HIP DISORDERS IN CHILDREN

HIP DISORDERS IN CHILDRENMarietta S, MD., PhysiatristDevelopmental dysplasia of the hip (DDH) is a dislocation of the hip joint that is present at birth. The condition is found in babies or young children.

The cause is unknown. Low levels of amniotic fluid in the womb during pregnancy can increase a baby's risk of DDH. Other risk factors include:The first childFemaleBreech position during pregnancy, in which the baby's bottom is downFamily history of the disorderDDH occurs in about 1 out of 1,000 births.Causes, incidence, and risk factorsThere may be no symptoms. Symptoms that may occur can include:Leg with hip problem may appear to turn out moreReduced movement on the side of the body with the dislocationShorter leg on the side with the hip dislocationUneven skin folds of thigh or buttocksAfter 3 months of age, the affected leg may turn outward or be shorter than the other leg.

SymptomsThe most common method of identifying the condition is a physical exam of the hips, which involves applying pressure while moving the hips. The health care provider listens for any clicks, clunks, or pops.Ultrasound of the hip is used in younger infants to confirm the problem. An x-ray of the hip joint may help diagnose the condition in older infants and children.A hip that is truly dislocated in an infant should be detected at birth, but some cases are mild and symptoms may not develop until after birth, which is why multiple exams are recommended. Some mild cases are silent and cannot be found during a physical exam.Signs and testsWhen the problem is found during the first 6 months of life, a device or harness is used to keep the legs apart and turned outward (frog-leg position). This device will usually hold the hip joint in place while the child grows.This harness works for most infants when it is started before age 6 months, but it is less likely to work for older children.Children who do not improve, or who are diagnosed after 6 months often need surgery. After surgery, a cast will be placed on the child's leg for a period of time.TreatmentExpectations (prognosis)If hip dysplasia is found in the first few months of life, it can almost always be treated successfully with a positioning device (bracing). In a few cases, surgery is needed to put the hip back in joint.Hip dysplasia that is found after early infancy may lead to a worse outcome and may need more complex surgery to fix the problem.ComplicationsBracing devices may cause skin irritation. Differences in the lengths of the legs may persist despite appropriate treatment.Untreated, hip dysplasia will lead to arthritis and deterioration of the hip, which can be severely debilitating.

Developmental dysplasia andcongenital dislocation of the hipDefinition Developmental dysplasia of the hip (DDH): Inadequate development of the hip with impaired ossification of the lateral acetabular epiphysis Congenital dislocation of the hip (CDH): Displacement of the femoral head from its central position in the acetabulumThe dysplasia rate in Central Europe (Germany, Czech Republic, Austria, Switzerland, Northern Italy) used to be from 24% until the late seventies. Today it is much lower. The dislocation rate (in historical studies) was 0.51%.In the UK, the USA and Scandinavia, the dysplasia rate is 0.51%, and the dislocation rate less than 0.05%.In a recent study in the UK, 88 dislocations were found in 34723 neonates (=0,25%)The absence of hip dysplasia among the primitive tribes of Africa to the fact that the infants are carried by the mother at the side, resting on the pelvis, or on the back with spread legs.Other more northerly located primitive peoples, North American Indian tribes tend to wrap their infants tightly and accordingly experience high dislocation rates.

Diagnosis

Clinical diagnosis in the neonate History Family history (hip dysplasia or premature osteoarthritis of the hip) Firstborn child Amniotic fluid deficiency Breech presentation .ETIOLOGYSince the introduction of the ultrasound screening method by Graf, we know that, in addition to dysplastic and dislocated hips, there are a large number of immature hips.Percentages as high as 30% have been reported.As part of the evolutionary development of humans, the upright gait led to a widening of the iliac wing to provide additional support for the abdominal organs

To this immaturity can be added a number of other factors: genetic, hormonal and mechanical.Dunn [22] differentiated two types of hip dysplasia. Thegeneral joint hypermobilitydysplasia ofthe acetabulum , without any significant ligament laxity

The first group shows general joint hypermobility , which manifests itself at birth as hip instability. Girls are predominantly affected (the ratio of boys to girls in this group is 1:12) Hormonal, genetic and constitutional factors play a major role in this group

The second group is characterized by dysplasia of the acetabulum , without any significant ligament laxity.increasingly observed particularly in oligohydramnios. This acetabular immaturity, breech presentationconnection with other deformities or malformations, e.g. clubfoot, flat feet, facial asymmetries and muscular torticollis. ratio of boys to girls 1:2, and the left side is twice as likely to be affected as the right side.Mechanical factors associated with the lack of space for the neonate in the uterus play a major role in this group. The consequence is delayed ossification of the lateral acetabular epiphysis, i.e. dysplasia, which leads to secondary dislocation as a result of the inadequate contouring of the acetabular roofHowever, the dislocation itself very rarely occurs at birth, but tends to occur secondarily during the course of the first few months of life as a result of the increasingextension in the hip.dysplasia of the acetabulum , without any significant ligament laxityAs the displacement progresses, the femoral head comes out of the acetabulum, usually in a craniodorsal direction.The acetabulum is secondarily filled with fatty and connective tissue. If the femoral head has left the acetabulum, shortening of the iliopsoas muscle will occur.The tendon, which is located right next to and partially fused with, the hip capsule, strangles the capsule and becomes an obstacle to reduction.The elevated position of the femoral head causes shortening of the legthe abductors (particularly the gluteus medius and minimus muscles) & hip extensors (gluteus maximus) are shortened and weakened. to a flexion contracture of the hip and, on the other, to the inability to stabilize the pelvis when standing on one leg. The consequence is an abnormal pelvic tilt that is compensated by hyperlordosis of the lumbar spine

Testing for shorteningof the thigh (a) in hip dislocation and forabduction (b)

Clinical examination

InspectionAsymmetry of skin folds : Pronounced asymmetry of theskin folds can be an indication of unilateral dislocation.skin folds in the infant are almost never completely symmetrical, this examination is not very informativeLeg length examination : With the hip and knee flexed atright angles, the thigh on the dislocated side is noticeably shorterORTOLANI TESTThe hip and knee are flexed at 90. Grasp the knee, placing the thumb on the inside of the thigh and the index and middle fingers around the greater trochanterFirst hold the legs in an adducted position and apply gentle pressure in the dorsal direction. Then perform an abduction maneuver, applying slightly greater pressure to the greater trochanter

Ortolani.If the femoral head had been subluxated in the adduction position, a click is perceived as it snaps back into the acetabulum.

Barlow TestBarlows test is similar to that of Ortolani, but places less emphasis on the abduction/adduction maneuver, and more on the thumb pressure. Place the hips in a position of central abduction. First apply pressure to the greater trochanter to test the reduction maneuverThen, from the same abduction position, try to dislocate the femoral head by applying pressure dorsally and laterally

If it snaps back into place, the hip is dislocatable. Stabilize the pelvis with the other hand by placing the thumb on the feet and encircling the sacrum with the other fingers. The Ortolani click and the Barlow sign remain positive for approx. 4 weeks in an unstable hip,

Barlowortolani

Ludloffs dislocation sign : Extension of the knees is not normally possible if the hip is flexed by more than 90 because of the tensing of the hamstrings. If the hip is dislocated however, the knee can be extended in this position

ROMNeonates usually show a flexion contracture of around 3040. This is a physiological finding, since both hips are flexed more than 90 within the uterus.Since it is not possible therefore to examine rotation in the extended position, rotation is examined in the flexed position in the usual way

Since the femoral head center starts to ossify after a year or so, the diagnosis must then be made radiologically. At this age, only the AP view is normally recorded The AP view in the infant should always be an x-ray of both hips so that the pelvic position and the horizontal situation can be evaluated

Line.The Hilgenreiner line joins the two Y-lines of the triradiate cartilage and thus forms the horizontal on the pelvic view.The Ombrdanne line is drawn from the lateral edge of the acetabular roof, i.e. the lateral acetabular epiphysis (perpendicular to the Hilgenreiner line) and crosses through the Hilgenreiner line to form four quadrants. Normally the center of the femoral head is in the lower inner quadrant

Orientation line according to Shenton and Mnard :Normally the continuation of the medial femoral neck contour forms a smooth arc as it passes through the superior border of the obturator foramen. In a dislocated hip this arc is disrupted because the femoral neck is displaced upwards.Acetabular roof angle = AC angle or acetabular index angle between the horizontal (Hilgenreiner line) and the line joining the Triadiate cartilage and the lateral acetabular epiphysis. The average angle at birth is 30, at 1 year slightly over 20 and at 3 years of age under 20.

Mean value ACE

Hip arthrographyHip arthrography is suitable for evaluating the cartilaginous sections of the hip, the ligament of head of femur and other soft tissues.From the gluteal fold, a long needle is inserted under sterile conditions and advanced up to the hip under image-intensifier control. 23 ml of contrast medium (Jopamiro) are injected

ULTRASOUNDAt the start of the 1980s, Graf developed a sonographic screening technique for the infant hip that represented a significant advance in the diagnosis of congenital dysplasia of the hip.Sonography of the hip is performed from a lateral approach, and the ilium as displayed on the image must be parallel with the ultrasound head.

Suitable frequencies are the 7.5 MHz transducer head for small infants and the 5 MHz head for larger infants.Graf introduced two angles as a guide to evaluation: alpha angle and beta angleGRAFT methodAlfa angle (angle between the lateral acetabular epiphysis and triadiate cartilage and the lateral margin of the ilium) beta angle (angle between the lateral border of the ilium and a line joining the lateral acetabular epiphysis and labrum).

Graf subsequently proposed a classification taking into account the various conditions of the hip :the centering of the femoral headmaturation of the bony epiphysissteepness of the acetabulum and the age of the patient

Ultrasound

Ultrasound

If general screening is not available, the ultrasound examination should at least be indicated if certain broadly interpreted risk factors are present.The corresponding risk factors are: a family history of hip dysplasia or coxarthrosis, premature birth , breech presentation, other skeletal anomalies, oligohydramnios , clinical suspicion of hip dysplasia.Screening with USRehabilitation time line in DDH (Teclin)

Conservative treatment

The following types of treatment are differentiated: maturation treatment, closed reduction, immobilization.

MATURATION TREATMENTIf an immature hip of type IIa or IIc is detected on the ultrasound scan, the femoral head is not dislocated and does not therefore need to be reducedA maturation treatment with abduction pants or a Tuebingen splint

The abduction pants were introduced by Frejka in 1941 These are made of a plastic material and incorporate a rigid bar placed between the legs.The pants hold the legs in abduction and are worn over the infants normal clothes. The orthosis cannot be worn continuously since it must be removed for nursing care purposes or when changing the babys clothes.

High rates of avascular necrosis were reported during the first few years of abduction splinting [83], at a time when these orthoses were used for reductions.Excessive abductions of up to 90 were also employed.We therefore use the Tuebingen splint developed by A. Bernau for maturation treatmentThis produces less pronounced abduction but greater flexion than standard abduction pants. It is easy to handle and its size can be adjusted to fit the infant. Since it is made from plastic, hygiene is less of a problem than with the Pavlik harness, for example, which is made of fabric

Reduction methods

We differentiate between the following options: manual reduction methods, braces for reduction, traction methods.Manual reduction methodsManual reduction methods are of historical significance only as the associated complication rates were far too high. Manual reductions were described by Lorenz 1895 and Lange in 1898Reduction bracesThe Pavlik harness incorporates two shoulder straps that cross over at the back and are fastened to a broad chest strap which fastens at the frontThe lower legs are enclosed by stirrup-like straps, with the topmost strap encircling the leg just below the knee.The distance between the chest strap and the lower legs can be adjusted separately by means of buckles at the front and back

The legs are first placed in a flexion position of approx. 110, which should then be gradually supplemented by increasing abductionAn additional transverse strap can prevent the distraction from exceeding 60.This repositioning of the dislocated hip can take a few days in some children, but may require several weeks in others.The dislocated hips reduce themselves spontaneously as a result of the babys thrashing about, and no actual reduction maneuver is neededThe use of this harness beyond the age of 9 months is not recommended .In the hands of skilled practitioners, reduction with the Pavlik harness is a reliable method with few complications report a high number of unsuccessful reductions and complicationsOn the one hand, these findings were very probably the result of inadequate compliance on the part of the mothers. The Pavlik harness is relatively complicated & the numerous straps can be confusing for the parents.For hygienic reasons, the harness has to be changed frequently, and the constant readjustments can be problematic.The main problem : harness very easily becomes soiled by the child & cannot then simply be wiped down like a plastic splint.one study that plastic splints are much easier to managethe Pavlik harness is more suitable for reducing subluxated (Graf type III) hips than completely dislocated (Graf type IV) hips Another study a relatively high necrosis rate of 33% after reduction with the Pavlik harness

Traction methods

There are two methods: longitudinal traction overhead traction

LONGITUDINAL TRACTIONLongitudinal traction for reducing the hip is the first known therapeutic procedure and was described by Pravaz in 1847It is still used today, in some cases as a home-based treatmentThe traction is achieved with plaster strapping affixed to the legs. Aboard placed beneath the feet is designed to avoid pressure on the malleoli. The traction weight is initially 1/7 of the infants weight, but can subsequently be increased to 1/4 or more.The skin should be monitored carefully.Triangular pants can be used to provide counterforce, or else the foot of the bed can be elevated so that the weight of the body is shifted towards the head.The legs are abducted by approx. 20OVERHEAD TRACTIONOverhead traction was introduced in1955 by Craig & remains a widely used method even today.This traction can also be employed for older children for whom a Pavlik harness is no longer appropriate.Overhead traction requires the fitting of two bars at the side of the bed which are linked together above the bed by a crossbar. Overhead tractionA weight of 11.5 kg is attached to the childs legs with strapping and exerts traction via a cord that runs over pulleysThe degree of traction should initially be adjusted to produce a flexion of over 90. The pulleys are then shifted laterally to gradually increase abduction

Overhead tractionWe shift the pulleys so as to achieve an abduction of around 70 after 8l0 days. By this time spontaneousreduction has occurred in most cases, and this can be checked by arthrography. If the traction were increasedto 90 abduction, there would be an increased risk of femoral head necrosis. Reduction with overhead traction must be followed by immobilization, for which we use the Fettweis spica castTraction improves the chances of a successful closed reduction and reduces the risk of avascular necrosis of the femoral head

immobilizationThe following can be used for immobilization: plaster casts, splints, braces, abduction pants

Plaster castsHip spica in the Lorenz positionThis oldest known immobilization treatment described by Lorenz in 1895

fixed the hips in an abduction position of 90 (also known as the frog position)very many cases of avascular necrosis of the femoral head have occurred as a complication of immobilization in this position the intraarticular pressure produced by pronounced abduction and internal rotation is excessive and causes constrictionof the intra-epiphyseal vessels in the soft cartilageImmobilization in a squatting position according toFettweis In 1968 Fettweis proposed a treatment of reduction and immobilization in a hip spica in the squatting position, in which the hips are flexed by up to 110120, but limiting the abduction to approx. 50 60the rate of avascular necrosis is much lower, at around 5%The long-term treatment with the Fettweis cast is also very well tolerated by the children

After a reduction use the Fettweis cast for at least 8 weeks for immobilization purposesThe cast must be changed after 4 weeks. The cast can be changed under light sedation and does not usually require general anesthesia. The feet do not need to be included in the cast but can be allowed to move freely.

Various abduction splints are used for immobilization purposes. These are particularly suitable as follow-up treatment after immobilization in a Fettweis hip spica.The Denis Browne splint, introduced in 1948 used to be very popular since it was very easy to manage.However, since it suffers from the drawback of having been designed for an abduction position of 90 this splint should no longer be used.Numerous modifications of the Denis Browne splint , with the aim of producing a better position, have been proposed.A well-known example is the Tuebingen splint which we tend to use. After a congenital dislocation of the hip, we follow 3 months of permanent immobilization in the squatting cast with a further 3 months of splint treatment.

Tuebingen splint

Pelvic harnessThe Pavlik harness is also suitable for immobilization purposes, although it is not particularly appropriate for use in infants older than 9 months.Since the Pavlik harness is not very practical for the mother, we only use it occasionally. Various reports inthe literature have described failed reduction or subsequent dislocation in the caudal direction after the use of the Pavlik harness The treatment is only suitable if the parents are cooperative and intelligent.

complicationAvascular necrosis of the Femoral headThe commonest and most serious complication of treatment of congenital dislocation of the hipIn most cases, the necrosis is a consequence of treatment and does not result from the dislocation itself. The necrosis can occur in the epiphyseal plate either laterally, centrally or medially

Avascular necrosisResults shortening of the femoral neck, or head in neck position, and overgrowth of the greater trochanter. The same shortening of the femoral neck and overgrowth of the greater trochanter is also seen with central necrosisMedial necrosis results in a coxa vara. But the necrosis can also affect the acetabulum.

Follow up (min x ray)