Facet joints are small, interlocking joints that connect each vertebra in your spine to the ones above and below it. There are two facet joints between every pair of vertebrae, one on each side, giving your spine both flexibility and stability. If you’ve heard the term from a doctor, it’s likely because one or more of these joints is causing back or neck pain, which is remarkably common as people age.
Where Facet Joints Are and How They’re Built
Each vertebra in your spine has bony projections that extend from its upper and lower edges. These projections overlap with those of the neighboring vertebra, and where they meet, they form a facet joint. Think of them as the hinges of your spine. They run in pairs down the entire length of your back, from your neck to your lower back, so you have dozens of them.
Facet joints are structured like other joints in your body, such as your knee or elbow. The bone surfaces inside the joint are covered with smooth cartilage so they can glide against each other without friction. The whole joint is enclosed in a fibrous capsule lined with a thin membrane that produces lubricating fluid. This capsule also contains tough ligament fibers that hold the joint together and resist excessive movement. Small folds of the joint lining sometimes extend into the joint space, improving how well the surfaces conform to each other during motion.
What Facet Joints Do
Facet joints serve two main purposes: they guide your spine’s movement and they help carry load. Every time you bend forward, lean back, twist, or tilt to the side, your facet joints are controlling and limiting that motion. They work in tandem with the discs between your vertebrae to allow movement while preventing anything that could injure the spine.
When you twist your torso, the facet surfaces compress together on one side and open on the other. This compression is what limits how far you can rotate and protects the intervertebral discs from excessive twisting forces. When you bend forward, the facet joints help maintain spinal stability by keeping the vertebrae from sliding too far forward on each other. In extension (leaning backward), the joint surfaces slide closer together and bear a larger share of the load.
Standing upright, your facet joints carry roughly 3 to 25% of the compressive load on your spine, depending on your posture and how much your discs have compressed over the course of the day. When you’re standing with a slight arch in your lower back, the load on the facet joints increases. When you’re sitting with a slight forward lean, the facets carry almost no load at all. This is one reason why certain postures feel better or worse when you have facet-related pain.
How Facet Joints Cause Pain
Facet joints are richly supplied with sensory nerves, which is why they can be a significant source of pain when something goes wrong. Each joint receives nerve branches from the spinal nerves at its level, meaning signals from an irritated facet joint can produce pain that feels local or that radiates into nearby areas.
In the neck, facet joint problems typically cause a dull, aching pain in the back of the neck that can spread to the shoulder or mid-back. Headaches and stiffness with limited range of motion are also common. In the lower back, facet pain tends to be felt on one or both sides of the spine and may radiate into the buttocks or upper thighs, though it rarely travels below the knee the way disc-related sciatica does.
The pain is usually worse with certain movements. Leaning backward, twisting, or standing for long periods tends to aggravate it because these positions load the facet joints. Sitting or bending forward often provides some relief, since those positions unload the joints.
Facet Joint Degeneration and Arthritis
Like any joint with cartilage, facet joints are vulnerable to wear and tear over time. The cartilage that allows smooth gliding gradually breaks down, letting bone contact bone directly. This triggers inflammation, thickening of the joint capsule, and eventually overgrowth of the bone itself, a process called facet hypertrophy. Bone spurs can form around the joint edges.
Facet joint arthritis is extremely common. Lumbar facet joints are responsible for chronic low back pain in roughly 15% of younger adults and 32% of older adults. Even among people without symptoms, imaging studies show facet joint arthritis at significant rates: about 45% of people have it at the L4-L5 level (lower back) and 38% at the L5-S1 level (the lowest mobile segment of the spine). When facet arthritis does cause symptoms, the L5-S1 level is affected most often, with over half of symptomatic cases occurring there.
The consequences go beyond pain. Your spinal canal, the bony tunnel that holds your spinal cord and nerve roots, has limited space. If a facet joint enlarges enough, it can narrow that canal and press on nearby nerves or the spinal cord itself. This is one of the ways spinal stenosis develops, and it can cause symptoms like leg pain, numbness, or weakness in addition to back pain.
Risk Factors for Facet Joint Problems
Age is the biggest risk factor. The cartilage in facet joints deteriorates with decades of use, and the degeneration tends to accelerate once disc height is lost, since shorter discs shift more load onto the facet joints. Previous injuries, particularly whiplash in the cervical spine, are another common trigger. Repetitive loading from certain occupations or sports, excess body weight, and poor posture all contribute to faster wear.
Disc degeneration and facet degeneration tend to reinforce each other. As a disc loses height, the vertebrae settle closer together, changing the alignment and load distribution of the facet joints. This accelerates cartilage breakdown in the facets, which in turn alters spinal mechanics further.
Diagnosis and Treatment
Facet joint pain can be tricky to diagnose because it overlaps with many other causes of back and neck pain. Imaging like MRI or CT scans can show structural changes such as joint enlargement, bone spurs, or fluid in the joint, but many people have these changes without any symptoms. The most reliable way to confirm that a facet joint is the source of pain is a diagnostic nerve block: a small amount of numbing medication is injected near the nerve supplying the suspected joint. If the pain temporarily disappears, the facet joint is likely the culprit.
Initial treatment is usually conservative. Physical therapy focused on core strengthening, flexibility, and posture correction can reduce the load on irritated facet joints. Anti-inflammatory medications help manage flare-ups. Adjusting daily habits, like avoiding prolonged standing or repetitive extension movements, can make a meaningful difference.
When conservative measures aren’t enough, a procedure called radiofrequency ablation targets the small nerves supplying the painful joint with heat, disrupting their ability to send pain signals. Results from prospective tracking of patients who underwent this procedure found that about 77% experienced at least 50% pain relief at one month, and that relief held at 79% out to two years. Average pain scores dropped from 6.6 out of 10 before treatment to 3.4 after. The nerves do eventually regenerate, so the procedure may need to be repeated, but it can provide a substantial window of relief.