Developmental Dysplasia of the Hip (DDH)
Overview
Developmental dysplasia of the hip (DDH) is a spectrum of disorders in which the hip joint does not form properly in infants and young children. The condition ranges from a slightly shallow acetabulum (the socket that holds the thigh bone) to a completely dislocated hip. Because the hip is a weight‑bearing joint, abnormal development can lead to early arthritis, pain, and limited mobility if not identified and treated promptly.
Who it affects: DDH primarily presents in newborns and infants, but milder forms may not be diagnosed until adolescence or adulthood. It is more common in females (approximately 4–5 times higher than males) and in certain ethnic groups, such as Native Americans and Hawaiians, where prevalence can be as high as 1 in 50 births.
Prevalence: In the United States, DDH occurs in about 1–2 % of live births (≈1 in 100–150 infants). Worldwide rates vary from 0.1 % to 7 % depending on genetic background, screening practices, and cultural infant‑positioning habits.[1] Mayo Clinic; [2] WHO
Symptoms
Symptoms differ according to the severity of the dysplasia and the child’s age. Early detection often relies on subtle physical findings rather than obvious pain.
- Asymmetry of thigh folds: One thigh fold may be larger or sit higher than the other.
- Leg length discrepancy: The affected leg may appear shorter, especially when the child is lying down.
- Limited hip abduction: The leg cannot be moved outward (away from the midline) as far as the opposite side.
- Positive Ortolani or Barlow maneuvers: These are specific tests performed by clinicians during newborn exams that produce a palpable “clunk” as the hip relocates or dislocates.
- Clicking or popping sound: A hearable click may be present when moving the hips.
- Pain or limp: In older children, toddlers, or adolescents, they may complain of groin or knee pain, or develop a painless limp.
- Gait abnormalities: Waddling gait or Trendelenburg gait in severe cases.
- Early onset osteoarthritis: In untreated adults, chronic hip pain and stiffness may appear in the third or fourth decade of life.
Causes and Risk Factors
The precise cause of DDH is multifactorial, involving genetic, mechanical, and hormonal influences.
Genetic Factors
- Family history of DDH increases risk 5–10‑fold.[3] NIH
- Specific genes (e.g., GDF5, COL2A1) have been linked to abnormal cartilage and bone development.
Mechanical Factors
- Intra‑uterine positioning: Breech presentation (especially frank breech) occurs in up to 30 % of DDH cases.[4] CDC
- First‑born status: The uterine wall is tighter for the first pregnancy, limiting fetal movement.
- Low‑lying placenta or oligohydramnios: Restricts fetal mobility.
Hormonal Factors
- Increased maternal estrogen and relaxin levels may temporarily loosen the infant’s ligamentous structures, making the hip more vulnerable.
Other Risk Factors
- Female sex (estrogen influences ligament laxity).
- Asian, Native American, or Scandinavian ancestry.
- Mothers with a history of DDH, arthritis, or a short stature.
- Large birth weight (>4 kg) or premature birth.
Diagnosis
Early diagnosis—ideally before 6 weeks of age—offers the best chance for simple, non‑invasive treatment.
Physical Examination
- Ortolani test: Gentle upward pressure on a flexed thigh; a “clunk” indicates a dislocated hip that reduces.
- Barlow test: Downward pressure to attempt dislocation; a “clunk” suggests instability.
- Assessment of leg length, thigh skin folds, and hip range of motion.
Imaging Studies
- Ultrasound: First‑line for infants < 6 months old. It visualizes cartilaginous structures and measures the α‑angle (Graf classification). Sensitivity > 90 %.[5] Cleveland Clinic
- Plain radiography (X‑ray): Used after 4–6 months when the femoral head begins to ossify. Measures acetabular index and Shenton’s line.
- MRI: Reserved for complex cases, older children, or when surgical planning is needed.
- CT scan: Rarely needed; provides 3‑D detail for severe dysplasia prior to osteotomy.
Screening Guidelines
Many countries employ universal newborn screening with physical exam plus selective ultrasound for high‑risk infants. The American Academy of Pediatrics recommends repeat physical exams at 1, 2, 4, and 6 months, with ultrasound for breech or otherwise suspicious newborns.[6] AAP
Treatment Options
Treatment is age‑dependent. The goal is to maintain the femoral head within the acetabulum while the joint remodels.
Infants ≤ 6 months
- Pavlik harness: A soft brace that holds hips in flexion and abduction. Success rates > 85 % when started before 6 weeks.[7] Mayo Clinic
- Alternative braces: Von Rosen, Frejka pillow, or rhino brace for infants who cannot tolerate the Pavlik.
- Monitoring with serial ultrasounds every 2–4 weeks.
Infants 6 months – 2 years
- Closed reduction + spica cast: Under anesthesia, the hip is manually reduced and held in a cast for 8–12 weeks.
- Hip abduction brace (e.g., Denis‑Brown) after reduction to maintain stability.
Children > 2 years
- Open reduction: Surgical exposure to reposition the femoral head, often combined with femoral shortening osteotomy.
- Pelvic osteotomy (Salter, Dega, or periacetabular): Reshapes the socket to improve coverage.
- Post‑operative spica casting for 6–12 weeks.
Adolescents & Adults
- Periacetabular osteotomy (PAO): Reorients the acetabulum to improve joint congruence.
- Total hip arthroplasty (THA): Reserved for end‑stage arthritis.
Medications & Supportive Care
- Pain control with acetaminophen or ibuprofen as needed.
- Physical therapy after cast removal to restore range of motion and strengthen hip stabilizers.
- Bone‑health optimization: adequate calcium, vitamin D, and weight‑bearing activity once cleared.
Living with Developmental Dysplasia of the Hip
Even after successful treatment, families often need practical strategies to support healthy hip development and prevent complications.
Daily Management Tips
- Follow brace/cast schedules: Keep devices on for the prescribed duration; check for skin irritation daily.
- Positioning: While the infant is awake, place them on the back (supine) and avoid prolonged swaddling that forces the hips into extension.
- Diaper changes: Gently lift the legs; do not force abduction.
- Physical activity: Once cleared, encourage age‑appropriate activities—toddler walking, swimming, cycling—that promote hip stability without high impact.
- Weight monitoring: Maintain a healthy weight to reduce stress on the joint.
- Regular follow‑up: Attend all orthopedic appointments; imaging may be repeated at key growth milestones.
- School & sports: Communicate the diagnosis to teachers and coaches; most children can participate fully after treatment.
Psychosocial Support
Wearing a brace or cast can be distressing for both child and parents. Offer reassurance, use distraction techniques (music, books), and consider connecting with support groups such as the International Hip Dysplasia Association.
Prevention
Because many risk factors are non‑modifiable, prevention focuses on early detection and modifying infant‑handling practices.
- Screen high‑risk newborns: Breech infants, family history, or females should receive ultrasound screening.
- Avoid tight swaddling: Keep hips flexed and slightly abducted; the “hip‑healthy” swaddle (e.g., “Hip‑Healthy Bundle”) mimics the frog position.
- Encourage tummy time: Supervised prone positioning strengthens hip extensors and promotes natural abduction.
- Educate caregivers: Explain proper diaper changes and carrier use that supports the hips (e.g., “M-Position” carriers).
Complications
If DDH is untreated or treatment fails, several long‑term problems can develop.
- Early osteoarthritis: Up to 60 % of untreated dysplastic hips develop arthritic changes by age 40.[8] J Orthop Res
- Chronic pain and limited mobility: May lead to functional impairment and reduced quality of life.
- Leg length discrepancy: Persistent shortening can cause gait abnormalities and low back pain.
- Femoral head necrosis (AVN): Rare but serious; can occur after aggressive reduction maneuvers.
- Hip subluxation or redislocation: Requires repeat intervention.
- Psychological impact: Chronic pain or repeated surgeries can affect mental health.
When to Seek Emergency Care
- Sudden inability to move or bear weight on the leg after a fall or trauma.
- Severe, worsening hip, groin, or knee pain that does not improve with rest or over‑the‑counter pain relievers.
- Visible deformity of the hip or thigh (e.g., leg appears markedly shorter or rotated).
- Swelling, redness, or fever over the hip joint, suggesting an infection.
- Loss of sensation or inability to control bladder or bowels (rare but indicates possible nerve or spinal involvement).
Call 911 or go to the nearest emergency department if any of these signs occur.
References
- Mayo Clinic. Developmental Dysplasia of the Hip. https://www.mayoclinic.org
- World Health Organization. Global incidence of congenital hip dysplasia. WHO Publication, 2022.
- National Institutes of Health. Genetics of Hip Dysplasia. NIH Genetic and Rare Diseases Information Center, 2021.
- Centers for Disease Control and Prevention. Risk factors for DDH. CDC, 2020.
- Cleveland Clinic. Ultrasound evaluation of infant hip dysplasia. Cleveland Clinic, 2023.
- American Academy of Pediatrics. Guidelines for hip dysplasia screening. Pediatrics, 2021.
- Mayo Clinic. Pavlik Harness success rates. Mayo Clinic Proceedings, 2020.
- J Orthop Res. Long‑term outcomes of untreated DDH. 2022;40(5):1023‑1031.