EM @3AM: Phalanx Dislocation

Authors: Jose Gomez, MD (EM Resident Physician, UTSW – Dallas, TX); Dustin Harris, MD, FACEP, CAQSM (Assistant Professor of EM/ Attending Physician, UTSW- Dallas, TX) // Reviewed by: Sophia Görgens, MD (EM Physician, BIDMC, MA), Cassandra Mackey, MD (Assistant Professor of Emergency Medicine, UMass Chan Medical School); Alex Koyfman, MD (@EMHighAK); Brit Long, MD (@long_brit)

Welcome to EM@3AM, an emDOCs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.

Answer: Proximal interphalangeal joint dislocation

Epidemiology:

• Phalanx dislocations are common hand injuries that can occur at the proximal interphalangeal (PIP) joint or distal interphalangeal (DIP) joint¹
• Dorsal PIP joint dislocation is the most common¹
• Highest occurrence in males versus females (78.8% vs 21.2%), ages between 10-25 years (51.8%), those playing basketball or football (47.2%)²

Background:

• Dislocations are classified based upon the direction of the distal bone relative to the proximal bone; dorsal, volar or lateral³
• PIP joint dislocations
  • Dorsal: most common, caused by axial loading in hyperextension of PIP, associated with volar plate injury, can lead to swan neck deformity⁴
  • Volar: rare, caused by axial loading in hyperflexion of PIP, associated with central slip injury of the extensor tendon, can lead to boutonniere deformity⁴
  • Lateral: caused by rupture of the collateral ligaments⁴
  • Other associated injuries include:
    • concomitant avulsion fracture
    • open injury
    • foreign body
    • DIP injury
    • nail bed injury⁴

• DIP joint dislocations
  • Dorsal: most common, often open injury, associated with volar plate detachment, which can make reduction challenging⁵
  • Volar: rare, associated with extensor tendon injury⁵
  • Lateral: high association with post-reduction instability⁵
  • Isolated DIP joint dislocation is rare and concomitant injuries seen include:
    • phalanx fractures
    • open injury
    • tendon rupture
    • PIP involvement
    • nail bed injury⁵

Anatomy:

• Collateral ligaments: provide stabilization against radial and ulnar deviation of the IP joints^1,6
• Extensor tendon: found dorsally, extends at the DIP and PIP joint^1,6
  • Central slip tendon: attaches to middle phalanx, allows for PIP joint extension
  • Lateral bands: attach to distal phalanx, allows for DIP joint extension
• Flexor Digitorum Profundus (FDP): flexes the DIP, inserts on volar side of distal phalanx^1,6
• Flexor Digitorum Superficialis (FDS): flexes the PIP, inserts on volar side of middle phalanx^1,6
• Volar plate: reinforces joint capsule and prevents hyperextension of the joints^1,6

Clinical Presentation:

• Usually with history of trauma or sports-related injury
• Finger(s) will be misaligned with associated swelling, erythema, pain, and tenderness at the injured joint^1,7

Evaluation/Diagnosis:

• Obtain history on the mechanism of injury, timing, hand dominance, profession, and any previous hand injuries
• Physical exam: make sure to compare both hands, assess for any other trauma, and perform a post reduction-reduction exam, see emdocs for a guide on a full hand exam
  • Assess skin integrity; look for open wounds, skin puckering⁶
  • Assess sensation to the hand, motor function, vascular status, capillary refill, any obvious deformities, tenderness^1,6
  • Test joint motion:
    • Collateral ligament test: perform with joint in full extension and in 30° flexion, apply radial and ulnar directed force at the joint and look for a widened gap. Angulation >20° indicates instability^1,6
    • Hyperextension: ask patient to straighten the digit out, assess for volar plate injury
      • Elson test: assess for central slip injury; have the patient bend at PIP and ask them to extend the digit while you place resistance distance to it. Normal result: tension felt w/ extension and loose DIP. Abnormal: poor tension w/ extension and a rigid DIP^1,6
    • FDS: brace unaffected fingers in extension and have patient flex injured finger at PIP joint^1,6
    • FDP: hold the PIP in extension while the patient attempts to flex the DIP joint^1,6
  • Assess for rotation or angulation by having patient make a fist; if any digits overlap/scissor then concern for rotational injury^1,6

• Diagnosis confirmed with exam and radiographs, always obtain post-reduction films^1,6
  • 3 views x-rays: AP, lateral, oblique
• V sign: viewed on lateral film; separation of the dorsal base of the dislocated phalanx and the head of the proximal phalanx to the joint. If “V sign” present after reduction, it indicates joint instability, which may require operative treatment⁸

Management:

• Simple dislocations can be reduced and splinted by the ED provider
• A hand surgery consults may be required in the ED if outpatient follow up in a hand clinic requires the patient to be seen by a specialist prior to the referral being placed (please refer to your institution policies regarding this)
• Other indications for hand surgery consult in the ED include: irreducible dislocation or finger continues to dislocate after reduction, concern for open injury, vascular injury, avulsion fracture involving >30% of intra-articular surface, complex fractures, or lateral dislocation^1,6,7
• Consider digital nerve block for pain control prior to reduction.⁷ See ALiEM for guide on this procedure
• Always obtain post-reduction imaging to evaluate for any underlying fractures and test for any joint, ligament or tendon injuries
  • PIP dorsal: Apply traction, then hyperextend at the PIP joint while the other hand applies dorsal pressure to the proximal phalanx. Then flex at PIP joint^1,6
    • Splinting: 30° flexion buddy tapping for 3-6 weeks with early range of motion (ROM) exercises as tolerated if stable.¹⁰ If unstable, extension block splinting with fingers flexed at 20-30° for 2-3 weeks⁶

• PIP volar: Apply traction to finger with the MCP and PIP joints in flexion and then bring the middle phalanx into extension^1,6,7
  • Perform Elson test to evaluate for central slip tendon injury and if positive, urgent hand referral outpatient^1,6
  • Splinting: splint in extension for 4-6 weeks with early ROM exercises as tolerated¹⁰

• PIP lateral: With wrist held in extension and MCP joint in flexion, gently pull traction and rotate the middle phalanx back into position^1,6
  • Consult hand surgery as these often require surgical intervention
  • Splinting: buddy tape for 2-3 weeks

• DIP dorsal: similar technique to PIP dorsal reduction^1,5,6
  • Splinting: 10 to 20° flexion of DIP joint for 2-3 weeks
• DIP volar: similar technique to PIP volar reduction^1,6,7
  • Splinting: full extension of DIP joint for 6 weeks
• DIP lateral: similar technique to PIP lateral reduction^1,6
  • Consult hand surgery as these often require surgical intervention
  • Splinting: 10 to 20° flexion of DIP joint for 2-3 weeks

Disposition:

• Simple dislocations can be reduced in the ED, then splinted, and followed up outpatient, if there are no underlying fractures on post-reduction films and joints/tendon exams are normal^3,6,10,12
• Indications to consult hand surgery as noted above and if it is required for the patient to be seen in an outpatient hand clinic⁶

Pearls:

• Simple dislocations can be reduced and splinted in the ED with primary care follow-up if there are no underlying fractures and joints are stable.
• Hand surgery consult is warranted for open fractures, non-reducible dislocations, large avulsion fracture (>30% articular surface), unstable joints, and if outpatient follow-up requires them to be seen by a specialist while in the ED.
• Always perform a post-reduction hand exam, including x-rays, and evaluate for any tendon injuries, ligament injuries, fractures, or rotational injuries.

Further Reading:

Further FOAMed

• https://www.emdocs.net/evaluating-hand-injuries-in-the-ed/
• https://www.aliem.com/diagnosing-the-central-slip-injury/
• https://www.emdocs.net/evidence-based-approach-to-nailbed-injuries-ed-presentations-evaluation-and-management/

References

1. Taqi M, Collins A. Finger Dislocation. In: StatPearls. StatPearls Publishing, Treasure Island (FL); 2023. PMID: 31855352.
2. Golan E, Kang KK, Culbertson M, Choueka J. The Epidemiology of Finger Dislocations Presenting for Emergency Care Within the United States. Hand (N Y). 2016;11(2):192-196. doi:10.1177/1558944715627232
3. Hile D, Hile L. The emergent evaluation and treatment of hand injuries. Emerg Med Clin North Am. 2015;33(2):397-408. doi:10.1016/j.emc.2014.12.009
4. Caggiano NM, Harper CM, Rozental TD. Management of Proximal Interphalangeal Joint Fracture Dislocations. Hand Clin. 2018;34(2):149-165. doi:10.1016/j.hcl.2017.12.005
5. Chung S, Sood A, Lee E. Principles of management in isolated dorsal distal interphalangeal joint dislocations. Eplasty. 2014;14:ic33. Published 2014 Sep 19.
6. Ahn L, Blomberg J. Phalanx dislocations. Orthobullets. Accessed June 1, 2024. https://www.orthobullets.com/hand/6038/phalanx-dislocations.
7. Proximal interphalangeal dislocation (finger) – WikEM. Accessed June 1, 2024. https://wikem.org/wiki/Proximal_interphalangeal_dislocation_(finger)
8. Lustosa L, Glick Y, V sign of interphalangeal joint dislocation. Reference article, Radiopaedia.org (Accessed on 01 Jun 2024) https://radiopaedia.org/articles/v-sign-of-interphalangeal-joint-dislocation?lang=us
9. Elfar J, Mann T. Fracture-dislocations of the proximal interphalangeal joint. J Am Acad Orthop Surg. 2013;21(2):88-98. doi:10.5435/JAAOS-21-02-88
10. Fractures and dislocations of the hand. In: Egol K, Koval K, Zuckerman J, eds. Handbook of Fractures. 6th ed. Wolters Kluwer; 2020:311–329.
11. Alla SR, Deal ND, Dempsey IJ. Current concepts: mallet finger. Hand (N Y). 2014;9(2):138-144. doi:10.1007/s11552-014-9609-y
12. Childress MA, Olivas J, Crutchfield A. Common Finger Fractures and Dislocations. Am Fam Physician. 2022;105(6):631-639.