Etiology and associated conditions
Developmental dysplasia of the hip may occur as an isolated condition. In such cases, predisposing factors include fetal breech presentation, oligohydramnios, and female sex (firstborn infants are at higher risk).
Frequently, the pathology is not an independent problem, but is associated with other anomalies. It is important for diagnosticians to assess joint status in patients with torticollis, sternocleidomastoid tumors, and calcaneovalgus foot deformity. The condition may also accompany arthrogryposis multiplex congenita and trisomy 21.
Ultrasound screening
The widespread adoption of ultrasound screening has radically changed the epidemiological picture of the disease. This has led to a significant decrease in the incidence of severe complications, such as bilateral dislocations and the formation of false acetabulae (pseudoacetabulae).
- Procedure: The physician uses a high-frequency linear transducer to obtain a coronal view of the joint. During the scan, the infant lies on their side with the leg flexed and abducted. An important stage of the examination is obtaining dynamic images to assess the position of the femoral head under light stress.
- Interpretation: Result interpretation is strictly age-dependent. A classic example is the Graf classification. If the findings correspond to type IIa (Graf IIa — "immature joint"), this is considered normal up to 3 months of age. A similar sonographic appearance in a child older than 3 months is interpreted as pathological type IIb.
Role of radiography, CT, and MRI
In mild degrees of dysplasia, physical therapy and the use of a Pavlik harness are often sufficient for successful treatment. However, as the child grows, cartilage is replaced by bone tissue, and imaging modalities change.
- Radiography comes to the forefront at 9–12 months of age. During this period, ossification of the proximal femoral epiphysis begins to hinder ultrasound assessment. Radiographs are necessary to evaluate treatment response and for preoperative planning in severe cases.
- CT and MRI are not routine methods. They are extremely useful for accurately assessing the position of the femoral head following surgical reduction if clinicians have lingering doubts.
Important: One of the secondary complications of surgical treatment can be osteonecrosis. However, it tends to have a relatively benign course and does not significantly impair the patient's physical function or quality of life.
To remember the indications for early ultrasound screening, use the mnemonic: Breech presentation, Positive family history, Positive tests (Ortolani and Barlow).
Class and exam questions
At what age is it best to perform an ultrasound examination?
The optimal time for ultrasound screening of the hip joints is considered to be around 6 weeks of age.
Why is ultrasound not used to diagnose dysplasia in children over one year of age?
At 9–12 months of age, ossification of the proximal femoral epiphysis occurs. Bone tissue hinders ultrasound examination, making radiography the primary imaging method.
How does a Graf type IIa joint differ from type IIb?
The difference between type IIa ("immature joint") and type IIb is determined solely by the infant's age. The threshold between these types is 3 months of age.
Why are CT or MRI ordered in cases of dysplasia?
These methods are useful for assessing the position of the femoral head after surgical reduction if the surgeon has clinical doubts about the success of the procedure.
What else to study on this topic
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