What Goes Wrong With My Back?

I propose that a simple back pain develops when an intervertebral disc (the fibrous pillow between the vertebrae) loses water content and stiffens. This can be caused by several factors, not least small-scale injury-either across or through the length of the spine-once the spine has become compressed. Then one of two things can happen for the problem to get worse: you can develop more serious trouble from the front compartment of the spine as the disc breaks down further. Or you can develop trouble from the back compartment as strain translates across to the facet joints. Worse still, you can get pain from both compartments at the same time. Finally, the whole sale destruction of both compartments can cause the vertebrae to jump around, in what is called segmental instability.The sequential disorder in the route of breakdown is as follows:

Stage 1: A STIFF SPINAL SEGMENT

An intervertebral disc between two vertebrae cases to be a buoyant pillow and becomes like a layer of compressed carpet. The vertebrae on top lose mobility and the segment becomes like a stiff link in the spinal chain. As it retires from activity the disc shrinks because it cannot generate sufficient suction to feed itself. Eventually, the flattening can be picked up on X-ray, but well before this point, the condition can be painful in what I believe is the most common spinal disorder.

Stage 2: ARTHRITIS OF THE FACET JOINTS

As a disc at the front of the spine drops in height it causes overriding of the bone-to-bone junctions (called the facet joints) at the back of the spine. The upper vertebrae settle down on the one below, causing bony rub between parts of the spine which could only have fleeting contact. Early on, this simply inflames the soft tissues around the facet joints but eventually, it causes arthritic change as it erodes the cartilage covering the bone. Facet joint trouble also is a relatively common form of low back pain.

Stage 3: AN ACUTE LOCKED BACK

This is a fluke incident when you are caught halfway through a movement by a pain like an electric cleaver going through your back. It makes moving in any direction excruciating and the body locks itself rigid. Although there never appears to be any warning, the problem usually has its origins in incipient disc breakdown.

All spines, even healthy ones, must brace themselves as they pass through a vulnerable part of the range at the beginning of a bending movement.If a disc between two vertebrae has flattened through the degenerative process, it may be unable to generate sufficient springing-apart tension to keep its segments stable as the spine goes over. 

The top vertebrae can jump imperceptibly out of joint at one of the facets, and the muscles develop instantaneous protective spasm to stop the vertebrae going any further. As a disc progressively loses its stuffing, it bulges like a perishing car tyre whenever it takes the weight. The fibrous disc wall takes most of the strain, and in some cases, it can perish at the points of greatest duress- usually one of the back corners. 

At the same time, the centre of the disc (called the nucleus) loses cohesion, after which excessive twisting and lifting activity can make it extrude through a fissure in the wall where it is weak. Sometimes the displaced nucleus lodges on a nearby spinal nerve and causes pain.