Prepatellar Bursitis
Also known as housemaid's knee, prepatellar bursitis is usually caused by repeated microtrauma associated with kneeling, but it can in rare circumstances be caused by an infection. Ask patients who present with atraumatic anterior knee pain accompanied by swelling and redness whether they spend much time scrubbing floors, gardening, laying carpet, or performing other activities that involve excessive kneeling or wearing hard knee pads.
A patient with an infected prepatellar bursa may present with fever, chills, and sweatiness. On physical exam, the area will be warm and tender to the touch, but that isn't enough to confirm or rule out sepsis. Get a cell count and gram stain to rule out infection. White blood cell counts are usually greater than 10,000 cells/mcL in septic patients but less than 1,000 cells/mcL in nonseptic patients.
As for treatment, Dr. Flinn recommends treating for gram-positive Staphylococcus aureus, which is the cause of 80% of these infections. Methicillin-resistant S. aureus (MRSA), Mycobacterium tuberculosis, and M. marinum are rare causes. Treatment should be based on cultures, whenever possible.
Prescribe ice packs and NSAIDs for nonseptic patients, and recommend a knee pad for protection in nonacute cases. Rehab for nonseptic patients is similar to strategies for other atraumatic anterior knee injuries and is based on the PRICEMM principles (see box). Focus on stretching and strengthening the quadriceps, hamstrings, and iliotibial band, and recommend the use of a cushioned knee pad, perhaps with a hard exterior shell, when the patient resumes activity.
A Twist on RICE For Management
In all cases of atraumatic knee pain, remember the principles of PRICEMM (an extension of the old standby RICE):
▸ Protect the injury from additional harm (with bracing, for example)
▸ Relative rest (maintain cardiovascular and strength training activities in other ways)
▸ Ice
▸ Compression
▸ Elevation
▸ Medications (NSAIDs for pain)
▸ Modalities for rehab (stretching, physical therapy)