Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Orthopaedics PPT 4 Avascular Necrosis Lecture Notes
Avascular Necrosis
Learning Objectives
? Atraumatic /Traumatic AVN
? Understand the pathology of AVN
? Progression of disease
? Classification of Hip AVN
? Principles of treatment
27 years old ,pain right groin
? Non smoker, occasional alcohol intake, no medical history
? On examination.
? No Tenderness
? Restricted internal rotation ,painful
? No limp
? CBC Normal, Rheumatoid factor ?ve, ESR 18mm,CRP -6
Radiographs
Q1 Which of the following is an inappropriate
diagnosis?
a) Early Sero-Negative Rheumatoid arthritis
b) Avascular necrosis right hip
c) Tubercular arthritis right hip
d) Torn acetabular labrum
Q 2 The most appropriate investigation for
him is?
a) Tc 99 bone scan
b) MRI scan
c) MARS MRI
d) Contrast enhanced CT Scan
Q3 This is classifiable as Ficat-Arlet-
a) Stage 1
b) Stage 2
c) Stage 3
d) Stage 4
Q 4 The most appropriate treatment ?
a) Non operative with follow up MRI at 6 weeks
b) Non weight bearing and analgesics
c) Bed rest, traction and analgesics
d) Core decompression
Q 5 The patient comes after 2 years and has severe pain in his
hip, decreased ROM and a pronounced limp. Radiographs
reveal collapse of the head with decreased joint space
suggestive of secondary OA. The appropriate management is-
a) Arthroscopic debridement and irrigation
b) Osteochondral grafting
c) Bipolar hip arthroplasty
d) Total hip arthroplasty
Overview
? AVN is a major cause of hip pain
? Traumatic/Atraumatic in etiology
? Evaluation is difficult
? Treatment is hip salvage/Replacement
? Other common areas are ?Humerus, scaphoid, talus and distal femur
Avascular necrosis- Traumatic
? Femoral neck fractures- severance of the blood supply to the femoral
head.
? The capitulum
? Femoral condyles
? Proximal parts of the scaphoid and talus.
Distant parts of the bone's vascular territory
Largely enclosed by cartilage- restricted access to local
blood vessels.
TRAUMATIC OSTEONECROSIS
? Fractures and dislocations of the hip
? Tear of retinacular vessels supplying the femoral head
? Displaced fractures of the femoral neck ? AVN 20%.
fractures of the scaphoid and talus- AVN
? Principal vessels enter their distal ends
? Intraosseous course from distal to proximal.
Closed compartment-Bone
? Vascular sinusoids- no adventitial layer
? Patency - volume and pressure of the
marrow tissue
? Marrow is encased in unyielding bone.
? One element can expand-other gets
compressed
NON-TRAUMATIC OSTEONECROSIS
? Intravascular stasis
? Thrombosis
? Extravascular swelling and capillary compression.
Ischaemia- Multifactorial
? Severance of the local blood supply
? Venous stasis and retrograde arteriolar stoppage
? Intravascular thrombosis
? Compression of capillaries and sinusoids by marrow swelling.
Nontraumatic -AVN
? Perthes' disease,
? Caisson disease
? Gaucher's disease
systemic lupus erythematosus
Sickle-cel disease
Dysbaric ischaemia
Thrombocytopenia
Fat embolism
Arteriolar occlusion
Marrow edema Vascular stasis
Sinusoidal compression
Gaucher's disease
Tuberculosis
Cortisone/alcohol
Dysbaric ischaemia
Normal head femur
Pathology and natural history
? Prolonged anoxia ? Osteocyte death
? Gross appearance remains unaltered
? Striking histological changes in the marrow
? Loss of fat cell outlines
? Inflammatory cell infiltration
? Marrow oedema
? Replacement of necrotic marrow- mesenchymal tissue.
Bone repair?
? New blood vessels and osteoblastic proliferation at the interface
between ischaemic and live bone.
? Vascular granulation tissue advances from the surviving trabeculae
? New bone is laid down upon the dead- creeping substitution
? Increase in mineral mass - increased density or `sclerosis'.
Further progress
? Reparative formation proceeds slowly
? Advances 8?10 mm into the necrotic zone.
? Structural failure begins- most heavily stressed part of the necrotic
segment.
? Linear tangential fracture close to the articular surface.
Stage of arthritis
? Articular cartilage retains its thickness and viability for a long time.
? In the final stages- fragmentation collapse of the necrotic bone
? Progressive deformity and destruction of the joint surface.
Clinical features
? The earliest stage of bone death is asymptomatic
? Patient presents with pain - lesion is usually well advanced.
? Pain in or near a joint
? Few complain of a `click' in the joint- due to snapping or catching of a
loose articular fragment.
Stage of arthritis
? Joint becomes stiff and deformed.
? Local tenderness may be present
? Superficial joints- effusion.
? Movements ?may be restricted
? Advanced cases- fixed deformities.
Radiographs
? The early signs of ischaemia -bone marrow and cannot be detected.
? 3 months after the onset of ischaemia- first sign
? Reactive new bone formation at the boundary of the ischaemic area -
sclerosis
Thin tangential fracture line just below the
articular surface ?the `crescent sign'.
Late -collapse and distortion of the articular
surface
MRI Scan
? The most sensitive modality ? marrow changes are discernable
? The size of the necrotic segment-hypo-intense band in the T1,MRI
AVN ?Distal femur
AVN Talus
AVN -Capitulum
Radionuclide scanning
? 99mTcsulphur colloid- taken up in myeloid tissue.
? Useful in traumatic avascular necrosis- large segment of bone is
involved.
? Sickle-cell disease - `cold' area contrasts significantly with the
generally high nuclide uptake due to increased erythroblastic activity.
Staging the lesion
? Ficat and Arlet (1980) introduced the concept of radiographic staging
for osteonecrosis of the hip
? Early (pre-symptomatic) signs- sclerosis, crescent sign.
? Later features- progressive demarcation and collapse of the necrotic
segment in the femoral head.
Stage 1 ? No radiological changes
? Diagnosis was based on measurement of raised intraosseous pressure
? Histological features of bone biopsy
? MRI
Stage II
? The femoral head contour was still normal
? Early signs of reactive change in the subchondral area
Stage 3
? Signs of osteonecrosis with evidence of structural damage and
distortion of the bone outline.
? Collapse of the necrotic segment
Stage 4
? Collapse of the articular surface and signs of secondary OA.
Diagnosis of the underlying disorder
? Episode of trauma- obvious
? Occupation- deep-sea diving or working under compressed air
? Family background of Gaucher's disease or sickle-cell disease.
? High-dosage corticosteroid administration; renal transplantation.
? Low dose use ?quacks, inappropriate use
? Alcohol abuse is often difficult to determine
? SLE- antiphospholipid antibodies may be measured.
EARLY OSTEONECROSIS
? Bone contour is intact- structural failure can be
prevented.
? Some lesions heal spontaneously and with minimal
deformity;
? Non-weightbearing joints
? Superomedial part of the femoral head
? Non- weight bearing surfaces of the femoral condyles and
talus.
Weight bearing joints
? Poor prognosis-l probably end in structural failure
? Simple measures like non weight bearing- reduce loading.
? If the bone contour is still intact,an `unloading' osteotomy
? Help to preserve the anatomy while remodelling proceeds.
? Medullary decompression and bone grafting may have a
place
Stage II- Core decompression B/L
LATE STAGE OSTEONECROSIS
? Destruction of the articular surface may be give rise to pain and
severe loss of function.
? non-operative management, concentrating on pain control,
modification of daily activities and appropriate, splintage of the joint
? Arthrodesis of the joint, e.g. the ankle or wrist
? Total joint replacement- shoulder, hip and knee.
Q1 Which of the following is an inappropriate
diagnosis?
a) Early Sero-Negative Rheumatoid arthritis
b) Avascular necrosis right hip
c) Tubercular arthritis right hip
d) Torn acetabular labrum
Q 2 The most appropriate investigation for
him is?
a) Tc 99 bone scan
b) MRI scan
c) MARS MRI
d) Contrast enhanced CT Scan
Q3 This is classifiable as Ficat-Arlet-
a) Stage 1
b) Stage 2
c) Stage 3
d) Stage 4
Q 4 The most appropriate treatment ?
a) Non operative with follow up MRI at 6 weeks
b) Non weight bearing and analgesics
c) Bed rest, traction and analgesics
d) Core decompression
Q 5 The patient comes after 2 years and has severe pain in his
hip, decreased ROM and a pronounced limp. Radiographs
reveal collapse of the head with decreased joint space
suggestive of secondary OA. The appropriate management is-
a) Arthroscopic debridement and irrigation
b) Osteochondral grafting
c) Bipolar hip arthroplasty
d) Total hip arthroplasty
Conclusion
? AVN is difficult to diagnose early- High degree of suspicion
? Radiographs in early stages are normal- Trust your findings more!
? Best modality for early diagnosis ?MRI
? Salvage can be tried for Stage I,I
? Advanced stages require ? Total hip arthroplasty
This post was last modified on 07 April 2022