Skier’s thumb is a sprain or tear of the ligament on the inner side of your thumb, at the large knuckle where the thumb meets the hand. It happens when the thumb is forced sharply outward and backward, most commonly during a fall while holding a ski pole. The injury ranges from a mild stretch to a complete tear, and it can seriously weaken your ability to grip and pinch if left untreated.
How the Injury Happens
The ligament involved sits along the inside edge of your thumb’s main knuckle joint. Its job is to stabilize the thumb when you pinch, grip, or push against objects. When you fall while skiing, the pole handle can catch against the ground or snow and force the thumb outward at an extreme angle. That sudden hyperextension and sideways bending overloads the ligament beyond what it can handle.
Skiing is the most common cause, but any forceful bending of the thumb in the wrong direction can produce the same injury. It shows up in football, basketball, and other sports where the thumb gets jammed or caught. The name “gamekeeper’s thumb” refers to the same ligament, but in that case the damage comes from repetitive stress rather than a single event. Scottish gamekeepers historically developed chronic looseness in the ligament from repeatedly breaking the necks of small game. Skier’s thumb, by contrast, is typically a sudden, acute injury.
What It Feels Like
The hallmark symptoms are pain and swelling along the inner side of your thumb, right at the base knuckle. You’ll likely notice bruising within a day or two. The most telling sign is weakness when you try to pinch something between your thumb and index finger, like turning a key or opening a jar. That pinch relies heavily on the ligament that’s been damaged, so even mild injuries make these everyday tasks noticeably harder.
With a partial tear, you’ll have pain but the joint still feels stable when you move it. A complete tear feels different: the thumb may seem loose or wobbly, and gripping anything firmly becomes painful or nearly impossible. Some people also feel a palpable lump on the inner side of the thumb where the torn ligament has bunched up.
Grades of Severity
Ligament injuries are graded on a three-point scale based on how much of the tissue is damaged:
- Grade 1: The ligament is stretched but intact. You’ll have pain and mild swelling, but the joint remains stable.
- Grade 2: A partial tear. The joint is somewhat loose, with more swelling and a noticeable loss of grip strength.
- Grade 3: A complete tear. The joint is unstable, meaning the thumb bends sideways far more than it should. Testing typically shows more than 35 degrees of sideways movement, or at least 15 degrees more than the uninjured thumb.
Why Some Tears Won’t Heal on Their Own
One complication makes skier’s thumb unique among ligament injuries. When the ligament tears completely, the torn end can flip over a sheet of tissue from a nearby muscle, getting trapped on the wrong side of it. This is called a Stener lesion. The muscle tissue acts like a barrier between the two torn ends, physically preventing them from reconnecting, no matter how long you immobilize the thumb. This happens in a significant portion of complete tears and is the primary reason surgery becomes necessary.
Because a Stener lesion can’t heal without surgical repair, getting an accurate diagnosis matters. If a complete tear is treated with a splint alone and a Stener lesion is present, the thumb will remain chronically unstable.
How It’s Diagnosed
A physical exam is usually the starting point. Your doctor will press along the ligament to locate the tenderness and then gently stress the thumb sideways to assess stability. If the joint opens up significantly more than the other thumb, that points toward a complete tear. A bone fragment displacement of more than 1 millimeter, or one that’s rotated out of position, also indicates a more serious injury.
Imaging often follows the physical exam. X-rays can reveal whether a small piece of bone was pulled off along with the ligament. MRI and ultrasound allow direct visualization of the soft tissue to distinguish a partial tear from a complete one. Ultrasound has a particular advantage here: the examiner can gently stress the thumb during the scan, which improves the ability to see the extent of the tear in real time. This dynamic imaging helps determine whether the ligament is merely stretched, partially torn, or fully ruptured and displaced.
Treatment for Partial Tears
Grade 1 and most grade 2 injuries heal without surgery. The standard treatment is immobilization in a thumb spica splint or cast, which holds the thumb still while keeping the rest of the hand free to move. During the first four weeks, you’ll be encouraged to keep your fingers and wrist moving with gentle range-of-motion exercises to prevent stiffness and reduce swelling.
Around four to six weeks after the injury, you’ll begin carefully moving the thumb itself, starting with small, controlled bending motions several times a day. The goal is gradual: mid-range motion first, then progressively wider arcs. Lateral stress on the thumb is avoided during this phase. By about eight weeks, passive stretching and early strengthening exercises begin, typically using therapy putty or resistive sponges to rebuild pinch and grip strength. You continue until the injured thumb comes within 5 to 10 degrees of the motion on your uninjured side.
When Surgery Is Needed
Complete tears, particularly those with a Stener lesion, require surgical repair. Surgery is also indicated when the joint has no firm endpoint during stress testing, or when a bone fragment is displaced, rotated, or involves more than one-third of the joint surface. The procedure reattaches the torn ligament to the bone, sometimes using small anchors.
After surgery, the thumb is immobilized for about four weeks. If bone anchors were used for the repair, gentle active motion can start as early as three weeks. The rehabilitation progression mirrors the non-surgical path but moves a bit more cautiously. Passive stretching and light strengthening begin around 8 to 12 weeks after surgery. All early exercises are done with the thumb held inward to protect the repair from sideways stress. Some patients need a custom dynamic splint around five weeks to help regain bending or straightening if progress stalls.
Return to Activity
Recovery timelines vary widely depending on the severity and whether surgery was involved. A study of NFL players who underwent surgical repair found that about 41% returned to sport in less than 6 weeks, another 18% returned between 6 and 12 weeks, and the remaining 41% took longer than 12 weeks. For non-athletes or those with partial tears treated in a splint, a return to normal daily activities typically falls in the 8 to 12 week range, with full grip strength taking longer.
Progressive strengthening through the later phases of rehab is important. Pinch strength and grip endurance are the last things to fully return. Therapy putty exercises targeting lateral pinch, three-point pinch, and general gripping are the standard tools for rebuilding that strength, usually done once or twice daily.
Reducing Your Risk on the Slopes
Preventing skier’s thumb comes down to what happens during a fall. Research has shown that strapless poles alone don’t reduce the incidence of the injury, but learning to release the pole during a fall does lower the risk. If the pole isn’t in your hand when you hit the ground, it can’t lever your thumb into a dangerous position. Some ski instructors teach the habit of opening your hands and letting go of the poles the moment you feel yourself falling. Pole grips with finger grooves or built-in guards can also help redirect force away from the thumb, though the most effective strategy remains simply dropping the pole.