SAGITTAL BAND RUPTURE

Question 1

Aetiology of sagittal band rupture

Answer 1

Traumatic vs. atraumatic

1. Traumatic
   - most common in boxers
   - also known as ‘boxer’s knuckle’
2. Atraumatic
   - inflammatory conditions like RA

Question 2

Anatomy of sagittal bands

Answer 2

Origin = extensor expansion/ hood
Insertion = volar plate and deep transverse MC ligament
Function = primary stabiliser of extensor tendon at MCPJ
- juncturae tendinum are secondary stabilisers

Question 3

Effect of sectioning radial and ulnar sagittal bands

Answer 3

• partial or complete sectioning of ulnar sagittal band does not cause radial subluxation of extensor tendon
• partial or complete sectioning of radial sagittal band will cause ulnar subluxation of extensor tendon into intermetacarpal gully

Question 4

2 factors affecting extensor tendon stability

Answer 4

1. Wrist position
   - instability is greater in wrist flexion
   - instability is less in wrist extension
2. Central vs. border digits
   - instability is greatest in central digits = MF worse
   - instability is least in border digits = LF least unstable due to stability from juncturae tendinum

Question 5

Main radiographic view for MCP joint

Answer 5

Brewerton view

• AP view with dorsum of fingers against cassette
• best view for MC head fractures

Question 6

Management of sagittal band ruptures

Answer 6

Acute vs. chronic rupture

1. Acute ruptures = MCPJ extension splinting or direct repair
2. Chronic ruptures = Direct repair or extensor centralisation procedure

Question 7

Main complication with untreated sagittal band ruptures

Answer 7

MCP flexion deformity due to intrinsic contracture