Finger dislocations in general are relatively simple to identify and treat, but ligament, tendon, or volar plate injuries are often missed. Thumb dislocations can present with or without lacerations, and are often associated with ligamentous injuries. An injured thumb is almost always treated with splinting. Follow-up for these injuries is crucial. Radiographs are useful in locating the areas of injury and identifying avulsion fractures.
Thumb dislocation in a 24-year-old man 12 hours after injury.
Listen to the patient's story to identify the mechanism by which the injury occurred because mimicking this mechanism is typically the best way to relocate the joint. Patients typically do not need local anesthesia or digital block because relocation techniques are quick and can often be done while simply distracting the patient. Treatment is dependent on your skill level, comfort, and ability to recognize these injuries.
Keep in mind that the thumb contributes to 40 percent of hand function. Preservation of its ligament and tendon function is extremely important. Remember that the extensor or flexor pollicis longus and brevis tendons assist with thumb flexion/extension. If only one of these tendons is injured, the alternative extensor or flexor tendon will still allow the patient to extend or flex the thumb.
If the ulnar collateral ligament is injured, the patient will have a weak grip. This ligament connects the metacarpophalangeal (MCP) joints to the proximal phalanx of the thumb. These will also need close follow-up and splinting for several weeks.
All significant thumb injuries, even those with no obvious fracture or ligamentous disruption should be splinted for five to seven days. A thumb spica splint is the most common technique to immobilize the thumb.
Thumb Anatomy Review
-Flexion: Flexor pollicis longus and brevis as well as opponens pollicis and adductor pollicis
-Extension: Abductor pollicis longus and brevis as well as extensor pollicis longus and brevis
-Adduction: Adductor pollicis longus
-Abduction: Abductor pollicis longus and brevis as well as extensors
A diagram demonstrating the hand's anatomy. (Source: CreativeCommons.org)
-Digital blocks or local infiltration if indicated
-Pre-reduction radiographs are routine.
-Longitudinal traction method of joint reduction
-Laceration repair if indicated
-Immobilization with thumb spica splint
-Follow up with hand specialist within one week.
Thumb dislocation (metacarpal phalangeal joint) with radiograph evidence of fracture-dislocation of the left thumb.
-Order appropriate radiographs of the finger, not just of the hand, after examining the patient. Appropriate views include the AP, lateral, and oblique views. Lateral views of the finger allow the provider to see subtle dislocations or avulsion fractures.
-Digital blocks are not routine, but do one as needed or if the patient has a laceration, needs extensive wound care, or could benefit from a block. Note: Skin repairs are done after the dislocation is reduced.
-Longitudinal traction method of joint reduction is used to treat the injury.
-Distract the patient with conversation while holding the injured area. It helps to make eye contact.
-Mimic the path by which the initial injury occurred, slightly exaggerating the deformity that is present.
-Pull the finger forcefully and quickly in the opposite direction as you push the joint back into position.
-Complete a full range-of-motion exam and neurovascular check. Check stability.
-Perform appropriate splinting. Thumb spica is recommended for this injury.
-Orthopedic or hand specialist consultation is recommended within one week of the injury.
-Ask the patient about tetanus vaccination if there is a laceration or abrasion.
-Oral NSAIDs are appropriate treatment for pain and swelling.