Facet arthrosis is the gradual wearing down of the small joints that connect each vertebra in your spine, much like the arthritis that develops in a knee or hip. These joints, called facet joints (or zygapophyseal joints), are lined with cartilage and enclosed in a capsule filled with lubricating fluid. When that cartilage degrades over time, bone can rub against bone, the joint becomes inflamed, and the result is stiffness and pain that can range from a dull ache to something that mimics sciatica. The condition is remarkably common, particularly as people age, and understanding how it develops and how it differs from other causes of back pain matters for getting the right treatment.
What the Facet Joints Actually Do
Your spine is not one solid column. Each pair of vertebrae connects at three points: the large disc in front and two facet joints in the back. These facet joints guide and limit how far you can bend, twist, and extend your spine. They are true synovial joints, meaning they have opposing cartilage surfaces that create a low-friction gliding environment, wrapped in a ligamentous capsule that holds everything together.1PubMed Central. Spinal facet joint biomechanics and mechanotransduction in normal, injury and degenerative conditions When you arch your back, the facet joints bear a larger share of the load; when you bend forward, most of the weight shifts to the disc.
Because these joints move with nearly every motion of the trunk and bear compressive forces every time you stand or walk, the cartilage inside them takes a beating over a lifetime. One study that examined 154 human facet joints from cadaveric specimens found that every single one showed some degree of cartilage degradation. In the worst cases, the cartilage had worn away entirely, leaving bare bone exposed.2Acta Biomaterialia. Characterization of facet joint cartilage properties in the human and interspecies comparisons That finding underscores how universal the process is. The question is rarely whether facet arthrosis will develop, but how far it will progress and whether it will become painful.
The Disc-Facet Feedback Loop
Facet arthrosis rarely happens in isolation. The intervertebral disc and the facet joints behind it function as a single mechanical unit, so when one starts failing, the other tends to follow. As a disc loses height from degeneration, the vertebrae settle closer together. That shifts extra compressive force onto the facet joints, particularly when the spine is extended. The tips of the inferior articular processes can press into the opposing joint surface, pinching the capsule and triggering pain.3Spine Surgery and Related Research. Biomechanics of the Lumbar Facet Joint
Finite element modeling studies confirm that the relationship goes both ways. Early disc degeneration has the biggest effect on facet loading. But as the facet joints themselves start to degenerate, they begin to influence how the disc is loaded, essentially accelerating the disc’s decline.4Journal of Biomechanics. Relationship between intervertebral disc and facet joint degeneration: A probabilistic finite element model study This feedback loop is one reason that back problems can seem to snowball. A disc that starts to narrow pushes extra stress onto the facets, and the facets, once arthritic, redistribute stress back onto the disc. By the time someone shows up with significant facet arthrosis, there is often disc degeneration at the same level.
Who Gets It and Why
Age is the dominant risk factor. In a large imaging study comparing normal and stenotic lumbar spines, the prevalence of facet arthrosis climbed steeply from the youngest adult cohort (ages 18 to 39) to the oldest (over 60). The same study found that facet arthrosis was independent of sex and body mass index, suggesting that the sheer passage of time and cumulative loading matter more than whether you are male or female, or how much you weigh on a standard BMI scale.5Spine. Facet Joints Arthrosis in Normal and Stenotic Lumbar Spines
That said, body composition may still play a role, even if overall BMI does not tell the full story. A separate study measuring outer abdominal fat found that this specific type of fat was significantly associated with facet joint arthritis, even when overall BMI and spinal alignment were not.6PubMed. Obesity measured by outer abdominal fat may cause facet joint arthritis at the lumbar spine In other words, where you carry your weight may matter more than how much you weigh in total. A large belly shifts your center of gravity forward, forcing the lumbar spine into more extension and loading the facet joints harder.
Physical activity and body stature factor in as well. A study using CT imaging found that older age, shorter height, and greater weight were all independently and significantly associated with severe lumbar facet osteoarthritis.7The Spine Journal. Physical activity and associations with computed tomography–detected lumbar zygapophyseal joint osteoarthritis The height connection likely reflects spinal biomechanics: shorter spinal segments may concentrate force on smaller facet surfaces.
What Facet Pain Feels Like
Facet arthrosis pain has a recognizable pattern, though it overlaps with other spinal conditions enough to make diagnosis tricky. The most common complaint is axial low back pain, meaning pain centered in the spine itself rather than shooting down the legs. In more advanced cases the pain can be on both sides.8PubMed. Pain originating from the lumbar facet joints It tends to be worse in the morning and after prolonged sitting or standing, and it flares with activities that extend or rotate the spine, like arching backward or twisting to look over your shoulder.
Facet pain can also radiate. From the lower lumbar levels (L4 and L5), it often spreads into the buttock and the side of the hip. From slightly higher levels, it can reach the groin and the front of the thighs. This referral pattern usually stops above the knee and does not come with neurological deficits like numbness or muscle weakness, which is what distinguishes it from a true pinched nerve. However, the mimicry is not always clean. In some cases, osteophytes (bone spurs) or synovial cysts that grow from a degenerating facet joint can press on nearby nerve roots and produce pain that travels all the way to the foot, closely resembling sciatica.9PubMed Central. Facet joint syndrome: from diagnosis to interventional management When that happens, teasing apart the contribution of the facet joint from a disc herniation becomes more difficult.
How Doctors Figure Out It Is the Facet Joint
No single test definitively proves that your pain is coming from a facet joint. Instead, diagnosis involves layering together clinical clues, imaging, and, when needed, diagnostic injections.
A doctor will suspect the facets based on your history and a physical exam. Tenderness when pressing over the facet joints, pain that worsens with spinal extension, and a referral pattern that stays above the knee all point in that direction. The differential diagnosis is broad, though: disc degeneration, spinal stenosis, herniated discs with radiculopathy, sacroiliac joint dysfunction, and inflammatory conditions can all produce overlapping symptoms.10PubMed. Lancinating lumbar facet syndrome: a congenitally absent facet joint
MRI can show facet arthrosis directly. It reveals joint space narrowing, bone spurs, fluid within the joint, and thickening of the capsule. Studies have found a positive correlation between higher grades of facet arthrosis on MRI and the severity of clinical symptoms.11INTERNATIONAL JOURNAL OF SCIENTIFIC RESEARCH. MODIC VERTEBRAL ENDPLATE MARROW CHANGES AND FACET JOINT ARTHROSIS ON MRI AND THEIR CORRELATION WITH CLINICAL SYMPTOMS In the cervical spine, bone marrow edema within a facet joint on MRI has been correlated with symptoms on the same side in roughly 73 to 83 percent of cases, depending on the spinal level examined.12Clinical Radiology. Cervical facet oedema: prevalence, correlation to symptoms, and follow-up imaging But imaging alone has a limitation: plenty of people with arthritic-looking facets on a scan have no pain at all, and some people with relatively normal-looking joints hurt considerably.
When the clinical picture is ambiguous, a medial branch block can serve as a diagnostic test. A small amount of local anesthetic is injected onto the tiny nerves that supply a specific facet joint. If your pain drops substantially for the expected duration of the anesthetic, the facet joint is very likely your pain generator. This technique has been validated extensively and accepted as reliable evidence of facet-mediated pain in clinical and legal settings across multiple countries.13PubMed Central. Medial Branch Blocks for Diagnosis of Facet Joint Pain Etiology and Use in Chronic Pain Litigation A positive block also opens the door to more targeted treatment.
Conservative Treatment and Steroid Injections
The first line of treatment is almost always conservative: physical therapy to strengthen the muscles that stabilize the spine, activity modification to reduce extension-heavy movements that load the facets, anti-inflammatory medications, and sometimes manual therapy. Many people improve enough with these measures that they never need anything more invasive.
When conservative care falls short, steroid injections into or around the facet joint are a common next step. The evidence for these, though, is more complicated than many patients expect. One landmark controlled trial injected either corticosteroid or saline placebo directly into the facet joints of patients with chronic low back pain. At one month and three months, there was no meaningful difference in pain, function, or back flexibility between the two groups. About 42 percent of the steroid group reported marked improvement, compared with 33 percent of the placebo group, a gap that was not statistically significant.14PubMed. A controlled trial of corticosteroid injections into facet joints for chronic low back pain By six months the steroid group looked somewhat better, but when the researchers accounted for other treatments the patients had pursued in the meantime, the difference shrank.
Broader reviews have reached a similar verdict: intra-articular steroid injections for facet pain produce generally disappointing results on average, though a subgroup of patients with active inflammation appear to get intermediate-term benefit.15Nature Reviews Rheumatology. Facet joint pain—advances in patient selection and treatment The takeaway is not that steroid injections never help, but that they are unreliable as a standalone solution and work best when there is genuine acute inflammation rather than longstanding mechanical wear.
Radiofrequency Ablation
For patients whose pain has been confirmed by medial branch blocks but who do not get lasting relief from injections, radiofrequency ablation (RFA) offers a more durable option. The procedure uses heat delivered through a needle to disable the tiny medial branch nerves that transmit pain signals from the facet joint. The joint itself is not repaired. Instead, the pain pathway is interrupted.
Long-term follow-up data are encouraging. In one study with a median follow-up of about three years after RFA, roughly 58 percent of patients reported at least a 50-percent improvement in function, and about 53 percent reported at least 50-percent improvement in pain. About a third experienced 75 percent or greater pain reduction, and around one in five said their function was completely restored.16PubMed Central. Long-Term Function, Pain and Medication Use Outcomes of Radiofrequency Ablation for Lumbar Facet Syndrome These are not cure rates, but for a condition rooted in irreversible cartilage loss, cutting pain in half for years is a significant win.
Technique and temperature matter. A comparison of needle-placement methods found that a more advanced placement technique yielded a median duration of pain relief of four months, compared with just one and a half months with a standard approach.17PubMed Central. Efficacy of needle-placement technique in radiofrequency ablation for treatment of lumbar facet arthropathy And a randomized trial comparing ablation at 80°C versus 90°C found that the higher temperature nearly doubled the median time before patients needed a repeat procedure, going from about 112 days to about 217 days. Patients treated at 90°C were also roughly 2.7 times more likely to achieve a 50-percent or greater pain reduction.18PubMed. Impact of temperature on the magnitude and duration of relief after lumbar facets medial branch nerves radiofrequency ablation: a randomized double-blinded study The nerves do eventually regenerate, which is why repeat ablations are common, but the procedure can be performed again with similar effectiveness.
When Facet Arthrosis Contributes to Spinal Stenosis
Left unchecked, facet arthrosis does not stay confined to the joint. As the facet joints enlarge with bone spurs and the capsule thickens, they can encroach on the spinal canal and the openings where nerve roots exit. This is one of the classic contributors to lumbar spinal stenosis in older adults, alongside disc bulging and thickening of a ligament called the ligamentum flavum.19PubMed Central. Lumbar spinal stenosis in the elderly: an overview Stenosis symptoms typically include leg pain, heaviness, or numbness that worsens with walking and improves with sitting or bending forward, a pattern called neurogenic claudication.
At this stage, the facet joint is no longer just a pain source. It is a structural problem that may be compressing neural tissue. This is the point at which surgery enters the conversation.
Surgery for Advanced Cases
Most people with facet arthrosis never need an operation. But when arthritic facet joints contribute to stenosis or instability that does not respond to conservative or interventional care, surgical decompression can help. A randomized controlled trial showed decompression surgery was superior to non-surgical management for lumbar spinal stenosis, with a clinically meaningful improvement in disability scores.20PubMed Central. The Diagnosis and Treatment of Degenerative Changes of the Lumbar Spine
The more contentious question is whether to add spinal fusion to the decompression. Fusion locks two or more vertebrae together, eliminating motion at the arthritic segment. But pooled data on fusion procedures have not shown a statistically significant advantage over decompression alone for stenosis patients.20PubMed Central. The Diagnosis and Treatment of Degenerative Changes of the Lumbar Spine Reviews of surgical practice suggest that 90 to 95 percent of stenosis cases can be managed with decompression alone, and fusion should be reserved for the small minority who have clear instability before surgery or who develop slippage after a laminectomy that removes too much of the facet.21Neurosurgical Focus. Surgical management of lumbar stenosis: decompression and indications for fusion
A recent study specifically examined patients with high-signal (inflamed) facet joints on MRI and found that both decompression alone and decompression with fusion produced significant improvements in pain and disability. The researchers concluded that fusion may not be necessary in these patients unless there are additional markers of instability.22PubMed. Comparable long-term pain and disability outcomes following decompression alone versus decompression with fusion in lumbar spinal stenosis patients with high-signal facet joints If you are told you need fusion specifically because of facet arthrosis, it is worth asking whether decompression alone might achieve the same outcome.
Platelet-Rich Plasma and What Is Coming Next
One of the more promising directions in facet joint treatment is the use of platelet-rich plasma (PRP), which concentrates growth factors from your own blood and injects them into the joint. The idea is to promote some degree of tissue repair and reduce inflammation, rather than simply masking the pain.
Early prospective data are encouraging. One study compared CT-guided PRP injections with local anesthetic injections for facet joint syndrome. Both groups improved in the first two weeks, but from six weeks onward, the PRP group showed significantly better pain scores than the anesthetic group, and the benefit persisted up to one year. Disability scores improved to roughly half their baseline values in the PRP group and remained significantly better at 12 months.23PubMed Central. Platelet Rich Plasma for the Therapy of the Lumbar Facet Joint Syndrome: A Prospective Study About CT-Guided Facet Joint Injections With PRP Compared to Local Anesthetics A separate study comparing PRP with corticosteroid-plus-anesthetic injections found that while the steroid group’s satisfaction and success rates peaked at one month (80 percent satisfaction, 85 percent objective success) and dropped to 50 and 20 percent by six months, PRP maintained better outcomes across the follow-up period.24PubMed. A Prospective Study Comparing Platelet-Rich Plasma and Local Anesthetic (LA)/Corticosteroid in Intra-Articular Injection for the Treatment of Lumbar Facet Joint Syndrome
PRP is not yet a standard treatment for facet arthrosis. The studies so far are relatively small, protocols vary in how the plasma is prepared and injected, and insurance coverage is spotty to nonexistent in most countries. But the trajectory of the evidence is enough that some pain clinics now offer it as an option for patients who respond to diagnostic blocks but want something beyond repeated steroids or ablation. Whether PRP can actually slow cartilage loss in the facet joint, rather than just reducing pain and inflammation, remains an open question that larger trials will need to answer.
Why Upright Walking Makes the Facets Vulnerable
There is an evolutionary backdrop to all of this. In a typical upright standing posture, roughly 16 percent of the spine’s total compressive load passes through the facet joints. But even slight extension of the lower back redirects another 12 percent onto the facets, and during pregnancy, when the lumbar curve increases by an average of about 18 degrees, published biomechanical models estimate that 20 to 40 percent of the spinal load may shift to these joints.25Nature. Fetal load and the evolution of lumbar lordosis in bipedal hominins The facet joints were originally designed for quadrupedal spines, where loads distribute very differently. Walking upright was an extraordinary evolutionary innovation, but it came with trade-offs. The facet joints are one of the structures paying the price, bearing loads they were not originally shaped to handle over 70 or 80 years of bipedal life. That context helps explain why facet arthrosis is so nearly universal in aging humans and why no amount of perfect posture or exercise fully prevents it.