Basics
Description
Developmental dysplasia of the hip (DDH) is a range of hip pathology including dysplasia (shallow acetabulum), subluxation (partial femoral head-acetabulum contact), and dislocation (no hip joint contact). Abnormalities can be present at birth or develop over time. A teratologic dislocation is a different condition that occurs during fetal development usually from genetic/syndromic causes. Discussion of teratologic dislocation is beyond the scope of this chapter.
Epidemiology
- Female-to-male ratio is 4:1.
- Incidence varies from 1.5 to 25 in 1,000 births.
- Dislocation incidence is about 1 in 1,000 births.
Risk Factors
- Compressive factors:
- Breech position (newborn DDH risk: male 2.6%, female 12%)
- Oligohydramnios
- Firstborn child
- High birth weight
- Demographic factors:
- Female gender (newborn DDH risk 1.9%)
- Family history (newborn DDH risk: male 0.9%, female 4.4%)
- Ethnicity: Native American, Laplander
Genetics
No defined mode of inheritance; family history, gender, and ethnicity association
General Prevention
Although DDH cannot be prevented, treatment is directed at preventing early arthritis. Screening programs have reduced the newborn dislocation rate to 1 in 5,000 children by the age of 18 months.
Pathophysiology
The acetabular depth (growth) is determined by healthy cartilage and development around a concentrically reduced/stable femoral head. Cartilage damage occurs from continued instability. Untreated subluxation/dislocation can result in an everted labrum, hypertrophic cartilage/labrum complex (neolimbus), and false acetabulum (pseudoacetabulum). In early adulthood, this can lead to abnormal wear of the joint, limb length differences, and arthritic pain. Compensatory problems may include spinal malalignment (scoliosis/lordosis) and gait abnormalities.
Etiology
- Mechanical factors: attributed to a smaller in utero environment from oligohydramnios, breech position, increased birth weight, or an unstretched uterus (first pregnancy)
- Female predominance: attributed to estrogen-induced ligamentous laxity
- Left side predominance: attributed to fetal positioning of left hip adduction against the mother's lumbosacral spine
- Native American predominance: attributed to the hip extension/adduction position of swaddling
Commonly Associated Conditions
- Neurologic conditions (e.g., myelomeningocele)
- Connective tissue disorders (e.g., Ehlers-Danlos)
- Syndromic conditions (e.g., Larsen syndrome)
- Myopathic disorders (e.g., arthrogryposis)
Diagnosis
History
Gestational age, gender, birth weight/order, delivery method/position (breech), and family history (DDH or associated conditions [see earlier]) should be asked.
Physical Exam
- Ensure that the child is relaxed and calm.
- Screening should be done at all well-child visits until normal ambulatory development.
- Newborn exam
- Hard signs (<3 months old):
- Ortolani test: The contralateral hip is flexed, abducted, and held with one hand to stabilize the pelvis. The other hip is held with the thumb in the groin crease and the index/middle finger over the trochanter. With the hip flexed (90 degrees), the trochanter is lifted (anteriorly) as the hip is abducted. An unstable hip will "clunk" as it reduces.
- Barlow test: similar hand position as the Ortolani test. The hip is flexed (90 degrees), and as the hip is adducted, a posterior stress is applied. An unstable hip will palpably slip out of socket.
- Galeazzi sign: With bilateral hip and knee flexion, an asymmetry in knee height occurs from apparent femoral shortening on the dislocated side.
- Soft signs:
- "Packaging" abnormalities: torticollis, limb deformity (metatarsus adductus), joint contractures, or dislocation of other joints
- Asymmetric skinfolds (low sensitivity)
- Sacral dimple
- Ambulatory child exam:
- Stiffness: limited abduction (normally abduction >75 degrees, adduction >30 degrees)
- Limb length difference: unilateral toe walking, abnormal Galeazzi sign, scoliosis
- Gait: lurching to one side (Trendelenburg gait)
- Bilateral dislocation: may have waddling gait and hyperlordosis. Galeazzi sign will be normal. May be difficult to recognize.
Alert
- Early diagnosis and referral are paramount.
- Main instability indicators are the Barlow and Ortolani exams. Perform these gently.
- Soft tissue clicks superficial in sound and most asymmetric thigh folds are normal.
- An unreducible hip may have a falsely normal Ortolani/Barlow exam but will be Galeazzi positive.
- Exam and risk factors guide future screening and referral.
Diagnostic Tests & Interpretation
Imaging
- If the clinical exam findings are clearly abnormal, then refer the patient. No further imaging is needed for referral.
- Imaging is used to clarify an equivocal examination and to monitor treatment progress.
- Ultrasound
- Optimal age: 3 weeks to 5 months
- Static examination: Superior acetabular coverage (α-angle) and femoral head position (β-angle) can be assessed.
- Dynamic examination: assesses stability
- Plain radiographs (AP pelvis ± frog lateral)
- Optimal age: after 3-6 months
- CT scan/MRI
- Used to assess concentric hip reduction after orthopedic surgical intervention
Differential Diagnosis
- Septic hip
- Congenital coxa vara
- Proximal femoral focal deficiency
Treatment
Additional Treatment
General Measures
- Treatment principle: Acetabular remodeling potential rarely exists after 4 years of age. When remodeling potential exists, treatment goals are to redirect the femoral head into the acetabulum with minimal force while avoiding complications of avascular necrosis and cartilage damage.
Issues for Referral
Primary care providers (PCPs) algorithm of care:
- Initial (newborn) exam
- Abnormal (hard exam findings): orthopedic referral
- Inconclusive (soft exam findings only): send for ultrasound after 2-3 weeks of age. If abnormal, refer.
- Normal exam
- If no risk factors: Reexamine at every well-child visit until normal ambulatory development.
- If lower risk (female, male with family history):
- Reexamine during well-child visits until normal ambulatory development.
- If intermediate risk (female with family history, male born breech):
- Consider future imaging: ultrasound (~4-6 weeks), radiographs (~6, 12 months)
- If intermediate risk (female with breech position)
- Obtain future imaging: ultrasound (~4-6 weeks) and radiographs (~6, 12 months)
- Follow-up (postnewborn) exam: if abnormalities exist after the initial newborn period, then referral with ultrasound (if <5 months of age) or radiographs (if >4-6 months of age)
Additional Therapies
Pavlik Harness
- Indications: if earlier criteria is met for referral but referral is not possible and child is <6 months of age or the PCP is trained in Pavlik harness use
- NOTE: Abduction brace (more rigid) can be used if treatment extends past 6 months of age when the child becomes more ambulatory.
- For a hip that reduces:
- Place harness full time with joint reduced (may confirm with ultrasound).
- Reexamine hips and readjust harness every 3 weeks.
- Repeat ultrasound ~6-12 weeks.
- Once hip exam is normal, continue full-time Pavlik use for additional 6-12 weeks.
- Radiograph at 6, 12 months
- For hip dislocation (nonteratologic):
- Follow the earlier protocol except
- Initial ultrasound and radiographs for documentation of dislocation
- Clinically reassess every 7-10 days until hip reduces.
- If hip reduces, document with ultrasound.
- Radiographs at 3 months
- Refer patient and abandon harness treatment if not reduced by 3 weeks.
- Pavlik harness application:
- Chest strap: nipple level, snug
- Shoulder strap: should cross posteriorly, snug
- Stirrup: should start distal to the popliteal fossa
- Anterior strap: midaxillary line strap adjusted so hip is flexed at 90-100 degrees
- Posterior strap: attaches over the scapula, adjusted so hips do not adduct (do not force abduction)
Alert
- Pavlik harness use is safe when properly placed.
- Never force the hip into position.
- Improper use can lead to cartilage damage, femoral nerve palsy, and avascular necrosis.
Surgery/Other Procedures
- Closed reduction: used when Pavlik harness treatment fails. Spica cast is applied for 2-6 months.
- Open reduction: used when closed reduction fails usually due to soft tissue interposition and/or muscle contracture. Common after 6 months of age. Adductor tenotomy is usually done. Spica cast is applied after.
- Osteotomy: After about age 2 years, excessive force is needed for a closed/open reduction. Femoral osteotomy reduces this risk along with an open reduction. For residual dysplasia, acetabular osteotomies are performed.
Ongoing Care
Follow-up Recommendations
Patient Monitoring
See "Issues for Referral" section.
Prognosis
- 95% successful resolution of an abnormal Ortolani exam when Pavlik harness treatment is initiated in a newborn
- 85% success when the same treatment is started after 1 month of age
Complications
- Pavlik harness
- Tight shoulder strap: brachial plexopathy
- Hip hyperflexion: femoral nerve palsy, inferior dislocation
- Forced abduction: femoral head damage resulting in growth arrest or avascular necrosis. Growth arrest can cause trochanteric overgrowth and abductor lurch.
- Poor hygiene: skin breakdown (groin crease and popliteal fossa)
- Failure or lack of treatment: residual dysplasia/instability/growth arrest resulting in limb length difference, scoliosis/lordosis, arthritis, gait disturbance, and toe walking
Additional Reading
- American Academy of Pediatrics. Clinical practice guideline: early detection of developmental dysplasia of the hip. Pediatrics. 2000;105(4, Pt 1):896-905. [View Abstract]
- American Institute of Ultrasound in Medicine. AIUM practice guideline for the performance of an ultrasound examination for detection and assessment of developmental dysplasia of the hip. J Ultrasound Med. 2013;32(7):1307-1317. [View Abstract]
- Guille JT, Pizzutillo PD, MacEwen GD. Developmental dysplasia of the hip from birth to six months. J Am Acad Orthop Surg. 2000;8(4):232-242. [View Abstract]
- Mahan ST, Katz JN, Kim YJ. To screen or not to screen? A decision analysis of the utility of screening for developmental dysplasia of the hip. J Bone Joint Surg Am. 2009;91(7):1705-1719. [View Abstract]
- Nemeth BA, Narotam V. Developmental dysplasia of the hip. Pediatr Rev. 2012;33(12):553-561. [View Abstract]
- Storer SK, Skaggs DL. Developmental dysplasia of the hip. Am Fam Physician. 2006;74(8):1310-1316. [View Abstract]
- Vitale MG, Skaggs DL. Developmental dysplasia of the hip from six months to four years of age. J Am Acad Orthop Surg. 2001;9(6):401-411.
- Weinstein SL, Mubarak SJ, Wenger DR. Developmental hip dysplasia and dislocation: part I. Instr Course Lect. 2004;53:523-530. [View Abstract]
- Weinstein SL, Mubarak SJ, Wenger DR. Developmental hip dysplasia and dislocation: part II. Instr Course Lect. 2004;53:531-542. [View Abstract]
- Westacott D, Pattison G, Cooke S. Developmental dysplasia of the hip. Community Pract. 2012;85(11):42-44. [View Abstract]
Codes
ICD09
- 755.63 Other congenital deformity of hip (joint)
ICD10
- Q65.89 Other specified congenital deformities of hip
SNOMED
- 52781008 congenital hip dysplasia (disorder)
FAQ
- Q: Are screening protocols unified?
- A: Screening and treatment protocols can vary, but the principles are the same. The earlier screening protocol is adopted from the American Academy of Pediatrics Clinical Practice Guideline and Johns Hopkins Pediatric Orthopaedics.
- Q: Why are ultrasound and radiographs used at different age ranges?
- A: After about 3 months of age, radiographs become easier to assess, as radiographs require ossification and ultrasound waves cannot penetrate ossified bone. The hip is not fully ossified at birth, rendering early radiographic examination difficult.
- Q: Why are the Barlow/Ortolani exams used before 3 months of age but not as useful later?
- A: These exams become less useful as the hip naturally stiffens after 3 months, as stiffness results in asymmetric motion but not instability.