Hip arthritis, most often osteoarthritis, can cause lower back pain, a connection often called hip-spine syndrome. This progressive condition involves the wearing away of cartilage cushioning the hip joint, leading to stiffness and pain. Because the hip and lower spine are functionally interconnected, a problem in one area often leads to symptoms in the other. When lower back pain occurs alongside hip discomfort, determining the primary source requires a careful medical evaluation.
The Biomechanical Relationship Between the Hip and Spine
The hip joint and the lower back are connected by the pelvis, forming a functional unit called the lumbopelvic complex. When the hip joint degenerates due to arthritis, the resulting pain and reduced range of motion force the body to compensate for the stiffness. This compensation is the direct mechanical cause of secondary lower back pain.
A stiff, arthritic hip restricts the normal movement required for walking, often leading to an altered gait, such as a limp. To avoid moving the painful hip, the body shifts the burden of movement to the spine and pelvis. This shift manifests as excessive tilting or rotation of the pelvis, mimicking the lost hip motion.
This compensatory movement places increased strain on the muscles, discs, and facet joints of the lumbar spine. For example, if the hip cannot fully straighten (fixed flexion deformity), the lumbar spine may increase its curve (lordosis) to allow the person to stand upright. Over time, this constant mechanical stress leads to pain and potentially degenerative changes in the spine itself.
Identifying the Primary Source of Pain
Differentiating between lower back pain originating from the hip versus the spine is a diagnostic challenge due to overlapping pain patterns. Hip arthritis pain often radiates to the buttock, groin, or side of the hip, but sometimes presents only as lower back discomfort. Examining specific movement patterns offers the first clues about the pain’s origin.
Pain that worsens with hip rotation, especially limited internal rotation, strongly indicates the hip joint is the primary source. Patients often report difficulty with activities requiring hip flexion and rotation, such as putting on socks or getting into a car. Conversely, pain originating from the spine is aggravated by specific spinal movements, like bending forward or leaning backward. Spinal pain may also present with nerve-related symptoms, such as tingling or shooting pain down the leg (sciatica).
Imaging tools like X-rays and Magnetic Resonance Imaging (MRI) help visualize joint space narrowing in the hip and any disc or nerve issues in the spine. However, a definitive diagnostic tool is often a targeted injection. By injecting a local anesthetic and a corticosteroid directly into the hip joint, a physician can temporarily numb the hip. If the patient’s lower back pain is significantly relieved immediately following the injection, it confirms the hip is the source of the referred pain.
Non-Surgical Management of Referred Pain
Treatment for secondary lower back pain must focus on addressing the underlying hip pathology, not just treating the back pain in isolation. Physical therapy is a primary intervention aimed at restoring the biomechanical balance of the lumbopelvic complex. This involves strengthening hip-stabilizing muscles, such as the gluteals and core musculature, to reduce compensatory strain on the lumbar spine.
Therapy also works to improve the hip’s range of motion and normalize the walking pattern, which reduces excessive stress placed on the lower back. Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used to reduce inflammation and pain within the arthritic hip joint. Reducing hip inflammation lessens the pain signals that trigger protective compensatory movements.
For more immediate relief, a corticosteroid injection directly into the hip joint can dramatically reduce inflammation and pain for several months. Alleviating hip pain allows the patient to move more normally, breaking the cycle of compensatory movement that causes secondary back pain. Using assistive devices like a cane can also temporarily reduce the load on the arthritic hip, decreasing stress on the spine.