It generally does not produce a significant amount of pain unless pressure is applied directly. [4] The area may be red ( erythema ), warm to the touch, or surrounded by cellulitis , particularly if infection is present, often accompanied by fever . [5] : p. 608 Unlike arthritis , except in severe cases prepatellar bursitis generally does not affect the range of motion of the knee, though it may cause some discomfort in complete flexion of the joint. [6] : p. 360 Flexion and extension of the knee may be accompanied by crepitus , the audible grating of bones, ligaments, or particles within the excess synovial fluid. [7] : p. 20 Causes [ edit ] In human anatomy , a bursa is a small pouch filled with synovial fluid . ... The trauma can cause extravasation of nearby fluids into the bursa, which stimulates an inflammatory response. [2] This response occurs in two phases: The vascular phase, in which the blood flow to the surrounding area increases, and the cellular phase, in which leukocytes migrate from the blood to the affected area. [7] : p. 22 Other possible causes include gout , sarcoidosis , CREST syndrome , [6] : p. 359 diabetes mellitus , alcohol abuse , uremia , and chronic obstructive pulmonary disease . [7] : p. 22 Some cases are idiopathic , though these may be caused by trauma that the patient does not remember. [5] : pp. 607–8 The prepatellar bursa and the olecranon bursa are the two bursae that are most likely to become infected, or septic . [10] Septic bursitis typically occurs when the trauma to the knee causes an abrasion , though it is also possible for the infection to be caused by bacteria traveling through the blood from a pre-existing infection site. [11] In approximately 80% of septic cases, the infection is caused by Staphylococcus aureus ; other common infections are Streptococcus , Mycobacterium , and Brucella . [6] : p. 359 It is highly unusual for septic bursitis to be caused by anaerobes , fungi , or Gram-negative bacteria . [5] : p. 608 In very rare cases, the infection can be caused by tuberculosis . [12] Diagnosis [ edit ] There are several types of inflammation that can cause knee pain , including sprains , bursitis, and injuries to the meniscus . [9] A diagnosis of prepatellar bursitis can be made based on a physical examination and the presence of risk factors in the person's medical history ; swelling and tenderness at the front of the knee, combined with a profession that requires frequent kneeling, suggest prepatellar bursitis. [2] Swelling of multiple joints along with restricted range of motion may indicate arthritis instead. [5] : p. 608 A physical examination and medical history are generally not enough to distinguish between infectious and non-infectious bursitis; aspiration of the bursal fluid is often required for this, along with a cell culture and Gram stain of the aspirated fluid. [6] : p. 360 Septic prepatellar bursitis may be diagnosed if the fluid is found to have a neutrophil count above 1500 per microliter , [5] : p. 608 a threshold significantly lower than that of septic arthritis (50,000 cells per microliter). [6] : p. 360 A tuberculosis infection can be confirmed using a radiograph of the knee and urinalysis . [12] Prevention [ edit ] It is possible to prevent the onset of prepatellar bursitis, or prevent the symptoms from worsening, by avoiding trauma to the knee or frequent kneeling. [5] : p. 610 Protective knee pads can also help prevent prepatellar bursitis for those whose professions require frequent kneeling and for athletes who play contact sports , such as American football , basketball , and wrestling . [13] Treatment [ edit ] Non-septic prepatellar bursitis can be treated with rest, the application of ice to the affected area, and anti-inflammatory drugs , particularly ibuprofen . Elevation of the affected leg during rest may also expedite the recovery process. [13] Severe cases may require fine-needle aspiration of the bursa fluid, sometimes coupled with cortisone injections. [11] However, some studies have shown that steroid injections may not be an effective treatment option. [14] After the bursitis has been treated, rehabilitative exercise may help improve joint mechanics and reduce chronic pain . [15] : p. 2320 Opinions vary as to which treatment options are most effective for septic prepatellar bursitis. [6] : p. 360 McAfee and Smith recommend a course of oral antibiotics , usually oxacillin sodium or cephradine , and assert that surgery and drainage are unnecessary. [5] : p. 609 Wilson-MacDonald argues that oral antibiotics are "inadequate", and recommends intravenous antibiotics for managing the infection. [1] Some authors suggest surgical irrigation of the bursa by means of a subcutaneous tube. [6] : p. 360 [16] Others suggest that bursectomy may be necessary for intractable cases; the operation is an outpatient procedure that can be performed in less than half an hour. [17] : p. 357 Epidemiology [ edit ] The various nicknames associated with prepatellar bursitis arise from the fact that it commonly occurs among those individuals whose professions require frequent kneeling , such as carpenters, carpet layers, gardeners, housemaids , mechanics, miners, plumbers, and roofers. [2] [4] [5] : p. 607 The exact incidence of the condition is not known; it is difficult to estimate because only severe septic cases require hospital admission, and mild non-septic cases generally go unreported. [5] : p. 607 Prepatellar bursitis is more common among males than females.
