Degenerative facet disease, also termed facet joint osteoarthritis or facet arthropathy, is a common source of chronic back pain resulting from the slow breakdown of the spinal joints. This condition affects the small, paired joints located at the back of the spine, which are subject to the same wear-and-tear process seen in other joints. As a progressive disorder, it represents a natural consequence of aging and mechanical stress on the vertebral column. Understanding the mechanism of this degeneration offers a clearer path toward effective diagnosis and management. This overview will detail the function of these joints, the process of their decay, diagnosis, and treatment options.
Understanding the Facet Joints and Degeneration
The facet joints, also known as zygapophyseal joints, are small, synovial joints situated on the posterior side of the spine, where two adjacent vertebrae connect. These joints are lined with cartilage and surrounded by a fluid-filled capsule. They function to guide and limit the spine’s movement, preventing excessive rotation and forward slippage. They form a three-joint complex with the intervertebral disc, creating a stable yet flexible motion segment throughout the spine.
The degenerative process begins when the articular cartilage covering the joint surfaces starts to fray and wear thin due to mechanical stress. When the supporting intervertebral disc loses height, the mechanical load on the facet joints increases, accelerating this decay. This loss of cushioning leads to bone-on-bone friction, which triggers inflammation within the joint capsule.
As a response to instability and chronic inflammation, the body attempts to stabilize the area by laying down new bone, leading to the formation of bone spurs, or osteophytes, around the joint edges. The joint capsule and surrounding ligaments may also thicken, a process called hypertrophy. These structural changes—cartilage loss, inflammation, and bone overgrowth—are the hallmarks of degenerative facet disease, restricting movement and causing irritation to the small sensory nerves that innervate the joint.
Recognizing the Pain Signals
The pain associated with degenerative facet disease is typically felt as a dull, localized ache and stiffness, most commonly in the lower back. This discomfort can be referred to other regions, such as the buttocks, hips, or the back of the thigh, but it rarely travels below the knee. The pain pattern is often non-dermatomal, meaning it does not follow the path of a single nerve root.
A defining characteristic is that the pain tends to worsen with movements that compress the joints, such as standing for long periods, walking, or leaning the spine backward (extension). Conversely, patients often find relief when they sit down or lean forward (flexion), as these actions open the joint space and reduce pressure. Stiffness is often more noticeable in the morning or after inactivity, improving slightly as the patient moves.
It is important to differentiate this referred pain from true sciatica, which is often a sharp, electric, or burning pain that radiates down the leg and is typically caused by nerve root compression. While advanced facet disease can sometimes lead to nerve root irritation and sciatica-like symptoms, the classic presentation is a deep, aching pain confined to the back and upper leg.
How Doctors Confirm the Diagnosis
Diagnosing degenerative facet disease can be challenging because imaging findings often do not correlate perfectly with a patient’s symptoms; many people without pain show signs of degeneration on scans. The diagnostic process begins with a detailed medical history and a physical examination to identify movements that reproduce the patient’s pain, such as pain upon extension and rotation.
Imaging studies, including X-rays, CT scans, and Magnetic Resonance Imaging (MRI), are used to visualize the extent of the arthritic changes and to rule out other possible causes of back pain. X-rays may show characteristic signs like joint space narrowing, bone spurs, and joint enlargement, while MRI can provide detail on inflammation and soft tissue involvement. Imaging alone is considered insufficient for a definitive diagnosis of facet pain.
The standard procedure for confirming the facet joint is the pain generator is a diagnostic block, which involves injecting a local anesthetic near the sensory nerves supplying the joint, known as the medial branch nerves. If the patient experiences significant pain relief—typically defined as 80% or more—after the injection, the diagnosis of facet-mediated pain is established with high confidence. This functional test provides the objective data necessary to guide subsequent treatment.
Current Management and Treatment Strategies
Management of degenerative facet disease begins with a conservative approach focused on reducing pain and inflammation while improving spinal function. Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used to manage acute pain flare-ups and decrease joint inflammation. Lifestyle modifications, such as maintaining a healthy weight and using heat or cold therapy, can also provide relief.
Physical therapy is a cornerstone of non-interventional treatment, aiming to restore proper posture and strengthen the core and paraspinal muscles. A stronger core musculature helps to stabilize the spine and reduce the load placed on the arthritic facet joints during daily activities. Patients are also taught to avoid movements that aggravate the condition, particularly excessive extension and rotation.
If conservative methods fail to provide adequate relief, interventional treatments are considered.
Interventional Procedures
Facet joint injections, which involve placing a combination of a steroid and a local anesthetic directly into the joint or around the medial branch nerves, can offer longer-lasting pain relief and reduce inflammation.
Another procedure is radiofrequency ablation (RFA), where a small electrical current is used to heat and temporarily deactivate the medial branch nerves responsible for transmitting pain from the joint.
RFA is an outpatient procedure that can provide pain relief lasting from six months up to a year or more, offering a significant window for patients to engage in physical therapy and long-term rehabilitation. Surgical options may be discussed for the small percentage of patients whose symptoms remain debilitating despite conservative and interventional measures. These are generally reserved for cases complicated by nerve compression or spinal instability and may involve procedures like spinal fusion to permanently stabilize the painful motion segment.