Background

 

 

Definition

 

Developmental dysplasia of the hip

- the femoral head does not have the normal relationship with the acetabulum

- the acetabulum is dependent on the femoral head for normal development

 

Four clinical patterns

 

Hip instability	Acetabular dysplasia	Subluxed hip	Dislocated hip
Looseness / laxity	Normal relationship of the hip Acetabulum shallower and more vertical	Non concentric contact between femoral head and acetabulum   Reducible or irreducible	No contact between femoral head and acetabulum   Reducible or irreducible

 

Epidemiology

 

Hip instability 1%

- 5/1000 males

- 13/1000 females

- 90% resolve spontaneously

 

Unilateral 63% / left side 64%

 

75% of patients with DDH are female

 

Etiology

 

Tirta et al JAMA Netw Open 2025

- meta-analysis for risk factors of 64,000 DDH

- breech delivery / family history DDH / oligohydraminos / female

 

Ligamentous laxity	Mechanical theory	Familial	Associated disorders
Females   Progresterone rich environment   Familial hyperlaxity / collagen disorders	Breech / Twins    First born   High birth weight   Oligohydraminos   Swaddling	12x increased risk with sister / daughter	Larsen's / Arthrogryposis   Torticollis   Meta-tarsus adductus   Congenital knee dislocation

 

Pathology

 

Acetabular dysplasia	Femoral head	Capsule	Soft tissue
Becomes vertical and shallow   Neolimbus - crest of new fibrocartilage - between true and false acetabulum	Dislocates superior and posterior   Head deformed   Neck short and anteverted	Capsule enlarged / stretched   Zona orbicularis - capsule narrows where iliopsoas crosses	Labrum thickened +/- inverted (limbus)   Ligamentum teres thicker   Pulvinar thickened    Transverse ligament pulled superior and forms blockage

 

Natural history

 

Acetabular dysplasia - associated with early development of osteoarthritis (OA)

 

Hip subluxation - leads to OA in 30's and 40's 

 

Hip dislocation

- articulates with ilium: very early OA

- no articulation with ilium: pain free but abnormal gait (bilateral waddling gait, unilateral short leg gait) until 40s

 

Screening

 

Clinical examination of the hips in all newborns

 

Any abnormal findings or high risk - ultrasound

 

Selective ultrasound screening

 

Indications

- positive clinical findings

- breech/ oligohydraminos / multiple births / family history DDH

- foot deformities (CTEV / metatarsus adductus), torticollis

 

Universal ultrasound screening

 

Issue - 90% unstable hips will resolve without treatment

 

Cheok et al Bone Joint J 2023

- systematic review of universal v selective screening

- overall incidence late presenting DDH is 1/10,000

- universal screening reduced late presenting DDH

- universal screening increased incidence abduction bracing without reducing incidence later surgery

 

Examination neonate

 

 

Asymmetric thigh folds / creases

 

Reduced abduction - normal abduction is 80 - 90°

 

Dynamic maneuvers

 

Hip is stable / subluxable / dislocated and reducible / dislocated and non-reducible 

 

Ortolani test	Barlow provocation test
Hip is Out, Ortolani test reduces hip	Push hip Back out with adduction and posterior force
Thumb on adductor tubercle & ring finger on GT - hip and knee 90° flexion - abduct hip & lift GT forward - clunk of reduction felt	One hand holds pelvis - adduction to 10o while axial pushing thigh backward - dislocates in this position over posterior acetabulum - feel clunk of dislocation - may feel sliding of subluxing hip

 

Ortolani test: the hip is dislocated with the leg adducted

 

               

Ortolani test: feel the hip reduce with abduction

 

Barlow test: feel the hip sublux or dislocated with the hip adducted and a posterior force

 

Chavoshi et al Arch Bone Jt Surg 2022

- systematic review of examination findings in neonatal DDH 

- sensitivity 37%, specificity 98%

 

Ultrasound

 

Background

 

Best imaging before 4 - 6 months when superior femoral epiphysis cartilaginous

 

Chavoshi et al Arch Bone Jt Surg

- systematic review of accuracy of ultrasound in DDH

- sensitivity 93%, specificity 97%

 

 

Alpha Angle	Beta Angle	Dynamic
Between ilium & bony roof acetabulum	Between ilium & cartilage roof / labrum	Ultrasound Ortolani / Barlow
Normal > 60°   The lower the alpha angle, the more subluxed the hip is	Normal < 60o

 

Alpha angle between ilium and bony roof of acetabulum

 

Beta angle between ilium and cartilage roof / labrum

 

Dislocated hip on ultrasound

 

Dislocated hip on ultrasound

 

Graf Classification

 

	Alpha angle	Beta angle	Findings
Type I	> 60	< 55	Normal
Type II	43 - 60	55 - 77	Delayed ossification SFE
Type III	< 43	> 77	Subluxed
Type IV	Unmeasurable	Unmeasurable	Dislocated

 

 AP X-ray

 

Timing

 

AP after 6 months of age when the superior femoral epiphysis becomes ossified

 

Create 4 quadrants on xray

- Hilgenreiner's Line - horizontal through triradiate cartilages

- Perkin's Line - vertical through lateral edge of bony acetabulum

- superior femoral epiphysis (SFE) should be in inner and lower quadrant

 

Dislocated hip with smaller superior femoral epiphysis (SFE) and location in the upper outer quadrant

 

Findings

 

Superior femoral epiphysis	Disrupted Shenton's line	Increased acetabular index	Increased head to teardrop distance
Smaller   In upper/ outer quadrant	Line along inferior neck   Line inferior border superior ramus	Angle between Hilgenreiner's line and acetabular line	Lateral tear drop to medial ossification center
		Normal < 30° DDH > 35°

 

 

Von Rosen's view

 

Technique

 

AP pelvis with legs abducted 45° & IR 20°

Lines along femoral shafts should pass through center acetabulum & intersect at sacrum

 

 

Management 

 

Principles

 

1.  The older the age of treatment, the worse the outcomes

2.  Acetabular potential for correction diminishes significantly after the age of 3 - 4 

3.  Aim to achieve a stable concentric reduction of the femoral head into the acetabulum without AVN

4.  To correct acetabular dysplasia

 

Guidelines

 

0- 6 months:                Splint

6 - 18 months:             Closed +/- open reduction

18 months - 8:             Open reduction + acetabular osteotomy +/- femoral osteotomy

 

Avascular necrosis

 

AVN of the femoral head on the right

 

Etiology

 

Always iatrogenic / the result of treatment

- doesn't occur in untreated DDH

- excessive abduction in splint or spica

- forceful closed reduction

- vascular damage during medial approach

- failure to adequately detension hip during open reduction (releases, femoral shortening osteotomy

 

Kalamachi and McEwan X-ray classification

 

Type 1	Type 2	Type 3	Type 4
Nucleus only Irregular fragmentation	Lateral physis	Central physis	Whole physis
Head will be normal	Early lateral fusion Femoral head neck short Valgus	Femoral neck short / coxa breva Greater trochanter overgrowth Coxa vara	Coxa breva Coxa vara

 

Clinical outcome

 

Coxa breva / Coxa valga / Coxa vara

LLD

Trendelenberg gait