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Congenital Dislocation of the Hip (CDH) / Developmental Dysplasia of the Hip (DDH)

Note on Terminology: The older term "Congenital Dislocation of the Hip (CDH)" has largely been replaced by Developmental Dysplasia of the Hip (DDH), as the condition represents a spectrum — not just a fixed congenital dislocation — and may develop or worsen postnatally.

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1. Definition & Spectrum

• Dysplasia — shallow acetabulum, femoral head in joint but unstable
• Subluxation — partial loss of contact between femoral head and acetabulum
• Dislocation — complete loss of contact (irreducible = Ortolani negative)
• Dislocatable (Barlow positive) — hip is reduced at rest but can be dislocated with provocation

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2. Epidemiology

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3. Etiology & Risk Factors

Primary Causes:

• Genetic/Familial — positive family history (12× increased risk)
• Ligamentous laxity — maternal relaxin/estrogen crosses placenta, more pronounced in female fetuses
• Acetabular dysplasia — shallow acetabulum fails to adequately cover femoral head

Risk Factors (Mechanical/Positional):

• Breech presentation — most important mechanical risk (10× increased risk)
• First-born child — uterine wall tighter, less amniotic fluid space
• Oligohydramnios
• Swaddling with extended hips (e.g., traditional Navajo or Kazakh swaddling with legs extended)
• Associated conditions: torticollis, clubfoot, metatarsus adductus (other "packaging" defects)

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4. Pathological Anatomy

Changes in the Acetabulum:

• Shallow, steeply inclined (increased acetabular index)
• Filled with fibrofatty tissue (pulvinar)
• Limbus (labrum) may be inverted, blocking reduction

Changes in the Femoral Head:

• Small, hypoplastic, delayed ossification
• Coxa valga (increased neck-shaft angle)
• Excessive anteversion of femoral neck

Changes in Soft Tissues:

• Capsule becomes elongated and hourglass-shaped
• Iliopsoas tendon crosses the capsular neck, obstructing reduction
• Short adductors
• Tight contracted ligamentum teres (elongated)

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5. Classification

Graf Classification (Ultrasound — Infants <6 months)

Tönnis Classification (X-ray)

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6. Clinical Features by Age

Newborn / Neonate (0–3 months)

• Ortolani Test ✅ (Reduction test)
  • Baby supine, hips flexed 90°, abduct hip — "clunk" felt as dislocated head reduces back in
  • Positive = dislocated hip that CAN be reduced
• Barlow Test ✅ (Provocation test)
  • Adduct and posteriorly press hip — "clunk" felt as head dislocates out
  • Positive = located hip that CAN be dislocated

⚠️ Both tests lose sensitivity after 3 months as soft tissues tighten

Infant (3–18 months)

• Limited hip abduction (<60°) on the affected side — most reliable sign
• Galeazzi sign (Allis sign) — knee on affected side appears lower when hips and knees flexed (femoral shortening)
• Asymmetric skin folds (less reliable)
• Leg length discrepancy

Toddler (Walking age, 1–3 years)

• Trendelenburg gait — trunk lurches to affected side (weak abductors)
• Trendelenburg sign positive — pelvis drops on opposite side when standing on affected leg
• Short limb + waddling gait (bilateral DDH → classic "duck waddle")
• Lumbar lordosis (bilateral)

Older Child / Adult (Late presentation)

• Exercise-induced groin/hip pain
• Early osteoarthritis
• Limp

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7. Investigations

Ultrasound (Gold standard <4–6 months)

• Hip not ossified at birth — ultrasound is the imaging of choice
• Measures α angle (acetabular bony roof) — normal ≥60°
• Measures β angle (cartilaginous roof)
• Dynamic assessment of hip stability

Plain X-ray (>4–6 months)

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MRI / CT

• Used pre/post-operatively
• MRI: best for cartilaginous structures, confirms reduction in spica cast
• CT: for osseous anatomy planning before osteotomy

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8. Treatment

0–6 Months: Pavlik Harness

• First-line treatment
• Keeps hips flexed 100–110° and abducted (human position)
• Worn 23 hours/day; success rate ~85–95%
• Contraindicated in teratologic dislocation or older children
• Complication: avascular necrosis (AVN) of femoral head if over-abducted

6–18 Months: Closed Reduction + Hip Spica Cast

• Done under general anesthesia
• Arthrogram performed to confirm reduction
• Hip held in "safe zone" (human position)
• Spica cast for 3–6 months, changed under anesthesia
• Preceded by traction (2 weeks) to relax soft tissues and reduce AVN risk

18 Months – 4 Years: Open Reduction ± Osteotomy

• Open reduction via anterior (Smith-Petersen) approach
• Obstacles to reduction removed: hourglass capsule, inverted limbus, iliopsoas tendon, pulvinar
• Femoral osteotomy: derotation + shortening (reduces tension on femoral head)
• Pelvic osteotomy (Salter, Pemberton, or Dega): redirects acetabulum to cover femoral head

>4 Years: Salvage Procedures

• Shelf operations, Chiari osteotomy
• Total hip replacement in adulthood for failed cases

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9. Complications

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10. Screening

• Neonatal clinical screening (Ortolani + Barlow) — all newborns
• Universal ultrasound at 4–6 weeks in countries like Germany/Austria
• Selective ultrasound in high-risk groups (breech, family history, clinical abnormality) — recommended in the UK and USA
• AAP/AAOS guidelines recommend risk-stratified screening

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11. Key Differentials

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12. Key Exam Points for Class Discussion

• DDH is a spectrum, not just dislocation
• Female, firstborn, breech, family history = classic risk profile
• Ortolani = reduces; Barlow = dislocates (remember: O = Out → back in; B = Barlow boots it out)
• Ultrasound is gold standard in infants; X-ray after ossification
• Pavlik harness = <6 months; Open reduction + osteotomy = >18 months
• AVN of femoral head is the most dreaded complication
• Missed DDH → Trendelenburg gait → early OA

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CDH / DDH — Paediatric Surgery Committee Discussion

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1. The Surgical Objective (Core Principle)

"The objective is to obtain a stable, congruous reduction of the femoral head within the acetabulum while avoiding damage to the capital epiphysis (Avascular Necrosis), which causes stiffness and proximal femoral deformity." — Bailey & Love's Surgery, 28th Ed., p. 638

• Under-treatment → persistent dislocation → early osteoarthritis
• Over-treatment / forceful reduction → AVN → femoral head destruction

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2. Surgical Decision Framework by Age

Age at Diagnosis
     │
     ├── 0–6 months ──────────────► Pavlik Harness (Non-operative)
     │
     ├── 6–18 months ─────────────► Closed Reduction + Spica Cast
     │                               (± Preliminary Traction)
     │
     ├── 18 months – 4 years ─────► Open Reduction ± Femoral Osteotomy
     │                               ± Pelvic Osteotomy
     │
     └── >4 years ────────────────► Open Reduction + Combined Osteotomies
                                     (Salvage procedures in adults)

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3. Non-Operative Management (Surgical Awareness Required)

Pavlik Harness (0–6 months)

• Age >6 months
• Teratologic dislocation (arthrogryposis, myelomeningocele)
• Failure of reduction after 3–4 weeks trial

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4. Closed Reduction Under Anaesthesia (6–18 months)

Pre-operative: Skin or Skeletal Traction (1–3 weeks)

• Gradually stretches soft tissues (iliopsoas, adductors, capsule)
• Brings femoral head down to level of acetabulum
• Reduces the risk of AVN post-reduction
• Some centres have moved away from routine traction; still used selectively

The Procedure:

1. General anaesthesia
2. Arthrogram — contrast injected into hip joint; confirms position of femoral head, identifies obstacles (inverted labrum = "rose thorn" sign, hourglass capsule)
3. Adductor tenotomy — if abduction <45°; performed percutaneously or open to widen safe zone
4. Gentle reduction manoeuvre (Ortolani manoeuvre)
5. Assess safe zone (Ramsey's zone) — arc between:
   • Position where hip redislocates (lateral)
   • Position where AVN risk begins (extreme abduction, medially)
   • Safe zone must be ≥20–30° wide for closed reduction to be acceptable
6. Apply hip spica cast in safe position (typically 45–60° abduction, 90–100° flexion, neutral rotation)

Post-operative:

• MRI or CT to confirm concentric reduction (X-ray unreliable in infants)
• Spica cast changed every 6–8 weeks under GA
• Total casting: 3–6 months
• Followed by Pavlik/abduction brace for further remodeling

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5. Open Reduction (18 months and above)

• Closed reduction fails or safe zone inadequate
• Age >18 months (soft tissue obstacles unlikely to resolve)
• Late-presenting cases
• Teratologic dislocations

Obstacles to Reduction (Surgical Anatomy)

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Surgical Approaches

A. Medial Approach (Ludloff) — 6 to 24 months

• Between adductor longus and pectineus (or gracilis)
• Excellent access to medial obstacles (pulvinar, ligamentum teres, capsule)
• Cannot perform capsulorrhaphy
• Cannot perform pelvic osteotomy simultaneously
• Used for straightforward open reductions in younger infants

B. Anterior (Anterolateral / Smith-Petersen) Approach — >9–12 months

• Between tensor fascia lata (sup. gluteal nerve) and sartorius/rectus femoris (femoral nerve)
• Preferred for older children
• Allows:
  • Complete visualization and removal of all obstacles
  • Capsulorrhaphy (tightening of redundant capsule — critical for stability)
  • Simultaneous pelvic osteotomy
• Internervous plane: TFL (sup. gluteal n.) / Sartorius (femoral n.)

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6. Femoral Osteotomy

Indications:

• Excessive anteversion (>40°) causing instability
• Coxa valga (neck-shaft angle >150°)
• Needed to shorten femur (in late cases — reduces pressure on femoral head, lowers AVN risk)

Types:

• Performed at the subtrochanteric or intertrochanteric level
• Fixed with a blade plate, DCP, or pediatric hip screw
• Often combined with pelvic osteotomy (triple procedure)

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7. Pelvic Osteotomies

Salter Innominate Osteotomy (most commonly discussed)

• Age: 18 months – 6 years (open triradiate cartilage required)
• Mechanism: Single cut through ilium above acetabulum; acetabulum rotated anterolaterally as a unit; bone graft (from iliac crest) holds correction
• Corrects: Anterior and lateral deficiency of coverage
• Limitation: Cannot increase overall acetabular volume

Pemberton Osteotomy

• Incomplete (hinge) osteotomy through ilium curving to triradiate cartilage
• Bends acetabular roof downward — reduces acetabular volume (good for large femoral head coverage)
• Requires open triradiate cartilage as a hinge

Dega Osteotomy

• Similar to Pemberton but hinge is more posterior
• Popular in neuromuscular hip dysplasia (cerebral palsy)
• Good posterior coverage

Triple Pelvic Osteotomy (Steel/Tönnis) — older children with closed triradiate

• Cuts through ilium, ischium, and pubis
• Full mobilization of acetabular fragment
• Used when triradiate cartilage closed (>8 years)

Chiari Osteotomy — salvage

• Medial displacement of ilium above hip joint
• Does not redirect acetabulum; creates a shelf of ilium for coverage
• Used when redirectional osteotomies not possible (older, deformed acetabulum)

Comparison Summary:

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8. The Combined / Triple Procedure

Open Reduction (anterior approach)
        +
Femoral Osteotomy (derotation + varus + shortening)
        +
Pelvic Osteotomy (Salter or Pemberton)

• Minimise number of GA exposures in children
• Allow simultaneous correction of all deformities
• Improve overall surgical outcome

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9. Post-operative Protocol (Surgical)

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10. Complications — Surgical Perspective

Avascular Necrosis (AVN) of Femoral Head — Most Critical

• Caused by: forceful reduction, extreme abduction, surgical insult to blood supply
• Blood supply to femoral head: medial circumflex femoral artery (main) → retinacular vessels
• Kalamchi & MacEwen Classification:

Other Surgical Complications:

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11. Surgical Outcomes — Prognostic Factors

Key prognostic milestone: If the acetabular index normalises to <25° by age 2, the outcome is likely excellent with no further intervention required.

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12. Key Surgical Discussion Points for the Committee

1. Why do we prefer anterior over medial approach in children >12 months? → Allows capsulorrhaphy + simultaneous pelvic osteotomy in one sitting
2. What is the "safe zone" and why does it matter intraoperatively? → Determines feasibility of closed reduction; narrow safe zone = proceed to open
3. Why is femoral shortening osteotomy critical in late-presenting cases? → Reduces lever arm tension on femoral head → prevents AVN
4. What is Pavlik disease and how do we avoid it? → Abandon harness if no reduction in 3–4 weeks; posterior acetabular erosion
5. When do you choose Pemberton over Salter? → Pemberton when femoral head is large relative to acetabulum and you need to reduce volume, not just redirect
6. What is the single most feared complication and why? → AVN — irreversible, leads to femoral head collapse and lifetime disability

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🦴 CDH / DDH — Quick Class Reference

Congenital Dislocation of the Hip | Paediatric Surgery

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📌 DEFINITION

DDH is a spectrum of hip instability — from a mildly shallow socket to a completely dislocated hip that cannot be put back in place.

• Dysplasia → shallow socket, head still inside
• Subluxation → head partially out
• Dislocation → head completely out
• Dislocatable → head in, but can be pushed out

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📌 REMEMBER: WHO GETS IT?

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📌 PATHOLOGY — WHAT CHANGES INSIDE?

🔴 The Socket (Acetabulum)

• Becomes shallow and steep (can't hold the head)
• Fills with fatty tissue (pulvinar) — blocks reduction
• Labrum (limbus) gets inverted — another block to reduction

🟡 The Femoral Head

• Small and underdeveloped
• Femoral neck too angulated (coxa valga)
• Too much twist (anteversion) — head points wrong way

🟢 Soft Tissues

• Capsule stretches and becomes hourglass-shaped — strangles joint
• Iliopsoas tendon tightens across the front — blocks reduction
• Adductor muscles tighten — limit abduction
• Ligamentum teres becomes elongated and loose

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📌 SIGNS & SYMPTOMS — BY AGE

👶 Newborn (0–3 months)

⚠️ Both tests lose value after 3 months — soft tissues tighten and the clunk disappears

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🧒 Infant (3–18 months)

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🚶 Toddler / Walking Child (>1 year)

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🧑 Older Child / Adolescent

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📌 INVESTIGATIONS

Ultrasound — Graf Classification

X-ray — Key Lines to Know

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📌 TREATMENT — AGE BY AGE

🟢 0–6 Months → Pavlik Harness

• Soft harness, keeps hips flexed + slightly apart
• Worn 23 hours/day
• Success ~85–95%
• Stop if no reduction in 3–4 weeks → risk of Pavlik disease

🟡 6–18 Months → Closed Reduction + Spica Cast

• Done under general anaesthesia
• Arthrogram (contrast dye) confirms femoral head position
• Adductor tenotomy done if hip won't open enough
• Hip held in safe position in hip spica cast
• Cast changed every 6–8 weeks under GA

🔴 18 Months – 4 Years → Open Reduction ± Osteotomies

• Surgical approach: Anterior (Smith-Petersen)
• Remove all obstacles inside joint (pulvinar, inverted labrum, tight capsule, iliopsoas)
• Tighten loose capsule (capsulorrhaphy)
• Add femoral osteotomy if neck angle or twist is wrong
• Add pelvic osteotomy if socket is still too shallow

🔵 >4 Years → Combined Surgery

• Open reduction + femoral osteotomy + pelvic osteotomy = Triple Procedure in one sitting
• Longer recovery, higher complication risk
• Salvage osteotomies (Chiari) if socket too deformed to redirect

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📌 PELVIC OSTEOTOMIES — QUICK COMPARISON

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📌 COMPLICATIONS

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📌 AVN — WHY IT HAPPENS & HOW TO AVOID IT

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📌 GOLDEN RULES FOR CLASS

1. Earlier = Better — every month of delay = harder surgery + worse outcome
2. Ortolani reduces, Barlow dislocates
3. USG for babies; X-ray for older children
4. Pavlik → Closed reduction → Open reduction → Osteotomies (age ladder)
5. AVN is the enemy — every surgical decision aims to reduce this risk
6. If acetabular index is <25° by age 2 → excellent prognosis

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