Pediatric Primary Care Case Studies, 1st Ed.

Chapter 32. The Limping Child

Jan Bazner-Chandler

A child with acute onset of a limp presents a diagnostic problem of some complexity and urgency that requires an efficient and structured sequence of diagnosis and treatment. The etiology can be infection, genetic, developmental disorders, physical injury, neoplastic, hematologic, or vascular. This case study explores the presenting symptoms and signs of this condition and will review the workup and treatment of the underlying causes.

Educational Objectives

1.  Define normal gait development as related to developmental age.

2.  Apply guidelines for the diagnosis of the child with a limp, taking into consideration the chronological and developmental age of the child.

3.  Consider the differential diagnoses of a limp of acute onset.

4.  Choose appropriate diagnostic testing and treatment options.

5.  Describe desirable outcomes as a function of disease state.

6.  Describe treatment, follow-up, and compliance with medical management.

  Case Presentation and Discussion

Tyler, a 4-year-old African American male, presents to the clinic with a 2-day history of a limp and now refuses to bear weight. His mother states he felt abnormally warm last night when she put him to bed but she did not take his temperature. Today he has been less active than usual, and his appetite has been poor. He is the youngest of three boys and is usually quite active.

What additional history do you want to collect as the healthcare provider? image

The healthcare provider must get additional information regarding chief complaint, history of present illness, past medical history, family, and social history in order to make the diagnosis and begin treatment. In this particular case, you will need more information about the following:

•  Characteristics of pain: Degree of pain using FACES pain tool, pattern (Is there any time of day when the limp is worse? Has the limp or pain interfered with normal activity? Is there any weakness in the extremity?), location, and quality.

•  Activities: Has there been any trauma, injuries, or potential for child abuse?

•  Recent infections or exposure to infections: Family and other contacts.

•  Constitutional signs or symptoms: Weight loss, change in eating or sleep patterns, irritability.

•  Birth, immunization, nutritional, and developmental history: Any pregnancy, labor, or delivery problems; immunizations to date; details about whether speech and language, personal, social, and fine and gross motor skills are developmentally appropriate for his age based on results of developmental screening.

•  Family medical history: Stature, cancer, arthritis, inflammatory or sickle cell disease.

•  Socialization: Day care, babysitter, family members.

•  Medications: Prescription and over the counter.

•  Environment: Lead exposure.

History of Present Illness, Family and Social History

Here is what was revealed in the analysis of the symptoms and the family and social history:

The mother states that Tyler was born full term via a normal spontaneous vaginal delivery. Developmentally he has reached all of his milestones. His immunizations are up-to-date by record review. He has no known allergies. The mother states she took him to the emergency department for a fever, earache, watery eyes, and a cough 1 month ago. He was diagnosed as having an ear infection and a viral upper respiratory infection. His treatment consisted of an antibiotic and cough syrup. He had two doses of acetaminophen for fever after the emergency room visit but none since. Currently there are no immediate family members who are sick with infectious diseases. There was no known trauma. An uncle has the sickle cell trait but Tyler has tested negative for the trait. A grandmother has type 2 diabetes, hypertension, and arthritis.

Physical Examination

What information do you want to collect from the physical examination? image

It is important to examine the child to identify the anatomic location of the pain. The examiner must determine what body segment is creating the problem. Observation will reveal body habitus such as preference for supine, side lying, or prone position. Immobility or pseudoparalysis is an indicator of pain. Hip flexion and external rotation are positions of relative comfort for a painful hip, as is flexion of the knee. The presence of guarding (resistance to motion with gentle passive movement) can indicate the location of the pain. Range of motion of each body segment should be measured along with circumference and length of each body segment in the lower extremities. Asymmetry of the thighs or legs may suggest a chronic condition. The examiner should obtain and record vital signs, perform a vascular examination, and determine if erythema or edema is present.

The essential features of the examination of the extremities are inspection, palpation, and range of motion testing. It is important to inspect the extremities for evidence of deformity, erythema, swelling, effusion, and asymmetry. Palpate for edema, pulses, and manifestations of tenderness or guarding. Examine each joint for range of motion and note any restrictions. The child should be placed prone if possible, with the knees flexed; rotate the hip in and out to check for asymmetry. Examine the child’s shoes for wear patterns and fit. Observe the pattern of walking. In the ambulatory older infant, toddler, or small child, have the child walk back to the caretaker while you observe their gait. In the toddler or small child, the use of distraction can often get the child to cooperate. A child with an inflammation of the hip will keep the hip in a position of flexion, abduction, and external rotation because this position reduces pressure from increased fluid within the joint capsule. In the presence of bacterial infection, any motion is exquisitely painful. The examiner should be aware that developmental dysplasia can cause asymmetric abduction without severe pain. A modified log roll test may help to determine the severity of hip irritation. The child lies supine and the examiner gently rotates the involved limbs from side to side.

Tyler’s physical examination reveals the following: temperature 37.6°C (99.7°F), heart rate 124, respiratory rate 36, blood pressure 115/76, and weight 24 kg (52 lbs 12 ozs).

General appearance: The child is lying across his mother’s lap, immobile but alert and responsive. His skin shows no erythema or rashes.

Neurological: Deep tendon reflexes on the right are 2+ and not determinable on the left due to pain.

Orthopedic:

image  No abnormal curvature of the spine; no hair tufts or dimples are noted.

image  When asked to locate his pain, he points to the groin and upper thigh.

image  All upper extremity joints have full range of motion with no swelling, erythema, or pain with palpation.

image  His right ankle, knee, and hip have unrestricted pain-free motion.

image  His left hip is held flexed, abducted, and externally rotated.

image  He has guarding and begins to cry and pushes your hand away when you attempt to move the left hip.

image  His left knee and ankle are nontender and have no swelling or erythema.

image  His leg and thigh measurements are circumferentially equal.

image  His leg lengths are equal.

The examiner must also take into account the normal gait of young children. Characteristics of childhood gaits are found in Table 32-1. Because Tyler will not walk, you cannot assess his gait today.

Table 32–1 Gait According to Chronologic Age

Age

Description of Gait

 

10–12 months

Cruises while holding onto objects

12–14 months

Walks short distances and stands unaided

17–21 months

Balances on one foot long enough to walk up steps

30–36 months

Balances on one foot for more than a second

36 months

Develops sufficient balance to attain a normal gait pattern

Differential Diagnosis

A limp is defined as any deviation from a normal gait pattern for the child’s age. An antalgic limp is caused by pain and is remarkable because the amount of time the patient spends with his or her body supported by the involved extremity is reduced. In contrast, a short leg limp caused by a leg length difference results in a gait in which equal time is spent on both legs. A chronic limp of weeks to months is typically associated with atrophy of the thigh and calf as well. The inability of young children to clearly describe the location and nature of their pain contributes to the diagnostic challenge.

Common causes for antalgic limp are conditions that cause hip pain such as trauma or inflammation. Inflammation, in turn, can be caused by infection, arthritis, neoplasia, and vasculitis. The causes of limp in the pediatric population can be further sorted by age.

For a 4-year-old, the most relevant considerations are:

•  Trauma

•  Infection

image  Bacterial infection of the hip joint

image  Osteomyelitis of the femur or acetabulum

image  Postviral synovitis (toxic synovitis)

•  Developmental

image  Congenital hip dysplasia (CHD)

image  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? image

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? image

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.

Is the condition emergent? image

The most important part of the diagnosis is to ensure that the hip pain is not caused by a bacterial infection of the hip joint. Early, accurate diagnosis of septic arthritis of the hip in children is critical because poor outcomes have been associated with a delay in diagnosis (Kocher, Mandiga, Zurkowski, Barnewold, & Kasser, 2004). Differentiating between septic arthritis and transient synovitis of the hip can be difficult.

Management

Tyler has a history of febrile illness in the past month and treatment with antibiotics for otitis media (OM) and upper respiratory infection (URI). The physical examination is positive for a painful left hip with pain on movement. Given the history and positive physical findings, an anteroposterior and lateral X-ray and laboratory tests including CBC with differential, ESR, and CRP would be indicated. The physiologic response to an early bacterial infection can be variable and can result in serum makers (elevated ESR, WBC, and CRP) of inflammation within the normal range of values (Luhmann et al., 2004). If the laboratory values indicate septic arthritis, an ultrasound with hip aspiration would be indicated.

Medical management differs depending on the diagnosis. In transient synovitis, bed rest, non-weight-bearing activity, and nonsteroidal anti-inflammatory drugs are the standard treatment recommendations. In septic arthritis, the child would need to be managed by an orthopedic surgeon and requires immediate surgical intervention and intravenous antibiotics.

Test Results

After reviewing Tyler’s hip X-rays and laboratory values, you make the diagnosis of transient synovitis. The sedimentation rate is 6 mm/hr, C-reactive protein is 0.3 mg/L, and WBC count is 10,000/mm3.

Kocher and associates (2004) developed a clinical prediction algorithm for septic arthritis based on four clinical variables: history of fever, non-weight-bearing, an erythrocyte sedimentation rate of greater than or equal to 40 mm/hr, and serum white blood-cell count greater than 12,000/mm3. When all four variables are present the child has a 99.6% chance of having septic arthritis of the hip (Kocher et al., 2004). C-reactive protein level was added as an important part of the evaluation due to its elevation within 6 to 8 hours after onset of inflammatory process or infection. A C-reactive level of > 2.0 mg/dL is considered positive (Caird et al., 2006). Fever was defined as an oral temperature of 38.5°C (101.3°F) or greater during the week prior to admission (Luhmann et al., 2004).

Plain radiographs of the hip are useful in detecting other causes of hip pain; however, they are not sensitive enough to exclude the diagnosis of septic arthritis (Shah, 2005). An ultrasound of the hip is more sensitive than the plain film in identifying joint effusions of the hip. An ultrasound does not assist in determining the cause and is best used to guide hip aspiration. Diagnostic synovial fluid aspiration remains the gold standard for excluding septic arthritis of the hip (Shah). Specific etiologic agents can be identified through blood, bone, or joint aspirate cultures.

Educational plan: What does the mother need to know about transient synovitis and its management? image

Transient synovitis is a benign disease, so treatment consists of supportive therapy. The major goal of therapy is to provide comfort and reduce activity until the inflammation subsides (Whitelaw & Schikler, 2008).

The treatment plan for Tyler will be:

image  Bed rest or position of comfort for 7–10 days.

image  Do not bear weight on affected limb.

image  Avoid full unrestricted activity until limp and pain have resolved.

image  In a 4-year-old, bed rest for any period of time may be difficult. Position the child on a couch or chair so he or she can observe family activity. Encourage sedentary activities with the help of siblings, such as board games, puzzles, or video games.

image  Provide ibuprofen 10 mg/kg per dose given every 6 to 8 hours. The parent may administer it with food or milk to decrease GI upset.

image  Return in 24 hours for repeat exam.

image  Call if the child has high fever or symptoms worsen.

What medications will provide the best pain relief? image

Naproxen and ibuprofen are the most frequently prescribed nonsteroidal anti-inflammatory drugs (NSAIDs) used for children. NSAIDs may shorten the duration of symptoms (Whitelaw & Schikler, 2008). In a randomized clinical trial, ibuprofen was found to shorten the duration of symptoms in cases of mild transient synovitis of the hip (Kocher, 2004). In cases of severe transient synovitis, medications such as ibuprofen or acetaminophen may need to be avoided so that symptoms of septic arthritis will not be masked (Kocher). The most important factor in the drug therapy is to make sure the parent/caretaker is giving the medication in the correct dose at the prescribed intervals. NSAIDs should be administered with food to avoid gastrointestinal upset. The parent/caretaker needs to understand that they are giving the medication for the anti-inflammatory effects so the medication needs to be given around the clock, not just when the child has pain or fever.

When do you want to see this child back? image

Diagnosis of an infected hip is especially difficult in the early phase. The physiologic response to early bacterial infection is quite variable, and serum indicators of inflammation can be within normal range (Luhmann et al., 2004). Follow-up in 12 to 24 hours is crucial to check for changes in the child’s condition.

24-Hour Follow-Up

Tyler is seen in the clinic the next morning. According to his mother he has been afebrile and slept through the night. She has given him the prescribed ibuprofen every 6 hours. He is sitting on his mother’s lap looking at a picture book. When he is examined he still has some hip irritability and guarding, but is more cooperative than on the previous exam. An appointment is made to return to the clinic in 1 week with instructions to call if the child develops fever or increased pain. The mother is instructed to continue administering the ibuprofen for inflammation until the next visit.

One week later Tyler is seen in the clinic. He is sitting on the floor playing with a truck. His mother states it has been difficult to keep him from running around and playing with his brothers. He has been afebrile. On examination he has no complaints of pain or guarding, with range of motion of the hip. He is able to ambulate without a limp. At this time, you instruct the mother to discontinue the ibuprofen and to let him resume his normal activity. She is to return to the clinic if he becomes febrile or has hip pain.

Tyler’s mother asks you if there are any long-term effects that she should watch for.

How will you answer her question? image

The parent should be informed about the following expected outcomes:

image  Transient synovitis requires systematic treatment and typically resolves without complication (Shah, 2005).

image  Patients with transient synovitis usually experience marked improvement in 24–48 hours.

image  Two thirds to three fourths of patients usually experience complete resolution in 2 weeks.

image  The recurrence rate is 4–17%; most recurrences develop within 6 months.

image  There is no increased risk for chronic juvenile arthritis.

image  There is a slightly increased risk for developing osteoarthritis later in life (Whitelaw & Schikler, 2008).

Key Points from the Case

1. History with an analysis of the presenting symptoms and a physical exam are key to making the proper diagnosis.

2. Review of the causes of acute limping in the child identifies the differential diagnosis that must be considered.

3. Know the key radiographs and laboratory values that are needed to make the correct diagnosis.

4. Management and follow-up care of toxic synovitis are critical points to discuss with the parents.

REFERENCES

Adler, B. (2008). Slipped capital femoral epiphysis. Retrieved June 2, 2009, from http://emedicine.medscape.com/article/413810-overview

Beach, C. B., & Ficke, J. (2007). Limping child. Retrieved June 2, 2009, from http://emedicine.medscape.com/article/1258835-overview

Caird, M., Flynn, J. M., Leung, L., Millman, J., D’Italia, J., & Dormans, J. (2006). Factors distinguishing septic arthritis from transient synovitis of the hip in children. A prospective study. Journal of Bone and Joint Surgery, 88(6), 1251–1257.

Fordham, G., Gunderman, R., Blatt, E. R., Bulas., D., Coley, B. D., Poderberesky, D., et al. (2007). American College of Radiology ACR appropriateness criteria: limping child: ages 0–5 years American College of Radiology. Retrieved June 2, 2009, from http://www.guideline.gov/summary/summary.aspx?ss=15&doc_id=11598&nbr=6011

Junnila, J., & Cartwright, V. (2006a). Chronic musculoskeletal pain in children: part I. Initial evaluation. American Family Physician, 74(1), 115–122.

Junnila, J., & Cartwright, V. (2006b). Chronic musculoskeletal pain in children: part II. Rheumatic causes. American Family Physician, 74(2), 293–300.

Kocher, M. (2004). Ibuprofen shortened time to symptom resolution in children with transient synovitis of the hip. Journal of Bone and Joint Surgery, 86(2), 439.

Kocher, M., Mandiga, R., Zurkowski, D., Barnewold, C., & Kasser, J. (2004). Validation of a clinical prediction rule for the differentiation between septic arthritis and transient synovitis of the hip in children. Journal of Bone and Joint Surgery, 86(8), 1629–1635.

Luhmann, S., Jones, A., Schootman, M., Gordon, J. E., Schoenecker, P., & Luhmann, J. (2004). Differentiation between septic arthritis and transient synovitis of the hip in children with clinical predictive algorithms. Journal of Bone and Joint Surgery, 86(5), 956–962.

Mace, S. (2006). Legg-Calve-Perthes disease: an update. Resident and Staff Physician, 52(7). Retrieved June 2, 2009, from http://www.residentandstaff.com/issues/articles/2006-07_07.asp

Neumayer, L. D., Auilar, C., Earles, A. N., Jergensen, H. E., Haberkern, C. M., Kammes, B., et al. (2006). Physical therapy alone compared with core decompression and physical therapy for femoral head osteonecrosis in sickle cell disease. Results of a multicenter study at a mean of three years after treatment. Journal of Bone and Joint Surgery, 88(12), 2573–2582.

Shah, S. S. (2005). Abnormal gait in a child with fever. Diagnosing septic arthritis of the hip. Pediatric Emergency Care, 21(5), 336–341.

Storer, S. K., & Skaggs, D. (2006). Developmental dysplasia of the hip. American Family Physician, 74(8), 1310–1316.

Whitelaw, C., & Schikler, K. (2008). Transient synovitis. Retrieved April 27, 2009, from http://emedicine.medscape.com/article/1007186-overview