1. Traumatic degeneration of the facet joints. The primary insult may be motor vehicle accident, fall from height, etc
2. Age related degeneration of the joints or the mechanical degeneration of the joints. Anyone who lives long enough will definitely have some degenerative changes in the spine. But sometimes it becomes painful needing attention
3. Occupational hazards – Labourers may face this because of years of carrying heavy weights on their head and shoulders

Facet joint degeneration can be painless until an event triggers symptoms. There are several symptoms that indicate a person’s pain is coming from the facet joints. The pain is often a diffuse, dull ache in the low back directly over the spine that can spread to the buttocks. In the neck it can be felt in the shoulders and back of the skull.
Acute episodes of lumbar and cervical facet joint pain are typically intermittent, generally unpredictable, and occur a few times per month or per year.
Most patients will have a persisting point tenderness overlying the inflamed facet joints and some degree of loss in the spinal muscle flexibility (called guarding).
Typically, there will be more discomfort while leaning backward than while leaning forward.
Low back pain from the facet joints often radiates down into the buttocks and down the back of the upper leg. The pain is rarely present in the front of the leg, or rarely radiates below the knee or into the foot, as pain from a disc herniation often does.
Similarly, cervical facet joint problems may radiate pain locally or into the shoulders or upper back, and rarely radiate in the front or down an arm or into the fingers as a herniated disc might.

Imaging Modalities like X rays especially oblique views , CT and MRI can not only point towards the diagnosis of facet joint disease but it also helps in excluding other causes and other red flag signs of the spine

The most reliable test is an injection of local anaesthetic into the joint or into the nerves supplying the joint. If this does not relieve the pain it is unlikely that the pain is coming from the facet joints.

Conservative:-

NSAIDs have been used to help during flareups of pain. Other supportive measures like rest, spine strengthening exercises, hydrotherapy and traction can be tried. Osteopathic and Chiropractic manipulations have also seen to help some people to a great extent

Interventional-

When these measures do not provide adequate relief, interventional pain management comes into play. Mixture of LA and steroid have been injected around the nerves supplying the joint (well known as medial branch block) or directly into the joint itself. While blocking the nerves usually two- three levels are addressed at once owing to the peculiar nerve supply of these joints.These serve to be diagnostic as well as therapeutic. Blocking the nerves is preferred nowadays to injecting into the joint.

Regenerative Medicine-

Some centres are using Prp and stem cells into the facet joint to prvent the progression of arthritis but the efficacy of these procedures has yet to be proven in large scale studies.
Patients in whom the pain comes back after successful injections can be considered for radiofrequency ablation or rhizotomy of the medial branches supplying the facet joint

Facetectomy and foraminotomy to increase the the dimension of the intervertebral foramen and achieve adequate decompression of the affected nerve root when required
Finally fusion surgery of two or more vertebrae is carried out to eliminate movement at the affected level hence eliminating the pain producing movement.

Eliminating the cause , for instance a manual labourer with early symptoms may need to have amended duties to prevent the progression
Excercises to strengthen the spine and increase the mobility . People should be encouraged to take up some physical activity like yoga, pilates, aerobics or athletics whichever suits them.
Watch your weight.