Skier's thumb
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Clinically Relevant Anatomy[edit | edit source]
Injury to the ulnar collateral ligament (UCL) at the metacarpophalangeal joint (MCPJ) of the thumb, also known as "skier's thumb," can involve other structures such as the adductor aponeurosis, the accessory collateral ligament, bony structures, tendons, and neurological tissues.[1]
There are two main supporting ligaments traversing the MCPJ of the thumb: the UCL and the radial collateral ligament (RCL). In general, UCL injuries account for 60-90% of ligamentous collateral injuries.[2] The UCL and RCL arise from the medial and lateral tubercles of the metacarpal condyles, respectfully, and insert into the base of the proximal phalanx on their respective sides (Figure 1).[2]
Figure 1. UCL and RCL of the thumb
The movement association with the thumb MCPJ include flexion, extension, rotation, abduction and adduction. The stability of the MCPJ arises from the bony structures of the thumb in the form of a wider, flatter metacarpal head, and soft tissue support. The surrounding soft tissue offers both dynamic and static stability. Dynamic stability is provided by the muscles of the thumb and static stability is supplied by the collateral ligaments.
Mechanism of Injury[edit | edit source]
An acute UCL injury occurs following a sudden, forced abduction movement at the MCP joint, whereas a forced adduction movement would cause injury to the RCL (Figure 2). With regards to skiing, the injury often occurs when a person lands on an outstretched hand while holding a ski pole, which causes forced abduction of the thumb with or without extension (Figure 3). If the injury to the UCL is not treated properly, this can lead to chronic laxity, joint instability, pain, weakness and arthritis in the MCPJ.
Characteristics/Clinical Presentation
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The most common presentation is pain over the ulnar aspect of the MCPJ of the thumb. If the injury is acute there will be bruising and inflammation. There may be tenderness with palpation, which localizes the injury to the ulnar aspect of the thumb where the UCL is lesioned. Patients typically complain of pain and weakness when using a pincer grip. Examples include holding a pen, grasping objects, unscrewing jar lids and turning a key or doorknob. In the instance of a Stener lesion, there may also be a palpable mass proximal to the adductor aponeurosis.
Differential Diagnosis[edit | edit source]
● RCL injury
● Avulsion fracture
● Wrist sprain
● Wrist fracture
● Dislocation of 1st MCP joint
● Chronic instability of the 1st MCP joint
● Lunate dislocation
Complications[edit | edit source]
An acute UCL injury occurs following a sudden, forced abduction movement at the MCP joint, whereas a forced adduction movement would cause injury to the RCL (Figure 2). With regards to skiing, the injury often occurs when a person lands on an outstretched hand while holding a ski pole, which causes forced abduction of the thumb with or without extension (Figure 3). If the injury to the UCL is not treated properly, this can lead to chronic laxity, joint instability, pain, weakness and arthritis in the MCPJ.
Examination[edit | edit source]
Begin looking for deformities with observation of the hand at rest and in flexion. Then test the sensation in the hand followed by active range of motion (AROM). AROM should be followed by passive range of motion (PROM) and resisted movement to assess tendon integrity, if possible. To test the UCL, apply a valgus stress to the thumb in 30 degrees of flexion (Figure 4). This test is referred to as the Valgus Stress Test. A rupture is likely if there is more than 30 degrees of laxity in the injured thumb or 15 degrees more laxity than on the noninjured side. To test the accessory UCL, apply a valgus stress to the thumb in full extension. A rupture is likely if there is more than 30 degrees of laxity in the injured thumb or 15 degrees more laxity than on the noninjured side. When the accessory UCL is still intact a Stener lesion is less likely. If there is any concern about the possibility of fractures to the first metacarpal or proximal phalanx of the thumb, plain radiographs are indicated prior to stress testing of the UCL. It is important to note that pain when examining can cause apprehension with subsequent tensing of surrounding muscles and can lead to a false negative.
Management/Intervention[edit | edit source]
A UCL injury may be managed conservatively or surgically depending on the severity of the injury, location of injury, and the patient’s goals. Chronic instability of the MCPJ can occur if the injury is not managed properly.
Physical Therapy Management
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Nonoperative treatment is reserved for ligament strains, partial tears, low-demand patients and poor-operative candidates, including patients with degenerative MCP joint disease. More specifically, conservative management is appropriate for patients with less than 30 degrees of valgus laxity of extension of the MCPJ, less than 15 degrees difference between sides, and no signs of avulsion fracture on radiographs. Conservative treatment typically starts with some sort of immobilization process. A thumb spica cast, including the wrist, may also be worn until the initial inflammation is resolved, typically within a week. Swelling can be controlled with elevation while supine, and the use of cold compresses as needed.
Once the inflammation has resolved, the patient is advised to start wearing a thermoplastic splint. The thermoplastic splint allows for the patient to begin movement of the interphalangeal joint. Thermoplastic splinting can be used initially for less severe incomplete ligamentous injuries. Wearing a splint will avoid putting radial stress on the thumb and gives the ligament time to heal. The optimal positioning for the splint involves holding the MCPJ in slight flexion with a slight ulnar deviation; the interphalangeal joints should not be immobilized in the splint. The patient should begin supervised hand therapy during the period of immobilization. The splint should be worn at all times, except for therapy sessions, for at least 6 weeks, after which the splint should only be worn during high risk situations, such as manual labor.
Gentle flexion and extension range of motion exercises can begin after about four weeks, with the patient continuing to wear the splint between therapy sessions. After 8 weeks progressive strengthening exercises may begin, but unrestricted activity is not allowed until after 12 weeks. Gripping and pinching activities should not started until 10-12 weeks and should be advanced as tolerated; forceful gripping activities are typically not tolerated until about week 12.
Surgical Management
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Operative management depends on a timely diagnosis of the injury; chronic lesions become more difficult to repair with increased time since injury since remaining tissue becomes attenuated not robust enough to provide adequate support to the joint. There are multiple methods of repair, which can be categorized into dynamic or static.
Dynamic
● Extensor indicis proprius tendon transfer
● Extensor pollicis brevis tendon transfer
● Adductor pollicis brevis tendon transfer
Static
● Figure-of-eight grafting
● Parallel configuration graft
● Triangular configuration with proximal apex graft
● Triangular configuration with distal apex graft
● Dually opposed biotenodesis fixation of tendon graft
● Tendon graft weaves
● Dually opposed suture anchor fixation
● Hybrid technique
Recent Related Research (from Pubmed)[edit | edit source]
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