Necrosis in deep layer
Cessation of endochondral ossification
Separation from underlying subchondral bone
New accessory ossification
Irregularly hypertrophied articular cartilage
Necrosis of marrow space and trabecular bone
Invasion of vascular connective tissue
Compression fracture of trabeculae
Osteoclastic resorption of necrotic bone
Assymetric appearance of normal bone
Irregularity in the columnisation of cartilaginous growth cells
May extend inferiorly
Growth disturbance apparent
The majority of patients present with mild hip pain of insidious onset, a limp and/or reduced hip movements. Pain is usually activity related and localised to the groin but can be referred to the thigh and knee area.
On examination, an antalgic or Trendelenburg gait may be observed. Hip motion is usually maintained at the early stages but both synovitis and abductor spasm may result in some hip irritability. Initially, hip internal rotation and abduction are limited followed by limitation of other hip movements. During the fragmentation stage, hip motion can become severely restricted with the development of flexion and abduction contractures in some patients. Atrophy of the thigh and calf muscles may be present from disuse, secondary to pain. There may be a leg length discrepancy either from true shortening at the collapsed femoral epiphysis or apparent shortening due to an abduction contracture.
The primary imaging modality for LCPD is plain radiographs; standing anteroposterior and frog-leg lateral views of both hips. These X-rays aid in initial diagnosis, staging of the disease and in providing information about the prognosis.
Additional imaging studies to consider:
Bone scanning may reveal the avascularity of the femoral head in the early stages of the disease.
MRI can detect changes in bone perfusion when X-ray changes are not apparent. However the clinical and prognostic relevance of MRI has yet to be formally defined in the management of LCPD.
Arthrography is useful to assess the shape of the femoral head in relation to the acetabulum and is used to plan surgical management.
LCDP has been divided into four radiographic stages according to characteristic features initially described by Waldenstrom:
Lateralisation of the femoral head.
Decreased size of the ossification centre.
Areas of radiolucency and radiodensity.
This stage lasts about 1 year.
Re-ossification (Healing) Stage:
Bone density returns to normal.
This stage usually lasts 3–5 years.
Residual (Healed) Stage:
Femoral head fully re-ossified.
Remodelling of the head and acetabulum until skeletal maturity.
Four different classification systems have been described:
Based on the amount of capital femoral epiphysis (CFE) involvement on X-rays taken at the fragmentation stage of the disease
Group I – Anterior CFE involvement only
Group II – up to 50% involvement with metaphyseal cysts
Group III – up to 75% involvement with large sequestrum
Group IV – The whole of femoral head involved
Stulberg Outcome Classification
Stulberg outcome classification is determined using both AP and frog lateral radiographs at skeletal maturity (Table 7.2).
Stulberg classification summary
I – Spherical congruency
Completely normal hip joint
II – Spherical congruency with less than 2 mm loss of head shape
Spherical femoral head with a concentric circle on radiographs, with 1 or more of the following abnormalities:
Short femoral neck
Abnormally steep acetabulum
III – Aspherical congruency with greater than 2 mm loss of head shape
Non-spherical (ovoid/mushroom shaped), but not a flat femoral head. With class II characteristics
Mild to moderate osteoarthritis
IV – Aspherical congruency
Flat femoral head with abnormalities of the femoral head, neck and acetabulum
Mild to moderate osteoarthritis
V – Aspherical incongruency
Flat femoral head with a normal neck and acetabulum
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