Developmental dysplasia of the hip (DDH) in children is a common pediatric disease, which refers to the failure of the hip joint to develop normally during the embryonic stage or after birth. If DDH is not detected and treated in a timely manner, it may lead to gait abnormalities, hip joint pain in infants and young children, and even develop into osteoarthritis in adulthood. Therefore, early detection and intervention of DDH are particularly important. In recent years, the application of ultrasound technology in pediatric hip joint examination has become increasingly widespread. Due to its non-invasive, non radiative, and real-time dynamic advantages, it has become an important means of early detection of hip joint development problems. This article will provide a detailed introduction to the principles, indications, examination methods, and early identification of hip joint development issues in children using hip ultrasound.
1、 What is developmental dysplasia of the hip joint (DDH) in children?
Hip dysplasia is a multifactorial disease that includes dysplasia of the hip socket, subluxation of the hip joint, and complete dislocation of the hip joint. The etiology is complex and may be related to the following factors:
1. Genetic factors: Children with a family history of DDH have a higher risk of developing the disease.
2. Fetal position factors: Babies born in a breech position or multiple pregnancies are more likely to develop DDH.
3. Hormonal factors: The maternal relaxation hormone levels are higher in the late stages of pregnancy, which may affect the stability of the fetal hip joint.
4. Packaging method: Binding the baby's lower limbs too tightly during swaddling may limit the normal development of the hip joint.
The clinical manifestations of DDH are diverse. Mild cases may have no obvious symptoms, while severe cases may present with hip joint instability, gait abnormalities, etc. Therefore, early screening and diagnosis are crucial.
2、 Principles and advantages of pediatric hip joint ultrasound
Principles of ultrasound examination
Pediatric hip joint ultrasound examination uses high-frequency sound waves to detect the anatomical structure and dynamic function of the hip joint, mainly used to evaluate the stability of the hip joint, the development of the acetabulum, and the alignment of the femoral head. Ultrasound probes emit high-frequency sound waves, which reflect when they encounter different tissue interfaces. The reflected signals are received by the probe and converted into images. Doctors analyze the morphology and function of the hip joint by observing the images.
The advantages of ultrasound examination
1. Non invasive and painless: Ultrasound examination does not require injection of drugs or exposure to radiation, is non-invasive to infants and young children, and is easily accepted by parents.
2. Real time dynamic observation: Dynamically observing the movement of the hip joint can compensate for the shortcomings of static imaging and provide more comprehensive information.
3. Early screening: Newborns and infants have not yet fully ossified their hip joints, and ultrasound examination can detect hip joint developmental abnormalities earlier.
4. Strong repeatability: Ultrasound examination has no radiation damage and can be repeated multiple times for easy follow-up and observation of treatment effects.
3、 Which infants and young children need hip ultrasound examination?
According to the recommendations of the American Academy of Pediatrics, infants with the following conditions need to undergo hip ultrasound screening:
1. High risk factor infants: late pregnancy with breech delivery, family history of DDH, multiple pregnancies, infants with abnormal hind leg posture (such as unequal legs, limited hip joint movement, etc.).
2. Suspected positive clinical examination: The doctor found abnormalities in the baby's hip joint through physical examination, such as positive Ortolani test (the femoral head can protrude from the hip socket and be reduced), positive Barlow test (the femoral head can protrude from the hip socket), etc.
3. For full-term newborns, especially those born within 2-6 weeks, ultrasound screening is recommended for early detection of problems.
4、 The process and content of ultrasound examination
Preparation before examination
No special preparation is usually required before performing hip joint ultrasound examination. However, it should be noted that the baby needs to be kept quiet during the examination to obtain good image quality. During the examination, the baby is usually placed in a supine position with both lower limbs extended or slightly abducted.
Inspection method and content
1. Static examination: Observe the anatomical structure of the hip joint, including the hip socket, femoral head, joint capsule, etc., through ultrasound. Focus on evaluating the morphology of the hip socket, the alignment of the hip joint, and whether indicators such as the hip socket angle (alpha angle) and hip socket edge angle (beta angle) are normal.
2. Dynamic examination: Observe the stability and range of motion of the hip joint in different positions. For example, by applying gentle pressure, observe whether the femoral head is stably located within the acetabulum, or whether there is displacement and reduction.
3. Result analysis: Through ultrasound images and measurement parameters, doctors can comprehensively assess the health status of the hip joint. The alpha angle of a normal newborn is usually greater than 60 degrees, and the beta angle is less than 55 degrees. If the alpha angle is less than 50 degrees and the beta angle is greater than 60 degrees, it indicates immature hip joint development or the possibility of dislocation, and further observation or treatment is needed.
5、 Early identification and management of hip joint developmental abnormalities
Treatment of immature hip joint development
For infants whose ultrasound examination results show immature hip joint development, conservative treatment can generally be adopted. For example, using Pavlik harness therapy to maintain the hip joint in the optimal position through external fixation devices, promoting normal development of the hip socket and proximal femur. Most infants with immature hip joint development can recover to normal with early intervention, but regular follow-up under the guidance of a doctor is necessary.
The treatment of hip dislocation
Early diagnosis and treatment are particularly crucial for children with hip dislocation detected by ultrasound. Birth to 6 months is the golden period for treatment, which can be corrected through conservative treatments such as Pavlik harness and manual reduction. If conservative treatment is ineffective or treatment opportunities are missed, surgical intervention is necessary. Surgical treatment is complex and the recovery period is long, so early screening is particularly important.
Summary: Ultrasound examination of the hip joint in children is a non-invasive and effective screening tool that can detect hip joint development problems in the early stage and provide a basis for timely intervention. Through active screening and management, the vast majority of DDH patients can achieve a good prognosis. Parents should fully understand the early screening and management of DDH, cooperate with doctors to conduct examinations, and jointly safeguard their children's healthy growth. Only by early detection and treatment can we effectively prevent the occurrence of pain, gait abnormalities, and other long-term complications caused by DDH, and enable children to grow up healthy and happy.