Adult Developmental Dysplasia of the Hip (DDH)

1. DEFINITION & OVERVIEW

• Campbell's Operative Orthopaedics 15th Ed 2026
• Miller's Review of Orthopaedics 9th Ed

2. ETIOLOGY & RISK FACTORS

2A. Primary Etiological Factors

2B. Associated Conditions

• Congenital muscular torticollis (8% co-occurrence)
• Metatarsus adductus
• Talipes calcaneovalgus
• Ligamentous hyperlaxity syndromes

2C. Why DDH Persists into Adulthood

3. PATHOLOGY & PATHOANATOMY

3A. Acetabulum

• Shallow socket: acetabulum less than a hemisphere; the "dish" is too flat
• Reduced anterior and lateral coverage of the femoral head
• Increased acetabular index (Tönnis angle) above normal (>10°)
• Reduced lateral center-edge (LCE) angle (<20°)
• Superolateral subluxation of the femoral head with high articular contact stresses concentrated at the superolateral rim
• Broadened radiographic teardrop: the hip center is lateralized

3B. Proximal Femur

• Coxa valga: increased neck-shaft angle
• Increased femoral anteversion: the femoral neck points abnormally forward
• Small, flattened femoral head with a lateral contour deficiency
• Cam morphology (increased alpha angle) co-exists in 10-40% of dysplastic hips and can cause FAI after surgical correction if not addressed

3C. Soft Tissue Changes

• Labral hypertrophy / tear: the labrum compensatorily enlarges to increase functional coverage; it is then subjected to high tensile stress and tears
• Capsular laxity: chronic instability stresses the capsule
• Shortened abductor musculature (gluteus medius/minimus) with altered lever arm
• Psoas tendon contracture

3D. Consequences: Pathological Cascade

1. Labral tear and degeneration
2. Cartilage delamination at the superolateral acetabulum
3. Progressive subchondral damage
4. Osteoarthritis (commonly by age 45-65 if LCE angle <16°)

4. CLASSIFICATION: CROWE SYSTEM

5. SIGNS & SYMPTOMS

5A. Clinical Presentation

• Groin pain with activity - initially only with high-stress activities (running, prolonged standing), later with activities of daily living
• Mechanical symptoms: clicking, catching, giving-way of the hip
• Anterior groin ache - from labral tear and capsular stress

• Constant groin and lateral hip pain
• Limping / Trendelenburg gait: abductor weakness from altered lever arm leads to a positive Trendelenburg sign; in bilateral DDH, a waddling gait
• Leg length discrepancy (affected side shorter in subluxated/dislocated hips)
• Fatigue easily with walking
• Reduced hip range of motion, especially internal rotation and abduction
• Lumbar spine pain: compensatory hyperlordosis and spinal overload

5B. Special Clinical Tests

6. RADIOGRAPHIC MEASUREMENTS (KEY PARAMETERS)

Key Radiographic Parameters for DDH Diagnosis

7. INVESTIGATIONS & EVALUATION

7A. Plain Radiography (First Line)

1. Standing AP pelvis - assess CE angle, acetabular index, Shenton line, Tönnis OA grade, lateralization
2. False profile view (Lequesne) - assess anterior CE angle and anterior coverage
3. AP pelvis with hip in abduction and slight flexion - simulates correction achievable with PAO; tests congruence

• LCE angle <20°
• Tönnis angle >10°
• Lateralized hip center with broadened teardrop
• Disrupted Shenton line
• Elevated Tönnis OA grade
• Coxa valga (increased neck-shaft angle)
• Excessive femoral anteversion (visible on AP)

7B. MR Arthrography (Gold Standard for Cartilage/Labrum)

• Gadolinium intra-articular contrast injection followed by MRI
• Best modality to assess labral tears and cartilage delamination
• Identifies which patients still have adequate joint space for hip-preservation surgery vs. those requiring THA
• Typical findings in adult DDH: posterosuperior labral hypertrophy with tear at the superolateral acetabulum, chondral delamination

7C. Low-Dose CT Scan

• Assess acetabular and femoral version (combined anteversion is key surgical planning data)
• Identify femoral neck morphology and neck-shaft angle
• Plan osteotomy level for shortening procedures (Crowe III/IV)
• A few dedicated slices through the femoral epicondyles allow measurement of femoral anteversion

7D. Ultrasound

• Primary role in neonatal screening (Graf classification), not typically used for adult evaluation
• Can image the labrum and iliopsoas tendon in adults but MR arthrogram is superior

7E. Tönnis Grading of OA (Treatment Guide)

8. TREATMENT

1. Patient's skeletal maturity and age
2. Degree of dysplasia (Crowe grade)
3. Degree of OA (Tönnis grade)
4. Femoral head sphericity and joint congruence
5. Specific anatomic deformity (acetabular vs. femoral vs. combined)

8A. Conservative (Non-Surgical) Management

• Mild dysplasia without significant symptoms
• Patients with severe OA not yet ready for surgery
• Temporary symptom management

• Activity modification: avoid impact activities (running, jumping)
• Physical therapy: hip abductor strengthening, gait training, core stabilization
• NSAIDs for pain
• Intra-articular corticosteroid or hyaluronic acid injections: short-term symptomatic relief; also useful as a diagnostic tool to confirm intra-articular source of pain

8B. Hip Preservation: Periacetabular Osteotomy (PAO) - Bernese PAO

• Tönnis grade 0-1 (or mild grade 2)
• Spherical femoral head with good joint congruence
• Skeletal maturity (typically age 15-45)

• Increase lateral coverage (normalize CE angle)
• Normalize the acetabular index to 0°
• Restore appropriate socket anteversion
• Medialize the center of rotation (reduces joint reactive forces)

• Acetabular index → 0°
• Lateral CE angle → 25-35° (normalize, do NOT overcorrect)
• Avoid retroversion (overcorrection causes secondary FAI)
• Address concomitant cam morphology with femoral osteochondroplasty if needed

• Good-to-excellent long-term results in appropriately selected patients
• Hip joint preservation: 73-76% at >9 years, 60% at 20 years, 29% at 30 years
• Survival is best in Tönnis grade 0 with a spherical, congruent head

• Intertrochanteric varus osteotomy for coxa valga (to address femoral side deformity)
• Femoral osteochondroplasty (for cam FAI)
• Hip arthroscopy (labral repair, chondral debridement)

8C. Hip Arthroscopy

• Isolated labral tears in mild dysplasia without significant structural undercoverage
• Caution: arthroscopy alone in significant dysplasia without addressing the underlying instability can worsen outcomes; it must be carefully selected

8D. Total Hip Arthroplasty (THA)

• Tönnis grade 2-3 (advanced OA)
• Severe dysplasia (Crowe III/IV) with no viable joint preservation
• Older age (typically >50 years, but depends on functional demands)
• Failed previous preservation surgery

9. SURGICAL DECISION ALGORITHM

Adult hip pain with suspected DDH
        ↓
AP pelvis + false profile X-rays
        ↓
CE angle <20°, Tönnis angle >10°?
        ↓
Yes → MR arthrogram + CT (version/anatomy)
        ↓
┌─────────────────────────────────────────────────────┐
│ Tönnis 0-1 + Spherical head + Age <45-50            │
│ → Bernese PAO (+ femoral osteotomy if coxa valga)  │
└─────────────────────────────────────────────────────┘
        ↓
┌─────────────────────────────────────────────────────┐
│ Tönnis 2-3 OR severe OA OR failed PAO OR Age >50   │
│ → Total Hip Arthroplasty (± shortening osteotomy)  │
└─────────────────────────────────────────────────────┘

10. NATURAL HISTORY (UNTREATED)

• Hips with LCE angle <16° routinely develop significant osteoarthritis by age 65
• Progressive labral tear → chondral delamination → joint space loss
• Eventual severe OA requiring THA
• Bilateral DDH leads to characteristic waddle, early disability, and profound quality-of-life impact

11. SUMMARY TABLE

• Campbell's Operative Orthopaedics 15th Ed 2026, Chapters 7 & 32
• Miller's Review of Orthopaedics 9th Ed, Chapter 5
• Bailey and Love's Short Practice of Surgery 28th Ed, Chapter 39
• StatPearls - DDH (2024)
• MDPI - DDH Etiopathogenesis Review