A thumb ligament injury occurs when the ligaments that stabilize the thumb are overstretched or torn due to excessive force. This type of injury typically happens when the thumb is forcefully bent backward, away from the palm, often as a result of falling onto an extended hand.
The most frequently affected ligament in thumb injuries is the ulnar collateral ligament (UCL), which is situated on the inner side of the joint where the thumb connects to the palm. Damage to this ligament can lead to pain, instability, and a loose sensation in the thumb, potentially impairing the ability to grip or pinch objects effectively.
Treatment often includes immobilizing the thumb with a splint or cast to allow the ligament to heal. In cases of severe ligament tears or complete ruptures, surgical intervention may be required to restore the joint’s stability.
Description
Ligaments are robust, fibrous tissues that connect bones to other bones, providing stability while allowing for movement within the joints. In the thumb, these ligaments play a crucial role in maintaining proper bone alignment and joint function.
A sprain occurs when a ligament is stretched beyond its normal range, potentially causing small, incomplete tears in its fibers, known as partial-thickness tears. Although these tears do not sever the ligament completely, they can still result in pain and dysfunction.
Grades of Thumb Sprains
Thumb sprains are classified according to the severity of ligament damage:
- Grade 1 (mild): The ligament is overstretched but remains intact without any tears.
- Grade 2 (moderate): The ligament experiences partial tearing, which may lead to some functional limitations.
- Grade 3 (severe): The ligament is either completely torn in the middle or detached from its bone attachment, often accompanied by an avulsion fracture, where a small piece of bone is pulled off with the ligament. Such injuries require medical or surgical intervention.
Understanding Ulnar Collateral Ligament (UCL) Injuries in the Thumb
The ulnar collateral ligament (UCL) is a sturdy band of tissue located along the inner side of the metacarpophalangeal (MCP) joint, where the thumb connects to the palm. This ligament provides crucial stability during pinching and grasping actions.
A UCL injury in the thumb is frequently referred to as “skier’s thumb” because it often occurs when falling with a ski pole in hand. However, this ligament can also sustain damage from repetitive stress, such as twisting or grasping motions, resulting in a chronic condition known as “gamekeeper’s thumb.” This term originated from Scottish gamekeepers who often suffered from this type of injury due to their work managing wildlife.
The UCL can tear in various ways, including:
- Detachment from its attachment at the base of the thumb’s first bone (proximal phalanx)
- Separation from the metacarpal bone, where it originates
- A tear across its middle, which is less common
Causes of Thumb Sprain
A thumb sprain occurs when a strong force bends the thumb backward, away from the palm, resulting in the stretching or tearing of the ulnar collateral ligament. This type of injury commonly happens during falls onto an outstretched hand.
Thumb sprains are also frequently seen in skiers and athletes who engage in sports that involve catching or throwing, such as football, baseball, basketball, and softball.
Symptoms of a Sprained Thumb
The symptoms of a thumb sprain can vary based on the severity of the injury:
- Pain may or may not be present immediately after the injury.
- Bruising, tenderness, and swelling can develop around the base of the thumb, near the palm.
- If the ulnar collateral ligament is fully torn, a lump or swelling may form on the inner side of the thumb due to the retracted end of the ligament. Additionally, the thumb joint may feel loose or unstable.
- Difficulty grasping objects between the thumb and index finger is a common sign.
Prompt evaluation by a doctor is essential, even for mild thumb sprains that do not heal quickly. Accurate diagnosis and early treatment are crucial to preventing long-term complications such as chronic pain, instability, or arthritis.
Clinical photo of an unstable thumb. This patient has a complete tear of the ulnar collateral ligament.
Reproduced and adapted from JF Sarwark, ed: Essentials of Musculoskeletal Care, ed 4. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2010.
Doctor’s Examination for a Thumb Sprain
Physical Examination
During the physical exam, your doctor will:
- Inquire about how and when the injury occurred.
- Ask you to detail the symptoms you are experiencing.
- Thoroughly examine your thumb and hand. To assess whether the ulnar collateral ligament is partially or fully torn, your doctor will move your thumb into different positions to evaluate the stability of the metacarpophalangeal (MCP) joint. If the joint feels loose or unstable, it may indicate a complete ligament tear.
Imaging Studies
- X-rays: X-ray imaging is used to visualize dense structures like bones. Your doctor may order X-rays of both your injured and uninjured thumbs to check for any fractures or bone abnormalities and to compare the joint alignment. In cases of suspected ligament tears, a specific type of X-ray called a stress X-ray might be performed. This involves applying tension to the thumb while capturing the X-ray to better understand the joint’s stability. If this procedure causes discomfort, a local anesthetic may be administered.
- Other Imaging Tests: If additional details are needed to assess the severity of the injury, your doctor may recommend magnetic resonance imaging (MRI) or an ultrasound. These advanced imaging techniques can provide more information about the extent of ligament damage, aiding in the decision-making process for treatment and guiding your safe return to activities.
During a stress X-ray, the doctor applies tension to the thumb to test the stability of the MCP joint.
Reproduced from JF Sarwark, ed: Essentials of Musculoskeletal Care, ed 4. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2010.
Stress X-ray showing an unstable MCP joint. The abnormal opening of the joint (arrow) is a sign that the ulnar collateral ligament is completely torn.
Reproduced from TR Johnson, LS Steinbach (eds.): Essentials of Musculoskeletal Imaging. Rosemont, IL. American Academy of Orthopaedic Surgeons, 2004, p. 378.
Treatment Options for a Sprained Thumb
The appropriate treatment for a sprained thumb depends on the injury’s severity.
Home Care
For mild thumb sprains, home treatment with the RICE protocol can be effective:
- Rest: Avoid using your hand for at least 48 hours to prevent further injury.
- Ice: Apply ice immediately after the injury to reduce swelling. Use cold packs for 20-minute intervals several times a day, but avoid placing ice directly on the skin.
- Compression: Use an elastic compression bandage to help control swelling. Ensure it is not too tight to avoid restricting blood flow.
- Elevation: Keep your hand elevated above heart level as much as possible.
Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or aspirin can help alleviate pain and swelling. If symptoms persist beyond 48 hours, consult a doctor for further evaluation.
Nonsurgical Treatment
For moderate thumb sprains, immobilization is typically recommended. Your doctor may use a bandage, thumb spica cast, or splint to stabilize the joint while it heals. To reduce pain and swelling, applying a cold pack twice daily for the first 2-3 days post-injury can be beneficial; however, ice should not be placed directly on the skin.
Depending on the extent of the injury, you may need to wear the splint or cast continuously. It is crucial to avoid any pressure or resistance on the thumb until your doctor approves. Immobilization can sometimes lead to stiffness in the joint, so your doctor may suggest stretching exercises to help restore full range of motion gradually.
