Use of Imaging to Screen for DDH

In addition to the clinical examination, ultrasonography and radiography are also used to screen for DDH.  The use of ultrasonography and/or radiography in screening has been controversial, particularly due to reports of high false positive rates leading to unnecessary and potentially harmful followup and intervention.⁷⁰ Despite the controversy, ultrasound has been widely incorporated into DDH screening programs in many developed countries.^71,72 Ultrasound methods include both static and dynamic assessments of the hip.   As is the case with clinical examination, all imaging methods used to screen for DDH are variably subjective and operator-dependent.

In the first 4-6 months of life, ultrasound has been deemed to be a more appropriate test than radiographs for anatomic hip abnormalities as well as instability of the hip, due to incomplete ossification of the femoral head in early infancy.  No study addressed the comparative value of ultrasound to radiograph.  However, there is strong endorsement of the superiority of ultrasound in the early months of life in the literature, ranging from historical studies reporting on timing of ossification and analyzing the technical challenges of hip radiography in the young infant,^63,73 to contemporary systematic reviews.^1,4

However, ultrasound screening is not without its shortcomings.  In addition to the high rate of identification of nonpathological hip findings summarized above, the most widely used ultrasound-grading system, the Graf classification,⁷⁴ has come under scrutiny.  The Graf score is used in the vast majority of the screening literature to differentiate normal hips from immature hips, minor dysplasia, or major dysplasia; and stable from unstable, subluxable, and dislocatable/dislocated.  Many studies base treatment decisions on these classifications.  A study examining the reliability of Graf classification found that among normal hips, intra- and inter-observer reliability is quite high, with a 98% chance of having the same assessment on future readings.  However, among ultrasounds read as abnormal by at least one person, intra-observer reliability was moderate (kappa = 0.41) and inter-observer reliability was fair (kappa = 0.28).  In addition, knowledge of the patients' history and physical exam vs. blinded review of the ultrasound lowered the intra-observer kappa from 0.41 to 0.37.⁷⁵

Another study found moderate agreement between observers with subjective ultrasound reading (kappa = 0.5), but this decreased to 0.3 when objective measurements of anatomic relationships were conducted.  Grading of dynamic hip stability showed only moderate agreement between examiners (kappa 0.42) even when dislocated and dislocatable hips were grouped together.  This study estimated that the decision to treat would have been affected in 2.4% of cases due to discordance between reviewers.⁷⁶  Considerable effort had been given to standardizing ultrasound assessment in this study, including a training session and 100 repetitions of conducting measurements before the start of the study.  Still another study found ultrasound reliability to be similarly suspect, with kappas ranging from 0.52 -0.68 and 0.09 to 0.30 for intraobserver and interobserver agreement, respectively, across seven anatomic measures used in grading DDH.⁷⁷  These findings raise concerns about the operator dependence of this evaluation for DDH, and may shed light on the variability of ultrasound screen positive rates found in the literature.

 While there are no trials or comparative studies of a screened to an unscreened population, 2 randomized controlled trials^78,79 and 1 nonrandomized controlled trial⁵³ provide some insight into the accuracy of clinical and ultrasound examinations.  These trials reported data about test performance of one screening strategy versus another (Table 2).  The first randomized controlled trial (RCT) compared universal ultrasound screening to selective screening at a population level.⁷⁸  In the trial, patients at the University of Trondheim, Norway were randomized over a 5 year period to one of two groups.  In the first group, each of the 7840 patients received clinical exam and ultrasound.  In the other group, 7689 received clinical exam alone or, if they had risk factors (abnormal exam, breech, family history, foot deformities), ultrasound and clinical exam.  In the selective ultrasound group, 5 infants presented between 5-6 months with previously undiagnosed DDH, whereas in the universal screening group there was only 1 case of late diagnosis.  In all these late-presenting cases, treatment with an abduction brace was implemented and the hips were reported to be normal upon followup, with none requiring subsequent surgery.  Overall treatment rates were equivalent in the two groups.

The second RCT⁷⁹ included 629 patients who had been diagnosed with unstable hips on screening examination and were referred to 33 specialty centers in the United Kingdom (UK).  The subjects were randomized within the specialty centers to receive ultrasonographic hip examination (n=314) or clinical assessment alone (n=315).  A total of 90% of patients in the ultrasound group received an ultrasound in the first 8 weeks of life; 8% in the no-ultrasound group received an ultrasound.  Compared to those in the ultrasound group, infants in the no-ultrasound group were treated more often (50% vs. 40%) and earlier (98/150 vs. 42/117 treated in the first 2 weeks of life).  The need for surgical treatment (8% vs. 7%), age at surgical treatment (31 vs. 29 weeks), mean number of visits at outpatient clinics (4 in each), total hip-related hospitalizations (30 vs. 23) and the occurrence of definite or suspected avascular necrosis (5 vs. 8) were not significantly different between the two groups.  Thus, despite a higher rate and earlier initiation of treatment in the clinical examination only group, the non-functional "outcomes" of the two groups were quite similar.  This suggests that, in the specialty setting, clinical examination alone may lead to a greater degree of unnecessary treatment than that which occurs when an abnormal clinical examination is followed up with evaluation by ultrasound.

A nonrandomized controlled trial conducted in 1994 compared 3613 infants in a universal ultrasound screening program to 4388 in a selective screening program, and 3924 who received only clinical examination.⁵³  In the selective ultrasound cohort, a positive clinical examination was considered to be a risk factor prompting ultrasound.  The authors concluded that the universal ultrasound cohort had a significantly higher treatment rate overall, but no higher rate among high risk infants.  There was a nonsignificant trend toward a lower rate of cases diagnosed after 1 month of age in the universal screening patients.  Among those not treated, many more children with mildly dysplastic hips were identified by ultrasound, resulting in more followup visits and ultrasounds for a greater number of patients without persistent DDH in the universal screening approach.

Table 3 includes studies of population-based or primary care clinic-based cohorts screened by clinical examination as well as ultrasound screening, published since the 1996 endpoint of the AAP review.^{28,70,72,80-83}   Despite variation in the reference standards used in these studies, several important findings emerge.  First, a high proportion of hips diagnosed with minor findings of dysplasia undergo spontaneous resolution. It is important to note that minor dysplasia is not identified by clinical exam, but only by ultrasound.  Due to the identification of anatomic variations that are marginal and self-limited, the potential exists for over-treatment on the basis of ultrasound.  On the other hand, in 4 of the 7 studies in Table 3, 38%-87% of abnormal findings on clinical exam were not DDH, leading to a similar risk of unnecessary therapy on the basis of clinical examination.^72,80,81,83 Very few of these studies followed patients longitudinally, particularly those patients who did not screen positive by exam or ultrasound.

Key Question 4.  What Are the Adverse Effects of Screening?

Dislocation

While it has been suggested that the examination of already-lax newborn hips might cause injury or dislocation,⁸⁴ we identified little research that sought to test this hypothesis.  Three studies provide some insight.^85-87  An autopsy study examined 10 hips in stillborn infants, 4 of them full term and one at 28 weeks gestation, and found that after repeated (up to 30) "forceful" (amount of force not quantified) Barlow maneuvers six of the hips became lax.⁸⁵ Upon further study, it was determined that if the vacuum present in the joint capsule is disrupted, the hip becomes readily dislocatable.⁸⁵ A second study used an anatomic hip model and examiners ranging from clinicians with "many years" of experience to pediatric home visiting nurses who had just completed a training course in hip examination.  This study reported that the average maximum force applied during the Barlow maneuver was 3 times that necessary to dislocate a dislocatable joint, and was consistently excessive across all levels of experience.⁸⁶ A study with living patients used dynamic ultrasound to monitor laxity during 4 successive examinations with Barlow and Ortolani and found no increased laxity over the course of these exams.⁸⁷   However, different examiners conducted each exam, so within-subject trends in stability may reflect differences between examiners as much as changes in the joints themselves.⁸⁷

Radiation Exposure

A single center study of radiation exposure and increased theoretical risk of fatal cancers or reproductive defects reported the radiographic history of 173 patients who completed a course of treatment for DDH between 1980 and 1993. Based upon cumulative radiation exposure, males and females with DDH who had surgery (a marker for significantly elevated levels of exposure) were calculated to have a 0.09% and 0.12% increased risk of fatal leukemia and a 0.23% and 0.5% increased risk of reproductive defects, respectively.⁸⁸ There was no increased risk of fatal breast cancer in either gender.  Attributable risks in nonsurgical DDH patients were approximately 1/2 to 1/3 of those reported for surgical patients.  Given changes in technology and management in the time interval since this data was gathered, it is not clear whether the level of radiation exposure documented in this study is still applicable.

Psychosocial

We found no published studies that sought to identify or quantify the psychosocial stresses of the diagnosis of DDH.  No evidence was identified regarding adverse effects suffered by the child or family from false positive identification.  Presumably, there is a cost borne by the family and/or society for the followup evaluation that ensues, but this has not been quantified.  Other adverse effects may be experienced, but are not represented in the literature.

Key Question 5.  Does Early Diagnosis of DDH Lead to Early Intervention, and Does Early Intervention Reduce the Need for Surgery or Improve Functional Outcomes?

10 different nonsurgical abduction devices are represented in the published literature and 23 different surgical procedures are used to treat DDH (see Evidence Report¹² for a complete listing).  The indications and timing of treatment, and the protocol for the selected treatment modality vary from study to study, further obfuscating attempts at clarifying effectiveness.  These circumstances are characteristic of interventions that have not been evaluated, or proven effective, in controlled trials.⁸⁹ Because no experimental or prospective cohort studies compare intervention with no intervention, the net benefits and harms of interventions for DDH are unclear, not only for infants diagnosed early but for all children.⁹⁰ 

Poor functional outcomes from hip pathology may not manifest for decades.  Thus, functional outcomes have not commonly been measured.  Even when measured, the effect of interventions on functional outcomes is unknown because of:

1. The absence of an appropriate comparison cohort.
2. The substantial risk of bias stemming from short duration of followup, significant loss to followup, and/or nonstandardized, unblinded assessment methods without adequate rigor to ensure their validity (e.g., the surgeon's subjective report of the patient's function and pain).

Due to these methodological problems, the evidence assessing whether interventions improve functional outcomes is poor, and study details have been excluded.  Details about intervention studies^91-103 that included any assessment of functional outcomes are included in the Evidence Report.¹²

Given the absence of direct evidence from controlled trials, the case for the effectiveness of early intervention rests on less secure grounds, as follows:

1. Biological Plausibility

  It is biologically plausible that placing the femoral head into the acetabulum would facilitate normal development.  While they are retrospective, careful analyses of late-presentation cases provide convincing fair quality evidence that late-presentation dislocations are often accompanied by premature arthritis, indicating that, at least in some cases, untreated DDH can have serious consequences.^104-106

Based on this information, it is reasonable to hypothesize that relocating hips long before clinical symptoms occur may prevent morbidity and improve function.  Unfortunately, an understanding of the effectiveness of interventions for DDH is confounded by the fact that many unstable and dysplastic hips undergo spontaneous resolution.¹⁰  Thus, without a study design that includes an untreated cohort, the benefit attributable to an intervention remains in doubt. 

Although the number of studies is small, it is clear that untreated DDH has an unpredictable course, with outcomes that are not universally poor.  Among 628 Navajo infants born in a single region from 1955 to 1961, 548 were examined and radiographed during the first four years of life (20% in the first 6 months of life, but none as neonates).^107,108  Eighteen (3.3% of those examined) were found to have hip dysplasia (including subluxation, but not including frank dislocation) by accepted radiographic criteria.  None were treated.  Seventeen of these 18 children were followed for seven to 19 years, and all had stable hips with normal x-rays.¹⁰⁸  When 10 of these patients were followed up at 33-37 years of age, none were aware that they had ever had a problem with their hips.  While 6 did report a history of mild hip pain, this did not correlate with the degree of abnormality on x-ray.  Additionally, all patients had normal function, engaged in light to heavy labor and were able to contribute to society without limitations.¹⁰⁷  Another study followed 51 consecutive patients with a normal clinical examination but evidence of dysplasia on x-ray.  Altogether, 6 patients were lost over 5 years of followup.  Forty-four affected hips (number of patients not reported) were normal after 5 years, 4 had undergone successful abduction therapy, and 20 were borderline on repeat imaging.  No progression to subluxation or dislocation was noted in any of the hips.¹⁰⁹

2. Reduced Need for Surgery

  Early noninvasive intervention may reduce the need for surgery.  This is a key observation that underlies previous recommendations favoring screening for DDH.  As discussed earlier, however (KQ1), the evidence supporting this assertion is conflicting.  More over, the need for surgery is a moving target:  when they are observed, reductions in surgical rates might have occurred because of changing indications or because of wider use of a period of observation prior to surgery, rather than because of screening itself.

Earlier intervention may reduce the risk of complications.  Several observational studies examined the impact of age at the time of intervention.^{25,81,95,110-113}   In one small study that included children initiating therapy for DDH from birth through 4 months of age, duration of treatment increased in a dose response fashion as the age at initiation of treatment increased, holding the severity of DDH steady.⁸¹  In a separate series of patients undergoing surgery for DDH (70% of whom had failed therapy with a Pavlik harness), those 6-9 months of age (18 patients) required no additional corrective surgeries, whereas 29% of  patients 10-11 months of age, 13% of patients 12-14 months of age, 26% of patients 15-18 months of age, and 30% of patients 19-24 months of age required additional surgical interventions.¹¹⁰  Another study, based upon unadjusted analysis, reported that the average age of DDH cases complicated by avascular necrosis was > 15 months, whereas uncomplicated cases averaged 11 months of age.¹¹¹ Two additional studies found that intervention initiated after 6 months of age was associated with significantly higher rates of avascular necrosis.^95,112 In a study that focused on late diagnosis of DDH, closed reduction failed in a similar proportion of cases in children 0-3 months as those 3-6 months, but failed significantly more frequently after 6 months of age (no upper age limit was identified, potentially biasing these conclusions).¹¹³  Finally, a study of 55 children who underwent operative procedures for DDH between 1988 and 1998 found that procedures were less invasive in children less than 6 months.  All children greater than 12 months undergoing a procedure for DDH required an osteotomy, the most invasive procedure.²⁵ While inconclusive, these studies provide fair evidence that initiation of interventions after 6 months of age may carry added risks of harms.

In contrast, three retrospective observational studies did not support an effect of age on success of treatment.^94,114,115  The first reviewed the rate of success of closed reduction, and showed no difference among patients treated with this intervention at less than 6 months, 7-12 months, or 13-18 months.¹¹⁴  A study limited to 168 children with hip subluxation or dislocation and a minimum follow up of 5 years, compared children in whom a Pavlik harness was successful with those requiring closed reduction and those who eventually required open reduction, and found that age was not a predictive factor of the success of nonsurgical therapy.¹¹⁵  Finally, a study of 75 children with DDH treated within the first 14 weeks of life with the Pavlik method showed that age at initiation (ranging from 5 to 13 weeks) had no influence on duration of treatment, success rate, or AVN outcome at 1 year of age.⁹⁴

It is possible that some relevant literature was excluded because we limited the review to studies in children whose intervention began within their first year of life.  Within this period, conclusive evidence of a clear benefit of earlier intervention is elusive.  The design of the studies cannot exclude other plausible explanations for the association between age at intervention and rates of surgery.  One of these explanations is that passive abduction therapy may be less effective as children become stronger and more mobile beyond 6 months of age.  Another is that the early-treated group includes a high proportion of children with mild disease that would have recovered without intervention, while the older children have persistent disease that would not have responded even if they had been treated earlier.

3. Improved Radiographic Appearance

Use of noninvasive treatments is often associated with improvements in radiographic or sonographic appearance.  While radiographic reduction may be an essential step in the causal pathway from congenital dislocation to prevention of serious complications, radiographic outcomes have not been shown to be valid or reliable surrogates for functional outcomes.   The most commonly used and widely accepted radiographic assessment is a 6-level scale initially described by Severin in 1941, based upon radiological appearance of hips in 16-24 year olds.¹¹⁶ One study examined the validity of the Severin classification with functional outcomes in patients who had received surgery for dislocation of the hip, at an average of 31 years post-intervention.¹¹⁷ The study found that x-ray findings (normal position of femoral neck and head, degree of arthritis and shape of the femoral head) were poorly correlated with the outcomes of range of motion and pain. 

Two studies assessed the reliability of the Severin classification.^118,119  Ali et al found intraobserver reliability among pediatric orthopedists in the UK with 7 or more years experience to be moderate to substantial (kappa ranging from .58 to .77), and interobserver reliability to be poor to slight in the intermediate Severin classes of II and III (kappa 0.19 to 0.20) and moderate (kappa 0.44 to 0.54) in the disparate Severin classifications of I (normal) and V (marginal dislocation). Ward found even less reassuring results.¹¹⁹  Blinded assessments by pediatric orthopedists in this study were assessed by dichotomous observer groups as well as multi-rater groups, and found kappa scores in the range of 0.0 to 0.29 across the range of Severin classes, and no higher than 0.56 for overall agreement across any two surgeons.  Even more concerning, the operating surgeon's unblinded scores showed uniform poor reliability (kappa 0.02 to 0.21) when compared to each of the blinded observer's scores.  Despite the absence of studies supporting the reliability of radiographic measures, intervention studies rarely included blinded or repeated assessments of radiographic outcomes.  Due to highly suspect validity and reliability, studies that reported only radiographic outcomes were excluded from further review.

4.  Closer Followup

Diagnosis leads to attentive followup of infants with DDH, facilitating quick detection and intervention.  Thus, children undergoing early noninvasive therapy may benefit from closer followup and the physician's ability to react to a deteriorating condition more rapidly.  Though limited, available evidence supports the notion that a high proportion of families follow through with initial referral.²⁹ However, we could not determine how many families adhere to ongoing followup. 

Underlying the effectiveness of early diagnosis and early intervention is the degree to which families adhere to medical recommendations.  One study assessed failure to followup with a specialty appointment after identification of newborns with an abnormality on exam or the presence of a risk factor for DDH.²⁹ This specialty clinic, a part of Britain's National Health System, followed a systematic approach to contacting non-attenders, including up to 2 letters to the family explaining the reason for referral, safety of ultrasound, and offering an appointment the following week, followed by contact with the general practitioner to persuade the family.  With this approach, nearly 95% of patients followed up.  The groups with the highest followup rate (>98%) included those with an unstable hip at the newborn exam and those with a positive family history. It may be unlikely that the average orthopedic clinic in the United States will achieve an equivalent rate of followup, given access barriers and less robust efforts at contacting those who initially miss scheduled appointments.

A second study, based in the U.S., examined the rates of parental adherence to recommended abduction therapy with the Pavlik harness.¹²⁰ Of 32 patients treated by the same physician, only 2 families reported strict adherence to the physician's orders in a post-treatment questionnaire.  Nonadherence was defined as failure to do one or more of the following:

1. Full-time use during the initial period of reduction when the hip was not stable.
2. Altering or deliberating misplacing the harness.
3. Discontinuing use of the harness for prolonged periods of time without permission.

Nearly two-thirds of the mothers participating in the study had a college education or advanced degree; their age range was 17-40 years (average age 29 years).  Harness therapy failed in 3 out of the 32 patients, and by the authors' report these cases were not more egregious in their degree of noncompliance than successfully treated children.  The single exception was a mother who routinely removed or adjusted the harness because the child could not fit into a car seat due to limited adduction.¹²⁰

Key Question 6.  What Are the Adverse Effects of Early Diagnosis and/or Intervention?

Good quality literature examining harms of intervention for DDH would include a comparison of 2 or more (ideally randomized) cohorts, each exposed to a standardized intervention and followed over sufficient time (with limited loss to followup) to ensure complete ascertainment of the potential harms with an assessment of the effect of the measured harms on patient outcomes.  Unfortunately, these studies have not yet been conducted.  In their absence, we reviewed the fair quality literature on adverse effects of both nonsurgical and surgical interventions.

The most well described adverse effect from interventions aimed at treating DDH is AVN of the femoral head.  This is the most common adverse effect for both abduction therapy and surgical interventions.  AVN severity ranges from a persistent but asymptomatic radiographic finding to a severe condition that causes growth arrest and can lead to eventual destruction of the joint.  The rates described in the literature for AVN vary greatly for abduction therapy as well as surgical interventions. (Figure 3).^{91-95,97,99,101-103,112,121-129}  The reasons for these disparate findings are not straightforward, and most likely relate to a complex and confounded set of variables including but not limited to the wide spectrum of the disorder, heterogeneous populations studied (age at intervention, specific type of DDH, previous interventions received), the variety of interventions and the poorly standardized approach to interventions (particularly the pre- and post-intervention phase of management), variable training and talent among the treating physicians, different lengths of followup across studies, and disparate approaches to followup in different health care systems.  As calculated in the AAP review, meta-analytic rates of AVN range from 13.5-109/1000 infants who undergo treatment (non-surgical vs. surgical rates not specified).¹

Additional harms from abduction therapy that have been addressed in the literature are typically mild and self-limited, and include rash, pressure sores, and femoral nerve palsy. All surgical interventions carry the risks inherent in general anesthesia, and those that involve open surgery also include the generic surgical risks of infection, excessive bleeding, and wrong site surgery, though these receive scant review in the published literature and thus cannot be quantified.

A fair quality study assessing the long-term psychological impact on children of successfully treated DDH showed that parents and teachers found that children with DDH were more "disordered" than peers with no hospitalizations, 1 hospitalization, and multiple hospitalizations on the domains of "health," "habits," and "behavior."¹³⁰ This 1983 study implies (but does not quantify) extended hospitalizations for children with DDH as a rule, and thus may not be generalizable to the impact of treatment today.

Key Question 7.  What Cost-effectiveness Issues Apply to Screening for DDH?

Several economic analyses of screening for DDH have been published.^{79,90,131-136}  Most concern the marginal benefit of ultrasound screening in relation to screening with clinical examination.^{79,90,132,133,136} None of the available studies used quality adjusted life years, and none used models based upon U.S. data or the U.S. health care system. These analyses demonstrate that the economic impact of ultrasound screening is complex, reflecting that ultrasound may have mixed effects on diagnosis of DDH:  it may identify false positive clinical examinations, reducing or shortening the duration of unnecessary treatments, but it also identifies many abnormalities in infants who have normal physical examinations, potentially leading to more early treatment and greater followup costs. The mixed results of the economic studies largely reflect mixed results of the clinical studies on which they are based.  The best quality economic study, derived from a RCT (in the U.K.) of clinical exam screening versus clinical exam plus ultrasound, maintained detailed records of utilization of medical services and related costs.⁷⁹ While the costs of ultrasound were predictably higher in the cohort receiving ultrasound, hospitalization costs in this group were lower.  In sum, the overall direct medical costs for the two approaches were not statistically significantly different.⁷⁹ This study did not report indirect costs, such as missed work by the family, nor did it include the costs of long-term followup or complications.

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Discussion

As a condition that can result in impaired functional outcomes for children and adults, DDH merits the attention of primary care clinicians.  However, there is no direct evidence that screening improves functional outcomes, and the evidence for several links in the analytic framework is weak.  Table 4 summarizes the quality of the evidence.

The definition of DDH is variable, including dislocated, dislocatable, subluxable, and dysplastic hips.  The benefits of early intervention are based on expert opinion along with mixed evidence that later diagnosis results in a greater likelihood for surgical intervention, and more complications.  Using indirect comparisons, some studies suggest that earlier diagnosis is associated with better results, but these findings could be the result of lead-time bias, that is, the identification of DDH in a group of younger patients, in whom a higher rate of spontaneous resolution may lead to better outcomes, rather than the effect of earlier intervention. The outcomes of screened infants have not been compared to those of unscreened infants in an experimental or observational study. 

Despite a paucity of evidence supporting its value in improving outcomes, universal screening for DDH is a well-established approach to the disorder.  However, the approach to screening varies significantly.  In addition to physical examination with the provocative tests of Barlow and Ortolani and evaluation of range of motion emphasizing abduction of the hip, static and dynamic ultrasound are employed to identify anatomic abnormalities and stability of the hip, respectively.  Some have recommended risk stratification to inform selective use of ultrasound, with females in breech positioning at delivery found to have the highest rate of clinical hip instability (84/1000). Yet, when a more conservative reference standard for DDH is employed, the value of ultrasound as an aid to diagnosis in those with risk factors is less conclusive.  Some health systems have elected to employ universal ultrasound screening in an effort to reduce the incidence of late diagnosis of DDH.  The use of ultrasound to further evaluate hips found to be unstable on clinical exam may reduce the rate of unnecessary treatment, but may also lead to higher rates of followup for hips that will ultimately spontaneously normalize.  The reliability of DDH classification by ultrasound is questionable.  Theoretical harms from screening include examiner induced hip pathology with vigorous provocative testing, elevated risk of certain cancers from increased radiation exposure from followup radiographic tests, and parental psychosocial stress from the diagnosis and therapy.  None of these has been quantified in patients/families in clinical studies published to date beyond anecdotes.

It is known that a significant number of hips with positive screening tests, both by physical examination and by ultrasound, will normalize over time without intervention.  This is particularly true of ultrasound in hips that are stable on clinical exam of the neonate: more than 90% of abnormal ultrasound findings in this situation have been shown to normalize spontaneously. While limited fair quality evidence exists to support the value of initiating treatment within the first 6 months of life, there is little to suggest that immediate treatment in the neonatal period is associated with improved outcomes or a reduced need for subsequent surgery. However, no study has examined the effect of timing of treatment initiation, controlling for the degree of hip instability.

First-line intervention includes abduction bracing of the hips, which attempts to induce passive alignment of the hip.  Several devices are used for abduction, with a wide range of institutional protocols.  Failure of abduction therapy, or the occasional case of dislocated and clinically irreducible hips at presentation, leads to surgical intervention.  The indications and protocols for surgery vary widely, as do the pre- and post-operative approaches to management. 

Estimates of the effectiveness of therapy are confounded by spontaneous resolution of hip dysplasia, which has only rarely been assessed and never in a prospective or comparative fashion.  The impact of interventions on functional outcomes is rarely addressed in the literature, and when addressed is of poor quality due to a lack of standardization within studies, and the absence of validated functional outcome measures across studies.

The most significant and common adverse effect of both nonsurgical and surgical intervention for hip dysplasia is avascular necrosis of the femoral head, which can lead to growth arrest and eventual destruction of the hip joint.  The balance of benefits and harms of intervention is obscured by significant gaps in the available evidence.  Assessment of the cost effectiveness of screening for DDH similarly requires more conclusive information about effectiveness.

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Future Research

While the body of literature on screening and intervention for DDH has significant flaws, several recent studies provide valuable information on the screening evaluation of DDH.  However, conclusive evidence is still absent.  A more complete understanding of the natural history of spontaneous resolution of hip instability and dysplasia is needed to develop an evidence-based strategy for conducting screening and implementing therapy at the optimal time.  Given the infrequent nature of DDH, multicenter studies of interventions that measure functional outcomes in a standardized fashion are needed.   Studies designed to assess whether any clearly defined, reliable radiological markers predict functional outcomes would be a valuable step.  Even more valuable would be patient-centered research that seeks to understand patient and family preferences as they relate to the process of care and short and long-term outcomes of DDH.

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