Perthes DIsease Current Concepts

Perthe's disease- aetiology:
G. C. Perthes in Germany, J. Calvé in France and A.T. Legg in America described the disease almost simultaneously, in 1910.

Synonyms: Coxa Plana; osteochondritis deformans juvenilis

Aetiology:

Theories and Supporting Evidence
1. Compromised Vascular supply: Angiograms and laser Doppler flow studies showing that the medial circumflex artery is missing or obliterated in many cases and that the obturator artery or the lateral epiphyseal artery are also affected in some cases.

2. Increased intra-articular pressure:
Animal experiments have shown that an ischemia similar to that in Legg-
Calvé-Perthes disease can be generated by increasing the intra-articular pressure

3. Raised Intraosseous pressure The venous drainage in the femoral head is impaired, causing an increase in intraosseous pressure

4. Coagulation disorder
Association with Protein C or S deficiency. These factors normally inhibit coagulation

5. A maturation disorder Legg- Calvé- Perthe’s disease patients are shorter, on average, than their peers of the same age and show a retarded skeletal age

6. Social conditions: Studies in the UK have shown that Legg- Calvé- Perthes disease is more common in the lower social strata

7.Genetic factors: Genetic studies have shown that first degree relatives of children with Perthe’s disease are 35 times more likely to suffer from the condition than
the normal population.

Classifications
Catterall’s Head-at-risk Signs
1. Lateral subluxation of the femoral head from the acetabulum.
2. Speckled calcification lateral to the capital epiphysis.
3. Diffuse metaphyseal reaction (metaphyseal cysts).
4. A horizontal physis, and
5. Gage sign: A radiolucent V-shaped defect in the lateral epiphysis and adjacent metaphysis.

Salter Thompson Classification
• Type A: Extent of the fracture is less than 50% of the superior dome of the femoral head. Good results.
• Type B: Extent of the fracture is more than 50% of the dome. Fair or poor results.

Herring Lateral Pillar Classification
• Group A: No involvement of the lateral pillar.
• Group B: At least 50% of lateral pillar height maintained.
• Group C: Less than 50% of lateral pillar height maintained.

The lateral pillar consists of the lateral most 30% of the femoral head in an AP projection. To designate borderline groups between B and C the B/C border group was included.
B/C1: lateral pillar more than 50% width, but < 2 to 3 mm width
B/C2: lateral pillar more than 50% width, but little ossification
B/C3: lateral pillar more than 50% width, but depressed relative to central column.

Catterall Classification
• Group I: Anterior part of head involved.
• Group II: Anterior and partial lateral involvement.
Sequestrum+ Mild metaphyseal changes
• Group III: Anterior and lateral head involvement
Sequestrum + Diffuse metaphyseal changes + Coxa
magna
• Group IV: Complete head involvement
Collapse of head


stages
Stages of Perthe’s Disease (Waldenström Staging)

Stage and Characteristics
1. Avascular stage. The femoral head appears slightly denser than normal on the x-ray and is slightly flattened; the joint space is widened (Waldenström sign).
Lateralisation of the femoral head.

2. Stage of resorption (Fragmentation). Femoral head breaks up into fragments
Lucent areas appear in the femoral head
Increased density resolves
Acetabular contour is more irregular

3. Stage of reossification. The femoral head is rebuilt
New bone formation occurs in the femoral head

4. Healing stage. End stage with or without defect healing (normal hip, coxa magna, coxa parva, flattened head etc.)


Clinical Features:

• Limp and mild to moderate hip pain
• The ROM of the hip is restricted, in particular abduction and internal rotation.

Prognostic Features:
• Deformity of femoral head, Age, subluxation, lateral calcification, mobility and sex in decreasing order of significance
• Herring lateral pillar classification has the best prognostic significance
• Gage sign and Horizontal growth plate as originally described by Caterall have no prognostic significance

Differential Diagnosis:
1. Epiphyseal dysplasia: The following are features
Bilateral involvement
Largely symmetrical findings
Possible involvement of other joints or the spine
Possible involvement of the acetabulum
Few sclerotic or cystic changes in the femoral head
Little tendency toward lateral calcification or subluxation
Typical stages of LCPD like sclerosis, collapse, fragmentation and reossification are not apparent

2. Osteochondritis dissecans of the femoral head
3. Chondroblastoma of the femoral head
• The height of the femoral head is not initially reduced, nor is the
cartilage thickened.
• The presence of non-load-related pain

Stages of radiological changes in Perthe's disease:
Early
• Joint space widening(waldenstrom's sign)
• Increased density of femoral epiphysis
• Subchondral fracture, or “crescent sign,” seen on lateral radiograph
Midstage
• Fragmentation and flattening of head
• Widening of the physis
• Femoral neck cysts
• Extrusion of the femoral head
Late
• Coxa magna
• High-riding trochanter
• Flattened femoral head
• Irregular articular surface

Perthe’s disease features:
Unilateral involvement,
If bilateral involvement is present: pronounced asymmetry, disease in differing stages, possibly also of differing severity,
No involvement of other joints or the spine,
No involvement of the acetabulum,
Sclerotic and cystic changes in the femoral head,
Cystic changes in the metaphysis,
Tendency toward lateral calcification and subluxation


DD
Other disorders associated with Avascular Necrosis of the femoral head in children:

Sickle cell anemia
Thalassemia ((high incidence (25%) of avascular femoral head necrosis ))
Trichorhinophalangeal syndrome
Klinefelter syndrome
Morquio’s syndrome
Down syndrome (trisomy 21)
Achondroplasia
Gaucher’s disease
 Myelomeningocoele
Hemophilia (the incidence in hemophilia is 7%)
 Congenital tibial pseudoarthrosis


Treatment
Treatment is guided my dividing the patient into three groups.

Poor prognosis group: Treatment indicated:
• Catterall 3 and 4
• Salter-Thompson
• Lateral pillar C
• At risk clinically
• At risk radiographically, regardless of the disease extent
• Age<8yrwithdeformity
• Age >8 yr (Catterall group 2, 3, and 4, with or without at-risk signs; lateral pillar B and C; Salter-Thompson B), with or without head deformity

Good prognosis group: no treatment necessary:
• Catterall 1 and 2(generally good prognosis in 90% of cases)
• Salter-Thompson A
• Lateral pillar A
• If disease is in reossification stage

Indeterminate prognosis group: may require treatment if head at risk signs is present. Otherwise no treatment is indicated.
• Catterall 2
• Lateral pillar B

Principles of treatment• The first principle regardless of the method of treatment is restoration of motion.
• Restoration of motion can be accomplished by bed rest alone, or with skin traction and progressive abduction to relieve the muscle spasms
• Reassessment is done in 1 week to assure that range of motion has considerably improved (to at least 45 degrees of abduction
• The cornerstone of treatment for Legg-Calve-Perthes syndrome is referred to as containment
• The essence of containment is that, in order to prevent deformities of the diseased epiphysis, the femoral head must be contained within the depths of the acetabulum
• Arthrography is a useful adjunct in determining whether the femoral head actually can be contained and, if so, in what position this is best accomplished.
• It is essential to regain range of motion before instituting containment treatment
• Hinged abduction: This is a condition in which the head levers out of the acetabulum with abduction instead of moving within the socket
• Demonstration of the hinge abduction phenomenon is a contraindication to any type of containment treatment
• Surgical containment (Varus Derotational Osteotomy / Innominate Osteotomy/ Lateral Shelf acetabuloplasty) is the most popular method of treatment
• Abduction brace like the Atlanta Scottish Rite orthosis are used by surgeons who prefer nonsurgical containment

• The requisites for an varus derotation intertrochanteric osteotomy are:
1. Epiphyseal plate not too steep,
2. No major leg shortening,
3. Congruency between the femoral head and the acetabulum,
4. Ability to contain the femoral head in the acetabulum in abduction and internal rotation
5. Only slight restriction of abduction


• Pre requisites for an innominate osteotomy (Salter’s osteotomy) include:
1. Restoration of a full range of motion,
2. A round or almost round femoral head, and congruency of the joint, demonstrated arthrographically.
3. The head must be well seated in flexion, abduction.
• Combined varus derotation and innominate osteotomies are being evaluated for Caterall 3 and 4 stage disease

• Shelf Arthroplasty: is becoming popular as a method of containment
Prerequisites-
1. Children older than 8 years with Catterall group 2, 3, or 4 disease with or without at-risk signs,
2. Lateral pillar type B or C disease, and
3. Salter-Thompson type B disease;
4. If subluxation is present, it must be reducible on a dynamic arthrogram

Risk factors for poor results with this technique are age older than 11 years, female gender, and Catterall group 4 disease.
• Triple Innominate osteotomy as a method of containment is being investigated
• Arthrodiastasis: the use of hip distraction for periods of 4 to 5 months, with or without soft tissue release, in older children with Perthes disease is also being investigated


Management of the Noncontainable Hip
Management of the Noncontainable Hip and the Late-presenting Patient with Deformity:

• These include patients in later stages (reossification) of the disease, those with noncontainable deformities, and those who have lost containment after undergoing either surgical or nonsurgical containment
• These patients usually demonstrate hinge abduction on arthrography.
• The salvage procedures to be considered at this point include abduction extension osteotomy, lateral shelf arthroplasty, Chiari osteotomy, and cheilectomy
• These salvage procedures are done with limited aims of pain relief, correction of limb length inequality and improvement of movement and abductor weakness
• Cheilectomy removes the anterolateral part of the head that impinges on the acetabulum in abduction
Cheilectomy does not correct any residual shortening or abductor weakness
This procedure should only be done after the physis has closed, otherwise an
SCFE may ensue.
• Chiari Osteotomy improves the lateral coverage of the head, but does not give coverage to the deformed head in abduction and it may exacerbate abductor weakness
• Abduction extension osteotomy is indicated when arthrography demonstrates joint congruency in extended and adducted position
This osteotomy improves the limb length, decreases limp and improves function and range of motion