hand
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.
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