# A nurse is assessing a 4-month-old infant for developmental dysplasia of the hip (DDH). Which assessment finding would be the most significant indicator of DDH in this infant?

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> subject: Child Health

## 문제

A nurse is assessing a 4-month-old infant for developmental dysplasia of the hip (DDH). Which assessment finding would be the most significant indicator of DDH in this infant?

## 보기

1. Asymmetrical gluteal folds and limited hip abduction on the affected side **✔ 정답**
2. Positive Babinski reflex and increased muscle tone in lower extremities
3. Delayed gross motor development and inability to roll over
4. Presence of Moro reflex and symmetrical primitive reflexes

**정답: 1**

## 해설

Asymmetrical gluteal folds and limited hip abduction are classic signs of DDH in infants, indicating hip instability. Other options are normal developmental reflexes or non-specific findings not directly indicative of DDH.

## 심화 해설

Correct Answer Assessment

The most significant indicator of developmental dysplasia of the hip (DDH) in a 4-month-old infant is asymmetrical gluteal folds and limited hip abduction on the affected side. These are classic physical examination findings directly linked to the pathology of an unstable or dislocated hip joint.

Pathophysiology and Clinical Correlation

DDH encompasses a spectrum of abnormalities where the femoral head has an abnormal relationship with the acetabulum, ranging from mild dysplasia to complete dislocation. The physical examination findings are a direct consequence of this altered anatomy:

- **Limited Hip Abduction (LHA):** Normally, a 4-month-old infant's hip can be abducted to approximately 75 degrees when flexed at 90 degrees. In DDH, the femoral head is displaced posteriorly and superiorly, causing a mechanical blockage against the pelvic bone. This restricts the range of motion, making it difficult or impossible to fully abduct the hip. This is often the most reliable sign in an infant older than 3 months.

- **Asymmetrical Skin Creases (ASC):** As the dislocated femoral head migrates proximally, it shortens the functional length of the limb and alters the soft tissue contour of the thigh and gluteal region. This leads to an apparent leg length discrepancy and uneven folding of the skin, visible as asymmetrical gluteal, thigh, or popliteal folds. While not exclusive to DDH, its presence alongside LHA significantly increases the clinical suspicion.

The provided research confirms that these two physical examination findings—LHA and ASC—are highly correlated with a diagnosis of DDH and facilitate accurate screening [1]. The study emphasizes that a simple physical examination focusing on these signs is critical for early detection.

Analysis of Incorrect Options

- **Option 2: Positive Babinski reflex and increased muscle tone in lower extremities.** A positive Babinski reflex (upward fanning of toes) is a normal finding in infants up to 12-24 months of age and indicates an intact, but immature, corticospinal tract. Increased muscle tone (hypertonia) is a sign of an upper motor neuron lesion, such as in cerebral palsy, and is not a primary indicator of an orthopedic condition like DDH.

- **Option 3: Delayed gross motor development and inability to roll over.** While an untreated, walking-age child with DDH may present with a limp or delayed ambulation, a 4-month-old infant is not expected to roll over consistently. The inability to roll over is a non-specific finding and is not a sensitive or specific early indicator of DDH. The condition is primarily a structural hip abnormality, not a primary neuromuscular deficit that would cause global motor delays at this age.

- **Option 4: Presence of Moro reflex and symmetrical primitive reflexes.** The Moro reflex is a normal primitive reflex that should be present in a 4-month-old infant (it typically integrates around 4-6 months). Symmetrical reflexes are an expected and reassuring neurological finding. This assessment describes a neurologically normal infant and provides no information specific to hip joint stability or alignment.

NCLEX-RN Examination Perspective

For the NCLEX-RN, it is essential to differentiate between normal developmental findings and pathological signs. A nurse must know that the key physical assessment maneuvers for DDH in an infant under 6 months are the Ortolani and Barlow tests. However, these tests become less reliable after 2-3 months of age as soft tissues tighten. By 4 months, the most significant and easily assessed indicators shift to limited hip abduction and asymmetrical skin folds, which are often the first clues noted by a nurse during a routine well-baby examination. The study's findings directly support prioritizing these signs in clinical screening protocols, reinforcing the nurse's role in early identification and referral for confirmatory imaging, such as ultrasound [1].

References (research sources)

- [1]Clinical Examination Findings Can Accurately Diagnose Developmental Dysplasia of The Hip-A Large, Single-Center Cohort.Research articleSubaşı İÖ, Veizi E, Çepni Ş, Alkan H, Oğuz T, Fırat A. (2023) · DOI: 10.3390/children10020304

## 임상 시나리오

Assessing for DDH in the Older InfantKey Physical Exam Findings After 3 Months
In infants older than 3 months, the classic maneuvers for DDH become less reliable as soft tissues tighten. The most significant indicators shift to asymmetrical gluteal folds and limited hip abduction.

To assess abduction, flex the hips to 90 degrees and gently abduct. Normal range is approximately 75 degrees. A mechanical blockage indicates the femoral head is displaced posteriorly and superiorly against the pelvis.

CautionAsymmetrical skin folds alone can be a normal variant in up to 20% of infants. Always correlate with other signs like limited abduction or a positive Galeazzi sign (uneven knee height) to increase diagnostic accuracy.

## 핵심 개념

- **Developmental Dysplasia of the Hip (DDH)** — A spectrum of hip abnormalities where the femoral head has an abnormal relationship with the acetabulum, ranging from mild acetabular dysplasia to complete dislocation.
- **Limited Hip Abduction (LHA)** — A restricted range of motion when moving the leg away from the body's midline, a key physical sign of DDH in older infants due to adductor muscle contracture.
- **Asymmetric Skin Creases (ASC)** — Unequal number or depth of skin folds in the gluteal or thigh region, a secondary sign of leg length discrepancy or hip dislocation in DDH.
- **Barlow Maneuver** — A physical exam technique to detect a dislocatable hip by applying posterior pressure to the adducted hip, most reliable in newborns.
- **Ortolani Maneuver** — A physical exam technique to reduce a recently dislocated hip by abducting the hip and lifting the femoral head back into the acetabulum, typically used in newborns.

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