April 11, 2024
Coxaplana, Osteochondritis deformans juveniles, Osteochondritis of the hip joint

Legg-calve-Perthes disease is characterized pathologically by AVN of the ossification center of the capital epiphysis, which is ultimately resorbed and replaced, resulting in various degrees of deformity of the femoral head and restricted joint motion.

Etiology of Legg-calve-Perthes disease

A. Trueta Hypothesis

  • Limitation of blood supply (only blood supply, lateral epiphyseal artery) by compression of strong external rotator muscle and limit of elasticity of these vessels is extreme position (age 4-8 years)
  • See. Blood supply of femur in Child

B. Caffey’s Hypothesis

  • Trueta’s theory is incomplete with a high predominance of disease in males since vascular supply is identical in the two genders.
  • It is due to intra-epiphyseal compression of blood supply to the ossification center
  • Coagulation abnormalities cause recurrent thrombosis leading to ischemia and necrosis
  • Genetic predisposition to hypercoagulability play casual roles
    • Polymorphism in factor V Leiden
    • Prothrombin II
    • Methylenetetrahydrofolate reductase (MTHFR)

Bilateral in 10-15 %

Predisposing factors:

  1. Local blunt trauma to the femoral head
  2. Children exposed to maternal smoking
  3. Low socioeconomic status
  4. Urban environment

Classifications of Legg-calve-Perthes disease

Pathology: (Waldenstrom Classification)

A. Incipient or synovitis stage

  • 3-6 months
  • Clinically and radiological silent
  • Initial vascular insult: ossific nucleus become smaller and denser but articular cartilage get its nutrition from synovial fluid (Hypertrophy)
  • Increase medial joint space: WALDERSTROM SIGN

B. Fragmentation and Extrusion:

  • Approximately age: 6-12 months
  • Associated with clinical symptoms
  • Microdamage to ossific nucleus: subchondral fractures
  • After fracture: Synovitis, cartilage, and ligament hypertrophy occurs
  • All stress concentrate on the lateral part of epiphysis {Disintegration of the lateral pillar}

C. Healing , Reossification:

  • Begins after 12 months to 18 months
  • Reossification of the nucleus begins peripherally and progresses centrally as necrotic bone is fully removed
  • Epiphysis regain normally strength and destiny
  • New bone: Trabecular

D. Healing / Remodelling

  • Trabecular replaced by lamellar bone
  • Normal radiodensity

Catterall’s classification

During the fragmentation stage of the disease

a) Grade 1:

  • < 25 % involvement
  • Involve the anterior portion of the epiphysis
  • SMS
    • Sequestrum: NO
    • Metaphyseal reaction: NO
    • Subchondral Fracture: NO

b) Grade 2

  • 25-50%
  • Progress toward the lateral cortex
    • Sequestrum: Junctional clear
    • Metaphyseal reaction: Anterior-lateral
    • Subchondral fracture: Anterior half

c) Grade 3

  • 50-75%
    • Sequestrum: Large junctional sclerosis
    • Metaphyseal reaction: Diffuse anterolateral area
    • Subchondral Fracture: Posterior half

d) Grade 4

  • 100%
    • Whole head involvement
    • Metaphyseal reaction: Central of diffuse
    • Posterior remodeling
Legg-calve-Perthes disease Catterall classification
Catterall’s Classification

Head at risk sign

2 out of 5 signs (+)

  1. A trans radiant ‘V’ on the lateral side of the epiphysis, formed by a small osteoporotic segment, which is seen in the A-P radiograph (Gaze sign )
  2. Calcification lateral to epiphysis (speckled)
  3. Lateral subluxation of the femoral head was measured as an increase in the width of the inferomedial joint space
  4. A horizontal epiphysis line is seen in anteroposterior roentgenogram
  5. Diffuse metaphyseal changes

SALTER AND THOMPSON CLASSIFICATION

Focused on the extent of the superolateral dome of the femoral head that is affected by sub-chondral fractures

Type A disease: Involves less than 50 % of the femoral head and has a good prognosis

Type B disease: Involves over 50 % often with associated lateral pillar collapse and suggests poor outcomes

Herring Classification

Most commonly used classification system and it can be applied early in the fragmentation stage within the first 6 months of clinical symptoms

  • Group A: The hips have no lateral pillar involvement
  • Group B: Over 50% of lateral pillar treatment is maintained
  • Group B/C: 50% loss of height
    • B/C-1: Lateral pillar is less than 2-3 mm wide
    • B/C-2: There is minimal ossification
    • B/C-3: Lateral pillar depressed in relation to the central pillar of the femoral head
  • Group C: There is collapse and loss of over 50 % lateral pillar height

Outcome: Stulberg Grading

To identify the Risk of OA

GradingFeatures
Grade INormal, near-normal head
Grade IISpherical, enlarged head, short neck/ steep acetabulum
Grade IIINonspherical head (Ovoid) but not flat
Grade IVFlat head but no incongruent joint
Grade VFlat head + Incongruent joint

I and II: Spherical + Congruity

III and IV: Asymmetrical + Congruity

V: Asymmetrical +Incongruity

Treatment Options for Legg-calve-Perthes disease

Principle of treatment

  1. Containment of femoral Head
  2. Eliminate reducing weight-bearing
  3. Encourage weight-bearing on abduction
  4. Continue the hip joint motion

Depends Upon:

  • Initial Phase: Restore and maintain mobility
  • Active Phase: Containment and maintenance of full mobility
  • Residual phase: To maintain a malformed hip from processing to OA at an early age

Non-Operative treatment:

  • < 6 years with
  • Herring A or B Hip

Protected weight bearing

Activity restriction to reduce mechanical loading to hip until ossification

Anticoagulants

Botulinum toxins

Anti-resorptive therapy

  • RANKL Inhibitors- Denosumab
  • Bisphosphonates

Bone anabolic therapy- Ibradonate

Intraosseous administration of bisphonates

Children 2-3 years of age

Observed

Once synovitis resolved

  • Active and active assistance ROM
  • Muscle stretching exercises for hip and knee

Children 4 years and Older

Explanation to patient parents

If loss of motion -> Indicates changes in prognosis due to lateral subluxation (Lateral)

Treatment:

  • Bed rest
  • Skin traction
  • Progressive passive and active physical therapy
  • Abduction exercises

If no improvement by the above measures,

  • Closed reduction under GA
  • Per-cutaneous adductor longus tenotomy
  • Followed by an ambulatory abduction cast (PETRIE CAST)-minimum 6 weeks

Active Phase

Operative treatment -> May does not produce a better result than non-operative treatment in the young patient unless the femoral head was severe [Lateral pillar B, B/C]

Orthosis Types:

Nonambulatory/ Weight relievingAmbulatory (B/L)Ambulatory (U/L)
Hip SpicaPetrie abduction castTachdijan trilateral socket brace
Broomstick abduction castNewington orthosis
Toronto brace
Atlanta Scottish rice brace
Birmingham brace

Radiographic Evidence of Healing

  1. The appearance of regular ossification in head
  2. Increased density of the femoral head should disappear
  3. Metaphyseal rarefaction should ossify
  4. Intact lateral column
  5. Normal trabecular bone in the epiphysis

Surgical treatment

Most beneficial if performed in the early stage of fragmentation

< 8 Years:

  • Proximal femoral varus osteotomy (Medial close wedge osteotomy)

> 8 Years:

  • Pelvic osteotomy is often required

Surgical Treatment Options:

  • Femoral varus osteotomy
  • Innominate osteotomy
  • Combined femoral and Innominate osteotomy
  • Valgus osteotomy
  • Shelf arthroplasty
  • Chiari osteotomy
  • Cheilectomy
  • Trochanteric advancement or arrest

Salvage Procedure:

  • Valgus sub-trochanteric osteotomy
    • It redirects the head towards the acetabulum and improves joint congruity, and abductor-lever arm and limb length discrepancy

See also: Developmental dysplasia of the hip (DDH)

See also: Congenital Talipus Equinovarus (CTEV)