GENERAL ARTHROCENTESIS TECHNIQUE  

In the this section, we will describe the general techniques of arthrocentesis, utilizing the knee joint (the most common site for arthrocentesis, as an example. These techniques are applicable to aspiration of all joints in the human body. In the Specific Joints section you will find further discussion, illustration, and animation of arthrocentesis of specific joints.

 

With proper technique, needle insertion into a joint space is a sterile, minimally traumatic, and relatively painless procedure.

Prepare Patient

 

Prepare Equipment

 

Perform Arthrocentesis

 

Analyze Fluid

Prepare the Patient

Begin by explaining in lay terms to your patient what you are about to do. Explain to your patient that you will be placing a needle into his or her joint. You will collect fluid for analysis to evaluate the cause of swelling and pain. Let your patient know that you will begin by giving them numbing medication to make the procedure as painless as possible. As with any invasive procedure, informed consent must be obtained. The patient should be told that in rare cases, infection, bleeding, and injury to deep structures can occur.

 

Position the patient comfortably with the joint in proper position as outlined in the Specific Joints section of this chapter. All necessary equipment should be within reach, and lighting should be adequate. Universal Precautions should be observed, and a face shield, protective gown and gloves should be worn.

 

As with any procedure, the correct side must be properly identified. If possible, the site should be confirmed by both the patient and another health care worker. The point of entry is marked with the skin marking pen and then initials are placed below this in view for confirmation.

 

Now prepare the area with betadeine using sterile technique. Put on sterile gloves. Using circular movements, begin at the center and work your way outwards. This should be repeated three times. A sterile drape is then positioned over the needle entry site.

 

Next, you will provide local anesthesia to the overlying skin. Always read the label of the anesthetic to confirm that it is the proper medication and concentration. The patient should confirm for you that he/she has no known allergies to the medication. Fill the syringe with lidocaine. The needle is inserted nearly parallel with the skin's surface superficially and a small skin wheal is raised by injection of anesthetic. The needle is removed and then readvanced through the anesthetized skin and an injection of anesthetic is administered into deeper tissues. Some authors caution that the bacteriostatic activity of lidocaine may interfere with culture results if injected into the joint space (6). In some joints where it may be difficult to aspirate fluid, intra-articular injection of anesthetic is helpful in minimizing discomfort.

Prepare Your Equipment

At this point, confirm that you have all the materials needed. For larger joints this includes a 60cc or two 30 cc syringes and an 18 gauge needle. Smaller needles and syringes may be used for smaller joints. Also be certain that you have all appropriate collecting tubes.

Please refer to the Equipment section for a full list of required items.

Perform the Arthrocentesis
Confirm your landmarks. The needle and syringe are advanced into the joint space with continuous traction on the plunger until fluid is attained. Use caution to minimize excessive motion of the needle as this may damage articular cartilage. As much fluid as possible should be aspirated, and if necessary, a full syringe may be replaced by an empty one for larger volumes. The opposite side of the joint may be "milked" to maximize joint decompression.

 

  

You may also withdraw the needle slightly backward 0.5-1.0 cm to pull the tip of the needle away from collapsing synovial tissues. When complete, remove the needle. Cleanse the patient's skin of excessive betadeine and apply an adhesive bandage.

Send Fluid for Analysis

The fluid should immediately be placed into proper collecting tubes. Complete analysis can usually be performed with as little as 10-15 cc of fluid (7). However, if only a few ml of fluid are obtained, cultures and microscopy should receive priority. All tubes should be filled at least half way.

 

  • RED TOP (no additive): Sent for chemistries such as protein and glucose. Of note, serum specimens for reference should also be sent at this time.

 

  • PUPRLE TOP (EDTA prevents clotting): This tube is used for microscopy, cell count and differentials

 

  • GREEN TOP (Sodium heparin prevents clotting and does not crystallize (unlike EDTA)): This tube should be sent for crystal examination.

 

The remaining fluid (ideally at least 5 cc) should be placed in appropriate culture media.

Post-procedure Care and Instructions

A clean dry sterile dressing or adhesive bandaging should be applied to the wound. The patient may take NSAIDs for pain control, if not contraindicated. The patient should be instructed to look for signs of local infection including erythema, warmth, or increased swelling, or systemic signs such as fevers and chills. A significant increase in pain and swelling can also occur if a large hematoma develops. Patients should report these symptoms to their doctors. The joint should be rested from strenuous activity as well (15).

 

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