Prepatellar Septic Bursitis in an 11 year old Girl

Background: Prepatellar bursitis is an inflammation and fluid collection within the prepatellar bursa, typically due to trauma and less frequently related to infection, leading to septic bursitis. It is an extremely rare condition in the pediatric population.

Case Report: An 11-year-old obese girl presented to the emergency department reporting fever and an erythematous, swollen, and painful right knee following a trauma four days earlier. Two days before, she had been evaluated by an orthopedist who diagnosed a post-traumatic prepatellar bursitis. On admission she had normal vital signs, difficulty in gait and a knee with signs of inflammation and tender to palpation. There were insect bites in the skin overlying the area. Blood tests revealed: white cell count 13,6x10⁹/L, neutrophils 66,3%, sedimentation rate 52mm/h and C-reactive protein 17,2mg/dL. There were an increased volume of the soft tissue anterior to the patella at the x-ray. She was hospitalized and 24 hours later spontaneously drained purulent and serohematic content through a blister with 7 cm in diameter and the wound was cleaned. The ultrasonography showed a superficial abscess with a fistula to the exterior, with no intra-articular extension. The culture of bursal fluid revealed a methicillin-susceptible Staphylococcus aureus. She completed 7 days of endovenous flucloxacillin at the hospital and another 7 days orally at home. She had a favorable evolution, with no long-term complications.

Conclusion: If not treated correctly, septic bursitis can result in osteomyelitis with bone destruction. Early diagnosis with Gram staining and imaging is essential both to provide early adequate treatment and to exclude joint or bone involvement.