PEDIATRIC PERTH’S DISEASE

Introduction.

Legg-Calvé Perth’s Disease or in another word Avascular necrosis of epiphysis of the proximal femoral head, Osteochondritis coxae juveniles coxa plana is osteochondrosis due to AVN of the capital femoral epiphysis.

Also called idiopathic osteonecrosis of the capital femoral epiphysis, is a famous form of epiphyseal osteonecrosis. Children are often susceptible to the disease due to the improper calcification rate that occurs in the skeletal tissue. It is fundamental to mention that the condition may result in the manifestation of symptoms such as lower limb pain, immobility, and swelling (1).

It is, hence, the role of the radiographer and medical practitioner to ensure the proper management of the disease as a way of reducing future onset complications. there are peculiarities that distinguish Perth disease that happens in skeletons that get growing from avascular necrosis that occurs in the adult femoral head.

LCP is a classic an illustrative example of the clinical course and prognosis related to epiphyseal osteonecrosis at the femoral head (2). This illustration necessitates the need for the utilization of supportive management as an adjunct for treatment of the disease.

Pathophysiology:

Pathology occurs through four distinct stages. The first stage incorporates the process of ischemia which occurs at the femoral caput. Injury or disease may provoke ischemia in the femoral region. Often, trauma may cause the occlusion of the vessels nourishing the region around the femoral caput.

Ischemia abolishes the blood supply running to the femoral caput. The tissue cells lack nutrients for survival. Alternatively, accumulation of metabolic wastes occurs at the region of the affected bone. It is relevant to point out that ischemia precedes the process of osteonecrosis occurring at the femoral caput.

Additionally, the first component of the pathology includes the process of tissue death occurring at the bone region next to the femoral caput. It is relevant to mention that the osteonecrosis activity commences at this region resulting in the advancement of the disease condition (3). The second part of the pathological process involves the resorption and repair of the bone at the affected anatomical region.

It is crucial to mention that the diseased tissue incites a pathological process which results in the resorption of damaged cells. The process of resorption coincides with the fragmentation activity occurring at the skeletal bone of the femur caput. Accordingly, the fragmentation aids the tissue to undergo a new process of vascularization. As mentioned earlier, ischemia usually precedes the entire process of necrosis.

Thus, the activity of re-vascularization usually results in the development of vessels on the repaired tissue. It is worth noting that revascularization coincides with the activity of repair. The bone tissue starts undergoing a process of repair which results in the build-up and formation of new cells and tissues (4).

The bone undergoes a whole reformation and transition activity which leads to the development of repaired bone and tissue after osteonecrosis. The third stage of the pathological process incorporates the entire activity of re-ossification. This stage principally involves the overactivity of osteoblasts and the inhibition of the osteoclasts. Based on this principle, the epiphyseal plate undergoes a major re-ossification process resulting in the formation of a bony prominence around the femoral neck.

This activity may result in the obstruction of the vascular supply at the femoral bony region (5). It is worth mentioning that the fourth stage of the pathological process incorporates the remodeling phase of the femoral bone. At this stage, the femoral head may undergo the process of flattening and collapse. It is thus, critical for the radiographer to make proper adjustments to avoid this complication.

The last stage of LCPD start after the head is fully re-ossified and so remodeling still happening till the child reaches maturity and the disease damage the epiphysis of the head of the femur and cause increase size of the trochanter and shortening of the neck what’s called coxa breva. short neck 6

Incidence and Associations:

Perth disease has a Male and White prominence, it’s the Age of four to eight years that is preferable for that disease. Its bilateral incidence is low (2). and when it occurs bilaterally it’s usually asynchronous (7). The incongruity of joint cause premature degeneration in 2nd or 3rd decades of life (7).

Aetiology:

The main cause of Perth’s disease is the decrease of blood reaching to the epiphysis of the capital and the physics play a role as an avascular barrier Infarction which causes fracture of the trabecula and results in reducing the epiphyseal height (7).

     There is no definite known cause of that avascular necrosis even the genetic proved to not have a direct relation to it. Although few studies have referred to some sort of relation between Perth’s disease and some other disease like ADHD (Attention Deficit Hyperactivity Disorder) and some congenital anomalies like Undescended Testis (8).

Clinical Features and Examinations:

Clinical presentation of the child varies according to his Age, but usually, the child comes with joint pain and Limb that are increased by doing physical activity, on examination, we notice that the abduction is limited abduction as well as the hip internal rotation (9). and referred knee pain which leads to Limb (7). Muscle spasm, thigh & buttocks Atrophy, otherwise the child has no abnormality (2).

Important of Early Diagnosis:

When we talk about the prognosis of this disease. there’s a role (The younger Age is the better Prognosis and the smaller necrosis, the better prognosis) (7).  That’s Why Early Diagnosis is important as Children < 6 years have a good course and prognosis, while children > 8 years have a worse prognosis and may require surgery (10).

 

Differential Diagnosis:

Perth’s Disease is a disease of differential diagnosis, in the following, we are going to the numerate differential diagnosis of Perth’s disease and what characterizes it.

First, we will talk about Septic Arthritis that characterized by acute onset of fever, increase WBCs. We can differentiate it from Perth’s as in septic Arthritis the Hips are held in flexion, abduction, and external rotation, while in Perth’s the hip is adducted. there is also Joint effusion and joint debris and may be marrow edema. (7).

Secondly, we will talk about Juvenile Osteonecrosis, which is Avascular necrosis due to known cause as Sickle cell anemia, steroids, Gaucher, after hip dislocation. (7).

Epiphyseal Dysplasia is another important disease that can be divided into multifocal which have Spondylo-epiphyseal and multiple epiphyseal dysplasia. And Limited to hips in Meyer dysplasia. (7).

Toxic Synovitis is another important disease which is Self-limiting acute synovitis. while steroid Osteoma characterizes by local nigh pain which decreases by NSAID (7).

Investigations: (modalities):

Due to this assertion, radiographers have been at the forefront of the management of Perth’s disease. The principal imaging methods include the utilization of the plain radiograph, MRI, and arthrography as imaging interventions of the disease.

CT scans are good another method critical in the assessment of Perth’s disease, MR is helpful for early changes of acute infarction or revascularization late MR better delineates the extent of involvement (7). in the following part, we will talk about the imaging modalities.

1- Plain Radiograph.

A plain radiograph of the pelvis is the most common procedure involved as part of the diagnosis of the disease condition and the imaging technique of choice among many radiographers.

The radiograph is, moreover, capable of identifying the various stages involved in the disease development of Perth’s disease.

Positions that used to diagnose LCPD involve the following: First Ant-Post position erect (weight bearing) in which the child stands with its pelvis lie posterior to the cassette as shown in the figure(4) below12, the other important position is Lateral both hips with frog projection in which the child lies supine on the table and a cassette is put under him, the medial sagittal plane of the child trunk is at rt angle to cassette midline as shown below in figure (5) .12  .

Perth’s disease typically involves the necrosis of the epiphyseal plate of the femur bone. Based on this concept, the early stages may incorporate the restriction of the epiphyseal plate and progressive accumulation of inflammatory fluid between the joints.

The radiographer is able to use the plain radiograph to detect these changes and stage the Perth’s disease as an early onset condition.

The late onset usually manifests through the remodeling and reshaping of the femur head. The plain radiograph is very critical in the late onset stages of the disease due to its ability to portray the various anatomical changes (13). This illustration is critical during the radiographic analysis because of its role in the identification of late-onset Perth’s disease.

The patient usually lies in a supine position during imaging of the pelvis remove it. For instance, the Caterall classification method is an illustration of a method that portrays the various changes in the bone (14).

Stage 1 usually indicates the diverse histological changes at the bone while stage 4 indicates the loss of structural bonds in the comprehensive acetabulum bone. One of the weaknesses of this method incorporates its lack of sensitivity during the early stages of the disease

Figure 1: show Radiographs of right hip show decrease the height of epiphysis of the femoral head and its sclerosis, and subchondral fracture 7

Figure 2:  Showing a plain radiograph of Perth’s Disease, Early Stage- Widening of the Joint of Hip, note the sclerosis of the head of Femur  (2).

 

 

 

Figure 3: Right-sided images is lateral Frog leg position view of 6-years old child with rt hip pain show the rt femoral head is seen sclerosed and flattened with some fragments, indicate avascular necrosis. the left side image of the same lateral frog leg position but only of rt hip which has a subcortical fracture of head of the femur.15

 

Figure 4: show A-P erect weight-bearing position adjustment of a child with Perth's disease, not the Ant.Sup iliac spine is at the same distance from the cassette and median sagittal plane. Gonadal protection must be done .12

Figure 5: show Child adjusted to take lateral both hip with frog projection x-ray view, note that the cassette must include both hips and centered at level of femoral pulse, window protection is applied 12

 

2- MRI

Fundamentally, MRI is a procedure preferred by certain radiographers due to its defined merits over the utilization of plain radiographs. It is fundamental to mention that MRIs utilize electromagnetic waves to depict images of the inner soft tissues.

Hence, it is capable of producing high-quality images that portray how Perth’s disease has resulted in the damage of femoral caput and adjacent bone (16). MRI images have more precision and clarity. In fact, in many cases, radiographers are capable of visualizing the abnormalities around the caput region using the MRI technique that isn’t visible on the plain radiographs.

Alternatively, the radiographers are able to choose between the T1 and T2 images so as to visualize the affected bone more precisely and visible. MRI imaging techniques are more elemental in Perth’s disease when it comes to the early diagnosis of Perth’s disease. The technique has a higher sensitivity rating compared to the plain radiograph (17).

MRI imaging is highly safe compared to other technique because it lacks radiation effects. Arthroscopy is another adjunct for the diagnosis and examination of Perth’s disease in the pediatric patient.

Critically, arthroscopy is an invasive technique that uses the idea of contrast media to visualize the affected anatomical regions (18).

This illustration elaborates why the procedure is very important when identifying the abnormalities brought about by the disease condition. Congruence, for instance, refers to the abnormality caused by the disease on the femoral head.

figure 6: T1-WI, post-contrast fat saturation show; the ossific nucleus of the Lt proximal head is not enhanced ( the white arrowheads), which indicate its necrosis.on the other side the hyper-enhanced region that surrounds the Lt femoral neck and head (black arrowheads) and the lateral portion of femoral head (arrow) indicate synovitis (10).

Figure 7: This Sagittal 2D T1-WI post-contrast fat saturated image shows the ossific nucleus of Rt proximal femoral head has centra necrosis, while the post and Ant femoral head is spared. This image of seven years old child complaining of rt hip pain (10).

Figure 8: Rt Image is Coronal STIR MR sequence show hyper-intense signal of Rt hip joint (white arrowheads) and rt sub-chondral epiphyses of the right proximal femoral head(black arrowhead).The Left Image is T1 WI coronal spin-echo MR sequence show hypo-intense signal of same rt femoral head (black arrowhead).. these findings of thirteen years old male child indicate Rt hip sub-chondral fracture (10)

3- Fluoroscopy (Arthrography).

The use of arthrography is an illustration of another imaging method which is fundamental in the assessment of Perth’s disease (19).

Arthrography of the pelvis, often, incorporates the utilization of fluoroscopy as an adjunct towards proper imaging. It is essential to note that arthrography involves the use of a contrast media that create distinct zones of the tissues, hence, increasing the rate of visibility (20).

But nowadays he loses his role to conventional MR as it makes a good job in the good assessment of congruity and contamination and assessment of prognosis with the need to get the risk of irradiation and intra-articular injection and risks of anesthesia.21Arthrography of the pelvis is capable of eliciting the congruence of the acetabulum in relation with the femoral caput.

This feature makes it a critical imaging technique for radiographers when assessing the impact of Perth’s disease on the mobility component of the patient.

4- CT Scan.

The CT scan is another fundamental imaging technique that visualizes the sclerosis patterns in the affected bone tissues. It is capable of detecting the earliest pathologic signs of Perth’s disease in patients. It utilizes multiple rays to visualize the changes occurring in the bone tissue. However, one significant limitation of the utilization of the CT scan is its radiation effect (22).

CT scans are capable of causing radiation damage to pediatric patients. Therefore, many radiographers avoid this method due to its potentially harmful effects on the internal organs.

Figure 9: these CT images which are oblique reformatted with the reconstruction of sixty-two years-old patient which have a late phase of Rt LCPD. The femoral head has lost its spherical shape,  give appearance of “mushroom”, there is also shortening and  broadening of neck of femur .there are also 2ndrys osteoarthritis and Acetabular remodeling 7

Staging:

There are multiple ways to do staging of Perth’s disease, one important is Catterall classification: Based on the extent of epiphyseal involvement while Salter-Thompson scheme: Based on extent and location of the subchondral fracture. Herring system: Based on lateral pillar (LP, lateral 1/3 of the femoral head) involvement (7).

 The Most reliable, reproducible that based on X-ray Imaging as following:

stage I: the early one, it’s asymmetric size of femoral epiphysis. and increase the density of epiphysis of the femoral head. And medial joint space Widening with the blurring of the physical plate. radiolucency of the proximal metaphysis (23).

stage II: fragmentation. subchondral lucency (crescent sign) with fragments of the femoral epiphysis with thickened trabeculae (23).

stage III: it’s called reparative in which begins the re-ossification and the femoral head shape become better. And enhance bone density (23).

stage IV: is the healed stage in which femoral head changes occur according to the severity. Some changes may occur like superior articular surface flattening femur head and neck widening (23).

 

Treatment:

Radiographers and orthopedic surgeons both agree to the fact that the goals of treatment of the disease condition include the elimination of hip irritability and the gaining of proper hip mobility.

Other goals include the attainment of a spherical femoral head and the prevention of epiphyseal collapse. This fact makes it critical for the health practitioner to make proper adjustments to the affected limb (24).

The use of the broomstick plaster is an illustration of an essential medical equipment that keeps the femur abducted and internally rotated. Moreover, other practitioners use the Scottish Rite brace to ensure that the limb is in the proper position.

Surgical therapy normally involves the use of femoral osteotomy as a form of therapy to ensure that the femoral head is in a proper position. Surgical techniques have indicated higher rates of prognosis compared to the non-surgical techniques.

To achieve these goals, most physicians say that contamination principles must be applied which based on that if the femoral head is fragmented and so not in hard condition, so the best is that it remains in the acetabulum in which it protects it, till it regenerates. 6

To begin contamination, the first step is to limit movement and protect weight-bearing. then nonsurgical options by Petria cast to make the head of the femur abducted and directed deep in the acetabulum. 6 the Surgical option of containment is as proximal femur osteotomy .6 After finishing the healing process, surgery is done to adjust the residual deformity.6

 

Complications:

Perth’s disease children have a risk of hip arthritis after being an adult, this occurs especially if healing occurs in an abnormal shape and the bones of the hip are not a perfect fit. So, the joint is liable to early wear and tear and surgery of replacement surgery is needed.25

 

Rehabilitation:

After Perth’s Surgery the physiotherapy is helpful in returning the patient previous healthy state as quickly as possible. As it assists in avoiding lower limb or back compensatory problems so he/she can restore the motion and strength as soon as possible.26

 

Conclusion:

Conclusively, radiographers utilize various methods to indicate the severity and progression of the condition in the pediatric child. Accordingly, radiographers are capable of assessing the stages of the Perth’s disease in the patient. Medical knowledge indicates that imaging usually serves an important step towards the process of diagnosis and disease assessment. Additionally, it provides an incentive to the radiographer regarding the management of the condition.

 

 

 

 

References:

 

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  2. Coley BD. Caffey’s Pediatric Diagnostic Imaging E-Book: Elsevier Health Sciences; 2013.
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  5. Larson AN, Sucato DJ, Herring JA, Adolfsen SE, Kelly DM, Martus JE, et al. A prospective multicenter study of Legg-Calvé-Perthes disease: functional and radiographic outcomes of nonoperative treatment at a mean follow-up of twenty years. JBJS. 2012;94(7):584-92.
  6. Kliegman, R. and Nelson, W. (2016). Nelson textbook of pediatrics. Philadelphia: Elsevier Saunders.Volume II. Neuromuscular Disorders.
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  8. What causes it? About Perthes Disease, published by The official site of Perth study group available at http://www.perthesdisease.org/perthes-disease-about.
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  14. Hosalkar H, Da Cunha ALM, Baldwin K, Ziebarth K, Wenger DR. Triple innominate osteotomy for Legg-Calve-Perthes disease in children: does the lateral coverage change with time? Clinical Orthopaedics and Related Research®. 2012;470(9):2402-10.
  15. Daldrup-Link, H. and Gooding, C. (2010). Essentials of pediatric radiology. Cambridge: Cambridge University Press. 2010 ISBN-13 978-0-511-78965-6.Chapter 5.
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  20. Shah H, Siddesh N, Pai H, Tercier S, Joseph B. Quantitative measures for evaluating the radiographic outcome of Legg-Calvé-Perthes disease. JBJS. 2013;95(4):354-61.
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