Pain located in the distal interphalangeal (DIP) joint, the small knuckle closest to the fingertip, is a common concern that often intensifies when pressure is applied. This discomfort can feel sharp when gripping an object or pressing on the finger. Located at the end of the finger, the DIP joint is susceptible to both chronic wear-and-tear conditions and acute, localized injuries or infections. The underlying issue is frequently related to changes within the joint itself or pressure from a structure immediately surrounding it.
Understanding the Distal Interphalangeal Joint
The DIP joint is a hinge joint connecting the middle and distal phalanges, the two bones that form the end of the finger. This joint allows for the flexion and extension required for fine motor skills, such as pinching, grasping, and manipulating small objects. Its position at the end of a long lever arm means it is heavily involved in nearly every hand movement.
The joint consists of bone ends covered by articular cartilage, all encased within a capsule stabilized by ligaments and moved by tendons. Because the DIP joint has relatively little protective soft tissue and is subjected to repeated mechanical stress, the cartilage is prone to degeneration. This constant engagement makes it a frequent site for degenerative changes or localized trauma.
Chronic Conditions Causing DIP Joint Tenderness
The most frequent causes of chronic DIP joint tenderness upon pressure are forms of arthritis that lead to permanent structural changes within the joint. Osteoarthritis (OA) is the most common culprit, resulting from the progressive breakdown of articular cartilage. As the cartilage erodes, the body attempts to stabilize the joint by forming bony growths, known as osteophytes, particularly on the back of the joint.
These bony enlargements at the DIP joint are called Heberden’s nodes. Applying pressure exacerbates friction between the exposed bone surfaces and irritates the surrounding soft tissues, causing sharp pain. The enlarged, stiff joint becomes tender to the touch, which is a defining characteristic of advanced finger OA.
Psoriatic Arthritis (PsA) also frequently targets the DIP joints, often causing more severe inflammatory pain than OA. PsA is a systemic inflammatory condition where the immune system attacks the joints and surrounding connective tissues. A distinctive manifestation of PsA is dactylitis, or “sausage digit,” where the entire finger becomes diffusely swollen, warm, and tender. Tenderness when pressing on the joint is caused by active inflammation of the joint lining and the entheses, where tendons and ligaments attach to the bone.
Acute and Localized Sources of Pain Upon Pressure
Pain localized to a single spot on the DIP joint when pressed often points to a non-systemic, acute issue. A digital mucous cyst, a type of ganglion cyst, commonly forms near the DIP joint, typically on the back of the finger near the nail. These cysts are filled with thick, gelatinous fluid that leaks from the joint capsule, often associated with underlying osteoarthritis.
The tense, fluid-filled sac causes tenderness when compressed, and its presence can also cause a painful groove or deformity in the fingernail due to external pressure on the nail matrix. Acute trauma, such as a hyperextension injury or jammed finger, can cause a ligament sprain or a small fracture to one of the phalanx bones. Pressing on the joint elicits immediate, sharp pain because the movement strains the injured soft tissue or directly compresses the fracture site.
Infections of the fingertip can also cause severe, throbbing pain exacerbated by pressure. A felon is a deep infection in the pulp space of the fingertip, while a paronychia is an infection around the nail fold. Because the fingertip is divided into small, tight compartments, pus buildup creates significant internal pressure. Pressing on the area intensifies this pressure, leading to sharp pain, redness, and swelling.
Medical Evaluation and Diagnostic Procedures
A healthcare professional begins the evaluation with a thorough physical examination to differentiate between potential causes. They assess the joint for range of motion, location of tenderness, warmth, redness, and characteristic features like Heberden’s nodes or dactylitis. The history of the pain—whether it was sudden or gradual, or if it followed an injury—provides important early clues.
Imaging, typically plain film X-rays, is the most common diagnostic tool. X-rays can confirm bony spurs and joint space narrowing typical of osteoarthritis, reveal a fracture or dislocation from acute trauma, or show bone erosion characteristic of PsA. If an inflammatory condition or systemic disease is suspected, blood tests may be ordered to check for inflammatory markers or specific antibodies.
Targeted Treatment Approaches
Treatment is tailored to the specific cause identified during the evaluation. For chronic conditions like Osteoarthritis, conservative management often involves nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce pain and inflammation. Activity modification and splinting can also help reduce mechanical stress on the tender joint.
When pain is persistent or severe, localized steroid injections into the DIP joint can provide temporary relief by reducing inflammation. In advanced cases of OA where pain is disabling, surgical options may include joint fusion to permanently stabilize the joint and eliminate bone-on-bone pain. Psoriatic Arthritis requires systemic treatment, frequently with disease-modifying anti-rheumatic drugs (DMARDs) or biologics, to control the underlying immune response.
Localized issues require specific interventions to relieve pressure. A painful digital mucous cyst may be treated with aspiration of the fluid or, more definitively, surgical excision to remove the cyst and the associated osteophyte that causes it. Acute infections like a felon require prompt drainage—a small incision to release the trapped pus—combined with antibiotics to prevent the infection from spreading to the bone or joint.