Gamekeeper's Thumb

Updated: Dec 16, 2022
Author: Matthew Hannibal, MD; Chief Editor: Craig C Young, MD 


Practice Essentials

Gamekeeper's thumb is an insufficiency of the ulnar collateral ligament (UCL) of the metacarpophalangeal (MCP) joint of the thumb. Campbell originally coined the term in 1955 because the condition was most commonly associated with Scottish gamekeepers (especially rabbit keepers) as a work-related injury.[1, 2]  The injury occurred as the gamekeepers sacrificed game such as rabbits by breaking the animals' necks between the thumb and index finger of the gamekeeper and the ground. As a result, a valgus force was placed onto the abducted metacarpophalangeal (MCP) joint, leading to a ruptured ulnar collateral ligament (UCL) injury and chronic attritional injury that resulted in instability, which was accompanied by pain and weakness of the pinch grasp.

In the present day, this type of injury is typically more acute. The most common cause is a skier's hand landing on a ski pole, causing a valgus force on the thumb.[3, 4]  The term "skier's thumb" represents the more acute nature of the injury. Because stability of the thumb is important for prehension, treatment is directed toward optimizing ligament healing to restore full function.[5]


United States statistics

Gamekeeper's thumb is a fairly common injury, with an increased incidence in skiers that does not depend on the type of ski pole used. No known sex predilection is associated with this condition.

International statistics

No apparent difference exists in the international population with regard to the frequency or incidence of gamekeeper's thumb.

Functional Anatomy

The MCP joint is a diarthrodial joint that is primarily involved in flexion and extension. The static restraints and some dynamic stabilizers provide joint stability. The static restraints include the proper collateral ligament (mostly in flexion), the accessory collateral ligament (mostly in extension), the palmar plate (mostly in extension), and the dorsal capsule (limited, in flexion). The dynamic stabilizers include the thumb intrinsic and extrinsic muscles. The adductor mechanism is particularly important here, because it inserts onto the extensor expansion through its aponeurosis, which lies superficial to the UCL.

The UCL is a 4- to 8-mm X 12- to 14-mm band that originates from the metacarpal head and inserts into the medial aspect and base of the proximal phalanx of the thumb. Occasionally, when the UCL is strained, it avulses the bone at its insertion and leads to a gamekeeper's fracture, as shown in the 2 images below.

Lateral radiograph displaying a gamekeeper's fract Lateral radiograph displaying a gamekeeper's fracture.
Anteroposterior radiograph displaying a gamekeeper Anteroposterior radiograph displaying a gamekeeper's fracture.

A Stener lesion occurs when the adductor aponeurosis becomes interposed between the ruptured UCL and its site of insertion at the base of the proximal phalanx. Thus, the distal portion of the ligament retracts and points superficially and proximally. A rupture of the proper and accessory collateral ligaments must occur for this injury to happen. The UCL no longer contacts its area of insertion and cannot heal. This lesion can also be associated with a gamekeeper's fracture,[6] which can be subtle or obvious (see the images above). However, a lump or mass over the ulnar aspect of the MCP joint of the thumb does not necessarily imply a fracture; it may be the result of the Stener lesion.

Sport-Specific Biomechanics

Considerable variation may be observed in the range of flexion and extension of the thumb MCP joint. The variation of normal joints can include ranges of motion (ROMs) from 5-115° of flexion and extension. In full extension, valgus laxity averages 6° and increases to an average of 12° in 15° of flexion.


Early diagnosis of gamekeeper's thumb injuries is one of the most important factors that determines functional outcome. In thumbs with partial ligament injuries, nonoperative treatment by immobilization will yield a stable, painless thumb with nearly normal motion in most cases. In thumbs with a complete rupture that are treated operatively within 3 weeks of injury, a good to excellent result can be expected in >90% of cases.

Pain and stiffness in the affected thumb can be expected to be mild or absent, and pinch and grip strength should be nearly normal. The rate of return to former activities, including recreational sports, has been reported as high as 96%.


Chronic instability of the MCP joint can occur despite a good surgical repair, especially if motion and return to play are resumed prematurely. This instability is difficult to treat and can lead to arthritic changes in the MCP joint, as well as weak pinch grasp in the long term.




The gamekeeper's thumb injury may be caused by a valgus stress of any kind to the thumb. The most common history is a fall onto an outstretched arm with an abducted thumb. This commonly occurs in skiers with a ski pole in the hand, which prevents adduction of the thumb when the skier falls.

Other causes of gamekeeper's thumb include the following:

  • Falling onto an outstretched arm with the thumb abducted

  • Valgus-producing force on the thumb MCP joint

  • Rheumatoid arthritis

  • Generalized ligamentous laxity

Physical Examination

The contralateral, unaffected thumb should be evaluated first for ROM and valgus stability in both extension and 30° of flexion. Then, evaluate the injured thumb for swelling and pain at the ulnar aspect of the MCP joint. Ecchymosis is frequently seen.

Malik et al suggested comparison with the uninjured contralateral thumb may be unreliable in many individuals and recommended that the lack of a definite end point on stress examination to indicate a complete rupture of the ulnar collateral ligament.[7]  When the investigators assessed 200 thumbs of 100 unaffected individuals in extension and 30º of flexion, 34% of subjects showed a difference of 10º or more between the contralateral thumbs in extension; another 12% of subjects showed at least a 15º difference between thumbs. When the thumbs were examined in flexion, a difference of 10º or more was noted in 22% of the thumbs, and a 15 º difference was found in 3%.[7]





Laboratory Studies

No laboratory tests are necessary for the diagnosis of gamekeeper's thumb.

In cases that require surgical intervention, routine preoperative laboratory workup is indicated.

Imaging Studies


Before any manipulation of the thumb, obtain standard anteroposterior, lateral, and oblique radiographs to exclude metacarpal fractures and gamekeeper's fractures. Examples of an anteroposterior and lateral radiograph of a gamekeeper's thumb, respectively, are shown below.

Anteroposterior radiograph displaying a gamekeeper Anteroposterior radiograph displaying a gamekeeper's fracture.
Lateral radiograph displaying a gamekeeper's fract Lateral radiograph displaying a gamekeeper's fracture.

Small, nondisplaced avulsion fractures that are associated with rupture of the insertion point of the UCL are not contraindications to manipulation. If displacement of these fractures did not take place at the time of injury and greatest stress, it is believed that they are stable enough for the manipulation of stress testing.

Three millimeters of volar subluxation of the phalanx on the metacarpal is suggestive of complete UCL rupture and instability.

Instability is also indicated in cases in which there is a radial deviation of >40º in extension and >20º in flexion.

Stress radiographs: Radiographs obtained with the thumb in the flexed and extended positions and with valgus stress at the MCP joint can help the physician to determine the degree of instability of partial tears of the UCL (see the following image).

Radiographic stress test view of the thumb, showin Radiographic stress test view of the thumb, showing an ulnar collateral ligament tear.

Other imaging modalities

Arthrography, ultrasound, and magnetic resonance imaging (MRI) have been used to identify complete tears; however, these tests are not particularly cost effective.[8, 9, 3, 10, 11] Careful stress examination is still the optimal method for determining ligament integrity.

A study used magnetic resonance imaging to investigate the degree of UCL displacement in order to create a simple classification to aid in determining which UCL injuries require surgery. The study concluded that tears of the UCL with more than 3 mm of displacement are likely to require operative repair even in the absence of a true Stener lesion since 90% of these cases failed treatment with immobilization alone.[12]

A systematic review and meta-analysis reported the sensitivities of physical examination, ultrasonography, and MRI for ruling out UCL tears as 97%, 96%, and 99% respectively. MRI and ultrasonography had high specificity for confirming suspected UCL tears (100% and 91%, respectively).  However, MRI had significantly higher specificity (92%) than ultrasonography (72%) for identifying displaced UCL tears.[13]


Stress testing under local anesthesia (see the following 2 images)

Ulnar collateral ligament stress test in full exte Ulnar collateral ligament stress test in full extension.
Ulnar collateral ligament stress test in a flexed Ulnar collateral ligament stress test in a flexed position to isolate the proper portion of the ligament.

The patient often has considerable pain in the thumb; stressing the MCP joint leads to patient guarding and, thus, misleading findings on examination.

The thumb is best examined under local anesthesia, which can be administered in the emergency department (ED) or office setting. Often, 2-3 mL of 1% lidocaine administered into the MCP joint of the thumb is sufficient to relieve the pain and relax the patient's guarding.

If more anesthesia is required, perform a metacarpal or digital block. Some authors recommend the use of an ulnar or median nerve block to negate the effects of the intrinsic muscles. If the injection into the joint relieves the pain, no further anesthesia is necessary.



Acute Phase

Medical Issues/Complications

Complications include the following:

  • Delayed repair of the UCL

    • Complete ruptures of the UCL require surgical intervention for repair within the first 3 weeks of the injury (preferably in the first week while the anatomic position is maintained).

    • Complete tears that are repaired after 3 weeks have an increased incidence of weakness and pain on pinch grasp. An associated increase in MCP joint arthritis is noted in the long term.

  • Closed treatment of a completely torn UCL

    • A 50% failure rate is reported with complete tears that are treated with bracing and early motion. If a patient is unable to tolerate or refuses surgery, then bracing is the treatment of choice. A thumb spica splint or functional brace can be attempted, but it must be understood that full stability of the thumb may not occur.

    • Soft-tissue interposition, which is caused by the adductor aponeurosis holding the torn UCL in a displaced position, prevents healing. Surgical correction is necessary to reconstruct the UCL and allow healing.

    • ROM is limited in the thumb at the MCP joint if the joint is immobilized longer than 4 weeks.

Surgical Intervention

All complete UCL tears require operative intervention. An incision is made over the ulnar border of the MCP joint of the thumb. The adductor aponeurosis is incised longitudinally and retracted distally. The dorsal capsule is then exposed, and the proper and accessory collateral ligaments are assessed. If the joint is subluxed and if the soft-tissue repair seems insufficient to hold the reduced joint, a small-gauge Kirschner wire (ie, K-wire) can be inserted to maintain the MCP joint in position. The UCL can then be repaired. If a small piece of avulsed bone is present, remove it; a large bone fragment should be reduced and preserved.

Other Treatment

For small, nondisplaced avulsion fractures of the proximal phalanx that are found to be stable on stress testing, nonoperative treatment by a spica-type cast for 4 weeks can be completed with good results.

  • Closed treatment

    • Nonoperative treatment can be considered for partial tears (grade I or grade II) of the UCL, which usually involve an isolated rupture of the proper collateral portion of the ligament. This may be treated with immobilization in a thumb spica-type cast for 4 weeks. The cast should be well-molded around the MCP joint, and the interphalangeal joint can be left free. With appropriate closed treatment, expect 90% good to excellent results.[14]

    • Nonoperative treatment can also be considered in patients that either refuse surgery or who are too infirm to tolerate an operative procedure despite a complete UCL tear. In these patients a functional brace or well-molded spica splint can be applied,[14, 15] but it must be understood by the patient that complete healing of the UCL is not expected if the tear was complete.

Recovery Phase

Rehabilitation Program

Physical Therapy

Postoperatively, the patient is immobilized in a thumb spica cast for 4 weeks. At 4 weeks, the cast and any pins that were placed may be removed. The patient is then placed in a hand-based splint that immobilizes the MCP joint for 2 weeks. The splint is removed for therapy during this 2-week period, and active motion of the MCP joint is begun. Unrestricted usage is allowed at 3 months.

Medical Issues/Complications

Complications include the following:

  • Radial sensory nerve injury

    • Even when the radial sensory nerve is isolated and protected during surgery, a neuropraxia may still occur.

    • The neuropraxia usually resolves spontaneously. Only if the neuropraxia persists after 6 months to 1 year should surgical re-exploration be considered.

  • Postsurgical stiffness of the MCP and interphalangeal joints is a common complication (although it is usually not a functional problem) and tends to improve with time.

Maintenance Phase

Medical Issues/Complications

Complications include the following:

  • Chronic instability is a long-term complication of UCL rupture.

    • The most common cause is the patient's failure to seek medical attention in a timely fashion for diagnosis and treatment.

    • The longer a complete rupture of the UCL exists, the more likely it is to progress to chronic instability, even after its repair. Success has been limited with repairing the tissues after 6 weeks from the time of injury.

  • The dorsal capsule, as well as the extensor pollicis brevis and extensor pollicis longus muscles, become attenuated, adding to the dorsal instability of the MCP joint. The thumb then tends to displace volarly and to rotate into supination.

Surgical Intervention

Chronic instability is difficult to treat. Limited success has been associated with repair of gamekeeper's thumb injuries using the capsuloligamentous structures on the ulnar border of the MCP joint.

  • If no degenerative changes are present at the MCP joint, consider a ligament reconstruction. A free tendon, usually the palmaris longus, can be woven through the metacarpal neck and the base of the proximal phalanx.

  • If arthritis is present or if the patient is a manual laborer, consider an arthrodesis of the MCP joint. Arthrodesis does not lead to significant impairment, if motion of the interphalangeal and carpometacarpal joints is maintained.

Return to Play

After surgical repair, the MCP joint is immobilized in a cast for 4 weeks. After this period, the cast is removed and replaced with a removable thumb spica splint so that MCP motion can begin. This is continued for 2 weeks; then the splint is removed completely so the MCP joint can be fully mobilized. Unrestricted usage and return to sports can begin at 3 months.

Patients are not recommended to return to sports that may stress the hand before 3 months have passed. Premature return to full activity can stress the repair or reconstruction and cause chronic joint instability, which is then very difficult to treat. Chronic pain and degeneration can then develop at the MCP joint of the thumb.


Currently, there are no proven accessories for the prevention of gamekeeper's thumb injuries. Ski gloves are being designed to protect the thumbs during skiing, but these have not yet been proven effective.



Medication Summary

Nonsteroidal anti-inflammatory drugs (NSAIDs), which decrease pain and swelling, are the drugs of choice (DOC) in the acute phase of a gamekeeper's thumb injury. The anti-inflammatory effects decrease the acute swelling that is associated with this condition, allowing for a better examination at follow-up (if necessary).

NSAIDs are nonopioid analgesics that are made up of different compounds but classed together based solely on their clinical effects. They typically work by inhibiting the formation of prostaglandins through the cyclooxygenase pathway. NSAIDs do not promote dependence like the opioid agents, but they can be associated with renal, liver, and gastrointestinal (GI) toxicities.

Nonsteroidal anti-inflammatory drugs (NSAIDs)

Class Summary

Pain control and anti-inflammatory effects are essential to the quality of patient care. They are beneficial to patients who have a painful injury.

Ibuprofen (Ibuprin, Advil, Motrin)

DOC for mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.

Naproxen (Anaprox, Naprelan, Naprosyn)

For relief of mild to moderate pain; inhibits inflammatory reactions and pain by decreasing the activity of cyclooxygenase, which is responsible for prostaglandin synthesis.

Cyclooxygenase-2 (COX-2) inhibitors

Class Summary

Although increased cost can be a negative factor in the use of COX-2 inhibitors, the incidence of costly and potentially fatal GI bleeds is clearly less with COX-2 inhibitors than with traditional NSAIDs. Ongoing analysis of the cost avoidance of GI bleeds will further define the populations that will find these agents the most beneficial.

Celecoxib (Celebrex)

Celecoxib inhibits primarily COX-2. COX-2 is considered an inducible isoenzyme, induced during pain and inflammatory stimuli. Inhibition of COX-1 may contribute to NSAID GI toxicity. At therapeutic concentrations, the COX-1 isoenzyme is not inhibited, thus GI toxicity may be decreased. Seek the lowest dose of celecoxib for each patient.