The movement of the hand and fingers relies on tendons, which are strong, cord-like structures. Tendons connect the muscles in the forearm and hand to the bones of the fingers, allowing for the purposeful action of bending and straightening the digits. When a finger tendon is torn or cut, this mechanical link is disrupted, immediately impairing the finger’s ability to move normally. These injuries often result from minor cuts or forceful hyperextensions and are frequently misidentified as a simple sprain or deep cut.
Visual Indicators of a Ruptured Tendon
A torn finger tendon often presents with immediate external changes. The first sign is rapid swelling, the body’s inflammatory response to tissue damage and internal bleeding. Bruising (ecchymosis) may also develop quickly around the injury site as blood vessels are often damaged along with the tendon.
The most telling visual sign is the altered resting position of the injured finger. Normally, the relaxed hand displays a gentle, progressive curl, known as the digital cascade. If a flexor tendon on the palm side is completely torn, the finger loses this natural tension and will lie noticeably straighter or more extended than its neighbors.
Conversely, a complete tear of an extensor tendon on the back of the finger results in a distinct drooping appearance. An injury near the fingertip joint (Distal Interphalangeal joint) often causes the tip to fall into a bent position, commonly called a mallet finger. In severe cases, a noticeable depression or gap may be visible along the path of the tendon where the severed ends have retracted.
Functional Limitations and Key Symptoms
The mechanical loss of function is the most definitive symptom of a tendon rupture. This occurs because the muscle can no longer transmit force through the severed tendon to the bone. The primary limitation is the inability to actively perform the movement the tendon controls.
If a flexor tendon is torn, the individual cannot actively curl the finger into a fist or bend the joint closest to the palm. Similarly, an extensor tendon tear prevents the person from actively straightening or lifting the finger from a bent position. Crucially, while active movement is lost, the finger can often be moved passively by using the other hand to bend or straighten the joints.
Pain associated with a tendon tear is often sharp and immediate at the moment of injury, sometimes described as a snap or pop. Following the trauma, the area develops tenderness, particularly when pressure is applied along the line of the tendon. This is often accompanied by a dull, persistent ache that worsens when attempting to use the damaged tendon.
Differentiating Types of Tendon Injuries
Tendon injuries are classified by the extent of the tear and the tendon’s function. A partial tear involves damage to only a portion of the fibers, leaving some continuity intact. The finger may still move, but the action is often accompanied by pain, weakness, or a catching sensation.
A complete tear, or rupture, means the tendon has fully separated into two pieces. This results in the total loss of the tendon’s movement function. The muscle’s tension pulls the severed ends apart, preventing natural healing without intervention.
Tears are also categorized by location and purpose. Flexor tendons are on the palm side, facilitating bending and gripping. Extensor tendons are on the back of the hand, enabling the straightening and lifting of the digits. This distinction is important because a flexor injury impairs gripping, while an extensor injury impairs the ability to fully extend the hand.
Immediate Actions and Seeking Medical Diagnosis
Stabilizing the injured finger immediately after a suspected tendon tear prevents further damage and reduces swelling. This involves resting the hand completely and avoiding attempts to move the digit, which could cause the severed tendon ends to retract further. Applying ice to the affected area minimizes swelling and manages pain by constricting local blood vessels.
Gently compress the area, perhaps with a soft bandage, and keep the hand elevated above the level of the heart. These steps limit blood flow and reduce fluid accumulation, which makes subsequent medical examination easier. Seeking professional medical evaluation as soon as possible, ideally within 24 to 48 hours of the injury, is necessary.
Prompt evaluation is necessary because the window for optimal surgical repair is limited. A medical professional will perform specific physical tests, such as assessing the finger’s resting posture and testing active versus passive movement. Imaging tests are used to confirm the diagnosis and rule out associated injuries. X-rays check for avulsion fractures (where a piece of bone has been pulled away by the tendon), while ultrasound or MRI may visualize soft tissue damage and confirm the tear’s extent.