AO basic course

1. AOTrauma Principles Course
Femoral neck fractures
Piet de Boer, UK
Ian Harris, AU
Mariusz Bonczar, PL

2. Objectives
• Outline the biological and mechanical problems in
treating femoral neck fractures
• Identify the indication for fixation and arthroplasty

3. Anatomy, classification
31B

4. Blood supply
lateral circumflex artery
medial circumflex artery

5. Anterior

6. medial circumflex artery
posterior

7. Blood supply
The posterior retinuacular vessels from the medial circumflex artery
provides the main nutrition to the femoral head
cranial anastomosis
biological effect

8. Classification of proximal femoral fractures
trochanteric
area-
extracapsular
31-A
neck fracture –
intracapsular,
extraarticular
31-B
head fracture-
intracapsular,
intraarticular
31-C

9. AO Classification
• Subcapital with slight
displacement
• Valgus position
• Mostly impacted
• Breakdown of trabecular
line
• Elderly patients
• Low energy
• Osteoporosis
• Female
B1

10. AO Classification
• Transcervical
• Different fracture line
angle and position
• Displacement
• Younger patients
• High energy
• Male
B2

11. AO Classification
• subcapital displaced
• No impaction
• Different degree of displacement
B3

12. Garden classification (1961)
• High degree of interobserver variation
• Difficult to predict complication ( esp. grade III and IV )
• Only division on undisplaced ( I, II) and displaced (III, IV)
I II III IV
appearance of the trabeculae of the femoral head on AP X-ray

13. Pauwels classification (1935)
• High degree of inter and intraobserver variation
• Preoperative angle has no correlation with the subsequent
• Incidence of complications (except undisplaced fractures)
< 30° 30° - 70° > 70°
shearing forces at the site of fracture

14. Classification?
what does determine outcome?
• Displacement―undisplaced vs displaced
• Stability―stable vs unstable
valgus impacted are stable

15. Incidence
Elderly
• Majority
• Low energy
• Osteoporosis
• Female
Young
• High energy
• Male

16. Diagnosis
• AP and lateral x-ray
• Hip pain in elderly patient post-fall with normal x-ray
- Bone scan
- “Limited” MRI (magnetic resonance imaging)
- CT (computed tomography) scan

17. Classification
• Displaced (stable) vs undisplaced (unstable)
• Valgus impacted are stable

18. Do not reduce!
impacted
valgus
stable

19. Prognosis
Depends on displacement
• Avascular necrosis
• Nonunion
• Osteoarthritis
• Deformity (shortening, varus)

20. Undisplaced fractures
• Internal fixation will result in only 10% failure rate
• Safe and simple to fix
- Percutaneous or mini-open

21. Indication for fixation
Impacted and undisplaced fracture: cannulated screws—
implant of choice
minimal exposure
parallel to allow
compression

22. Displaced fractures
Elderly patients (the majority)
• High rate of failure for internal fixation
• Joint arthroplasty gives most reliable results
- Early weight bearing
- Lower failure rate
Young patients
• Internal fixation is more reliable than in elderly
• Arthroplasty is less reliable

23. Treatment algorithm
displaced
under 55 55-85 over 85

24. Internal fixation
Reduction
• Traction table
• Open reduction if required

25. Internal fixation
• Multiple cannulated screws
• Dynamic hip screw

26. Internal fixation
Multiple cannulated screws
• Minimal exposure
• Parallel to allow compression
Dynamic hip screw
• Increased stability
• Increased exposure and bone loss
• Allow compression

27. Internal fixation

28. Internal fixation—complications
• 30% fixation failure/loss of reduction
• Avascular necrosis
• Nonunion

29. Indications for arthroplasty
• Primary: Elderly, low demand, osteoporotic
• Secondary: Failed fixation, nonunion

30. Arthroplasty—options
• Hemi- vs total joint arthroplasty
• Bipolar vs unipolar
• Cemented vs uncemented
• Approach

31. Arthroplasty—options

32. Arthroplasty—options
• In the elderly, cement is preferred
• No significant difference between bipolar and unipolar
• Hemi-arthroplasty vs total hip
- Smaller operation
- Lower dislocation rate
- May not last as long as total joint replacement
• Anterolateral vs posterior approach

33. Arthroplasty—complications
• Dislocation
• Infection
• Acetabular erosion
• Leg length inequality

34. Further reading
Internal fixation vs arthroplasty:
• Cochrane
• Orthopaedic Trauma Directions

35. Treatment is mechanically based…
Results are biologically dependent!

36. Summary
• Prognosis is dependent on displacement
• Internal fixation is indicated for all undisplaced (stable)
fractures, and for all fractures in young patients
• Arthroplasty is indicated for displaced fractures in the
elderly