Pediatric Primary Care Case Studies (128 page)

   Legg-Calve-Perthes disease (LCPD)

•   Autoimmune: juvenile rheumatoid arthritis (JRA), also called juvenile arthritis (JA)

•   Hemoglobinopathy: sickle cell disease

•   Neoplasia: leukemia or tumor—benign or malignant

Limping is a common clinical problem in childhood. Limping is a gait abnormality due to pain (Fordham et al., 2007). Limping can be the result of a fracture, sprain/strain, or contusion. Overuse syndromes are more common in the school-age child and present as stress fractures, shin splints, Sever’s disease, apophysitis of the tibial tubercle (Osgood-Schlatter disease), and chondromalacia
patellae. A chronic limp can be the result of developmental hip dysplasia or leg length discrepancy. A history of a limp that appears worse in the morning and gets better with use suggests a rheumatologic process. Night pain, especially if the pain wakes the child from sleep, can be an indicator of a bone tumor. “Growing pains” often present as bilateral leg pain, with pain occurring at night, and no limp, pain, or symptoms during the day. Septic arthritis and transient synovitis both present with decreased motion of the hip. In the African American child with sickle cell disease, the differential diagnosis of osteonecrosis of the femoral head should be considered.

Trauma, resulting in strain, sprain, or fracture, is the most common cause of an acute limp in children. Fractures are more common than sprains and strains in the younger child. Child abuse should be suspected if the injury does not fit the history given, particularly if there is evidence of multiple fractures in different stages of healing or a spiral fracture indicative of a twisting mechanism of injury. Greenstick fractures, which are characterized as incomplete fractures, are seen only in children and are usually the result of a fall. Physeal fractures occur near joints and restrict or impede motion. Overuse syndromes such as Osgood-Schlatter disease (OSD) present as knee pain/limp due to repetitive activities such as running and jumping. OSD is more common in the older school-age child or adolescent (Beach & Ficke, 2007).

Repeated microtrauma with bone collapse following interruption of blood flow to the femoral head is thought to be the cause of Legg-Calve-Perthes disease (LCPD), also known as juvenile avascular necrosis. LCPD is caused by ischemic episode(s) that interrupt the circulation to the capital femoral epiphysis. It accounts for 2% of childhood limps in the 3- to 12-year-old. A positive family history is found in 10% to 20% of cases. Whites are more affected than Asian Americans, and Asian Americans more than African Americans. LCPD typically affects short, active boys with a delay in bone age (Mace, 2006). LCPD is characterized by persistent knee, thigh, or groin pain. The history may include intermittent pain after activity. There may be a painless limp. Physical findings may include atrophy of the quadriceps and thigh with adduction flexion contracture. Children with LCPD can present with an antalgic gait or Trendelenburg gait resulting from pain in the gluteus medius muscle.

Slipped capital femoral epiphyses (SCFE) is a disease frequently seen in adolescents. There is a slightly higher incidence in males and African American children. Incidence is about 1 case per 100,000 people (Adler, 2008). During a period of rapid adolescent growth, the growth plate separates from the femoral neck. A large number of children with this condition are overweight for height. Additional risk factors include malnutrition, endocrine abnormalities, history of chemotherapy, and prior developmental dysplasia of the hip (DDH). Children with SCFE typically have a history that includes hip pain (50%) or knee pain (25%) over several weeks or a minor fall or trauma resulting in inability to bear
weight (Adler). Physical findings include loss of complete hip flexion and ability to fully rotate the hip inward. The affected leg may appear shorter.

In an African American child, the possibility of complications of sickle cell disease has to be considered. Osteonecrosis of the femoral head is a common complication in patients with sickle cell disease. Children as young as 5 years of age who present with hip pain during an acute sickle cell crisis have been diagnosed with osteonecrosis of the femoral head (Neumayer et al., 2006). Osteonecrosis of the femoral head occurs in 90% of patients with sickle cell disease, and collapse of the femoral head occurs in 90% of patients within 5 years after the diagnosis of osteonecrosis. The prevalence of the complication peaks during adolescence (Neumayer et al.).

Musculoskeletal tumors, benign and malignant, are another cause for a limp. Malignant tumors, osteosarcoma, Ewing’s sarcoma, and rhabdomyosarcoma account for 5% to 10% of malignant neoplasms in children (Junnila & Cartwright, 2006b). Osteosarcoma most often presents in the teenage years during episodes of growth spurts, and presents as pain in the upper arm near the shoulder area or leg pain above or below the knee that awakens the child at night. The child might also have pain at rest. The physical exam may reveal a lump or swelling at the site.

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children; it occurs in 1 to 5 per 10,000 children, with peak incidence in children ages 2 to 5 years. Leukemia can present with nonspecific complaints of fever, bone, or joint pain (Junnila & Cartwright, 2006b). The pain is due to accumulation of blast cells in the bone marrow or joint fluid. The immature blasts crowd out healthy cells in the bone marrow.

Developmental dysplasia of the hip (DDH) can predispose a child to premature degenerative changes and painful arthritis. Hip dysplasia refers to abnormality in size, shape, orientation, or organization of the femoral head. Approximately 1 in 1,000 children is born with a dislocated hip, and 10 in 10,000 may have hip subluxation (Storer & Skaggs, 2006). Intrauterine position, sex, race, and a positive family history are the most important risk factors. A positive Galeazzi sign, inequality in height of knees in a supine position, is caused by hip dislocation or congenital femoral shortening. In the ambulatory child, a positive Trendelenburg sign or limping on the affected side may be a sign of a dislocated hip.

Benign nocturnal limb pains or growing pains present as cramping pains of the thigh, shin, and calf. They affect approximately 35% of children 4–6 years of age (Junnila & Cartwright, 2006b). Pain typically appears in the evening or at night and may awaken the child from sleep. Benign nocturnal limb pain is not associated with a limp (Junnila & Cartwright).

Juvenile rheumatoid arthritis (the most common type of childhood arthritis) can present with a limp. However, in a study by Junnila and Cartwright (2006b), 99% of children with pain as an isolated complaint did not have inflammatory disease. Systemic onset in children younger than 5 years will
include a history of febrile episodes and macular or maculopapular rash with only mild joint involvement. Prolonged morning stiffness, swelling, and symptoms of weight loss, fever, and fatigue are suggestive of an inflammatory process such as arthritis and vasculitis (Junnila & Cartwright, 2006a).

In a review of 64 cases with septic arthritis, 33% of the children had been seen by healthcare professionals prior to definitive diagnosis and 33% had been treated previously with antibiotics (Luhmann et al., 2004). Septic arthritis and transient synovitis of the hip can present in a child as both a limp and a painful hip. Accurate diagnosis of septic arthritis is critical because of poor outcomes associated with delay in diagnosis. Septic arthritis of the hip requires surgical drainage and use of intravenous antibiotics.

The most common pathogen in septic arthritis is
Staphylococcus aureus.
Fever, bone pain, swelling, redness, and guarding the affected body part are common. In the infant and younger child, inability to support weight and asymmetric movement of the affected extremity are often early signs. On physical exam, painful swelling and point tenderness over the affected area are cardinal signs of infection/inflammation.

Toxic synovitis (TS) presents similarly to septic arthritis and is most likely a viral synovitis or postviral reactive arthritis that causes inflammation and pain around the hip joint. It most commonly causes a limp with pain. In one prospective study of 243 children under 14 years of age presenting with a limp, the most common diagnosis was transient synovitis (Fordham et al., 2007). The child often has a history of recent upper respiratory infection, pharyngitis, bronchitis, or otitis media. The child with TS is usually afebrile or has a mildly elevated temperature; high fever is rare. The affected hip is usually held flexed, abducted, and externally rotated. The main difference between TS and septic arthritis is that the child with TS does not appear systemically ill. The condition is self-limiting. In review of laboratory studies, white blood cell count (WBC) and erythrocyte sedimentation rate (ESR) may be slightly elevated. Transient synovitis, a self-limiting problem, is treated nonoperatively with oral analgesics and observation.

Making the Diagnosis

To make the correct diagnosis, you need to know the cause of the limp. Certain laboratory and radiographic data will help. In addition, you need to consider the child’s age because certain pediatric orthopedic problems occur more often at one age than another.

What laboratory and radiographic data would help you make the diagnosis?

The workup for an irritable hip consists of a thorough history and physical examination along with plain radiographs of the hip and laboratory studies including a complete blood count (CBC) with differential, ESR, C-reactive
protein (CRP), and blood culture (Luhmann et al., 2004). Anteroposterior and lateral radiographs, ultrasound, and MRI may be needed to differentiate among stress fractures, Legg-Calve-Perthes disease, and osteomyelitis. Anteroposterior and frog lateral views of the hip joint can rule out SCFE, LCPD, bone lesions, or congenital abnormalities. In the nonverbal patient, a screening anteroposterior film from hips to feet may identify any occult fractures. Ultrasound of the hip is useful in identifying fluid in the hip joint.

What imaging or laboratory tests are indicated?

In a child in whom the presenting symptoms are inconclusive, radiographic studies, CBC, ESR, and CRP would be indicated. Depending on the results of the blood work, an ultrasound of the hip with needle aspiration would provide the most accurate diagnosis. Delay in treatment of septic arthritis of the hip can lead to destruction of the hip joint, growth plate, and avascular necrosis of the femoral head.

Transient synovitis of the hip can be identified by the healthcare provider based on the history and physical examination. An afebrile, nontoxic-appearing child playing in the examination room and walking with a slight limp of recent onset most likely has transient synovitis and is treated with close monitoring, without need for invasive studies (Caird et al., 2006). Observation of the child for a period of time can help to distinguish between TS and septic arthritis. Children with bacterial infection will rapidly worsen, and children with synovitis will often improve over time. In general, children with septic arthritis appear more acutely ill than those with toxic synovitis (Luhmann et al., 2004). The more difficult patients to diagnose are those that present with a history of recent infection, elevation in temperature, and a painful hip with inability to bear weight.