Avascular necrosis (AVN) of the femoral head is a pathologic process that results from interruption of blood supply to the bone. AVN of the hip is poorly understood, but this process is the final common pathway of traumatic or nontraumatic factors that compromise the already precarious circulation of the femoral head. Femoral head ischemia results in the death of marrow and osteocytes and usually results in the collapse of the necrotic segment

1. AVASCULAR NECROSIS OF FEMORAL
HEAD
D R . S AY F A L D E E N H U S S A M
O R T H O P E D I C T R A I N E E
B A G H DA D M E D I C A L C I T Y

2. INTRODUCTION
• Avascular Necrosis (AVN) of the femoral head is a pathological
process that results from interruption of the blood supply to the
bone Also known as Osteonecrosis
• Occurs in 10% of Non displaced femoral neck fractures,
and 15-50% of Displaced femoral neck fractures.
• Occurs in 10-25% of traumatic hip dislocations
• Men:Women = 4:1
• Atraumatic AVN is bilateral in 30-70% but typically asymmetrical.
• M/c site Anterolateral aspect (Wt. bearing portion)

3. BLOOD SUPPLY OF FEMORAL HEAD
• The major sources are the Lateral Epiphyseal
Vessels from Medial Femoral Circumflex
Artery
• LEV supplies lateral and central thirds of the
femoral head
• When patent, the Artery of Ligamentum
Teres (ALT) supplies medial third of the
femoral head.

4. Etiology
TRAUMATIC
• Displaced hip fractures
• Hip dislocation
• Iatrogenic sec. to anterograde
nailing
ATRAUMATIC
• Most are Idiopathic
• Corticosteroid use,
• alcohol abuse,
• smoking,
• Hemoglobinopathies
• myeloproliferative disorders
(Gaucher disease, leukemia),
• hyperbaric decompression,
• hyperlipidemias
• infection.

5. Symptoms
• Non specific signs and symptoms
• Early Painless.
• Ultimate presentation Pain and limitation of motion.
• Mostly localized to groin area but may also manifest in the
ipsilateral buttock, knee or greater trochanter region.
• Mechanical Pain

6. examination
• Passive ROM limited and painful, esp. forced internal rotation.
• Distinct limitation of passive abduction.
• SLR( straight leg raising )against resistance provokes pain.
• “Log-roll”test may elicit pain consistent with active capsular
synovitis.
• Patients with chronic symptoms may have flexion contractures.

7. IMAGING STUDIES
• X-rays:
A-P and frog-leg lateral (cross table lateral is less satisfactory)
Early changes not visible but, over time, a predictable pattern of
radiographic change becomes evident.

9. ANGLE OF KERBOUL
• To calculate, first identify the
center of the femoral head. Two
lines are then drawn from this
point to the borders of the lesion
on both AP and lateral
radiographs. The sum of the
angles on the AP and lateral
radiographs is the Kerboul angle.
Lesions are classified as small,
medium, or large.

10. MRI Findings
• Classic Findings:- look for focal lesion in the anterosuperior
portion of femoral head that is well demarcated but is
inhomogeneous
• T1 images low signal intensity
• T2 images High signal line inside a low signal line
(double-line sign.)
• high-signal-intensity line may represent hypervascular
granulation tissue

11. TYPICAL HYPOINTENSE
BAND IN THE T1 WEIGHTED
IMAGE
T2 WEIGHTED IMAGE
HIGH SIGNAL LINE INSIDE
A LOW SIGNAL LINE
(DOUBLE-LINE SIGN.)

12. CT SCAN
• Useful only in separating late pre-collapse stage from early collapse

13. BONE SCAN
• Technetium 99 bone scan reveals decreased uptake
• It is effective only if done in early stages During late phase there are
very variable results.

14. STAGING
Disadvantages:
-Relies only on plain radiographs, which are unrevealing early signs.
-No measurement of lesion size or articular surface involvement.

15. ARCO staging
• The most widely used classification
system is ARCO( Association
Research Circulation Osseous)

16. Shimizu classification
• Shimizu classification based on MR images which defines the
extent, location and intensity of the abnormal segment in the
femoral head
• extent: the area of the coronal femoral head image involved
• Location: the portion of the weightbearing surface in the initial
MRI
• Intensity: The intensity of the signal on the coronal T1W spin echo
images

18. TREATMENT
• Medical management:
• INDICATIONS:-
1- Alternative to surgical management
2-Small, Asymptomatic lesions
3-Poor medical condition
4- Following certain types of surgical procedures, such as core
decompression, grafting, and osteotomies (used as an adjunct)

19. Conservative measures
1- Limit weight bearing
2-Pain medications.
3-Immobilization
4-Bisphosphonates :
- Delay collapse of the femoral head
- Delay the need for surgical intervention.
5-Statin therapy: Prevents corticosteroid-induced AVN

20. • EXTERNAL, BIOPHYSICAL, NON OPERATIVE MODALITIES
• Pulsed Electromagnetic Field stimulation
• Extracorporeal Shockwave Therapy
• Hyperbaric oxygen (HBO)
• Bone Marrow Injections

21. Surgical procedures
• Joint Preserving
1-Core Decompression
2- Various Nonvascularized &
Vascularized Bone Grafting
Procedures
3- Osteotomy Procedures
• Joint Replacing
1-Total Hip Arthroplasty
2- Hip Resurfacing Procedures

22. CORE DECOMPRESSION
• INDICATIONS:
• ARCO stage I and IIA – small central lesions in young ,
Non obese patients who are not taking steroids
• ADVANTAGES:
• relatively simple to perform
• a very low complication rate
• The surgical field for subsequent total hip
arthroplasty, if needed, is not substantially altered

23. BONE GRAFTING
• Bone grafting procedures are a group of joint preserving
techniques that involve the removal of the diseased femoral head
segment, followed by its replacement with 1 or more of a variety
of bone graft options.
• These are most valuable in treating patients with Stage I & II
disease

24. TECHNIQUES OF BONE GRAFTING
• Grafting through lateral core track

25. Grafting through femoral neck window

26. Grafting through articular
surface window

27. Types of Bone Grafts
Nonvascularized Grafts
• are typically prepared as several
struts that provide structural
support under the articular surface
within the evacuated segment
• This construct is often augmented
with cancellous bone graft in an
effort to improve its
osteoconductive and/or
osteoinductive properties
Vascularized Grafts
• Local pedicled grafts,which do
not require microvascular
reanastomosis eg :Muscle-
pedicle bone grafts
• Vascularized pedicle bone grafts
• Free vascularized grafts, which
require a microvascular
reanastomosis. eg: Free
vascularized fibula graft

28. OSTEOTOMIES
• The main biomechanical effect is to rotate the necrotic or
collapsing segment of the hip out of the weight bearing zone,
replacing it with a segment of articular cartillage of the femoral
head supported by healthy viable bone.
• Additionally, may also reduce venous hypertension and decrease
intramedullary pressure

29. TYPES OF OSTEOTOMIES
• 2 main types have been described:
1-Trans-trochanteric rotational osteotomy
2-Intertrochanteric varus or valgus osteotomy(usually combined with
either flexion or extension)

30. IDEAL PATIENT FOR OSTEOTOMY
• Not being treated with long term steroids
• Minimal osteoarthritic changes, with no loss of joint space or
acetabular involvement
• Small combined necrotic angle
• Disadvantages:
• Technically demanding
• Subsequent conversion to THR may be difficult

31. Hip Resurfacing Procedures
Indications :-
• Later stages of osteonecrosis (ARCO Stage III–VI)
• > 30% femoral head involvement
Advantages:
• Hip resurfacings may be easier to revise
• Decreased risk of hip dislocation.
• More normal walking pattern

32. Disadvantages
• Femoral neck fracture.
• Metal ion risk
• Hip resurfacing is a more difficult operation

33. Total Hip Replacement
• treatment for advanced
osteonecrosis of the hip ARCO
Stages IVB–VIC
• Excellent pain relief &
functional improvements

34. Miscllaneous Procedures
• FEMORAL ENDOPROSTHESIS
• ARTHRODESIS
• RESECTION ARTHROPLASTY
• ACRYLIC CEMENT INJECTION
• POROUS TANTALUM ROD INSERTION

35. PROGNOSIS
• Depends on the disease stage at the time of diagnosis
• More than 50% of patients with AVN require surgical treatment within
3 years of diagnosis.
• Half of patients with subchondral collapse of the femoral head develop
AVN in the contralateral hip.
Poor prognostic factors:
• Age older than 50 years
• Advanced disease (stage 3 or worse) at the time of diagnosis
• Non-modifiable risk factors such as cumulative dose of corticosteroids
(corticosteroid- induced AVN)