Developmental dysplasia of hip

By DR. PRIYESH JAISWAL

Investigation

• Ultrasonography :- Graf pioneered the use of USG for the evaluation of infant hip.

• He proposed classification system on the basis angle formed by sonographic structures of hip.

• He draws 3 lines ;- 1) line passing from ilium that intersect centre of femoral head

• 2) line passing through bony acetabulum, and • 3) line passing through cartilaginous acetabulum

Angle alpha is formed between line 1 & 2

• And angle beta is formed between line 1 & 3.• In DDH , alpha angle decreases and beta angle

increases, depending upon femoral head subluxation.

• Depending upon alpha angle measurment he proposed a classification system

• According to graf class 1 hips are normal ,• Class 2 hips are abnormal or immature type,• Class 3 hips are subluxated and class 4 hips are

dislocated.• He classified class 2 in 3 types:- of which he

noted that class2 c is most important, as it represents preluxation phase .

• USG is also useful in documenting the response of hip to pavlik harness treatment.

Radiograph

• It is not reliable in early stages of DDH but new born screening may reveal severe acetabular dysplasia or teratological dislocation.

• as child grows soft tissue become contracted and radiographs become more helpful in diagnosis.

• Most common used lines of reference are vertical line of Perkins and horizontal line of Hilgenreiner, both used to assess the position of femoral head.

Perkin line is through lateral margin of acetabulum

• While hilgenreiner line is through triradiate cartilage.

• Shenton line is curved line that begins at lesser trochanter, goes upto femoral neck, and connect with line along inner margin of pubis.

• In normal hip, medial beak of femoral metaphysis lies in lower inner quadrant produced by junction of Perkin and hilgenreiner lines.

In dislocated hip , metaphysis lies lateral to the Perkin line and Shenton line is broken.

• Acetabular Index:- is an angle formed by junction of hilgenreiner line and line draw along the acetabular surface.

• In newborn, avg. is 30 degree or less.• Any significant increase in the angle is sign of

acetabular dysplasia.• With increase in age, it is decreased .

Centre –Edge angle

• It is useful to measure hip position.• It is formed at the junction of Perkin line with

line that connects lateral margin of acetabulum to the center of femoral head.

• In children 6-13 yr. old, >19 degree is considered normal.

• In children >=14 yr. old, >25 degree is considered normal.

Von Rosen view

• In this view both hips are Abducted, Internally Rotated and Extended.

• Line is drawn along femoral shaft, which intersect acetabulum.

• In dislocated hip, it crosses above the acetabulum.

Acetabular tear drop

• It is seen in AP radiograph of pelvis.• Formed by several lines ,• Derived from – wall of acetabulum laterally,• Wall of lesser pelvis medially,• Curved line inferiorly and• Acetabular notch.• In normal hip it appears between 6-24 months

of age.

It significans is in the pronosis.

• Hips in which teardrop appears within 6 months of reduction have better outcome than in which it appears late.

• 4 types have been noted:-• Open , closed , crossed and reversed.• Also be describe as U- or V- shaped.• V- shaped associated with poor outcome.

Acetabular index of Depth to Width

• In this depth of central portion of acetabulum is divided by width of acetabular opening.

• Normally >= 38%• Femoral head extrusion index:- • Represents % of femoral head that lies outside

of the acetabulum.

Lateral view of acetabulum[false profile radiograph]

• It is useful for evaluation of anterior acetabular dysplasia.

• Pt. is positioned 65 degree obliquely to the x- ray beam, with foot parallel to the casette.

• Extent of anterior coverage is represented by a dense line of ossification , know as Sourcil.

• Acetabular angle is constructed with mean value of 32.8 degree and range=17.7 -53.6 degree.

Severin classification system of DDH

Arthography

• It is done through median, subadductor approach with image intensification.

• It is important to check for stability of hip after reduction.

• When the hip is placed in reduced position, it may reduce fully against the acetabular wall, or it may dock against the labrum and the capsular constriction of iliopsoas.

When reduction is deep, labrum lies flat over the head and has sharp border.

• When head is docked, labrum is blunted and interposed between the head and acetabular wall.

• Hence , stability of hip joint is confirmed after reduction.

• Arthography can be repeated after 6 weeks to check for head as being well seated in the acetabulum.

MRI

• It gives excellent anatomical visualization of infant hip.

• Kashiwagi and associates proposed classification of hips with DDH.

• Group 1 hips had sharp acetabular rim, all were reducible with Pavlik hareness.

• Group 2 hips had a rounded acetabular rim and almost all are reducible with Pavlik hareness.

Group 3 hips have inverted acetabular rim, and none was reducible with hareness.

• MRI findings includes :- • Widening of iliac bone, • Lateral drift of superior and posterior portions

of acetabular floor, • Overgrowth of acetabular cartilage,• Convexity of posterior portion of cartilage.

MRI with gadolinium- contrast arthography

• Is an important tool for evaluation of adolescent patient with hip dysplasia and pain.

• It allows evalution of labrum and articular cartilage.

• Disruption and tears of the labrum, cartilage delamination, and articular cartilage loss can be identified with this technique.

Screening Criteria

• Infant with below risk factors should undergo screening for hip instability.

• Screening includes clinical examination by experienced examiner and USG of hip.

• Risk factors include :- family h/o DDH , breech birth position, torticollis, metatarsus adductus , and oligohydroamnios .

Treatment

• Is divided in 5 age – related groups• 1) newborn ( birth to 6 months old )• 2) infant ( 6 to 18 months old )• 3) toddler ( 18 to 36 months old )• 4) child ( 3 to 8 yrs. Old )• 5) adolescent and young adult ( > 8 yrs. Old )

Newborn ( birth to 6 months )

• Pavlik harness :- is used in first 6 months , shows excellent result in t/t of DDH.

• It is dynamic flexion-abduction orthosis.• c/I in children who are crawling or fixed soft

tissue contracture, or teratological dislocation present.

• After application, radiograph is taken and confirm the reduction. Hip is placed in flexion of 110 and abduction to occur by gravity itself .

Persistent dislocation of hip

• May be present after application of pavlik hareness , 4 basic pattern is observed

• Superior, inferior , lateral and posterior.• If present following manuvre should be done• Superior – additional flexion is required,• Inferior – flexion should be decreased,• Lateral – closed observation to see for direction

of femoral neck towards triradiate cartilage.

Head may be gradually reduce and dock into the acetabulum.

Persistent posterior dislocation is difficult to treat. As tight hip adductor muscle are present.If any of this persistent dislocation present for more than 3 to 6 weeks, pavlik hareness should be discontinued.t/t includes closed or open reduction and casting.

How long pavlik harness should be continued

• After closed reduction and application of pavlik hareness. Patient is follow up in every 1-2 weeks.

• At this time, hip stability is checked.• Pavlik hareness is discontinued 6 weeks after

clinically hip stability is obtained.• To weaning of up to 2 hrs. per week until

brace is worn at night time.

f/ by night time abduction orthosis for addition month.

• Radiograph and USG(at 3 week interval) examination are useful at 6 month and 1 yr follow up.

• Complications :- femoral nerve palsy ( flexion> 120), + AVN of femoral head = pavlik hareness disease.

• Flattening of posterolateral column of acetabulum.

Other splint

• Ilfeld and von rosen splint have high rate of success with fewer complication but not superior to pavlik hareness.

• Frejka pillow and triple diaper are not used because of high rate of AVN.

Infant ( 6 to 18 month)

• t/t in this age group include :-• Preoperative traction,• Adductor tenotomy,• Closed reduction and arthogram• Open reduction :- if closed reduction fail• Femoral shortening :- in hip with high

proximal dislocation.

Preoperative traction , adductor tenotomy, and gentle reduction with an

• Acceptable safe zone are especially helpful to prevent osteonecrosis of femoral head

Preoperative traction and primary femoral shortening

• Objective is to bring laterally and proximally displaced femoral head down to and below the level of true acetabulum to allow a more gentle reduction.

• Adductor tenotomy :- is performed for mild adductor contracture.

Closed reduction

• A careful clinical evaluation of reduction should be made before and after adductor tenotomy and arthogram performed.

• Closed reduction is performed , sensation of clunk is felt as femoral head reduces in true acetabulum.

• Safe zone concept of Ramsey can be used in determining the zone of abduction and adduction in which femoral head remains reduced in the acetabulum.

Wide safe zone :- abduction of 20 -45 degree is desirable

• Narrow safe zone implies unstable or unacceptable closed reduction.

• Closed reduction is confirmed by performing arthography.

• Criteria for accepting reduction are medial dye pool of 5 mm or less and maintaince of reduction in an acceptable safe zone.

After confirmation of stable reduction hip spica cast is applied.

• Hip is flexion of 95 degree, and 40 -45 degree of abduction.

• Salter advocates this is human position for maintaining hip stability and minimizing the risk of osteonecrosis.

• Kumar describe simple techniques for application of hip spica cast.

Open reduction

• In children, in whom efforts to reduce a dislocation without force have failed, open reduction is indicated to correct the interposed soft tissue structure and to reduce femoral head concentrically in the acetabulum.

• This surgical option is indicated by pathology rather than by age.

Open reduction can be performed by

• Anterior • Anteromedial • Medial approach• Anterior approach :- pathology in the anterior

and lateral aspect of hip can be easily reached and pelvic osteotomy can be easily performed.

Medial approach ;- interval between iliopsoas and pectineus

• Medial circumflex vessel at higher risk.

Concamitant osteotomy

• Zadeh used osteotomy at time of open reduction to maintain stability of reduction.

• 1) Hip stable in neutral position- no osteotomy• 2) Hip stable in flexion and abduction –

innominate osteotomy• 3) Hip stable in internal rotation and

abduction- proximal femoral derotation varus osteotomy.

4) Double diameter acetabulum with anterolateral deficiency

• - Pemberton – type osteotomy.

TERATOLOGICAL DISLOCATIONS

• Is one which occurs at some time before birth, resulting in significant anatomical distortion and resistant to treatment.

• Associated with arthogryposis, Larsen syndrome , myelomeningocele, and diastrophic dwarfism.

• t/t includes open reduction through anterior approach.

• U/L dislocation is treated more aggressively than B/L .

OSTEONECROSIS of femoral head

• Is most serious complication associated with t/t of DDH in this age group.

• It’s sequelae includes – femoral head deformity, acetabular dysplasia, lateral subluxation of femoral head, overgrowth of greater trochanter, and limb length inequalities. OA is late complication

Bucholz and Ogden classification

• For osteonecrosis of femoral head in DDH:-• Based on morphological changes in the capital

femoral epiphysis, physis and proximal femoral metaphysis.

Children with osteonecrosis of femoral head should be followed to maturity with serial radiograph

• Pt. t/t early ( 1- 3 yr.) with innominate osteotomy shows better result .

• Early innominate osteotomy shows to induce spherical remodeling of femoral head, with resultant congruous hip joint.

• Significant overgrowth of G.T., can be t/t with G.T. advancement which increases abductor muscle resting length and increases abductor lever arm.

Children who are 2- 6 yrs. old

• t/t is challenging as femoral head is more proximal in location.

• And muscles around hip joint are more contracted.

• Femoral shortening is essential part of it’s management. In past , child is put on skeletal traction but result of shortening are better and morbidity is less.

In child of age 2-3 yrs old, surgeon should evaluate stability of hip.

• If acetabular coverage is insufficient than pelvic osteotomy should be performed.

• Salter and Pemberton’s osteotomy are most commonly used and are usually succeful.

• Primary femoral shortening + pelvic osteotomy

Primary femoral shortening

Salter innominate osteotomy

• Femoral head is dislocated• Gluteal muscles are retracted and slightly

shortened• Segment of femur is resected• Proximal femur is abducted and iliopsoas

tendon is divided• Capsule is incised on inferior surface parallel

to femoral neck

Salter osteotomy is completed with graft in place

• Osteotomy done in straight line from sciatic notch and AIIS.

• Remove graft from iliac crest and trim into shape of wedge.

• Insert the graft and fixed with K-wire.• Femoral fragments are fixed with pediatric hip

screw.

Pemberton pericapsular osteotomy

• Line of osteotomy beginning slightly superior to AIIS and curving into triradiate cartilage.

• Complete osteotomy with acetabular roof in corrected position and wedge of bone is impacted into open osteotomy site.

• And it is fixed with k- wire .

Steel triple innominate osteotomy

• Ischium, superior pubic ramus and ilium superior to acetabulum all are divided and acetabulum is repositioned and stabilized by bone graft and pins.

Dega osteotomy (transiliac)

• This is incomplete transiliac osteotomy , involves osteotomy of anterior and middle portion of inner cortex of ilium , leaving a intact hinge posteriorly consisting of intact posteromedial iliac cortex and sciatic notch.

• At this osteotomy site , bone graft is placed.

Shelf operation

• It is performed to enlarge volume of the acetabulum.

• Staheli describes slotted acetabular augmentation procedure to crate a congruous acetabular extension in which size and position of augmentation can be easily controlled.

• A deficient acetabulum that cannot be corrected by redirectional pelvic osteotomy is the primary indication.

Before surgery determine C-E Angle of Wiberg from AP standing pelvis radiograph and normal C- E angle of 35

• Measure the additional width necessary to extend the existing acetabulum to achieve the normal angle.

• This determine the width of augmentation, + depth of slot , gives total graft length.

Chiari osteotomy

• Is a capsular interposition arthoplasty.• Indicated when• 1) femoral head cannot be centered adequately

in the acetabulum.• 2) in painful subluxated hips with early sign of

osteoarthritis.• This procedure deepen the acetabulum by medial

displacement of the distal pelvic fragment and improves superolateral femoral coverage.

It places femoral head beneath a surface of cancellous bone with

• Capacity of regeneration and corrects the lateral pathological displacement of femur.

• Osteotomy is performed at the superior margin of acetabulum, and pelvis inferior to osteotomy along with femur is displaced medially.

• Superior fragment of osteotomy then becomes a shelf, and capsule is interposed between it and the femoral head.

It improves biomechanics of the hip by displacing the hip nearer the midline

• Trendelenburg limp often is eliminated.• Chiari’s indications:-• 1) congenital subluxation in pt. 4 -6 yrs. Old

/older• 2)Untreated congenital dislocation . 4 yrs. Old • 3) dysplastic hips with osteoarthritis• 4) paralytic dislocations caused by muscular

weakness or spasticity.

5) Coxa magna after perthes disease or osteonecrosis after t/t of congenital dysplasia.

Adolescent and young adult (> 8 yrs.)

• In these group femoral head cannot be repositioned distally to the level of acetabulum , only salvage procedures are possible.

• After some years , when degenerative changes causes enough pain or limitation of movements, total hip arthoplasty is indicated.

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