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A bursa is a cellular membrane overlying bony prominences (eg, prepatellar bursa or olecranon).1 Bursitis is inflammation in the bursa of the knee or elbow, with septic or non-septic origin. Acute accidental trauma can lead to an infected bursa2 whereas non-septic causes include Osgood-Schlatter disease, juvenile rheumatoid arthritis and sports-related trauma.2 It is important to differentiate septic bursitis from arthritis and osteomyelitis in terms of severe bacterial infection. Paediatric septic bursitis, however, is extremely rare, and therefore the diagnosis can be challenging.
An 8-year-old boy without any medical history visited the emergency department with right knee pain for 2 days and fever for 1 day. He denied any trauma prior to the consultation. On admission, his temperature was 38.2°C, heart rate was 110 beats/min, respiratory rate was 20 and oxygen saturation was 100% on room air. Physical examination showed tenderness, swelling and mild redness on the front of the knee, and difficulty in gait. There were no abnormal eczematous skin lesions or abnormalities of the knee joint, and the range of motion was intact. Blood test showed that white cell count (WCC) was 11×109/L and C-reactive protein 0.08 mg/dL. X-ray film of the knee showed no abnormality. Although synovial fluid was not aspirated by knee puncture, bursal fluid was purulent (WCC 123×109/L). As Gram stain revealed Gram-positive Staphylococci, cefazolin was administrated. MRI of the knee showed no significant abnormalities in the joint space, but there was accumulation of fluid in the prepatellar bursa (figure 1A–C). Methicillin-susceptible Staphylococcus aureus was detected in the synovial fluid culture, confirming the diagnosis of septic bursitis. Blood culture on admission was negative. Fever reduced on the third day of hospitalisation and local findings also improved. He received cefazolin for 12 days followed by cephalexin for 2 days. No recurrence was observed after 1 year.
In this case, MRI helped in early definitive diagnosis, excluding arthritis or osteomyelitis. The duration of treatment for septic bursitis, septic arthritis and osteomyelitis is different. Uncomplicated septic bursitis requires oral treatment,3 whereas some cases may require several rounds of drainage or bursectomy.1 Furthermore, if treatment is not correct, septic bursitis may result in osteomyelitis that can lead to further bony destruction.1 Therefore, early diagnosis with correct examination, prompt Gram staining and MRI imaging, and early treatment are essential in the management of septic bursitis.
Bursitis is inflammation in the bursa of the knee or elbow, with septic or non-septic origin.
Paediatric septic bursitis is extremely rare, and the diagnosis can be challenging.
MRI is useful to differentiate septic bursitis from septic arthritis and osteomyelitis.
Contributors AI managed the patient, drafted the initial manuscript and approved the final manuscript prior to submission. YA critically reviewed and revised the manuscript and approved the final manuscript prior to submission. KK revised the manuscript and approved the final manuscript prior to submission.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.
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