What is the purpose of the Ortolani and Barlow tests in assessing hip stability in infants?

Ortolani and Barlow Procedures for Infant Hip Assessment

The Ortolani and Barlow tests are essential clinical maneuvers used to detect developmental dysplasia of the hip (DDH) in newborns and infants, with Ortolani identifying an already dislocated hip that can be reduced back into the acetabulum, and Barlow identifying a hip that is currently in place but unstable and can be dislocated with gentle manipulation. 1

Purpose and Clinical Significance

Ortolani Test

• The Ortolani test detects a hip that is already dislocated by causing the femoral head to slip back into the acetabulum when the examiner abducts and gently lifts the flexed thigh while pushing the greater trochanter anteriorly, producing a palpable or audible "clunk" 1
• This test indicates strong evidence of a severe form of DDH with a completely dislocated but still reducible femoral head 2
• A positive Ortolani sign should be considered an indication for emergency treatment to reduce and stabilize the hip while it is still reducible 2
• The Ortolani test has a high positive predictive value of 39-61% for predicting DDH on subsequent ultrasound examination 3

Barlow Test

• The Barlow test identifies unstable hips that may be missed by the Ortolani test by attempting to dislocate a reduced but unstable hip through a two-step process: first gently adducting the thigh to dislocate the femoral head posteriorly, then lifting the thigh upward while abducting the leg to relocate the femoral head 1
• This test addresses several different forms of hip "instability" that in 80% of cases disappear during growth 2
• The Barlow test has a lower positive predictive value of 4-16% compared to the Ortolani test 3

Underlying Pathophysiology

• Both tests detect instability between the femoral head and acetabulum, indicating ligamentous or capsular laxity that may lead to developmental dysplasia of the hip 1
• The tests assess the dynamic relationship between the femoral head and acetabulum, which can be confirmed through ultrasound examination 2

Age-Specific Reliability and Timing

Optimal Testing Window

• These tests are most reliable in the first 2-3 months of life, as the hip capsule tightens with age, making the tests less sensitive after 3 months 1
• The American Academy of Pediatrics recommends performing these tests at every well-baby visit, particularly at 1-2 weeks and at 2,4,6,9, and 12 months of age 1

After 3 Months of Age

• In children older than 3 months, the Ortolani and Barlow tests become less reliable due to increased tightening of the hip capsule 1, 4
• For children older than 3 months, limitation of hip abduction and asymmetric thigh folds become more useful clinical signs of DDH 1, 5

Critical Distinctions and Common Pitfalls

• It is essential to differentiate between a true positive Ortolani or Barlow test and a benign "clicking" hip, which has no laxity but produces a click during examination 1, 4
• A stable "click" without laxity does not require follow-up, whereas true instability with a palpable clunk demands immediate attention 4
• The sensitivity and specificity of these tests when performed by dedicated examiners is 74-98% and 84-99% respectively, but performance varies significantly based on examiner training and experience 6

Examiner Training and Accuracy

• Results of Ortolani and Barlow tests performed by dedicated hip screeners are significantly better than results performed by routine examiners 7
• The examination requires a distinct tactile feel that is difficult to teach without hands-on training 6
• Pediatric residents perform these tests more frequently than orthopedic residents but may have less confidence in detecting positive findings 6

Risk Factors for False Negative Examinations

• Breech presentation is the only statistically significant risk factor for a false negative Ortolani/Barlow examination (41.2% vs. 13.8% in non-breech infants, p<0.001) 8
• Sonographic hip examinations are recommended for all infants with breech presentation even if they have a normal Ortolani and Barlow examination 8
• The incidence of positive Ortolani and Barlow tests among breech babies is 2.8% 7

Follow-up Imaging Recommendations

When Tests Are Positive

• When Ortolani or Barlow tests are positive, further imaging evaluation is indicated 1
• Ultrasound is the preferred imaging modality for infants under 4-6 months of age, as the femoral heads are primarily cartilaginous 1, 5
• After 4-6 months of age, radiographs become more reliable as ossification progresses 1, 4, 5

Long-Term Implications

• Early detection and treatment of DDH through these procedures can prevent early degenerative joint disease and impaired function 1, 5
• Untreated subluxed and dislocated hips can lead to lifelong disability and early arthritis 1
• Late presentation of hip disorders is a major negative prognostic factor requiring more complex treatment and surgical intervention 5
• The most serious complication of treatment is avascular necrosis, which is a predictor of poor prognosis 1