Interphalangeal (IP) joint dislocations of the fingers and toes are common.[1, 2, 3] Typically associated with forced hyperextension or hyperflexion of the digit, they require immediate reduction. The IP joint is a hinge joint that allows only flexion and extension and consists of several ligamentous complexes. The volar plate provides stability against hyperextension injury and dorsal dislocation of the phalanx. It often ruptures during a dorsal dislocation and may be associated with an avulsion fracture at the base of the phalanx. The strong collateral ligament complex resists hyperextension and lateral dislocation injury. The extensor hood complex stabilizes against hyperflexion injury and volar displacement of the phalanx.
Dislocations of the distal IP (DIP) joint of the fingers are often associated with fracture, tendon rupture, and/or proximal interphalangeal (PIP) joint involvement. Upon axial loading and hyperextension of the fingertip, the volar plate of the DIP joint tears and the joint may be displaced.[4, 5, 6, 7] Forced hyperflexion results in a volar IP joint dislocation (eg, where the distal phalanx is dislocated volar to the middle phalanx).[8]
According to studies, 59.4% of all dislocations involve the joints of the thumb or little finger, with the highest dislocation rates being in the proximal interphalangeal joint of the little finger, the metacarpophalangeal joint of the thumb, and the proximal interphalangeal joint of the ring finger. Dislocations are relatively uncommon in children. Lateral bending forces are more often transmitted through the physis rather than the collateral ligaments in a child‘s hand because the growth plate is the path of least resistance. Although rare, the thumb metacarpophalangeal (MCP) joint is the most commonly dislocated joint in the skeletally immature hand. The PIP joint is the most commonly injured articular surface, involving volar plate or collateral ligament avulsion fractures.[9, 10]
Causes of interphalangeal dislocations include axial compression or lateral forces directed to the digit; forced hyperextension or hyperflexion of the digit from traumatic athletic injury, entrapment of finger between objects, or a fall; and predisposition to ligamentous injury in those with lax ligaments (eg, Down syndrome).
Diagnosis
Take anteroposterior, true lateral, and oblique radiographs of the affected digit. Obtain 3 views prior to and after reduction.
(See the images below.)
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Anteroposterior view of distal interphalangeal (DIP) joint dislocation
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Lateral view of distal interphalangeal (DIP) joint dislocation
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Oblique view of distal interphalangeal (DIP) joint dislocation
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Oblique view of proximal interphalangeal (PIP) joint dislocation
Treatment
Splint, ice, and elevate the affected digit.[11, 12] Neurovascular status should be evaluated before and after transport to the ED. Administer digital block anesthesia 10-15 minutes before any reduction maneuver. Be sure to remove all rings.
With the patient's hand or foot securely braced, grasp the dislocated phalanx with dry gauze loosely wrapped around the phalanx, and hyperextend the joint slightly with gentle longitudinal traction for a dorsal dislocation or hyperflex for a volar dislocation. Gradually push the dislocated phalanx into its normal anatomic position.[11, 12] Do not apply vigorous traction in a child, because that may interpose soft tissue or an osteochondral fragment into the distracted joint space and prevent reduction. After reduction, examine the affected joint for flexor-extensor tendon function, active range of motion, localized tenderness, and instability in the medial-lateral and dorsal-volar directions. Immobilize the joint with a foam-padded splint immediately after reduction to prevent redislocation or instability.
Joint instability or neurovascular compromise after reduction requires immediate orthopedic or hand consultation. Because joint instability or dysfunction and subtle ligamentous, cartilaginous, or bony injury often are obscured by extensive edema and pain immediately after the injury, all finger joint dislocations should be referred for orthopedic or hand specialist evaluation within 2-3 weeks following reduction.
If joint reduction by means of closed manipulation is not feasible due to interposition of periarticular soft tissues, an irreducible dislocation is diagnosed. Irreducible dislocations of the proximal interphalangeal joint are rare injuries. However, every physician should recognize these injuries and immediately refer them to a hand surgeon.[13]
Patients whose digits have neurovascular compromise, an open joint dislocation, ligamentous or volar plate rupture, joint instability, or an associated fracture should have immediate orthopedic consultation. All finger dislocations should be reevaluated subsequently by an orthopedic or hand specialist to manage potential subtle ligamentous, cartilaginous, or bony injury.[11, 12] A lateral or volar PIP joint dislocation, although rare, requires an orthopedist for possible open reduction with internal fixation. A dislocation of the metacarpophalangeal (MCP) joint, although rare in adults, may be more common in children.[14, 15, 16] MCP dislocation usually requires open reduction by a pediatric orthopedist.
Also see Joint Reduction, Finger Dislocation and Joint Reduction, Thumb Dislocation.
History usually reveals a traumatic athletic injury or entrapment of the finger between objects. Typically, the finger was jammed or bent backward during a basketball, football, or other sports activity. The patient often experiences diffuse pain, swelling, and tingling.
Determine the following aspects of the patient's history:
Which is the dominant hand of the patient and which hand is injured?
What is the patient's occupation?
Where did injury occur (eg, job, assault)?
How much time has passed since the initial injury?
An accurate and detailed examination often requires digital block anesthesia. The clinician should test and document each of the following[11, 12] :
Gross deformity, diffuse edema, ecchymosis, and tenderness of the involved digit
Possible anesthesia or paresthesia in the distal aspect of the involved digit
Range of motion, function, and stability of involved joint
Detailed neurovascular examination of the entire involved hand
Restriction in active flexion and extension, especially against resistance, suggests tendinous or ligamentous rupture or intra-articular osteochondral fragment.
Test the integrity of the volar plate by passive hyperextension.
Test the collateral ligaments by exerting radial and ulnar stress.
Skin laceration after a blunt hyperextension injury suggests volar plate rupture.
Take anteroposterior, true lateral, and oblique radiographs of the affected digit. Obtain 3 views prior to and after reduction (see the images below).[17]
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Anteroposterior view of distal interphalangeal (DIP) joint dislocation
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Lateral view of distal interphalangeal (DIP) joint dislocation
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Oblique view of distal interphalangeal (DIP) joint dislocation
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Oblique view of proximal interphalangeal (PIP) joint dislocation
Physeal, avulsion, or distal tuft fractures, as well as osteochondral fragments, are often subtle and seen only on 1 or 2 views.
Obtain stress views to assess joint stability.
Features to note on radiographs include the following[18] :
Percentage of articular surface involvement
Articular step or gap
Comminution or fragmentation
Number of fracture fragments
Joint subluxation or dislocation
When there is joint subluxation, a V sign is seen, which describes an asymmetric joint space seen on a true lateral radiograph.
Splint, ice, and elevate the affected digit.[11, 12] Evaluate neurovascular status before and after transport to the ED. The patient should not participate in sports activities involving the hand.
The patient should have a follow-up evaluation with an orthopedist or hand specialist.
Reduction and postreduction procedures
With the patient's hand or foot securely braced, grasp the dislocated phalanx with dry gauze loosely wrapped around the phalanx (gauze improves grip). Hyperextend the joint slightly with gentle longitudinal traction for a dorsal dislocation or hyperflex for a volar dislocation. Gradually push the dislocated phalanx into its normal anatomic position.[11, 12]
Do not apply vigorous traction in a child, because that may interpose soft tissue or an osteochondral fragment into the distracted joint space and prevent reduction.
After reduction, examine the affected joint for flexor-extensor tendon function, active range of motion, localized tenderness, and instability in the medial-lateral and dorsal-volar directions.
Immobilize the joint with a foam-padded splint immediately after reduction to prevent redislocation or instability. Immobilize for 14-21 days for a PIP joint dislocation and 10-14 days for a DIP joint dislocation. Buddy taping for 3-6 weeks thereafter allows active range of motion and prevents hyperextension.
For a dorsal PIP dislocation, apply the splint dorsally with the joint in 20-30 degrees of flexion.
One study showed that management of PIP joint dislocations using controlled early mobilization with figure-of-eight splints provided greater range of motion and fewer hospital visits as compared to other splinting techniques.[19]
For a volar DIP dislocation, apply the splint only to the DIP joint on the volar aspect; the DIP should be in full extension. Allow the PIP joint full range of motion.
In children, the cause of dislocation is more likely ligamentous laxity rather than rupture.[14, 15, 20] Immobilization by buddy taping to an adjacent digit for 10-14 days is an acceptable alternative treatment.
Obtain postreduction radiographs. Assess functional stability with stress views. This confirms correct joint alignment and congruity and identifies subtle fractures, especially chip or avulsion fractures.
Assess neurovascular status following reduction.
Admission may be warranted as dictated by a hand consultant or concurrent injuries. NSAIDs may be taken as needed. If an orthopedic or hand specialist is not immediately available for consultation, transfer patients whose reductions are unsuccessful or those who have an unstable joint, open joint injury, or associated epiphyseal or avulsion fracture. [21]
Complications are rare with early reduction, although persistent pain or swelling is common. Despite appropriate management with rest, ice, and elevation, pain and swelling may persist for 6-12 months.[11, 12]
Inadequate immobilization after reduction may result in redislocation.
Prolonged immobilization may result in muscle contracture.
Volar plate injury may lead to recurrent dislocation with chronic laxity, hyperextensibility (swan-neck deformity on active extension), or flexion contracture (pseudoboutonnière deformity without DIP hyperextension).
Late or delayed reduction commonly results in loss of joint motion, joint instability, and limitation of hand function.
Proximal interphalangeal joint (PIPJ) injuries often cause complications, such as ankylosis, joint instability, post-traumatic arthritis, and flexion contracture.[18, 22]
Clinical Context:
DOC for treatment of mild to moderately severe pain, if no contraindications. Inhibits inflammatory reactions and pain, probably by decreasing activity of enzyme cyclooxygenase, inhibiting prostaglandin synthesis.
Clinical Context:
Used for relief of mild to moderately severe pain and inflammation. Administer small dosages initially to patients with small body size, the elderly, and those with renal or liver disease. Doses higher than 75 mg do not increase therapeutic effects. Administer high doses with caution and closely observe patient.
Clinical Context:
Has analgesic, antipyretic, and anti-inflammatory effects. May inhibit cyclooxygenase enzymes, inhibiting prostaglandin biosynthesis.
Clinical Context:
Used for relief of mild to moderately severe pain. Inhibits inflammatory reactions and pain by decreasing activity of enzyme cyclooxygenase, decreasing prostaglandin synthesis.
These agents are used most commonly for the relief of mild to moderately severe pain. Although the effects of NSAIDs in the treatment of pain tend to be patient specific, ibuprofen is the DOC for initial therapy. Other options include flurbiprofen, ketoprofen, and naproxen.
Clinical Context:
DOC for treatment of pain in patients with documented hypersensitivity to aspirin and NSAIDs, those with upper GI disease, or those taking oral anticoagulants.
Pain control is essential to quality patient care. It ensures patient comfort, promotes pulmonary toilet, and aids physical therapy regimens. Many analgesics have sedating properties that benefit patients with injuries.
Grace M Young, MD, Associate Professor, Department of Pediatrics, University of Maryland Medical Center
Disclosure: Nothing to disclose.
Specialty Editors
Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Received salary from Medscape for employment. for: Medscape.
Chief Editor
Trevor John Mills, MD, MPH, Chief of Emergency Medicine, Veterans Affairs Northern California Health Care System; Professor of Emergency Medicine, Department of Emergency Medicine, University of California, Davis, School of Medicine
Disclosure: Nothing to disclose.
Additional Contributors
James E Keany, MD, FACEP, Associate Medical Director, Emergency Services, Mission Hospital Regional Medical Center, Children's Hospital of Orange County at Mission
Disclosure: Nothing to disclose.
Acknowledgements
Tom Scaletta, MD President, Smart-ER (http://smart-er.net); Chair, Department of Emergency Medicine, Edward Hospital; Past-President, American Academy of Emergency Medicine
Tom Scaletta, MD is a member of the following medical societies: American Academy of Emergency Medicine
Charles M. Court-Brown. The Epidemiology of Fractures and Dislocations. www.otaonline.org. Available at https://otaonline.org/book/952/chapter/53360338/the-epidemiology-of-fractures-and-dislocations
Nina Lightdale-Miric, Scott H. Kozin. Fractures and Dislocations of the Hand and Carpal Bones in Children. www.otaonline.org. Available at https://otaonline.org/book/918/chapter/53008857/fractures-and-dislocations-of-the-hand-and-carpal
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