An inward angle, or neck dry angle, is formed between the femoral neck axis and the femoral shaft axis. The normal value is between 110-140 degrees. The neck dry angle is greater than the normal value of hip valgus, less than the normal value of hip varus.
Congenital hip varus, also known as developmental hip varus, is a deformity caused by progressive reduction of the femoral neck dry angle in young children. Normal adult neck angle is 120 ° ~ 140 °, children 135 ° ~ 145 °. If the neck dry angle is less than 120°, it is called hip varus. It is one of the common reasons for children to behave in a day. There was more unilateral incidence than bilateral, and there was no significant difference in gender and ethnicity.
(1) Causes of the disease
The cause of congenital hip varus is unknown, and many factors may be related to its onset. Some people think that it is a growth disorder, which belongs to a kind of incomplete development of the proximal femur; it is considered to be caused by trauma; others are related to endocrine; it may also be related to family inheritance.
In the fetal development stage, the proximal femoral condyle extends to the upper end of the femur, which is characterized by a crescent-shaped cartilage column, which is quickly divided into the epiphyseal part of the femoral neck and the epiphyseal part of the greater trochanter. The medial part of the femoral neck matures earlier, causing the femoral neck to become longer, while the epiphysis of the femoral head will have an ossification center at 6 months after birth. When the femoral head and neck cartilage are damaged, the lesion is formed by fibrous tissue instead of normal intra-chondral ossification. As a result, the tarsal plate breaks and disappears, often showing a separate triangular bone. As the child walks with weight, it gradually develops into a hip varus.
CT check Nilaton line measurement
The most prominent manifestation of this disease is the growing aggression. The symptoms are not obvious in infants. In the early stage, the main pain was hip pain. After that, the affected limb was weak and fatigued. When walking, the body was shaken and limp. When standing, the affected limb showed external rotation and mild internal retraction. The pelvis was obliquely to the affected side, and the spine showed a convex deformity. The lumbar segment was convex toward the affected side, and the thoracolumbar segment was convex to the healthy side. The affected side of the gluteal muscle was atrophied, the hip line was lower than the healthy side, and the Trendelenburg sign was positive. When the patient is in the supine position, the proliferative femoral head and neck can be reached in the groin. The mega vertex is higher than the Nelaton line, and the hip abduction, internal rotation and extension are obviously limited. The nesting test was negative.
If there is knee pain in children with hip pain, the lower extremity abduction, internal rotation and extension are obviously limited, this disease should be considered. Seen on the features on the X-ray film. Diagnosis is not difficult.
1. Osteochondrosis: The history of osteochondrosis, hip activity limitation and limb shortening are similar to mild congenital hip varus, but both have their own characteristics on X-ray films. There is no separation of bones and neck, the head is dense and flat, and the neck is short and thick.
2. Congenital dislocation of the hip: The claudication of patients with congenital dislocation of the hip occurs earlier, starting from early childhood. Examine the femoral head outside the acetabulum and most patients have a nesting test positive.
3. The disease should be different from hip varus caused by secondary osteophyte spondylolisthesis, avascular necrosis of the femoral head, femoral neck osteomyelitis, multiple osteochondral dysplasia, femoral neck fracture, etc. Gait gait.