The Limping Child: Meeting The Challenges Of An Accurate Assessment And Diagnosis
Author: Mark C. Clark, MD, FACEP, FAAEM, Associate Director, Pediatric Section, Department of Emergency Medicine, Orlando Regional Medical Center, Orlando, Florida
Children who seek evaluation for the chief complaint of a painful or painless limp provide a challenge to the emergency physician. Because children have limited verbal skills or ability to cooperate with the physical examination the etiologic diagnosis of a limp in a young child is often a unique challenge. The cause of limp encompasses a long list of possibilities, with treatment ranging from simple reassurance to major surgery. In most instances of the limping children, a delay in diagnosis is not a problem, but in a few instances it may be catastrophic. Limp is never normal, and both benign and life-threatening causes can present with the same type of limp. In this issue the author systematically reviews the differential diagnosis and evaluation of children presenting to the Emergency Department with this complaint.
The Editor
Limp is not that uncommon of a childhood emergency, presenting in one ED an average of 4 per 1000 visits.1 The assessment can usually be accomplished by a careful history and physical exam, with radiographs often confirming clinical suspicions. The limping child seldom requires involved diagnostic procedures.2 However it is not uncommon for children with recent onset of limp to remain undiagnosed despite a thorough initial evaluation. Such children may be managed as outpatients without further laboratory work-up as long as close follow-up is assured.
Diagnosing the cause of limp in the very young child is especially challenging because these children usually cannot verbalize a good history or cooperate during the physical exam. Other obstacles to diagnosis are that younger children have difficulty localizing pain, have referred pain (i.e., the hip vs the knee), unrecognized trauma, and confounding variables leading to prolong and complex histories (recent immunizations, fever, antibiotics, viral syndromes). As a result, the physician is unable to localize the precise site or source of difficulty and perform a focused evaluation.3
A normal gait should be smooth, rhythmic, and efficient. Gait consists of one stride by each leg. By convention, the gait cycle begins and ends with the right "heel-strike." The stance phase is 60% of the gait cycle and starts with "heel-strike," progresses to "flat-foot," then "heel-rise," and ends with "toe-off." The swing phase begins after "toe off" and continues with the leg and foot moving forward in the air until the next "heel-strike."2
Limp is defined as an uneven, jerky, or laborious gait, and is one of the most common presentation for lower extremity musculoskeletal disease in children.4 (See Table 1.) Three major factors cause a child to limp: pain, weakness, and deformity.
Because the limping child can be such a diagnostic dilemma, a thorough history is necessary to make a successful evaluation. Historical features that should be sought in a limping child are listed in Table 2.2,4 History of trauma may be trivial, but toddler’s fractures can occur with minor trauma that may not have merited consideration by the parent. Often a history of fever or recent or current viral infections may hinder the establishment of the diagnosis as traumatic. Furthermore, a history of trauma may serve only to mislead the physician as in cases of osteomyelitis of the long bones where a history of preceding blunt trauma may be elicited in one-third of the cases.
Children are poor at localizing the site of the pain causing the limp.9 Parents may have to point out what they suspect is the source of the problem.2 Children can even mislead the examiner about their site of pain because it is not uncommon to have hip pathology like slipped capital femoral epiphysis and Legg-Calvé-Perthes being referred to the knee.3
When examining the limping child, the physician needs to have the child sit on the parents lap to reduce the stress and encourage cooperation for a more adequate exam. The examiner will often know what area to examine in detail from just watching the child.2 The exam should start slowly while distracting the child with playful banter, gently palpating areas of least concern first, then working to site of expected pathology. The child is examined for muscle strength, muscular atrophy, joint tenderness (physeal and joint line), bony tenderness, bony deformity, joint effusion, range of motion (active and passive), and inflammation of joints, tendons, or muscles. The limping child is also evaluated for potential limb shortening by measuring leg length from the anterior superior iliac spine to medial malleolus of the ankle.
Special areas to examine include the skin for rashes that may be consistent with serum sickness, Henoch-Schönlein purpura, acute rheumatic heart fever, or Lyme disease. One should look at the soles of the foot for foreign bodies or calluses from improperly fitting shoes. Palpation of specific tendon or fascia insertion points will facilitate the diagnosis of Osgood-Schlatter’s disease, Sever’s disease, or plantar fascitis. An excellent test to discriminate articular hip disease vs. pararticular disease is the hip rotation test. The test is performed by rolling the thigh of a supine positioned child. It is positive in all traumatic, infectious, or inflammatory conditions of the hip. Finally the physician should examine the back and the abdomen to find any unusual causes for limping.
A gait of a child starting to walk is different from that of an adult.2 Infants walk with increased flexion of their hips, knees, and ankles, which gives them a lower center of gravity and makes balancing easier. The feet are more widely spread in relation to the shoulder width and externally rotated to give the child a wider base of support. Infants and young toddlers spend a smaller percentage of the gait cycle in single limb stance than adults. A small child walks at a faster cadence than an adult but slower velocity (due to shorter stride length). By 3 years of age, children exhibit a mature walking-pattern.2
Average milestones of development of locomotion are as follows: the infant sits at 6 months of age, crawls at 9 months, walks with assistance at 12 months, walks independently at 15 months, and runs at 18 months. Bowing of tibias (genu varum) of infants is normal up to age 2-3 years. The reverse, knocked knee (genu valgum), can be normal up to 2-4 years old.
When examining a child’s gait, the physician should have them walk multiple times up and down the corridor to hopefully obtain a natural gait and to lose the "clinic walk." It may be necessary to distract the child to achieve this goal. Having the child walk barefoot is ideal since it may uncover pathology that otherwise may be missed in the foot or toes. Parents may even have to point out their concerns.2 If these maneuvers fail to produce the limp, having the child run may help intensify the abnormality otherwise hidden by compensation.4
Most children who limp will need radiographs, but in a few cases the clinical findings will be diagnosed by themselves. Radiographs are obtained to attempt to diagnose fracture, osteomyelitis, Legg-Calvé-Perthes disease, slipped capital femoral epiphysis, bone lesions (malignancy, osteochondroses, benign tumors), and congenital abnormality. Unfortunately it is not uncommon for a limping child to present without any history of trauma and a totally normal physical exam. Two retrospective studies from the same institution have looked for occult radiographic findings in these normal appearing but limping children. The larger study of 500 preschoolers and with vaque inclusion criteria found occult fractures in 20% of these children. In the smaller study of 84 preschool children with clear inclusion criteria, no children were found to have a significant radiographic abnormality (95% CI, 0-3.6%). These last investigators concluded that in a well-appearing child with an otherwise normal physical examination results, an acute gait disturbance is likely to be a self-limiting condition and radiographs are unlikely to contribute to the diagnosis. Initially, negative x-rays can be seen in stress fractures, salter fractures, early osteomyelitis, and septic arthritis.4
Some experts recommend comparison radiographs of the normal extremity routinely,3 while others recommend only when needed.4 The physician’s experience and the particulars of the radiographs in question should be a better guide about when to order comparison views. One study of the practice of pediatric radiologists found that they needed comparison views in extremity injury in only 8% of the cases.20 The same held true for radiology residents.20 In another study, comparison radiographs of the uninjured elbow did not improve diagnostic accuracy in pediatric elbow trauma for physician trainees, emergency physicians, or pediatric radiologists.21
Bone scan is very sensitive to any alteration in the bone’s metabolic rate, but is not specific. It is helpful in localizing the problem. Another way of viewing a bone scan is as an "atomic sedimentation rate".2 Bone scintigraphy is most helpful in diagnosing osteomyelitis, discitis, avascular necrosis, osteiod osteoma, and stress fractures.2,4,23
In a prospective bone scan study, 50 consecutive toddlers limping for less than one week were entered if a qualified orthopedic surgeon could not localize a lesion or make a diagnosis by initial screening examination of history, physical exam, white blood cell count, erythrocyte sedimentation rate, and plain radiography. In 54% of the cases, the bone scan proved essential in localizing lesions and no infections were missed.22 Bone scans were performed in 56 preschool children under 5 years of age with limp, refusal to walk, or lower extremity pain. Patients with fever, and those known to have infection, child abuse, malignancy, or radiographic abnormalities were excluded. More than half of the bone scans were abnormal and about half of the abnormalities were in the feet. Until recently, fractures of the foot have been considered rare, but presently bone scintigraphy has shown that occultly limping toddlers with normal radiographs can have tarsal fractures of the calcaneus and cuboid. The clinical significance of these fractures is questionable since all seemed to heal without sequelae.24,25,26
When additional information is needed to support the diagnosis of transient synovitis, ultrasound has been shown to be useful in confirming hip effusions found in this disease. A difference of more than 2 mm between the anterior joint capsule and the femoral neck is considered significant.27
No studies have specifically examined the efficacy of screening laboratory tests in the limping child. In the afebrile child with noninflamed joints, screening laboratory tests on the initial visit are usually not indicated. In the limping child with an inflamed swollen joint where septic arthritis is in the differential diagnosis, then synovial fluid analysis by arthrocentesis is the test of choice. Unfortunately, a relatively common presentation of limp in children is transient synovitis of the hip, which is not easily distinguished from septic arthritis of the hip. Laboratory evaluation of the venous blood is performed to help differentiate these two diseases. In this group of children with hip pain and no clearly identifiable source (normal x-rays and no history of significant trauma), an erythrocyte sedimentation rate of more than 20 mm/hr or a temperature of more than 37.5°C should be considered for diagnostic hip aspiration (97% of septic arthritis will be detected, but 50% will have unnecessary hip aspiration). The white blood cell count does not have any value in separating out these two diseases.28,29 A C-reactive protein value may be more specific than erythrocyte sedimentaion rate in septic arthritis. 29
Only one study has specifically investigated the various causes for the acutely limping child. Unfortunately this population was skewed since it studied children in a tertiary pediatric orthopedic clinic.3 The other studies have looked at several subsets of the limping child. A relatively large retrospective investigation examined 425 children with acute or insidious gait disturbances and included children who not only limped, but also refused to walk, or had ataxia or paralysis.1 Callahan published a review of 55 children who were admitted for refusal to walk.5 Illingworth reported a survey of 128 children with no obvious cause for limping (no evidence of fractures on radiographs, infection, or trauma).6 No one has yet examined children who just limp and present to a general practice or ED. Nevertheless, a quite extensive list for the causes of the limping child is known, which can be further broken down into etiologies based on age, and on causes that are life or limb-threatening. (See Tables 3-5.)1-6,9,22-26
Specific Causes of the Limping Child
Transient Synovitis of the Hip. Transient synovitis is the most common cause of nontraumatic hip pain in children.30,31 In Finland, of all children presenting with arthritis, transient synovitis of the hip represents 50% of all the cases. It is even eight times more frequent than septic arthritis of any joint.31 The cause is unknown and believed to be most commonly a post-viral illness sequelae, but trauma and allergic hypersensitivities have also been implicated.30,32 Transient synovitis occurs in children from 9 months old to adolescence, but it typically appears between 3 and 8 years of age, peaking at 6 years of age. It is more common in boys and characterized by an abrupt onset of unilateral hip pain, usually no fever to a low-grade temperature elevation, antalgic limp, and restricted hip motion (preferentially held in abduction and external rotation). The child does not appear systemically ill.30 The erythrocyte sedimentation rate is normal to minimally elevated. The white blood cell count is not helpful in discriminating these cases from septic arthritis.28,30 It is recommended if the temperature is greater than 37.5°C or the ESR greater than 20 mm/hr, then diagnostic arthrocentesis should be considered to exclude septic arthritis.28 Radiographs are performed to exclude other diseases. Some authors recommend ultrasound to confirm the presence of a hip effusion found in transient synovitis.27,28 Treatment is simple and consists of bedrest and mild non-steroidal antiinflammatory medication. As its name implies, transient synovitis usually has a limited duration of symptoms. The duration is less than one week in 67% of patients and less than four weeks in 88% of patients.30
Toddler’s Fractures. Toddler’s fractures occur in children 1-4 years of age. The mechanism of injury is usually trivial, such as tripping or twisting the ankle or falling from a low height.34 A mechanism of injury was found in 35 of 37 cases in one study, which supports that toddler’s fracture results from an acute traumatic event, not a stress fracture.34 On physical exam, there is no finding of bruising or deformity. The child typically has local tenderness, and sometimes has local swelling or warmth. Some children have no physical findings. Most children will not bear weight on the injured extremity.34 However, one author believes that toddler’s fracture can be excluded by holding the knee and ankle and twisting the lower extremity in opposite directions. If the fracture is present, pain will be elicited.35 Radiograph findings are subtle and consist of a faint obliqued lucent line crossing the distal tibia and terminating medially. It is usually seen on the anteroposterior view, poorly seen on the lateral and well seen on the internal oblique. Initial radiographs may be normal. Toddler’s fracture is a distal tibia fracture and should be considered as accidental trauma when no mechanism of injury is given; however, midshaft tibia fractures highly suggest presence of child abuse.34
Starshak et al reported 10 cases of calcaneus fractures in toddlers who presented with an acute limp. The fractures were detected with bone imaging which was performed when initial radiographs were noncontributory.36 The calcaneal fracture has been considered very rare in toddlers. The same findings were essentially published by Moss et al in four children, and they noted that two children presented with a consistent type of limp, namely flexion of the knee and hip and plantar flexion of the foot. Moss et al believe that the large amount of cartilage and the immature trabecular pattern in young children’s calcanei, cause fracture to exhibit minimal, if any, disturbance of the bony architecture on x-ray examination.35 Blumberg et al described four cases of cuboid fracture in acute limping children after a fall.24 Although initial radiographs were negative, early bone scintigraphy revealed focal uptake in the cuboid. Follow-up radiographs demonstrated characteristic sclerosis of a healing fracture in cancellous bone. These authors conclude that these cuboid fractures represent another clinically subtle toddler’s fracture and recommend greater awareness, a more careful foot examination, and closer attention to follow-up radiographs of the foot of any toddler with a persistent limp after trauma.24 Englaro et al performed bone scans in 56 preschool children with normal radiographs and lower extremity pain or gait abnormalities of unknown etiology.23 More than half of the bone scans were abnormal, and about half of the abnormalities were in various tarsal bones of the foot. They were surprised by this finding and felt they represented toddler’s fractures of the foot as discussed above.23
Slipped Capital Femoral Epiphysis. Slipped capital femoral epiphysis is usually a slow and chronic process of posteromedial displacement of the upper femoral epiphysis on the neck of the femur. More precisely, capital femoral epiphysis remains stationary in the acetabulum, and the femoral neck moves anteriorly and laterally.36,38 This is a disease essentially limited to late childhood and adolescence. Although the condition is well known, there are numerous reasons for delays in diagnosis. These include late presentation, failure to appreciate mild complaints, or failure to recognize subtle radiographic changes. Since prognosis is influenced by the amount of slippage present at the time of diagnosis, early diagnosis is important.37 These children need immediate referral to an orthopedic surgeon and must be kept non-weight bearing.
Slipped capital femoral epiphysis is a disease of the growth spurt period, occuring earlier in girls than boys. Adolescents who are obese or tall, thin and growing rapidly seem to be at increased risk.38 Patients with slipped capital femoral epiphysis frequently exhibit delayed skeletal maturation and a few endocrinopathies and family history of slipped capital femoral epiphysis.37 In adolescence as compared to childhood, there is periosteal thinning and widening of the physis which makes the capital femoral epiphysis more susceptible to shear forces.37,38
Children presenting with slipped capital femoral epiphysis most commonly are between the age of 13 and 15 years for males and 11 and 13 years for females. Blacks are affected more frequently than whites. Children who live in the eastern part of the United States have an increased incidence. Interestingly, the left hip in males is affected more frequently than the right. Bilateral disease is found in 25%, but recently computed tomographic studies have shown the incidence of bilateral involvement to be much higher.38
The most common presentation is chronic: This type is characterized by the gradual onset and progression of symptoms for more than three weeks, unmarked by any sudden exacerbation. Acute slip is characterized by a sudden onset of symptoms, and with less than three weeks’ duration. Acute on chronic slip is characterized by sudden exacerbation of symptoms due to acute displacement of the physis in a chronic slip.37
Initial presentation of chronic slip reveals that the disease process often begins long before the onset of symptoms, whereas the presence of bilateral slips with only one side symptomatic demonstrates that slipping and symptoms are not always associated.37 Onset of symptoms are usually insidious with pain and antalgic limp being the most common complaints. The patient can develop a Trendelenberg limp. The pain is dull and vaque; it may be intermittent or continuous, and is exacerbated by physical activity such as running or sports. Pain presenting in the thigh or knee is not uncommon with slipped capital femoral epiphysis. Pain usually increases on the extremes of range of motion. A typical finding is that, as the hip is flexed, the thigh tends to ride into lateral rotation. The range of maximal hip flexion is restricted and, frequently, the patient cannot bring his thigh to his abdomen. Actual shortening of the affected limb is common in moderate or severe slip.37,38
In acute slip the patient is in severe pain and guards from all range of motion of the hip. The hip is held in marked lateral rotation and there is obvious shortening.38
Radiographic changes can be minimal to none in the preslipping stage. The earliest changes are widening and irregularity of the physis with rarefaction of the proximal epiphysis. The best view for slipped capital femoral epiphysis is lateral. This is usually obtained by the frog-leg view (in which the hips are flexed, abducted, and laterally rotated, with the knees flexed and the soles of the feet together). Since the slippage is initially posterior, the lateral views show this better. On the AP view of the hip, a line drawn tangentially to the superior femoral neck should intersect less of the epiphysis than the normal side.38
Legg-Calvé-Perthes Disease. Legg-Calvé-Perthes disease typically occurs in children between 3 to 12 years of age and is most common at 5-7 years of age. Boys are affected 3-5 times more than girls. The incidence of bilaterality has been reported as 10-12%. Blacks are rarely affected by this disorder and it is increased in incidence in low birth-weight infants and children with delayed bone age. It is familial in 10-20% of cases..39,40
The etiology is unclear. Historically Legg-Calvé-Perthes disease’s pathophysiology has been referred to as idiopathic avascular necrosis. There is evidence suggesting that instead of being a single event of epiphyseal infarction, Legg-Calvé-Perthes is a disease that has repetitive infarction with attempts at revascularization.39 Children do not become symptomatic until revascularization and resorption of bone cause the necrotic subchondral bone to fracture and collapse.39
Children present with a history of insidious onset of limp that progresses to an antalgic limp and a Trendelenberg gait. Initially, pain is usually mild to none and is often referred to the anteromedial thigh or knee. There is loss of internal rotation and abduction of the hip. Sometimes the initial presentation is associated with trauma. Thigh and buttock atrophy can occur from disuse secondary to pain.39,40
Radiographically, Legg-Calvé-Perthes disease can be classified into four stages: initial, fragmentation, reossification, and healed. In the initial phase the capital femoral epiphysis fails to grow because of the lack of blood supply. The epiphysis appears smaller than the opposite side and widening of the medial joint space occurs secondary to epiphyseal cartilage hypertrophy. The physeal plate becomes irregular and the metaphysis is blurry and radiolucent. The epiphysis appears more radiodense than the opposite side. A subchondral radiolucent zone (the crescent sign) can develop, representing a subchondral fracture (typically seen in the anterolateral epiphysis). In the second stage, the fragmentation phase, the bony epiphysis begins to fragment and there are areas of increased radiolucency as well as increased radiodensity. In the third stage, the reossification phase, normal bone density returns to areas where there were radiolucencies. At this stage, alterations in the shape of the capital femoral epiphysis become evident. In the final stage, the healed phase, the proximal femur is left with any residual deformity from the disease and the repair process.39
The most universally accepted prognostic factor is age of onsetthe younger the child, the better the outcome. One possible explanation is that the younger the onset, the more time available for remodeling any deformity of the femoral head that was present after healing.39
Septic Arthritis. Septic arthritis in the limping child is a diagnosis that must not be missed. The single most important factor determining the outcome of septic arthritis is early diagnosis and treatment. Although any synovial joint may be affected, the knee and hip are by far the most common sites, with the hip predominating in infants and younger children.41 Ninety percent of septic arthritis is monoarticular.42 Outside of the neonatal period and early infancy, most children have fever and localizing signs. Physical examination shows joint effusion, severe pain on range of motion, and tenderness and warmth about the joint. Soft tissue changes are variable and depend upon the depth of the joint and duration of the infection.41,42 The erythrocyte sedimentation rate, which is the most sensitive test, is elevated in 90% of the cases, but it lacks specificity. The white cell count is elevated in only 30-60% of the cases and is also not specific. The definitive diagnostic test for septic arthritis is arthrocentesis.41 Plain radiography may show subtle signs of joint effusions including joint-space widening, soft-tissue swelling, obliteration of normal fat planes, or osteomyelitis.41 Radiography should be carefully examined for signs of osteomyelitis.43 Bone scans are difficult to interpret in septic arthritis and rarely indicated.42 Their primary use is to locate the source of the limp.22,44 In Chung’s one-year experience of acutely limping children in a tertiary care pediatric orthopedic clinic, only one child out of 148 children presented with septic arthritis.3 Singer examined a broader group of children for one year, any child with a gait disturbance who was admitted or seen at the ED. Fourteen children out of 425 had septic arthritis.1
Osteomyelitis. In 100 consecutive children who presented with a limp at the Children Hospital of Philadelphia emergency department, osteomyelitis was diagnosed in 2%.45 Chung, in a pediatric orthopedic clinic, saw 148 acutely limping children and three had osteomyelitis (2%).3 In children, osteomyelitis is most common in the first five years of life. Osteomyelitis characteristically involves a single long bone (93%) and primarily affects the femur, humerus, and fibula (67%). There is usually local tenderness and fever, but soft-tissue changes are usually late and more common in infants. Radiographic changes do not show bony destructive changes until 10-14 days after the onset of the infection. Loss of soft-tissue planes adjacent to the infected bone can be an early finding prior to bony changes.43 Bone scans are useful when the physical exam and plain radiographs are inconclusive and Nelson has reported that this occurs in approximately 30% of the cases.46
Discitis. There is not much known about discitis. It is a nonspecific inflammation of the intervertebral disk and is an uncommon disease that occurs almost solely in children. The incidence of this disease is not known, but it is a rare cause of limping and refusal to walk in children.5,22,42 Discitis is most common in children younger than 5 years old. The etiology is unclear, but the prevailing theory is that discitis is a low-grade bacterial infection where the host defenses eventually overcome the infection.47 The most common site of involvement is the low lumbar spine. The onset of discitis is gradual and subtle. Children usually present with limp, and have refused to sit or walk over a progressive period of 1-4 weeks.47 The child often prefers the recumbent position. Back pain and paraspinal muscle spasm can be present. Children with discitis do not appear acutely ill and usually have low-grade to no fever.47
Plain radiography is usually normal at early onset, but at 2-4 weeks, progressive intervertebral disk space narrowing is typically apparent.
As the disease progresses, the vertebral endplates can become irregular and show erosions. Bone scan with technetium-99m will be abnormal before the onset of plain radiographic changes. Recently, computed tomograghy (CT) and magnetic resonance imaging (MRI) have shown more vertebral bone involvement than was previously suspected. Awareness of the CT and MRI spectra of this disorder is important so that it is not confused with more serious diseases. The treatment of discitis recommended by most authors is bed rest and immobilization. The administration of antibiotics is controversial, and most authors recommend their use when the patient’s symptoms are progressing or if there is evidence of more invasive disease.42-49 The most important aspect to this benign disease is to exclude more serious diseases such as vertebral osteomyelitis and spinal tumors.42
Congenital Dislocation of the Hip. Despite careful screening, occasionally a child will not present with congenital dislocation of the hip (CDH) until after walking age.2,51 In a tertiary pediatric orthopedic clinic, 148 children presented in one year with an acute limp, and six of these children were late presentation of CDH.3 Walking-age children with CDH present with a Trendelenberg gait, decreased hip abduction, and thigh pistoning. The child will often walk on the affected side toes to compensate for the shortening. Children who are walking seem to have more frequently bilateral involvement. This may be due to the lack of asymmetry on the physical exam, making it harder to diagnose earlier. Children with bilateral CDH present with a lordotic, swaying, "drunken sailor" gait which is pathognomonic.ii Other signs of CDH in an older child include a positive Trendelenberg test (inability to maintain the pelvis horizontal while standing on the limb with the dislocated hip) which occurs because the hip abductors are mechanically disadvantaged. When these children lay supine with their hips and knees flexed, their knees will not be the same height with unilateral CDH. Finally, there may be extra skin folds on the limb with CDH.li
Reflex Sympathetic Dystrophy. Reflex sympathetic dystrophy (RSD) is not a rare disease in children as once thought and it continues to be underdiagnosed and misdiagnosed. The average interval between the onset of symptoms and the first visit to the physician is 10 days but the average interval to the time of diagnosis is 12 months. It is more common in girls (5:1) and the mean age for children is 11 to 12 years old. Nearly all children have history of antecedent trauma, but the majority of the injuries are vaque and seemingly minor. Unlike adults, the majority of reflex sympathetic dystrophies in children involves the lower extremities.lii The cause of this syndrome is unclear, but the pathophysiology appears to be peripheral nerve dysfunction which results in sympathetic nerve hyperactivity. RSD should be suspected whenever the severity or character of the pain does not fit the pattern of injury and the pain is associated with extreme sensitivity to light touch (allodynia), episodic mottling, cyanotic discoloration of the skin, swelling, or a difference in the skin temperature between the injured extremity and the contralateral one. Atrophic skin changes and radiographic bone findings are rare in children with RSD.lii Dietz et al. described a unique sign of autonomic dysfunction not previously noted in children with RSD. The sign, tache cérébrale, is elicited by stroking the skin on the affected area with a blunt object and observing a persistent erythematous line.
Osteochondritis Dessicans. Osteochondritis dessicans is a condition in which a segment of articular cartilage with its underlying subchondral bone gradually separates from the surrounding osteocartilaginous tissue. It is a disease limited to young adults and children (12 years or younger). The cause of the disease includes multiple factors such as heredity, predisposition, ischemia, and trauma. It affects males three times as frequently as females. In children, osteochondritis dessicans most commonly affects the knee, but it can also occur in the ankle, the elbow and the patella. Characteristically, it affects bones at particular sites, specifically the medial condyle of the knee, the capitellum of the elbow, and the superior surface of the talus. Children can complain of intermittent pain that is exacerbated by activity, stiffness, swelling, clicking, and occasional locking. In weight bearing joints, it can present as an antalgic limp. At times, symptoms can develop suddenly, when the fragment apparently becomes completely detached and causes locking. Bony tenderness often can be found over the lesion. This is best elicited in the knee by palpating the lateral aspect of the medial condyle with the knee acutely flexed. In the ankle, tenderness can be found over the lesional area by markedly plantar-flexing the ankle joint and palpating the dome of the talus.
The radiographic picture is diagnostic. A well-circumscribed fragment of subchoncral bone is demarcated from the surrounding femoral condyle or affected bone by a radiolucent saucer or crescent-shaped line. The fragment usually appears denser than the surrounding bone. A tunnel view is often needed to see the lesion on the posterolateral medial femoral condyle.lv
Osgood-Schlatter Disease. Osgood-Schlatter disease is a traciton apophysitis of the proximal tibial tuberosity at insertion of the patellar tendon caused by repetitive microtrauma that produces a partial avulsion. It is most commonly seen in rapidly growing and athletically active adolescents. The typical patient is a 13-14 year old boy or the skeletally equivalent 11-12 year old girl who has undergone rapid growth the preceding year. Osgood-Schlatter is usually unilateral, but is found bilateral in 30% of the cases. The children are often involved in a sporting activity which places great stress on tibial tuberosity by repetive quadriceps muscle contraction, such as football, basketball, soccer, gymnastics and ballet. The pain is usually relieved with rest. Clinically, there is often a prominence of the tibial tuberosity with soft tissue swelling and occasionally a palpable bony mass. The child is exquisitely tender directly over this area and symptoms can be reproduced by extending the knee against resistance. The knee joint should be entirely normal since this is an extraarticular disease.
Osgood-Schlatter disease is diagnosed on clinical findings, but radiographic evaluation is performed primarily to exclude other bony diseases such as tumor and infection. Although radiographic changes are frequently seen in Osgood-Schlatter disease, there is no definitive radiologic criteria. Only irregularities in the tibial tuberosity of symptomatic children are considered indicative, since asymptomatic irregularities are seen in normal growing children. Other radiographic changes include soft tissue swelling, thickening of the patellar tendon, calcifications or a superficial ossicle in the patellar tendon.lvii
Most cases of Osgood-Schlatter disease resolve with conservative therapy and avoidance of activity that involve forceful contraction of the quadriceps muscles. There should be just enough restriction to control the symptoms. Rest provided by a knee immobilizer combined with a home program of isometric exercises to minimize muscle atrophy may be necessary in persisting cases.lvi
Stress Fractures. Like most fractures, stress fractures are not a result of a single traumatic event, instead they are a process resulting from repetitive loading which causes fatigue, and if the stress continues, an eventual fracture. Bone remodeling occurs in response to applied stress and consists of bone resorption, followed by new bone formation. Bone resorption is a more active process. When the remodeling process is complete, strong bone will be present along the lines of stress. If the applied stress is increased or is continuous during the period in which bone resorption predominates, a stress fracture can occur.
Hulkko surveyed patients with 368 stress fractures and found 9% occurred in children, 32% in adolescents, and 59% in adults. The most common areas of stress reactions in children (in decreasing order of frequency) were the tibia, fibula, pars intraarticularis, and the femur. Unlike the adult, stress fractures of the tibia in children are proximal. Stress fractures should be suspected when the history shows the child has tried to do too much too soon. The primary finding is bony tenderness over the fracture.
Radiographic changes take 1 to 2 weeks after the onset of symptoms. The first signs in cortical bone may be periosteal reaction with new bone formation or thin lucency in the bone. Frank callus, if it even occurs, takes 4 weeks to form after the onset of the stress fracture. Cancellous bone (eg. metaphyseal or calcaneus) typically presents radiographically as focal increase in density with bony sclerosis. If immediate diagnosis is essential and radiographs are normal, a bone scan will be abnormal within 3 days after the onset of pain. If diagnosis can wait, then follow-up with delayed x-rays will usually show plain radiographic changes of a stress fracture.lxi
Child Abuse. Apparently a child presenting with a limp secondary to child abuse is a rare event,i,iii but for the welfare of the child, it is a diagnosis that should not be missed. Fractures of child abuse occur most frequently in children less than three years old. Approximately 50% are in children less than one year old, whereas accidental fractures are comparatively rare in children under one year old. Musculoskeletal injuries that are specific for non-accidental in the child include metaphyseal-epiphyseal injuries, rib fractures, vertebral fractures, finger fractures in non-ambulant and avulsive fractures of the clavicle and acrominum process. Other fractures that are highly suggestive, if not specific for non-accidental trauma, include clinically unsuspected (occult) skeletal injuries; fractures inconsistent with the age of the child or history provided by caretakers; multiple fractures involving more than one skeletal focus; healing fractures or failure to seek medical attention early; fractures of different ages indicating repetitive episodes of trauma; and combination of skeletal and extraskeletal injuries.lxii, Metaphyseal fractures of the long bones, although they are known to be specific for child abuse, are much less common than diaphyseal fractures. Merten et al. found that non-accidental diaphyseal fractures were four times more frequent than metaphyseal fractures. The most frequently injured long bones are the femur, humerus and tibia. All fractures of the humerus in children under the age of three are strongly suggestive of abuse.lxii
Recent pathologic-radiographic studies indicate that the original concept of the metaphyseal "corner fracture" denoting focal avulsion to the metaphyseal margin is no longer valid. Histopathological studies show that this fracture actually is an entire plate-like separation of the immature part of the metaphyseal bone with the outside ossified ring of bone. Depending upon the plane of the radiographs, these fractures can appear as an avulsed "corner fracture", a "bucket handle" appearing fracture, or a linearly separated disk of bone. In fact, they all represent the same fracture which is pathognomonic for child abuse.lxiii
Osteoid Osteoma. Osteoid osteoma occurs primarily in children and young adults. Seventy percent of osteoid osteoma, are in patients younger than 20 years of age. Males are twice as likely to have this disease. Diagnosis can be challenging and is often misdiagnosed. The most common initial symptom is pain and it appears to be worse at night. Characteristically, the pain is relieved dramatically with salicylates. In children less than 5 years old the primary symptoms is pain (88%) and of nearly half of the children reported pain occurring primarily at night. Limp occurred in 63% of the children who have osteoid osteoma in the lower extremity. Other less frequent findings in children less than 5 years old are swelling, muscular atrophy, leg length discrepancies, bone deformities and muscle contractures. Classical radiographic findings of osteoid osteoma result in a well-delineated and smooth, regular, round to oval, small radiolucency (nidus). It can be located within the center of the cortex, against the inner surface to surface of the cortex, or less frequently between the cortex and the periosteum. The nidus can have calcifications within or be completely calcified. The most remarkable finding with osteoid osteoma is that it stimulates a dense, homogenous bony sclerosis extending outward from the nidus. Periosteal new bone formation in a convex shape also occurs with this reaction and can extend several centimeters.
Benign Acute Childhood Myositis. Benign acute childhood myositis is a unique disease that occurs during epidemics with Influenza A and B. Typically, severe muscle pain, tenderness, and sometimes swelling develop during the first week of an influenza attack. The calf muscles are usually most severely affected and the child will limp or refuse to walk. The calves are often exquisitely tender and if the child does walk, often does so on his toes. The serum creatine kinase is elevated (360 to 3250 IU/L)., Sympoms resolve over 1 yo 2 weeks without any residual effect.
Bone Tumors. Bone tumors are exceedingly rare, can begin with vaque symptomatology, and not infrequently present with trauma. For these reasons, bone tumors can be difficult to diagnose. Persistent pain or swelling may erroneously be attributed to some minor injury. Extremity pain should be alarming if it is nocturnal or occurs at rest. Knee pain is common in adolescents, but it should be remembered that the two most common site for bone tumors are the distal femur and proximal tibia.ii,,
Distinguishing a benign tumor from a malignant tumor radiographically can be straightforward. The most important characteristic of an intraosseous malignancy is its "margin" or interface with normal bone. The rapidly growing tumor, unlike benign tumors, does not allow the normal bone to develop sclerotic margins. Instead, there is no defined margin around the area of destruction, and it is impossible to know where the tumor begins and ends.lxviii A distinct radiographic sign with malignant bone tumors is "onion skinning," which can be seen as the malignant tumor grows repetitively past the periosteum causing periosteal reactions to lay down multiple layers of calcium. Another x-ray finding seen with osteosarcoma is the "sunburst" phenomenon, which occurs when malignant osteoclast lays down calcium along tumor blood vessels radiating perpendicularly from the tumor.lxix
Osteochondroses. Osteochondroses are a group of bony lesions that occur in growing bones, primarily in the lower extremity. They have characteristic radiographic changes of decrease in size, irregularity, and increased density of the involved bone. Gradual reossification occurs over one to two years., They can be confused with normal variants of development of the epiphyses and apophyses.lxx They can present with an antalgic limp and pain over the involved osteochondroses. The etiology is unknown but speculation includes avascular necrosis to mechanical stress on the developing center of ossification leading to changes that resemble avascular necrosis.lxx The last theory is supported by the fact that similar radiographic changes have not been reported in bones which centers of ossification are present at birth (calcaneus, talus, or cuboid).lxxiv
Köhler’s disease is an osteochondroses of the tarsal navicular. It is most common in children from 2 to 9 years old, with predominance at 4 years of age. The navicular will have irregular ossification and will appear smaller and more dense. There is no long term sequelae. Freiberg’s disease occurs most commonly in adolescent females and involves the head of the second metatarsal (68%), but can occur in the third metatarsal (27%), or the fourth metatarsal (5%). Physical and radiographic findings are similar to Köhler’s disease.
Sever’s disease and Sinding-Larsen-Johansson (SLJ) syndrome are classified as osteochodroses, just like Osgood-Schlatter disease, but most experts feel these diseases represent a traction apophysitis with repetitive microtrauma causing partial avulsion of the tendon insertion at the developing apophysis. Treatment for these osteochondroses is similar as in Osgood-Schlatter with decrease in activiy. Sever’s disease is located at the insertion of the Achilles tendon and Sinding-Larsen-Johansson syndrome at the attachment of patellar tendon to the inferior pole of the patella.lvi,lxx
Sever’s disease present commonly in the 9 to 11 years old children with heel pain, particularly with running and may present with toe walking. On physical exam the calcaneal apophysis is very tender, especially to tranverse compression. Radiographs are not helpful since many normal children have dense and fragmented calcaneal apophysis.lxxiii Sinding-Larsen-Johansson syndrome occurs in children of 10 to 13 years old and radiographic can be helpful by showing calcification at the tendon attachment to the distal pole of the patella.
Nonorthopedic causes. While most cases are related to orthopedic disorders (e.g. trauma, infection) clinicians must be aware that disorders of other organ sytems (e.g. GI-appendicitis, CNC-infection,stroke [Table 4] can cause acute limping. Thus a thorough head to toe evaluation is required on all children without a clear cut source for their limping.
Acute limping is not an uncommon for children presenting to the emergency department. Clinicians must have a thorough understanding of the myriad causes, and appropriate steps for evaluating this complaint. A knowledge of the utility and limitations of diagnostic adjuncts will help to increase diagnostic adjuncts will help to increase diagnostic accuracy. Early and accurate diagnosis has the potential to impact the health and development of children with this complaint.
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