Bacterial Prepatellar Bursitis

A 55-year-old, previously healthy man had a 2-day history of acute knee pain. Swelling was visible over the patella, and fluctuation was felt on palpation, suggesting prepatellar bursitis. The skin over the knee was warm and mildly reddened. The patient had no fever. After clinical examination, it could be observed with ultrasound how liquid could be gathered by squeezing into a thicker layer in the centre of the bursa. An appropriate puncture location was evaluated after which the skin was cleansed with chlorhexidine.

The needle is inserted perpendicularly into the bursa, while the bursa is grasped with a ring-shaped grip to press the fluid into the centre of the bursa. To minimize the pain and to reduce the risk of bacterial contamination, it is recommended to perform the puncture from the side, through healthy skin. The puncture site is covered with a self-adhesive sterile dressing, and it should not be allowed to get wet on the puncture day.

The bursa fluid leukocyte count was only 1600/cubic millilitre, and the majority were polymorphonuclear. Staphylococcus aureus was, however, cultured from the fluid. Serum CRP was 43 mg/dl. The patient was treated with intravenous cefuroxime for the first 24 hours, followed by peroral cephalexine.

If bacterial bursitis is suspected on clinical grounds, antibiotics should be started without waiting for bacterial culture results. Even a slightly increased leukocyte count in the bursal fluid supports the diagnosis of bacterial bursitis. In aseptic bursitis the cell count is very low (often below 300). See article Investigation of synovial fluid Investigation of Synovial Fluid

Bacterial Prepatellar Bursitis

Bacterial prepatellar bursitis