came from ligaments as they slapped tissues on being fully stretched. In the late Sixties researchers at Leeds University showed that the pop occurred within the fluids of the joint capsule. The sudden vacuum caused by stretching the joint brings gases out of the fluids in the form of tiny bubbles (anyone who saves wine from oxidation by using a bottle pump will notice how bubbles form in the wine if too much air is extracted). As the vacuum increases within the joint fluids, the bubbles come together until they form one sizable bubble. The next phase occurs as the bubble bursts with a “pop”. All this happens painlessly in a fraction of a split second.

Although it is an indication that a joint has been adjusted, the “crack” is not essential to the success of the adjustment, as it is the rapid stretch and not the bursting bubble that induces tissue relaxation and increased mobility. Indeed, Chiropractors have devised numerous methods over the years for restoring full mobility, not all of which require the mediation of the classic Chiropractic adjustment.

There are instances when the adjustment is not called for, as Daniel Palmer’s son, “B.J.”, recognised when he wrote: “It is more important to know when not to adjust than when to adjust”. In such cases Chiropractors will use some of their “non-force” techniques to restore movement and function to a faulty joint. Do not feel disappointed if your Chiropractor tells you your bone is not “out of place”. Excruciating pain can still be caused by locked joints, which are technically still in alignment. If you do not hear your joints go “crack” when they are treated do not feel cheated.

The quickest way to full function and painless relief may sometimes be a silent one.

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