Approach Considerations
Usually, laboratory studies are necessary only if the clinician suspects that an underlying condition is present. If an infection is suspected, the olecranon bursa should be aspirated as outlined below. Lab work, including a complete blood count (CBC) with differential, serum C-reactive protein, erythrocyte sedimentation rate, and glucose, should be obtained. The literature has indicated that a ratio of bursal fluid glucose concentration to serum glucose concentration of less than 50% is diagnostic of a septic bursitis; however, some studies refute this finding, stating that this comparison has a false-negative rate of 9%. [23] If there is concern for rheumatoid arthritis or gout, tests should include a rheumatoid factor and uric acid level, respectively.
Gram Stain
If infection is suspected (due to the presence of fever, erythema, previous puncture wounds, or cellulitis), the olecranon bursa should be aspirated and the fluid sent for culture, a cell count (WBCs, RBCs), and immediate Gram staining for bacteria. If the Gram stain is positive for bacteria, antibiotics should be started immediately and no corticosteroids should be injected into the bursa.
However, even if the Gram stain is negative or initially unavailable, withholding corticosteroid injection and starting antibiotics may seem indicated based on the mechanism of injury (eg, abrasion or puncture), physical examination findings suggestive of infection (eg, fever, significant local erythema and warmth), or the overall appearance of the aspirate (eg, turbid, purulent).
WBC Count and Bacterial Culture
WBC count
The leukocyte count can help to determine whether the fluid is infectious or merely inflammatory. [24] Within synovial aspirates, WBC counts are assessed as follows:
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Less than 200/µL - Normal
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200-2000/µL - Noninflammatory
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2000-100,000/µL - Indicative of an inflammatory etiology
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>100,000/µL - Indicative of a septic etiology
Bacterial culture
Bacterial culture and sensitivity testing of the aspirate can be performed to ensure that the relevant bacteria are sensitive to the chosen antibiotic. These results can guide the modification of antibiotics in cases of bacterial infection. The most common organism cultured is the gram-positive coccus penicillinase-producing Staphylococcus aureus. [23, 25]
Other findings
After an acute injury, blood may be found within the aspirate, indicating a hemorrhagic bursitis (see the image below).
Aspiration of a hemorrhagic effusion in a patient with olecranon bursitis. Image courtesy of UMDNJ-New Jersey Medical School, www.DoctorFoye.com, and www.TailboneDoctor.com.
Analysis for crystals may reveal monosodium urate crystals in patients with gout, calcium pyrophosphate crystals in pseudogout, or hydroxyapatite crystals (see the image below).
Imaging Studies
Radiography
Plain film radiographs of the elbow should be performed to assess for a possible olecranon fracture if significant trauma occurred or if an avulsed osteophyte is present at the triceps insertion into the olecranon, which is fairly common. (See the image below.)
Ultrasonography
The use of ultrasonography has been shown to be extremely effective in the diagnosis of olecranon bursitis and other soft-tissue lesions in the olecranon area by rapidly demonstrating the presence of effusions, synovial proliferation, loose bodies, increased blood flow consistent with inflammation, tendonitis with calcifications, and other indications of bursitis. [8]
Magnetic resonance imaging
In atypical cases, an MRI study may be indicated to help exclude concomitant pathology, such as a stress fracture, triceps tendinopathy versus tear, or the rare case of osteomyelitis/abscess or tumor, especially if there is a long history of septic bursitis. This form of imaging is also helpful in the evaluation of an unusual mass seen on plain radiographs. [9]
Bursal Aspiration
The olecranon bursa can be aspirated using a long 18-gauge needle that is inserted after sterile skin preparation, using a circular motion with an antibacterial solution (after determining no applicable allergies exist) and appropriate local infiltration with a suitable agent, such as 1% lidocaine, using sterile technique to avoid secondary infection and a 27- to 30-gauge needle to make a skin wheal over the lateral bursa. The 18-gauge needle is attached to a 10-mL syringe and inserted into the dependent area of the bursa through a posterolateral approach, via an oblique needle angle or zigzag approach. [26]
As opposed to a direct, perpendicular approach that is used for most joint aspirations, this technique creates a longer needle tract through the skin and subcutaneous layers, thus minimizing the risk of fistula formation. The medial approach to the olecranon bursa should be avoided, since a misdirected needle could damage the ulnar nerve. Aspiration of bursal contents is continued until the bursal site is flat. The needle is then withdrawn and the wound dressed with adhesive sterile bandage and the elbow wrapped with a compressive dressing. Active elbow range of motion should be restricted for about 2 days post injection. (See the images below.) [13, 14, 15]
Olecranon bursogram. This image shows a needle injecting contrast material into the olecranon bursa, under fluoroscopic guidance. Although olecranon bursa aspiration/injection usually does not require fluoroscopy or contrast, employing fluoroscopy here has demonstrated the outline of the involved bursa. Image ©2005, by Patrick M. Foye, MD, UMDNJ: New Jersey Medical School.
Needle aspiration in olecranon bursitis. Image courtesy of UMDNJ-New Jersey Medical School, www.DoctorFoye.com, and www.TailboneDoctor.com.
After fluid is removed from the olecranon bursa, an elastic, tubular compressive sleeve can be used to minimize reaccumulation of the fluid. Image courtesy of UMDNJ-New Jersey Medical School, www.DoctorFoye.com, and www.TailboneDoctor.com.
If cloudy fluid is aspirated, it should be sent for immediate Gram stain, leukocyte count, culture, and antibiotic sensitivity testing. No corticosteroids should be given until these tests prove negative. Aspiration can also be therapeutic, as it relieves the swelling. If cultures of aspirated fluid are negative and fluid recurs, the bursal aspiration can be repeated, and, if sterile on culture, corticosteroids can be considered.
If the clinician is confident that no infection is present, corticosteroid injection can be considered (for instance, immediately after aspiration of the fluid). [27]
In the absence of a traumatic etiology, consideration should be given to analyzing the aspirated fluid for infection and crystals.
When aspiration/injection is performed, aseptic techniques should be used to minimize the chance of causing iatrogenic infection. Septic olecranon bursitis due to Mycobacterium smegmatis has been reported after intrabursal steroid injection. [28]
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Olecranon bursitis, shown here with the elbow flexed. Image courtesy of UMDNJ-New Jersey Medical School, www.DoctorFoye.com, and www.TailboneDoctor.com.
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Olecranon bursitis seen with the elbow extended. Focal swelling at the olecranon is more visible with the elbow extended than in the flexed position. Image courtesy of UMDNJ-New Jersey Medical School, www.DoctorFoye.com, and www.TailboneDoctor.com.
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Olecranon bursitis seen with the elbow extended. Image courtesy of UMDNJ-New Jersey Medical School, www.DoctorFoye.com, and www.TailboneDoctor.com.
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Olecranon bursogram. This image shows a needle injecting contrast material into the olecranon bursa, under fluoroscopic guidance. Although olecranon bursa aspiration/injection usually does not require fluoroscopy or contrast, employing fluoroscopy here has demonstrated the outline of the involved bursa. Image ©2005, by Patrick M. Foye, MD, UMDNJ: New Jersey Medical School.
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Needle aspiration in olecranon bursitis. Image courtesy of UMDNJ-New Jersey Medical School, www.DoctorFoye.com, and www.TailboneDoctor.com.
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Aspiration of a hemorrhagic effusion in a patient with olecranon bursitis. Image courtesy of UMDNJ-New Jersey Medical School, www.DoctorFoye.com, and www.TailboneDoctor.com.
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After fluid is removed from the olecranon bursa, an elastic, tubular compressive sleeve can be used to minimize reaccumulation of the fluid. Image courtesy of UMDNJ-New Jersey Medical School, www.DoctorFoye.com, and www.TailboneDoctor.com.
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Gout. Radiograph of erosions with overhanging edges.
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Gout. Polarizing microscopy revealing needles of urate.
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Rheumatoid arthritis. Rheumatoid nodules at the elbow. Photograph by David Effron MD, FACEP
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Olecranon fracture.
