Tearing a tendon in the finger is a common and serious injury that significantly impacts hand function. Tendons are strong, fibrous connective tissues connecting the muscles of the forearm and hand to the finger bones. When these structures tear, either partially or completely, the connection is broken, leading to a loss of the ability to bend or straighten the affected finger. Because finger tendons are responsible for the fine motor control and dexterity of the hand, any damage requires prompt attention to restore mobility and function.
Anatomy and Why Finger Tendons are Vulnerable
The anatomy of the finger makes its tendons susceptible to injury due to their location. Fingers contain two main types of tendons: the flexor tendons, which run along the palm side and facilitate bending, and the extensor tendons, which run along the back of the hand and facilitate straightening. The flexor tendons are housed within a confined space known as the fibro-osseous tunnel, reinforced by a series of pulleys.
This intricate arrangement allows for smooth gliding but also creates vulnerability. The tendons run close to the skin surface, making them easily damaged by sharp objects. Furthermore, the narrow environment of the tendon sheath is prone to friction and scarring if the tendon is injured.
How Tendons Tear: Specific Injury Mechanisms
Finger tendons can be torn through three primary mechanisms: lacerations, avulsion injuries, and closed ruptures from blunt trauma. Lacerations, often caused by sharp objects, are the most common cause of flexor tendon injury, resulting in a clean cut that severs the connection. When a tendon is completely cut, the muscle tension pulls the severed ends away from each other, sometimes retracting the tendon into the palm or forearm.
Avulsion injuries occur when a tendon pulls so forcefully that it rips its attachment point, often taking a small piece of bone. A classic example is “Jersey Finger,” involving the flexor digitorum profundus (FDP) tendon, typically in the ring finger. This happens when the fingertip is forcibly extended while the finger is actively trying to flex, such as when a jersey is pulled away.
Closed ruptures happen without an open wound and are frequently seen in extensor tendons from blunt impact. The “Mallet Finger” injury is a common example, occurring when an extended fingertip is suddenly jammed, forcing the distal joint to bend rapidly. This forceful load causes the extensor tendon to rupture or avulse where it inserts at the fingertip, resulting in an inability to actively straighten the distal phalanx.
Identifying a Tear: Symptoms of Loss of Function
Identifying a torn finger tendon centers on the sudden loss of active motion, which varies depending on the affected tendon. A flexor tendon tear results in the inability to actively bend or curl the finger, especially at the fingertip joint. The injured finger often rests in an abnormally straight posture compared to the other fingers, which naturally maintain a slight curve.
Conversely, an extensor tendon tear causes a functional deficit in straightening the finger. This injury often presents as a permanent droop or bent appearance at the affected joint, such as the characteristic bent tip seen with a Mallet Finger. A patient can passively straighten the finger with the other hand but cannot maintain that straight position using their own muscle power.
Beyond the loss of function, the injury may be accompanied by immediate pain, significant swelling, and bruising. Some people report feeling a distinct “pop” or snapping sensation at the time of injury. If a laceration caused the tear, numbness or tingling alongside the inability to move may indicate that a nerve was also damaged, as nerves and tendons run in close proximity.
Immediate Care and Professional Treatment Options
Immediate care for a suspected finger tendon tear involves minimizing swelling and protecting the injury before seeking professional medical help. Applying ice and keeping the hand elevated above the heart helps reduce initial swelling and pain. It is important to cover any open wounds with a clean dressing and avoid attempting to move the finger vigorously, as this can cause the tendon ends to retract further.
Professional treatment must be sought urgently, ideally within the first seven to ten days, because delayed repair complicates the procedure and worsens the prognosis. A hand specialist will diagnose the injury through a physical examination, assessing the ability to move the finger against resistance, and may order an X-ray to check for any associated bony avulsion fragments.
For most complete tears, particularly flexor tendons, surgical repair is necessary. During surgery, the surgeon reconnects the tendon ends using specialized sutures, aiming to restore the structure’s continuity. Following surgery, the hand is immobilized in a protective splint, often holding the finger in a bent position to keep tension off the repair. Non-surgical management, involving specialized splinting for six to eight weeks, is often used for partial tears or specific closed extensor injuries like Mallet Finger. Regardless of the initial treatment, the recovery process requires a structured program of hand therapy and rehabilitation to prevent stiffness, regain smooth gliding motion, and restore strength.