【Overview】.
A relatively common malformation of the hip joint, characterized by partial but rarely complete detachment of the femoral head from the acetabulum in infants at birth. The lesion involves the acetabulum, femoral head, joint capsule, and the ligaments and muscles surrounding the hip joint. There are two types of the disease, namely typical congenital hip dislocation and teratogenic hip dislocation. The latter is rare and is a malformation of the embryonic organ during growth, often combined with other malformations such as congenital polyarticular contracture congenital vertebral hemivertebral malformation and other syndromes. This section only discusses typical congenital hip dislocation.
Etiology and pathogenesis
The cause is unknown so far.
1, genetic factors According to the incidence of congenital hip dislocation and geographical and racial closely related, there is often a family history, more girls than boys, suggesting that the disease is related to genetic factors.
2, acetabular dysplasia and joint capsule, ligamentous laxity factors as the main pathogenic factors Typical congenital hip dislocation children, in the fetal period and after birth, only the acetabulum shallow flat, the top of the socket dysplasia, joint capsule laxity and other pathological changes. As children grow older, some of them develop complete hip dislocation. Statistics on clinical cases confirm that acetabular dysplasia is three times higher than complete hip dislocation.
Laxity of the hip capsule and ligaments often coexists with acetabular dysplasia. Laxity of the hip capsule and ligaments is more common in female infants, which is consistent with the higher incidence of congenital hip dislocation in females than in males. It has been shown that female infants have higher levels of estrone production than male infants. Estrone is metabolized in the infant or neonate into estradiol, which is excreted in the urine. Estrone and estradiol 17-beta have a strong pelvic, joint capsule, and ligament relaxing effect. This proves that the imbalance of female gonadal hormones is also a factor in the pathogenesis of pelvic and hip ligament laxity and congenital hip dislocation.
Other scholars believe that acetabular dysplasia is a secondary lesion of hip dislocation and is not the cause of hip dislocation. If hip dislocation or joint laxity is treated in time, acetabular dysplasia can be restored to normal.
3, mechanical factors The fetus in the uterus is always under the pressure of the uterus, abdominal wall muscles, amniotic fluid and placenta, if the fetal position and the amount of amniotic fluid are normal, these pressures do not affect the development of the fetal hip joint. On the contrary, if the fetus is in breech position (especially in extended leg breech position), with little amniotic fluid and abnormal placental position, the hip joint may be subjected to abnormally high pressure, which may change or even destroy the normal anatomical relationship of the hip joint and affect the development of the hip joint, resulting in congenital hip dislocation.
Diagnostic points】
Clinical manifestations
Varies according to age.
1. Pre-standing The symptoms are mild and can be manifested as.
(1) Widening of the perineum, more pronounced in bilateral cases, contracture of the affected femoral adductor muscle.
(2) Limb shortening: shortening of the lower limb on the affected side, making the inguinal stripe deep and high in position. The skin folds of the hip and inner thigh are asymmetrical, and the skin lines on the affected side increase and deepen compared to the healthy side.
(3) Restriction of hip movement on the affected side: the earliest and more reliable sign. The affected side is often in the flexed position, unwilling to straighten, weak, can be straightened when pulling, and then flexed again after releasing, or can be in the straightened external rotation position, or the two lower limbs are in the crossed position. The amplitude of external rotation on the affected side is reduced to 15°~20°, and the hip abduction is limited when the lower limb is in extension or flexion position. There is a history of crying when the affected limb is tugged. The pedaling force is weak. The lower limb on the healthy side moves freely.
(4) When the lower limb on the affected side is pulled, there is a popping sound or popping sensation in the hip joint area.
(5) Knee flexion and hip flexion and abduction test: after each hip and knee is flexed to 90°, the two hips can be abducted to 70°~80°. If it is less than 60°, it is positive (+). If the hip joint can be abducted to 90° after hearing the popping sound, it means the dislocation has been reset. The examination must be performed on both sides simultaneously to fix the pelvis and to facilitate comparison between the two sides. If the hip activity is limited and the abduction test is positive, this disease should be considered.
(6) Galeazzi’s sign: when the child lies on his back and flexes the hip and knee at 90°, the affected knee is lower than the healthy knee because the hip dislocation shortens the affected thigh, which is called positive Galeazzi’s sign, which is only applicable to unilateral patients and not to bilateral ones.
(7) Ortolani’s test and Barlow’s sign: The infant lies supine and the assistant fixes the pelvis. The examiner’s thumb is placed on the medial thigh and the other
fingers are placed on the lateral aspect of the greater trochanter of the femur. The hip is first flexed at 90°, then the hip is gradually abducted and the greater trochanter is pushed anteriorly and medially with the four fingers. At this point, the examiner can feel the popping or beating sound of the femoral head sliding into the acetabulum, which means a positive Ortolani test. A positive result indicates a possible dislocation that is not yet a dislocation, so the diagnosis is an unstable hip, or a positive stability test.
These two signs are done simultaneously in a single examination and are repeated several times. These two signs are most reliable and typical in the neonatal period, because newborn infants have low muscle tone, which easily elicits this sign, and therefore, it is not appropriate for children older than 3 months. However, when a child is crying, moving around, or has an inotropic muscle contracture, this sign can be negative despite dislocation. Therefore, a negative result does not exclude dislocation.
2.Standing and walking period Lameness (unilateral) or “duck walk” (bilateral), i.e., with each step, the trunk tilts toward the weight-bearing side, also known as Trendelenburg gait.
(1) The hips are flat and wide, and the femur is protruding. If the dislocation is bilateral, it is manifested by widening of the perineum, posterior shrugging of the hips, increased lumbar pronation, and protruding hips. The pelvis is tilted forward.
(2) The femoral triangle on the affected side is hollow and depressed, and the femoral artery pulsation is weak. The hip abduction is limited and the adductor muscles are tense.
(3) The examiner places one hand on the large thick ridge of the upper femur on the affected side and passively rotates the affected limb with the other hand, and can feel the dislocated femoral head slide.
(4) Galeazzi’s sign is positive.
(5) Telescoping’s sign: when the affected limb is pushed and pulled, the femoral head can move up and down, like a “pump” or “telescope”, which is positive.
(6) Trendelenburg sign: when standing on one leg, the pelvis on the opposite side drops, which is positive, suggesting that the hip abduction on that side, especially the gluteus medius, is weak. If the gluteus medius is paralyzed or the distance between the iliac crest and the greater trochanter is shortened and the contralateral pelvis cannot be lifted, it is called a positive Trendelenburg test. When walking, a duck walk occurs.
(7) Most of them have no symptoms of hip pain, and often complain of fatigue and weakness of the hip. As they grow older, some children complain of pain in the hip and lower back. The affected limb has mild muscle atrophy, pelvic tilt, and scoliosis.
Imaging
The diagnosis is not difficult in typical cases. After the child starts walking, he or she shows a limp or swaying gait, which is easily noticed by parents, but it is too late for diagnosis. The clinical manifestations are very atypical in the neonatal period, and the diagnosis is easily missed if the examination is not careful. The diagnosis of neonatal hip dislocation should also pay attention to the child’s birth, fetal position, place of birth, family history and so on. For children with suspected hip dislocation, pelvic X-ray should be taken 4 months after birth to clarify the diagnosis.
X-ray examination plays an important role in the diagnosis, but sometimes it is not decisive for the diagnosis of hip dislocation in newborns. Therefore, it is best to take an orthopantomogram of the pelvis including both hips at 4 months after birth. The correct pelvic radiograph should be taken with the lower extremities straight and together and with both hips flexed at 30°. The following changes should be noted when determining whether there is a hip dislocation.
(1) Acetabular index (also called acetabular angle); the acetabulum in children is composed of the iliac bone, pubic bone and sit bones connected, i.e. Y-shaped cartilage. Normal should be less than 30°. Greater than 30° indicates acetabular dysplasia. This means that the acetabular fossa is shallow, and even if the ossification center of the femoral head is still in the acetabulum there is still the possibility of dislocation later.
(2) Measure the distance between the midpoint of the proximal femoral epiphysis and the pelvic level (Hilgenrheiner line) and the acetabular floor (D-line): in this age group, the Hilgenrheiner line does not exceed 1 cm and the D-line does not exceed 1.2 cm in normal individuals.
(3) Perkin’s square: the acetabulum was divided into four zones. Under normal circumstances, the ossification center of the femoral head is within the inner inferior zone, and if it is beyond this zone, it is classified as subluxation or dislocation depending on the degree. In newborns and infants, the femoral head cannot be measured because the femoral head bones are mostly absent. The relationship between the rostral process of the femoral neck and the Perkins line can be observed. In a normal hip, the rostral process of the femoral neck is medial to the Perkins line and outside of it in the case of dislocation.
(4) Shenton’s line: the superior edge of the foramen occulans and the inner edge of the femoral neck can be connected into a complete arc-shaped curve, called Shenton’s line or cervical foramen occulans line, which is interrupted in case of dislocation.
(5) Simmon’s line: A continuous arc from the lateral edge of the ilium to the upper outer edge of the acetabulum, downward and outward, along the outer edge of the femoral neck. In dislocation, this line is interrupted.
(6) Ponseti-Y coordinate: a vertical line drawn from the ossification center of the femoral head to the midline of the sacrum. If the lengths of the two sides are unequal, there is dislocation on the longer side. If the ossification center of the femoral head has not yet appeared, a horizontal line can be drawn from the apex of the medial femoral neck to the outer edge of the “teardrop”, and the degree of dislocation can be estimated according to the difference in the length of the distance.
(7) CE angle: It is the angle of intersection between the Perkin line and the center of the femoral head to the outermost edge of the acetabulum, also known as the Wiberg angle, which is normally 20°~40° inward.
(8) The ossification center of the femoral head is smaller than the healthy side due to developmental effects.
(9) Increased anteversion angle of the femoral neck on the affected side: the shorter the femoral neck, the greater the anteversion angle. The easiest way to measure the anteversion angle is to place the child in a prone position and place the hip in different angles of internal rotation under the control of an image intensifier until the longest femoral neck is obtained, and measure the angle of internal rotation, i.e. the degree of anteversion angle.
(10) During the standing and walking period, the stem angle of the femoral neck was greater than 135°. The upper part of the bony acetabulum loses its normal curved (arch) structure and becomes sloped, and the femoral head epiphysis develops and the sitting pubic arch association is slower than that of the healthy side.
X-ray examination can determine the nature and extent of the dislocation. According to the relationship between the dislocated femoral head and the acetabulum, it can be divided into supra-acetabular dislocation and post-acetabular dislocation. The former generally forms a secondary bony depression on the iliac bone above the acetabulum, called a “false acetabulum”, while the latter is not obvious. There are three types of dislocation depending on the height of the superior femoral displacement.
① congenital hip dysplasia: the femoral head is slightly displaced outward, the Shenton line is basically normal, but the CE angle may be reduced, and the acetabulum is shallow, which is classified as Dunn class I.
(2) Congenital hip subluxation: the head of the femur is displaced outward, but still forms an articulation with the lateral side of the acetabulum, the Shenton line is interrupted, the CE angle is less than 20°, and the acetabulum is shallow, which belongs to Dunn classification grade II.
(3) Complete dislocation of the congenital hip joint: the femoral head leaves the true acetabulum and forms an articulation with the lateral surface of the ilium, then a false acetabulum is formed, and part of the original joint capsule is embedded between the head and the socket, which belongs to Dunn classification grade III.
Hip arthrography can observe the size and shape of the femoral head, the cartilage margin of the acetabulum, the annular region, the transverse ligament, and the round ligament. If the hip is dislocated and there is inversion of the glenoid rim, there may be a filling defect between the femoral head and the acetabulum, significant contraction of the joint capsule, and a banding shadow in the acetabulum, indicating a hypertrophic round ligament.
The diameter of the femoral head and the coverage of the femoral head in the acetabulum become smaller on ultrasound, the vertical distance from the greater trochanter to the acetabular floor becomes longer, and the acetabular angle becomes larger. Compared with traditional X-rays, B-ultrasound examination results are accurate, and non-invasive, no radiological damage, clear visualization, and can display the hip structure in multiple planes and levels, which has the advantages that X-rays cannot replace in the diagnosis of hip dislocation in infants and children. It is an important and reliable means for early diagnosis of congenital hip dislocation.
CT and MRI can see that there is a defect in the posterior situs, which deforms the acetabulum and causes dislocation, and can observe bone changes, soft tissue embedding and anterior femoral neck inclination angle as well as the degree of dislocation of the femoral head.MRI examination can also observe deformation, thickening and displacement of acetabular cartilage.
In the early diagnosis of congenital hip dislocation, since the articular cartilage and soft tissues cannot be visualized on X-ray plain films and can only rely on indirect measurements, their value is very limited and the rate of missed diagnosis is high. CT is similar to X-ray and cannot differentiate between femoral cartilage and adjacent soft tissue structures until the ossification center within the femoral head appears. Both are radioactive hazards to infant gonads and cannot be observed dynamically, so they are not suitable for the diagnosis of neonatal hip dislocation.
MRI can accurately display the hip cartilage and soft tissues and understand the pathological changes of the hip joint, but MRI cannot be observed dynamically, is expensive, and is difficult to repeat the examination for many times. However, MRI cannot be used for dynamic observation, is expensive, and is difficult to repeat several times. MRI is also of limited value in children because they must be sedated before examination. Since the use of ultrasound to diagnose hip dislocation in the 1980s, it has been used all over the world because of its ability to show the cartilaginous femoral head, direct static or dynamic observation of the three-dimensional relationship between the head and socket and the stability of the hip from different angles, early and clear diagnosis of hip laxity, acetabular dysplasia, hip subluxation and dislocation, no radiological damage to the pediatric population, convenient examination, rapid diagnosis, economy and high repeatability. It is widely used and can be used as one of the newborn screening programs.
【Overview of treatment
Different treatment methods should be used at different ages, and the general principle is early diagnosis and early treatment. The main treatment is to release the disorder of the iliopsoas muscle, which is more important than the factor of the adductor muscle, especially in the early stage. non-surgical treatment should be mainly used for children under 3 years old, i.e., closed repositioning and stabilization of the repositioned hip joint with external fixation brace. surgical treatment should be mainly used for children over 3 years old.
1, newborn (within 6 months) The principle of treatment is to keep the two hips in the external booth for a long time, reset the femoral head, so that the posterior upper edge of the acetabulum and the femoral head develop normally, so that the joint is stable and does not dislocate again. The commonly used methods are Pavlik brace, Von Rosen brace or simple soft brace such as abduction pillow to keep both hips in flexion and abduction position, which can be cured in 6~8 weeks. The advantages are that it is simple and easy to maintain the hip flexion and abduction position and allows a certain range of motion of the hip joint, which is beneficial to the development of the hip joint and reduces the incidence of ischemic necrosis of the femoral head.
The Pavlik brace is composed of a chest strap, two shoulder straps and two stirrups. When using the Pavlik brace, attention should be paid to the possibility of aseptic necrosis of the femoral head. Pavlik braces should not be used in cases of teratogenic dislocation. After the use of the retractor, the Barlow test is performed to test its stability. If the dislocation persists for 6 to 8 weeks, the Pavlik retractor should be discontinued in favor of other methods, including traction, closed revision, and cast immobilization, and the Pavlik retractor should be continued until the Barlow test is negative, i.e., stability has been achieved. During this time, the brace should be checked once a week and the band adjusted as the child grows. If it is stable, it can be removed once a week for bathing.
The duration of treatment depends on the age at diagnosis and the degree of hip instability. For example, the duration of brace wear should be equal to the age at stabilization plus 2 months. At the beginning, the brace should be removed for 2 h per day and doubled every 2-4 weeks until the x-ray shows a normal hip joint.
2, infants (6~12 months) The principle of treatment at this age will be mainly closed repair, if it fails, it should be cut and repaired, traction should be performed before the manual reset, and external fixation should be used to keep the joint stable after the reset.
(1) Traction: skin suspension traction of both lower limbs in hip flexion should be done for 2~3 weeks before the reset. During continuous skin traction, both lower limbs should be gradually abducted.
(2) Manipulative repositioning: the child is placed in a supine position, the assistant fixes the pelvis, and the thumb of one hand of the operator is placed in front of the iliac wing, and the other four fingers are placed behind the greater trochanter of the femur. The other hand holds the knee joint of the child and flexes the hip until the front of the thigh is in contact with the abdominal wall. In this way, the thigh flexors are completely relaxed and the femoral head is displaced from high to behind the posterior edge of the acetabulum. Then the affected leg is moderately abducted and externally rotated, as if an arc is turned 90° from the sagittal flexion position and into the external booth of the frontal plane, so that the head of the femur is close to the posterior edge of the acetabulum.
Then apply traction and downward abduction pressure on the longitudinal axis of the thigh, these two forces should be gradually strengthened, do not use violence; while the other finger pressed on the femoral trochanter should apply upward counter pressure, the femoral head can be forced to jump over the posterior edge of the acetabulum and incorporated into the acetabulum. When you feel the bouncing sensation of the femoral head re-entering the acetabulum, it means that the reset is successful. Then both hips are abducted and fixed in frog position. The ideal position is 95° of flexion and 45°~70° of abduction.
Excessive abduction can lead to compression femoral head necrosis due to excessive pressure between the dislocated femoral head due to the pulling of the adductor muscle group. The duration of fixation is usually 3 months, and X-ray examination should be performed in the 1st and 6th weeks after repositioning. After release of external fixation, to promote the development of the acetabulum should be replaced with a double lower limb abduction internal rotation cast or brace for another 3 months. During the braking period, the hip joint should be actively or passively flexed and extended to promote its growth and development.
(3) Internal adductor cut: For those cases with femoral head dislocation over 3 cm and severe contracture of the internal adductor muscle group, part of the starting point of the internal adductor muscle and the stop of the iliopsoas muscle should be cut, followed by traction or closed repositioning.
(4) Incisional revision: If the manual revision fails, incisional revision should be considered to remove the obstructing soft tissues so that the femoral head can be placed into the acetabulum.
(1) Anterior approach to the hip joint (Somerville method): suitable for infants and children with little upward dislocation of the femoral head and no obvious bony secondary lesions in the acetabulum. After 8 weeks of postoperative fixation, the patient can then move freely in bed.
(2) Medial hip joint access incision and repositioning (Ferguson method): the same indications as Somerville method. After surgery, the hips are fixed in flexion 10°, abduction 30° and internal rotation 10°~20° with double hip herringbone plaster type and maintained for 4 months.
(5) External fixation: Hip herringbone cast is preferred. Other external fixation apparatus can also be used, such as plastic support with the advantages of being shaped according to the shape of the child’s pelvis and the required hip flexion and abduction angle and not affecting the X-ray examination. Regardless of the type of brace, the basic requirement is to keep the hip joint flexed and abducted.
3, 1~3 years old Children are mostly standing and walking with weight, and the dislocation is more obvious, but the pathological changes are not yet fixed, so non-surgical treatment is still the main treatment.
The main treatment is non-surgical, including traction, manual repositioning and external fixation. In cases of severe contracture of the adductor muscles, an adductor muscle amputation should be performed.
The duration of external fixation in children aged 1 to 3 years is usually 6 to 9 months after repositioning, with replacement every 3 months and review of radiographs to understand the repositioning situation. After the external fixation is removed, the child should be given functional exercises of the hip and knee joints to restore both hips to functional positions. If the anterior tilt angle of the femoral neck is greater than 30°, the lower extremities should be fixed in an abduction and internal rotation cast for 3 months. If the excessive anteversion angle is still not corrected after the cast is removed, the patient can continue to follow up and observe for about six months before deciding whether to perform external rotation osteotomy of the upper end of the femur.
In children, the anteversion angle of the femoral neck varies with age, and the younger the age, the greater the anteversion angle. The anterior tilt angle is about 30° at birth and about 10° in adults. Too much anterior tilt is enough to cause hip dislocation or subluxation, so it is important to pay attention to this problem when treating hip dislocation. Currently, CT can be used to determine the anteversion angle.
Children with no obvious hip dysplasia who have failed manual repositioning should undergo early incisional repositioning. It is not necessary to perform a major surgery, but rather a simple incisional repositioning to remove the obstructing factors (such as the tense iliopsoas muscle). The Somerville method or Ferguson method can be used.
In children with hip dysplasia, an incisional revision and femoral osteotomy or pelvic osteotomy should be performed. This includes proximal femoral osteotomy to correct, such as the MacEwen osteotomy and Shands osteotomy, Waguer’s lamellar splinting procedure or Lioyd-Roberts et al.’s tension screwing. If the primary dysplasia is in the acetabulum, Salter’s iliac osteotomy may be performed. If the deformity occurs on both sides of the joint, osteotomy of the femur and pelvis should be done.
(1) Femoral osteotomy
(1) Reverse rotation osteotomy of the distal femur (Crego method): after osteotomy, keep the proximal end in the internal rotation position and externally rotate the distal end, so that the knee, ankle and foot are in line with the anterior superior iliac spine, and apply a unilateral hip herringbone cast. The steel pin was wrapped in the cast along with the traction arch. The cast was removed 2 months after surgery.
② Proximal femur inversion counter-rotation osteotomy (MaoEwen and Shands method): after osteotomy, the distal end was internalized to maintain bone surface contact and correct angulation and rotation. Insert the screw and fix it with a hip herringbone cast, with the Sears pin wrapped in the cast.
(iii) Controlled osteotomy with tensioned screws and splints (LloydRoberts): internal rotation of the hip joint, subtrochanteric osteotomy and splint fixation. After the operation, the hip was fixed in herringbone cast for 6~12 weeks, the cast was removed, and the hip joint was exercised, and then weight-bearing was gradually started.
(2) Pelvic osteotomy: whether done simultaneously with osteotomy or alone, it can help to enhance the stability of congenital dysplasia or dislocated joints. It can be combined with femoral osteotomy to correct valgus deformity or anteversion angle of the femoral neck, or shorten the femur to achieve dislocation revision without adverse pressure on the femoral head.
① Iliac osteotomy (Salter’s method): for subluxation or subluxation that has been rectified, or repositioned with an incisional rectification at the same time as the osteotomy. The age is 18 months or older. It is also indicated in cases where the femoral head cannot be completely covered, such as in children, adolescents and young adults with cerebral palsy, anterior spinal cord poliomyelitis, spinal meningeal bulge or Perthes’ disease. The procedure allows the entire acetabulum, together with the pubic and sit bones, to rotate together as a unit, using the pubic symphysis as a hinge. The osteotomy is opened anterolaterally and propped up with a wedge-shaped bone block, so that the acetabular roof can be moved forward and outward to better cover the femoral head.
Preoperative requirements: first, the femoral head should be traction to below the level of the acetabulum; second, the contracture of the iliopsoas and adductor muscles should be fully released; third, the femoral head should be completely up to the center of rectification to the depth of the true acetabulum; fourth, the joint surface should be fairly flat and free of degenerative arthritis; fifth, the hip joint should function normally; and sixth, the age of the original treatment for patients with congenital hip dislocation should be between 18 months and 6 years. The age of surgery for subluxation, residual or recurrent dislocation or subluxation can be reached early in life. If the above requirements are not met, Salter surgery is contraindicated. salter surgery can achieve good results and is simple if the indications are chosen correctly and the operation is performed without errors. Currently, this procedure is recognized and widely used by orthopaedic surgeons worldwide. Therefore, for children within this age group, the
This procedure is preferred.
(2) Acetabularplasty or paracapsular iliac osteotomy (Pemberton’s method): It can only be used in cases of subluxation or dislocation that has been repaired or can be repositioned by incision and repair. Age 1 to 12 years. The operation is performed via an iliac osteotomy above the acetabulum, using the Y-shaped cartilage of the acetabulum as a hinge to rotate the acetabular roof forward and outward. After surgery, the hip is fixed in a unilateral herringbone cast for 8 to 12 weeks.
The advantages of the parietal iliac osteotomy of the hip capsule are that it does not require internal fixation, it can avoid reoperation, the degree of correction is greater and the rotation is not too great, but the operation is more complicated and the incidence of aseptic necrosis of the femoral head is higher. The operation is limited by the mobility of the Y cartilage, and it is easy to cause premature epiphyseal closure with this cartilage as the hinge. Surgery changes the shape and increases the capacity of the acetabulum poorly, and the relationship between the acetabulum and the femoral head can occur incomplete alignment, and the acetabulum must be reshaped, while iliac osteotomy does not change the shape of the acetabulum, so there is no need to reshape it.
(③Osteotomy for free acetabulum: It is a partial freeing of the pelvis to produce a free segment including the acetabulum.
④Shelf-building surgery: used for hallux valgus, this is a procedure that extends the acetabular roof outward and backward or forward. This can be done with bone grafting or by turning the acetabular roof and part of the lateral iliac bone cortex above the femoral head downward. For irreparable dislocations, a bone vault can be made on the lateral iliac bone over the femoral head.
⑤ Iliac osteotomy and intra-acetabular displacement: This is a modified frame-building procedure in which osteotomy is performed on the proximal side of the acetabulum to displace both the femur and the acetabulum medially, deepening the dysplastic acetabulum and improving the coverage of the femoral head superiorly and laterally.
4.3~7 years old With the increase of age, the secondary lesions of congenital hip dislocation increase, and the success rate of closed repositioning is only 2.38%. Even if the reset is successful, various complications occur in 50% of these cases. Therefore, surgical treatment should be the main method, and the specific choice of surgery should be determined according to the degree of lesion, individual differences, the indications, advantages and disadvantages of each surgery. However, the following measures must be taken in the treatment, no matter which surgery is done.
(1) Adequate bone traction of the affected limb before surgery, the traction weight should be about 13% of body weight for 3~5 weeks, and the lower limb should be kept in a functional position during traction. If necessary, part of the adductor muscle can be cut first, and then traction can be performed.
(2) Thoroughly loosen the soft tissues around the hip joint and perform shortening osteotomy of the upper femur, which causes shortening of the pelvic thigh muscles due to the upward shift of the femoral head. Therefore, these muscles must be thoroughly released during surgery, such as cutting off the adductor muscles, iliopsoas muscle, and the gluteus medius stop stripping. For older children with high dislocation of the femoral head, simple soft tissue release cannot relieve the pressure between the femoral head and the acetabulum, so a shortening osteotomy of the upper femur should be performed at the same time, which is equivalent to relatively lengthening the contracted muscles with good results, and the length of shortening should be within 2 cm if the hip dislocation is unilateral, and should not exceed 3 cm if bilateral.
(3) Remove the diseased tissues in the acetabulum, including fibrofatty tissue, remove the elongated and hypertrophied round ligament, the hyperplastic synovial membrane at the edge of the acetabulum, fibrous tissue and the transverse acetabular ligament, and restore the normal volume of the acetabulum. Protect the articular cartilage surface, unless there is a serious disproportion between the femoral head and acetabulum such as an oversized femoral head or a narrow acetabulum, the acetabulum should not be easily enlarged and the articular cartilage surface should not be damaged.
(4) Correction of excessive anterior femoral neck inclination, if the anterior femoral neck inclination is greater than 30°, it must be corrected by rotational osteotomy under the femoral trochanter, and it is generally appropriate to correct the anterior femoral neck inclination to 10°.
(5) Correct the bony lesion of the upper part of the acetabulum, so that the slope of the upper part of the acetabulum is restored to an arc, and the slope of the top of the acetabulum, the pressure on the surface of the joint is concentrated, which easily leads to joint degeneration.
(6) Firmly suture the joint capsule, the stability of the hip joint after incision and repositioning mainly relies on firmly suturing the joint capsule to maintain. The adhesions of the joint capsule to the iliac bone above the acetabulum and to the surrounding muscles should be stripped first. The excess joint capsule tissue should then be removed and the joint capsule, especially above the acetabulum, should be overlappingly sutured, otherwise the femoral head is prone to re-dislocation after surgery.
For this age group the following surgical approaches are available.
① Incisional repositioning and femoral shortening (Klisic and Jankovic method): combined incisional repositioning and femoral shortening, followed by acetabular surgery such as Salter iliac osteotomy or Pemberton acetabularplasty if needed. It can be used for both unilateral and bilateral dislocations. After surgery, the hip is immobilized in a herringbone cast to maintain the affected limb in an abducted and rotated neutral position. The cast can be removed about 2 months after surgery. Physical therapy and exercises are available, but weight-bearing should be allowed only after 4 months. In case of unilateral dislocation, unequal lower limb length can be seen.
②Osteotomy of free acetabulum: for older children with residual dysplasia and subluxation, and the acetabulum cannot be reshaped.
③Staheli surgery: Staheli surgery is indicated for cases of acetabular dysplasia that cannot be corrected by steering pelvic osteotomy. After surgery, the hip is fixed in a hip herringbone cast in 15° abduction, 20° flexion and neutral rotation. the cast is removed after 6 weeks and weight bearing after 3 to 4 months.
Chiari surgery is an arthroplasty procedure that involves osteotomy of the iliac bone at the superior edge of the acetabulum outside the joint to allow the acetabulum to move inward, and is suitable for patients over 4 years of age, including adults, who have a disproportionate femoral head and acetabulum, a shallow acetabulum, a large femoral head, a portion of the femoral head not covered by the acetabulum, and no other indications for surgery. to correct the outward displacement of the femur. A pelvic osteotomy is performed at the superior border of the acetabulum, and the pelvis below the osteotomy is internally displaced along with the femur. The upper part of the osteotomy becomes the skeleton and the joint capsule is embedded between the upper part of the osteotomy and the femoral head. Technical errors are excessive internal displacement, osteotomy too high or too low, and sciatic nerve injury.
The hip cast is fixed in 20°~80° abduction, neutral rotation and extension position. 3 weeks later, the cast is removed and exercise is started. 4 weeks later, partial weight-bearing with a cane can be started.
5, adolescents and young adults (more than 8~10 years old) The morphology of the acetabulum and femoral head of the child has changed greatly, and the soft tissues have also increased their atrophy with the gradual upward movement of the femoral head. It is impossible to pull the femoral head below the level of the acetabulum, and only palliative salvage surgery can be performed, occasionally using bone graft as a frame or vaulting on the iliac wing to cover the femoral head near the acetabulum. Femoral shortening and pelvic osteotomy are rarely considered. After several years, degenerative changes will occur in the hip joint. Causing pain and limited motion, total hip replacement can be performed at an appropriate age. Arthrofusion is rarely done at present. For bilateral dislocations, revision is not always necessary, and total hip arthroplasty is done later.