WORKUP	Section 5 of 11
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Lab Studies:

• Although children with a limp rarely require laboratory testing, a CBC and erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) level are usually the most helpful and often are requested by consultants. A blood culture should be considered for patients with limp and fever.

• Complete blood count

• Any abnormal value in the WBC count, hemoglobin or hematocrit, or platelet count warrants further investigation, especially for signs of neoplastic disease. Bone pain, which may cause a limp, is a subtle but early and important sign of neoplastic disease in children, namely, leukemia or osteocarcinoma.

• An elevated WBC count, ESR, or CRP level is helpful in differentiating an infectious etiology from a benign one, such as toxic synovitis. Patients with fever and point tenderness or joint edema may have osteomyelitis or septic arthritis. A markedly elevated ESR may be suggestive of an underlying rheumatoid condition if no clear infectious source or supportive clinical findings are found.

• Serum chemistries - Serum electrolytes including calcium, magnesium, and liver function tests

• Urinalysis
  • Hematuria may be associated with endocarditis, HSP, acute glomerulonephritis, and SLE.

  • Pyuria often is associated with appendicitis or salpingitis, both of which may result in a shuffling gait.

  • The presence of uric acid crystals may support the diagnosis of gout.

• Obtain sickle cell preparation if history of sickle cell disease is unknown.

• Obtain serum uric acid level if gout is suspected.

• Stool cultures - Salmonella enteritis and Yersinia infection may cause joint symptoms.

• Lyme disease titers

Imaging Studies:

• Plain radiographs often are obtained on the initial ED visit to evaluate for obvious bony pathology. Other imaging studies may be scheduled or obtained on an inpatient basis depending on suspicion of disease.

• Plain films should include views of the entire limb, bearing weight when possible. Consider spine films with associated pain or tenderness or any neurologic complaints.

• Bone scan

• Intravenous technetium 99m–labeled methylene diphosphonate tracer accumulates in areas of increased cellular activity and blood flow.

• Scintigraphy is useful in detecting early Legg-Calve-Perthes disease, osteomyelitis, stress fractures, and osteoid osteomas. Scintigraphy is 84-100% sensitive and 70-96% specific for osteomyelitis.

• Ultrasonography is particularly useful for diagnosing joint pathology and confirming the presence of an effusion and guiding aspiration. Ultrasonography is also used for evaluating the hip for effusions.

• Computerized tomography scan

• One advantage of the CT scan is the ability to visualize soft tissue as well as bone. CT can also help identify periosteal abscesses or pyomyositis in association with osteomyelitis.

• Tarsal coalition is one disorder that has been better studied since the advent of CT scanning.

• Magnetic resonance imaging

• This technique can distinguish living bone from dead bone, which is helpful in studying conditions such as Legg-Calve-Perthes disease or avascular necrosis. MRI can also help differentiate fracture from osteomyelitis.

• MRI also is one of the best ways to assess the CNS, including the spinal canal.

Other Tests:

• Joint or bone aspirates: Joint or bone aspirates should be obtained emergently if septic arthritis or osteomyelitis is strongly suspected.

• Aspirates should be sent for cell counts, glucose, and culture (including fungal).

• Aspirates may be analyzed for uric acid (gout) or calcium pyrophosphate (pseudogout) crystals.

• Cerebrospinal fluid
  • A CSF analysis should be obtained if meningitis is strongly suspected (ie, symptoms including fever, headache, meningismus).

  • Meningitis has been associated with limping, probably due to meningismus.

• Other tests (informational): These usually are obtained on subsequent visits (not on the first ED visit) with similar complaints of limp, unless given a very strong history of collagen vascular or rheumatoid diseases.

• Sickle cell preparation

• Lupus erythematosus (LE) preparation

• Lupus antibodies

• Antinuclear antibody (ANA)

• Anti-DNA (rheumatoid arthritis, scleroderma, SLE)

• Antimuscle antibodies (myasthenia gravis)

• Human leukocyte antigen (HLA) (specific HLA types are associated with various rheumatoid disorders)

• Rheumatoid factors

• Creatinine phosphokinase

• Aldolase

• Serologies such as Lyme disease, parvovirus, or antistreptolysin-O (ASLO)

Procedures:

• Sputum or bone aspirates

• Potts disease

• Tuberculous arthritis is rare but is becoming more common in association with immune deficiency states.

	TREATMENT	Section 6 of 11
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Prehospital Care: Splinting and transportation make up the majority of services that prehospital personnel render to a limping patient.

Emergency Department Care:

• Emergency care of the limping patient is broken into 4 segments as follows:

• Identification of the cause

• Relief of acute pain

• Initiation of therapy for the source of the limping

• Referral to the appropriate person for follow-up care

• Acetaminophen or ibuprofen usually is adequate for pain relief, although opiates or local or regional anesthesia may be required for more painful or extensive conditions.

• For fractures, sprains, and acute traumatic injuries, immobilization and pain relief may suffice.

• Reduction of dislocations and displaced fractures reduce discomfort.

• Whenever crutches are dispensed or prescribed, the provider has a duty to train the patient in the proper application, including walking forwards and backwards, plus ascending and descending a few steps. Document training in a chart note.

• Various fractures and sprains may require splints; knee immobilizers are particularly helpful.

Consultations: In most cases, the diagnosis is clear and no further consultation is necessary. Specific conditions may require consultation from the following specialists:

• Orthopedic surgeon

• Infectious diseases specialist

• Neurologist or rheumatologist

• Neurosurgeon

• Child protective services: Any child with an unexplained fracture or injury also should be referred for evaluation by Child Protective Services.

	MEDICATION	Section 7 of 11
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Pediatric patients with limping usually can be treated with nonnarcotic analgesic or nonsteroidal anti-inflammatory medications. Some require glucocorticoids, muscle relaxants, or anti-infectives. Opiate analgesia rarely is needed.

	MISCELLANEOUS	Section 9 of 11
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Medical/Legal Pitfalls:

• Be vigilant in the approach to the limping individual because some pitfalls do exist. Missing a case of septic arthritis or a fracture is hard to defend, as is missing a malignancy. Some of the conditions associated with limping that should not be missed include the following:

• Congenital hip dysplasia, dislocation

• Septic arthritis of the hip, knee, or ankle

• Slipped capital femoral epiphysis

• Fractures of the tarsal bones and some involving the ankles can be very subtle.

• Salter-Harris type I fractures are often missed and may lead to long-term growth disturbance. Patients with open physes and traumatic injuries should not be casually considered to have a sprain without adequate follow-up.

• Tumors of the CNS may cause a progressive loss of gait, and a history of deterioration demands investigation. Ewing sarcoma and osteogenic sarcoma can be devastating if early detection does not occur.

Special Concerns:

• A system to follow-up the radiologist's reading is essential when incidental tumors are identified.