Finger Dislocation Joint Reduction 

Dislocation of a joint occurs when traumatic forces cause complete loss of continuity between the joint’s 2 articulating surfaces. Subluxation, on the other hand, occurs when the loss of continuity between the joints is only partial. A dislocation may or may not involve a fracture. Dislocations of the finger joints involve either the interphalangeal (IP) joint or the metacarpophalangeal (MCP) joint.

Each IP and MCP joint has 2 collateral ligaments and a volar fibrocartilaginous plate. Joint support is facilitated by these structures as well as the surrounding tendons. Overall, the IP joints are much more secure than the MCP joints because of the IP joints’ bicondylar arrangement and the fact that the collateral ligaments are tight throughout the entire range of motion. The MCP joints, on the other hand, are condyloid joints with additional lateral motion; their collateral ligaments are most taut during flexion only. Dislocation of a digit dorsally necessitates failure of the volar plate. On the other hand, lateral dislocation violates at least one of the collateral ligaments and produces a partial or complete tear in the volar plate.

Forces responsible for inducing a dislocation may include hyperextension, hyperflexion, ulnar or radial stress (typically, lateral dislocations), axial load, or injury caused by direct pressure or crushing.

Dislocations of the distal interphalangeal (DIP) joint of the second through fifth digits are relatively uncommon because of the stability afforded by the DIP joint’s flexor and extensor tendinous attachments.^[1] Of the DIP joint dislocations that do occur, most are dorsal and are in combination with an open fracture.

Dislocations of the proximal interphalangeal (PIP) joint of the second through fifth digits are the most common dislocations within the hand; dorsal dislocations occur most frequently.^{[2, 3, 4]} If the PIP joint was reduced prior to medical evaluation, the dislocation must be identified as volar, dorsal, or lateral, because the resultant splinting (if incorrect) can result in the development of a boutonniere deformity.

Dorsal finger PIP joint dislocations are typically due to a sports-related high-speed force to the distal finger, which, in turn, causes axial stress and hyperextension.^[4] Lateral finger PIP joint dislocations are due to a blow in the radial or ulnar direction; ulnarly directed dislocations are more common than radially directed dislocations. Lateral finger PIP dislocations are often reduced in the field. Volar finger PIP joint dislocations are extremely uncommon.^[4] They occur when a longitudinal blow to a moderately flexed middle phalanx causes disruption of a collateral ligament and partial avulsion of the volar plate. They are nearly always accompanied by an injury to the central slip of the extensor tendons.

Dislocations of the MCP joint of the second through fifth digits are relatively uncommon because of the MCP joint’s ligamentous anatomy and location at the base of the fingers.^[5] They occur primarily from ulnarly and dorsally directed trauma while the MCP is fully extended. Such forces break the volar plate, joint capsule, and at least part of one of the collateral ligaments. They are usually dorsal, and the second and fifth digits are more commonly affected because of their lesser protection from neighboring digits.

Dislocations of the thumb IP joint are rare because of the significant stability of the IP joint. Thumb IP joint dislocations are usually dorsal and usually occur in association with a fracture. They may be associated with a rupture of the flexor pollicis longus. Dislocations of the thumb MCP joint are primarily dorsal and caused by hyperextension forces.

Reduction of a finger dislocation is indicated if the joint space is partially or completely disrupted with or without an open wound.

Consult with a hand surgeon early in the presence of the following conditions to determine if management should be primarily surgical without reduction attempt:

• Digital neurovascular compromise
• Associated fracture
• Open joint dislocation
• Ligamentous or volar plate rupture
• Joint instability^[6]
• Inability to reduce the dislocation^{[7, 8]}

A digital block (or, possibly, wrist block) should be performed prior to any attempts at reduction.

Digital block

• Each finger is supplied by 2 sets of nerves (dorsal and palmar digital).
• These nerves originate from the deep volar branches of the ulnar and median nerves.
• The palmar digital nerves run alongside the phalanx at the 4-o’clock and 8-o'clock positions, supplying the volar aspect of the digit.
• The dorsal digital nerves run alongside the phalanx at the 2-o’clock and 10-o'clock positions. The palmar digital nerves of the second through fourth digits additionally supply the dorsal distal aspect of the finger, including the fingertip and nail bed.

Wrist block

• A regional partial wrist block (ie, block of the nerve that supplies sensation to the affected finger) may be considered.
• A wrist block provides a larger area of anesthesia than is required for a simple finger dislocation.

Anesthetic equipment

• Lidocaine (without epinephrine for digital blocks)
• Syringes
• Needles (25-27 gauge)
• Alcohol
• Povidone iodine solution (eg, Betadine)

Splinting material

• Padding for under the cast (eg, Webril)
• Preformed splinting material (eg, plaster of Paris)
• Tape
• Scissors
• Bucket
• Warm water
• Aluminum digital splints

Tests for joint stability are mandatory before attempting reduction and following a successful reduction.

Perform a full neurovascular examination.

Perform a digital or wrist block.

Perform an active evaluation of joint stability. Have the patient actively range the affected digit through its full range of motion. If the patient can demonstrate full range of motion without displacement, joint stability is sufficient.

Perform a passive evaluation of joint stability. Have the patient place the affected finger in full extension. Place mild radial and ulnar stress to each collateral ligament. Place volarly directed stress to gauge volar plate stability. Repeat radial, ulnar, and volarly directed stresses with the affected finger in moderate flexion, as well. If displacement does not occur during this evaluation, joint stability is sufficient.

Plain radiographs should be obtained prior to undertaking reduction (to exclude a concomitant fracture) and again following efforts to reduce the dislocation or subluxation. When a dislocation or subluxation is identified on radiograph, it is described according to the location of the distal segment relative to the proximal segment.

See the images below.

Dislocations of finger (second through fifth digits) distal interphalangeal (DIP) joints

Apply gentle longitudinal traction with hyperextension (if dislocation is dorsal) or hyperflexion (if dislocation is volar) followed by pressure to the base of the distal phalanx in the direction that realigns the phalanges.

Splint a volar dislocation without a tendon injury by applying a dorsal splint in mild flexion. To splint a dorsal dislocation without a tendon injury, use a dorsal splint in extension.

See the image below.

If unable to sufficiently reduce the finger, consult a hand surgeon.

Dislocations of finger (second through fifth digits) proximal interphalangeal (PIP) joints

Dorsal finger PIP joint dislocations

Apply longitudinal traction with hyperextension followed by pressure to the dorsal aspect of the base of the middle phalanx as the finger is brought into flexion.

Apply a dorsal splint with 20-30° of flexion.

If an associated fracture of the volar lip affects more than 33% of the joint surface, a closed reduction will be unstable and operative repair is necessary because the collateral ligament is attached to the bony fragment.

Lateral finger PIP joint dislocations

Apply longitudinal traction and ulnar or radial stress to the finger, depending on the initial direction of injury.

Partial tears can be buddy taped; reduced dislocations (ie, complete tears) should be splinted.

Volar finger PIP joint dislocations

Apply mild traction with the PIP and MCP joints flexed.

Splint only the PIP joint in full extension.

See the image below.

Some argue that all volar PIP joint dislocations should be reduced in the operating room, since entrapment of the lateral band around the head of the proximal phalanx may block reduction.^[4]

Strongly consider consultation with a hand surgeon prior to intervention.

Dislocations of finger (second through fifth digits) metacarpophalangeal (MCP) joints

Simple dorsal finger MCP joint dislocations (ie, subluxation)

On examination, the MCP joint is hyperextended 60-90°, but the articular surfaces are in contact without irregular soft tissue.

On radiograph, joint surfaces are in close contact.

This injury can be reduced nonoperatively. Flex the wrist (thereby relaxing the flexor tendons). Hyperextend the affected digit and place pressure over the dorsum of the proximal phalanx in a distal and volar direction. Avoid excessive hyperextension or longitudinal traction, which can convert a simple dislocation to a complex dislocation. Splint in flexion; some argue that buddy taping is sufficient.^[5]

Complex (complete) dorsal finger MCP joint dislocations

On examination, the MCP joint is hyperextended and angulated, the metacarpal head is more noticeable in the palm, and the palmar skin is dimpled.

On radiograph, joint surfaces are separated and a sesamoid bone may be seen within the joint space (pathognomonic of a complex MCP joint dislocation).

This injury must be reduced operatively because the volar plate has been displaced into the MCP joint.

Volar, lateral, and complex dorsal MCP joint dislocations of the finger must be evaluated and treated by a hand surgeon. A mild compression dressing with gentle plaster reinforcement is placed temporarily until the patient can be evaluated by a hand surgeon.

Dislocations of thumb interphalangeal (IP) joints

To reduce this injury, flex the IP joint with continued traction.

Apply direct pressure to the base of the distal phalanx.

Stabilize with a thumb spica splint.

Dislocations of thumb MCP joints

Simple dorsal thumb MCP joint dislocations (ie, subluxation)

On examination, no soft tissue swelling is evident and the MCP joint is hyperextended, but the articular surfaces remain in contact.

On radiograph, the joint surfaces are in close contact.

This injury can be reduced nonoperatively. Provide adequate anesthesia. Grasp the patient’s thumb firmly. Hyperextend the dislocated proximal phalanx. Push the base of the proximal phalanx in a volar direction. Flex the thumb to relax the flexor pollicis longus. Using traction alone may convert a simple MCP dislocation to a complex dislocation. Stabilize the reduced injury in a thumb spica splint with the MCP joint in 20° of flexion.

Complex (complete) dorsal thumb MCP joint dislocations

On examination, the MCP joint is hyperextended and angulated, and the metacarpal head is more noticeable in the thenar eminence with skin dimpling. On radiograph, the joint surfaces are separated and a sesamoid bone may be seen within the joint space (pathognomonic of a complex MCP joint dislocation). This injury must be reduced operatively because the volar plate has been displaced into the MCP joint.

Volar thumb MCP joint dislocations

Apply a dorsally directed force to the volar base of the proximal phalanx. Splint the MCP joint in full extension.

Any thumb MCP joint dislocation associated with a complete rupture of the ulnar collateral ligament requires surgery. (This injury renders the patient’s pinch weak and unstable). If the dislocation is not reduced or if the reduction is not successful, place a mild compression dressing with gentle plaster reinforcement and refer the patient to a hand surgeon urgently.

• Time is of the essence in dislocations. Delay in reduction may lead to swelling and muscle spasm, which make the reduction more challenging.
• Obtain a full history, including age, past medical history, hand dominance, prior hand injuries or issues, occupation, mechanism and time of injury, hand position during the injury, and interventions made prior to presentation.^[9]
• Adequate anesthesia is key to a successful reduction.
• Following reduction, joint stability must be checked and postreduction films must be obtained.
• Some dislocations require operative reduction because of the location of the volar plate, ligaments, or tendons following the injury.
• If reduction is unsuccessful after numerous attempts or if the reduction is not acute, consult with a hand surgeon for possible open reduction and internal fixation.
• With any type of dislocation, all patients should be urgently re-evaluated by a hand surgeon.
• The most common causes of inability to reduce a dislocation are an avulsion fracture involving the joint, a trapped tendon, a buttonhole tear through the volar plate, and significant swelling.^[3]
• If a laceration is associated with a dislocation, copious irrigation and laceration repair should precede splinting.
• Splinting should not exceed 3 weeks.
• Antibiotics and tetanus prophylaxis should be given in the case of an open fracture.

• Inadequate or delayed reduction (joint instability, joint stiffness, joint deformity)
• Overaggressive attempts at reduction (fracture)
• Inadequate immobilization (redislocation)
• Prolonged immobilization (muscle contracture)
• Infection (if open fracture exists)