Definition: Self limited
idiopathic affection of the femoral head characterised by avascular necrosis of the whole or a part of the head, produced
by interrupted blood supply followed by sub-chondral fracture, re-vascularisation and repair of dead bone.
A part of group of disorder known as osteochondroses characterised by avascular necrosis
of primary and secondary centres.
Commonly involved primary centre –
Tarsal navicular bone (Kohler’s),
Vertebral body (Calve’s).
Commonly involved secondary centre -
Apophysis and epiphysis of capitellum (Panner’s),
Metatorsal head (Freibergs) and capital femoral
Epiphysis of femoral head (Perthe’s).
– 12 yrs. usually 4 - 8 yr with mean at 7yr of age. 10 -20% are bilateral & familial in 10%.
Predisposed child - delayed bone age, low birth weight & low socio-economic status.
Blood supply to the head is through three main vessels
1. Metaphyseal vessels
2. Lateral epiphyseal vessel
3. Small supply from ligamentum teres.
The metaphyseal supply gradually decreases by the age of four years and vessels in
the ligamentum teres are not well developed till seven yrs of age. Thus betweeen 4 - 8 yrs, the epiphysis is solely dependent
on ascending retinacular artery for the supply which are suspectable to the external pressure form the effusion probability
related to retinacular vessel occlusion, raised intra-capsular pressure, intra-epiphyseal thrombosis, vascular irregularities
or increased vascular Idiopathic capital femoral ischemia (Initial information)
Temporary cessation of growth of epiphysis
Epiphyseal revascularisation from the periphery.
Resortption of avascular bone and production of woven bone
Potential form of Perthe’s disease
Revascularisation leads ot increased resorption compared to the worven bone depostion
and if the critical point of stress is reached, results in path. fracture
Re-resorption of underlying bone and replacement by biologically plastic (woven)
— Bio-plasticity and re-modelling
Pathological Stages :-
A. Ischemia / Necrosis - All or a part of the
head dies at which time the x-rays remain normal. The head stops enlarging but the cartilage still nourished by diffusion
from synovial fluid continues to grow with increased apparent joint space and apparent mild subluxation known as the Waldenstorm’s
cessation of the growth of head lasts 6-12mths.
B. Fragmentation / Resorption :
• The trabeculae in the dead bone giving rise to increased density on x-ray.
• Hyperemia and re-vascularisation causes bone resorption and the head becomes
rarefied / cystic.
• Lysis of the bone occuring at the supero-lateral portion of the head forms
a lytic ‘V’ or Gage sign.
C. Reossification / Resolution.
• The stage of resorption and reossification run hand in hand with new bone
being laid down on the dead trabeculae.
D. Remodelling :
• If repair / revascularisation is rapid, the head may maintan its shape –
the biological plasticity.
• The head may collapse further – resulting in flattening / fragmentation.
• Abnormal stresses transmitted to the growth plate may cause distortion to
• Coxa magna secondary to premature physeal arrest and hypertrophy of the epiphyseal
• Lateral portion of the head becomes uncovered.
• If alternation of shape persists – early degenerative changes.
Clinical Features :
2. Pain – dull aching, sometimes refered to knee and may even be absent.
3. Limitation of abduction and internal rotaion;
Catterral sign of obligatory external
rotation may be present i.e on flexion of hip the limb goes into external rotation.
4. Trendlenburg’s test is positive.
5. Muscle wasting is present.
1. Radiographs : The x rays will show typical
changes in the head depending on the stage & things that help in determining the prognosis are :
a) Salter extrusion angle : it less than 50° suggest poor prognosis.
b) Salter extrusion index >20% suggest poor prognosis.
2. MRI : Helps in early diagnosis
• Since complete head cannot be seen on the x rays, it helps in identifying
area of epiphyseal infractions and the contours of the femoral head, both of which are prognostically important.
3. Arthrogram : It is a dynamic investigation.
So determines the best portion to splint the position of containment and appropriate planning of the osteotomy.
Catterral’s ‘head at risk signs’ : Suggestive of a poor prognosis are :
1. Lateral subluxation of the head (head partially uncovered)
2. Involvement of the whole head.
3. Metaphyseal cysts.
4. Calcification lateral to the epiphysis.
5. Horizontal physis.
6. Gage sign – ‘V’ shaped metaphyseal indentation laterally.
- Obligatory external rotation on flexion
– Catterral’s sign
- Poor range of movements
- Flexion deformity
- Internal rotation deformity
Overall indicators for poor prognosis
1. Female sex
2. Bone age more than 10yr
3. Uncovering of the femoral head.
4. More than 50% head involved
5. Loss of the hip range of movement
6. Premature physeal closure.
Anatomic and prognostic classification – depending on the state and involvement
— The epiphyseal plate
— Metaphyseal changes
A. Catterral’s Classification
Has large inter and intra observer variation
• Antero-medial portion of the head and no collapse.
• Epiphyseal plate not involved.
• No metaphyseal change
• Heals without significant sequelae.
Stage II: Lateral pillar intact
• More head involved and fragmentation of the involved segment.
• The involved segment show increased density, but the uninvolved pillar of
bone prevent its significant collapse.
• The metaphyseal reaction is localised.
• Regeneration occurs without much loss of the height and the result is usually
Stage III: Involvement of the lateral margin
• More of the head involvement, collapse occures as the un-involved pillars
are not large
enough to prevent collapse.
• May show head-with-in head appearance (Crescent sign).
• Metapghyseal involvement is usually widespread
• Result is poorer.
Stage IV: Whole head involvement
• Severe collapse
• Extensive metaphyseal changes
• Epihyseal plate often involved – abnormal growth occurs - coxa magna,
or coxa valga may occur.
B. Salter Thompson Classification
Stage A = Lateral portiono of the capital epiphysis
is present i.e catterral’s 1 & 2 or roughly speaking less than 50% head involved.
Stage B = Lateral portion of capitla epiphysis
is absent i.e catterral’s 3 & 4 or more than 50% involvement of the head.
C. Herring’s Classification
A.- No collapse of lateral pillar
B.- Lateral pillar margin - more than 50% of original height is maintained
C.- Laterall pillar - collapse of more than 50%.
Deformities at Maturity:
1. Coxa Magna
2. Hanging rope sign. - indicative of severe epiphyseal disturbance, seen on x-ray
as line present in neck droping down distally.
3. Coxa Brevis: Short neck with overgrowth of the trochanter as a result of premature
4. Coxa irregularis : collapse and lateral extrusion of the femoral head, forming
under the lateral edge of the acetabulum.
5. Osteochondritis dessicans.
classification of healed Perthe’s
1. Spherical congriuty (< 2mm head deformation measured by moss’ circles)
2. Aspherical congruity
3. Aspherical in-congruity.
1. Elimination of hip irritability
2. Restoration and maintance of the range of movement
3. Prevent epiphyseal extrusion and subluxation.
4. Attainment of spherical head on healing.
Concept of containement: It is believed that during avascular phase the head is soft, so by re-distributing the compressive forces healing
and re-modelling can be facilitated. (The concept of biological plasticity).
This can be done by
1) Making the child non weight bearing for 18 - 24 months till head ossifies but
this is not a practical measure
2) Containment procedures.
Current concept of management
2) Intermittent symptomatic treatment.
3) Early definitive treatment.
4) Surgical treatment of the exisiting deformity.
1) Appropriate for all children under 6 yr of age, regardless of any stage except
there is/are head at risk sign(s).
2) More than 6 years, catterral’s grade 1 & 2 without any head at risk
sign. However in Indian patients, it is believed that any child above 7 yrs specially
females with any stage more than catterral’s grade I, even without head at risk sign should be offered containment surgery.
B. Intermittent symptomatic treatment
Periodic treatment with complete bed rest and abduction stretching exercises in these
cases associated with hyper-irritability and a temporary decrease in ROM commonly in phase of subchordral fracture
Definitive surgical management in early
Containement procedures - Indications
1. Age > 6 years.
2. Class III and IV catterral’s or Grade II Salter-Thompson’s
3. Head at risk signs.
Prerequisite -- Full
range of motion with no residual irritability.
Non surgical methods - Abducation casts eg: Petrie’s brace, Toronto brace, Synder sling, Tachdjian’s brace, Atlanta scottish
rite brace, Newington abduction brace.
Surgical method - Advantages
1) Period of restriction less than 2 month
2) Permanent containment
3) Better containment & hence better femoral remodelling.
Procedures - MRI preferably done before surgery
a) Varus derotation osteotomy (VDRO)
ii) Coxa vara (prevented by adding the procedure of trochanteric arrest)
iii) Trendlenburg’s gait.
Advantage - can be used when significant
femoral antetorsion is present.
b) Innominate osteotomy
(1) Better anterior & lateral coverage
(2) No shortening
(3) No coxa breva.
Late surgical procedures:
1) Hinge abduction - with normal abduction rotation of the femoral head occurs about
locus in the centre of the femoral head. With the hinge abduction, the centre of
rotation is shifted to the lateral edge of acetabulum, while the infero-medial corner continues to move laterally, the superior
portion of the head is prevented from moving medially.
2) Malformed head -cheilectomy
3) Coxa Magna - shelf osteotomy
4) large malformed head subluxation – Chiari’s ostertomy
5) Capital femoral physeal arrest – Trendlendburg’s gait - Trochanteric
advancement procedure of Wagner may be required.