Skier's Thumb Clinical Presentation

Updated: Sep 15, 2019
  • Author: Patrick M Foye, MD; Chief Editor: Sherwin SW Ho, MD  more...
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Presentation

History

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  • Patients with skier's thumb often describe jamming their thumb, either during a fall or with an object such as a ski pole or ball.

  • Pain is reported along the ulnar side of the MCP joint.

  • In cases of UCL laxity, patients often report weakness in their grasping or pinching ability; patients with UCL tears may report inability to perform these movements.

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Physical

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  • Inspection and palpation of a skier's thumb

    • Examination of the injured thumb may reveal swelling at the MCP joint, as well as discoloration and tenderness to palpation along the ulnar aspect. Marked swelling and ecchymosis are suggestive of severe UCL damage. Practitioners should also be aware that swelling and ecchymosis can be indicative of a sesamoid fracture, as this is a commonly overlooked cause of UCL instability.  [7]

    • Sometimes a lump at the ulnar aspect of the metacarpophalangeal joint is indicative of a Stener lesion and suggests a rupture of the ulnar collateral ligament. [8]

    • The location at which the patient has maximal tenderness indicates the site of the ligament injury. Most UCL tears occur distally, near the insertion of the ligament into the proximal phalanx, but proximal rupture also occurs (near the origin on the metacarpal head).

  • Strength

    • The patient's pinch may be markedly weakened, and the thumb may deviate radially.

  • Stress testing

    • In traumatic cases, to avoid inadvertent displacement of the involved bone, stress testing should not be performed until radiographs have ruled out the presence of an undisplaced fracture (see the image below).

      Radiograph displaying a stress test of a torn ulna Radiograph displaying a stress test of a torn ulnar collateral ligament.
    • To appreciate any instability of the MCP joint, a radially directed force is applied to the thumb whose mobility is compared with that of the uninjured hand. There are varying opinions regarding the proper thumb positioning during stress testing. Although the preferred technique is to examine the thumb in full extension, a complete evaluation of the UCL should also include assessment of the thumb in full flexion (when the ligament is maximally taut) (see the images below).

      Stress testing of the metacarpophalangeal joint of Stress testing of the metacarpophalangeal joint of the thumb in flexion.
      Stress testing of the metacarpophalangeal joint of Stress testing of the metacarpophalangeal joint of the thumb in extension.
    • Local anesthetic can be injected into the joint if provocative maneuvering proves to be too painful. If the stress-induced angulation of the injured thumb demonstrates an instability that differs by greater than 30° relative to the uninjured thumb, it can be assumed that the UCL is completely ruptured. [9] In cases in which the UCL insufficiency is a result of chronic damage, patients may be minimally symptomatic but demonstrate UCL laxity during stress testing. UCL injuries of the thumb can be misdiagnosed or the severity underestimated in part because assessment of the injury is limited by patient discomfort. The infiltration of local anesthetic around the injury site can make the physical examination more tolerable for the patient and enable the physician to make a more accurate diagnosis. This simple technique may be a useful adjunct to the standard physical examination.

    • A cadaveric study done by Lankachandra et al demonstrated that an iatrogenic Stener lesion could be created inadvertently during physical examination. This complication can occur via thumb supination and 30˚ of flexion of the MCP joint, provided that prior to physical exam there was already a deficiency in the fascia overlying the UCL. [10]

  • Classification

    • Skier's thumb can be classified into 3 grades. Grade 1 is a thumb sprain without instability of the metacarpophalangeal joint. Grade 2 is an incomplete tear with joint laxity. Grade 3 is a complete tear with instability of the joint. [11]

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Causes

Traumatic injuries in cases of skier's thumb occur more often and result more commonly in UCL ruptures. In addition, UCL injuries from chronic repetitive radial stresses typically lead to UCL laxity and thumb instability but without complete UCL rupture.

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