DDH is the most common abnormality in the neonate, with an estimated incidence ranging from 1% to 3% with clinical examination and from 4% to 5% with ultrasonic examination.10–12 Approximately 1 of 20 full-term babies are born with some hip instability, and 2 to 3 of 1000 infants require treatment.13 Risk factors associated with DDH in otherwise healthy infants include breech presentation, higher birth weight, older maternal age, race, female sex, family history, oligohydramnios (low amniotic fluid), and clicking hips during examination.2,8,14 Postural deformities, such as torticollis and lower extremity deformities, are also associated with DDH.7 Additionally, improper swaddling with the hips and knees in extension and limited abduction, as practiced in some cultures (e.g., Japanese, Native American, Turkish, and Australian cultures), has been implicated in an increased incidence of DDH (Fig. 7-2).2,7
Female sex, positive family history, race, and intrauterine position are the most critical risk factors.8 Higher rates of DDH occur in female patients because they are especially susceptible to the maternal hormones relaxin and estrogen, which may contribute to ligamentous hyperlaxity resulting in instability of the hip in the neonate.2,15 If a parent has a history of DDH, the infant is 12 times more likely to develop DDH, and the risk increases to 36% if a parent and sibling have DDH.16 The incidence of DDH is decreased among black or African American individuals in comparison with all other races.8 Limited movement related to intrauterine position and breech position at birth are strongly associated with DDH.8
Early diagnosis and treatment of DDH through hip abduction positioning devices can improve long-term outcomes (see Figs. 7-17 to 7-21).2 Screening for DDH begins immediately following birth with identification of risk factors and physical examination of the newborn. Physical examination includes clinical provocative tests, described in detail later in this section. Screening may also include static and dynamic ultrasound examination to detect skeletal abnormalities and instability of the hip joint. Diagnostic ultrasonography is often used to confirm the presence of DDH (Fig. 7-3). It can distinguish cartilaginous components of the acetabulum and the femoral head from other soft tissue structures, it permits multiplanar examinations to determine the position of the femoral head with respect to the acetabulum, it does not require sedation or ionizing, and it is less expensive than computed tomography (CT) or magnetic resonance imaging (MRI).7
The evidence to date, however, does not indicate with certainty that screening for DDH is effective.17 Universal ultrasonic screening, in particular, is highly debated among experts. Ultrasonic examination has been implemented universally for all infants, or selectively for those infants who present with risk factors, but little evidence supports ultrasonic examination as being more efficacious than clinical examination alone. Skeptics argue that a higher potential exists for overtreatment of hips that will resolve untreated, or treatment of otherwise normal hips as a result of false-positive findings,2,7 and that abduction treatment can potentially cause avascular necrosis of the femoral head. “The role of ultrasonography is controversial, but it generally is used to confirm diagnosis and assess hip development once treatment is initiated.”8
A randomized controlled trial (RCT) by Laborie and associates18 compared selective ultrasound screening, universal ultrasound screening, and clinical screening alone for DDH. This study was a maturity review of an initial RCT. The initial RCT included 11,925 infants born within a -year span between 1988 and 1990. In the initial trial, the infants were randomly assigned to 3 groups: universal ultrasound screening, selective ultrasound screening, or clinical screening alone. The maturity review was conducted between 2007 and 2009, and 2038 infants from the original RCT, born in 1989, were ultimately included in the review. Although more infants were identified and treated in the universal ultrasound screening group, and the least number of infants was identified and treated in the clinical examination only group, findings indicated no significant difference between groups for rates of hip reduction in radiographs at skeletal maturity, concluding that universal ultrasound screening and subsequent treatment had no significant impact on radiographic signs of dysplasia or early degenerative changes at skeletal maturity. Additionally, findings indicated a nonsignificant difference in the rate of late-presenting cases; thus ultrasonic examination did not appear to “catch” cases potentially missed during screening through clinical examination alone.18 Nevertheless, some health systems have implemented universal ultrasound screening in an effort to reduce the rate of late diagnosis.17 Of note is the finding that increased treatment rates in the universal ultrasound screening group were not associated with a higher incidence of avascular necrosis of the femoral head, thereby indicating no adverse effects to abduction treatment in the study subjects.18
Evidence supports routine clinical examination by a clinician trained and skilled in performing tests to detect hip instability in all infants.2 Despite limited research to support the value of ultrasonic examination, some experts advocate its use through risk stratification to inform selective use for female infants born in breech position.17 Neonatal screening using a combination of clinical examination and selected ultrasonic examination is recommended by the American Academy of Pediatrics (AAP).15 Refer to Table 7-1 for a summary of recommendations outlined in the AAP clinical practice guidelines for early detection of DDH.
American Academy of Pediatrics Guidelines for Early Detection of Developmental Dysplasia of the Hip in Newborns
|Risk Factor Stratification||Recommendation|
|All infants||Physical examination by a properly trained health care provider (e.g., physician, pediatric nurse practitioner, physician assistant, or physical therapist)|
|Positive Ortolani or Barlow sign||Referral to orthopedist|
|Female and breech delivery||Hip imaging:|
ultrasound at 6 wk of age
radiographs at 4 mo of age
|Male infants born in the breech position||Hip imaging optional|
|Female infants with a positive family history of DDH||Hip imaging optional|
As stated previously, physical examination should take place immediately after birth, and it should begin with a general examination to detect conditions associated with DDH such as torticollis or other postural deformities.7 Both lower extremities should be observed in the supine position, without a diaper, for the presence of femoral shortening (referred to as the Galeazzi sign), and for skinfold asymmetry (Figs. 7-4 and 7-5). Although asymmetric skinfolds are not specific to DDH, they are a common finding in unilateral hip dislocation, as is leg length discrepancy (LLD).8 The Galeazzi sign, unequal height of the knees, is elicited by placing the child supine with both hips and knees flexed, and it is typically caused by hip dislocation or congenital femoral shortening. A higher incidence of DDH of the left hip (60%) than the right hip (20%), or of both hips (20%), is reported.8
Hip abduction should also be evaluated because limited hip abduction develops by 3 months of age on the affected side in infants with hip dislocation.8 Hip abduction of less than 60 degrees on the affected hip may indicate hip dislocation. If DDH is bilateral, the infant will present with limited abduction in both hips. Limited abduction is particularly important in identifying bilateral hip dislocations because the leg lengths may appear equal, with a negative Galeazzi sign, and no apparent asymmetries8,9 (Fig. 7-6).
• Each test is performed one hip at a time, with gentle force (Fig. 7-7)
High-pitched clicks are commonly elicited with flexion and extension and are inconsequential. A dislocatable hip has a rather distinctive clunk, whereas a subluxable hip is characterized by a feeling of looseness, a sliding movement, but without the true Ortolani and Barlow clunks. Separating true dislocations (clunks) from a feeling of instability and from benign adventitial sounds (clicks) takes practice and expertise.15
In many cases, physical and sonographic screenings result in false-positive findings, and signs of instability disappear within a few weeks. For this reason, unless examination reveals actual dislocation, the infant can be observed for 3 to 6 weeks before treatment is initiated.7 If evidence of DDH is noted through physical and ultrasonic evaluation following the 3- to 6-week observation period, treatment is indicated.7
Despite neonatal screening protocols and diagnostic imaging, DDH may go undiagnosed until the child is 18 months of age or older.15 In children who are older than 3 months of age, the Ortolani and Barlow tests become difficult to perform because of soft tissue contracture. At this time, physical assessment focuses on secondary signs of hip dislocation: restricted abduction, LLD, and, once the child is walking, a Trendelenburg limp.8 These signs may not appear until the child is older than 9 months of age, and limping in response to a weak gluteus medius muscle may be the first sign of a dislocated hip8 (Fig. 7-8).
The period between birth and the first few weeks of life may be the best time for prevention of DDH.2 Parent education on proper swaddling and improper use of carrying or positioning devices may be beneficial in preventing DDH. Some swaddling practices and devices may position the infant in restricted hip abduction, with the hips and knees in extension. Proper swaddling, positioning, and carrying with the hips in abduction, with the hips and knees in flexion, may lessen the risk of DDH. Refer to Figure 7-9 for examples of improper and proper swaddling, carrying, and positioning. The triple-diaper technique, which increases abduction position of the hip in newborns, has also been used to prevent DDH, with little evidence of its success.20
The goal in the management of DDH is to achieve a stable, concentric reduction of the hip to ensure that any dysplasia is adequately corrected and to avoid the complications of treatment, the most significant of which is avascular necrosis (AVN) of the femoral head.6
Early treatment during infancy typically consists of an abduction positioning device, the most common of which is the Pavlik harness (Fig. 7-10), introduced by Arnold Pavlik in 1946. Other abduction treatments include the von Rosen splint, the Craig splint, the Ilfeld splint, hip spica casts, and the Frejka abduction pillow, although the Pavlik harness is the most commonly used and recommended device7,21 (Figs. 7-11 to 7-15).
The Pavlik harness is a dynamic positioning device to allow free movement within limitations imposed by lower extremity straps that restrict extension and adduction of the hips. The harness is used full time until evidence of reduction is shown using ultrasonography or other imaging. Successful reduction, or maintenance of a reduced but dysplastic hip, has been reported at rates of 80.2% to 100% using the Pavlik harness, with higher success rates if treatment is initiated when the child is younger than 7 weeks of age.6,19 Little consensus exists regarding timing of Pavlik harness use, with concerns of overtreatment if it is initiated too early (before 6 weeks) and an increased risk of failure if it is initiated when the child is older than 4 months of age.6 The Pavlik harness, however, is the international gold standard for children younger than 6 months of age.19 Evidence regarding duration of harness treatment is also limited, varying from 11 to 28 weeks.6 Nevertheless, most experts recommend surveillance during treatment with ultrasonography to determine duration based on success of treatment.6–8
If a dislocated hip is not reduced with harness treatment within 3 weeks, the harness should be discontinued, and an alternative treatment should be considered. In these cases, alternative treatment generally consists of closed reduction, with the patient under anesthesia, with spica casting (see Fig. 7-14); this is also the treatment of choice for children who are older than 6 months of age.8
Adverse effects of the Pavlik harness are uncommon and have been attributed to compliance issues from parental misunderstanding or physician misuse or issues related to the severity of the DDH.7,22 Adverse effects include transient femoral neuropathy caused by persistent hyperflexion of the hips and avascular necrosis caused by excessive abduction; avascular necrosis is rare, with a reported incidence of less than 1%.7,8 Another problem related to misuse of the harness occurs when a hip is not adequately reduced and rests on the posterior lip of the acetabulum for a prolonged period, thus causing blunting of the acetabulum and a form of dysplasia (termed Pavlik harness disease).7 Close follow-up, early recognition and management of adverse effects, and parental involvement and education can minimize complications and improve success of treatment (Fig. 7-16).
In the event that closed reduction treatment is not successful, open reduction should be considered. Open reduction of the hip in a child with DDH involves lengthening tendons, removing obstacles to reduction, and tightening the hip capsule once reduction is obtained.8 Complications include femoral head necrosis and repeat dislocation. In older children, open reduction becomes more complex, and by 18 months of age, femoral osteotomies with or without pelvic osteotomies may be necessary.8
Childhood and Adolescence
Patients diagnosed with DDH are routinely monitored for residual dysplasia into adolescence. In some cases, children who are treated in infancy for DDH may present with dysplasia after skeletal maturity, and others may not show signs and symptoms of DDH until adolescence.12,23 Evidence indicates that adolescent DDH and infantile DDH are two distinct conditions with different etiologic factors: in a study of 541 patients with acetabular dysplasia, demographic differences were found between patients with infantile DDH and adolescent-onset of DDH.23 The infancy-diagnosed group had higher rates of environmental factors associated with dysplasia (i.e., left-side hip involvement, breech presentation, and first-born birth). The adolescent-diagnosed and adult-diagnosed group (9 to 51 years old) had a higher male incidence, increased bilateral hip involvement, and a first-order family history of total hip arthroplasty before age 65 years, thus indicating a separate disease process. According to the findings, adolescent-diagnosed dysplasia is not detected until symptoms develop; this feature suggests the need for screening younger family members of patients with osteoarthritis to identify those at risk.23
The most common symptom of DDH in adolescents is an insidious onset of hip pain. Thorough review of the child’s medical and family history can identify factors associated with DDH and can rule out other causes of hip instability.9 Differential diagnosis can be accomplished through provocative tests including the impingement test for acetabular lesions, the apprehension test for instability, and the bicycle test for abductor insufficiency.1,15 Positive test findings indicate the need for confirmation through imaging.
MRI is preferable to radiographs or CT in children and adolescents to evaluate acetabular morphologic features before closure of the triradiate cartilage, which occurs at 12 years in girls and at 14 years in boys. The posterior wall of the acetabulum develops late in a predictable fashion. If the posterior wall is not fully developed, a higher rate of false-positive results may result from the radiographic appearance of acetabular retroversion and a hypoplastic posterior wall.24
Untreated hip dysplasia may cause early degenerative hip arthritis. Intervention for moderate or severe hip dysplasia in adolescents or young adults is generally surgical, to restore joint stability and mechanics and delay the onset of osteoarthritis.1 Several surgical approaches to adolescent typical developmental dysplasia are used, including acetabular osteotomy,25 Ganz osteotomy,26 and Bernese periacetabular osteotomy.3 Symptomatic patients with closed triradiate cartilage and no or minimal arthritis benefit from periacetabular osteotomy. Bernese periacetabular osteotomy is recommended and has good results in these patients.3 For patients who already have severe arthritis and cartilage damage, more conservative treatment including nonsteroidal antiinflammatory medication and physical therapy is recommended until total hip replacement is necessary.1
Rehabilitation Considerations and Programming
Rehabilitation after surgical intervention depends on the procedure performed. Immediately following Bernese periacetabular osteotomy, the patient is typically on bed rest, with the knee and hip flexed, and can begin touch-down weight-bearing with crutches by day 2.3 Patients usually increase weight bearing at approximately 6 to 8 weeks and are off crutches after 3 or 4 months postoperatively.3,26
In cases of total hip arthroplasty, home physical therapy is effective in improving hip muscle strength and function when the therapy is practiced at least three times per week, although compliance with the exercises may be an issue for the adolescent patient that can delay return of preoperative strength.26 Immediate postoperative full weight bearing and intense physical therapy appear to reduce the time to return to preoperative strength.26 Some evidence indicates that the addition of hippotherapy to a traditional physical therapy program may improve motor functioning in a child with DDH.27
Teratogenic and Neuromuscular Hip Dysplasia
Teratologic hip dysplasia refers to the more severe, fixed dislocation that occurs prenatally, usually in children with genetic or neuromuscular disorders.8,15 Diagnosis and management of teratologic and neuromuscular hip dysplasia differ from those of typical DDH.
Children with neuromuscular disorders may develop dysplasia because of muscular imbalances and abnormal muscle tone that cause the joint to become unstable. Children with spasticity often have movement patterns of adduction and internal rotation, and they present with lower extremity scissoring and internal rotation during functional positions, mobility, and, in those who are ambulatory, walking. These persistent posturing and movement patterns may cause the femoral head to translate over the posterior edge of the acetabulum. This posterolateral, and even global, acetabular deficiency seen in neuromuscular or teratologic DDH is in contrast to the anterosuperior acetabular deficiency seen in typical DDH.28 Pelvic osteotomies that address the acetabular deficiency and optimize coverage of the femoral head may become necessary to improve hip stability in these patients. Conservative management, including physical therapy, may delay or prevent the need for surgical treatment in patients with teratologic and neuromuscular dysplasia.
Physical therapy assessment and treatments to address and maintain proper hip position can prevent the development of hip dysplasia and can manage existing dysplasia in children with teratologic and neuromuscular conditions. The identification of flexibility and strength imbalances is important to allow the child to obtain and maintain neutral positions of the hip and lumbopelvis. Adequate hip range of motion (ROM) must be achieved through a stretching program, and it should be supported through use of positioning and orthotic devices and an appropriate seating support system that encourages a neutral hip position (Figs. 7-17 to 7-21). Additionally, the therapist should address postural control and balance responses to maintain alignment during functional movements. For ambulatory children, alignment during weight bearing and gait is particularly important. In fact, walking has been shown to be beneficial in hip development in children with cerebral palsy.29 These strategies can keep an unstable hip from becoming fully dislocated, or they can prevent secondary hip problems from developing in children with abnormal muscle tone and can improve the quality of life for children and their families.30,31
Congenital Femoral Deficiency
CFD is a rare birth defect that was formerly known as proximal femoral focal deficiency (PFFD), and it encompasses a spectrum of severity of femoral deficiency, deformity, and discrepancy. Patients with CFD have a degree of lack of integrity and stability of the hip and knee (deficiency), malorientation and malrotation of the femur with soft tissue contractures (deformity), and femoral shortening (discrepancy). The incidence ranges from 1 in 40,000 live births to 1 in 100,000 live births for those cases associated with fibular hemimelia,32 and it can manifest unilaterally or in both femora.
Etiology and Classification
The etiology of CFD is not entirely known, but it does not seem to be associated with hereditary factors. Some toxins such as thalidomide exposure in early pregnancy are known to cause the disorder.33 Other theories that have been proposed include sclerotome subtraction postulating an injury to the neural crest, and more recently it has been hypothesized that a defect in the maturation of chondrocytes at the growth plate may be responsible for the development of CFD.
Two major classifications of CFD are used. The Paley classification addresses radiologic and soft tissue presentations of the condition and is based on factors that will influence reconstruction and limb lengthening (Fig. 7-22).32 The Aiken classification is descriptive, based solely on radiologic factors,34 and it is primarily focused on factors associated with amputation or prosthetic reconstruction of the limb.32 The treatment discussed in this chapter uses the Paley classification system and its recommendations.
Patients with most forms of CFD do very well with reconstruction and limb lengthening. A surgical reconstruction life plan is important for planning and should be given by the surgeon at the first visit. In very severe forms, Paley type 3, pelvic support osteotomy and foot amputation may be recommended when the family finds a rotationplasty to be an unacceptable option or when the foot is severely dysplastic.35 Otherwise, with Paley type 3 CFD, in which the foot and ankle are stable, a rotationplasty is recommended to use the strength of the gastrocnemius muscles to extend the prosthetic limb forward (Fig. 7-23). LLD can be predicted,36 using the Paley growth application software for smartphones.
If reconstruction and lengthening are recommended, an initial preparatory surgical procedure will be performed to stabilize the hip and the knee. To lengthen any segment safely, the proximal and distal joints must be stable.37 The stabilization operations vary with the Paley classification type, and full explanation is beyond the scope of this chapter, but the surgical procedure can take place as early as 18 to 24 months of age. The surgical procedure to stabilize the hip is referred to as a systematic utilitarian procedure for extremity reconstruction (SUPER) hip one or SUPER hip two; similarly, the knee stabilization operation is referred to as a SUPER knee. Both can be accomplished at the same time, although not all children will need both.38 Lengthening of the femur can begin as early as 3 years of age, once the child has fully recovered from the stabilization procedure (Fig. 7-24).
The initial lengthening requires an external fixator that will span at least the length of the femur and cross the knee to the tibia to prevent posterior subluxation of the tibia during the lengthening process (see Case Study 7-2, at the end of the chapter). Multiple pins are inserted into the femur through the skin above and below the site of the osteotomy to stabilize and distract the bone. This works as an external scaffolding and allows for weight bearing as tolerated in patients with normal sensation. A hinge at the knee allows for ROM and stretches to be performed. Some patients with a hip joint that requires further stabilization during lengthening have external fixation that extends to the pelvis, and they may or may not have a hinge to allow hip motion. Botulinum toxin is often injected into the quadriceps muscle to minimize spasms and facilitate knee ROM throughout the lengthening process.
The lengthening process has three phases: (1) latency, (2) distraction, and (3) consolidation. Latency phase is the time between the osteotomy procedure and the beginning of the distraction, and it results in the initial callus formation of the bone. The latency period lasts 1 to 7 days. Distraction is the phase where the bone is slowly pulled apart (0.25 mm, four times per day, for a total rate of 1 mm per day), thereby stretching the bone callus that will form the bone regenerate. The distraction phase continues until the goal is met or the lengthening is stopped because of complications. The rate of distraction can be slowed to address decreasing passive ROM. Typically, 8 cm is the maximum length that can be achieved safely with each femoral lengthening. Consolidation is the phase when the distraction stops and the regenerate fills in, thus allowing the bone to heal and strengthen to support the full weight of the body.37 This phase is typically as long as the distraction phase in children, and it is 1.5 times the distraction phase in adults.
For subsequent lengthening procedures, the child may be a candidate for an internal device if the length and shape of the femur are adequate for insertion of the telescoping rod (see Case Study 7-2, for PRECICE [Ellipse Technologies, Inc., Aliso Viejo, Calif.] lengthening nail images). Lengthening procedures are recommended at 4- to 6-year intervals, depending on the total length that the child requires if external fixation is used. When using implantable devices for lengthening, shorter lengthening procedures at more frequent intervals are recommended.35 Another option is epiphysiodesis to the unaffected side, strategically planned to stop growth to allow the CFD side to catch up and decrease the number of lengthening procedures needed.
Rehabilitation Considerations and Programming
Physical therapy is a key part of the limb reconstruction process.33 The rate of distraction, or bone growth during lengthening, is much faster than physiologic growth and results in muscle spasm when the muscles reach the end of their extensibility. Uncontrolled spasms can lead to further muscle shortening, joint contracture, nerve compression, and joint subluxation if aggressive stretches and skilled physical therapy are not performed. The philosophy of therapy during lengthening is very different from that of most orthopedic procedures. Typically, after an orthopedic operation, the patient is at his or her worst immediately following the surgical procedure and gradually improves over time. During lengthening, however, the patient is at his or her best ROM 1 to 2 weeks after the surgical procedure, and as the distraction of the bone progresses, the muscles and soft tissue become tighter, and the ROM decreases. Once the distraction ends, during the consolidation phase, the muscles begin to soften with continued stretches, and the typical pattern of recovery is seen.
In the Paley Advanced Limb Lengthening Institute (West Palm Beach, Fla.)37 treatment protocols for patients in the distraction phase, physical therapy sessions begin with active warm-up, which is accompanied, or followed by, moist heat application to the thigh. Warm-up activities include closed-chain activities to encourage weight acceptance and hip and knee ROM. These activities are followed by open-chain activities using active, active-assisted, and passive ROM. Some of the specific exercises performed include active and passive hip flexion and extension, hip abduction and adduction (not to exceed neutral adduction to minimize risk of subluxation), knee flexion and extension with the hip flexed and extended, and ankle ROM. Electrical stimulation is used as needed to address pain or increase muscle recruitment. Kinesio (Kinesio Precut, Albuquerque, NM) tape can be used as needed to decrease knee pain and facilitate knee motion.
The therapist also performs soft tissue mobilization and progressive stretches. One-joint muscles should be stretched before performing the more aggressive two-joint muscle stretches (e.g., seated knee flexion stretch performed before prone knee flexion stretch). Important muscles that should be stretched three times per day include hip adductors, hamstrings, quadriceps to include rectus femoris, and gastrocnemius. Patellar mobilization is also helpful, because the patella tends to ride high as the rectus femoris becomes increasingly tighter with increased bone growth. All stretches should be performed using short lever arms to reduce the risk of fracture. An important consideration postoperatively is that if the child has had the SUPER hip procedure, the iliotibial band has been removed, and the tensor fasciae latae has been sutured to the greater trochanter to serve as a stronger abductor. If the patient has had a SUPER knee, the iliotibial band has been used to construct extraarticular anterior and posterior cruciate ligaments.
It is important to monitor shoe lift height during therapy and adjust it accordingly during the lengthening, to encourage knee extension with gait and standing. A shoe lift is typically recommended for LLD of less than 10 cm, whereas a pylon and false foot combination is more appropriate for greater discrepancies (Fig. 7-25). However, these parameters have not been addressed in the literature, are more anecdotal, and are based on many years of work with this specialized population.32 The “prosthosis,” which consists of a laminated ankle-foot orthosis (AFO) with a pylon and a prosthetic foot, is sometimes referred to in practice as a cross between a prosthesis and an orthosis. The prosthosis allows for more of a dynamic response during ambulation and is better tolerated by active patients. Use of an AFO may be needed with larger lifts, particularly if the patient also has fibular hemimelia and an unstable ankle. To allow for foot clearance, the lift should be at least 1 cm less than the LLD. The lift should be constructed with a rocker sole to assist forward progression, and a flare at the base allows for greater stability. Multiple tunnels can be drilled into the lift to minimize the weight of a large shoe lift.