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How To Aspirate or Inject a Prepatellar Bursa

By

Alexandra Villa-Forte

, MD, MPH, Cleveland Clinic

Last full review/revision Oct 2020| Content last modified Oct 2020
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Prepatellar bursal puncture is done to aspirate effusions and sometimes inject anesthetics, sometimes with corticosteroids, to help diagnose and/or treat prepatellar bursitis.

The prepatellar bursa lies just below the skin, increasing the risk of skin damage and infection from corticosteroid injection therapy.

Prepatellar bursitis typically manifests with obvious swelling and erythema; thus, ultrasonography for evaluation and needle guidance is usually unnecessary.

Indications

  • Aspiration of effusion to determine cause of bursitis

  • Rarely for injections of corticosteroid to treat inflammation

Prepatellar bursal puncture is usually done diagnostically (eg, to diagnose septic or crystal-induced bursitis). Because the prepatellar bursa is the second most common site of septic bursitis, effusion fluid should be sent to the laboratory for cell count, Gram stain, culture, and sensitivity tests.

Corticosteroid injection is rarely necessary in the prepatellar bursa. Therapeutic injection should be done only if all of the following criteria are satisfied:

  • Infection has been excluded by bursal fluid analysis.

  • Bursal fluid reaccumulates.

  • Symptoms are not relieved by local measures such as ice, elevation, elastic bandage, and nonsteroidal and anti-inflammatory drugs.

When needed, bursal injection therapy provides rapid relief, which is particularly beneficial for large or painful effusions.

Contraindications

Absolute contraindications

  • Overlying cellulitis or skin ulcer, bacteremia, adjacent acute fracture or osteomyelitis, osteochondral fracture

  • Hypersensitivity to an injected substance

  • For corticosteroid injection, suspected septic bursitis

Relative contraindications

  • Poorly controlled diabetes: Any benefit of corticosteroids is weighed against risk of worsening glycemic control.

  • Previous corticosteroid injection into same site: Many experts advise waiting 3 to 4 months between injections and not exceeding a lifetime total of 4 injections.

Complications

Complications are uncommon and include

  • Subcutaneous fat atrophy, skin atrophy and sinus tracts, temporary skin depigmentation, and infection due to superficial (< 0.5 cm deep) corticosteroid injection

  • Painful local reaction (sometimes called steroid flare) occurring within a few hours of depot corticosteroid injection and usually lasting ≤ 48 hours (probably irritation due to crystals in the injection vehicle)

  • In diabetic patients, hyperglycemia that may persist for weeks after a depot corticosteroid injection

Equipment

  • Antiseptic solution (eg, chlorhexidine, povidone iodine, isopropyl alcohol)

  • Sterile drapes

  • Sterile gauze, sterile gloves, sterile adhesive bandage

  • 20-mL syringe with 18- to 20-gauge needle for fluid withdrawal

  • Needle insertion site anesthesia (eg, topical freezing spray and/or injectable 1% lidocaine without epinephrine, in a 3-mL syringe)

  • Optional: For therapeutic injection, 5- to 10-mL syringe with 2 to 3 mL 1% lidocaine without epinephrine, rarely with injectable depot corticosteroid (eg, methylprednisolone acetate, 20 mg)

  • Hemostat

  • Some 3-, 5-, and 20-mL syringes with nonlocking hubs

  • For diagnostic aspiration, appropriate tubes for specimen collection, including blood culture bottles

Having an assistant is helpful.

Additional Considerations

  • For bursal injection therapy, local anesthetic and depot corticosteroid can be mixed in a single syringe (the anesthetic eliminates the pain of the corticosteroid).

  • Corticosteroid injection is rarely necessary in the prepatellar bursa.

  • Septic bursitis cannot be ruled out by the initial gross and microscopic examination of the aspirated effusion. Infected fluids (even from Staphylococcus aureus, the most common organism) tend to show a minimal fluid leukocytosis.

    If the history or physical examination suggests septic bursitis, withhold bursal corticosteroid injection. Septic bursitis requires drainage or sometimes bursal excision in addition to systemic antibiotics.

  • Immediate analgesia after injection of local anesthetic helps confirm correct needle placement and that the prepatellar bursa is the source of pain.

Relevant Anatomy

  • Fluid in the prepatellar bursa is often loculated, resulting in less fluid accessible for withdrawal than expected.

Positioning

  • Position the patient reclined or supine. Comfortably rest the knee, slightly flexed, on a pillow.

  • To avoid vasovagal episodes, avert the patient's head and orient your work area so that the patient does not see the needles.

Step-by-Step Description of Procedure

Do the procedure using sterile technique.

Prepare the site

  • Identify the bursa's point of maximum fullness and mark it on the skin for needle entry.

  • Prepare the area with antiseptic solution.

  • Apply sterile drapes that widely expose the needle insertion site and the patella.

  • Spray freezing spray at the needle insertion site until it just blanches and/or inject a skin wheal of local anesthetic (eg, ≤ 1 mL).

Puncture the bursa

Aftercare

  • A protective compression bandage may prevent reaccumulation of fluid in traumatic bursitis.

  • Prescribe limited activity, ice, elevation, and oral nonsteroidal anti-inflammatory drugs (NSAIDs) until pain subsides.

  • Instruct the patient to return for reassessment to exclude infection if pain is continuously and progressively increasing after several hours or persists for > 48 hours.

Warnings and Common Errors

  • Do not inject corticosteroids against resistance; if there is resistance, slightly withdraw the needle.

Tips and Tricks

  • Consider doing ultrasonography if there is no obvious large effusion.

  • When inspecting bursal fluid, consider the following: The blood due to a traumatic needle insertion tends to be nonuniformly bloody and tends to clot.

Reference

  • 1. Yui JC, Preskill C, Greenlund LS: Arthrocentesis and joint injection in patients receiving direct oral anticoagulants. Mayo Clin Proc 92(8):1223–1226, 2017. doi: 10.1016/j.mayocp.2017.04.007

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