eMedicine Specialties > Sports Medicine > Wrist and Hand

Hand Dislocation: Differential Diagnoses & Workup

Author: Jeff Chan, MD, MS, FACEP, Clinical Instructor, Stanford University; Staff Physician, Department of Emergency Medicine, Regional Medical Center of San Jose
Coauthor(s): Eleby R Washington III, MD, FACS, Associate Professor, Department of Surgery, Division of Orthopedics, Charles R Drew University of Medicine and Science; Igor Boyarsky, DO, Director of Triage, Assistant Professor, Department of Emergency Medicine, King-Drew Medical Center, University of California at Los Angeles
Contributor Information and Disclosures

Updated: Mar 27, 2009

Differential Diagnoses

Carpal Bone Injuries
Gamekeeper's Thumb
Jammed Finger
Phalangeal Fractures
Skier's Thumb
Wrist Dislocation

Other Problems to Be Considered

Chronic deformity
Collateral ligament injury
Mallet finger

Workup

Laboratory Studies

• Laboratory studies are not generally indicated for diagnosing dislocation injuries of the hand.

Imaging Studies

• Radiography
  • Anteroposterior (AP), lateral, and possibly, oblique views of the affected finger (not the whole hand)
  • Postreduction radiographs
  • Stress radiographs (possibly) (see Image 22 or below)
    
    

    
    
    

    

    Radiograph displaying a stress test of a torn ulnar collateral ligament.

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    Radiograph displaying a stress test of a torn ulnar collateral ligament.

    
    

  • Radiographs of the affected finger: These images help to further define the anatomy of the dislocation, rule out associated fractures, and assess the adequacy of reduction. For dorsal dislocations at the PIP joint, the initial radiographs are often postreduction because the athlete, trainer, or coach commonly reduces the dislocation at the scene. If the finger is still dislocated when the radiographs are obtained, the middle phalanx may be hyperextended and often deviated to the ulnar side (see Images 9-10 or below).
    

    

    Acute dorsal proximal interphalangeal joint fracture-dislocation.

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    Acute dorsal proximal interphalangeal joint fracture-dislocation.

    
    

    

    Acute dorsal proximal interphalangeal fracture-dislocation. A concentric reduction could not be maintained in a splint.

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    Acute dorsal proximal interphalangeal fracture-dislocation. A concentric reduction could not be maintained in a splint.

    
    In a volar dislocation, rotation may be noticeable on the lateral view. The head of the proximal phalanx lies in a different plane than the base of the middle phalanx (see Image 3 or below).
    
    

    

    Volar proximal interphalangeal (PIP) joint dislocation.

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    Volar proximal interphalangeal (PIP) joint dislocation.

  • Common fractures to look for
    • Avulsions at the volar base of the middle phalanx (distal phalanx if DIP) from the volar plate may not affect the treatment plan if they are small. Larger fractures at this location make the injury a fracture-dislocation, which may be unstable in extension (see Image 23 or below).
      

      

      Complex unstable fracture of the proximal phalanx.

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      Complex unstable fracture of the proximal phalanx.

    • Avulsions at the dorsal base of the middle phalanx (distal phalanx if DIP) from the extensor tendon should prompt careful testing of extensor function and probably requires splinting in extension. Avoid splinting in hyperextension. Most central slip injuries, however, are soft tissue only.
    • Impacted fractures of the joint surface are often best visualized on a true lateral view, allowing direct comparison of the radial and ulnar articular surfaces.
  • Important points in the radiographic assessment of reduction
    • Congruence of the articular surfaces: The head of the more proximal phalanx should form a U shape that fits symmetrically within the U shape of the base of the more distal phalanx. If the joint space is not equal throughout on both views, this is highly suspicious for persistent subluxation secondary to entrapment of soft-tissue structures within the joint.
    • Absence of rotational deformity: A volar PIP dislocation in which the head of the proximal phalanx buttonholes between the central slip and the lateral band has a rotational component. This can be observed on the lateral view, where the radial and ulnar aspects of each joint surface would be superimposed.
    • Fractures around the MCP and CMC joints: AP, lateral, and oblique views of the entire hand are indicated to rule out fractures around the MCP and CMC joints (see Images 24-26 or below). In the dorsal dislocation patterns, the oblique or lateral view reveals the dorsal prominence of the affected joint. Common fractures to look for are fractures of the metacarpal bases, avulsion type, associated with the CMC dislocation.
      

      

      Displaced fourth and fifth metacarpal fractures, anteroposterior view (same patient in Images 24-28).

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      Displaced fourth and fifth metacarpal fractures, anteroposterior view (same patient in Images 24-28).

      
      

      

      Displaced fourth and fifth metacarpal fractures, lateral view (same patient in Images 24-28).

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      Displaced fourth and fifth metacarpal fractures, lateral view (same patient in Images 24-28).

      
      

      

      Fourth and fifth metacarpal fractures, oblique view (same patient in Images 24-28).

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      Fourth and fifth metacarpal fractures, oblique view (same patient in Images 24-28).

      
      

      

      Fourth and fifth metacarpal fractures after intramedullary pinning, anteroposterior view (same patient in Images 24-28).

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      Fourth and fifth metacarpal fractures after intramedullary pinning, anteroposterior view (same patient in Images 24-28).

      
      

      

      Fourth and fifth metacarpals after intramedullary pinning, lateral view (same patient in Images 24-28).

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      Fourth and fifth metacarpals after intramedullary pinning, lateral view (same patient in Images 24-28).

    • Breuerton view of the MCP joints: The Breuerton view of the MCP joints is taken with the fingers flat on the plate, the metacarpals at 65° of inclination to them and the tube at 15° from the ulnar side of the hand. It demonstrates the MCP bony surface.
    • Modified lateral views: Modified lateral views of the metacarpals are sometimes necessary because little of the shaft or head can be observed on a true lateral radiograph of the hand. To study the index and middle finger, the hand should be pronated 30° from the lateral. To study the ring and small fingers, the hand should be supinated 30° from the lateral.

Procedures

• Dislocations of the DIP joint are almost always reducible with longitudinal traction and gentle manipulation in the direction opposite to the deformity. Irreducible dislocations may occur secondary to soft-tissue entrapment in the joint or if the patient presents more than a few days out from the injury.⁹
• Closed reduction is almost always successful for dorsal PIP dislocations. Volar dislocations are more problematic, especially if the deformity has a rotary component. For all closed reduction maneuvers, be gentle and limit the number of attempts to 2-3. Irreducible dislocations are usually caused by soft-tissue structures (eg, volar plate, collateral ligament, tendons) trapped in the joint; the patient is likely to need referral to a hand surgeon for open reduction.
  • Most dorsal dislocations of the PIP joint can be easily reduced with gentle traction on the finger with the wrist and MCP joints flexed, followed by pressing the base of the middle phalanx in a volar direction while holding the proximal phalanx steady. As noted, the athlete, coach, or trainer usually accomplishes this maneuver. If the reduction is performed immediately after the injury, it can usually be accomplished without anesthesia. If the reduction is delayed, a digital block with 1% lidocaine (without epinephrine) is helpful (see Image 29 or below).

    
    
    

    

    Digital block.

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    Digital block.

    
    

  • Volar PIP dislocations without a rotatory component are usually reducible with gentle traction. Place the wrist in the neutral position, and press dorsally on the base of the middle phalanx and volarly on the proximal phalanx. Although these injuries are usually treatable with closed reduction, they commonly involve an avulsion of the central slip of the extensor tendon.
  • Volar PIP dislocations with a rotatory component are often difficult to reduce by closed means, because the head of the proximal phalanx becomes trapped between the central slip and one of the lateral bands of the extensor mechanism. Sometimes, these injuries can be reduced by placing the MCP and PIP joints in 90° of flexion with the wrist extended, applying traction, and rotating the middle phalanx in the direction opposite to the deformity.
• MCP dislocations most commonly occur dorsally (simple type). Closed reduction is the treatment of choice and is usually accomplished without difficulty, with gentle traction and flexion of the proximal phalanx. This can be facilitated with a local digital nerve block. In those patients in whom the reduction is not obtained after several attempts and displacement or subluxation persists, open reduction is indicated. At the time of operation, the capsule has usually impinged between the 2 bones, preventing reduction. In children, the displacement of the proximal phalanx may be more to the ulnar than the dorsal side, and a shearing type of osteocartilaginous fragment often prevents complete reduction.
• Early dislocations of the metacarpals can be reduced by the following:
  • In early or acute dislocations of the metacarpals, the carpus closed reduction should be attempted and is usually successful. These dislocations occur dorsally, and reduction can be obtained by gentle traction on the finger of the associated metacarpal while pressing dorsally on the CMC joint dislocation through the range from flexion to extension.The closed reduction can be facilitated with local anesthetic hematoma or intra-articular block at the affected area. After the reduction is accomplished, the wrist and CMC joint should be flexed acutely to determine stability. If closed reduction is successful but the reduction is unstable, continued reduction can be attempted in a dorsiflexion cobra-type cast or by percutaneous Kirschner wire (K-wire) fixation.
  • If reduction by closed methods is unsuccessful, open reduction with removal of the soft tissue in the intra-articular space should be accomplished through a dorsal incision, and the metacarpal base articular surfaces should be fixed in appropriate place with Kirschner wires after being levered into the normal relationship with the carpus. In delayed situations in which the metacarpal bases cannot be reduced, repositioning of the metacarpal bases is best accomplished by bony resection of the bases that overlap the carpus pushing the bases into the normal relationship with the carpus.
• To perform a digital block, first cleanse the skin with povidone-iodine solution. Insert a 25-gauge needle near the base of the finger and through its dorsolateral aspect just lateral to the periosteum of the base of the proximal digit. Advance the needle posteriorly to slide just past the base of the phalanx. As the needle is advanced, inject 1 mL of anesthetic while observing for protrusion of the palmar dermis directly opposite the needle path. Another 1 mL of solution is injected as the needle is withdrawn.
  
  This technique should block both the dorsal and volar digital nerve branches. The same technique is repeated on the medial and lateral sides for complete anesthesia of the finger. Do not use lidocaine with epinephrine. The digital arteries are end arteries that can spasm and cause ischemia of the fingertip and, potentially, necrosis. Volumes of 2-4 mL should not be exceeded to avoid mechanical pressure of injected solution into a potentially confined space.

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