Legg Calve Perthes disease

Legg Calve Perthes disease

Legg Calve Perthes disease refers to idiopathic osteonecrosis of the femoral head, usually affecting children 3 to 12 years old with a mean age of 7 years.

Radiographic findings include a small femoral head epiphysis, which may become fragmented, and widening of the articular space, which may be due to an associated joint effusion.

7 Interesting Facts of Legg Calve Perthes disease

1. Legg Calve Perthes disease is idiopathic osteonecrosis of the pediatric femoral head
2. It occurs most commonly in 4- to 8-year-old White boys and presents with a painful or nonpainful limp
3. Diagnosis is usually made by findings on plain anteroposterior and pelvis/frog-leg lateral radiographs
4. All children require referral to a pediatric orthopedic surgeon for management when Legg-Calvé-Perthes is suspected
5. Treatment goals are to decrease inflammation in hip, maintain range of motion, and contain femoral head in acetabulum
6. Treatment is nonoperative or operative, depending on age of child and degree of hip involvement
7. Disease most often heals spontaneously, without functional impairment at maturity

• Legg Calve Perthes disease is idiopathic osteonecrosis of the pediatric femoral head
• Self-limited disorder in 60% to 70% of children; usually resolves within 1 to 2 years 

Classification

• Herring lateral pillar classification (most commonly used) 
  • Lateral pillar refers to the lateral 5% to 30% of the femoral head on an anteroposterior radiograph, which is demarcated from the central portion of the head by a lucent line of fragmentation that delineates the central necrotic area. If lucency is not present, the lateral 25% of the femoral head is considered to be the lateral pillar
    • Group A hips: necrosis does not involve the lateral pillar
    • Group B hips: there is limited pillar involvement, with maintenance of over 50% lateral pillar height
      • B/C border group: the lateral pillar is approximately 50% depressed
        • B/C 1 group: over 50% of lateral pillar height remains, but it is less than 2 to 3 mm wide
        • B/C 2 group: over 50% of lateral pillar height remains but has minimal ossification
        • B/C 3 group: exactly 50% of lateral pillar height remains, but it is depressed compared with the central pillar
    • Group C hips: less than 50% of pillar height remains
  • Lateral pillar height loss has been well correlated with the final radiographic outcome and is a better predictor than age of onset
• Modified Stulberg
  • Classification system used to predict the onset of degenerative joint disease after Legg-Calvé-Perthes hips are mature
    • Class I: normal hip joint
    • Class II: femoral head is round and fits within 2 mm of a circle on both anteroposterior and frog-leg lateral radiographs
    • Class III: femoral head is ovoid and does not fit within 2 mm of the circle on either view
    • Class IV: femoral head with at least 1 cm of flattening of the weight-bearing articular surface on one or both views
• Catterall classification 
  • Stage I: clinical diagnosis without radiographic findings
  • Stage II: sclerosis with or without cystic changes, with preservation of the contour and surface of the femoral head
  • Stage III: loss of structural integrity of the epiphysis
  • Stage IV: loss of structural integrity of the acetabulum in addition to the epiphysis

Clinical Presentation

History

• Classic presentation is painless limp or antalgic gait with insidious onset
• Limp may be particularly prominent after strenuous activity at the end of the day
• If present, pain is localized in the anterior hip, but it can be referred to the anteromedial thigh or knee

Physical examination

• Decreased hip range of motion with abduction and internal rotation
  • Unilateral in most cases, but occurs bilaterally in approximately 10% 
• Mild hip flexion contracture of 10° to 20° may be present
• Positive Trendelenburg test result
  • Inability to maintain a stable (horizontal) pelvis level while standing on affected limb
• Gait is often antalgic
  • Shortened stance phase on affected side

Causes

• Hip disorder that results from temporary interruption of blood supply to proximal femoral epiphysis
• Etiology is unknown

Risk factors and/or associations

Age

• Peak ages are from 4 to 8 years 

Sex

• Affects boys more than girls at a ratio of 5 to 1 

Genetics

• Increased familial risk
  • Most cases display a multifactorial inheritance pattern, but rare autosomal dominant cases occur 
  • Autosomal dominant form (OMIM #150600) is associated with germline mutations in the COL2A1 gene, which encodes type II collagen 

Ethnicity/race

• More common in White patients 

Other risk factors/associations

• Delayed bone age (2 years in girls and 1 year in boys) 
• Impaired growth in height
• Low birth weight (may be secondary to maternal smoking) 
• Passive smoke exposure 
• Maternal smoking during pregnancy 
• Extreme obesity 
• Incidence increases with increase in latitude 
• Socioeconomic deprivation 

Diagnostic Procedures

Primary diagnostic tools 

• In any child between ages 4 and 8 years with a limp, suspect Legg-Calvé-Perthes, complete a hip examination, and obtain plain radiographs
• History and physical examination suggest the disorder, but imaging is required for a formal diagnosis
• Plain radiography of pelvis and hip is used in all patients for diagnosis and follow-up 
• MRI is useful when plain radiograph findings are negative early in the disease, or to define the extent of disease
• Arthrography is useful to the orthopedic subspecialist to define extent of disease and plan surgical intervention

Imaging 

• Radiography: anteroposterior and frog-leg lateral views of pelvis
  • Initial findings
    • May be normal early in the disease (ie, for the first 3 to 6 months)
    • Femoral head appears smaller than the contralateral, unaffected femoral head
    • Medial joint space is widened
    • Subchondral lucent region that is associated with subchondral collapse
    • Irregular physeal plate
    • Radiolucent and blurry metaphysis
  • Fragmentation phase
    • Fragmented epiphysis
    • Increased radiolucency in areas of new bone formation
  • Reossification phase
    • Femoral head widens and flattens
  • If there is bilateral involvement, the stages of the hips will usually not be identical
• MRI 
  • Delineates the extent of bony infarction and the anatomy of the cartilaginous head and labrum
    • More accurate in the early diagnosis and provides earlier and more accurate detail on the extent of femoral head necrosis and proximal femoral physeal involvement and femoral head and acetabular deformities 
  • There is an evolving role for perfusion, diffusion, and delayed gadolinium-enhanced MRI in determining prognosis 
    • Perfusion MRI may be useful to demonstrate the extent of loss of perfusion to the femoral epiphysis
• Arthrography 
  • Aids in assessing range of motion and ability to contain the head in the acetabulum
  • Used to evaluate the relationship between the femoral head and acetabulum when surgical treatment is indicated

Differential Diagnosis

Most common

• Transient synovitis
  • Acute onset of hip pain following a viral illness, characterized by:
    • Unilateral involvement with restricted motion and minimal pain
    • Spontaneous improvement over 24 to 48 hours
  • Differentiate from Legg-Calvé-Perthes by:
    • Radiography: transient synovitis shows normal results on radiographs
    • Disease time course: transient synovitis symptoms resolve over several days
• Septic arthritis
  • Joint infection presenting with fever, unilateral pain, and decreased range of motion
  • Differentiate from Legg-Calvé-Perthes by:
    • History: septic arthritis has a more acute onset and fever is typically present
    • Laboratory studies: elevated WBC count present in septic arthritis, and joint fluid aspiration will show signs of infection
    • Imaging: radiography and ultrasonography will show widened joint space with septic joint
• Multiple epiphyseal dysplasia
  • An unusual genetic disorder with bilateral epiphyseal dysplasia in both hips at the same stage and with the same degree of involvement
  • Differentiate from Legg-Calvé-Perthes by radiographic findings and family history 
    • Legg-Calvé-Perthes is most often unilateral, but when it occurs bilaterally, the hips are in asymmetrical stages, in contrast to multiple epiphyseal dysplasia where the epiphyses are symmetrically flattened, fragmented, and slightly sclerotic
    • Multiple epiphyseal dysplasia typically has strong family history
    • Multiple epiphyseal dysplasia occurs at other joints in addition to the hips
• Sickle cell disease
  • Sickle cell disease symptoms usually begin in early childhood and include pain, repeated infections, and chronic anemia
  • Differentiate from Legg-Calvé-Perthes by:
    • Laboratory studies: anemia and hemoglobin S on electrophoresis
      • Sickle cell disease is hereditary, so thorough family history will typically include the disorder; Legg-Calvé-Perthes occurs sporadically
• Spondyloepiphyseal dysplasia
  • Autosomal dominant chondrodysplasia characterized by short stature, abnormal epiphyses, and flattened vertebral bodies
  • Bilateral epiphyseal dysplasia with spine involvement, known as platyspondyly, is a constant finding
  • Differentiate from Legg-Calvé-Perthes by:
    • Spine radiographs
    • Multiple joint involvement

Treatment Goals

• Restore hip range of motion, then achieve and maintain containment of femoral head in acetabulum
• Control pain
• Prevent osteoarthritis

Disposition

Admission criteria

• Need for traction or surgery

Recommendations for specialist referral

• All cases require orthopedic evaluation; when Legg-Calvé-Perthes is suspected, the child should be referred to a pediatric orthopedic surgeon for evaluation and prompt initiation of treatment

Treatment Options 

Treatment is aimed at containing femoral head within acetabulum to prevent deformation by muscular forces and weight-bearing stresses on fragile bone

Specific treatment modalities used to achieve this goal depend on age and stage at presentation and are determined by a pediatric orthopedic surgeon

• Initial options to manage symptoms are nonoperative and include activity limitation, protected weight-bearing, and NSAIDs 
  • Other nonoperative treatments include crutches and physical therapy
  • Nonoperative containment treatment, which positions the anterior-lateral portion of the femoral epiphysis within the acetabulum, can be undertaken using Petrie casting and abduction bracing 
  • Nonoperative treatment is considered for patients with less severe hip involvement, such as: 
    • Lateral pillar A or B, without extrusion, with onset younger than age 8 years
    • Lateral pillar A or Catterall class I or II, without extrusion, with onset up to age 11 years
• Surgical containment can be achieved through intertrochanteric femoral osteotomy or pelvic osteotomy 
  • Goal of surgery is to restore normal anatomy and optimal joint congruency to prevent degenerative deterioration of hip
  • Additional procedures that may become necessary are the following:
    • Isolated proximal femoral osteotomy, with the hip centered and internally fixated to achieve correct so-called femoroacetabular containment
    • Osteochondroplasties
    • Labrum procedures
    • Osteotomies for acetabular realignment
    • Acetabuloplasties
  • Surgical containment was thought to result in best outcomes when performed in children over 8 years old with Catterall classes III or IV and in those with lateral pillar class B or B/C border hips 
    • However, it’s now believed to be most effective when initiated in the early stages of disease (prior to when the lateral pillar classification can be made in late fragmentation) or prior to hip extrusion regardless of age
• Patients younger than 6 years 
  • Operative and nonoperative methods have the same likelihood of a favorable outcome
  • When surgery is done, pelvic procedures are more likely than femoral procedures to result in good radiographic outcomes
• Patients 6 years or older
  • Operative methods (osteotomy) are more likely to yield a spherical congruent femoral head than nonoperative methods 
  • When surgery is done, both the femoral and pelvic procedures are equally likely to result in a good radiographic outcome

Drug therapy 

• NSAIDs
  • At dose and schedule recommended by the pediatric orthopedist

Nondrug and supportive care 

Activity limitation and protected weight-bearing are initial measures that are recommended for all patients

Under guidance of an orthopedic surgeon and/or a physical therapist, the following additional nonsurgical modalities may be recommended:

• Physical therapy, to regain range of motion
• Casting, to attenuate inflammation and synovitis
• Bracing
  • Positions the femur in abduction and rotation through use of orthotic devices
  • Scottish Rite brace achieves containment by abduction while allowing free knee motion

Procedures

Osteotomy

General explanation

• Femoral osteotomy done during the stage of avascular necrosis permits bypass of the stage of fragmentation in one-third of children 
• Main operative procedures are proximal femoral osteotomy and pelvic osteotomy (shelf arthroplasty)
• The goal is to restore normal anatomy and optimal joint congruency to prevent degenerative deterioration of the hip

Indication 

• Herring lateral pillar classification
  • Group B hips: when onset occurred after the age of 8 years
  • Group B/C hips: all
  • Group C hips: all
• Fragmentation stage of the femoral head
  • More involved hip requires surgical intervention

Complications

• Trochanteric overgrowth
  • Sole significant predictor is lateral pillar height, with much greater risk of trochanteric overgrowth development in lateral pillar type C hips (44%) compared with types B and B/C hips (10%) 
• Leg length discrepancy
  • Sole significant predictor is the extent of lateral pillar involvement
• Osteoarthritis
  • Develops in adulthood and is related to disease severity and earlier age of disease onset 
  • May require hip replacement or other surgical intervention 

Prognosis

• 60% to 70% of affected hips heal spontaneously without functional impairment at maturity 
• Long-term outcome
  • Most important anatomical determinant is the femoral head shape/extrusion
    • Extrusion of the femoral head is the major factor that determines future degenerative arthritis
    • High chance of the femoral head becoming deformed when more than 20% of the width of the femoral head extrudes 
  • Clinical factors that affect long-term outcome
    • Age at onset
      • Onset prior to six years old confers a good prognosis 
      • Bone age more than 6 years at presentation confers a poorer prognosis 
      • Patients with onset after 11 years have a poor prognosis regardless of treatment type 
    • Radiographic stage
      • Stronger determinant of prognosis than age
      • Catterall class III/IV and lateral pillar class C are associated with poor outcomes even when onset is at a young age 
    • Hip range of motion
      • Worse prognosis with greater impairment
    • Course of disease 
      • Worse prognosis with sequential, but not concurrent, onset of bilateral disease

References

1: Ippolito E et al: The long-term prognosis of unilateral Perthes’ disease. J Bone Joint Surg Br. 69(2):243-50, 1987 Reference