Congenital Hip Dislocation

　　1. Genetic factors

　　There is no denying the fact that this condition has a significant family history, especially in twins. The incidence in families with this condition can reach 20-30%, and it is more common among sisters. The same disease can appear in sisters in three types: hip dislocation, subluxation, and maldevelopment. If detailed and early examination and X-ray diagnosis are not carried out, the latter two types are often missed and reach the age of 7 or 8 when the hip joint is completely normal.

　　2. Factors of ligament laxity

　　In recent years, an increasing number of reports have proven that joint ligament laxity is an important factor. In animal experiments, Smith removed the joint capsule and round ligament of a puppy, resulting in a high percentage of hip dislocation phenomena. Clinically, Andren pointed out that the separation of the pubic symphysis on X-ray films in cases of hip dislocation is twice that of normal infants. He believes that this is due to the need for a large amount of endocrine during the process of childbirth, and excessive endocrine changes are an important factor causing hip dislocation. At the same time, Andren and Borglin found that the excretion of estrone (Estrone) and estradiol 17β (Estradil) in the urine of neonates with hip dislocation within 3 days was different from that of normal infants. However, Thieme compared 16 sick infants with 19 normal infants and measured monthly, and after statistical processing, no difference was found. Therefore, the theory that endocrine changes cause ligament laxity has not yet been established.

　　3. Position and mechanical factors

　　In cases of hip dislocation, there are reports that the incidence of breech presentation is as high as 16-30%, while in normal childbirth, breech presentation only accounts for 3%. Wikinson (1963) fixed the infant's hip joint in flexion, external rotation, and straightened the knee joint, and administered estrogen and progesterone, which could lead to hip joint dislocation and malformation.

　　Most complications that occur after the treatment of congenital hip dislocation are mostly due to粗暴的手法, insufficient traction, not mastering the indications for surgery, not understanding the factors hindering reduction and improper fixation, etc., most of which can be avoided.

　　1. Recurrence of dislocation often occurs due to the failure to eliminate factors hindering reduction, the appearance of false phenomena on X-ray, carelessness during the change of plaster, excessive anterior tilt angle, or insufficient development of the acetabulum, thus even after reduction, it is still relatively easy to recur.

　　2. Ischemic necrosis of the femoral head This kind of complication is mainly due to rough manipulation or excessive surgical trauma, which damages the blood supply of the femoral head; strong and extreme abduction during fixation; insufficient traction before reduction or insufficient relaxation of the adductor muscle, psoas muscle, and iliac muscle; excessive pressure on the femoral head after reduction, and some unknown reasons.

　　3. Osteoarthritis of the hip joint is a late complication, usually occurring in older children after surgery, and it is often difficult to avoid some complications after adulthood.

　　4. Separation of the femoral head epiphysis, fracture of the upper segment of the femur, sciatic nerve injury, and other complications are caused by insufficient traction, the use of force during reduction, or too shallow anesthesia. Generally, these can be avoided.

　　1. Limited joint mobility Congenital hip dislocation in childhood is usually characterized by painless and unrestricted joint mobility. However, in the neonatal and infant period, it is exactly the opposite, with temporary joint dysfunction and a certain fixed posture. The typical symptoms are that the child's limbs are in a flexed position and dare not straighten, the activity is worse than the healthy side, and there is weakness. When the lower limb is pulled, it can be straightened, but it will return to a flexed position when the hand is released. A few infants have the lower limbs in an external rotation position, abduction position, or crossed position of both lower limbs, and even the hip joint is completely rigid. Some children cry when the lower limbs are pulled.

　　2. Limb shortening is common in unilateral hip dislocation, with the affected limb shortened.

　　3. Other common symptoms include asymmetry of the labia majora, increased, deepened, or asymmetrical skin creases on the inner side of the buttocks, thigh, or popliteal fossa, widening of the perineum, and sometimes a 'pop' sound or a sense of jumping when the affected limb is pulled.

　　This disease is a congenital disease with no effective preventive measures. Although the time difference between non-surgical treatment and surgical treatment is not much, the efficacy brought to the child is quite different. Therefore, the early detection, early diagnosis, and early treatment of congenital hip dislocation are very critical, and sufficient attention must be paid by parents and doctors, especially in some rural areas. Due to some outdated concepts, some people think that surgery for children is too dangerous or that diseases that will not kill people can be treated later. This leads to a disease that could have been treated for a few hundred yuan being delayed to a later stage, requiring thousands or even ten thousand yuan for treatment, which brings a heavy burden to the patient's family and increases the risk of disability in children.

　　The main reliance is on physical examination, X-ray examination and measurement. Newborns should also pay attention to the following points during examination:

　　1. When multiple malformations with skin creases and hip dislocation are present, the examiner often finds that the proportion of the thigh to the lower leg is not proportional, the thigh is short and thick, and the lower leg is thin and long. The buttocks are often wide, the inguinal creases are short or unclear, and the skin creases on both sides of the buttocks can be seen during the examination. The affected limb usually feels an outward and inward rotation of 15° to 20° and a shortening phenomenon when the limb is flattened.

　　2. The femoral head cannot be felt. With the hip and knee flexed to 90°, one hand holds the upper end of the lower leg, the thumb of the other hand is placed at the inguinal ligament, and the other four fingers are placed at the buttock Shangjiao point. When the hand rotates the lower leg, under normal circumstances, the movement and prominence of the femoral head can be found in front. In the case of dislocation, there is an empty space in front, and the four fingers at the back of the buttocks feel the movement of the femoral head.

　　3. The Galeazzi sign involves lying the child flat, bending the lower limbs to 85°～90° between the knees, and placing the ankles flat and symmetrically. If it is found that the knees are uneven, it is called the Galeazzi sign. This sign is present in all cases of femoral shortening and hip dislocation.

　　4. The Von Rosen line involves the abduction of both thighs by 45～50° and internal rotation, taking an anteroposterior radiograph that includes the upper end of both femurs to the pelvis. Draw a median line of both femurs and extend it towards the proximal side, which is the Von Rosen line. Normally, this line passes through the outer upper angle of the acetabulum; when dislocated, it passes through the anterior superior iliac spine. Before the ossification center of the femoral head appears, it has certain reference value for diagnosis.

　　5. The Shenton line is the curved line at the inferior margin of the pubis in a normal pelvic X-ray, which can be connected with the curved line on the inner side of the femoral neck to form a complete curve, known as the Shenton line. In cases of hip dislocation and subluxation, the integrity of this line is lost.

　　6. X-ray photography of the anterior aspect of the femoral neck may occasionally be needed to further clarify the situation of the anteversion angle. The simplest method is to have the child lie flat, with the hip upward for a pelvic anteroposterior radiograph. Similarly, after the thigh is fully internally rotated, a pelvic anteroposterior radiograph is taken again. By comparing the two films, it can be seen that the full length of the femoral neck appears when fully internally rotated, and the femoral head is clear. When the hip bone is upward, the femoral head overlaps with the greater and lesser trochanters, and the existence of the anteversion angle can be estimated.

　　7. Arthrography is rarely necessary to perform arthrography to clarify the diagnosis in general cases, but in certain situations, it is necessary to clarify the disk-shaped cartilage, synovial stenosis, and the cause of reduction failure. Arthrography may be occasionally necessary under general anesthesia. The hip joint is disinfected and made sterile, and 1～3ml of 35% iodine oil contrast agent (diodonediodast) is injected into the joint anteriorly under fluoroscopy. Under fluoroscopy, it can be found whether there are obstructions at the outer margin of the acetabulum, the condition of the cartilage at the outer margin of the acetabulum, and whether the joint capsule is stenotic. If necessary, re-arthrography can be performed after manual reduction to clarify whether the femoral head has completely entered the acetabulum, the reduction and deformation of the disk-shaped cartilage. Due to the complexity of the operation, insufficient contrast agent filling, and difficulties in reading the film, arthrography for diagnosis has been less commonly used in recent years.

　　8. During the follow-up of central marginal angle (CE angle) cases, it is often necessary to measure the degree of the femoral head entering the acetabulum. Using Wibeng's method, the center of the femoral head is taken as one point, and the outer margin of the acetabulum as another point, connecting these two points to form a straight line. The outer margin of the acetabulum is drawn as a vertical line downward, and the two lines form an obtuse angle at the outer margin of the acetabulum, which is called the marginal central angle. The normal range of this angle is 20～46°, with an average of 35°; 15～19° is suspicious; less than 15°, even negative angle, indicates that the femoral head has moved outward, indicating dislocation or subluxation.

　　Congenital hip dislocation is a congenital disease with an unknown cause. There are currently no effective preventive measures. Generally, there are no special dietary requirements, but it is necessary to ensure a reasonable dietary structure and a nutritious diet as the basic requirement.

　　The treatment methods include closed reduction + stent, closed reduction + frog-like plaster cast; closed reduction + rotational osteotomy to correct the anteversion angle; open reduction, and additional pelvic osteotomy and various osteotomies according to different conditions. The specific treatment principles are as follows:

　　One, from birth to 2 months

　　No traction or anesthesia is required. The hips can be flexed to 90° and then gradually abducted. Place the thumb outside the greater trochanter and push it forward and inward to achieve reduction. It is strictly forbidden to use force during reduction. If the reduction is successful, it can be fixed with a brace at the hip joint flexed to 90° and abducted to 70°, with a fixation time of about 2 to 3 months, depending on the age at the time of reduction. The removal time of the brace should be determined after taking X-ray films. There are many types of braces, such as abduction pillow, Begg plastic brace, etc. The above two types of braces must be opened when changing diapers, which is麻烦 and less commonly used. Barlow brace and Rosen brace are indeed effective, but they exert pressure on the skin, causing pain and pressure sores, and there is a possibility of avascular necrosis of the femoral head. Pavlik brace can avoid complications of avascular necrosis caused by violence. It uses the natural position of the two lower limbs flexed to 90°, the weight of the two lower limbs themselves to achieve abduction, so that it can naturally achieve and maintain reduction, which is beneficial to the development and shaping of the hip joint and has a certain range of hip joint movement. The disadvantage is that it is made of canvas, which is relatively hard. If the bandage around the shoulder and chest is too tight, it affects breathing, and if it is too loose, it is easy to slip off, affecting treatment.

　　Two, more than 3 months

　　For children aged 2 to 3 years, this group of cases has varying degrees of soft tissue contracture around the hip due to a long history of dislocation. Therefore, traction is performed before reduction, usually not exceeding 2 weeks. If there is significant muscle contracture, it is necessary to perform release before reduction, such as incision of the adductor muscle, extension of the iliac-psoas muscle, etc. After confirming the position of the femoral head at the level of the acetabulum through bedside X-ray, reduction under general anesthesia is performed. If the position after reduction is satisfactory, the frog-type plaster cast is used for fixation. In order to meet the needs of children's growth and development, the cast is changed every 2 to 3 months, and an X-ray film is required each time to confirm the position of the femoral head in the acetabulum. If it is found that the dislocation occurs again after changing the cast, it must be reduced again. Each time the cast is changed, the thigh is gradually adducted until the development of the acetabulum is normal, and then the cast fixation can be removed. If reduction fails, it should be considered that there may be hyperplasia of fatty fibrous tissue in the acetabulum, hypertrophy of the round ligament, and dumbbell-shaped joint capsule, which hinder the entry of the femoral head into the acetabulum, so open reduction is required.

　　Three, 3 years old to 8 years old

　　The children in this group have a long history of dislocation, with more obvious soft tissue contracture, poor acetabular development, often small and shallow, and a large amount of fatty fibrous tissue at the bottom of the acetabulum. Manual reduction is extremely difficult, so the vast majority of cases require open reduction. However, before open reduction, traction must be performed for 2 to 3 weeks until the femoral head is tractioned to the level of the acetabulum, then surgical treatment can be performed. If it cannot be tractioned to the level of the acetabulum, it indicates that there is significant soft tissue contracture. If open reduction is performed at this time, there is a high possibility of avascular necrosis of the femoral head, so soft tissue release must be performed first, followed by traction. After open reduction, additional rotational surgeries can be performed according to different conditions, such as:

　　Four, femoral head covering surgery

　　Generally applicable to children with semi-dislocation, poor acetabular development, and the femoral head cannot be completely covered. There are mainly three types of surgery for this kind of condition:

　　1. Pelvic osteotomy (Salter surgery): Good reduction is required before the operation. If manual reduction is difficult, open reduction must be performed during the operation, and then the pelvic osteotomy is performed. During the operation, the lower osteotomy slice must be pulled forward and downward to increase the coverage area of the femoral head and the stability of the hip joint.

　　2. Pelvic osteotomy frame surgery (Chiari surgery): This surgery must be performed on a traction bed and equipped with X-ray monitoring. The positioning must be accurate, and the attachment points of the joint capsule must be identified clearly. There is a risk of sciatic nerve injury during the operation, and there are also many opportunities for contamination during the operation, so currently this method is used less.

　　3. Pericapsular osteotomy (Pemberton surgery): This surgery makes the superior part of the acetabulum anterior and laterally folded, increasing its coverage area. A bone slice is taken from the ilium and inserted into the opened osteotomy site to stabilize the reconstruction of the acetabulum. The cast is fixed after the operation.

　　V. Zahradnick Surgery

　　1. First perform open reduction and deepen the acetabulum. After reduction, due to the large anterior tilt angle of the femoral neck, the lower limb must be in an extreme internal rotation position to achieve reduction, so it is necessary to perform rotational osteotomy below the trochanter and then fix it with a plate and screws. After the operation, the leg is immobilized with a cast, and the front half of the cast is removed after 4 to 6 weeks to exercise the hip joint flexion and extension functions, and it is continued to be immobilized at night. X-ray examination of the osteotomy site for healing, and can get out of bed for functional exercise.

　　2. For children over 8 years old, it is generally difficult to perform open reduction and there are many complications, so it is generally not recommended to perform open reduction, but to use some conservative surgeries aimed at stabilizing the hip joint, such as acetabular osteotomy with bone grafting and femoral neck osteotomy. In recent years, the application of shortening the femur for re-reduction has shown short-term efficacy.

　　3. For adult congenital hip dislocation, it is generally more common in postpartum women and mostly in subluxation. Due to long-term weight-bearing under abnormal hip joint conditions, it is easy to cause traumatic arthritis, causing hip joint pain. For such cases, it is generally recommended to cut the obturator nerve to temporarily relieve pain. If it has affected the function of the hip joint, artificial total hip joint replacement surgery can be applied.