Vascular and Growth Disorders

Question 1

Osteonecrosis

Answer 1

Death of the osseus cellulr components and marrow due to impaired blood supply.

Epiphyseal necrosis = avascular necrosis

Metaphyseal/Diaphysis necrosis = bone infarct

Causes

• Fat emboli
• Septic emboli from infection
• Caissons disease (nitrogen gas emboli)
• Fat deposition in arteries
  
  • Hyperlidemia, Alcholism, Cushing’s Disease
• Collagen disorders
  
  • RA, SLE, Vasculitis, Increased corticosteroid use
• Vascular
  
  • Sickle cell anaemia, Pregnancy (pressure from uterus impairs venous drainage)
• Radiation
• Gout
• Gaucher’s Disease

Pathogenesis (4 phases)

• Avascular: Loss of blood supply and bone death
  
  • Joint swelling, loss of bone density, collapse of bone
• ​Revascularisation: Infiltration og new blood vessels, resorption of dead bone and deposition of new bone
  
  • Fragmentation, Decreased size of epiphysis, flattening, sclerosis
• Repair and Remodelling: Increased bone deposition, new bone easily remolded - may lead to deformity
  
  • Sclerosis
• Deformity: Dependent on the amount of compressive force through the joint during healing

Radiographic Signs

• Plain films has poor sensitivity and may take months before visible on x-ray/CT
• Increased joint space due to intracapsular swelling
• Ill-defined mottling of trabecular pattern within first weeks to months
• Bone scans will show changes within weeks
• MRI will show changes from days to weeks
  
  • Low signal intenisty in segmental pattern
• Collpase of articular cortex
• Subchondral fracture
  
  • Weakneing of subchiondral bone - fracture seperates cortex from underlying cancellous bone = cresent sign
• Fragmentation
• Decreased bone size
• Sclerosis and subchondral cysts
• Boney deformity

Question 2

Avascular Necrosis: Legg-Calve-Perthes Disease

Answer 2

Femoral capital epiphysis

Demographics

• 5:1 male
• 3 to 12 years; peak incidence 5 to 7 years
• Prognosis better for younger age group (<4yrs), worsens with later onset
• Bilateral in 10% of cases (rare in female)
• Familial incidence in approx. 6 – 12%
• Rare in black children

Clinical Features

• Vague groin pain, possibly to anteromedial knee
• Possible limp
• Pain on abduction and internal rotation
• Chronic: atrophy of thigh muscles

Pathogenesis

• The femoral head vascular supply is derived from 3 primary sources:
  
  • Foveal vessels penetrating through ligamentum teres
  • Superior and inferior epiphyseal vessels from medial and lateral circumflex branches of profunda femoris
  • Metaphyseal vessels from the bone marrow
• The femoral head epiphysis is vulnerable to vascular compromise between the ages of 4 – 7 yrs, because:
  
  • Foveal and metaphyseal vessels are negligible at this age
  • The majority of blood supply comes from epiphyseal vessels, especially the lateral group

Radiographic Features

Early radiographic signs (avascular phase) (0 – 12 months)

• Joint effusion – increased medial joint space
• Waldenstrom’s sign
  
  • (Waldenström sign is the increased distance between the pelvic teardrop and the femoral head. It is a highly specific sign of a hip joint effusion.)
• Decreased bone density
• Small femoral head epiphysis

Later changes: Revascularization phase (6 months – 4 years)

• Articular collapse
• Subchondral fracture: crescent sign
• Fragmentation & separation of fragments
• Flattened small epiphysis
• Homogenous sclerosis (snowcap sign)
• Patchy sclerosis
• Widening & shortening of femoral neck

Repair-remodelling phase (1-2 years)

• Sclerosis as new bone laid down
• Fragments reform then migrate back into shape
• Remodelling of epiphysis and reconstitution of density

Deformity

• Flattened femoral head (mushroom cap deformity)
• Widened and shortened femoral neck
• Enlarged greater trochanter
• Coxa vara deformity
• Shallow acetabular cup
• Secondary OA changes

Question 3

Spontaneous Osteonecrosis of the Knee (SONK)

Answer 3

• Slightly inc female
• > 60yrs
• Sudden onset of pain
• Radiographic signs unremarkable initially
• Unknown aetiology
• Medial femoral condyle – weight bearing surface
• Similar to DJD but:
  
  • Only in femur
  • No joint space loss
  • No osteophytes
  • Crescent sign

Question 4

Freiberg’s Disease

Answer 4

• Females 5:1
• 13 – 18yrs
• Pain, swelling on activity
• Usually 2nd metatarsal head
• Note: flattening of 3rd MT head in this image

Question 5

Keinboch’s Disease

Answer 5

• Avascular necrosis of lunate
• Male 9:1
• 20 -40yrs
• Possible history of acute/chronic trauma
• Worsening pain and disability
• Increased with negative ulnar variance

Question 6

Preiser’s Disease

Answer 6

Note increased density of proximal portion of scaphoid due to avascular necrosis

Question 7

Kohler’s Disease

Answer 7

• Navicular
• Male predominant
• 4 – 10yrs
• Local pain and swelling
• Patchy sclerosis
• Collapse and fragmentation
• Bone scan differentiates from growth variation

Question 8

Truamatic Epiphyseal Injuries: Osgood-Schlatter’s Disease

Answer 8

• Increased males, 11-15yrs, traumatic history, bilateral 25- 50%
• Localised pain and tenderness tibial tubercle
• Clinical diagnosis
• Not osteonecrosis – inflammatory process

Question 9

Traumatic Epiphyseal Injuries: Scheuermann’s Disease

Answer 9

• Not osteonecrosis – possible traumatic growth arrest or endplate fractures
• Active in adolescent years
• 13 – 17yrs
• Slightly males
• Asymptomatic - painful
• “Tiredness” in back
• Poor posture
• Adolescent kyphosis
• 8% population
  
  • (7.19% of clinic patients)

Radiographic Features

• T6 – L2 most common
• Radiographic diagnosis:
  
  • 3 consecutive segments with at least 2 of:
    
    • Schmorl’s nodes / endplate irregularities
    • Anterior wedging of 5o or more
    • Increased A-P diameter
    • Increased kyphosis
  • Loss of disc height

Question 10

Traumatic Epiphyseal Injuries: Post Scheuermann’s Disease

Answer 10

• Only active during adolescent years
• Radiographic changes maintained
  
  • Hyperkyphosis
  • Irregular endplates/multiple schmorl’s nodes/limbic bones
  • Loss of disc height
  • Anterior wedging
  • Sagittal elongation of body
• Premature disc degeneration

Question 11

Osteochondritis Dissecans

Answer 11

• Small necrotic fragment subchondral bone
• Unknown etiology
• Trauma?
• Shearing, rotary or tangentially applied forces involved
• Occasional acute traumatic episode
• Primary vascular occlusion?
• Hereditary tendency?
• Males 11 – 20 yrs
• Asymptomatic, or intermittent locking & giving way, swelling
• Knee, ankle, elbow, hip
• Small dense fragment of detached bone within radiolucent defect with sclerotic concave border
• Fragment may detach

Question 12

Growth Varients of the Epiphysis

Answer 12

Question 13

Sever’s Disease

Answer 13

• Not avascular necrosis of calcaneus
• Mistaken diagnosis of avascular necrosis of calcaneus due to radiographic appearance in children/adolescents presenting with heel pain
• Normal calcaneus, achilles traction apophysitis causing heel pain

Question 14

Sinding-Larsen-Johansson

Answer 14

• Inc male 10-14yrs
• Swelling, pain, inability to run
• Traction apophysitis inferior patella