Facets, or facet joints, are small paired joints that connect each vertebra in your spine to the one above and below it. They are the only synovial joints in the spine, meaning they have a fluid-filled capsule and smooth cartilage lining, much like your knee or hip. Every level of your spine has two facet joints, one on each side, and together they play a central role in how your back moves, how much it can twist, and how stable it stays under load. When facet joints break down, they account for an estimated 15% to 40% of chronic low back pain cases.
Where Facet Joints Are and How They’re Built
Each vertebra has bony projections that extend upward and downward from its back surface. The upward-facing projection of the lower vertebra meets the downward-facing projection of the vertebra above, forming a facet joint. This arrangement repeats at every spinal level from the neck down to the lower back, giving you dozens of facet joints in total.
Structurally, facet joints are lined with smooth cartilage, enclosed in a fibrous capsule, and filled with a small amount of joint fluid that reduces friction. This design is identical in principle to larger joints elsewhere in your body. Because of that similarity, facet joints are vulnerable to many of the same problems: arthritis, inflammation, injury, and infection.
What Facet Joints Do
Facet joints serve two main purposes. First, they guide and limit movement. When you bend forward, the joint surfaces slide upward relative to each other. When you lean back, they slide downward. This controlled sliding is what keeps your vertebrae from shifting too far in any direction. In the lower back, facet joints are especially important for limiting twisting. The joint surfaces compress together on one side during rotation, acting as a physical stop that protects the discs from excessive torsion.
Second, facet joints share some of the spine’s weight-bearing load. When you’re standing upright, roughly 16% of the compressive force on your spine passes through the facet joints. That number changes with posture. Sitting in a slightly forward-leaning position drops the facet load to nearly zero, while leaning backward or losing disc height (a common result of aging) pushes it higher, potentially up to 40% of the total force. This is one reason back pain from facet problems often feels worse with prolonged standing or arching backward.
Signs of Facet Joint Problems
Facet joint syndrome produces pain that is typically felt on one or both sides of the lower back, often radiating into the buttocks, the outer hip area, or the thighs. A defining feature is that the pain usually stops above the knee. It tends to be worst in the morning, during periods of inactivity, and after activities that involve leaning backward or twisting. Both standing and sitting for long stretches can provoke it.
This pain pattern can be confusing because it sometimes mimics a herniated disc. When bone spurs or small cysts develop around a facet joint, the radiating pain can extend all the way to the foot, closely resembling sciatica. The key difference is that true facet joint pain generally doesn’t cause numbness, tingling, or muscle weakness in the leg, which are hallmarks of nerve compression from a disc problem.
What Causes Facet Joints to Break Down
The most common cause is simple wear and tear over time. The cartilage lining the joint surfaces gradually thins with age, eventually allowing bone to contact bone. The body responds by growing extra bone around the joint, a process called facet hypertrophy, which enlarges and stiffens the joint. On imaging, a provider can grade this thickening as mild, moderate, or severe.
Several factors accelerate the process. Carrying excess body weight increases the compressive load on facet joints. Poor posture shifts more force onto them than they’re designed to handle. Previous spine injuries, even minor ones, can set the stage for earlier cartilage breakdown. Repetitive heavy lifting is another common contributor. Loss of disc height from a deteriorating disc also forces the facet joints to absorb a larger share of spinal loads, which speeds their degeneration further.
How Facet Pain Is Diagnosed
No single imaging scan can confirm that a facet joint is the source of your pain. Enlarged or arthritic-looking facet joints are extremely common on MRI and CT scans in people who have no symptoms at all. So while imaging can show physical changes in the joint, the gold standard for pinpointing facet pain is a diagnostic nerve block.
During this procedure, a small amount of numbing medication is injected near the tiny nerves that carry pain signals from the facet joint. If your pain drops significantly afterward, that confirms the facet joint as the source. Clinical guidelines call for these injections to be performed under imaging guidance (fluoroscopy or CT) to ensure accurate needle placement.
Treatment Options
Initial treatment for facet joint pain is typically conservative: physical therapy focused on core strength and flexibility, activity modifications to avoid aggravating postures, and over-the-counter anti-inflammatory medications. Many people improve with these steps alone, particularly if the problem is caught before significant joint damage has occurred.
When conservative measures aren’t enough, injections into the facet joint or around the nerves supplying it can provide relief. Studies show that roughly 25% to 39% of patients experience at least a 30% reduction in pain and disability scores within six weeks of these injections.
For longer-lasting relief, a procedure called radiofrequency ablation uses heat to interrupt the nerve signals carrying pain from the facet joint. In one large review, patients averaged about 48% pain improvement lasting roughly four to five months. Some studies report stronger results: one found that at 12 months, 87% of patients still had at least 60% pain relief. The nerves do regrow over time, so the procedure may need to be repeated, but it can offer meaningful stretches of reduced pain for people who respond well.
Facet Pain vs. Disc Pain
Because facet joint problems and disc problems both cause back pain that can radiate into the legs, telling them apart matters for choosing the right treatment. A few practical differences help distinguish them. Facet pain is usually provoked by leaning backward or twisting, while disc pain more often worsens with bending forward or sitting. Facet pain rarely travels below the knee and doesn’t cause true neurological symptoms like foot drop or patches of numbness. Disc-related pain, by contrast, frequently shoots down a specific path in the leg and may come with weakness or sensory changes.
That said, the overlap is real. Some patients have both facet and disc problems simultaneously, which makes diagnosis trickier. Diagnostic nerve blocks remain the most reliable way to sort out how much of someone’s pain is coming from the facet joints versus other structures.