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MCP (MetaCarpophalangeal) Collateral Ligament Sprain

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MCP (MetaCarpophalangeal) Collateral Ligament Sprain
Kathleen Weber
Basics
Description
  • Injury to the collateral ligaments of the metacarpophalangeal (MCP) joints; most commonly the MCP joint of the thumb
  • An injury to the MCP ligament may result in a simple strain to a complete tear of both proper and accessory ligaments (1).
Epidemiology
  • Isolated injuries to collateral ligaments of the MCP joints are uncommon, except for those of the MCP joint of the thumb, which is the focus of this chapter.
  • Ulnar collateral ligament (UCL) injuries of the MCP joint of the thumb (gamekeeper's thumb or skier's thumb) occur more often than radial collateral ligament (RCL) injuries.
  • UCL sprain is the 2nd most common injury encountered by skiers and most common ligamentous injury to the thumb.
  • The ligamentous injury can occur either at the proximal or more commonly the distal attachment of the ligament.
  • ∼50% of these injuries will have an associated base of the proximal phalanx fracture.
  • Acute UCL injury is seen frequently in football players, ball-handling athletes, and other contact sports participants.
Commonly Associated Conditions
  • Complete rupture of the collateral ligament (proper and accessory) and volar plate (2)
  • Stener lesion: The adductor pollicis aponeurosis is interposed between the torn end of the UCL (thumb) and its insertion into the base of the proximal phalanx, inhibiting healing (not seen in RCL complete tears) (2,3).
  • 3 types of avulsion fractures: Small fragment at the base of the proximal phalanx; a large, intraarticular fracture that involves at least 25% of the articular surface of the base of the proximal phalanx; and an avulsion fracture involving the volar plate (2)
  • Dislocation of the thumb MCP joint
Diagnosis
History
  • MCP collateral ligament sprain is most commonly an acute injury related to trauma.
  • Mechanism of injury to the UCL of the MCP joint of the thumb is sudden, forced, radial deviation (abduction) and extension resulting in partial or complete tear of the ligament.
  • Mechanism of injury to the RCL of the MCP joint of the thumb is force adduction or twisting of the flexed joint.
  • Prompt diagnosis is the key to a good outcome.
  • Chronic MCP collateral ligament sprain is usually secondary to a missed diagnosis from an earlier acute injury.
Physical Exam
  • Hallmark symptom of acute UCL injury is pain and swelling localized to the ulnar aspect of the MCP joint along the UCL.
  • Acute injury: Ecchymosis and pain over the ligament
  • Chronic injuries: May not be painful
  • A palpable mass may be present.
  • Weakness of thumb; weakness with pinch noted with UCL injury (1)
  • RCL injuries have pain and swelling localized to the radial aspect of the metacarpal head, and activities such as twisting open a jar lid can exacerbate the symptoms.
  • A careful physical exam differentiates a sprain from a complete tear (2).
  • Always compare with asymptomatic thumb.
  • Examine the joint for swelling, ecchymosis, and areas of tenderness.
  • Anteroposterior (AP) and lateral radiographs should be obtained prior to stressing the joint because a nondisplaced fracture can be displaced as a result of the stress.
  • If radiographs are negative, the stability of the ligament should be tested.
  • Test the ligaments by applying radial stress (UCL) or ulnar stress (RCL) to the MCP joint in full extension and in 30 degrees of flexion.
  • A collateral ligament injury should be suspected if during stress testing a firm endpoint is lacking.

    • P.373


  • Valgus stress of the flexed MCP joint with opening of ≥30 degrees or 15 degrees greater than the contralateral thumb indicates collateral ligament proper complete rupture; <30 degrees of laxity assumes a partial tear (2,4).
  • Valgus stress of the extended MCP joint with opening of ≥30 degrees suggests an accessory collateral ligament tear (2).
  • If unable to make a clear distinction on clinical exam, stress radiographs are indicated.
Diagnostic Tests & Interpretation
Imaging
  • AP and lateral radiographs of the thumb to evaluate for a fracture (2,3)
  • Stress radiographs in full extension and in 30 degrees flexion if no fracture (always compare with the contralateral thumb)
  • Additional radiographic signs that indicate a complete rupture are volar subluxation of the proximal phalanx seen on lateral view and radial deviation of the proximal phalanx seen on AP view.
  • Stress films are contraindicated in children with Salter-Harris fractures.
  • MRI and US may be used to evaluate for a ligament injury and Stener lesion (3,4).
Differential Diagnosis
  • Complete tear of collateral ligament
  • Dislocation of the thumb MCP joint
  • Fracture
Treatment
  • Analgesia (5): NSAIDs, ice
  • Non-thumb-related collateral ligament sprains, depending on severity, can be splinted immobilized or “buddy taped” (2)[C].
  • No detectable instability: Immobilization (thumb spica splint) for 2 wks (6)[C]
  • Partial tear with stable joint: Thumb spica splint or cast for 4–6 wks depending on severity of the injury (2)[C]; thumb is immobilized in slight flexion in the spica cast; the interphalangeal joint is not immobilized to allow active motion and prevent scarring of the extension mechanism.
  • Complete tear: Repair surgically (2)[C].
  • Avulsion fracture: Small avulsions that are not intraarticular can be treated nonoperatively; nondisplaced fractures, thumb spica cast (application as above) for 4–6 wks (2)[C].
  • Avulsion fracture: Rotated, displaced, or large intraarticular fragments require surgical repair (2)[C].
  • Surgical repair is necessary for Stener lesion; failure to recognize this injury or inadequate treatment can result in chronic instability (1)[C].
Additional Treatment
Referral
Prompt referral to an orthopedist or hand surgeon is indicated for all but uncomplicated injuries and when a Stener lesion cannot be ruled out on the basis of physical examination and standard radiographs.
Additional Therapies
  • When the cast is removed, range of motion (ROM) exercises are performed several times a day; a removable splint is worn for an additional 2–3 wks.
  • Sports participation: Protect the thumb for ∼3 mos either by “buddy taping” it in adduction to the index finger or by using a splint.
Surgery/Other Procedures
  • Surgical treatment is recommended for fractures that are displaced, rotated, or have significant articular involvement.
  • Surgical repair is necessary for complete ligament tears and Stener lesions.
  • The goal of surgery is restoration of anatomy and joint stability.
Ongoing Care
Complications
Inadequate treatment of UCL thumb injuries may result in chronic painful instability, weakness of pinch, and arthritis.
References
1. Rettig A, Rettig L, Welsch M. Anatomic reconstruction of thumb metacarpophalangeal joint ulnar collateral ligament using an interference screw docking technique. Tech Hand Up Extrem Surg. 2009;13:7–10.
2. Carlsen BT, Moran SL. Thumb trauma: Bennett fractures, Rolando fractures, and ulnar collateral ligament injuries. J Hand Surg [Am]. 2009;34:945–952.
3. Ebrahim FS, De Maeseneer M, Jager T, et al. US diagnosis of UCL tears of the thumb and stener lesions: technique, pattern-based approach, and differential diagnosis. Radiographics. 2006;26:1007–1020.
4. Papandrea RF, Fowler T. Injury at the Thumb UCL: is there a stener lesion? JHS. 2008;33A:1882–1884.
5. Baskies MA, Lee SK. Evaluation and treatment of injuries of the ulnar collateral ligament of the thumb—metacarpophalangeal joint. Bull NYU Hosp Jt Dis. 2009;67:68–74.
6. Fricker R, Hintermann B. Skier's thumb. Treatment, prevention and recommendations. Sports Med. 1995;19:73–79.
Codes
ICD9
842.12 Sprain of metacarpophalangeal (joint) of hand


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