Definition.
- It is degenerative disease of the hip joint, where growth/loss of bone mass that leads to some degree of collapse of the hip joint and to deformity of the ball of the femur and the surface of the hip socket
- The disease is characterized by idiopathic avascular osteonecrosis of the capital femoral epiphysis of the femoral head leading to an interruption of the blood supply of the head of the femur close to the hip joint
Epidemiology
- Disorder of the hip in young children
- Usually ages 4-8 years
- Boys:Girls= 4:1
- Usually unilateral
Blood supply
Age related changes in blood supply to Epiphysis
Age < 4
Receives blood from the metaphyseal vessels
Age 4-8
Blood from separate epiphyseal vessels as the physis is barrier to blood flow
Age > 8
The ligamentum teres has increasing significance in supply (20%)
Radiographic Stages
Four Waldenstrom stages:
1) Initial stage
2) Fragmentation stage
3) Reossification stage
4) Healed stage
Initial Stage
Early radiographic signs:
- Failure of femoral ossific nucleus to grow
- Widening of medial joint space
- Irregular physeal plate
- Blurry/ radiolucent metaphysis
Fragmentation Stage
- Bony epiphysis begins to fragment
- Areas of increased lucency
Reossification Stage
- Normal bone density returns
- Alterations in shape of femoral head and neck evident
Healed Stage
- Left with residual deformity from disease and repair process
- Differs from AVN(avascular necrosis) following Fx or dislocation
Presentation
- Often insidious onset of limp
- C/O pain in groin, thigh, knee
- The typical patient has a flexion contracture of 0-30 degrees, loss of abduction compared with the opposite side and loss of internal rotation of the hip.
- Can have an acute onset
- Patients frequently have younger skeletal age than cohorts
Physical Exam
- Decreased ROM, especially abduction and internal rotation
- Trendelenburg test often positive
- Adductor contracture
- Muscular atrophy of thigh/buttock/calf
- Limb length discrepency
- Imaging
AP pelvis
Frog leg lateral
Key= view films sequentially over course of dz
Arthrography
Differential Diagnosis
- Important to rule out infectious etiology (septic arthritis, toxic synovitis)
-JRA
-Sickle Cell
-Osteomyelitis
-Traumatic AVN
-Neoplasm
-Medication-steroid
Non-operative Tx
- Improve ROM 1st
- Bracing:
-casts
-Hips abducted and internally rotated for containment
- Wean from brace when improved x-ray healing signs
Bracing
Operative Tx
- If non-op tx cannot maintain containment
Surgical options:
- Excise lat extruding head portion to stop hinging abduction
- Acetabular (innominate) osteotomy to cover head
- Varus femoral osteotomy
- Arthrodesis
Varus Osteotomy
Late Effects of LCP
- Physeal arrest patterns
- Irregular head formation
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