## Distinguishing Barlow-Positive from Ortolani-Positive Hips ### Clinical Definitions **Key Point:** The Barlow and Ortolani tests assess different pathological states in DDH: - **Barlow test (dislocatable):** Hip is in the socket at rest but can be displaced posteriorly by adduction + flexion + posterior pressure - **Ortolani test (dislocated):** Hip is already out of the socket at rest and can be reduced back in by abduction + flexion + anterior lift ### Radiological Correlates | Finding | Barlow-Positive (Dislocatable) | Ortolani-Positive (Dislocated) | |---------|--------------------------------|--------------------------------| | **Femoral head position at rest** | Within acetabulum | Posterolateral to acetabulum | | **Reducibility** | Can be displaced but returns | Already displaced; requires reduction | | **Shenton line** | Intact at rest | Broken at rest | | **Acetabular index** | May be mildly increased | Markedly increased (>30°) | | **Alpha angle** | >50° at rest | <50° (shallow roof) | ### Why Option 0 is Correct **High-Yield:** The defining radiological feature of a Barlow-positive hip is that the femoral head **remains within the acetabulum at rest** (normal Shenton line, normal alpha angle) but **can be displaced posteriorly** when the specific maneuver (adduction + flexion + posterior pressure) is applied. This is the anatomical hallmark that distinguishes it from a truly dislocated (Ortolani-positive) hip. **Clinical Pearl:** In Barlow-positive hips, static imaging (X-ray at rest) may appear nearly normal because the hip is not dislocated at rest. The pathology is the *instability* and *reducibility*, not the resting position. [cite:Tuli's Orthopedics 6e Ch 8] 
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.