1.How does the Pavlik sling work? Pavlik sling is currently the preferred, simple, economical and effective treatment for DDH less than 6 months of age. When wearing the sling, the hip joint is maintained in 90-100° of flexion and <60° of abduction, so that the femoral head slides into the acetabulum with the weight of the lower limb and is maintained in reset to achieve the treatment purpose. When the hip joint is flexed and abducted, the axis of the femoral head points more towards the bottom of the acetabulum, and the acetabulum and femoral head are further fitted closely by their own gravity to promote the joint development of the acetabulum and the femoral head in their compatible relative activities. 2.Is it safe to wear Pavlik sling and what are the risks? If worn properly, Pavlik slings rarely have complications. The more common ones are skin abrasions due to improper care or failure to review and adjust in time; occasionally, femoral nerve palsy can occur due to excessive flexion of the hip joint, which often occurs in more obese children, manifesting as the lower limb on the affected side cannot actively straighten the knee joint, and there is no obvious reaction such as kicking when stimulating the sole of the foot, which can recover on its own after adjusting or removing the sling for a period of time. In addition, the dislocated femoral head may be subjected to mechanical compression by abnormal growth of soft tissues inside and outside the acetabulum during the process of repositioning with the aid of Pavlik sling, and there may be a risk of ischemic necrosis of the femoral head as in other repositioning methods. However, the probability of ischemic necrosis of the femoral head with the application of Pavlik sling is very low. 3.How long do I need to wear the sling? The duration of wear will vary from child to child, depending on the initial development of the hip joint and the responsiveness of the child to the treatment. Generally, as long as the treatment is effective, it should be worn for about 3 months. In a few cases, if the acetabular dysplasia does not improve, it is necessary to extend the wearing time or change to other treatment methods, such as braces. 4.How often should I be reviewed and what tests should I do? For children diagnosed with hip dislocation by ultrasound or clinical physical examination, after the initial wearing of the sling, they need to go to Tianjin Women's and Children's Center once a week to review the ultrasound and have the stability of the hip joint checked by a pediatric orthopedic surgeon to confirm whether the hip joint has been reset. If the hip is successfully repositioned, the child will continue to wear the sling, and the X-ray will be reviewed at 6 weeks and 3 months to further evaluate the repositioning and acetabular development and decide whether to continue wearing the sling depending on the situation. If the acetabulum is still not repositioned at 3 weeks, the patient should be repositioned to another treatment, such as a brace or closed-replacement plaster pants after traction. In the case of acetabular dysplasia or delayed development, the decision to continue wearing the sling will be made after a review of ultrasound at 3 weeks and X-ray at 9 weeks after the initial wear. During the period of wearing the sling, the tightness and angle of the sling should be adjusted every week or two weeks (by a professional technician) according to the growth of the child, in order to maintain the best fixed position and reduce the complications that may be caused by too tight a sling or excessive hip flexion. 5.Why did the doctor ask to change to a brace after wearing the sling? Some of the originally dislocated hip joints are repositioned by wearing a sling, but when they are still unstable (as judged by the doctor based on physical examination or dynamic ultrasound), they need to be changed to a more securely fixed abduction brace or plaster pants to promote the stability of the joint. When the acetabulum is still dysplastic after stable repositioning, treatment should be continued, but the sling is only suitable for children <6 months old because of its relatively weak fixation strength, and as the child becomes fatter, it needs to be changed to a brace for further secure fixation. Moreover, the wearing of the brace is relatively simple, and it is convenient for the family to dismantle and take care of the child in the later stage of treatment. 6.How can we tell whether the sling is suitable for wearing? The sling is mainly composed of two shoulder straps, a chest belt, two hip front side straps and rear side straps. When wearing, the chest belt is at or slightly below the level of the nipple line of the child, and the elasticity is appropriate for a distance of one horizontal finger between the sling and the chest wall; the anterior lateral belt maintains the thigh flexion of about 100°, so that the proximal end of the femur points to the center of the hip joint; the posterior lateral belt maintains the thigh abduction of about 50°, which should not be too tight, and the distance from the knee joint to the center line of the body is about 3 to 5 cm to avoid excessive abduction to reduce the risk of femoral head necrosis. 7.Do I need to wear the sling all day? For dislocated hip joint, it should be worn 24 hours a day in the early stage of treatment because the hip joint has not yet obtained stable reset, and family members should not dismantle it by themselves to avoid affecting the treatment effect due to improper wearing, thus leading to treatment failure. In the middle and later stages of treatment, the hip joint is more stable, and the purpose of continuing treatment is to further promote the development of the joint, so the wearing time can be gradually reduced. However, whether to change to nighttime wear should be decided by doctors with clinical examination and imaging performance, and family members should not change it by themselves, otherwise it may affect the treatment effect and prolong the treatment period. When changing to nighttime wear, the technician will instruct the family on how to put on and take off the sling correctly to facilitate care. For the hip joint that is initially dysplastic, the hip joint is relatively stable, and the doctor will reduce the wearing time accordingly according to the comprehensive judgment. 8.How should the sling be cared for? After wearing the sling, the child should be dressed in loose clothes to prevent clothes or blankets from tangling the bilateral knee joints together, and do not wrap the child in the traditional swaddling method. It is best to wear thin, soft clothing (a T-shirt or undershirt with a collar) under the sling to prevent the sling support from touching the skin, and to wrap the straps in soft fabric to avoid rubbing the neck. Do not put on or take off the sling unless instructed to do so by a doctor. Wash the child's body with a wet towel, but do not take a direct shower. Pay special attention to the hygiene of the skin folds, such as the back of the knee, perineum and inguinal folds, to keep them clean and dry. When wrapping the diaper, make sure to tuck it under the sling to avoid contaminating the sling. If you accidentally dirty the sling, you can wet the area, use a towel or old toothbrush dipped in some soap solution, gently wipe, and let it dry naturally. The tightness of the sling should be easy to put on a finger. It can be slightly tightened after feeding, and can be properly adjusted only when the child's abdomen is bulging. 9.Why can I sometimes feel the hip joint "gada" and "gada" after wearing the sling? At the early stage of treatment, it may be because the hip joint is not yet stable, it can still come out and reset by itself, and the femoral head is constantly moving in and out of the acetabulum and generating elasticity, so the family should avoid repeating the action that can touch the popping sound to avoid damaging the acetabular wall or glenoid lip. In addition, the doctor should be informed during the review so that he or she can further analyze and determine whether the hip joint is repositioned. After the hip joint is stabilized at the later stage of treatment, some children can still sometimes feel the joint rattling when moving, mostly due to the tendons sliding on the joint surface or bone surface. 10.Why did the baby's activity decrease after wearing the sling? The sling only gently restricts the straightening and inward movement of the hip joint. Under normal circumstances, after wearing the sling, the child should be able to further flex and abduct the hip joint on his own, and have the action of kicking and stirring. If the child's lower extremity activity decreases significantly, or if he or she is unable to straighten the knee joint voluntarily, and if there is no obvious kicking response when the sole of the foot is stimulated by extension, he or she should contact the doctor promptly and be alert to the possibility of femoral nerve palsy. This situation is common in children who are fat and have not timely reviewed and adjusted the sling. The fat in the proximal thigh is thicker, and soft tissue accumulates and compresses the femoral nerve when the hip is flexed; it can return to normal on its own after timely detection and adjustment or removal of the sling. 11.When can treatment be stopped? Treatment can be stopped when there is a stable reset of the hip joint and there is no acetabular dysplasia or delayed development of the hip joint. This is mainly manifested by the absence of hip instability on clinical examination, the pelvic X-ray shows that the acetabular roof is flat and has an arc similar to the downward arc of the eyebrows, the acetabular index is within the normal range, and the ossification nucleus of the femoral head is well developed. 12.Do I need to review after stopping the treatment? The hip joint is in a dynamic developmental process until the child matures, so regular review is still needed after treatment to detect possible cases of dysplasia and make timely intervention. 1 week and 1.5 years old, when the baby learns to walk, is the key time to review and evaluate the development of the hip joint. X-rays should be reviewed every one or two years thereafter. The specific time of review should be decided by the doctor through physical examination and imaging performance. 13.Is it normal that the baby's hip and knee joints are not straight after the sling is removed? When the baby is inside the mother's body, the hip and knee joints are kept in a flexed position, which is conducive to the development of the hip joint. The Pavlik sling is consistent with this physiological phenomenon, and the baby's hip and knee may not be straight after wearing the sling for a while, but it will disappear naturally within a few months.