Arthritis in the back is a general term describing the inflammation of spinal joints, which causes pain and stiffness. The most common form is osteoarthritis of the spine (spondylosis), which involves the gradual breakdown of joint cartilage due to wear and tear. Less frequently, back arthritis can be caused by inflammatory conditions like ankylosing spondylitis, an autoimmune disease affecting the joints and ligaments of the spine.
The Structures Affected by Spinal Arthritis
The primary structural component affected by back arthritis is the facet joint (zygapophyseal joint), which are small, paired synovial joints located at the back of the vertebrae. These joints guide and limit the spine’s motion, allowing for bending and twisting while maintaining stability. Each facet joint is lined with smooth cartilage that allows the bones to glide over one another without friction.
Arthritis begins when this protective cartilage thins, roughens, and wears away, leading to bone-on-bone contact. This friction triggers inflammation and pain within the joint capsule. Facet joint deterioration is often linked to the degeneration of the intervertebral discs, the large cushions between the vertebrae.
When the intervertebral discs lose height and hydration (degenerative disc disease), the mechanical stress they normally absorb is transferred to the facet joints. This increased load accelerates the breakdown of the facet joint cartilage, contributing to the arthritic process. The combined degeneration compromises the overall stability of the spinal segment.
How the Pain and Stiffness Manifest
The subjective experience of spinal arthritis is characterized by a deep, aching pain often localized in the lower back (lumbar spine) and neck (cervical spine). This pain is typically mechanical, meaning it worsens with specific movements, such as standing, walking, or extending the spine backward. Conversely, pain frequently improves when resting or leaning forward, which slightly opens the spinal joints and relieves pressure.
A defining feature is stiffness, known as the “gelling phenomenon,” which is most pronounced upon waking in the morning or after periods of prolonged inactivity. This stiffness can make it difficult to straighten the back or change positions and may persist for 30 minutes or more. As the day progresses and the spine moves, the joints often loosen up, and symptoms temporarily lessen.
The discomfort often stays localized to the back, but it can radiate into the buttocks, groin, hips, or thighs, though it rarely extends below the knee. Loss of flexibility and reduced range of motion are common, as the body unconsciously limits movement to avoid painful joint friction.
What Diagnostic Imaging Reveals
Diagnostic imaging provides objective evidence of the structural changes occurring in the spine. X-rays, Computed Tomography (CT) scans, and Magnetic Resonance Imaging (MRI) are commonly used to visualize these degenerative features. The most recognizable sign on an X-ray is the narrowing of the joint space between the facet joints, reflecting the loss of cartilage volume.
Imaging frequently captures the formation of osteophytes, or bone spurs, which are abnormal bony outgrowths developing around the edges of the facet joints and vertebral bodies. These spurs are the body’s attempt to stabilize the unstable joint, but they can narrow the passages for spinal nerves, leading to irritation and pain. CT scans are effective at detailing these bony changes and their impact.
Another finding is subchondral sclerosis, which appears as increased bone density directly beneath the deteriorated cartilage surface. This hardening of the bone is a reaction to the increased stress placed upon it due to the loss of the protective cartilage layer. Imaging may also reveal subchondral cysts or, in advanced cases, thickening of ligaments like the ligamentum flavum, which contributes to spinal canal narrowing.
Distinguishing Arthritis from Other Back Pain
Differentiating back arthritis from other common causes of back pain, such as acute muscle strain or a herniated disc, depends on the pattern and duration of symptoms. Arthritis pain is typically chronic and progressive, developing slowly over months or years. In contrast, a muscle strain has a sudden, acute onset, often following an injury. Strain pain is usually localized and improves quickly with rest within a few weeks.
Pain from a herniated disc is characterized by neurological symptoms, which are rare in uncomplicated spinal arthritis. A herniated disc often causes sharp, shooting pain that radiates down the leg (sciatica), accompanied by numbness, tingling, or muscle weakness. This radiating pain is caused by the disc material pressing directly on a spinal nerve root.
Arthritis pain, being mechanical, often feels better after the initial morning stiffness wears off, but it may worsen toward the end of the day or after prolonged activity. Disc-related pain is frequently aggravated by activities that increase pressure within the disc, such as prolonged sitting, coughing, or bending forward. Recognizing these distinct patterns is important for identifying the source of chronic back discomfort.