This book describes Perthes Disease, Diagnosis and Treatment and Related Diseases
Perthes disease (also termed Legg-Calve-Perthes) is a rare childhood disorder that involves the proximal femoral epiphysis of the hip.
It normally happens in children who are between 4 and 10 years old.
It happens when the blood supply to the rounded head of the femur (thighbone) is temporarily interrupted.
Without a sufficient blood supply, the bone cells die, a process termed avascular necrosis.
Cause
The cause of Perthes disease is not identified.
Some recent studies indicate that there may be a genetic linkage to the formation of Perthes, but more research needs to be done.
Risk factors
1. Positive family history 10%
2. Low birth weight (less than 2.5 kg in boys)
3. Abnormal birth presentation
4. Second hand smoke exposure
5. Asian, Inuit, and Central European descent
6. Low socioeconomic status
Osteonecrosis happens secondary to interruption of blood supply to femoral head
This is accompanied by revascularization with subsequent re-sorption and later collapse
Creeping substitution supplies pathway for remodeling or healing after collapse
Maternal/passive smoking exacerbates the development of the disorder.
This disorder is a self-limiting process.
There is a inconsistent course to final healing from the first ischemic incident.
This can take 2-5 years to recover.
The disorder is distinguished from adult osteonecrosis by its capability to heal and remodel
While the term "disease" is still utilized, Perthes is really a complex process of different stages that can persist several years.
Stages
1. Initial/necrosis
In this stage of the disease, the blood supply to the femoral head is interrupted and bone cells die.
The region is intensely inflamed and irritated and the child may start to show signs of the disease, such as a limp or different way of walking.
Infarction causes a smaller, sclerotic epiphysis with medial joint space widening.
Radiographs may remain normal for 3 to 6 months.
This first stage may persist for several months.
Fragmentation
Fragmentation starts with evidence of sub-chondral lucent line (crescent sign)
Femoral head seems to fragment or dissolve.
Over a period of 1 to 2 years, the body takes away the dead bone and quickly replaces it with an early, softer bone ("woven bone").
It is during this stage that the bone is in a weaker state and the head of the femur tends more likely to break apart and collapse.
This is the effect of revascularization process with bone re-sorption causing collapse with subsequent patchy density and bone lucencies.
This stage can persist from 6months to 2years.
Re-ossification
New, stronger bone forms and starts to take shape in the head of the femur.
Ossific nucleus goes through re-ossification with new bone showing as necrotic bone is re-sorbed
The re-ossification stage is often the longest duration of the disease and can persist a few years.
Healed
Femoral head heals and remodels until skeletal maturity.
Healing starts once ossific nucleus is fully re-ossified; trabecular patterns re-appear.
In this stage, the bone re-growth is total and the femoral head has achieved its final shape.
One of the earliest signs of Perthes is an alteration in the way the child walks and runs.
The child may limp, have restricted motion, or develop a peculiar running style.
Perthes disease normally restricts the abduction and internal rotation of the hip
Imaging studies are critical in diagnosis and prognosis
The...