Pediatric Transient Synovitis of Hip

Introduction:

Inflammatory conditions in young kids are always a great cause of worry in the child’s family because they cause constant pain and anxiety. However, some inflammatory conditions tend to subside on their own without causing long-lasting effects. One such condition is the synovitis of the hip or irritable hip.

What Is Transient Synovitis of Hip in Children?

Transient synovitis of the hip is also known as toxic synovitis or irritable hip. In this condition, there is inflammation of the lining of the joint (the synovium of the hip joint) in children. As the name says, this condition is transient (temporary) and resolves with adequate care. The disease is most frequently reported in children aged between three to ten years. This is also considered to be the most common cause of hip pain with sudden onset in children.

How Does Transient Synovitis of the Hip Occur in Children?

Etiology for Transient Synovitis of Hip:

The exact causative factor for transient synovitis of the hip in children has not yet been identified. However, some factors are considered to be interlinked in the causation of this synovial inflammation in children like:

• A recent medical history of viral attack, especially an infection of the upper respiratory tract manifesting as a cold or cough.

• Exaggerated immune response.

• Trauma to the hip and pelvic region.

• Allergic response.

Pathogenesis:

When the child has a viral infection, the body tries to protect the child by initiating an immune response. This immune response triggers inflammation and causes resultant inflammatory products to accumulate in the circulating blood. Such inflammatory products can deposit within the synovium of the hip joint to cause transient synovitis of the hip in children. Other triggering factors that cause transient synovitis of the hip are minor trauma to the hip region or an allergic reaction.

In transient synovitis of the hip, there is an accumulation of the synovial fluid and effusion in the hip joint. This can put constant pressure on the child and cause constant hip pain in the affected children. The hip joint is a vulnerable region for this condition because it is situated in a deep area and also acts as a stress-bearing joint. This is the reason children can easily pinpoint pain in the region.

What Are the Clinical Features of Transient Synovitis of the Hip?

• Children will not have the strength to walk and perform any activities.

• Refusal to participate in active sports.

• Limping.

• Constant pain in the hip and thigh region. Sometimes, this pain can radiate to the back and knee region.

• Range of motion becomes limited in the child. The activities that involve rotation or abduction of the hip may not be possible by the child due to intense pain.

• Pain will always be unilateral.

What Is the Differential Diagnosis for Transient Synovitis of Hip?

Since all the clinical features are vague and non-specific, differentiating this kind of synovitis from other inflammatory diseases is very difficult as they also pose similar clinical presentation.

Such conditions include:

• Septic Arthritis - In this condition, there is joint destruction due to the action of septic products produced by infectious agents. Since this is a consequence of infection, children may present with high fever, extreme pain, and markedly elevated white blood cell count and erythrocyte sedimentation rate.

• Perthes Disease - In Perthes disease, there is death of the femoral head of the joint due to lack of vascularity in the region (avascular necrosis). This can also cause limited mobility and should be differentiated from transient synovitis of the hip in children by radiographic examination.

How Is Transient Synovitis of the Hip Diagnosed in Children?

• Medical history and physical examination will give details about the incidence of synovitis in the hip region.

• Laboratory investigations to confirm the inflammatory process in the body include complete blood count test to look for elevated white blood cells, erythrocyte sedimentation rate, and C-reactive protein test. All these counts will be marginally elevated and significant elevation directly signifies an infectious attack (due to septic arthritis) rather than an inflammatory process.

• Joint effusion in the hip region of the children can be elicited through an ultrasonographic examination. However, this examination process is a non-specific one and further investigations are certainly required to diagnose transient synovitis of the hip in children.

• Bony abnormalities (like Perthes disease) can be eliminated through X-rays of the hip region. In transient synovitis of the hip, the X-ray tends to appear normal or may show a slightly widened joint space, primarily due to effusion in the joint space.

• In rare cases, doctors may advise an MRI to evaluate the status of the regions surrounding the hip joint. This is not indicated in straightforward cases of transient synovitis.

How to Manage Transient Synovitis of the Hip in Children?

The management strategy for transient synovitis of the hip in children is to provide supportive and adjuvant care as the condition is largely self-limiting. Within one to two weeks, children may recover completely from the hip pain. In the due process, the main objective should be to provide local pain relief, reduce inflammation, and help the child psychologically reduce the anxiety associated with hip pain. The ways to achieve this objective are:

• Providing adequate time to rest. Parents should refrain from asking the child to be involved in any heavy activities. The affected kids should not involve in strenuous physical activities or weight-bearing works until the symptoms subside completely. If the hip pain is severe, children will be advised to take complete bed rest.

• To help in the pain relief process, medications like NSAIDs (non-steroidal anti-inflammatory agents) will be provided to the kids. Aspirin should not be given to relieve pain in children under 12 years of age. Some physicians also advise for localized administration of painkillers.

Prognosis:

With proper rest and intake of painkillers, children can get relief of their hip pain within a maximum of two weeks. If the hip pain remains even after two weeks, subsequent examination to rule out other causes of pain should be evaluated.

Conclusion:

Hip pain and limping caused due to transient synovitis of the hip is always benign. It does not cause permanent damage or destruction of the hip joint. Children will completely recover from the condition without any long-term sequelae. With the right kind of care and minimal rest, the affected kids will bounce back effectively.