The following article is a part of conference coverage from the National Association of Pediatric Nurse Practitioners (NAPNAP) 42nd National Conference on Pediatric Health Care, held virtually from March 24 to March 27, 2021. The team at the Clinical Advisor will be reporting on the latest news and research conducted by leading nurse practitioners in pediatrics. Check back for more from NAPNAP 2021.
When a child presents with a limp, it is often better to first look for the horses (common causes) rather than the zebras (rare diagnoses), reported Lauren Roos, CPNP, RN, MSN, BSN, a pediatric orthopedic nurse practitioner (NP) at Stanford Children’s Health. Ms Roos offered guidance on how to evaluate, diagnose, and treat a limp in pediatric patients during a virtual presentation at the National Association of Pediatric Nurse Practitioners Annual Meeting (NAPNAP 2021).
When assessing deviation from a normal gait pattern, clinicians should consider the patient’s age, whether or not the limp onset coincides with trauma, presence and location of pain, presence of fever, and any other associated symptoms.
In addition to a physical examination, several options for diagnostic testing can help identify the cause of the limp. “Imaging with plain radiographs is always a good place to begin if you are concerned about osteomyelitis, fracture, or other bony abnormalities,” Ms Roos said, noting that radiographic bone changes do not occur until 7 to 10 days after infection.
If there is concern that the patient has septic arthritis of the hip (eg, fever, refusal to weight bear on affected leg, and no mechanism of injury), the most critical imaging to obtain is an ultrasound to determine if is fluid is present in the hip joint, Ms. Roos stated.
Magnetic resonance imaging and computed tomography scans can be part of a more detailed workup, but should not be used as the primary imaging methods. Ms Roos explained that the most important laboratory values to obtain are a complete blood count, C-reactive protein, erythrocyte sedimentation rate, as well as a blood culture.
The Horses: Common Causes of Limp in Pediatrics
Limps in children can be the result of infection (Table), trauma, pathologic disease processes, a neoplasm, inflammatory diseases, or neuromuscular diseases.
Table. Comparison of Infectious Causes of Limp
|Limp Cause||Toxic/Transient Synovitis (TS)||Septic Arthritis (SA)||Osteomyelitis|
|Risk Factors||Most common in patients aged 4 to 8 years; boys are twice as likely to experience TS. Recent illness is a risk factor.||Half of all cases occur in patients less than 2 years of age.||Mean age 6.5 years; 2.5 times more common in boys. The patient may have a recent local infection or trauma.|
|Presentation||Patient refuses to bear weight on affected leg, or limp has acute onset. The patient may or may not have a fever or history of a recent illness. The pain may improve throughout the day and respond well to NSAIDs. The child will appear otherwise well.||Patient refuses to bear weight on affected leg, or limp has acute onset. The patient may or may not have a fever, and severe hip pain gets worse as the day goes on. The child appears unwell, and the pain does not resolve with medication.||The patient may have an edematous, warm, swollen, tender limb on which they limp or refuse to bear weight. The child may or may not have a fever, and will have a restricted range of motion due to pain.|
|Diagnosis||Anteroposterior and frog lateral radiographs, as well as ultrasound if concerned about infection. MRI can help differentiate TS from SA, but requires sedation. Lab testing should evaluate CBC, CRP, and ESR values.||CBC, CRP, and ESR values should be taken immediately. The Kocher Criteria should be used as a guide for next steps. Hip aspiration is required to confirm diagnosis.||AP and lateral radiographs of the affected limb may appear normal at first, but show abscess at 1 to 2 weeks. CRP is elevated in 98% of cases; ESR is elevated in 90% of cases.|
|Treatment and prognosis||Prognosis is excellent; no long-term effects on hip joint. If low clinical suspicion of SA, treat with NSAIDs, observation, and activity as tolerated.||Treatment is emergent surgical incision and drainage of septic joint. The child will then need to be admitted for IV antibiotics, and continue taking antibiotics once discharged home.||Treatment includes surgical drainage, debridement, and IV antibiotics. Antibiotic treatment significantly lowers mortality to less than 1%.|
Pathologic Disease Processes
There are 2 pathologic diseases that may cause a child to present with a limp: Legg-Calvé-Perthes disease, an idiopathic avascular necrosis of the proximal femoral epiphysis, and slipped capital femoral epiphysis (SCFE), a disorder that leads to slippage of the epiphysis relative to the femoral neck. An unstable SCFE is a medical emergency.
Ms Roos stated that groin pull in teenagers is an “SCFE until proven otherwise,” as SCFE is the most common disorder that affects adolescent hips. Treatment for SCFE is surgery with in situ fixation; surgery to fix a stable SCFE can be delayed 1 or 2 days as long as the patient does not walk on the affected limb, but an unstable SCFE requires immediate treatment. The earlier an SCFE is caught, the better the prognosis.
Risk factors for SCFE include male sex and obesity. SCFE is also more common in Pacific Islander and Black patients.
The Zebras: Uncommon Causes of Limp in Pediatrics
In rare cases, a child’s limp can be caused by rheumatologic disorders like juvenile idiopathic arthritis, undiagnosed developmental hip dysplasia, and proximal weakness disorders such as muscular dystrophy. Both benign and malignant neoplasms can also cause limp.
Ms Roos noted the importance of differentiating between low-risk limp causes, such as TS, from medical emergencies, such as septic arthritis. When in doubt after trauma and injury are ruled out, ordering blood work can help identify the cause of a limp in pediatric patients.
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Roos L. The evaluation and management of the limping child. Presented virtually at: NAPNAP 2021; March 24-27, 2021.