Chapter Outline
Abnormal Gait Patterns in Children 79
Special Considerations Based on Age Group 81
Differential Diagnosis of Limping in Children 82
Limping is common in children, and it may represent a diagnostic challenge for the orthopaedist. A painful or painless limp may be caused by myriad conditions, with the differential diagnosis ranging from the benign (e.g., an unrecognized splinter in the foot) to the serious (e.g., a septic hip or a malignant neoplasm). * It is important that the clinician approach each patient in a systematic and orderly manner to avoid missing or delaying the correct diagnosis.
* References .
A thorough history and physical examination are the first steps toward achieving this goal, † and they may lead to early identification of the underlying problem causing the limp. The joints are inspected for irritability, swelling, effusion, erythema, and warmth; the presence of muscle atrophy is noted and measured; and both active and passive ranges of motion are assessed. Particular attention is paid to the child’s gait. Because various pathologic conditions often produce a characteristic limp, careful observation of the child’s gait can be extremely helpful in diagnosing the cause.† References .
The need for ancillary diagnostic tests is based on the history and clinical examination findings. ‡ These tests may include laboratory studies, radiography, and, in some cases, ultrasonography, bone scintigraphy, computed tomography (CT), or magnetic resonance imaging (MRI). In general, for the younger child who presents with a limp but is otherwise normal on physical examination and appears well, the gait disturbance is likely to be self-limiting, and radiographs are unlikely to assist in making a diagnosis. Persistent symptoms, however, warrant further investigation.‡ References .
This chapter describes the different abnormal gait patterns associated with childhood limps (normal gait is described in detail in Chapter 5 ) and presents a general overview of many of the possible conditions that may be responsible for a limp. More thorough explanations of these disorders are provided in their respective chapters. Limps resulting from an obvious injury are not addressed. Disorders most commonly responsible for an abnormal gait generally vary based on the age of the patient. Thus to enable the clinician more effectively to address the diagnostic challenge of a limp, the special considerations of three different age groups—toddlers (1 to 3 years), children (4 to 10 years), and adolescents (11 to 15 years)—also are presented ( Box 6-1 ).| Toddler (1-3 yr) | Child (4-10 yr) | Adolescent (11-15 yr) |
|---|---|---|
| Transient synovitis | Transient synovitis | Slipped capital femoral epiphysis |
| Septic arthritis | Septic arthritis | Hip dysplasia |
| Diskitis | Legg-Calvé-Perthes disease | Chondrolysis |
| Toddler’s fracture | Discoid meniscus | Overuse syndromes |
| Cerebral palsy | Limb length discrepancy | Osteochondritis dissecans |
| Muscular dystrophy | ||
| Developmental dysplasia of the hip | ||
| Coxa vara | ||
| Pauciarticular juvenile arthritis | ||
| Rarities | ||
| Leukemia | ||
| Osteoid osteoma |
Abnormal Gait Patterns in Children
A child’s gait pattern can be affected by numerous factors, including pain or inflammation, weakened muscles, abnormal muscle activity, joint abnormalities, and limb length discrepancy. Each of these pathologic conditions produces a characteristic limp, which can be recognized by observing the movements of the pelvis and trunk and the position of the joints of the lower extremities as the child walks and runs. Familiarity with these abnormal patterns helps significantly in correctly diagnosing the underlying cause of a limp. Additional gait disturbance patterns exist; however, the abnormal patterns described here reflect the majority of conditions that may cause limping in a child.
Antalgic Gait
An antalgic gait, which is caused by pain in a lower extremity or occasionally in the back, is generally the most common type of gait disturbance in the limping child. In an attempt to avoid the pain, the child takes quick, soft steps on the affected leg (“short stepping”) that reduce the amount of time the extremity is in the stance phase of gait. If the source of pain is in the hip, the patient also leans toward the affected side during stance phase to decrease the abductor force across the joint. Because the unaffected limb is brought forward more quickly than normal in swing phase, it remains longer in stance phase. An antalgic gait can be caused by any condition that causes pain during weight bearing in a lower extremity, and the pain can originate from any part of the extremity, from the foot to the hip. Another form of antalgic gait may be observed in children whose pain results from spinal disorders such as diskitis or vertebral osteomyelitis. In such cases the child walks very slowly or refrains from walking altogether to avoid jarring the back and aggravating the pain.
Trendelenburg Gait
A Trendelenburg gait is observed in patients with functionally weakened hip abductor muscles, a condition that makes it difficult to support the body’s weight on the affected side. This gait disturbance is commonly observed in children with developmental dysplasia of the hip (DDH), congenital coxa vara, or coxa vara secondary to another disorder (i.e., Legg-Calvé-Perthes disease or slipped capital femoral epiphysis [SCFE]). In all these conditions the abductor muscles themselves are normal but are at a mechanical disadvantage. As a result, during the stance phase of gait, the hip abductors function ineffectively, and the pelvis tilts away from the affected side. In an attempt to lessen this effect, the child compensates by leaning over the affected hip. This brings the center of gravity over the hip and reduces the degree of pelvic drop ( Fig. 6-1 ). The characteristic pattern of the Trendelenburg gait usually is obvious after the child has repeated the gait cycle a couple of times. Because the child has no pain, the amount of time spent in stance phase on the affected side may be normal (this is distinctly different from an antalgic gait).
Proximal Muscle Weakness Gait
Weakness of the proximal musculature, as seen in children with muscular dystrophy, may cause limping in the older toddler or young child. The lack of hip extensor strength forces the child to walk with increased lordosis of the lumbar spine to remain upright. Gowers sign is often present as the child arises from a sitting position. The child must “climb up” himself by pushing off with the hands against the shins, knees, thighs, and finally the hips ( Fig. 6-2 ). As the proximal musculature, in particular the gluteus medius and maximus, weakens further, the child “lurches” back and forth over the hips to maintain balance.
Spastic Gait
A spastic gait, as is seen in children with cerebral palsy, is caused by hypertonicity and imbalanced activity among muscle groups. § Spastic hamstring muscles restrict extension of the knee and thus may cause the child to crouch at the knee and walk with a shortened stride length. Spastic quadriceps muscles may result in a stiff, extended-knee gait. Children with cerebral palsy often exhibit a scissoring gait secondary to excessive hip adduction throughout the gait cycle that results in difficulty moving the swing leg forward. Sustained activity of the gastrocsoleus may cause ankle equinus and toe-walking. A patient with hemiplegia may appear to be dragging the affected extremity.
§ References .
Usually the spastic gait is a combination of several of these findings. Lower extremity spasticity becomes even more apparent when the child runs, and subtle upper extremity posturing may be noted (i.e., elbow flexion, forearm pronation, wrist flexion, and clenched fist). In some cases, however, these gait patterns and the clinical presentation may be very subtle, thereby making the diagnosis difficult. For example, in patients with very mild hemiplegia in whom increased tone in the gastrocsoleus leads to slight ankle equinus, the only gait abnormality may be excessive hyperextension of the knee during the stance phase (needed to place the foot flat on the ground).Short-Limb Gait
Gait asymmetry is usually seen in children when limb length discrepancies are in excess of 3.7% to 5.5%. In an effort to keep the pelvis level throughout the gait cycle, the child walks on the toes of the foot of the shorter limb. The child may be forced to maintain flexion of the hip and knee of the longer extremity when it is in stance phase. Children with discrepancies of less than 3.7% to 5.5% usually are able to use a combination of compensatory strategies to normalize the mechanical work performed by the lower extremities.
Special Considerations Based on Age Group
Toddler (Ages 1 to 3 Years)
Determining the cause of a limp is most difficult in toddlers. It often is difficult to obtain a reliable history directly from them because they are unable or unwilling to talk or because they cannot accurately describe the problem. In addition, their parents may not recall minor incidents that can result in a limp, such as a splinter in the foot or a toddler’s fracture of the tibia.
Because toddlers often are apprehensive or frightened at the physician’s office, the least intimidating part of the examination should be conducted first. The examiner should observe toddlers’ gait while they are walking uninhibitedly with their parents and look for limited range of motion of the joints of the lower extremity to help localize an abnormality responsible for the limp. Other important findings include localized tenderness on palpation and evidence of inflammation, specifically erythema, heat, swelling, and pain.
Because the neuromuscular development in toddlers is immature, their normal gait pattern is distinctly different from that of older children and adults. To achieve better balance, toddlers walk with a wide-based gait, increased flexion of the hips and knees, and arms held out to the sides with the elbows extended. To maintain their balance during the gait cycle, they spend more time in double-limb stance. Because toddlers cannot increase their speed by extending their step length, they compensate by increasing their cadence, which may make their gait appear uncoordinated and quick. Increasing maturity is accompanied by smoother movements, reciprocal arm swing, and an increase in step length and walking velocity.
Although the most common reason that children limp is to lessen pain from an extremity, toddlers in particular often limp for other reasons. Painless disorders that can cause limping in toddlers include DDH, limb length discrepancies, and mild static encephalopathies, to name just a few.
Painless toe-walking in toddlers is a common indication for pediatric orthopaedic referral ( Fig. 6-3 ). The differential diagnosis of toe-walking in these young children primarily includes idiopathic, mild spastic diplegia, and hereditary spastic paraparesis. A thorough evaluation of the perinatal and family histories and close examination of the gait for underlying spasticity usually identify a neurologic or inherited cause. Some idiopathic toe-walkers have full range of motion, whereas others have limited dorsiflexion because of a shortened tendo Achilles. On occasion, further helpful information can be gained from a gait analysis study. Other, less obvious causes of toe-walking should always be considered, particularly if the toe-walking is asymmetric. If the toe-walking is idiopathic, conservative management with casting or bracing is used on occasion but has not proved effective. Surgical intervention is rarely needed.
Child (Ages 4 to 10 Years)
Evaluating a limp in this age group is easier than in toddlers because older children communicate better and are more cooperative. In addition, their gait is more mature. Normally, by 5 years of age the child has developed a stable velocity pattern, and an adult gait pattern is usually attained by 7 years of age. Because children in this age group usually are more interested in play than in ancillary gains, limping and complaints of pain should always be taken seriously. Parents may report that the child complains of leg discomfort, typically in the evening before bedtime, that is alleviated only after massage and, on occasion, medication. Before dismissing such discomfort as “growing pains,” the clinician should perform a thorough evaluation to rule out an underlying disorder.
Adolescent (Ages 11 to 15 Years)
The limping adolescent usually can provide the clinician with an accurate history. However, symptoms may be understated if the individual wishes to return quickly to enjoyable activities or exaggerated if the individual hopes to avoid unpleasant physical activity requirements. During a thorough evaluation the examiner usually can determine the true nature and extent of the condition.
Differential Diagnosis of Limping in Children
Inflammatory and Infectious Disorders
Transient Synovitis
Transient (toxic) synovitis of the joint is probably the most common cause of lower extremity pain and likely responsible for the majority of cases of limping secondary to an irritable joint. The condition is seen most often in children between 3 and 8 years of age and manifests with the rapid onset of hip pain, limited joint range of motion, and limping (or an inability to walk, if the condition is severe). Often, the child has a history of an antecedent viral illness.
Although the clinical presentation may mimic that of septic arthritis, patients rarely have a temperature higher than 38° C or indications of systemic illness. The white blood cell (WBC) count, C-reactive protein level, and erythrocyte sedimentation rate (ESR) usually are within normal limits. Radiographs are normally unremarkable. Ultrasound examination of the affected hip shows the effusion associated with transient synovitis ( Fig. 6-4 ). Aspiration of the joint may be necessary to rule out the diagnosis of septic arthritis. Analysis of the joint aspirate usually reveals a WBC count between 5000 and 15,000 cells/mL, with more than 25% polymorphonuclear leukocytes.
The primary aim of treatment is to expedite spontaneous resolution of the underlying inflammatory synovitis. This objective is best met with a brief period of bed rest and non–weight bearing in combination with the use of oral nonsteroidal antiinflammatory drugs. Light traction during bed rest may be beneficial. Routine aspiration of the joint has not been shown to be of therapeutic benefit. When the pain has subsided, the patient should be instructed to use crutches until the limp is no longer present. Clinical symptoms usually resolve gradually and completely over several days to weeks (average duration, 10 days), and the long-term outcome is generally favorable.
Septic Arthritis
Septic arthritis requires urgent medical management because of the potential for significant joint destruction ( Fig. 6-5 ). It must be differentiated from transient synovitis because both conditions produce a limp secondary to joint pain. During the acute phase, it is crucial that the clinician accurately distinguish between the two disorders. As a result, hospitalization of the child for clinical evaluation, laboratory investigations, and medical management is common.
Like patients with transient synovitis, patients with septic arthritis usually present with the acute onset of joint pain. The child may walk with a limp or refuse to walk because of pain. He or she may have a history of antecedent mild trauma to the extremity or concurrent infection or illness. Unlike transient synovitis, septic arthritis usually progresses to a febrile systemic illness, and the child has fever, chills, and malaise.
On clinical examination, the child holds the affected extremity immobile. Swelling of the joint, erythema, warmth, and tenderness on palpation may be noted. Passive movement of the affected joint through its range of motion causes the child obvious pain, as does weight bearing on the affected extremity. Some patients present with less dramatic findings, especially those who have been partially treated.
Unless the patient is immunocompromised, laboratory values (WBC count, C-reactive protein, and ESR) usually are elevated. Blood culture results may be positive in approximately 30% of patients with septic arthritis.
Kocher and associates introduced an evidence-based clinical prediction algorithm in 1999 that differentiated between septic arthritis and transient synovitis of the hip. Four independent clinical predictors were used: history of fever, non–weight bearing, ESR of at least 40 mL/hr, and serum WBC count of more than 12,000 cells/mL. The predicted probability of septic arthritis was less than 0.2% for zero predictors, 3.0% for one predictor, 40.0% for two predictors, 93.1% for three predictors, and 99.6% for four predictors. Although this prediction algorithm was found useful in improving the efficiency of care at the institution at which the algorithm originated, other investigators reported less success with this algorithm in differentiating septic arthritis from transient synovitis.
Except for signs of tissue swelling, radiographic findings may be negative when radiographs are obtained at the onset of symptoms. Radiographic changes secondary to bone infection typically do not become apparent until 7 to 10 days after the infection has started. Radiographic changes indicate a protracted active infectious process. In more advanced infection, erosion and joint space narrowing may be noted as the articular cartilage is destroyed. Bone scans are not required if the lesion can be localized to a joint or periarticular region or if the diagnosis of septic arthritis can be made based on findings from the history, physical examination, laboratory studies, and radiographs. If not, acute triphase scintigraphy is very accurate in localizing the abnormality. However, a bone scan may fail to identify infection if the scan is performed within 24 to 48 hours of the onset of symptoms. Under such circumstances, consideration should be given to 24-hour delayed imaging with the bone scan or supplemental MRI, especially if clinical suspicion remains high.
Joint aspiration is important to corroborate the diagnosis and identify the causative bacterial organism. The aspirate WBC count is generally between 80,000 and 200,000 cells/mL, with greater than 75% polymorphonuclear leukocytes. However, lower cell counts may occasionally be present if infection is identified in its earliest stages or as the cell count is on the rise. Gram stain is helpful in selecting the appropriate initial antimicrobial agent. Newer bacterial DNA tests can be performed on synovial fluid to confirm the presence of infection. These tests require a minimum of time and may have greater sensitivity than standard diagnostic tests, such as Gram stain. Commonly, the synovial fluid is culture positive unless the patient has recently taken antibiotics. Staphylococcus aureus is the most common organism associated with septic arthritis. Haemophilus influenzae, previously found to be a significant cause of septic arthritis in toddlers, is rarely seen today because of H. influenzae immunization. Kingella kingae is considered to be responsible for an increasing incidence of infection in this population. The identification of infection caused by this organism in children between the ages of 6 months and 4 years has been facilitated by improved culture techniques, specifically inoculating joint fluid into aerobic blood culture bottles.
Osteomyelitis
In the child presenting with a limp, if infection has settled into bone, it is usually the result of hematogenous spread. S. aureus continues to be the most common offending organism, and a methicillin-resistant subset is becoming more common. The clinical picture varies with the age of the patient. In toddlers and children osteomyelitis may manifest with localized swelling, pain, or pseudoparalysis and may be associated with the sudden onset of fever and a toxic state. In older adolescents the course may be more indolent, resulting in a delay in the diagnosis of hematogenous osteomyelitis.
Evidence of deep localized soft tissue swelling is often the earliest radiographic sign of osteomyelitis in toddlers. Destruction of bone, commonly in the metaphyseal region, usually is not appreciated until several days have passed.
Diskitis
Infection of the intervertebral disk may interfere with normal walking as a result of the associated back pain. In fact, the child may have stopped walking altogether. During the clinical examination, if asked to perform a task that requires bending downward (e.g., picking up an object from the floor), the child either will refuse to do so or will hold the lower back straight and bend only at the hips in an effort to prevent spinal motion.
Although the patient may not appear ill, the ESR is elevated in approximately 80% of patients with diskitis. Blood culture results may be positive and, if so, usually show S. aureus to be the causative organism. This can be verified by needle or open biopsy, but because S. aureus is so commonly found, biopsy normally is not necessary and currently is not recommended as a routine diagnostic procedure.
Early in the course of the infection, radiographs may be unremarkable. However, as the disease progresses over several days to weeks, radiographs may demonstrate narrowing of the disk space and irregularities in the vertebral end-plate ( Fig. 6-6 ). MRI shows marked inflammatory changes in the disk and adjacent end-plates. Scintigraphy can help corroborate the initial diagnosis and facilitate localizing the infection. To enhance the sensitivity of scintigraphy for early diskitis or vertebral osteomyelitis, single photon emission computed tomography (SPECT) images of the spine may be specifically requested. These images recreate scintigraphic images of the spine in axial, coronal, and sagittal planes and allow for improved visualization of subtle uptake in the inflamed vertebral regions.
