1. Garcia, Mayra G. MSN, RN, PCNS-BC

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Susie is a previously healthy 7-year-oldWhite female who presented to the emergency department with right knee pain for 3 days. Susie denied any injuries to the right knee but was unable to bear weight for the last 3 days. Her mother reported a high fever of 101.1[degrees]F last night at home. Other than right knee, Susie's mother denied any recent illnesses or exposure to sick contacts in the last 2 weeks.



Upon examination, the advanced practice provider found decreased range of motion, moderate redness and swelling, and an irritable right knee joint (pain preventing free movement). No abrasions or bruising was noted. There was no focal tenderness over the distal femur. Susie's vital signs read as follows: heart rate of 121, respiratory rate of 28, temperature of 101.5[degrees]F, and blood pressure of 108/68. The advanced practice provider ordered ibuprofen (10 mg/kg) to treat pain and fever as well as laboratory testing (Table 1) and a radiology examination to the right knee.

Table 1 - Click to enlarge in new windowTable 1 Laboratory and Radiology Findings


What are some possible differential diagnoses for Susie?


A. Distal femur fracture


B. Septic arthritis


C. Prepatellar bursitis


D. Distal femur osteomyelitis




B. Septic arthritis



The advanced practice provider reviews the results (Table 1) of the laboratory findings and radiology examination to make a diagnosis. Reviewing the results of the radiology examination can rule out the diagnosis of distal femur fracture. Susie's history is negative for any trauma, and the radiology examination is negative for any fractures. Patients with typical prepatellar bursitis do not commonly see joint involvement such as an irritable knee joint; therefore, the advanced practice provider can also exclude prepatellar bursitis as a differential diagnosis. Lack of focal tenderness over the distal femur can rule out the diagnosis of distal femur osteomyelitis. In patients with possible septic arthritis, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) levels are normally elevated. Susie also has moderate redness and swelling to her right knee, decreased range of motion, refusal to bear weight, and knee joint irritability. Although the radiology examination ruled out any likelihood of fracture, it does show a joint effusion. High white blood cell counts and fever can also be an indicator of septic arthritis.


Because of risk of long-term joint damage, septic arthritis is considered an orthopedic emergency. A consult is placed to the pediatric orthopedic service for further management. Susie is promptly admitted to the inpatient surgery unit with a diagnosis of septic arthritis. Her admitting orders include pain control, empiric intravenous antibiotics, intravenous fluids, and a nothing-by-mouth diet order. Susie's diet order, nothing by mouth, is in anticipation for surgery with intravenous fluids to prevent dehydration. Empiric antibiotics are started while awaiting blood and joint culture results. Bedside nurses keep Susie comfortable with fever reducers and pain medication while awaiting her surgical procedure in the morning.



Susie is taken for magnetic resonance imaging in the morning followed by aspiration of the right knee. In the operating room, Susie undergoes an arthrotomy versus arthroscopy with irrigation and debridement. Joint fluid is sent to the laboratory for cell counts and cultures to identify the organism. After recovering in the postanesthesia unit, Susie returns to the surgical floor.


Susie continues on empiric antibiotics, daily blood cultures, and ESR and CRP levels repeated every 48 hours. Blood culture and joint fluid results return and indicate Staphylococcus (S.) aureus. Antibiotic therapy is modified and tailored to treat S. aureus. Once there is an improvement in the clinical examination, antibiotics can be transitioned from intravenous route to oral route. The surgery advanced practice provider will monitor for clinical examination improvement, resolution of fever, and trending down of CRP levels. Consider physical therapy consults and case management assistance in obtaining ambulatory equipment. Susie can meet discharge criteria with clinical improvement, resolution of bacteremia as evidenced by two negative blood cultures, improved range of motion, and tolerating oral antibiotics. Discharge education should include infection warnings and postsurgical site care. Susie is discharged home on 3 weeks of oral antibiotics with follow-up in 1-2 weeks postoperatively.



Prompt evaluation and treatment of patients with associated symptoms of septic arthritis can decrease the mortality and morbidity in pediatric patients. Septic arthritis is an orthopedic emergency that is a bacterial infection of a joint that most commonly affects the knees, hips, elbows, and ankles. Although septic arthritis typically affects a single joint, it can occur in bilateral hip joints. Patients with clinical symptoms of septic arthritis usually present to the emergency department or physician's office with joint pain, swelling, fever, and limited range of motion or limping. Older children may display other features such as nausea, headache, vomiting, or irritability. Elevated CRP levels greater than 2.0, ESR levels greater than 20, and elevated white blood cell counts are also key findings in septic arthritis (Krogstad, 2017). Septic arthritis can occur from trauma to the joint, surrounding cellulitis, or from hematogenous spread to the joint. The most common organism to cause septic arthritis is S. aureus (Agarwal & Aggarwal, 2016).



The author thanks Mary Jones, BSN, RN.




Agarwal A., & Aggarwal A. N. (2016). Bone and joint infections in children: Septic arthritis. Indian Journal of Pediatrics, 83(8), 825-833. doi:10.1007/s12098-015-1816-1 [Context Link]


Hockenberry M., & Wilson D. (Eds.). (2013). Wong's nursing care of infant and children. St. Louis, MO: Mosby Elsevier.


Krogstad P. (2017). Bacterial arthritis: Clinical features and diagnosis in infants and children. In Edwards M. S., Phillips W., Sundel & R. (Eds.), UptoDate. Retrieved from[Context Link]