A thumb sprain happens when you injure the tissues in your thumb that connect the bones in a joint. These tissues, known as ligaments, keep your bones in place when the joint moves. In your thumb, several ligaments help you grab objects, pinch, and make a fist.

A thumb sprain is much less serious than a broken thumb because the ligament or bone isn’t broken or torn. A broken bone or a torn ligament may require more long-term treatment.

Read on to learn more about how to know if you’ve sprained your thumb, what can cause a sprain, and how it’s treated.

When you sprain your thumb, you’ll usually feel pain, discomfort, and stiffness at the base of your thumb near the palm. You may have trouble grabbing or pinching objects, or barely be able to move your thumb.

You’ll also see swelling and bruising around the base of your thumb. The pain and swelling usually fades after a few weeks if you rest your thumb and use ice to reduce swelling. Learn more about using cold therapy to ease inflammation and swelling.

Your thumb gets sprained when a ligament gets injured or stretched beyond its normal range of motion.

A thumb sprain can be caused when you hit your thumb forcefully against a hard surface or bend your thumb too far in one direction. Trying to soften a fall with your outstretched hand and hitting your thumb on the ground is the most common cause of a thumb sprain.

Sprained thumbs are also common in sports that require you to use your hands, such as football, volleyball, rugby, or basketball. Read about how minor sports injuries can be treated at home.

The ulnar collateral ligament (UCL) is the most common ligament involved in a thumb sprain. This ligament is at the base of your thumb near your palm at the metacarpophalangeal joint (MCPJ). It keeps your thumb from bending too far or dislocating.

A sprained thumb is sometimes called skier’s thumb because you can easily injure your thumb’s UCL if you hit your thumb at high speeds against a skiing pole. It’s also sometimes called gamekeeper’s thumb because of how common a chronic UCL sprain is among gamekeepers. These people frequently use their thumbs and index fingers to break the necks of small animals, which weakens or sprains the UCL over time.

To diagnose a sprain, your doctor will first move your thumb in various directions to see how it’s affected by a damaged ligament.

Then your doctor may take X-rays of your thumb and hand to see any damage to your UCL, bones, or muscles, especially if your doctor suspects that you fractured or broke a bone. They might take X-rays of both thumbs to compare your sprained thumb to your other thumb.

Your doctor may also do a stress X-ray. In this test, you doctor puts pressure on your thumb during an X-ray to see how the damaged UCL looks when it’s being strained. Your doctor may inject a local anesthetic into your thumb if the pressure is too painful.

See your doctor as soon as possible after a thumb injury. Leaving a sprain or minor fractures untreated can cause you to permanently lose thumb function.

Nonsurgical treatments

Right after you’ve sprained your thumb, use the PRICE method:

  • Pressure: Press down on the area of the sprain to keep swelling down.
  • Rest: Move your thumb as little as possible to keep the sprain from getting worse.
  • Ice: Fill a bag with ice and put it on the area of the sprain to reduce pain and swelling.
  • Compression: Wrap the area of the sprain with elastic wrap to keep pressure on the sprain.
  • Elevation: Keep your hand lifted above your heart to reduce swelling and internal bleeding.

Use athletic tape to keep your thumb attached to your index finger. This stops the thumb from moving so that the ligament isn’t damaged any further.

To treat a minor sprain, your doctor will have you wear a thumb spica splint or a cast to keep your thumb from moving. After about six weeks, the splint or cast is removed.

Your thumb will be stiff after not using it for six weeks, so your doctor will then recommend exercises to get back full control of your thumb. Repeat these exercises 8–12 times several times a day.

  • Bend the top part of your thumb back and forth.
  • Hold the base of your thumb and bend it so that the thumb touches your palm.
  • Touch the tip of your thumb to the tip of each finger in succession.

Surgical treatments

You may need surgery if your UCL is torn or if a splint or cast doesn’t help. This surgery can repair or reattach the ligament and any tissue or bones that may have been fractured or torn out of the joint when you injured your thumb.

This surgery doesn’t take long. You should be able to go home the day of the procedure after general anesthesia has worn off. You’ll follow up with your doctor in about a week and will then need to wear a cast for three to four weeks.

Cost of this surgery varies based on your health insurance plan and your surgeon. Costs range from $5,000 to $15,000 or more.

A mild sprain should heal in about six weeks if you wear a splint or cast and do rehabilitation exercises. A more serious sprain may take several months to heal before you regain most of your thumb’s function again, especially if you had UCL surgery.

While your thumb is healing, don’t play any sports that involve your hands or that could cause you to injure your thumb again. Try to avoid activities that could put stress on your thumb or injure the ligament again for at least a month. Ask your doctor before doing any manual labor or driving a vehicle.

Thumb sprains aren’t usually serious and can easily be treated without long-term complications.

See your doctor right away after you sprain your thumb. Leaving it untreated can cause your thumb to become weak or unstable. You can also develop arthritis in your joint if the ligament isn’t repaired.

To prevent a sprained thumb:

Tips

  • Exercise or play sports only when you’re well rested.
  • Wear all recommended safety equipment when you play sports.
  • Stretch your muscles for a few minutes before you do any kind of exercise.
  • Eat a balanced diet to maintain a healthy weight.
  • Exercise on flat, even terrain.
  • Stretch your hand and finger muscles every day.
  • Wear exercise shoes that fit well so that you don't trip on them.