A sprained thumb occurs when the ligaments that support the thumb stretch beyond their limits or tear. This usually happens when a strong force bends the thumb backwards, away from the palm of the hand. The most common way for this to occur is by falling onto an outstretched hand.
Most thumb sprains involve the ulnar collateral ligament, which is located on the inside of the knuckle joint. A tear to this ligament can be painful and may make your thumb feel unstable. It may also weaken your ability to grasp objects between your thumb and index finger.
Treatment for a sprained thumb usually involves wearing a splint or cast to keep the thumb from moving while the ligament heals. For more severe sprains, surgery may be needed to restore stability to the joint.
Ligaments are strong, fibrous tissues that connect bones to other bones. The ligaments in the thumb help keep the bones in proper position and stabilize the joint.
Sprains can range from a stretch or tiny tear in the fibers that make up the ligament to a complete tear through the ligament or through its attachment to the bone.
Grades of Thumb Sprains
Sprains are graded, depending on the degree of injury to the ligaments
The most common ligament to be injured in the thumb is the ulnar collateral ligament. This strong band of tissue, which is attached to the middle joint of the thumb (the metacarpophalangeal or MCP joint), keeps your thumb stable so that you can pinch and grasp things.
A sprained thumb is often called a “skier’s thumb” because falling on the ski slopes with your hand strapped to a ski pole is a common cause of injury to the ulnar collateral ligament.
The ligament can also be injured more gradually, over time, from repetitive grasping or twisting activities. This type of chronic injury is known as a “gamekeeper’s thumb.”
The ulnar collateral ligament can tear in different ways. For example, it may be pulled off its attachment at the base of the first bone (the proximal phalanx) in the thumb or from its origin on the metacarpal bone. It can also be torn through its middle, although this is less common.
Any strong force that bends the thumb backwards, away from the palm of the hand, can stretch or tear the ulnar collateral ligament. This most often occurs by falling onto an outstretched hand.
Sprained thumbs are also common in skiers and in athletes who participate in sports that involve catching and throwing a ball, like football, baseball, and basketball.
Depending on the severity of the sprain, pain may or may not occur at the time of the injury. You may have bruising, tenderness, and swelling around the base of your thumb, near the palm.
If the ulnar collateral ligament is completely torn, the end of the ruptured ligament may cause a lump or swelling on the inside of the thumb. Your thumb joint may also feel loose or unstable. You may have difficulty grasping items between your thumb and index finger.
Your doctor will want to know how and when your injury occurred and will ask you to describe your symptoms. He or she will then carefully exam your thumb and hand.
To help determine if the ulnar collateral ligament is partially or completely torn, your doctor will move your thumb in different positions to test the stability of the MCP joint. If the joint is loose and unstable, it is an indication that the ligament may be completely torn.
X-rays. X-rays provide images of dense structures, such as bone. Your doctor may order x-rays of your thumb and hand to ensure that you do not have an avulsion fracture or any broken bones. He or she may also take an x-ray of your uninjured thumb to compare it to the injured thumb.
A special type of x-ray, called a stress x-ray, may also be ordered. During this test, your doctor will apply tension to your thumb while it is being x-rayed to learn more about the stability of the MCP joint. If the test causes pain, you may be given an injection of a local anesthetic.
Other imaging studies. If more information is needed, a magnetic resonance imaging (MRI) scan or an ultrasound may be ordered. These tests can help your doctor learn more about the severity of your injury and make decisions regarding your treatment and return to activity.
Treatment for a sprained thumb depends on the severity of the injury.
Mild thumb sprains will usually improve with home treatment that includes the RICE protocol:
Related article: RICER Approach For Injuries
Additionally, nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, can help reduce pain and swelling. If pain and swelling persist for more than 48 hours, however, see a doctor.
For a moderate sprain, your doctor will probably immobilize your thumb joint with a bandage, thumb spica cast, or splint until it heals.
To ease pain and swelling, you can apply a cold pack to your thumb twice a day for 2 to 3 days after the injury. Do not apply ice directly on your skin, instead, wrap ice packs in at least 2 layers of towels before applying.
Depending on the severity of the injury, you may be instructed to wear the splint or cast at all times.
It is important that you avoid applying any pressure or resistance to your thumb until you are permitted by your doctor. Because immobilization may cause some stiffness in your thumb joint, your doctor may recommend hand therapy with us to help you regain full range of motion.
For a severe sprain, surgery may be needed to restore the stability of your thumb joint and help you regain function. Surgery involves reconnecting the ligament to the bone and/or repairing the avulsion fracture using a pin, screw, or special bone anchor. After surgery, you may have to wear a short arm cast or a customized splint for 6 to 12 weeks to protect the thumb ligament while it heals.
When diagnosed and treated properly with early hand therapy intervention, most thumb sprains will heal well with no residual complications.
That being said, patients who ignore and don't get their sprained thumbs treated hoping that it will heal on its own may lead to long-term problems, including
If these late complications develop, corrective surgery may be needed to rebuild the ligament using tissue from your upper arm. If there is significant arthritis, you may also require to undergo a joint fusion procedure may be needed to address both the arthritis and the instability of the thumb metacarpophalangeal (knuckle) joint.