Prepatellar Bursitis
Swelling and pain over the kneecap, usually caused by frequent kneeling or leaning, which can sometimes become infected.
Emergency Management: Rapidly progressing erythema with systemic sepsis (hypotension, tachycardia) requires immediate IV antibiotics, fluid resuscitation, and emergent surgical I&D.
Inflammation and swelling of the prepatellar bursa, the fluid-filled sac located superficially between the patella (kneecap) and the overlying skin. It can be aseptic (traumatic or inflammatory) or septic (infectious).
Detailed Overview
The prepatellar bursa serves to reduce friction between the skin and the patella during movement. Repeated microtrauma, such as prolonged kneeling, leads to thickening of the synovial lining and excessive fluid production. In acute trauma, bleeding into the bursa causes hemorrhagic bursitis. Abrasions over the knee can allow bacteria (usually Staph aureus) to enter, causing septic bursitis, which requires urgent antibiotics.
Epidemiology & Demographics
Commonly seen in professions requiring frequent kneeling (plumbers, carpet layers, roofers, housemaids, wrestlers). Affects males more than females, generally between the ages of 40 and 60 years.
Etiological Mechanism
Aseptic: Chronic microtrauma (kneeling), acute direct trauma (fall onto the knee), or systemic inflammatory conditions (gout, rheumatoid arthritis). Septic: Direct inoculation of bacteria through a skin breach over the bursa. S. aureus accounts for 80-90% of septic cases.
Primary Causes
["Prolonged kneeling", "Direct blunt trauma to the anterior knee", "Infection via skin abrasion or puncture", "Crystal deposition (monosodium urate in gout)"]
Friction over the bursa causes localized inflammation, leading to vasodilation, increased vascular permeability, and transudation of fluid into the bursal sac. In septic bursitis, bacterial replication induces a severe purulent exudate with intense neutrophilic infiltration, leading to a tense, erythematous, and hot bursa. Because the bursa is superficial to the joint capsule, the knee joint itself is usually unaffected.
Diagnostic Criteria & Guidelines
Clinical diagnosis based on history and physical exam. If septic bursitis is suspected, ultrasound-guided or blind bursal aspiration is mandatory for definitive diagnosis and to rule out septic arthritis. Aspiration fluid must be sent for cell count, Gram stain, culture, and crystals.
Aseptic: RICE therapy (Rest, Ice, Compression wrapping, Elevation). NSAIDs (Ibuprofen 400 mg q6h). Avoid kneeling. Septic (mild/outpatient): Oral antibiotics covering MRSA/MSSA (e.g., Trimethoprim-Sulfamethoxazole DS 1 tab BID or Clindamycin 300 mg QID) for 10-14 days.
Second-Line & Adjunctive Therapy
Septic (severe/inpatient): IV antibiotics (Vancomycin 15-20 mg/kg IV q8-12h). For chronic aseptic bursitis failing conservative management: Aspiration followed by a corticosteroid injection (e.g., 40 mg methylprednisolone) into the bursa. *Never inject steroids if infection is suspected.*
Surgical & Procedural Management
Incision and drainage (I&D) for refractory septic bursitis or if an abscess forms. Open or arthroscopic bursectomy (excision of the entire bursa) for chronic, recurrent, severely thickened aseptic bursitis.
Patient Counseling & Advice
Instruct the patient that the swelling in aseptic bursitis can take weeks to fully resorb. If they return to unprotected kneeling too soon, it will immediately recur.
Follow-Up & Monitoring Schedule
Recheck septic bursitis patients within 48-72 hours to ensure response to antibiotics. Aseptic patients follow up PRN.
Preventive Strategies
Routine use of knee pads for gardeners, roofers, and carpenters. Prompt cleansing of any cuts or scrapes over the knee with soap and water.
Excellent. Most aseptic cases resolve with conservative care. Septic bursitis cures completely with appropriate antibiotics, though severe cases may require surgery.