Osteoarthritis (OA) is the most common form of arthritis, characterized by the breakdown of cartilage that cushions the ends of bones within a joint. It causes pain, stiffness, and reduced mobility, frequently affecting the hands, knees, hips, and spine. Experiencing numbness or tingling (paresthesia) in the fingers can be concerning for people with OA. The link between joint degeneration and these nerve sensations is typically indirect, pointing to a secondary issue requiring medical investigation.
The Direct Answer: OA and Nerve Symptoms
The primary symptoms of hand osteoarthritis are pain, stiffness, and the formation of bony lumps around the joints. However, the joint’s degenerative process can irritate or compress nearby nerves, leading to numbness and tingling. One mechanism involves chronic, low-grade inflammation that occurs as cartilage deteriorates, releasing chemical mediators that can sensitize peripheral nerves.
Another way OA affects nerves is through the formation of bone spurs, known as osteophytes. These bony projections develop as the body attempts to stabilize the damaged joint. If a bone spur grows near a nerve pathway, it can physically compress the nerve, resulting in paresthesia. While OA in the finger joints typically causes localized pain, secondary effects like inflammation and structural change lead to nerve symptoms.
Cervical Spine Involvement
The most frequent cause of OA-related finger numbness and tingling originates in the neck. Degenerative changes in the cervical spine, called cervical spondylosis, involve the wearing down of vertebral discs and facet joints. This process leads to the formation of osteophytes and disc bulging, which narrow the openings where nerve roots exit the spinal column. Compression of these nerve roots is known as cervical radiculopathy, or a “pinched nerve.”
The location of the numbness and tingling depends on which nerve root is affected. For example, compression of the C6 nerve root typically causes symptoms on the thumb side of the hand, including the thumb and index finger. If the C7 nerve root is compressed, the numbness and tingling are most often felt in the middle finger. C8 nerve root compression is associated with paresthesia on the pinky-finger side of the hand.
The sensory changes travel down the arm, following the path of the irritated nerve. This explains why a problem in the spine manifests as a sensation entirely within the hand or fingers. The pain often starts in the neck or shoulder blade and radiates down the arm.
Local Compression Syndromes
Finger numbness and tingling can also result from local nerve entrapment syndromes that frequently coexist with hand or wrist osteoarthritis. Carpal Tunnel Syndrome (CTS) is the most common, involving the compression of the median nerve as it passes through the carpal tunnel in the wrist. OA of the wrist or the base of the thumb can contribute to CTS by causing swelling or structural changes that narrow the carpal tunnel space.
The characteristic symptoms of CTS include numbness and tingling in the thumb, index finger, middle finger, and the thumb side of the ring finger. These sensations are often worse at night. The ulnar nerve can also be compressed at the wrist, resulting in numbness in the little finger and the adjacent half of the ring finger.
The co-occurrence of cervical radiculopathy and a local entrapment like CTS is sometimes called “double crush syndrome.” This suggests that compression at one point, such as the neck, makes the nerve more vulnerable to compression further down its path, such as at the wrist.
Diagnosis and Management
If finger numbness and tingling are present, an accurate diagnosis is necessary to determine the source of the nerve compression. A medical evaluation includes a detailed physical and neurological exam to assess sensation, strength, and reflexes. Imaging tests are used to visualize underlying structural changes.
Plain X-rays can reveal osteophyte formation and joint space narrowing. Magnetic Resonance Imaging (MRI) is effective for evaluating soft tissues, such as spinal discs and nerve roots, to confirm cervical radiculopathy. Specialized tests like Nerve Conduction Studies (NCS) and Electromyography (EMG) pinpoint the location and severity of nerve damage, helping differentiate between a pinched nerve in the neck and one in the wrist.
Once the cause is confirmed, management focuses on relieving pressure on the affected nerve. For cervical radiculopathy, this may involve physical therapy aimed at strengthening the neck and improving posture, along with anti-inflammatory medications. For Carpal Tunnel Syndrome, initial management often includes wrist splinting and corticosteroid injections to reduce local inflammation.