Trauma to the hand often involves the thumb, which relies on a delicate blood supply to maintain function and viability. The thumb is primarily fed by branches of the radial artery, forming two main digital arteries: the ulnar and radial proper digital arteries. An injury that severs one or both of these small vessels risks severe bleeding and a lack of blood flow, which can lead to tissue death if not rapidly addressed. Recognizing the signs and seeking specialized medical attention is necessary to save the digit.
Recognizing the Signs of Arterial Damage
Identifying a digital artery injury involves recognizing both active signs of bleeding and passive signs of inadequate circulation. A severed artery typically causes profuse bleeding, often appearing bright red due to its high oxygen content. This blood may also emerge in a rhythmic or spurting pattern, reflecting the pressure from the heart’s pumping action.
The most concerning signs relate to ischemia, the lack of oxygenated blood reaching the tip of the thumb. The digit distal to the injury may quickly become noticeably paler or whiter than the surrounding skin (pallor). It will also feel cooler to the touch, and if pressure is applied to the nail bed, the color will return slowly, indicating a delayed capillary refill time.
The proper digital arteries run in close proximity to the digital nerves, forming a neurovascular bundle on each side of the thumb. Therefore, an arterial laceration is often accompanied by nerve damage, manifesting as numbness, tingling, or a complete lack of sensation. Even if only a single digital artery is severed, the injury is severe and requires repair.
Emergency First Aid Steps
The immediate priority is to control blood loss and secure professional medical care. Call emergency services or go directly to the nearest emergency room. While waiting, apply direct, firm pressure to the wound using a clean cloth, sterile gauze, or a piece of clothing.
Maintaining continuous pressure encourages clotting and slows blood flow. Simultaneously, elevate the injured hand above the level of the heart, using gravity to reduce arterial pressure at the bleeding site. If the initial cloth becomes soaked with blood, place another clean dressing directly on top of it and maintain pressure without removing the first layer.
Tourniquets are generally reserved for life-threatening, uncontrollable hemorrhage or traumatic amputation. Improvised tourniquets can cause harm by damaging underlying nerves and soft tissues. Only use a commercially made tourniquet if directed by emergency medical professionals or if direct pressure and elevation fail to control life-threatening bleeding.
Clinical Diagnosis and Surgical Repair
Upon arrival at the hospital, medical staff will assess the vascular status of the thumb to confirm the extent of the damage. A handheld Doppler ultrasound device is commonly used to listen for blood flow within the digital arteries and confirm its presence or absence distal to the injury. In complex cases, an angiogram, which involves injecting contrast dye into the vessels, may be performed to visualize the arterial network and identify the exact location of the blockage or rupture.
The definitive treatment for a severed digital artery is microsurgical repair, performed by specialized hand surgeons. This surgery requires the use of an operating microscope and specialized instruments to work with the extremely small vessels, which are often only about one millimeter in diameter. The goal is a tension-free end-to-end connection, or anastomosis, of the severed artery ends to restore continuous blood flow.
If the trauma has caused a gap or significant damage, the surgeon may need to use a vein graft, often harvested from the wrist or forearm, to bridge the distance. Due to the close anatomical relationship of the neurovascular bundle, any accompanying structures, such as tendons or digital nerves, are repaired during the same operation. Nerve repair is accomplished by fine suturing of the nerve sheath (epineurium) to enable potential nerve regeneration.
Recovery and Long-Term Outlook
Following successful surgical repair, the thumb is immobilized in a splint or cast to protect the vascular and nerve repairs. Post-operative care involves close monitoring for signs of re-occlusion, which is the formation of a blood clot that blocks the repaired artery. Patients are often kept on blood-thinning medications to minimize this risk and ensure the patency of the vessel repair.
Once the initial healing phase is complete, physical or occupational therapy is necessary to regain strength, flexibility, and range of motion. Therapy focuses on desensitization exercises and gentle stretching to prevent stiffness. Rehabilitation should only begin when cleared by the surgeon to avoid stressing the repair site.
Despite a successful operation, patients may experience long-term complications. The most common is cold intolerance, where the thumb becomes painfully sensitive to cold temperatures. Other potential issues include chronic pain, hypersensitivity, or nerve dysfunction if the nerve was damaged or scarred during the injury. Although microsurgery increases the chances of saving the digit, the recovery of full sensation and function can be a long process.