trauma
Atypical Femoral Fracture
advanced
6 min
26 marks
6 questions
Clinical Scenario
A 76-year-old woman presents after sudden onset of left thigh pain while walking across her living room. She has been on alendronate for 9 years for osteoporosis. She reports prodromal left thigh pain for 4 months. Examination reveals a shortened, externally rotated left leg with proximal thigh tenderness. She also mentions occasional right thigh discomfort.
AP radiograph of the proximal femur showing transverse subtrochanteric fracture with classic atypical features: lateral cortical beaking (spike), localized periosteal/endosteal thickening, minimal comminution, and transverse orientation. Note the medial cortical thickening representing stress reaction.
Image source: Open Access medical literature (NIH/PubMed Central) • CC-BY License
Questions
Question 1 (4 marks)
What is the diagnosis and describe the ASBMR criteria that define this condition.
Question 2 (4 marks)
Explain the pathophysiology of atypical femoral fractures and the role of bisphosphonates.
Question 3 (5 marks)
What are the challenges in surgical management and how do you address them?
Question 4 (6 marks)
Describe your surgical technique for fixation of this fracture.
Question 5 (4 marks)
What medical management and investigations are required post-operatively?
Question 6 (3 marks)
The patient mentions right thigh discomfort. How do you evaluate and manage this?
Exam Day Cheat Sheet
Must Mention
- •ASBMR criteria: 4 of 5 major features required
- •Lateral cortical beaking = pathognomonic
- •Transverse pattern, minimal comminution, prodromal pain
- •FULL-LENGTH cephalomedullary nail (protect entire femur)
- •Blocking screws to prevent varus
- •Check contralateral femur (25-50% bilateral)
- •Drug holiday + teriparatide
Common Pitfalls
- •Not recognizing atypical fracture pattern (lateral beaking, transverse)
- •Short nail that doesn't protect entire femur
- •Varus malreduction from lateral cortex defect
- •Not using blocking screws
- •Not imaging contralateral femur (25-50% bilateral)
- •Not stopping bisphosphonate (drug holiday essential)
- •Not considering teriparatide for delayed healing
- •Expecting rapid union (delayed union is typical)