Incidence : l in 1000

Unstable hip 5-20/1000, known as dysplastic, hips not dislocated.

MC in first born females. F:M::7:1

Lt hip >> Rt hip

More common in Breech delivery & oligohydromnios.

Better terminology to be used now is – Developmental Displacement of HIP (DDH).

Theories

1. Mechanical Factors

2. Hormone induced joint laxity; Maternal hormone - relaxin.

3. Primary acetabular dysplasia

4. Genetic factors.

Associates with other packaging disorder –

Metatarsus adductus,

Congenital muscular torticollis,

Talipes calcaneovalgus,

Plagiocephay,

Extension contracture of knee.

Pathogenesis: Excessive capsular laxity and shallow acetabulum are the primary initiating factors. Dysplasia is the root cause of congenital dislocation but not all the dysplastic hips proceed to this outcome.

Pathology:

• Femoralhead - remains anteverted and in valgus position, is pulled proximally and laterallly by hip abductors; becomes misshapen and flattened has delayed ossification of capital epiphysis.

• Hip joint - filled up with fibrofatty tissue known as pulvinar.

• Acetabular labrum - becomes elongated any may infold into the joint (called inverted limbus)

• Acetabulum becomes flattened because it is not stimulated to develop around the femoral head.

• ligamentum teres becomes lengthened, hypertrophied and redundant.

• Transverse acetabular ligament is pulled superiorly with capsule and blocks the lower position of acetabulum.

• Capsule of the hip joint becomes expanded.

• Muscles:-

1. The Pelvi -Femoral goup (addudctors, hamstrings, sartorius Rectus femoris, T.F.L. and pectineus) are the most formidable obstruction to reduction as they are shortened.

2. The pelvi-trochanteric group - psoas, oburatos, quadriceps become stretched and functiionally incompetent. Psoas function to transmit the body weight along with the capsule.

3. The Gluteal group - non functional because the lever arm vector has no stable fulcrum to act.

Obstructions to Reduction:

1. Pericephalic insertion of the capsule

2. The ligamentum Teres

3. The inverted limbus

4. The Pelvi-Femoral muscle

5. Capsular adhesion and transverse acetabular ligament.

Natural history:

• 90% unstable hip stabilises within 9 weeks.

• The maximum remodelling of the acetabulum occures below 18 months of

age.

• Dislocated hips per se does not develop AVN.

• In un-treated cases, a false acetabulum may develop which on undergo secondary osteorthritic changes over the years.

Clinical findings

At birth:

i) Asymmetrical thigh fold and popliteal crease

ii) Broadened perineum

iii) Asymmetry of Inguinal folds – Fold extending posteriorly and laterally beyond

the anal aperature.

iv) Galleazi sign - shortened femur length

v) Extension looseness of hip and knee

vi) Schoemaker’s line below the umbilicus.

vii) Nelaton’s line: Tip of Greater trochanter lies above the same

viii)Ortolani’s test ( o for out - i. e. subluxated/ dislocated)

ix) Barlows test (B – Bahar Lao i.e dislocatable).

3 -12 months: In addition to above

i) Adduction contracture

ii) Positive telescoping

At walking Age, In addition to above

i) Increase lumbar lordosis with prominent gluteal region

ii)  Gluteus –Medius lurch

iii) Out-toeing and short leg

iv) Compensatory genu valgum at the knee.

v) Positive telescoping test

vi) Positive trendlenburg’s test.

Imaging:

USG- Upto 6 months, better than x rays to diagnose subluxatable hip but   sometimes can over-diagnose.

Methods

— Static (graf)

— Dynamic with examiner performing Barlow’s test.

— Simultaneous anterior imaging (Suzuki technique)

Graf’s classification of dislocation hip

(1) Normal hip

(2) Concentrically reduced but immature and delayed in ossification.

(3) Hip is subluxated or has low dislocation.

(4) Hig dislocation with interposing labrum.

X rays.

a) Quadrant of dislocation:

i) Higenreiner’s or y line : Horizontal line through the upper border of radiolucent

triradiate cartilage.

ii) Perkins line - Vertical line through the most lateral ossific margin of the roof of

the acetabulum to transect perpendicularly and through the y line forming the four quadrants

In subluxated hip - the head is lateral to perkin’s line

In dislocated hip - the head is lateal to perkin’s line and superior to hilgenreiner’s

line.

b) Disruption of (break in) shenton’s arc.

c) Delay in the ossification of the teardrop and ‘U’ shaped tear drop.

d) Acetabular index - angle between the hilgenreiner’s line and tangent to the

lateral ossification roof of the acetabulum.normally in newborn 25 - 30°. (more than 40° is suggestive of acetabular dysplasia).

e) Centre Edge angle (CE) Useful in more than 8 yr, it is the angle between the

lateral border of acetabulum & a vertical line through the centre of the femoral head. Normal - 25°.

f) Von Rosens veiw - In a child with suspected C.D.H, an A.P view with a flexion of 45° & maximal internal rotation may show subluxation.

Arthrography -Useful for following:

1. limbus – Rose thorn sign suggestive of an inverted limbus.

2. Hourglass constriction of capsule.

3. Capsular distension.

4. Medial pooling of dye may suggest subluxation.

5. Determining the concentricity of reduction < 7mm medial pooling with

concentric reduction during closed reduction under anaesthesia rules out need of

an open reduction.

CT Scan

— Done after closed reduction & casting to determine the concentricity of reduction.

— prior to performing salter’s innominate osteotomy.for 3D reconstruction and assess extent of femoral torsion.

Treatment

varies according to different age groups

1. Newborn to 6 mnths.

2. 6 months to 18 months.

3. 18 months to 3 years.

4. 3 years to 8 years.

5. Adolescent and young adult.

New born:

• Palvik Harness sucess rate 85% -98%.

• A dynamic flexion- abduction orthosis.

• Contra-indicated in teratological dislocations.

• Likelihood of failure if the superior gap is less than 3mm and medial gap is more

than 10mm ( measured from hilgenreiner’s line and perkin’s line respectively)

• Consists of a chest strap, two shoulder straps and two stirrups.

Infants (6 - 18 months)

• Pre-operative traction, adductor tenotomy.

• Closed reduction under anaesthesia and casting.

• Confirmed by arthrography – acceptable criteria is medial dye pooling of 7mm

or less and maintainence of the reduction in an acceptable safe zone.

• Safe zone concept of Ramsey – The arc between the angle of abduction which

can be comfortably achieved and the angle which allows redislocation.

A wide safe zone i.e minimum of 20 degrees (preferably 45 degree is desirable).

• Arthrogram is done one finger breadth lateral to femoral artery and immediately

inferior to the ASIS by anterior approach.

• Application of hip spica – Kumar technique - human position of 90° flexion,

40°-45° abduction. The most common mistake is overflexion and under abduction.

Open reduction: Done if the efforts  to reduce a dislocation without application of force has failed.

Medial approach of Ferguson & Ludloff

• Capital Epiphysis must be present

• If no capital epiphysis, there is an increased risk of AVN

• 6 month of age is minimum, usually done at 9month.

Advantage:

1. Small groin incision

2. Few soft tissues that are divided – psoas tenotomy, hip capsulatomy, transverse acetabular ligament to lower the risk of A.V.N

Disadvantage

1. Poor exposure

2. Poor visualisation of the interior

3. Unable to reef the redundant capsule.

4. Contra-indicated in unreducible high dislocations, walking child with a false

acetabulum.

Antero-Lateral (Smith Peterson’s Approach)

• Most commonly employed approach

• Can be combined with derotation and femoral shortening.

• Bikini incision along the groin crease – more cosmetic

• Psoas released at the pelvic brim.

• Redundant capsule reefed.

• Do not remove labrum - radial labral incisions made.

• Excise soft tissue interposition i.e Lig. teres.

• Capsulotomy for hour glass constriction.

• Division of transverse acetabular ligament.

Advantage:

1. Excellent exposure

2. T/f of choice in high dislocation

3. Can be combined with femoral surgery.

4. Low risk of A.V.N

Disadvantages:

1. Larger scar

2. Increased blood loss.

Technique:

1. Bilnki incision

2. Lateral femoral cutaneous nerve

retracted medially.

3. Interval between Tensor Fascia Lata and Sartorius is foundl - Ligate ascending

branch of lateral circumflex femoral vessel lying on the Rectus femoris.

4. Illiac crest apophysis is split – elevate abductors.

5. Both head of rectus femoris divided - T incision taken on the capsule.

6. Iliopsoas divided off lesser trochanter

7. Divide transverse acetabular ligament & the bulky ligamentum teres (gives

the landmark to acetabulum which may be filled by fibrofatty ‘pulvinar’.)

8. Reduce the head & double breast the capsule.

9. Femoral shortening & Varus De-Rotation Osteotomy (VDRO) done if required.

Evaluation of the open reduction and deciding further surgery:

1. Hip stable in neutral rotation – No osteotomy.

2. Hip stable in Flexion & Abduction - Innominate osteeotomy

3. Hip stable in Internal rotation & Abduction - VDRO

4. Double diameter acetabulum with antero-lateral deficiency – Pemberton’s

acetabuloplasy. Also if the desired correction is to an extent of >15 degrees, do Pemberton’s. It decreased the volume of acetabulum and does not alter the shape of pelvic cavity ( no problems with child-birth later in life )

Complication of open reduction

— Avascular necrosis of the femoral head

— Bucholz & Ogden classification – to be known

— Management :   i)   Pelvic osteotomy

                              ii)  Trochanteric advancement.

Toddlers: Open reduction and femoral procedure / pelvic osteotomy or both.

Femoral surgery

1. Seperate lateral incision taken

2. Derotation  (external ) upto 60° commonly done with varus (min of 110 degrees, if more correction is needed, do a pelvic procedure).

3. Can be done primarily with open reduction or staged at 6 weeks.

4. Amount of shortening with overlap of bone when hip is reduced and bone osteotomized.

Pelvic Osteotomies

1. Osteotomy of the Innominate bone (Salter’s)

2. Acetabuloplasty (Pemberton’s)

3. Osteotomies to free the acetabulum

(Steel’s;  Triple or Dial’s)

Salvage Procedures

1. Shelf osteotomy (Staheli’s – acetabular augmentation)

2. Innominate osteotomy with medial displacement of the acetabulum (Chiari’s)

Treatment in Juvenile Age group

Open reduction with primary femoral shortening with pelvic osteotomy treatment in olescent and younger adults.

Femoral head cannot be repositioned, only the palliative procedures can be done viz.

1. Subtrochanteric valgus extension osteotomy for pain.

2. Arthrodesis very rarely

3. It painful due to false acetabulum arthritis

— Pelvic osteotomy

— Total hip replacement at an appropriate age – cup placement at the true acetabular region is desired. But risk of Sciatic N palsy – do a wake-up test. Cup placement at false acetabulum is easier but increased risk of early loosening.