Ulnar Collateral Ligament Injury

Article Author:
Michael Mohseni
Article Editor:
Charles Graham
Updated:
9/29/2019 9:10:16 PM
PubMed Link:
Ulnar Collateral Ligament Injury

Introduction

Ulnar collateral ligament injury of the thumb originally derived its name as gamekeepers' thumb from those gamekeepers who would develop the injury as a result of repetitively twisting and breaking of the neck of small game such as birds and rabbits.[1] This action would mechanically lead to degeneration and tears of the ulnar collateral ligament of the first metacarpophalangeal joint. Presently, the injury is also referred to as skiers’ thumb given that this more commonly seen as the cause of this injury.[2]

Etiology

Any injury causing extreme thumb abduction can result in ulnar collateral ligament injury. In skiers, when the thumb strikes a fixed ski pole there is forced abduction along with hyperextension of the first metacarpophalangeal joint.[2] The ulnar collateral ligament acts to stabilize the thumb at its base; if a patient falls or has the thumb forcefully abducted the ulnar collateral ligament can be injured. Trauma from repetitive abduction and hyperextension can cause chronic injury to the ligament as well.

Epidemiology

This injury occurs in skiing accidents (when the thumb is forcefully driven into the ski pole), falls, and other sports-related injuries (e.g., baseball and javelin). The injury pattern occurs more frequently in males (60%) than females (40%).[3]

Pathophysiology

The ulnar collateral ligament acts as a lateral stabilizer of the metacarpophalangeal joint.  In concert with the intrinsic hand and finger muscles, it allows for adequate grasp and pinch mechanism.  Hyperextension abduction mechanisms can result in a partial, complete, or chronic injury to the ulnar collateral ligament.  Swelling and inflammation at the metacarpophalangeal joint along with laxity and instability subsequently ensue.

History and Physical

Patients with an ulnar collateral ligament injury typically complain of pain localized to the first metacarpophalangeal joint. The discomfort is worsened by abduction or hyperextension of the thumb. There may be a complaint of swelling at the base of the thumb, perhaps more pronounced along the ulnar aspect. The patient may present acutely after an injury, but the presentation may also be delayed by weeks given ongoing pain and weakness of the injured thumb. The weakness described by the patient is usually when he or she is attempting to grasp or pinch an object between the index finger and the affected thumb.

Physical examination may be helpful in clinching the diagnosis. Valgus stress testing (thumb abduction) can reveal instability, laxity, or a complete tear of the ulnar collateral ligament. It is useful to compare this abduction stress testing to the unaffected thumb. Partial tears may result in increased mobility (laxity) in comparison to the uninjured side. Complete tears will reveal an obvious lack of endpoint in motion during the abduction stress testing.

When the metacarpophalangeal joint is flexed to 45 degrees, the ulnar collateral ligament is more adequately isolated from the remaining ligamentous stabilizers. Stress testing in this position can also aid in the diagnosis.

Classically, the orthopedic literature states that any laxity greater than 15 to 20 degrees with valgus stress testing (in comparison to the unaffected side) suggests ulnar collateral ligament tear. Absolute laxity of 30 degrees or more also is highly suggestive of a tear. In clinical practice, however, this may be challenging to measure accurately.[4]

Evaluation

X-ray imaging of the thumb should be performed to rule out concomitant bony injury. Bony avulsion injury may be present at the base of the proximal phalanx at the insertion site of the ulnar collateral ligament. In most instances, however, x-ray imaging is normal in patients with an ulnar collateral ligament injury.

Ultrasound can be performed real-time to assess for degree of laxity at the first metacarpophalangeal joint. This can be performed on both thumbs, comparing the degree of ulnar collateral ligament laxity between the injured and uninjured sides.

Magnetic resonance imaging (MRI) has both high sensitivity and specificity for ulnar collateral ligament rupture but is not generally indicated.

Treatment / Management

In the acute phase of ulnar collateral ligament injury, rest, ice, and immobilization should be utilized. Splint immobilization in the acute setting is achieved with a thumb spica splint.

Bony avulsion fractures in association with ulnar collateral ligament injury require urgent referral to a hand specialist. Also, any valgus stress laxity greater than 15 to 20 degrees in compared to the uninjured side (or 30 degrees of absolute laxity) should be referred to a hand surgeon.

Partial tears may do well with splinting only but still need a referral to a hand surgeon. After a period of immobilization for approximately 3 weeks, these nonsurgically managed injuries can begin gentle rehabilitation: passive and active physical therapy, thumb strengthening, and hand strengthening. However, the immobilization should be continued for at least 3 additional weeks while the patient is not actively rehabilitating the thumb and hand. If instability, weakness, pain, and swelling persist, a surgical referral is required.

Complete ulnar collateral ligament tears repaired surgically tend to do well and are mostly without complications. Early repair is recommended for most complete tears to prevent the development of the Stener lesion. Normally, the ulnar collateral ligament lies deep to the adductor pollicis tendon. In a Stener lesion, the torn end of the ulnar collateral ligament slips and becomes superficial to the adductor aponeurosis and muscle. Therefore, with this lesion, the adductor pollicis muscle lies between the ulnar collateral ligament and the metacarpophalangeal joint, preventing appropriate healing.[5]

Differential Diagnosis

The differential for ulnar collateral ligament injury includes, but is not limited to, bony avulsion injury, adductor pollicis tendon injury, metacarpophalangeal dislocation, or chronic arthritic disease of the metacarpophalangeal joint.

Prognosis

Surgery is generally well tolerated in complete tears and outcomes, as stated above, are good. Most partial tears treated with splinting alone also tend to heal without residual pain, laxity, instability, or stiffness.  Patients who develop Stener lesions or who may go undiagnosed for weeks tend to develop metacarpophalangeal arthritic changes. Return to work or sporting activities can occur in approximately 6 weeks.

Pearls and Other Issues

A hyperextension injury causes most ulnar collateral ligament injuries with force abduction of the thumb at the first metacarpophalangeal joint. Skiers’ thumb is synonymous with this injury as it refers to the mechanism by which a downhill skier injures his or her thumb against the ski pole.

Clinically, patients will have increased joint laxity with valgus (abduction) stress testing. Testing should be performed and compared with the unaffected side to help determine if the degree of laxity is abnormal for the patient.

Concomitant fractures should be ruled out in any patient with a suspected ulnar collateral ligament injury. Standard plain films will usually suffice.

Enhancing Healthcare Team Outcomes

Most cases of ulnar collateral injuries require referral to a hand specialist to determine appropriate long-term care options. Acutely, clinicians and nurses should provide pain relief. Ice can be applied to the injury, and a thumb spica splint can be used to help immobilize the thumb's metacarpophalangeal joint. Some tears can be treated with immobilization alone, but complete tears generally require surgery to avoid the Stener lesion and subsequent chronic arthritic changes. Some cases may require the administration of pain medication. Pharmacists should be consulted to assist in pain medication selection and patient education. The nurses should assist with splint placement and patient education. A collaborative interprofessional approach will result in the best outcomes. [Level 5]


References

[1] Gamekeeper's thumb: ulnar collateral ligament injury., Richard JR,, American family physician, 1996 Apr     [PubMed PMID: 8623701]
[2] Skier's thumb., Anderson D,, Australian family physician, 2010 Aug     [PubMed PMID: 20877752]
[3] Ulnar collateral ligament injuries of the thumb: 10 years of surgical experience., Chuter GS,Muwanga CL,Irwin LR,, Injury, 2009 Jun     [PubMed PMID: 19389670]
[4] Injury to ulnar collateral ligament of thumb., Madan SS,Pai DR,Kaur A,Dixit R,, Orthopaedic surgery, 2014 Feb     [PubMed PMID: 24590986]
[5] Management of thumb metacarpophalangeal ulnar collateral ligament injuries., Rhee PC,Jones DB,Kakar S,, The Journal of bone and joint surgery. American volume, 2012 Nov 7     [PubMed PMID: 23138242]