Evaluation of the Acutely Limping Child

Author: Arabella I. Leet, David L. Skaggs
Date: Feb 15, 2000

A limp may be defined as any asymmetric deviation from a normal gait pattern. The differential diagnosis of a limp includes trauma, infection, neoplasia and inflammatory, congenital, neuromuscular or developmental disorders. Initially, a broad differential diagnosis should be considered to avoid overlooking less common conditions such as diskitis or psoas abscess. In any patient with a complaint of knee or thigh pain, an underlying hip condition should be considered. The patient's age can further narrow the differential diagnosis, because certain disease entities are age-specific. Vigilance is warranted in conditions requiring emergent treatment such as septic hip. The challenge to the family physician is to identify the cause of the limp and determine if further observation or immediate diagnostic work-up is indicated. (Am Fam Physician 2000;61:1011-8.)

Normal gait follows a predictable pattern and uses energy efficiently. Gait can be divided into swing and stance phases: the swing phase forms 40 percent of the gait cycle, and the stance phase forms 60 percent. The most common form of limp, an antalgic gait, is caused by pain. To minimize weight bearing on an injured limb, the time in stance phase is shortened in the painful limb with a resultant increase in swing phase.

An acute limp implies an underlying pathology that causes disruption of the standard gait pattern; the challenge for the physician is to identify this pathology. The cause of a limp can range from something as serious as a life-threatening bone tumor to something as minor as a pebble in a shoe. The clinician must consider the spine, pelvis and lower extremities for a possible etiology. A useful approach is to consider the causes of limping from head to foot to avoid overlooking common underlying conditions such as diskitis, psoas abscess or septic hip, which are less obvious than conditions involving the lower extremities.

In considering the differential diagnosis of the acutely limping child, the clinician should first consider broader categories of etiologies, such as traumatic, infectious, neoplastic, inflammatory, congenital, neuromuscular or developmental causes (Table 1). Because certain diseases are more common in a given age group, the age of the patient provides critical information to narrow the diagnosis. For example, Legg-Calve-Perthes disease is rare in toddlers and adolescents but more common in boys four to nine years of age. Table 2 categorizes many etiologies of limping by age.

History

The child or caretaker should be questioned about the onset and duration of the limp and the association of the limp with pain. It is useful to ask if the limp is getting better, getting worse or staying the same. Usually a child whose limp shows signs of improvement may safely be observed as long as there are no constitutional symptoms. The older patient can localize a painful joint or focal area of pain, which is helpful in narrowing the differential diagnosis; however, referred pain patterns must also be considered (e.g., hip pathology causing knee pain). The very young child can rarely verbalize the location of the discomfort. In younger children, it is useful to ask the caretaker if the child prefers to crawl or walk on his or her knees; a positive response to this question makes foot pathology more likely.

A history of limp that appears worse in the morning suggests a rheumatologic process. Night pain, especially pain that wakes a child from sleep, is a worrisome indicator of a malignant process, and steps should be taken toward rapid diagnosis.

A diagnosis of "growing pains" must meet three criteria: (1) the leg pain is bilateral; (2) the pain occurs only at night; and (3) the patient has no limp, pain or symptoms during the day.1 To inaccurately diagnose a limping child with "growing pains" can be dangerous, as the physician risks missing the underlying pathology. However, if a child does fit the criteria for growing pains, the parents should be reassured that this is a benign, self-limited process that occurs for unknown reasons.

A review of systems should be completed to obtain a history of recent fever or other signs of infection. A recent upper respiratory infection could be the instigating event to a septic process or raise the possibility of poststreptococcal reactive arthritis.2,3 Fever suggests an infection or an inflammatory condition. A family history should also be obtained for rheumatalogic or neuromuscular diseases that may be inherited.

Physical Evaluation

In an antalgic gait, the gait is uneven because less time is spent in the stance phase of the affected leg. If the examiner is uncertain if a limp is present, listening to the sound of the feet hitting the floor may reveal an asymmetric cadence. A child who walks stiffly may be attempting to reduce pain in the spine, such as that occurring in diskitis. In a Trendelenburg gait, the torso shifts over the pathologic limb.4 This gait pattern is commonly seen in older adults with arthritis of the hip, although it also occurs in any condition causing hip inflammation or hip muscle weakness, including Perthes' disease and transient synovitis.

In a young child who clings to a parent and is hesitant to ambulate, the physician can separate the child from the parent and observe the child walking back to the parent. Having the patient run may bring out a gait disturbance not seen with walking.2

A focused neurologic examination should include observing the child walking on the toes, walking on the heels and hopping on one foot. Inspection of the feet may demonstrate clawing of the toes or cavus foot deformity, which are red flags for an underlying neurologic condition, especially if either condition is unilateral. The patient should be tested for deep tendon reflexes and clonus. The clinician should observe the patient bending forward to identify an asymmetric turning of the spine during flexion, another sign of spinal cord pathology. Limited spinal flexion accompanied by a stiff posture and local tenderness is suggestive of diskitis, which may sometimes be diagnosed with the use of plain radiographs (Figure 1).

In addition to testing spinal motion in flexion, the standing child should be asked to extend the spine by bending backward. Adolescents with spondylolysis or spondylolisthesis experience an exacerbation of lumbosacral pain with spinal extension. The sacroiliac joint may be involved in infectious or inflammatory conditions. On physical examination, the FABER test (consisting of hip flexion, abduction and external rotation) causes pain in the sacroiliac joint. This test is performed by placing the ipsilateral ankle on the contralateral knee in the supine patient and then providing gentle downward pressure on the knee (Figure 2).

Examination of the hip may be the most important part of the physical examination in a child whose site of pathology is not unequivocally localized, because hip pathology often results in vague pain and many hip conditions require emergent treatment. While infection of the knee or ankle joint may be readily apparent from swelling, tenderness, warmth and erythema, the hip joint is not as easily visualized, and the clinician must rely on indirect assessment on physical examination through range of motion.

Nearly all hip joint pathology causes increased production of fluid within the joint capsule.4 In children with transient synovitis of the hip, the mean intracapsular pressure is only 18 mm Hg when the hip is in 45 degrees of flexion, but it increases to 178 mm Hg when the hip is in extension and internal rotation.5 Clinically, this explains why a child with a septic hip keeps the hip in a position of flexion, abduction and external rotation. Conversely, the position of prone internal rotation is provocative in a child with hip pathology. Every child lacking a clear explanation for a limp should be placed prone, with the knees flexed and the ankles falling away from the body (Figure 3) so the physician can look for a difference in internal rotation between the hips. It is important that the pelvis be kept flat on the table, or the difference in internal rotation between the two sides may not be appreciated.

Hip abduction may also be tested with the hips flexed and extended, again making certain the pelvis remains level. Asymmetry in hip abduction may be indicative of inflammatory conditions of the hip, as well as developmental dysplasia of the hip (Figure 4). The Galeazzi test is performed by putting the child in a supine position and bringing the ankles to the buttocks with the hips and knees flexed. The test is positive when the knees are at different heights, suggesting developmental dysplasia or a leg-length discrepancy (Figure 5). Measurement of thigh and calf circumference should reveal atrophy (more than 1 to 2 cm of difference between sides) in a patient with any hip or knee condition that has limited function for more than one to two months.

14. Miralles M, Gonzalez G, Pulpeiro JR, Millan JM, Gordillo I, Serrano C, et al. Sonography of the painful hip in children: 500 consecutive cases. AJR Am J Roentgenol 1989;152:579-82.

15. Choban S, Killian JT. Evaluation of acute gait abnormalities in preschool children. J Pediatr Orthop 1990;10:74-8.

16. Aronson J, Garvin K, Seibert J, Glasier C, Tursky EA. Efficiency of bone scan for occult limping toddlers. J Pediatr Orthop 1992;12:38-44.

17. Leventhal JM, Thomas SA, Rosenfield NS, Markowitz RI. Fractures in young children. Distinguishing child abuse from unintentional injuries. Am J Dis Child 1993;147:87-92.

The Authors

ARABELLA I. LEET, M.D., is in private practice in Long Beach, Calif., and is an instructor at Orthopedic Hospital, a teaching hospital affiliated with University of California-Los Angeles. She received her medical degree from Columbia University College of Physicians and Surgeons in New York City and served a residency in orthopedic surgery at the University of Minnesota. Dr. Leet also completed a fellowship in pediatric orthopedics at DuPont Children's Hospital in Wilmington, Delaware.

DAVID L. SKAGGS, M.D., is assistant professor of orthopedic surgery at the University of Southern California School of Medicine, Los Angeles. He received his medical degree from Columbia University College of Physicians and Surgeons and served a residency in orthopedic surgery at Presbyterian Hospital, both in New York City. He is an attending orthopedic surgeon at Childrens Hospital Los Angeles and Cedars-Sinai Medical Center, also in Los Angeles.

Address correspondence to David L. Skaggs, M.D., Department of Orthopedics, Childrens Hospital Los Angeles, 4650 Sunset Blvd., Mail Stop no. 69, Los Angeles, CA 90027. Reprints are not available from the authors.

table 1Differential Diagnosis of the Acutely Limping ChildTraumaFractureStress fractureToddler's fracture (minimally displacedspiral fracture of the tibia)Soft tissue contusionAnkle sprainInfectionCellulitisOsteomyelitisSeptic arthritisLyme diseaseTuberculosis of boneGonorrheaPostinfectious reactive arthritisTumorSpinal cord tumorsTumors of boneBenign: osteoid osteoma,osteoblastomaMalignant: osteosarcoma, Ewing'ssarcomaLymphomaLeukemiaInflammatoryJuvenile rheumatoid arthritisTransient synovitisSystemic lupus erythematosusCongenitalDevelopmental dysplasia of the hipSickle cellCongenitally short femurClubfootDevelopmentalLegg-Calve-Perthes diseaseSlipped capital femoral epiphysisTarsal coalitionsOsteochondritis dissecans (knee, talus)NeurologicCerebral palsy, especial mildhemiparesisHereditary sensory motorNeuropathiesTABLE 2Differential Diagnosis of the Acutely Limping Child by AgeAll agesSeptic arthritisOsteomyelitisCellulitisStress fractureNeoplasm (including leukemia)NeuromuscularToddler (ages one to three)Septic hipDevelopmental dysplasia of the hipOccult fracturesLeg-length discrepancyChild (ages four to 10)Legg-Calve-Perthes diseaseTransient synovitisJuvenile rheumatoid arthritisAdolescent (ages 11 to 16)Slipped capital femoral epiphysisAvascular necrosis of femoral headOveruse syndromesTarsal coalitionsGonococcal septic arthritisTable 3Correlating History, Examination and Diagnostic Studies Physical examinationCategory History may show Laboratory studies RadiologyTraumatic Fall Localized pain, swelling, loss of None unlessinfection is Plain films, motion possible bone scanInfectious Fever, chills, erythema, pain Rigid guarding, warmth, CBC, ESR, CRP, joint Plain films, MRI, erythema aspirate bone scanNeoplastic Night pain, pain unrelated to Mass CBC, ESR, CRP,alkaline Plain films, MRI/CT, activity phosphatase, calcium, bone scan, electrolytes, joint aspirate staging work-upCongenital Problem since birth Deformity, leg-length discrepancy, None Plain films loss of ROMNeurologic Ataxia, loss of balance, High/low muscle tone,increased/ Creatine kinase (if DMD is Plain films disorganized gait decreased deep tendon reflexes, in differential diagnosis) cavus foot or claw toesInflammatory Pain [GREATER THAN]6 months, family Warmth/erythema, one or more CBC, ESR, CRP, joint Plain films history of rheumatoid joints aspiration arthritisDevelopmental Painless limp (LCP disease) Loss of ROM in joints,asymmetric None Plain films Knee pain (LCP disease, SCFE) ROM, pain with ROMCBC = complete blood count; ESR = erythrocyte sedimentation rate; CRP =C-reactive protein; MRI = magnetic resonance imaging;CT = computed tomography; ROM = range of motion; DMD = Duchenne'smuscular dystrophy; LCP = Legg-Calve-Perthes; SCFE = slipped capitalfemoral epiphysis.

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