Facet joint hypertrophy, or simply facet hypertrophy, refers to the enlargement of the facet joint. The facet joints, or zygapophyseal joints (Z-joints), are the connections of the posterior portion of adjacent spinal vertebrae. Between these joints are nerve roots that originate from the spinal cord and extend to the periphery of the body. When these joints enlarge due to injury or arthritis, the affected person experiences pain, decreased range of motion, and sometimes peripheral neuropathies. Treatment of this condition involves anesthetic or anti-inflammatory injection in the joint, exercise, physical therapy, and spinal braces.
The facet joints are cartilaginous hinges that help hold adjacent vertebrae together. They are synovial joints surrounded by capsules of lubricating fluid. Their main functions are to facilitate the range of movement of the spine. They also allow the passage of nerves from the spinal cord to the arms, legs, and other body parts. With aging, these facet joints may become enlarged.
Causes of facet joint enlargement are multifactorial. Rheumatoid arthritis (RA) may lead to the inflammation and thickening of the synovial lining of the joints. Osteoarthritis (OA) may cause the cartilage lining of the facets to wear away, leading to compensatory bone growth called bone spurs. With either inflammation or bone spurs, the facet joints hypertrophy or enlarge, leading to various symptoms.
The most common symptoms are facet joint pain, stiffness, and decreased range of motion. Additionally, the associated spinal nerves may become compressed due to facet hypertrophy. When this happens, referred symptoms can occur. For instance, even if the hypertrophy is located in the lumbosacral area or lower back, pain and numbness may be experienced in the legs and buttocks.
To diagnose facet hypertrophy, various imaging studies may be performed. A computed tomography (CT) scan or magnetic resonance imaging (MRI) may be done to look for facet degeneration, and a bone scan may be requested to detect inflammation. To confirm the diagnosis of facet hypertrophy or facet pain syndrome, a trial of anesthetic or anti-inflammatory injection is administered. When pain relief is experienced after injection, the diagnosis of this condition is confirmed.
The main mode of treatment for facet hypertrophy is the injection of steroids into the affected facet level. Other treatment options include oral anti-inflammatory drugs such as ibuprofen and naproxen, physical therapy, appropriate exercise, and spine braces. For severe cases and for people who want long-term relief, a surgical procedure called rhizotomy may be performed, which involves cutting the nerve roots to relieve the pain and numbness. Other surgical procedures include open-spine facet joint surgery, spinal fusion, and laminectomy. Surgical procedures, however, are invasive, and require general anesthesia and an extended hospital stay.