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Extensor Tendon Injuries

advanced
6 min
28 marks
6 questions
Clinical Scenario
A 28-year-old cricketer presents with inability to extend his right ring finger DIP joint after being struck on the fingertip while fielding. The DIP rests in approximately 30° flexion. He can actively flex but cannot actively extend the DIP. There is tenderness over the dorsum of the DIP joint. X-ray shows no fracture. Separately, his teammate presents with a PIP joint injury where the finger is stuck in flexion at the PIP with the DIP hyperextended.
Clinical photographs demonstrating two common extensor tendon injuries. Left: Mallet finger with DIP flexion deformity at rest and inability to actively extend DIP. Right: Boutonniere deformity with fixed PIP flexion and DIP hyperextension. Both require specific splinting protocols. Mallet finger: DIP extension splint 6-8 weeks. Boutonniere: PIP extension splint allowing DIP flexion.
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Clinical photographs demonstrating two common extensor tendon injuries. Left: Mallet finger with DIP flexion deformity at rest and inability to actively extend DIP. Right: Boutonniere deformity with fixed PIP flexion and DIP hyperextension. Both require specific splinting protocols. Mallet finger: DIP extension splint 6-8 weeks. Boutonniere: PIP extension splint allowing DIP flexion.

Image source: Open Access medical literature (NIH/PubMed Central) • CC-BY License

Questions

Question 1 (4 marks)

Describe the extensor tendon zones and anatomy.

Question 2 (5 marks)

Discuss the diagnosis and management of mallet finger.

Question 3 (6 marks)

Describe boutonniere deformity - pathomechanics and treatment.

Question 4 (5 marks)

What are the principles of extensor tendon repair in different zones?

Question 5 (4 marks)

Describe sagittal band rupture and its management.

Question 6 (4 marks)

What is the role of surgery in extensor tendon injuries?

Exam Day Cheat Sheet

Must Mention

  • •Zones I-VIII (odd = joint, even = bone)
  • •Mallet = Zone I, splint DIP 6-8 weeks
  • •Boutonniere = Zone III, splint PIP with free DIP
  • •Elson test for central slip
  • •DIP flexion critical in boutonniere rehab
  • •Sagittal band = Zone V, tendon subluxation

Common Pitfalls

  • •Wrong zone
  • •Splinting wrong joint
  • •Missing Elson test
  • •Wrong boutonniere mechanism
  • •Missing sagittal band
  • •Wrong mallet classification