01/08/2013 Legg-Calve-Perthes Disease

Georg Perthes ( )

First described by Karel Maydl

Epidemiology  Incidence 1-4/10,000  Age years; average 7 yrs  As early as 2yrs as late as teens  Boys : girls 4:1  Bilateral 10-12%  No evidence of inheritance  Common in Caucasians; rare in black races

Etiology  Idiopathic  Past theories  Infection, inflammation, trauma, congenital  Most theories involve vascular compromise

Pathophysiology  Rapid growth occurs in relation to devt of blood supply  Interruption of blood supply results in necrosis, removal of necrotic tissue, and its replacement with new bone.  Bone replacement may be so complete and perfect that completely normal bone may result  The adequacy of bone replacement depends on  Age of the patient  Congruity of the involved joint

Sources of blood supply  Up to 4years  Metaphyseal vessels  Retinacular vessels  Ligamentum teres – scanty  4 to 7 years  Metaphyseal vessels ceases  Above 7years  Vessels in ligamentum teres have developed

Pathology  Goes through stages which may last 3 to 4 years  Stage1  Ischaemia and bone death, cartilage thickens  Stage 2  Revascularization and repair Dead marrow replaced by granulation tissue Bone revascularized and new bone laid down Dead bone resorbed, replaced by fibrous tissue, fragmentation  Stage 3  Distortion and remodelling Restoration of femoral archtecture or collapse Femoral head displaces laterally in relation to acetabulum

Classification  Waldenstrom classification  Catterall classification  Salter and thompson classification  Herring classification

Caterall classification  Based on amt of involvement of femoral epiphysis  Group I  <1/2 of head involved,  Group II  Up to half of head. Some collapse of central portion  Group III  >1/2 of head involved with sclerosis, fragmentation and collapse of head  Group IV  Entire epiphysis involved

Caterall “head-at-risk” signs  Associated with poor results  lateral subluxation (most important)  calcification lateral to the epiphysis  Gage's sign: V shaped defect laterally  metaphyseal cysts  horizontal growth plate

Caterall “head-at-risk” signs metaphyseal cysts

Gage's sign

Salter and thompson classification  Describes extent of subchondal fracture in the superolateral portion of femoral head  Type A - <50% of femoral head  Type B - >50% of femoral head  can be observed radiographically earlier and more readily tan caterall classification  Can be applied early in course of dz to determine management

Herring classificatin/lateral pillar Based on degree of collapse of lateral pillar during fragmentation stage  Goup A  No collapse, no progressive flattening  Group B  <50% collapse  Group C  >50% collapse Ritterbusch 1993  Has the highest predictive value and interobserver reliability

Bilateral involvement  More severe dz than unilateral  Boys and girls equally affected  Independent event  Bone age delayed in perthes disease

Examination  Short stature  Delayed bone age  Early  Decreased ROM  Antalgic gait  Late  Decreased ROM of motion from acetabular impingement  Disuse atrophy of thigh muscles  Leg lenght descrepancy  Trendelenburg gait

Investigations  Blood tests  haemogram, ESR, CRP  Imaging  Plain X-rays  Hip U/S  Bone scintigrpahy  MRI  Dynamic arthrography  Assess spherity of femoral head  Hinge abduction  Bilateral perthes  Skeleta survey as part of work-up

Song et al MRI findings on widened medial joint space  Initial stage  Overgrowth of cartilage  Fragmentation stage  Overgrown cartilage with widened true medial joint space  Healing stage  Widened true medial joint space

Treatment  Goals of tratment  Maintain femoral head spherity – containment  Avoid severe degenerative arthritis  Guided by  Age  Severity  Limitation in ROM

Treatment cont.  Initial Mx determined by sympts severity  Analgesia  Modification of activities  Bedrest and short period of traction  Wheelchair/crutch walking discouraged  Preserve abduction  Determine bone age

Treatment: Two main choices  Conservative  Pain control  Gentle exercises  Regular re-assessment  Avoid sport and strenous activities  Containment  Hold hips widely abducted in cast/brace >1yr  Operation Varus osteotomy of femur Innominate osteotomy of pelvis Both

Herring Guidelines to treatment  Children <6years  Symptomatic treatment  Children >6years; bone age more imp than chronological age  Bone age at or <6yrs Lateral pillar A or B/ caterall I and II Symptomatic treatment Lateral pillar C/ Caterall III and IV  Bone over 6years Herring A and B/Caterall I and II Abduction brace or osteotomy Herring C/Caterall III and IV Outcome unaffected by treatment  Children 9yrs and older  Except in very mild cases, operative containment is the treatment of choice

oseoclast-osteoblat interaction

Prognostic features  Age  <6yrs; good regardless of treatment  6-9years; not always satisfactory with containment  >10yrs; questionable benefit from containment, poor prognosis  Gender  Girls have worse prognosis  Classification grade  Herrings lateral pillar classification  Salter and thompson grade B worse prognosis  Caterral classification grade  Caterral “head-at-risk” signs  The five signs carry worse prognosis  Others  Body weight, decreased ROM