A bump on your knuckle is an unusual lump or swelling on or near your finger joints. These formations are common, and while they can cause concern, many underlying causes are not serious. A knuckle bump is a symptom pointing to various potential conditions, not a diagnosis itself.
Common Causes of Knuckle Bumps
A frequent cause of knuckle bumps is a ganglion cyst, a fluid-filled sac developing near joints or tendons. These cysts often appear on the back of the wrist or fingers and can vary in size. They are usually harmless and painless, but can become tender if they press on a nerve or other tissues.
Bony enlargements are another common reason for knuckle bumps, particularly those associated with osteoarthritis. Heberden’s nodes are hard, bony lumps that form on the distal interphalangeal (DIP) joints, which are the finger joints closest to the fingertip. Bouchard’s nodes, similarly, are bony growths that appear on the proximal interphalangeal (PIP) joints, located at the middle of the fingers. Both types of nodes result from cartilage breakdown within the joint, leading to bone spurs and often accompanied by pain, stiffness, and reduced range of motion.
Trauma or injury to the hand can also cause a knuckle bump. A past fracture or sprain might result in a bony callus, new bone formed during healing. Repeated friction or pressure can also lead to calluses or corns, which are thickened skin.
Inflammatory conditions like gout or pseudogout can cause sudden, painful, and inflamed knuckle bumps. Gout results from uric acid crystal accumulation, while pseudogout involves calcium pyrophosphate crystals. These deposits trigger inflammation, leading to tenderness, warmth, and swelling. Rheumatoid arthritis, an autoimmune condition, can form rheumatoid nodules. These firm lumps develop under the skin, often over joints like the knuckles. They are usually firm and painless unless they interfere with movement or press on nerves.
Another benign bump is an epidermoid cyst, formed when surface skin cells become trapped beneath the skin, creating a sac filled with keratin. These cysts are harmless and vary in size and shape. Less commonly, knuckle pads, a type of fibromatosis, can cause noncancerous, skin-colored, firm growths on finger joints.
Understanding Accompanying Symptoms
Observing additional symptoms alongside a knuckle bump can provide clues about its underlying cause. Pain or tenderness when touching the bump or moving the affected finger can suggest inflammation, injury, or conditions like arthritis. This pain might indicate pressure on a nerve or an active inflammatory process within the joint.
Stiffness or limited range of motion in the affected finger might point towards joint involvement, such as osteoarthritis. Redness and warmth around the bump are signs of inflammation, potentially indicating an infection or an inflammatory arthritis like gout.
Changes in the skin over the bump, such as discoloration, roughness, or breaks, could suggest a skin issue, repeated trauma, or an infection. The speed of appearance is also relevant; sudden onset might suggest an acute injury or inflammatory flare-up, while gradual development could indicate a chronic condition. If the bump changes in size, becoming larger or smaller, it could be characteristic of a fluid-filled cyst.
When to Seek Medical Attention
Consult a healthcare professional if a knuckle bump causes severe or worsening pain that interferes with daily activities.
Rapid growth or a noticeable change in the bump’s appearance, such as an irregular shape or new discoloration, should also prompt a visit to a doctor. Signs of infection, including increasing redness, warmth, pus discharge, or a fever, require immediate medical attention to prevent potential complications.
If the bump limits normal hand or finger function, making it difficult to grasp objects or perform everyday tasks, seek medical assessment. Numbness or tingling sensations in the finger can indicate nerve compression, also warranting professional evaluation. Medical advice is also prudent if the bump appeared following a specific injury or trauma.
Diagnosis and Treatment Approaches
When evaluating a knuckle bump, a doctor typically begins with a thorough physical examination, visually inspecting the bump and gently pressing on it to assess its consistency, tenderness, and mobility. The medical history is also reviewed, including questions about when the bump first appeared, any associated symptoms, and relevant past medical conditions. This initial assessment helps narrow down the potential causes.
Imaging studies are often used to gain a clearer picture of the underlying structures. X-rays can reveal bone abnormalities, such as bone spurs or joint space narrowing indicative of arthritis. Ultrasound imaging is useful for visualizing soft tissue structures and confirming fluid-filled cysts. A magnetic resonance imaging (MRI) scan may be performed to provide detailed images of soft tissues, tendons, and ligaments. If a cyst is suspected, fluid aspiration may be performed for analysis, or a biopsy might be taken for suspicious growths to determine their nature.
Treatment approaches for knuckle bumps vary widely depending on the diagnosed cause. For small, painless, and benign bumps, observation may be the only recommendation. Conservative management often involves rest, applying ice to reduce swelling and pain, and using over-the-counter pain relievers such as nonsteroidal anti-inflammatory drugs (NSAIDs). Splinting may be used to immobilize the affected joint and promote healing. Steroid injections can be administered to reduce inflammation in certain conditions.
Surgical intervention is generally considered when conservative measures have not provided relief, or if the bump causes significant pain, rapid growth, or functional impairment. For conditions like severe arthritis or symptomatic ganglion cysts, surgical removal may be an option. The decision for surgery is tailored to the individual case and is a last resort for benign conditions.