The spine houses small, paired structures known as facet joints, also referred to as zygapophyseal or apophyseal joints. Located at the back of each spinal segment, these joints play a significant role in enabling the spine’s extensive range of motion while providing stability. Their proper function is integral to maintaining spinal health and flexibility.
Anatomy and Function of Facet Joints
Facet joints are found along the entire spinal column, from the cervical (neck) region, through the thoracic (mid-back) area, and down to the lumbar (lower back) spine. Each spinal motion segment contains two facet joints, one on each side, linking the superior articular process of one vertebra with the inferior articular process of the vertebra directly above it. These joints are classified as synovial joints, meaning their bone ends are covered with articular cartilage.
A joint capsule, composed of connective tissue and ligaments, surrounds each facet joint, creating a sac. Inside this capsule, synovial fluid acts as a lubricant, reducing friction and providing nourishment to the cartilage. The orientation of these joints varies by spinal region; for instance, cervical facet joints are angled at about 45 degrees, allowing for flexion, extension, lateral flexion, and rotation. Lumbar facet joints, however, are oriented closer to 90 degrees, primarily facilitating flexion and extension while limiting excessive rotation and anterior gliding to protect the spinal cord.
Common Causes of Facet Joint Pain
Facet joint pain often arises from factors that compromise the joint’s structure and function. Age-related degeneration, such as osteoarthritis, is a common culprit, leading to wear and tear of the cartilage within the joints. As the cartilage erodes, bones may rub together, triggering inflammation and pain. This process can also result in the formation of bone spurs and joint enlargement.
Injuries, such as whiplash or sports trauma, can also damage facet joints. Repetitive stress, poor posture, and occupations involving frequent bending, twisting, or heavy lifting can place excessive strain on these joints, accelerating their degeneration. Inflammatory conditions like rheumatoid arthritis or ankylosing spondylitis can contribute to facet joint pain due to inflammation of the synovium, the joint’s inner lining. When spinal discs degenerate, the reduced space between vertebrae can increase pressure on the facet joints, further contributing to their wear and tear.
Recognizing Facet Joint Pain
Recognizing facet joint pain involves observing specific symptoms and their patterns. The pain is typically localized, manifesting as a dull ache in the lower back, neck, or middle back, depending on the affected spinal region. Stiffness, particularly noticeable in the morning or after periods of inactivity, is a common complaint, often improving with movement. The discomfort frequently worsens with movements, such as twisting, extending the back, prolonged standing, or sitting.
Pain can also radiate, extending to the buttocks, hips, or thighs in cases of lumbar involvement, or to the shoulders, upper back, or even the back of the head when cervical joints are affected. It is generally characterized by referred pain rather than the sharp, shooting pain associated with nerve root compression that typically extends below the knee or elbow. While muscle spasms may occur as a protective response, severe radiating pain, numbness, or weakness in the extremities might suggest nerve involvement due to bone spurs or joint enlargement.
Diagnosis and Treatment Approaches
Diagnosing facet joint issues typically begins with a thorough physical examination and a detailed review of the patient’s medical history, including symptom patterns and duration. Imaging tests like X-rays, MRI, or CT scans can reveal changes consistent with facet arthritis, such as cartilage thinning, bone spur formation, or joint enlargement. The most definitive diagnostic tool is often a diagnostic nerve block, where an anesthetic is injected near the nerves supplying the facet joint or directly into the joint itself. If the pain significantly subsides after the injection, it strongly indicates the facet joint as the source of pain.
Treatment approaches for facet joint pain usually start with conservative methods. Physical therapy plays a significant role, focusing on exercises and stretches to improve spinal strength, flexibility, and posture. Over-the-counter anti-inflammatory medications, such as NSAIDs, can help reduce pain and inflammation, while muscle relaxers may be prescribed for spasms. Applying heat or cold therapy can also provide symptomatic relief.
If conservative measures are insufficient, interventional procedures may be considered. Corticosteroid injections, containing both a steroid and an anesthetic, can be administered directly into the facet joint or around the medial branch nerves that innervate it, providing temporary pain relief by reducing inflammation. For longer-lasting relief, radiofrequency ablation (RFA) may be performed, which uses heat to disrupt the nerve pathways transmitting pain signals from the facet joints. Surgical options, such as spinal fusion, are generally reserved for severe, unresponsive cases and are less common for isolated facet joint pain.