Diagnosis of Developmental Dysplasia of the Hip in Newborns and Infants

Abstract

It is a review of epidemiology data of development dysplasia of the hip; it was reviewed the pre pathogenic period: agent, host and environment and the role of risk factors for the presence of developmental dysplasia of the hip. What are the clinical data for the diagnosis; the sound transmission tests for the diagnosis of the developmental dysplasia of the hip. Also, the imaging procedures for the diagnosis of the same pathology.

1. Introduction

The developmental dysplasia of the hip (DDH) includes a wide spectrum of abnormalities of the acetabulum and the proximal femur, including dysplasia, subluxation and dislocation of the femoral head [1, 2, 3, 4, 5].

In dysplasia, there is an inadequate development of the acetabulum, the femoral head or both, although there is also a concentric relationship between the 2 articular surfaces. However, in subluxated hips, although there is contact between both articular surfaces, the femoral head is not centered on the acetabular cavity [6]; in the case of dislocation the femoral head is completely out of the acetabulum [7].

Early diagnosis in the first months of life, before the child can walk, is essential, since some children with DDH go unnoticed, despite having used the usual clinical procedures, which only diagnose subluxation or dislocation, and when starting ambulation, the hip joint is injured and cannot be treated with orthopedic measures, and may lead to surgical repair of the joint; In extreme cases, the femoral head becomes necrotic, which requires the placement of a prosthesis.

2. Epidemiology and classification

It is considered that DDH occur 1 per 100 births as instability and 1 per 1000 births as subluxation or dislocation in the United States of America [8]. In Mexico, it is estimated that 1% of neonates have dysplasia and up to 75% of macrosomic neonates have hip alterations demonstrable by ultrasound, but only evolve to dislocation 1 for every 7000 live births [9].

There have been births of children with DDH, anomaly with pathological changes in the size, shape, and cellular organization of the hip that is manifested in the tissue components, soft or hard [10], which for their study are classified in CDD: typical and teratological.

The teratological is an alteration of the embryonic hip, it is called rigid, and the femoral head is outside the acetabulum and its treatment is surgical [11].

The typical or lax DDH is classified as physiological immaturity, subluxation, or dislocation, since it integrates anatomical abnormalities that affect the coxofemoral joint of children, including the abnormal edge of the acetabulum and the malposition of the femoral head causing subluxation or dislocation that affects the development of the hip before and after of birth [12, 13, 14].

This is how, within this spectrum, the defects vary from a slight difference between the articular surfaces of the iliac and femur, to the most severe case when the femoral head is outside the acetabulum; all accompanied by loss of mobility of the affected joint. So, these alterations in the hip cause disability in the infant of great social burden, especially if the child already wanders and the treatment has not been implemented properly [15].

It is important the early diagnosis, mainly before the children walk and ideally before 6 months old; if the children walk, can complicate the treatment of the DDH, and from a conservative treatment (Pavlik Harness or Fredjka Cushion), it should be surgical, with threatening prognosis for hip function.

3. Risk factors

The risk factors can be classified according to the pre- pathogenic period of the natural history of the disease, in agent, host and environment; those of the environment can be classified in microenvironment, Environment maternal and macroenvironment.

3.1 Agent

3.1.1 Maternal hormones

Relaxin is a pregnancy hormone, 6-kDa polypeptide, which increases the secretion of collagenase and activator of plasminogen, involved in collagenolysis [16]. It has been suggested that ligamentous hyperlaxity is a risk factor and that its potential to develop DC is increased due to maternal hormones such as relaxin, which are prepared prenatally to the mother’s ligaments at the time of delivery [17] and cause a decrease in resistance. to the traction [11].

There are two hypotheses in relation to relaxin and DDH:

• The first is a direct effect on the laxity of fetal ligaments, since it influences the metabolism of the connective tissue by estrogen and progesterone. Higher plasma relaxin levels have been reported in dogs with DDH [18] and cord blood from babies with DDH, although the differences were not statistically significant [19].

• Another hypothesis suggests that low concentrations of relaxin are associated with DDH, since in the absence of sufficient laxity of the maternal ligaments, there will be greater pressure on the fetus and may originate DDH [20, 21, 22].

3.2 Host

3.2.1 Heritage

It is considered that there is influence of multifactorial inheritance, combining genetics and environmental conditions; 20% of cases have a family history, 6% if one of the parents was affected, 12% if it was one of the parents and a brother and 37% in monozygotic twins. Up to 20% of these cases have been associated with congenital malformations, such as clubfoot, amniotic bands of the pelvic limbs and congenital muscular torticollis [17]. Ömeroğlu et al., reported in a retrospective study, that there was an association of having a family history of CD with presenting DDH compared with infants who did not have DDH (P = .02, OR = 2.10) [23], although Mendoza et al., in Mexican neonates, found no statistical association between family history of DDHC and DDH in the neonate (P = .73, OR = 0.83) [24].

3.2.2 Position in utero

The breech presentation, especially with the pelvic extremities in extension and adduction, have been indicated as risk factors for DC as well as for hip dislocation since it occurs in 30–50% of cases [10]. Ömeroğlu et al., Reported that breech presentation is associated with DC (P = .015, OR = 1.87) [23]. In the study of Mexican children, a strong statistical association was reported between breech presentation and DC (P =, 004, OR = 5.32] [24].

3.2.3 Firstborn

Being the first child, the uterine force will be greater, being able to exert greater tension to the product [17]. Ömeroğlu et al., studied the relationship with female first-born and DDH; they did not find no association with DDH [23].

3.2.4 Ethnicity

It is considered that the frequency of DC in white race is of 50: 1 compared with African race; it is more frequent among American Indians and Eskimos than in South American or African Indians [11]. Eskimos and American Indians overdress children with legs in extension and adduction or move them in wooden strollers with narrow space; The Huichols in Mexico transport their babies in their body by hanging their limbs in abduction [11]. Highest incidence were reported from Finland, Croatia and Canada (5–195 per 1000), with very low incidences among populations in sub-Saharan Africa and Hong Kong (0–0.1 per 1000) [25]. Geographical and cultural factors regarding climate differences and the practice of swaddling respectively may in part explain this variation [26, 27].

3.2.5 Female sex

It has been reported that the frequency of hip dislocation is more common among women (7:1) in relation to men [11], but DDH is more common in men with up to 1% of live new-borns. Ömeroğlu et al., reported no association between female gender and DDH [23].

3.2.6 High birth weight

In a series of 100 macrosomic neonates in Celaya, Mexico, Figueroa et al., reported that 100% of neonates with clinical maneuvers suggestive of DDH, had ultrasonographic data of DDH and 75% of those with clinical maneuvers negatives, also presented ultrasonographic data of DDH [9].

3.3 Environment

3.3.1 Microenvironment

3.3.1.1 Oligohydramnios

The presence of little amniotic fluid has been indicated as a risk factor for DDH [11, 17], but Ömeroğlu et al., in Turkey, in a retrospective study, found no association between oligohydramnios and DDH in children with DDH compared with children with healthy hips [23]. It is assumed that having little amniotic fluid the contraction force of the uterus will be greater and will affect the product; It is also suggested that by decreasing the amniotic fluid, the product will have more space to place their pelvic extremities in extension and adduction, favoring the instability of the hip.

3.3.1.2 Breech presentation

The breech presentation has been implicated as a risk factor in DDH [4]; products with breech presentation, have twice the risk of DDH [23], the risk is strengthened if it is with the pelvic extremities in extension and intrauterine adduction [10]. Another mechanism is the traction of the pelvic extremities, exerting pressure on the hips for the extraction of a product with breech presentation [11].

3.3.2 Environment maternal

3.3.2.1 Primiparous

The idea that primiparous women have a greater risk of having offspring with DDH due to greater strength of the uterine musculature has been strengthened, which upon contracting will generate greater pressure in the product, but possibly also, due to the fact of a narrower intrauterine cavity [11].

3.3.2.2 Nutrition

Maternal alcoholism has been invoked as a risk factor for DDH [11, 15] and in canine animal models, some dietary factors that favor DDH and the severity of it have been reported [16]. Excessive caloric intake leads to rapid growth and early overload of the bone system and causes an increase in the frequency and severity of DDH in genetically susceptible dogs during the first 6 months of life [16, 28].

It has also been pointed out that elevated serum levels of vitamin C could decrease the frequency of DDH [16], but controlled studies could not demonstrate this [29]. Excessive consumption of vitamin D increases intestinal absorption and renal calcium reabsorption, and this may increase the risk of DDH in canine models [16]. This has led to a tendency to increase the frequency of DDH in the cold months [30, 31, 32] but this does not happen in Finland where the highest frequency was in the months of June and July [33].

Smoking has also been reported as a risk factor for DDH [16].

3.3.3 Macroenvironment

3.3.3.1 Swaddling or excessive clothing

Excessive clothing has been reported as a risk factor in DDH [9, 11]; Mendoza-Lara et al., reported a strong association (P < 0.0004) of swaddling with the pelvic extremities in extension and adduction, with DDH [24]. This has led to a tendency to increase the frequency of DDH in the cold months [30, 31, 32] but this does not happen in Finland where the highest frequency was in the months of June and July [33].

3.3.3.2 Pull on the hip

Obstetric trauma, traction on the hips to extract a product in breech presentation, hold the neonate, after birth, of the heels without support in the back, can cause elongation of the ligaments of the hip and cause DDH [11, 16].

4. Clinical diagnosis

If DDH is in a newborn or children, before to walk, clinical maneuvers as Ortolani, Barlow, Peter-Baden, piston, limitation of abduction can detect, only subluxation or dislocation of the hip. Dysplasia is not detected by these maneuvers.

The sound transmission tests can detect dysplasia, subluxation or dislocation [34, 35, 36, 37].

From the neonatal stage to one year of age, at each visit to the health worker, the following clinical maneuvers should be intentionally sought according to the type of pathology.

4.1 Ortolani’s sign

It is found in subluxable lax hips and is absent in teratological (Figure 1) [17]. Both extremities are taken, one in each hand, placing the knees between the thumb and forefinger, flexing the hips up to 90°, and resting the palm of the hand on the flexed knee and the fingers along the femur, with the Point of the third finger on the greater trochanter, fix the opposite hip by applying slight pressure of the knee towards the table. The hip under examination is pressed vertically and gentle adduction abduction movements are made, looking for the click that occurs when the femoral head jumps over the cartilaginous labrum.

Figure 1.

Ortolani sign.

4.2 Barlow’s sign

It detects subluxation or dislocation hips, the side to be explored is taken with the hand along the femur, with the middle finger located on the greater trochanter and the thumb on the lesser trochanter [17]; hip flexion 90° and abducted 45°; with the other hand the pelvis is fixed. Femur movements are made from front to back. It is considered positive when abnormal play is perceived, and the femoral head moves anteroposteriorly. It occurs in 75% of newborns but disappears after 30 days in 85% of them.

4.3 Galeazzi sign

The patient is placed supine with the hips and knees bent and the feet resting in the plane of the examination table, observing the difference in height of the knees (Figure 2) [17]. The problem side is lowered compared to the opposite side.

Figure 2.

Galeazzi sign.

4.4 Dupuytren’s sign or piston

The patient is placed supine with the leg flexed to 90° at the hip and knee [17]. The pelvis is fixed with the thumb of one hand resting on the anterior superior iliac spine and the index and middle fingers on the trochanter; With the other hand he takes the knee and the leg, making movements up and down (traction and pressure). If it is positive, the displacement of the greater trochanter is perceived.

4.5 Sign of abduction limitation

Patient in supine position, with 90° flexion in hips and knees, gently abducting both legs at the same time [17]. The affected side will show limited abduction. Newborns are abducted at 90°; at 15 days of birth it is 60–70°.

4.6 Peter-Baden sign or fold asymmetry

It is the asymmetry and increase in the number of the inguinal and gluteal folds; in general, the affected side shows higher folds than the opposite limb (Figure 3) [17].

Figure 3.

Peter-Baden sign.

4.7 Comparative sound transmission test with tuning fork and stethoscope

The patient is placed supine with the lower extremities in extension and adduction; a 256-cycle/second tuning fork is placed on one knee and the sound is captured through a stethoscope, placing the diaphragm on the symphysis pubis; the tuning fork is placed on the opposite knee and the sound is compared to the first side (Figure 4a and b) [34, 35, 36, 37]. If the sound is less on either side, it is considered positive for that side. If the DDC is bilateral, the perception of sound will be the same on both sides.

Figure 4.

a. Compared sound transmission. b. Sound transmission with extension/flexion.

4.8 Sound transmission test with extension/flexion

The patient is placed supine and the pelvic limbs are aligned in extension and adduction; the tuning fork is placed on one knee and the stethoscope with its diaphragm is placed on the symphysis pubis; sound is captured; the knee and hip are flexed to 90° and the sound is perceived; it is considered positive if the bending sound increases, if it decreases or stays the same, it is considered negative (Figure 5) [34, 35, 36, 37].

Figure 5.

The above figures are using device in flexion of the hip.

For the extension/flexion sound transmission test, the neonate is placed supine with the lower extremities in extension and adduction; the tuning fork is placed on the knee on one side and the stethoscope is placed on the symphysis pubis and the sound is perceived; the hip and knee are flexed to 90° and the sound is perceived: if the sound is lower or equal, the hip is healthy, if the sound increase, the hip has DDH. The opposite side is subsequently evaluated [34, 35, 36, 37].

Sound transmission test with bone radar ® (University of Guanajuato, Mexico) or electroacoustic probe (Patent pending, University of Guanajuato) [35, 36].

Starting from the properties of bone to transmit sound, we developed a device to apply sound transmission tests in an objective way. The device consists of a sound generator, a receiver placed on a stethoscope and a screen where the sound waves appear transformed into digits [35, 36, 37].

For the comparative sound transmission test, the newborn is placed supine with the pelvic limbs in extension and adduction; the sound generator is placed on the knee on one side and the receiver on the symphysis pubis, the digits are recorded on screens; the sound generator is placed on the opposite knee and the digits are recorded on the screen. If there is a difference in the numbers on either side, it is considered positive. In cases of bilateral CDD, the record will be the same on both sides [34, 35, 36, 37].

For the extension/flexion sound transmission test, the neonate is placed supine with the lower extremities in extension and adduction; the sound generator is placed on the knee on one side and the receiver is placed on the symphysis pubis and the digits are recorded on the screen; the hip and knee are flexed to 90° and the digits are recorded on the screen; If the digits on the screen are greater in flexion than in extension, it is considered positive. The opposite side is subsequently evaluated [34, 35, 36, 37].

For sound transmission test with electroacoustic probe, the technique is the same that bone radar ®, only the digits in screen are decibels.

4.9 Complementary clinical diagnosis

When the child is walking, look for the Trendelenburg and Duchenne signs. Older children who are already wandering, with undiagnosed CDD, present claudication, duck gait (in bilateral cases), increased lumbar lordosis, toe gait, and a discrepancy in the length of the lower extremities.

5. Complications

Recurrent dislocation, avascular necrosis of the femoral head, femoral fracture, and nerve palsy are the most common. The most fearsome complication is avascular necrosis of the femoral head, which is due to the reduction, producing cartilaginous compression and occlusion of extraosseous and intra-articular epiphyseal vessels, causing partial or total necrosis of the femoral head.

6. Diagnostic imaging

Diagnosis in the newborn is clinical and is made through the hereditarily and perinatal antecedents, as well as by the maneuvers of the deliberate exploration. In case of doubt, an echo-sonogram of the hip is used by qualified imaging specialists; It should be noted that radiographs are not useful before 4 months of extrauterine life.

Ultrasonographic diagnosis is made in the newborn and at any other stage of life; It is performed through the static and dynamic test of the hip, with the Graf technique, where the angles α and β are measured in each test. Graph I is considered a normal hip in the child with α >60° and β <55°; Graf II is considered a physiologically immature hip with α 44–59° and β 55–77°; Graph III and IV as a dislocated or dislocated hip with α < 43° and β > 77° (Figure 6a, b) [38, 39].

Figure 6.

a. Graf technique left hip. b. Graf technique right hip.

The radiological diagnosis is based on the findings of the anteroposterior pelvic plates in neutral position and abducted 45° (Lowestein position). The study is useful from the fourth month of age, since the ossification nuclei of the femoral head have already appeared. The following radiographic data can be found: Hilgenrainer’s line is a horizontal one that passes through the triradial cartilages of the iliac; the Perkins or Ombredanne line is a vertical line that passes perpendicularly through the outermost edge of the acetabulum until it surpasses the Hilgenreiner line, forming the Putti quadrants (the femoral head must be in the lower inner quadrant, normally). The angle formed with line that start from the outer edge of the acetabulum and pass through the bottom of the acetabulum until reaching Hilgenreiner line, and Hilgenreiner line, gives us the acetabular index that must be less than 30° (Figure 7a) [11, 17].

Figure 7.

a. AP of the hip. b. Lowenstein. Source: Dr. Jaime González-García.

The Shenton’s arch, passes through the lower edge of the pubis and continues with the lower edge of the femoral neck, forming a normal arch; if there is distortion of this arch, it is considered a dislocated hip (Figure 7a) [11, 17].

Figure 7 a represents the anteroposterior plate of the pelvis in abduction; Look for the Von Rossen sign by drawing a line along the axis of the femur to the midline of the spine (King’s midline); the line usually passes through the acetabulum [11, 17].

Diagnosis at an early stage (under 2 months): in the dislocated hip there is an increase in the acetabular index and absence of the peak of the acetabulum eyebrow. In the dislocated and subluxed hip, lateralization of the proximal internal end of the neck, Von Rossen sign, and alteration of Shenton’s line are located [11, 17].

Late stage diagnosis: in addition to the above, there is Putti’s triad (increased acetabular index, the proximal end of the femur outside and above the Perkins line, as well as delayed ossification of the nucleus of the femoral head) [11, 17].

7. Treatment

Treatment will depend on the age at which the diagnosis is made; the best prognosis is obtained at the beginning of the management in the newborn. In teratological dislocation, the management will always be surgical. In the subluxable hip, wide and thick cushions are used to maintain abduction of the hips bilaterally; they are used for a time in months that is calculated by multiplying the age in months by two when making the diagnosis; monthly clinical control should be performed. Recommending the use of a double diaper should be avoided, because disposable diapers do not maintain hip abduction [11, 17].

In the dislocated and dislocated hip, the abduction of the thighs is achieved, giving stability to the hips, with the use of the Pavlik harness, Fredjka cushion, Von Rossen splint, Barlow splint; These devices remain in place until a stronger joint capsule is obtained, which is achieved in 3 to 6 months.

If the child is already walking and the hip problem has not been detected, the treatment can be surgical and in severe cases, in the event of necrosis of the femoral head, place a prosthesis.

8. Discussion

When receiving a newborn, a checklist for risk factors should be applied, already indicated as suggested by Ömeroğlu et al. [23], and if the infant has one or more, should undergo a Graf ultrasound of the hips to establish whether there is a diagnosis of DDH. The use of clinical tests such as Ortolani, Barlow and others should be postponed until the fourth day of extrauterine life, since there will be false positives due to the processes of Birth, such as passage through the birth canal or potentially the effects of relaxin.

From the fourth day of life, comparative sound transmission tests can be applied, which have shown good sensitivity compared to hip ultrasound [12, 13, 35, 36, 37], unlike the usual clinical maneuvers that show low sensitivity for DDH [13, 35, 37].

Why to use sound transmission tests? Table 1 show validity of the sound transmission test and sound transmission test with extension/flexion.

	Sensibility	Specifity	Positive predictive value	Negative predictive value
Comparative sound transmission
Padilla et al. [12] Padilla et al. [13] Padilla et al. [35] Padilla et al. [37]	72.7; 27.7; 60.9; 44.83; 37.93; 37.93	86.6; 94.35; 92; 97.66; 98.83; 97.66	NR; 87.27; 51.9; 76.47; 84.62; 73.33	NR; 47.7; 95; 91.26; 90.37; 90.27
Comparative sound transmission with extension/flexion
Padilla et al. [12]; Padilla et al. [13]; Padilla et al. [35]; Padilla et al. [37]	74.4; 86.36; 82.6; 82.76; 82.76; 86.21	96.9; 87.09; 96.2; 99.42; 100.0; 100.0	NR; 90.47; 73.1; 96.00; 100.0; 100.0	NR; 81.81; 97.8; 97.14; 97.16; 97.71

Table 1.

Validity of the sound transmission tests.

The compared sound transmission test evaluate both hips, if them have dysplasia, the test give a false negative; this is avoid using the compared sound transmission test with extension/flexion,

It was reported, sensitivity for Ortolani de 5.11%, specificity 96.77%, positive predictive value 69.23%, and negative predictive value 41.81% [13].

For Barlow test, Padilla et al. [13] reported 2.27, 99.19, 80.00, and 41.69%, respectively.

For repeatability, Padilla et al. [35] reported Kappa 0.80 intra-observer and 0.70 inter-observer, for compared sound transmission test and, Kappa.88 and 0.78, intra-observer and inter-observer, respectively, for the sound transmission test with extension/flexion.

With electroacoustic probe, the repeatability was Kappa 0.80 intra-observer and 0.81 inter-observer for compared sound transmission; 0,98 intra. Observer and 0.95 inter-observer, for compared sound transmission with extension/flexion [37].

Since the 80’s of the 20th century, the use of ultrasound of the hips has been recommended instead of radiographs in the newborn and in infants less than 8 weeks of extrauterine life, since with radiography, diagnostic errors are generated due to the lack of ossification of the femoral head mainly.

If the presence of DDH is adequately orthopedically treated, the cure is complete with an excellent prognosis, and this is darkened if it comes to surgical treatment.

In infants, DDH is treated with a Fredjka cushion or Pavlik harness; the double diaper should not be used; if the child is already ambulant, he should be evaluated for surgical treatment of the hip joint. And in this phase, the presence of necrosis of the femoral head should be assessed, since this will lead to the placement of a prosthesis.

The objective of diagnosis and treatment is that the child does not reach the stage of ambulation with DDH and avoid surgical treatment, which is a major procedure.

9. Conclusion

It is a pathology that can go unnoticed and its best prognosis is to detect and treat it before 6 months of age.

The health professional in charge of the care of neonates and infants, should be attentive at each visit, of the state of the hips of each child, applying the usual clinical maneuvers and sound transmission tests, and, if necessary, ultrasound of the hips, and with this, is possible to establish an early diagnostic of DDH.

The objective is to avoid that infants suffer corrective surgery of the hip and/or replacement of the hip.

Acknowledgments

Not funding for this manuscript.

Conflict of interest

Nothing to declare.

Ethics for images

The parents from children give their consent to publish the images because the children cannot be identify.