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.
(See also Bursitis.)
Indications
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:
When needed, bursal injection therapy provides rapid relief, which is particularly beneficial for large or painful effusions.
Contraindications
Complications
Complications are uncommon and include
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Subcutaneous fat atrophy, skin atrophy and sinus tracts, temporary skin depigmentation, and infection due to superficial (< 0.5 cm deep) corticosteroid injection
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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)
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In diabetic patients, hyperglycemia that may persist for weeks after a depot corticosteroid injection
Equipment
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Antiseptic solution (eg, chlorhexidine, povidone iodine, isopropyl alcohol)
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Sterile drapes
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Sterile gauze, sterile gloves, sterile adhesive bandage
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20-mL syringe with 18- to 20-gauge needle for fluid withdrawal
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Needle insertion site anesthesia (eg, topical freezing spray and/or injectable 1% lidocaine without epinephrine, in a 3-mL syringe)
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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)
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Hemostat
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Some 3-, 5-, and 20-mL syringes with nonlocking hubs
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For diagnostic aspiration, appropriate tubes for specimen collection, including blood culture bottles
Having an assistant is helpful.
Additional Considerations
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For bursal injection therapy, local anesthetic and depot corticosteroid can be mixed in a single syringe (the anesthetic eliminates the pain of the corticosteroid).
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Corticosteroid injection is rarely necessary in the prepatellar bursa.
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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.
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Immediate analgesia after injection of local anesthetic helps confirm correct needle placement and that the prepatellar bursa is the source of pain.
Relevant Anatomy
Positioning
Step-by-Step Description of Procedure
Do the procedure using sterile technique.
Prepare the site
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Identify the bursa's point of maximum fullness and mark it on the skin for needle entry.
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Prepare the area with antiseptic solution.
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Apply sterile drapes that widely expose the needle insertion site and the patella.
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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
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Wear sterile gloves.
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Insert the needle (attached to the aspirating syringe) into the skin at the point of maximal fluctuance of the effusion from the lateral side.
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Gently pull back on the plunger as you advance the needle. If the needle hits bone, retract and then readvance it at a different angle.
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Fluid will enter the syringe when the bursa is entered.
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Drain all fluid from the bursa. Use your fingertips to apply gentle pressure to the bursal periphery to milk the fluid toward the needle tip.
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If injecting the bursa, stabilize the needle hub with your hand and switch syringes. If the needle is on too tight, hold the hub of the needle with a hemostat.
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Inject any drugs and withdraw the needle.
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Apply an adhesive bandage or sterile dressing.
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Transfer bursal effusion samples to tubes and other transport media for synovial fluid analysis. Inspect the fluid for blood and fat.
Aftercare
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A protective compression bandage may prevent reaccumulation of fluid in traumatic bursitis.
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Prescribe limited activity, ice, elevation, and oral nonsteroidal anti-inflammatory drugs (NSAIDs) until pain subsides.
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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
Tips and Tricks
Reference
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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
Drugs Mentioned In This Article
| Drug Name | Select Trade |
|---|---|
methylprednisolone |
MEDROL |
epinephrine |
ADRENALIN |
lidocaine |
XYLOCAINE |
