Understanding Different Types of Developmental Dysplasia of the Hip (DDH) and Their Classification

High-Yield Executive Summary

• DDH Spectrum: Developmental Dysplasia of the Hip (DDH) encompasses a range from mild acetabular dysplasia to frank dislocation, requiring tailored management based on severity and patient age.
• Key Anatomy & Biomechanics: The acetabulum’s depth and femoral head coverage are critical for hip stability; dysplasia disrupts load distribution, predisposing to early osteoarthritis.
• Classification Systems: The Graf ultrasound classification guides early infant management; the Tönnis and International Hip Dysplasia Institute (IHDI) radiographic classifications direct treatment in older infants and children.
• Management Algorithm: Non-operative treatment (e.g., Pavlik harness) is effective in infants <6 months with reducible hips; surgical intervention is indicated for irreducible or late-presenting hips, with approach dictated by age and hip morphology.
• Surgical Mastery: Open or closed reduction combined with pelvic and/or femoral osteotomies optimizes joint congruency; intraoperative assessment of reduction stability and soft tissue tension is paramount to prevent avascular necrosis (AVN).

Clinical Fundamentals

Relevant Anatomy and Biomechanics

The hip joint is a ball-and-socket synovial joint formed by the femoral head and the acetabulum. The acetabulum’s depth and the labrum provide containment and stability. In DDH, acetabular dysplasia results in insufficient femoral head coverage, altering joint biomechanics and increasing shear forces on the cartilage and labrum. The proximal femur may exhibit increased anteversion and a valgus neck-shaft angle, further destabilizing the joint.

The vascular supply to the femoral head, primarily from the medial femoral circumflex artery, is vulnerable during reduction maneuvers, making surgical technique critical to avoid AVN.

Epidemiology

DDH incidence varies globally, approximately 1-2 per 1000 live births in Western populations, with higher rates in breech presentations, female infants, and family history. Early diagnosis is essential to prevent long-term morbidity.

Classification & Diagnosis

Diagnostic Pearls

• Ultrasound Timing: Perform before 6 weeks to avoid false positives due to physiologic immaturity.
• Radiographic Landmarks: Hilgenreiner’s, Perkin’s, and Shenton’s lines are essential for assessing displacement.
• Pitfall: Delayed ossification of the femoral head can mimic dislocation; correlate clinically and with serial imaging.

The Decision-Making Algorithm

Why Specific Approaches?

• Pavlik Harness: Maintains hip in flexion and abduction, facilitating reduction without compromising blood supply.
• Closed Reduction: Minimally invasive but limited by soft tissue contractures.
• Open Reduction: Direct visualization reduces risk of iatrogenic injury and allows capsulorrhaphy.
• Pelvic Osteotomies: Reorient acetabulum to improve coverage; choice depends on acetabular morphology and patient age.
• Femoral Osteotomies: Correct excessive anteversion or varus deformity to optimize joint mechanics.

Surgical Mastery & Pearls

Conceptual Surgical Steps for Open Reduction and Pelvic Osteotomy

1. Exposure: Anterior Smith-Petersen approach provides access to the hip capsule and acetabulum.
2. Soft Tissue Release: Adductor longus and iliopsoas tenotomy to reduce tension.
3. Capsulotomy: T-shaped incision to visualize femoral head and acetabulum.
4. Reduction: Gentle manipulation to avoid femoral head vascular compromise; confirm concentric reduction fluoroscopically.
5. Pelvic Osteotomy: Salter or Pemberton osteotomy based on acetabular shape; fix with smooth pins or screws.
6. Capsulorrhaphy: Tighten capsule to maintain reduction.
7. Postoperative Immobilization: Spica cast in appropriate position for 6-8 weeks.

Intraoperative Red Flags

• Excessive force during reduction risking AVN.
• Incomplete soft tissue release causing persistent subluxation.
• Overcorrection in osteotomy leading to impingement or instability.
• Failure to confirm concentric reduction fluoroscopically.

Evidence-Based Synthesis

Recent randomized controlled trials and meta-analyses reinforce early harness treatment efficacy in infants under 6 months, with success rates exceeding 90% in Graf II hips. However, controversy persists regarding the management of Graf IIc hips, where watchful waiting versus immediate harness use remains debated.

Surgical literature supports combined pelvic and femoral osteotomies in older children to optimize outcomes, with studies demonstrating improved acetabular indices and reduced re-dislocation rates. The risk of AVN remains the most significant complication, with evidence favoring gentle reduction techniques and staged soft tissue releases to mitigate this risk.

Emerging data suggest that the IHDI classification offers superior interobserver reliability compared to Tönnis, influencing surgical decision-making and standardizing outcome reporting.

Pro-Tip: Surgical Excellence in DDH Management

Mastery in DDH surgery hinges on meticulous preoperative planning integrating classification data with patient age and hip morphology. Intraoperatively, prioritize gentle, stepwise soft tissue releases and confirm reduction stability under fluoroscopy before fixation. Avoid forceful maneuvers that jeopardize femoral head perfusion. Postoperative protocols should balance immobilization with early mobilization to prevent stiffness without compromising reduction. Continuous reassessment of classification systems and emerging evidence will refine your surgical strategy and optimize long-term hip function.

Last Updated on January 26, 2026 by OrthoNet AI