Margaret S. Wolff
Limp represents any alteration in gait and is a common reason for presentation to the emergency department (ED) for children (1). The majority of cases are the result of trauma, but a lesion of the central nervous system, spine, peripheral nervous system, intra-abdominal contents, hip, knee, ankle joints, feet, or any of the weight-bearing long bones can lead to an alteration in gait (2,3). This chapter discusses the approach and evaluation of the child with limp in the ED.
CLINICAL PRESENTATION
A detailed history and physical examination are essential in making the correct diagnosis. The caregiver and child should be questioned regarding any temporal relationships, patterns related to physical activity, posture during sleep, and the location of pain. In the nonverbal child, the parents may be able to localize the source of the child’s limp. A history of an acute traumatic event, such as a fall, twisting injury, direct blow, or penetration by a foreign body, should be obtained. A history of recent fever, current or recent antibiotic use, antecedent infectious process, or other ill exposures may help to determine an inflammatory or infectious etiology. Historical features which may suggest an etiology of the limp are listed in Table 242.1.
TABLE 242.1
Historical Features of Pediatric Limp
In the preschool-aged child, the initial examination can be conducted with the child on a parent’s lap. Begin with inspection and evaluate the position of the patient at rest. Examine the skin for evidence of hemorrhagic diathesis, occult trauma, penetrating wounds, rash, or infection. Soft tissue swelling and skin changes may suggest pyoderma, cellulitis, or a deeper plane infection. Evaluate for asymmetry of gluteal, thigh, and popliteal creases. Effusion or distension of the joint capsules of the hip, knee, or ankle may also aid in the diagnosis.
Only after inspection should the physician palpate for localized induration, warmth, or tenderness near the bones, particularly metaphyseal regions of long bones. Assess the degree of restriction of flexion, extension, abduction, and rotation. Palpate the spine in the midline, looking for paraspinal muscle spasm or scoliosis. Examine the feet thoroughly for embedded foreign bodies. If a thorough musculoskeletal examination has not revealed any abnormalities, perform a thorough neurologic examination including deep tendon reflexes, motor strength, cranial nerve function, and sensory deficits or nuchal rigidity. The patient should also be asked to stand and to attempt to walk.
DIFFERENTIAL DIAGNOSIS
Normal gait requires coordinated action of the entire lower extremity; therefore pain, weakness, or dysfunction at any level can lead to gait disturbances. Traumatic and infectious etiologies account for the majority of patients seen in the ED with limp (Table 242.2). Because of their frequency, overt or occult trauma and infectious diseases should be part of the differential diagnosis for any child with an acute gait disturbance (3).
TABLE 242.2
Causes of Limp in Children
Traumatic Etiologies
In early childhood, a spiral fracture of the tibia or fibula (toddler’s fracture) should be considered the probable diagnosis in an afebrile child less than 5 years old who suddenly refuses to walk or place any weight on a single lower extremity. The absence of direct trauma should not cause the physician to rule out the diagnosis, because these fractures may occur as the result of trivial, indirect injury associated with the child’s daily activity (4). Older children may limp from stress fractures of the femoral head, tibial tubercle, and tibial or fibular shaft. They also may limp from avulsion of the ischial apophysis, lesser trochanter, or navicular tuberosity, or from lacerations and compression of cartilage plates, fracture of the epiphyseal ossification centers, shaft fractures, and infractions at various levels of the long-bone metaphyses. These traumatic lesions may present singly or in various combinations and may be acute or more chronic (5). Trauma and repeated stress may be important factors in the genesis of slipped capital femoral epiphysis, transient synovitis, and Legg–Calvé–Perthes disease, three of the most common hip afflictions associated with antalgic gait (6).
Nontraumatic Etiologies
An early presumptive diagnosis for the cause of gait disturbance must be established for a few conditions (Table 242.3). Failing to consider these conditions at the initial encounter may lead to deformity, functional disability, or ultimate patient demise (7). Serious infectious diseases predominate among the nontraumatic conditions that can cause altered gait with serious late complications if not detected early (8). A history of fever should heighten concern for a focal cellulitis of the lower extremity, unifocal septic arthritis of a weight-bearing joint, and osteomyelitis of the femoral or tibial metaphyses (8).
TABLE 242.3
Disease States Associated with Limp that Require Prompt Recognition
Pain associated with osteomyelitis of the long bones is primarily located at the affected metaphysis. Direct pressure at the affected metaphysis produces extreme discomfort. Swelling is limited to the immediate metaphyseal area initially, but it can spread rapidly to involve an entire extremity or adjacent periarticular tissue. Joints adjacent to the infected metaphysis may have some limitation of motion caused by voluntary guarding or sympathetic effusion. Neck pain, back pain, and refusal to walk may signal the presence of osteomyelitis of the spine. Fever associated with back, buttock, or hip pain with gait disturbance may be the initial expression of osteomyelitis of the pelvis (9). Children are prone to nontraumatic osteomyelitis, so the diagnosis should receive consideration.
Patients with pyogenic arthritis are usually readily diagnosed because of the protective posturing imposed by joint capsule distention. When there is hip involvement, children assume a characteristic position of comfort (Fig. 242.1). If the knee or ankle is involved, it is erythematous, warm, swollen, and painful to palpate, with limited range of motion. Minimal active motion, extreme muscle spasm, and pain with passive movement are distinguishing features of pyarthrosis in weight-bearing regions. Rarely, children with pyogenic arthritis can present with more subtle symptoms mimicking transient synovitis (10,11).
FIGURE 242.1 Child with septic hip. He is holding his left lower extremity flexed and externally rotated at the hip, as is characteristic with bacterial infection of the joint. (From Fleisher GR, Ludwig W, Baskin MN. Atlas of Pediatric Emergency Medicine. Philadelphia, PA: Lippincott Williams & Wilkins; 2004).
Children with transient synovitis have a unilateral inflammatory reaction in the hip. These patients usually present with either acute or progressive discomfort in the hip, anteromedial thigh, or ipsilateral knee that eventually leads to an antalgic gait. There may be antecedent minor trauma, recent upper respiratory tract symptoms, or low-grade fever. A fever of ≤38.5°C should raise the suspicion of septic arthritis. Clinically, this condition may be indistinguishable from Legg–Calvé–Perthes disease. In both cases, children do not appear systemically ill. They choose a position with the thigh flexed, abducted, and externally rotated. They guard the hip during examination and have pain with internal rotation of the hip and, to a lesser extent, with hip extension (6). The peak incidence of Legg–Calvé–Perthes disease is between 5 and 7 years of age (12).
Hip, groin, abdomen, lower back, buttock, or upper thigh pain associated with fever and limping may occur with a psoas abscess. Like patients with septic arthritis of the hip, those with psoas abscess may assume the position of hip flexion, abduction, and external rotation. Rotation of the fully flexed hip is typically pain free. Several findings may differentiate psoas abscess from septic arthritis or osteomyelitis: the presence of abdominal guarding with tenderness in lower quadrants or a palpable mass in the iliac fossa or pelvic floor detectable by rectal examination. Patients also may have bulging of the flank with or without cutaneous edema, scoliosis, immobility of the spine with spasm of the paravertebral muscles, or decreased excursions of the diaphragm (13).
Deep-plane infection refers to suppuration that extends to the depth of fascia or muscle. In necrotizing fasciitis, fat and fascia are destroyed. Muscle is typically uninvolved, and skin, on occasion, may be spared (14). In bacterial myositis, the striated muscle is involved, and there may be localized abscess formation within the muscle (pyomyositis). Clinical features of fasciitis and myositis overlap. Neither disease is common in immunologically intact children. Predisposing conditions include diabetes mellitus, chronic cardiac or pulmonary disease, collagen vascular disease, varicella complicated by pyoderma, and antecedent blunt trauma. Symptoms are often insidious, starting with poorly localized extremity pain that impairs gait. Fever may be absent or only of low grade. Pain out of proportion to the degree of physical findings may be the only clue to the correct diagnosis at the initial encounter (14). Rapidly developing skin changes suggest the diagnosis. These changes include a localized soft tissue swelling, erythema, and either darker discoloration of the skin (pyomyositis) or bullae formation, and spontaneous sloughing (necrotizing fasciitis). If misdiagnosed at the time of initial presentation, children may return in extremis within 24 to 48 hours in septic shock (14).
In cases of acute or chronic slipped capital femoral epiphysis, deep groin pain and hip, distal medial thigh, or knee pain may be of sudden onset or progressive over weeks. Classically, pain is vague, dull at rest, and exacerbated by ambulation. Children seek comfort by externally rotating the leg when walking. They limp, is often accompanied by a truncal shift with ambulation to accommodate hip abductor weakness. Examination demonstrates a partially flexed, irritable hip maintained in external rotation. Maximal hip flexion is restricted, and complete internal rotation is not possible. Delay in recognition of an acute slip may result in further displacement or may increase the risk for avascular necrosis.
Pathology outside the musculoskeletal system may also present as limp. Patients with uncomplicated appendicitis, or a perforated or abscessed appendix may present with a slow cautious, gait accompanied by flexion of the trunk (15). Hip pain and limp may be the presenting complaints with epidural abscess, but most patients in this instance seek medical attention because of unremitting back pain. At the onset, most patients exhibit fever, headache, malaise, and aching midline back pain. Patients may have tenderness on palpation of the spinous processes at the level of their back pain. Overt cord involvement may be heralded by weakness of voluntary muscles and bowel and bladder sphincters or by sensory abnormalities, most often characterized as ascending anesthesia (16). Limp may be the initial presentation of systemic illness such as acute lymphoblastic leukemia or lymphoma (17). Systemic symptoms such as fever, weight loss, and night time pain may suggest these diagnoses.
ED EVALUATION
ED evaluation should be guided by history and physical examination (Fig. 242.2). When there is a history of trauma or the area of pain has been localized, radiographs limited to the area of interest have proven diagnostic efficacy. Plain radiographs are specific for fractures, destructive lesions, and avascular necrosis (18–21). Radiographs are often insensitive and unreliable, especially in the early course of patients with toddler’s (tibial) fractures, septic hip, osteomyelitis of the long bone or pelvis, sacroiliac joint infection, and intervertebral disk infection.
FIGURE 242.2 Algorithmic approach to the child with a limp. CRPS, complex regional pain syndrome; CBC, complete blood count; SCFE, slipped capital femoral epiphysis; AVN, avascular necrosis; DDH, developmental dysplasia of the hip; LCP, Legg–Calvé–Perthes disease. (From Gary RF, Stephen L, Fred MH, et al. Textbook of Pediatric Emergency Medicine. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.)
Patients with fever or systemic symptoms require a more extensive evaluation. Laboratory evaluation should include a complete blood, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and blood culture (if febrile). A CRP level >2 mg/dL is consistent with a septic joint or osteomyelitis when the clinical picture is suggestive (11,22–24). It is important to note that fever, leukocytosis, and elevated acute phase reactants may not uniformly accompany infectious diseases associated with gait disturbance (11).
In patients with fever or other systemic symptoms, further imaging is indicated if initial radiographs are negative and the suspicion is high for bacterial infection of the bone, joint, or soft tissue (24). Patients with hip irritability should undergo ultrasonography to assess for presence of an intra-articular effusion (25). Magnetic resonance imaging (MRI) is superior to both plain films and CT scans for soft tissue detail. MRI may be the most sensitive means of establishing an early diagnosis of Legg–Calvé–Perthes disease, differentiating bone infarction from osteomyelitis in the sickle cell patient and benign from malignant bone tumors. MRI may be useful in certain anatomic regions that are difficult to evaluate with plain films (e.g., region of the sacroiliac joint, vertebral bodies, and intervertebral disks) (18).
KEY TESTING
• Plain radiographs of affected extremities
• Blood cultures if febrile
• CBC
• ESR
• CRP
• Ultrasound of hips if indicated
• CT MRI for equivocal cases
ED MANAGEMENT
Rarely, a patient with limp, pseudoparalysis, or paresis requires establishment of an airway or ventilatory support or hemodynamic instability. If present, initiate prompt resuscitation prior to proceeding with evaluation of limp. Neurologic deficits may be rapidly progressive in a few conditions associated with gait disturbance. Continuous monitoring of neurologic status is warranted for patients suspected of having Guillain–Barré syndrome, poliomyelitis, acute transverse myelitis, tick paralysis, brain abscess, meningitis, or cerebral vascular accident.
For all patients with limp, ensure that any associated pain is well controlled. Additional management will vary depending on the history, physical and evaluation. Patients with traumatic injuries may require splinting, reduction of fractures, or operative repair, and consultation with orthopedics can be beneficial. Patients with fever should receive antibiotics if a source is located or if the patient is hemodynamically unstable. Septic joints require urgent arthrocentesis and consultation with orthopedics. Patients with suspected osteomyelitis or deep soft tissue infections not identified in the ED require admission for further evaluation such as MRI. In patients with presumed transient synovitis, a dose of ibuprofen can markedly improve symptoms and aid in diagnosis.
CRITICAL INTERVENTIONS
• Obtain plain radiographs in children with traumatic limp.
• Perform a thorough physical examination, including neurologic examination, in patients with nontraumatic limp.
• Order CBC, acute phase reactants, and blood culture for children with fever and limp.
• Patients with hip irritability and fever require prompt ultrasonography, and arthrocentesis if hip effusion present.
DISPOSITION
Admission is warranted for children with gait disturbance in certain circumstances. All patients who appear to have a serious bacterial infection require admission. Admission is warranted for all patients with neurologic abnormalities, such as altered consciousness, cranial nerve involvement, subjective or objective sensory disturbance, ataxia, alteration of sphincter tone, urinary retention, altered deep tendon reflexes, or loss of voluntary movement. Admit patients with gait disturbance who may have injuries due to nonaccidental trauma in consultation with child protective services.
Common Pitfalls
• Think of trauma when there is an abrupt onset of gait disturbance without prodromal events in a previously healthy child.
• De-emphasize the history of trauma, even if witnessed, when fever or systemic symptoms are present; this scenario suggests serious bacterial infection.
• Fever, leukocytosis, and acute phase reactants may not uniformly accompany infectious diseases associated with gait disturbance.
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