IP JOINT DISLOCATIONS

Question 1

Classification of PIP dislocations

Answer 1

1. Dorsal = most common
2. Volar
3. Lateral

Question 2

Dorsal PIP dislocations

Answer 2

• hyperextension injuries
• avulsion of volar plate off distal attachment into P2 = may lead to swan neck deformity
• simple = subluxations
• complex = complete with volar plate interposition
• structures blocking reduction = volar plate +/- FDS insertion
• management with dorsal blocking splint

Question 3

Volar PIP dislocations

Answer 3

• hyperflexion injuries
• avulsion of central slip = may lead to boutonnaire deformity
• simple = subluxations
• rotatory = disruption of one of collateral ligaments, proximal phalanx condyle buttonholes between central slip and lateral band
• structures blocking reduction = dorsal capsule +/- central slip
• management with PIP extension splint

Question 4

Lateral PIP dislocations

Answer 4

• radial/ ulnar force
• avulsion of one of collateral ligaments and partial disruption of volar plate
• structures blocking reduction = lateral band

Question 5

Dorsal PIP fracture-dislocations

Answer 5

Mechanism:
1. Avulsion = hyperextension causing tensile failure of volar lip (attachment of volar plate)
2. Impaction shear = axial load through flexed PIPJ causing shear fracture of volar lip
Management = dorsal/ extension blocking splint

Question 6

Volar PIP fracture-dislocations

Answer 6

Mechanism:
1. Avulsion = hyperflexion causing tensile failure of dorsal lip (attachment of central slip)
2. Impaction shear = axial load through extended PIPJ causing shear fracture of dorsal lip
Management = PIP extension splint

Question 7

2 indications for surgical management of PIP fracture-dislocations

Answer 7

1. Failure of closed reduction = soft-tissue interposition
2. Subluxed joint = if > 1/3 articular surface involved
   - joint reduction more important than restoration of articular congruity for outcome

Question 8

Dorsal DIP dislocations and fracture-dislocations

Answer 8

1. Mechanism
   - tensile failure in hyperextension
   - shear failure in flexion
2. Structures blocking reduction
   - volar plate
   - FDP insertion
3. Management = dorsal splint in slight flexion

Question 9

Volar DIP dislocations and fracture-dislocations

Answer 9

1. Mechanism
   - tensile failure in hyperflexion
   - shear failure in extension
2. Structures blocking reduction
   - dorsal capsule
   - terminal extensor tendon
3. Management = extension splint