ACR Appropriateness Criteria®

Clinical Condition: Limping Child--Ages 0-5 Years

Variant 1: Nonfocal clinical exam.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 2: Focal clinical exam (not septic arthritis).

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 3: Suspected septic arthritis.

Summary of Literature Review

Limping is a common clinical problem in childhood, and it can be a diagnostic dilemma. Limping is a specific type of gait abnormality due to pain. Typically, one must consider processes from the spine to the toes as potential causes of a limp, which makes the list of possibilities quite long. Children frequently are unable to accurately localize the source of pain, and when the pain is localized it may actually be referred from above or below the painful region, adding to the difficulty in diagnosis.

The conditions to be considered will depend in part on the patient's age. Common conditions leading to a limping child include soft-tissue or bone injuries; infection of the bone, soft tissues or joints; and neuromuscular, congenital, developmental, ischemic, and neoplastic processes.

In one prospective study of 243 children under 14 years of age presenting with a limp, the most common diagnosis was transient synovitis. There are many less common causes as well. The patient may have a self-limited problem, but could also have a traumatic, inflammatory, or neoplastic condition requiring diagnosis and treatment. Some entities such as septic arthritis require rapid diagnosis to prevent or limit adverse outcomes. Others can be diagnosed in a more temperate fashion, based on clinical course. A detailed history and complete physical exam are essential in assessing a child with a limp. In many cases, no imaging is required, while others may require extensive imaging evaluation.

No large prospective studies have been performed to evaluate imaging algorithms in the child presenting with a limp. However, studies have examined individual diagnoses that lead to this presentation. Even in children with trauma, there is discussion about the appropriate radiologic evaluation.

Plain-film radiography has been used extensively in evaluating the limping child. It allows for a rapid overview, and triage and is recommended in many imaging algorithms. Usually, radiographs of the entire lower extremity, including the feet, have been obtained due to the relatively high prevalence of occult fracture. However, studies by one group of investigators demonstrated that as many as 26% of lower-extremity radiographs in injured children could be avoided with only a 5% incidence of missed fractures if clinical criteria were used in selecting patients for radiography. Similarly, another group demonstrated that examination for gross deformity and pain on motion predicted lower-extremity fractures in the post-trauma setting, with 97% of children with fractures being correctly identified. In the limping child without a history of trauma, plain radiographs of the lower extremities are typically normal. Another group found that fracture was the cause of a limp in 20% of 500 preschoolers who presented with a limp, while another group found radiographic studies to be normal in 96% of patients presenting with limp, inability to bear weight, or frequent falling, and the few abnormalities identified were relatively insignificant. On the other hand, plain film is all that is required for detection of diagnoses such as slipped capital femoral epiphysis, permitting early surgical intervention.

Ultrasonographic evaluation has mainly been used in evaluating the irritable hip. Two groups of investigators found that ultrasound (US) was helpful as the primary imaging technique in transient synovitis, with radiography being unnecessary in uncomplicated cases. Another group found toxic synovitis to be the most common diagnosis in the child with a limp, and they routinely use US as the primary imaging modality, reserving plain film for cases where the US was negative. However, a false negative rate of 5% was reported in one study due to inadequate exams or very early scanning. Another group found similar findings, reserving radionuclide bone scans for those with positive findings on US. US guidance can also be useful in guiding joint aspiration to differentiate septic arthritis from toxic synovitis, particularly in the hip.

Aspiration is the gold standard in differentiating toxic synovitis from septic arthritis, but others suggest that not all effusions need to be aspirated. In a prospective study of 53 children who had undergone US-guided aspiration because of an irritable hip, one group of investigators found that fever, an elevated C-reactive protein level, an elevated erythrocyte sedimentation rate, lack of weight-bearing, and an elevated serum white-blood-cell count were predictors of septic arthritis. The probability of septic arthritis was estimated to be 98% when five predictors were present, 93% when four predictors were present, and 83% when three predictors were present. US can also detect alternate diagnoses such as osteomyelitis and Legg-Perthes disease.

Radionuclide bone scans have been shown to be efficacious in evaluating limping children younger than 5 years of age, particularly when the exam is nonfocal. One group of investigators studied patients without a history of infection, child abuse, malignancy, or radiographic abnormalities of the lower extremities and found that 30 out of 56 patients had abnormal bone scans. Another group studied a group of 50 patients who had no diagnosis after clinical, laboratory, and plain-films radiographic evaluation. They found that 54% of the patients had abnormal bone scans localized to a specific region. Bone scan also plays a role in diagnosis and prognosis in Legg-Calve-Perthes disease, where the scintigraphic finds may predict the severity of the disease progression. Fluorodeoxyglucose positron emission tomography (FDG-PET) imaging and leukocyte scintigraphy can be useful in chronic osteomyelitis, outperforming magnetic resonance imaging (MRI) and plain films in a study by another group.

Due to radiation concerns and the efficacy of other imaging modalities, the role of computed tomography is limited in the child with a limp. It can be useful in preoperative evaluation of known fracture and in identifying osteopenia in a small subgroup of children with negative MRI evaluation for stress fracture.

MRI is useful in a number of different conditions that lead to a limp in a child. It can detect many early stress fractures, detect early Legg-Perthes disease, and osteomyelitis. It may even help in differentiating toxic synovitis from septic arthritis, as bone marrow signal abnormalities are seen more commonly in septic arthritis. Whole-body MRI may also be helpful in children with multifocal lesions. MRI can also help in differentiating bone infarcts from osteomyelitis.

In summary, the evaluation of the child with a limp must start first with a detailed history and physical examination, including an analysis of gait. If the cause of limping is evident clinically (neuromuscular disease or minor trauma), further assessment may be unnecessary. If the patient's pain can be accurately localized clinically, appropriate radiographic views of the area should be obtained. However, if the source of the limp cannot be localized, a medical decision will first have to be made whether imaging assessment is initially required or if further clinical observation is appropriate. For patients who have persistent signs and symptoms, or a clinical assessment that points to the possibility of significant trauma, infection, or tumor as the cause of the problem, consideration should be given to performing additional plain films, US, MRI, or radionuclide bone scan.

Anticipated Exceptions

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