Reduction of Thumb Dislocation Technique

Updated: Apr 13, 2017
  • Author: Moira Davenport, MD; Chief Editor: Erik D Schraga, MD  more...
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Technique

Approach Considerations

Keep the metacarpophalangeal (MCP) joint in flexion and adduction while attempting the reduction. This may aid the effort by relaxing the intrinsic muscles of the thenar eminence as well as the flexor pollicis longus. Do not apply longitudinal traction on an MCP dislocation.

If the attempted reduction is not successful, do not make multiple repeat attempts. The volar plate, a tendon (eg, flexor pollicis longus or flexor pollicis brevis), or a sesamoid bone may be entrapped within the anatomic joint space, and reduction will be impossible without surgery. [13]  Seek orthopedic consultation to schedule such a procedure.

Adequate closed reduction may be more difficult or impossible to achieve in the following circumstances:

  • Patients who present several hours or days after the injury
  • Patients with remarkable soft-tissue swelling around the injury
  • Patients with residual joint instability after reduction
  • Patients who lose reduction after it is initially achieved
  • Radiographs that show a sesamoid bone lodged in the anatomic joint space
  • Dimpling over the thenar eminence from entrapment of the metacarpal head

Steps that may improve chances of successful reduction include the following:

  • Ensuring adequate analgesia
  • Using a low-dose anxiolytic, such as a short-acting benzodiazepine
  • Repositioning the patient or the physician's hand placements

Avoid increasing the strength of forces applied to the reduction attempt; this increases the potential for additional injury.

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Thumb Joint Reduction

Reduction of dorsal dislocation

Apply appropriate forces to the injury while maintaining the established position of hyperextension, as follows.

When reducing a dorsal interphalangeal (IP) joint dislocation, apply longitudinal traction on the thumb with the hand grasping the distal phalanx. Apply simultaneous distal pressure on the dorsal base of the distal phalanx. Use your nondominant hand to hold the patient. (See the image below.)

Position of hyperextension used for reduction of d Position of hyperextension used for reduction of dorsal interphalangeal (IP) joint dislocation.

When reducing a dorsal MCP dislocation, do not apply initial traction on the MCP joint; doing so would increase the chance of entrapping another structure in the anatomic joint space, making reduction impossible. Instead, with your nondominant hand, apply only distal pressure to the dorsal base of the proximal phalanx. (See the image below.)

Position of hyperextension used for reduction of d Position of hyperextension used for reduction of dorsal metacarpophalangeal (MCP) joint dislocation.

While the above forces are being applied, bring the injured joint into a position of flexion. The act of joint flexion while applying the maneuvers described above reduces the dislocation, thus resolving the injured joint’s deformity and restoring range of motion.

Reduction of volar dislocation

The joint is initially held in extreme flexion rather than hyperextension, thus exaggerating the injury.

Apply distal pressure either on the volar base of the distal phalanx (for IP dislocations) or on the proximal phalanx (for MCP dislocations). Achieve reduction by moving the dislocated joint into a position of relative extension without hyperextending the joint.

Reduction of volar MCP and IP dislocations of the thumb is less successful and leads to more complications than reduction of dorsal dislocations does. [14]

Special considerations

Stener lesion is a potential first MCP injury that would cause a reduction attempt to be unstable without operative management. [15]  This type of MCP dislocation may appear identical to normal dislocations on radiographs but is complicated by a complete tear (third-degree sprain) of the ulnar collateral ligament (UCL) with displacement of the ruptured ligamentous fragment proximal to the adductor aponeurosis.

A Stener lesion can be signaled by the following findings:

  • Marked laxity in the relocated MCP joint when valgus pressure is applied (see the image below)
  • A mass near the ulnar side of the metacarpal head that represents the displaced ligament
  • A small avulsion fracture at the UCL insertion to the metacarpal head
  • An MCP reduction that dislocates again with minimal force
Hand position used for testing if laxity is presen Hand position used for testing if laxity is present with valgus strain of metacarpophalangeal (MCP) joint. Such laxity suggests presence of ulnar collateral ligament (UCL) tear and indicates possible existence of Stener lesion.

If a Stener lesion is suspected, immobilize the injury in a short-arm thumb spica splint, and consult an orthopedist with the goal of scheduling surgical repair of the UCL within 10 days of the injury. This injury does not heal without surgical intervention.

Patients who present with a mechanism of injury that suggests a large axial load on the thumb are more likely to have a Bennett or Rolando fracture. Particularly careful radiographic exclusion of these fractures is indicated in these patients.

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Postprocedural Care

Repeat and document a complete neurovascular examination to evaluate postreduction changes in the thumb’s perfusion, sensation, and strength. Then, carefully assess and document the postreduction range of motion and stability of the injured joint.

After reducing an MCP dislocation, assess the MCP joint’s collateral ligaments by applying gentle varus/valgus pressure to the injured thumb’s proximal phalanx with the MCP joint held in flexion and documenting any joint laxity indicative of ligament rupture. Ulnar collateral ligament (UCL) rupture or gamekeeper thumb, also known as skier thumb, is of particular clinical importance in that it may indicate the presence of a Stener lesion (see Thumb Joint Reduction). 

If a stable reduction has not been achieved, repeat attempts may be performed; however, if the above maneuvers have been unsuccessful even when performed under optimal conditions, closed reduction should be considered impossible.

Obtain postreduction radiographs to determine and document the adequacy of reduction and reexamine for occult fractures. Radiographs should be taken even when reduction was not believed to be successful.

Apply a short arm thumb spica cast, using at least eight layers of 3-in. plaster roll. The splint should extend from the distal IP joint of the thumb to the midforearm. The distal tip of the distal phalanx of the thumb should be left exposed for serial neurovascular examination.

The splint should hold the extremity with the wrist in 20-30º of extension and the hand in wine-glass position.

Give the patient the following instructions regarding the splint:

  • Keep the splint clean and dry; if it becomes wet, dirty, or damaged, promptly return to the emergency department for a new one
  • Wear the splint at all times
  • Avoid mechanical stress to the splint for the first 24 hours after application to allow the plaster of the splint to harden
  • To shower, seal a plastic bag or wrap around the splint and hold the extremity out of the shower at all times
  • If pain, numbness, tingling, or discoloration of the extremities distal to the splint is noticed, immediately proceed to the closest available emergency department or medical practitioner for emergency evaluation
  • Wear this splint for the next 6 weeks to allow the structures of the injured joint to heal properly

A follow-up appointment should be arranged with a hand surgeon or orthopedist for approximately 1 week after the reduction attempt.

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Complications

Reduction attempts, particularly if performed repeatedly and with large amounts of force, may cause neurovascular injury to the digit. This can be quickly detected by careful reexamination after each reduction attempt. If such a neurovascular injury occurs, emergency consultation with an orthopedist or hand surgeon is paramount. Surgical intervention may be the only option to reverse such an injury.

Fracture of the first metacarpal, the proximal phalanx, or the distal phalanx may occur with forceful reduction attempts. Although this is a rare occurrence, physicians should search for new fractures on postreduction radiographs, as such fractures may add a new aspect of instability to the injury.

Closed reduction may not provide adequate reduction of some Bennett fractures; the flexor pollicus longus tendon or digital nerve may block complete reduction. [16]  Open reduction and internal fixation (ORIF) may be required. [17]

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