MCQs In Pediatric Rheumatology and Orthopedics.

Q1 :

An 18-month-old girl presents to your office for an initial health supervision visit. The mother notes that the girl limps, and she thinks one leg is longer than the other. There is no history of medical attention for this problem in the adoption documentation. Review of available medical history and the current physical examination reveal no signs of illness. The child appears to be otherwise growing and developing normally. On physical examination, you measure a leg length discrepancy of 2 cm, and the girl has a “waddling” type limp and difficulty in abducting her right thigh at the hip. Of the following, the MOST likely diagnosis is

A. developmental dysplasia of the hip

B. femoral anteversion (internal femoral torsion)

C. Legg-Calvé-Perthes disease

D. slipped capital femoral epiphysis

E. vitamin D-dependent rickets

Answer :

A

Explanation :

Causes of Leg length discrepancy in a child:

-  It is seen most often in developmental dysplasia of the hip

 - Fracture

- Dislocation.

- Bone infection.

- Vascular malformation.

- Any process that may interfere with bone growth.

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Although abnormal hip abduction on physical examination in early infancy is the usual finding associated with hip dysplasia, older infants and children, especially those who walk, may present with waddling gait. One reason for the change in nomenclature from “congenital” to “developmental” hip dysplasia is that a subpopulation of children seems to present in later infancy or toddlerhood with hip dysplasia despite no findings on physical examination.

Development of the femoral head and acetabulum are intimately related, and normal adult hip

joints depend on further growth of these structures.

Hip dysplasia may occur in utero, perinatally, or during infancy.

 Asymmetric thigh or gluteal folds, better observed when the child is prone; apparent limb length discrepancy, as described for the girl in the vignette; and restricted motion, especially abduction, are significant, albeit not pathognomonic signs.

Developmental dysplasia usually is identified with abnormal Ortolani and Barlow maneuvers in early infancy and abnormal abduction until about 3 to 4 months of age.

Older infants and children may present with waddling gaits.

 Leg length discrepancy should prompt ultrasonographic evaluation  of the hip in the infant younger than 12 weeks of age.

 Plain radiographs with anteroposterior and frogleg views of the hip in the older infant and toddler can reveal hip dysplasia, healed fractures, ossification, and other abnormalities.

Failure to identify and treat developmental dysplasia of the hip may result in degenerative

changes of the hip and arthritis.

A number of other disorders may cause abnormal gait.

 Rickets normally presents with bowing of the legs, along with a “waddling” gait, and may be accompanied by other findings, such as swelling of the wrists or ankles or a “rachitic rosary” (enlargement of the costochondral junctions).

Legg-Calvé-Perthes disease  may cause pain and a limp, but typically occurs in children 2 to 12 years of age (mean age, 7 years).

 Slipped capital femoral epiphysis is a disease of the older, heavier preadolescent and is not seen in the

toddler/preschool age group. In contrast to these conditions, femoral anteversion (internal femoral torsion) causes intoeing, not a "waddling" gait or leg-length discrepancy. Typically, children present at 2 years of age or older and have increased internal rotation of the hips when examined in the prone position.

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Q 2

A 12-year-old female soccer player complains of intermittent left knee pain and swelling of 3 months' duration. There is no history of knee injury, but physical examination reveals swelling and tenderness to palpation over the left tibial tuberosity.

Of the following, the MOST likely diagnosis is:

A. anterior cruciate ligament tear

B.  medial meniscus tear

C.  Osgood-Schlatter disease

D.  patellar tendinitis

E   patellofemoral syndrome

Answer :

C

The most common causes of chronic anterior knee pain in the adolescent athlete are Osgood-Schlatter disease, patellar tendinitis, and patellofemoral syndrome. In these overuse injuries, repetitive microtrauma leads to the development of symptoms. The chronic left knee pain with swelling  and tenderness to palpation of the tibial tuberosity reported by the girl in the vignette is consistent with a diagnosis of Osgood-Schlatter disease.

In contrast to the conditions discussed previously, symptoms associated with a tear of the anterior cruciate ligament or medial meniscus generally follow an identified knee injury. Tear of the anterior cruciate ligament usually occurs when the knee is hyperextended or there is sudden deceleration. Patients often recall hearing or feeling a “pop” in the knee at the time of the injury. Acutely, the swollen and tender knee makes ambulation difficult. On examination, the Lachman test demonstrates excessive anterior tibial motion. In contrast, a tear of the medial meniscus causes anterior knee pain, locking (eg, an inability to extend the knee completely), clicking, and decreased range of motion. Physical examination reveals tenderness to palpation of the medial joint line and a positive McMurray test (eg, clicking along the joint line when the knee is flexed and extended with the foot simultaneously rotated internally and externally

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Q 3

A 14-year-old boy has had increasing pain and swelling in his left thigh over the past 2 weeks. He has been afebrile. Peripheral blood counts are normal, but erythrocyte sedimentation rate is 45 mm/h. Radiography demonstrates an osteolytic lesion in the midshaft of the femur with a surrounding soft-tissue mass. There is an “onionskin” appearance to the bony lesion.

Of the following, the MOST likely diagnosis is:

A.  aneurysmal bone cyst

B.  Ewing sarcoma

C.  lymphoma

D.  osteogenic sarcoma

E.  osteomyelitis

Answer

B

Leg pain in children and adolescents usually is benign and short-lived, but malignant bone tumors must be considered when the pain is increasing or recurrent. The primary site of Ewing sarcoma is divided almost evenly between the extremities and the central skeletal axis. In long bones, the tumor originates from the diaphysis, which distinguishes it from the typical metaphyseal presentation of osteosarcoma . Almost all patients who have Ewing sarcoma present with pain, and more than 50% have a palpable mass. The pain may remit for weeks or months. Hemorrhage and necrosis within the tumor can cause warmth and low-grade fever, which when combined with swelling, mimic infection and can delay the diagnosis. Pathologic fractures may occur. Routine radiographs usually reveal a destructive diaphyseal lesion. Erosion of the cortex and spread into the surrounding soft tissues sometimes is accompanied by a periosteal reaction that may be multilaminar, producing the classic “onionskin” appearance reported for the boy in the vignette.

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Q 3

During a school screening, a 12-year-old premenarcheal girl was noted to have a 6 degree scoliometer reading. No treatment was prescribed, but a follow-up visit was recommended. Six months later, the scoliometer reading is 12 degrees, and there is an obvious right thoracic deformity. Breasts and pubic hair are Sexual Maturity Rating (SMR) stage 3. The mother has a history of scoliosis that did not require treatment.

You are MOST likely to inform the parents that:

A.  early use of a brace will correct the curvature

B.  her SMR stage indicates the girl’s growth spurt is over and the risk of progression is minimal

C.  spinal radiographs should be obtained to assess the degree of curvature

D.  the ultimate magnitude of scoliosis will be similar to that of her affected mother

E.  this is a minimal degree of scoliosis that is unlikely to progress

Answer

C

Scoliosis , a lateral curvature of the spine, is considered abnormal if the curve is more than 10 degrees. The etiology is idiopathic in 85% of affected patients, and the condition usually is diagnosed during adolescence. Although a positive family history is a significant risk factor, no direct genetic link has been established. Congenital vertebral anomalies account for 5% of cases. The associated causes of the remaining 10% include other skeletal anomalies (eg, rib fusion), neuromuscular conditions (eg, cerebral palsy), hereditary disorders (eg, Marfan syndrome and neurofibromatosis), and compensatory scoliosis (eg, leg length discrepancy

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            Adolescent idiopathic scoliosis typically is a mild-to-moderate deformity that involves a radiographic curve or Cobbs angle of less than 30 degrees and is associated with no complications or long-term disability. Except for severe curvatures of greater than 45 degrees, the risk for curve progression ends with skeletal maturity. Other factors associated with curve progression include the magnitude of the curve at diagnosis, a thoracic curve, and the presence of a double curve. Idiopathic curves with a Cobbs angle greater than 45 degrees are at risk for progression in adulthood, and surgical treatment may be recommended.

            The Adams test is used to inspect the spine for scoliosis. The clinician stands behind the patient, who bends forward at the waist 90 degrees, keeping the knees extended. An elevation or “hump” indicates asymmetry of one side compared with the other. A scoliometer, essentially a protractor that resembles a level, provides a quantification of the asymmetry and aids in identifying progression or the need for further evaluation. A scoliometer reading of 7 degrees or greater correlates with a radiographic curve or Cobbs angle of 20 degrees. Radiographic curves between 20 and 30 degrees have a higher risk of progression in premenarcheal, skeletally immature girls compared with girls 2 years postmenarche.

            The girl described in the vignette is premenarcheal and has an obvious thoracic deformity, as evidenced by a scoliometer reading of 12 degrees. Radiographic examination with a standing posteroanterior, full spine film is the gold standard for evaluation of the degree of curvature. Referral to an orthopedic surgeon should be considered for any premenarcheal girl who has a Cobbs angle greater than 20 degrees and any adolescent who has a Cobbs angle greater than 40 degrees.

            Bracing will not correct the curvature, although it may help to slow the progression in skeletally immature patients whose curves are less than 40 degrees.

            Peak height velocity usually occurs after Sexual Maturity Rating stage 2 and before menarche. Accordingly, the growth spurt of the girl in the vignette is probably ongoing, and there is an increased risk of progression of the spinal curvature prior to epiphyseal closure.

            The daughters of mothers who have scoliosis are at increased risk, although the severity of the daughter’s scoliosis does not correlate with maternal severity.

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Q 4

An obese 10-year-old boy complains of pain in his right knee. There is no history of fever or trauma. On physical examination, there is no swelling or tenderness of the knee. His right leg is rotated externally, and he walks with a limp.

Of the following, the MOST likely diagnosis is:

A.  avascular necrosis of the femoral head

B.  iliotibial band syndrome

C.  osteomyelitis

D.  right anterior cruciate ligament tear

E.  slipped capital femoral epiphysis

Answer

E

Slipped capital femoral epiphysis (SCFE) (Figure 153A) results from failure of the upper femoral epiphysis, which allows displacement of the femoral head on the femoral neck. Onset may be sudden, but more often it is gradual. Pain frequently is referred to the knee, but it also can occur in the hip. Limp and out-toeing, as reported for the boy in the vignette, are common. Inflammation of the hip and posterior-inferior slipping of the femoral head lead to loss of medial hip rotation.

            The majority of patients who have SCFE are 7 to 15 years of age and are above the 95th percentile for weight. The increased weight adds to the stress on the hip and the mechanical failure of the growth plate. An anterior-posterior or frog-leg lateral radiograph of the hip generally reveals the abnormality.

            Iliotibial band syndrome is a common injury among runners because of the repetitive nature of their running activity. It involves inflammation of the iliotibial band from rubbing over the lateral femoral condyle, sometimes causing a snapping sensation during flexion or extension. Osteomyelitis often presents with fever and localized pain and should be considered in any child who has a limp. It usually is associated with an elevated erythrocyte sedimentation rate. A cruciate ligament tear generally results from significant trauma and is characterized by severe pain and an obvious knee effusion. The most common cause of avascular necrosis (AVN) of the femoral head is Legg-Calvé-Perthes disease, an idiopathic disease that occurs primarily in boys between ages 4 and 8 years. AVN may also be associated with prolonged steroid therapy. Pain is usually mild, and a limp may be present for several months before medical attention is sought. Loss of medial rotation and abduction are the primary physical findings.

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Q 5

A 14-year-old boy complains of intermittent unilateral knee pain occurring at night and unassociated with exercise. He has occasional morning stiffness that is relieved by exercise. Physical examination reveals decreased range of motion of the left knee, no erythema, and minimal swelling. There is also decreased range of motion of the lumbar spine in anterior flexion and loss of lumbar lordosis.

Of the following, the MOST likely result of laboratory studies would be:

A. elevated antistreptolysin O antibody titer

B. elevated leukocytes

C. positive antinuclear antibody

D. positive HLA-B27 antigen

E. positive rheumatoid factor

Answer

D

Intermittent oligoarthritis, especially in the lower extremities, night pain, and morning stiffness that is relieved by exercise, as experienced by the adolescent in the vignette, is characteristic of ankylosing spondylitis (AS). The findings on examination of his lumbar spine (flattening or loss of lumbar lordosis) also are classic for AS.

            Other associated signs of AS include hip and ankle arthritis and, occasionally, inflammation of the small joints of the feet. Localized tenderness also may be demonstrated at the insertion of the Achilles tendon or the plantar fascia. Although a history of low back or buttock pain should be sought, evidence of arthritis of the sacroiliac joints and spine may not be apparent for 5 to 10 years after onset.

            Extra-articular manifestations of AS are uncommon but include unilateral acute iritis, aortic valve insufficiency, and atlantoaxial subluxation.

            Confirmation of the diagnosis of AS by laboratory studies is difficult because many results are variable and nonspecific. The primary goal is to exclude other conditions that can mimic arthritis, such as sepsis, malignancy, and trauma. In a pediatric patient suspected of having AS, an erythrocyte sedimentation rate may be normal or elevated. The platelet count also may be elevated. Rheumatoid factor and antinuclear antibodies are universally absent. Results of human leukocyte antigen (HLA) studies are probably the most diagnostic because HLA-B27 is present in up to 90% of the AS population.

            Antistreptolysin O antibody titers are not elevated in patients who have AS. This test may be useful in the diagnosis of rheumatic fever.

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Q 6

A mother is concerned about her 12-year-old son's poor posture. On physical examination, you note dorsal kyphosis and increased lumbar lordosis. Radiography of the spine reveals anterior wedging of the upper thoracic vertebrae.

Of the following, the MOST likely diagnosis is:

A.  congenital vertebral deformity

B.  diskitis

C.  postural kyphosis

D.  Pott disease

E.  Scheuermann disease

Answer

E

Kyphosis ) refers to the convex alignment in the sagittal plane of the thoracic spine. The normal radiographic range of kyphosis is 20 to 40 degrees. Those who have increased kyphotic alignment have the clinical sign of roundback. Idiopathic roundback is referred to as Scheuermann disease.

            Scheuermann disease is a fixed kyphosis that develops around the time of puberty. It is caused by an anterior wedge-shaped deformity on one or more vertebrae, usually in the thoracic region, and affects 7% to 8% of the population. Patients present with a complaint of poor posture and possibly fatigue or an aching sensation in the region of the kyphosis. Findings on physical examination include accentuation of the normal dorsal kyphosis, increased lumbar lordosis, and a protuberant abdomen. A definitive diagnosis is only possible if posteroanterior and lateral radiographs of the spine reveal vertebral wedging of greater than 5 degrees.

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Q 7

A 28-year-old woman who has systemic lupus erythematosus is pregnant.

Of the following, the complication MOST likely to cause the infant's death in the neonatal period is:

A. cholestasis

B.  complete heart block

C.  glomerulonephritis

D.  intracerebral hemorrhage

E.  thrombocytopenia

Answer

B

Neonatal lupus erythematosus (NLE) is a rare disease caused by placental transfer of maternal immunoglobulin G autoantibodies. As many as 80% of mothers of infants who have NLE are asymptomatic; the remainder have been diagnosed as having systemic lupus erythematosus or another rheumatic disease. Maternal autoantibodies in infants who have NLE cause tissue damage that may affect the newborn’s heart, skin (Figure 210A), and liver. The major cause of morbidity and mortality is complete (third-degree) congenital heart block (CHB).

            CHB in NLE results from immune damage to the fetal cardiac conduction system and is associated with transplacental passage of maternal anti-Ro (SSA) and, occasionally, anti-LA (SSB) antibodies. CHB occurs in approximately 50% of infants who have NLE and, unlike other manifestations that resolve as maternal antibodies disappear, usually is permanent and complete. It may be asymptomatic or cause fetal bradycardia, intrauterine congestive heart failure, hydrops fetalis, or neonatal death. The infant who has CHB may require pacemaker insertion, although death rates as high as 15% have been reported despite this intervention.

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Q 8

A 14-year-old girl presents with joint pains, fever, chronic fatigue, and weight loss of 2 months' duration. Blood pressure is 160/100 mm Hg, and serum electrolyte levels are normal. Urinalysis reveals: specific gravity, 1.015; pH, 6.0; negative protein; moderate blood; 15 to 20 red blood cells; and 5 to 10 white blood cells. Laboratory tests reveal elevated antinuclear antibody (ANA) and anti-DNA levels and low serum complement levels (C3, C4). Therapy with oral steroids results in clinical improvement.

Of the following, the laboratory test result that would BEST indicate response to therapy is:

A. normalization of blood pressure

B. normalization of C3 and C4 levels

C. reduction of ANA levels

D. reduction of red blood cells in urine

E. reduction of white blood cells in urine

Answer

B

As a vasculitic condition, SLE may affect any organ system. Although the symptoms resemble those of various autoimmune and infectious diseases, the diagnosis is clear when there are high serum levels of antinuclear antibody (ANA) and double-stranded DNA (dsDNA or antiDNA), as described for the girl in the vignette. Low serum C3 and C4 levels and elevated Smith antigen confirm the diagnosis.
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Q 9 :

During a health supervision visit, the parents of an 8-year-old girl mention that she runs with an unusual gait. She had a history of developmental hip dysplasia that was treated conservatively with a Pavlik harness, but she has not seen her orthopedic surgeon for 4 years. Otherwise, she has been healthy and has normal growth parameters and development. Her examination results are normal except for a Trendelenburg gait, spine curvature with pelvic tilt, and slight limitation of hip abduction on the left side. She has normal strength bilaterally.

Of the following, the BEST next step in evaluating this patient is to:

A. obtain radiographs to evaluate degree of scoliosis

B. order a complete blood cell count and sedimentation rate to assess for an inflammatory process

C. measure her leg lengths to assess for discrepancy

D. refer her to a neurologist for evaluation for muscle disorders

E. schedule hip ultrasonography to monitor hip dysplasia

Answer:

C

The most accurate method of determining the amount of leg length discrepancy in the clinical setting is to place wooden blocks of known thickness under the foot of the shorter leg until the pelvis levels. Measuring the lower extremities is an alternative approach, but it has a higher error rate than the block method. Radiographic imaging also may be used to measure the legs. A standing radiograph from hip to ankle that uses a single long cassette demonstrates both mechanical alignment and angular deformities but lacks accuracy because of magnification and distortion. A scanogram prevents distortion, but the child must hold perfectly still for 3 separate exposures. This method also does not provide an accurate depiction of angular deformities. A computed tomography scanogram is accurate and allows measurement in the face of fixed hip and knee contracture, but again, the patient must remain still throughout the procedure.