Aby wyświetlić tę treść, wymagana jest subskrypcja JoVE. Zaloguj się lub rozpocznij bezpłatny okres próbny.
Here the protocol describes arthrocentesis of the knee, a procedure in which a needle is inserted into the knee joint, and synovial fluid is aspirated. Synovial fluid may be removed for testing to determine the nature of the knee effusion. Arthrocentesis of the knee is typically performed with the patient supine.
Arthrocentesis of the knee is a procedure in which a needle is inserted into the knee joint, and synovial fluid is aspirated. An arthrocentesis can be diagnostic or therapeutic. Synovial fluid may be removed for testing to determine the nature of the knee effusion. If septic arthritis is suspected, urgent arthrocentesis before initiation of antibiotic treatment is indicated. Moreover, arthrocentesis can also aid in diagnosing crystal-induced arthritis such as gout or pseudogout, or non-inflammatory arthritis such as osteoarthritis. Identifying the cause of the knee effusion can guide treatment. Furthermore, removing fluid from a knee can reduce intraarticular pressure to decrease pain and improve range of motion. There is no absolute contraindication to performing this procedure, but in selecting the needle entry site, an area of skin that is infected should be avoided. Therefore, caution should be exercised when a patient presents with suspected cellulitis over the knee joint to avoid the potential risk of causing iatrogenic septic arthritis. A knee that has undergone arthroplasty should be assessed for arthrocentesis by an orthopedic surgeon. Arthrocentesis of the knee is typically performed with the patient supine. The site for needle insertion is marked, and then the skin is disinfected. After a local anesthetic is administered, a needle is inserted along the pathway that was anesthetized. Synovial fluid is aspirated, and then the needle is withdrawn. Pressure is applied until any bleeding stops. The synovial fluid can be analyzed for infection and inflammation but cannot directly confirm a diagnosis of internal derangement or autoimmune causes of arthritis. In addition to the history and physical examination, laboratory findings and imaging can clarify the etiology of a knee effusion.
Arthrocentesis is performed to successfully aspirate synovial fluid from a joint such as a knee, shoulder, elbow, wrist, or ankle. A patient with a newly detected knee effusion can undergo a diagnostic arthrocentesis to determine the nature of the effusion. Before proceeding to attempt an arthrocentesis, knee swelling by history must be confirmed on physical examination to assess whether an effusion exists. With the patient supine, the knees can be compared on inspection to see if the swelling is unilateral. The knee with the effusion may appear larger than the other knee. With a large effusion (at least 20 mL), convexity can be seen proximal to the patella. With a small effusion (5-10 mL), pressing the fluid superolaterally with one hand can allow the other hand to palpate a fluid bulge. Palpating the fluid can help decide if a successful arthrocentesis is probable. In addition to the supine position, arthrocentesis of the knee can also be done on a patient in the sitting position, but there is a higher chance that less synovial fluid would be aspirated1. Synovial fluid from the knee can be aspirated from a medial or lateral approach, but the latter is preferred in complicated circumstances2. A knee effusion is not always tender on exam and thus does not necessarily cause an antalgic gait. An urgent arthrocentesis before antibiotic treatment is indicated if septic arthritis is suspected. An orthopedic surgeon can perform a knee joint aspiration to diagnose a prosthetic joint infection in a patient who had a knee arthroplasty.
In addition to evaluating for infection, arthrocentesis can assist in identifying diagnoses, such as crystal-induced arthritis (gout or pseudogout), rheumatoid arthritis, spondyloarthritis, reactive arthritis, psoriatic arthritis, hemarthrosis, or osteoarthritis. The findings on synovial fluid analysis can lead to the appropriate treatment. In a patient with pain and restricted movement of the knee due to an effusion, aspirating the fluid can improve these symptoms. Furthermore, arthrocentesis of a knee prior to an intra-articular steroid injection has been shown to reduce the risk for arthritis relapse in rheumatoid arthritis3. There is no absolute contraindication to arthrocentesis of a knee, but the needle should be inserted away from any cellulitis to not introduce any infection into the joint. Moreover, arthrocentesis has been shown to be generally safe in patients on anticoagulation with warfarin or direct oral anticoagulants4,5,6,7. With the proper technique and clinical indication, a patient can undergo this procedure with minimal risks.
This protocol follows the guidelines at BronxCare Health System. A written informed consent is necessary from the patient.
1. Identifying anatomical structures
2. Skin sterilization
3. Anesthetizing
4. Arthrocentesis needle insertion
5. Needle removal
A prospective randomized study compared complete aspiration of synovial fluid from the knee and intra-articular injection with corticosteroid alone. It demonstrated that aspirating as much synovial fluid as possible can reduce the risk for recurrence of arthritic symptoms when treating rheumatoid arthritis patients with intra-articular corticosteroids. Figure 1 shows the reduction in the proportion of relapses in the arthrocentesis group3.
Knee arthrocentesis is a bedside or clinic procedure in which a needle is inserted into the joint capsule, and synovial fluid is aspirated. Before attempting an arthrocentesis, knee swelling by history should be confirmed to be an effusion on physical examination. A knee x-ray can reveal an effusion but is not necessary prior to aspiration. If body habitus complicates the physical examination, ultrasonography can be used to confirm effusion size and to direct insertion of the needle for aspiration8
The authors have nothing to disclose.
The authors have no acknowledgments.
Name | Company | Catalog Number | Comments |
Alcohol prep pad | Medline | MDS090670Z | sterile 2-ply pad |
Eclipse needle | BD | DGW60702 | 25G x 5/8" |
Ethyl Chloride instant topical anesthetic spray | Gebauer's | P/N 0386-0008-03 | non-flammable |
Lidocaine HCl injection | Fresenius Kabi Usa, Llc | NDC 63323-492-27 | 1% single dose vial |
Plastic bandage | Curad | CUR02278RB | 4-sided seal |
Plastipak 3 mL syringe | BD | 309651 | sterile |
Plastipak 5 mL syringe | BD | 309649 | sterile |
Povidone iodine topical solution | Major | NDC 0904-1103-09 | topical antiseptic |
Precision glide needle | BD | 305196 | 18G x 1 1/2" |
Sterile gauze sponge | CARING | PRM2208 | 2 in. x 2 in. |
Sterile regular tip surgical skin marker | MEDLINE | DYNJSM01 | |
Surgical gloves | TRIUMPH | MSG2265 | sterile & powder-free |
Zapytaj o uprawnienia na użycie tekstu lub obrazów z tego artykułu JoVE
Zapytaj o uprawnieniaThis article has been published
Video Coming Soon
Copyright © 2025 MyJoVE Corporation. Wszelkie prawa zastrzeżone