Facet Joint Pain
Patients may experience back pain due to stresses exerted on the facet joints of the spine, or due to the arthritis of the smooth cartilage between the facets of the facet joints. Facet joints may degenerate on their own due to disease or time, and they may become worn out due to stressors we place on the spine when we exhibit bad posture (i.e. slouching, bending at the waist). The facet joints may also be affected by degenerative changes to other structures of the back, such as the spinal ligaments. Patients may experience pain or discomfort when these changes force the two facets of the facet joint together or apart. When the facets of the vertebral bones are pushed together, they may accelerate wear and tear of the smooth cartilage between them, and the facets may undergo changes when they come in contact with one another, causing irritation of the joint, or osteophytes in the facet faces of the bone.
Let's take a look at how the facet joint may become worn out, as a result of deterioration of the discs separating the spine. Think of the vertebral bones of the spine as building blocks, with one on top of the other to create the tower that is our human spine. Located between these building blocks are the intervertebral discs, which absorb pressures that are exerted on the spine as we sit up, stand, and walk. The ligaments of the spine provide additional support, holding the whole complex together, as well as the facet joints that provide additional support. The facet joints also protect the spine against excessive rotation, sideways, rotating, and bending back and forth.
The majority of the support of the spine is done by the discs and ligaments of the back. The facet joints, which provide linking of the vertebrae at the back of the spine, provide some support but may become vulnerable if the spine is consistently bent beyond healthy ranges, or if the intervertebral discs lose their original height due to disease or injury. When the disc shrinks or loses height, it can result in more pressure being exerted on the facet joints - the small joints at the back of each vertebrae which link it to the vertebrae above and the one below.
Imagine looking at the lower lumbar spine of a 20 year old healthy male, and then of the same spine 30 years later. In the earlier picture of the spine, the discs were plump and fully inflated, which enables the facet joints to maintain their alignment, with minimal pressure being exerted upon them. Fast forward 30 years, and you would see a disc that has become worn out, and lost more than 50% of its height, due to the loss of its ability to retain water. The loss of disc height brings the vertebrae closer together. The result is that the back of the vertebrae move closer together as well. Stretching of the ligaments of the spine, due to years of strain put upon them due to bad posture, may also destabilize the spine, and bring the facet joints closer together.
Forces exerted upon the facet joints, that bring them closer together, may cause facet joint arthritis and facet joint pain.