MALLET FINGER Flashcards
1
Q
Long term sequela of untreated mallet finger
A
Swan neck deformity
- overactivity of central slip
2
Q
Anatomy of extensor mechanism
A
- Extensor expansion/ hood over proximal phalanx
- Sagittal bands stabilise extensor tendon at MCPJ
- Extensor tendon trifurcates over proximal phalanx
- Central slip attaches to base of middle phalanx
- Lateral bands pass volar to axis of PIPJ and dorsal to axis of DIPJ
- Lateral bands come together and form the terminal extensor tendon which attaches to base of distal phalanx
- Triangular ligament prevents volar subluxation of lateral bands
- Transverse retinacular ligament prevents dorsal subluxation of lateral bands
- Interossei attach to extensor expansion (before trifurcation)
- Lumbricals attach to radial lateral band (after trifurcation)
3
Q
Classification of mallet finger injuries
A
Doyle classification = 4 types based on open vs. closed injury
- Type I = closed soft-tissue avulsion (most common)
- Type II = open laceration
- Type III = open injury with skin and tendon loss
- Type IV = bony avulsion/ mallet fracture
- IVA = physeal injury
- IVB = bony avulsion involving < 50% of articular surface
- IVC = bony avulsion involving > 50% of articular surface
4
Q
Nonoperative management of mallet finger injuries
A
- Involves DIP extension splinting with volar-based extension splint
- Splinting is full-time for 8 wks then part-time for 4 wks
- Avoid hyperextension = risk of dorsal skin necrosis
- Most patients will end up with 10deg extensor lag
5
Q
2 indications for surgical management of mallet finger injuries
A
- Open injuries
2. Large bony avulsions (> 1/3 articular surface) causing joint subluxation
6
Q
3 main surgical options for mallet finger injuries
A
- Closed reduction and transarticular K-wire
- Extension block pinning
- Open reduction and screw/ K-wire
7
Q
3 main complications with untreated mallet finger injuries
A
- Extensor lag
- most patients will have 10deg extensor lag even with treatment - Swan neck deformity
- DIPJ arthritis
