PERTHES (LEGG-CALVÉ-PERTHES) DISEASE

Description:
Legg-Calvé-Perthes Disease (LCPD) is a juvenile form of avascular osteonecrosis of the femoral head.[1] The etiology is largely unknown but the pathophysiology is attributed to a disruption of blood supply to the capital femoral epiphysis.[2] A reossification phase follows the initial ischemic insult, which may lead to femoral head deformity and earlier osteoarthrosis (OA).[2-5]

LCPD occurs in youth aged 2 to 14 years (most common ages: 5 to 8 years) in a male-to-female ratio of approximately 5:1 and can present bilaterally in 10 to 15% of patients.[1,6] The diagnosis of LCPD is one of exclusion as secondary causes of juvenile osteonecrosis such as sickle cell, HIV, systemic lupus erythematous, renal failure, bone dysplasia’s, Gaucher disease must be ruled out.[1]

LCPD presents with insidious onset hip/groin pain, antalgic gait, and limited hip range of motion. [1]

Differential Diagnosis:

• Secondary causes of osteonecrosis (sickle cell, HIV, systemic lupus erythematous, renal failure, bone dysplasia’s, Gaucher disease)
• Slipped capital femoral epiphysis (SCFE)
• Stress fracture
• Neoplasm
• Transient synovitis
• Infectious arthritis
• Juvenile Idiopathic Arthritis (JIA)

Exam:
Antalgic gait

Reduction in hip ROM is dependent on disease severity (abduction and internal rotation are earliest motions to be affected)

ROM may provoke pain if there is an associated synovitis

 Investigations:
1. XRay Hip & AP Pelvis:
There are many classification systems for radiological findings with Perthes.  These include Stulberg radiographic classification, Herring’s Lateral Pillar Classification,  and Catterall classification, to name a few.
The Stulberg Radiographic Classification describes the morphology of the femoral head from normal/spherical to flattened.[4] The Stulberg classification also predicts progression to OA with the incidence of OA higher in the more advance grades. [4] To note, in early disease, radiographic findings may be absent or nonspecific. Repeat plain film or alternative imaging modalities (i.e. MRI) should be used if there is a high index of suspicion for LCPD.

Stulberg Radiographic Classification [4]:

Class I: Normal Hip Joint

Class II: Spherical head with enlargement, short neck, or steep acetabulum

Class III: Nonspherical head (ie, ovoid, mushroom-shaped, umbrella- 
shaped)

Class IV: Flat head

Class V: Flat head with incongruent hip joint

Lateral Pillar Classification (see Figure 1):
AP radiograph representation of femoral head and epiphysis broken into three groups.

A:  Normal height of lateral pillar
B: Loss of lateral pillar height but >50%
B/C: 50% loss of lateral height
C: Less than 50% of lateral pillar height

Groups B and C have significantly poorer prognoses.[8]

Figure 1:  Lateral Pillar Classification (Lateral pillars highlighted in black)

2. MRI +/- gadoliunium

Management:

The goal of LCPD management is prevention of femoral head deformation and early osteoarthritis through containment of the femoral head within the acetabulum during the reossification phase to allow spherical molding.[2] Femoral head containment can be achieved operatively or nonoperatively.[7] Nonoperative treatments include physiotherapy (ROM, traction, muscle release) and bracing which may include a Petrie cast.[8] Operative technique include innominate osteotomy and femoral osteotomy. [3]

There is limited evidence to allocate patients to surgical or nonsurgical management; however, prognostic indicators of poor outcome include:[1,4,5]

• Higher Stulberg grade
• Older age at onset
• Extent of subcondral fracture (by Salter-Thompson Classification)
• Extent of head involvement at the fragmentation site (by Catteral Classification)
• Two or more of Catteral “head-at-risk” signs (lateral subluxation, lateral calcifica- tion, diffuse metaphyseal reaction, horizontal growth plate, Gage sign)
• Lateral pillar height at the fragmentation stage (lateral pillar classification)
• Premature physeal closure

After diagnosing/highly-suspecting LCPD, consultation with a pediatric orthopedic surgeon experienced with LCPD is warranted.

Figure 2 – Pertie’s Cast Illustration
Casting of lower limbs in abduction to maintain appropriate femoral head location in acetabulum

.

References:

1. Kim HK (2010) Legg-Calve-Perthes disease. J Am Acad Orthop Surg 18: 676-686.

2. Kim HK (2012) Pathophysiology and new strategies for the treatment of Legg-Calve-Perthes disease. J Bone Joint Surg Am 94: 659-669.

3. Hsu JE, Baldwin KD, Tannast M, Hosalkar H (2012) What is the evidence supporting the prevention of osteoarthritis and improved femoral coverage after shelf procedure for Legg-Calve-Perthes disease? Clin Orthop Relat Res 470: 2421-2430.

4. Stulberg SD, Cooperman DR, Wallensten R (1981) The natural history of Legg-Calve-Perthes disease. J Bone Joint Surg Am 63: 1095-1108.

5. Wiig O, Terjesen T, Svenningsen S (2008) Prognostic factors and outcome of treatment in Perthes’ disease: a prospective study of 368 patients with five-year follow-up. J Bone Joint Surg Br 90: 1364-1371.

6. Molloy MK, MacMahon B (1966) Incidence of Legg-Perthes disease (osteochondritis deformans). N Engl J Med 275: 988-990.

7. Herring JA, Kim HT, Browne R (2004) Legg-Calve-Perthes disease. Part II: Prospective multicenter study of the effect of treatment on outcome. J Bone Joint Surg Am 86-A: 2121-2134.

8. Review of orthopaedics. 5th ed. ed. Philadelphia: Saunders / Elsevier; 2008.

Dr. David Lawrence  (August 28, 2014 PR ND)