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Physical Examination
On physical examination, the patient’s vital signs are as follows:
• Temperature: The patient is afebrile
• Pulse: 96 beats/min
• Respiration: 20 breaths/min
• Blood pressure: 122/82 mm Hg

The patient is alert and oriented and is not in acute distress. His painful hand is normal in appearance without evidence of swelling, erythema, or breaks in the skin. Palpation of the MCP joint of the right thumb reveals pain on the medial (ulnar) aspect, and there is laxity and pain on valgus testing. The patient has no pain with palpation of the interphalangeal joint or over the anatomic snuffbox. He is neurovascularly intact, with a 2+ radial pulse.

Differential Diagnosis
• Osteomyelitis
• Atypical ossicle joint lesion
• Sesamoid bone fracture
• Transverse fracture
• Scaphoid fracture

Urgent Care Work-Up
A thumb x-ray (Figure 2) was ordered.

Avulsion fracture of the proximal aspect of the proximal phalanx of the thumb caused by gamekeeper’s thumb injury.

A typical mechanism of strain or tear of the ulnar collateral ligament (UCL) of the thumb is by a hyperextension and abduction of the thumb. With severe hyperextension, the UCL can be torn or may avulse bone at the point of approximation at the proximal aspect of the phalanx. The name originated from the fact that gamekeepers developed chronic degeneration of the UCL of the MCP when twisting the necks of fowl (game). A more common mechanism today involves a fall by a skier who is holding a pole, causing the thumb to undergo hyperextension. This is the second most common ski injury, accounting for 17% of all ski injuries, with the most common injury being to the knee. Three-quarters of ski injuries to the thumb involve the UCL.

The bones of the thumb are held in place by collateral ligaments, located on the lateral aspect of each phalanx. With abduction of the thumb and hyperextension, the UCL may be stretched or torn or may avulse a segment of bone from its insertion at the proximal aspect of the proximal phalanx. The most common site of avulsion is with the distal aspect of the UCL (where it attaches to the proximal phalanx). Note that the radial collateral ligament (RCL) may also be injured.

What to Look For
The mechanism of injury is the arguably the most important element of the medical history, with a typical mechanism such as fall while skiing or a similar mechanism of abduction and hyperextension of the thumb increasing the likelihood of the diagnosis of UCL strain or tear. Repetitive strain on the UCL can also cause strain or tear at its insertion sites. Injury to the UCL has been noted in a wide range of sports, including rugby and basketball, and has even been documented after a handshake. Localize the area of greatest pain, typically on the ulnar aspect of the MCP joint. Finally, inquire about pain at the proximal and distal joint.

Initially in the physical examination, assess the appearance for integrity of the skin and possible swelling. Palpate for the area of greatest pain, typically over the ulnar aspect of the MCP joint. Also palpate the radial aspect of the joint, because there may be an associated RCL injury. Examine the proximal and distal joints, including the anatomic snuffbox. Assess the neurovascular status for gross sensation as well as vascular status with documentation of the radial and/or ulna pulse. Check the stability, though this is unlikely to change urgent care management and will likely result in significant pain. However, if there is a way to test joint laxity, placing valgus stress (radial deviation of the MCP joint) may reveal laxity. Note that there are various degrees of laxity in finger joints, so comparison to the opposite side is essential. Assess for laxity in the neutral position and with the MCP joint flexed. Perform stress testing for laxity after x-ray results are available to ensure there is not an avulsion fracture.

A three-view x-ray is typically obtained if there is a strain or tear of the UCL. Assess for avulsion fracture, because the presence of such a fracture may change the decision about conservative management versus surgical repair. With repetitive injury, the x-ray may show degenerative changes. When there is high suspicion for an injury, consider stress views to quantify the degree of UCL laxity, though this will infrequently change management in the urgent care. With UCL rupture, there is frequently an associated bony avulsion.

A thumb spica splint should be applied to immobilize the thumb. This may be a splint that has a hook-and-loop fastener. Patients with an associated fracture are generally referred to an orthopedic surgeon or hand surgeon, though conservative management initially is acceptable.

If conservative management is the initial approach, advise follow-up with the patient’s primary-care physician or an orthopedic or hand surgeon in 5 to 7 days. Indications for conservative management include the following: partial, nondisplaced UCL tears and associated fractures without displacement, which can be handled with 4 to 6 weeks of immobilization in mild flexion and slight ulnar deviation. There is not uniform agreement about when surgery is indicated, but these are some possible indications:
• Fracture displacement
• Significant articular displacement
• Clinical instability
• Fragment rotation

Acknowledgement: Figure 2 is used under a Creative Commons Attribution-Share Alike 3.0 Unported license from James Heilman, MD. Game keepers. In: Wikimedia Commons. Original figure available from Figure 1 is a modified version of Figure 2, with modification allowed under the license.

Painful Metacarpophalangeal Joint After a Skiing Fall