Perthe’ s disease or Legg-Calve- Perthe’s disease
*Was described in 1910 , independently by 3 different people.*It is painful disorder of the childhood characterized by avascular necrosis of the femoral head.
*It is uncommon in any community , about 1 in 10,000 with a higher incidence in Japanese , and central Europeans and a lower incidence in native Americans
*patients are usually 4- 10 years old.
*boys are affected 4 times as often as girls.
pathogenesis
*The exact cause of Perthe’s disease is unknown , but the cardinal step in the pathogenesis is ischemia of the femoral head.
*Up to the age of 4 months , the femoral head is supplied by :
1- metaphyseal vessels which penetrate the growth plate.
2- lateral epiphyseal vessels running in the retinacula.
3– scanty vessels in the ligamentum teres.
*the metaphyseal supply gradually declines until by the age of 4 years , it has virtually disappeared.
*by the age of 7 years , the vessels in the ligamentum teres have developed.
*between 4 and 7 years of age , the femoral head may depend for its blood supply and venous drainage almost entirely on the lateral epiphyseal vessels whose situation in the retinacula makes them susceptible to stretching and to pressure from an effusion.
*although such pressure may be insufficient to block off the arterial flow , it could easily cause venous stasis resulting in arise in intraosseous pressure and consequent ischemia.
*the immediate cause of capsular tamponade may be an effusion following trauma ( of which there is a history in over half the cases ). or a non- specific synovitis.
pathology
*the pathological process goes through several stages which in total may last up to 3 or 4 years.
Stage 1 : ischemia and bone death
- all or part of the bony nucleus of the femoral head is dead.
- it still looks normal on plain x- ray.
-the cartilaginous part of the femoral head , being nourished by synovial fluid , remains viable and becomes thicker.
Stage 2 : revascularization and repair
- within weeks or even days of infarction a number of changes begin to appear.
- the bone is revascularized and new lamellae are laid down on the dead trabeculae , producing the appearance of increased density on x- ray.
- some of the dead trabecular fragments are resorbed and replaced by fibrous tissue.The alternating areas of sclerosis and fibrosis appear on the x- ray as fragmentation of the epiphysis.
Stage 3 : Distortion and remodeling :
- if the repair process is rapid and complete , the bony architecture may be restored before the femoral head loses its shape.
- if it is tardy , the bony epiphysis may collapse and subsequent growth of the femoral head and neck will be distorted .
- the head becomes oval or flattened like the head of a mushroom , and enlarged laterally, and the neck is often short and broad.
Clinical features
*the patient typically a boy of 4- 10 years complains of pain and starts limping.
*symptoms may recur intermittently.
*in 4 % of cases , there is an associated urogenital anomaly.
**Early on , the joint is irritable so that all movements are diminished and their extremes painful.
**Often the child is not seen till later , when most movements are full , but abduction ( especially in flexion ) , is nearly always limited and usually internal rotation also.
Plain x – ray
**at first the x – ray may be normal .
**the classic feature of increased density of the ossific nucleus occurs somewhat later. ( necrotic phase ).
*note : the radiographically dense areas are due to the new bone formation that always follows bone necrosis.
**then there will be ( fragmentation phase ) , in which there are alternating patches of density and lucency .
** With ( healing phase ) , the femoral head may regain its normal or near normal shape , or it becomes mushroom- shaped, larger than normal and laterally displaced in a dysplastic accetabular socket.
Prognostic features
1- age : is most important prognostic factor .
- in children under 6 years the outcome is almost always excellent.
- the older the child , the less good is the prognosis.
2- sex : girls have poorer prognosis than boys.
3- the degree of femoral head involvement : the greater the degree , the worse the outcome.
4- the head at risk radiographic signs
A- progressive uncovering of the epiphysis.
B- calcification of the cartilage lateral to the ossific nucleus.
C- a radiolucent area at the lateral edge of bony epiphysis ( Gage’s sign ) .
D- severe metaphyseal resorption.
Treatment
- At stage of joint irritability :
- analgesia and modification of activities are often sufficient , but hospitalization for bed rest and short periods of traction are sometimes necessary.
- wheelchair use and crutch walking should be discouraged in order to avoid unnecessary joint stiffness and contracture.
Once joint irritability has subsided : which usually takes about 3 weeks , movement is encouraged .
*The further treatment may include
1- symptomatic treatment : means pain control ( if necessary by further spells of traction ) , gentle exercise to maintain movement and regular reassessment.
2-containment : means taking active steps to seat the femoral head congruently and as fully as possible in the acetabular socket , so that it may retain its sphericality and not become displaced during the period of healing and remodeling.
This is achieved by either holding the hips widely abducted in plaster or removable brace or by operation.
Operations include either varus osteotomy of the femur or an innominate osteotomy of the pelvis or both.
Slipped capital femoral epiphysis
*Also called femoral capital epiphysiolysis
Displacement of the proximal femoral epiphysis ( SCFE ) uncommon 1-3 per 100 000 .
It is confined to children going through the pubertal growth spurt.
Boys are affected more than girls.
Left hip is affected more commonly than the right.
If one hip slips , there is a 25 – 40 % risk of the other side also slipping.
Many of the patients are either fat and sexually immature or excessively tall and thin.
*Aetiology :
1- hormonal imbalance theory :
- normally , pituitary hormone activity , which stimulates rapid growth and increased physeal hypertrophy during puberty , is balanced by increasing gonadal hormone activity , which promotes physeal maturation and epiphyseal fusion.
A disparity between these two processes may result in the physis being unable to resist the shearing stresses imposed by the increase in body weight.
- Oestrogens produce a decrease in physeal width and increased physeal strength , which may partly explain the lower incidence in girls and rare occurrence after menarche.
2- the perichondrial ring ( the retaining collar around the physis ) is relatively thinned in this age group and provides less support for the increased load transmitted through the physis during the growth spurt.
3- trauma : plays a part , especially in the 30 % of the cases with an acute slip.
-in the other 70 % , there is a slow progressive displacement or a series of slight displacements , chronic slip .
- Sometimes , acute on chronic slip can occur.
Pathology
In slipped epiphysis the femoral shaft rolls into external rotation and the femoral neck is displaced forwards while the epiphysis remains seated in the acetabulum.
Disruption occurs through the hypertrophic zone of the physis.
Relatively speaking , the epiphysis slips posteriorly on the femoral neck.
If the slip is severe , the anterior retinacular vessels are torn.
At the back of the femoral neck the periosteum is lifted from the bone with the vessels intact , this may be the main or the only source of blood supply to femoral head. And if damaged by manipulation or operation then avascular necrosis of the head may result.
Clinical features :
Slipping usually occurs as a series of minor episodes rather than a sudden acute event.
The patient is usually a child around puberty , typically overweight or very tall and thin.
The presenting symptom is almost pain , sometimes in the groin , BUT often only in the thigh or knee which can be very misleading.
The pain soon disappears only to recur with further exercise.
Limping also occurs early.
On examination the leg is externally rotated and is 1-2 cm short , there is limitation of flexion , abduction and medial rotation.
A classic sign is the tendency to increasing external rotation as the hip flexed.
Following an acute slip , the hip is irritable and all movements are accompanied by pain.
Imaging :
**X – ray
In very early cases the x - ray may be reported as normal.
Then there will be - decreased in the epiphyseal height.
- physeal widening.
- lesser trochanter prominence due to
- increases external rotation of the femur.
In AP view a line drawn along the superior surface of the femoral neck should normally intersect the epiphysis.In an early slip the epiphysis may be flush with or even below this line ( Trethowan s sign ).
In LATERAL view measure the angle subtended by the epiphyseal base and the femoral neck. This is normally a right angle and anything less than 87 degrees means the epiphysis is tilted posteriorly.
**MRI : has been used to detect the stage of avascular necrosis of the femoral head.
-**CT scan : 3 D CT scan can be used in the preoperative planning of realignment procedures for complex proximal femoral deformities.
** Ultrasonography : may detect a hip effusion associated with an acute event.
Treatment
The aim of treatment are :
1- to preserve the epiphyseal blood supply.
2- to stabilize the physis.
3- to correct any residual deformity.
-manipulative reduction of the slip carries a high risk of avascular necrosis and should be avoided.
-The choice of treatment depends on the degree of slip :
1-Minor slip :
- Less than one third of the epiphysis on AP x –ray and less than 20 degrees tilt in the LATERAL view.
-deformity is minimal and needs no correction.
-the position is accepted and the physis is stabilized by inserting one or two screws or threaded pins along the femoral neck and into the epiphysis , under fluoroscopic control.
2-Moderate slip :
Between one third and two thirds of the width of the epiphysis on the AP x- ray and 20 – 40 degrees of the tilt in the lateral view.
Deformity here is usually tempered by gradual bone modeling and may in the end cause little disability.
So we can accept the position , fix the epiphysis in situ and then wait .
If after a year or two , there is a noticeable deformity , a corrective osteotomy is performed below the femoral neck.
3- severe slip :
More than two thirds of the width of the epiphysis on the AP x- ray and 40 degrees of tilt in the lateral view.
This is unacceptable slip and causes marked deformity and if untreated , it will predispose to secondary OA.
Closed reduction by manipulation is dangerous and should not be attempted.
Open reduction by Dunn s method gives good results.
Alternative method is to fix the epiphysis as for a moderate slip and then as soon as fusion is complete , to perform a compensatory intertrochanteric osteotomy.
Complications
1- Slipping at the opposite hip
25 % - 40% of cases slipping occurs at the other hip.
2- Avascular necrosis of the femoral head.
3- Articular chondrolysis .
4- Coxa vara.