Synovial Fluid Analysis of Knee Joint

Synovial Fluid Analysis of Knee Joint

Bone, Muscle, & Joint
Laboratory Procedures
Contributed byMaulik P. Purohit MD MPHMay 10, 2019

What are the other Names for this Test? (Equivalent Terms)

  • Knee Joint Fluid Analysis Test

What is Synovial Fluid Analysis of Knee Joint? (Background Information)

  • Synovial fluid is a thick substance found in the major joints of the body (such as the shoulder, hip, elbow, wrist, knee, and ankle), most notably in the knee. It acts as a lubricant, shock absorber, and nutrient medium
  • A joint links the ends of bones together and enables them to articulate or move against one another. However, the bones do not physically touch each other, as this would cause bone degradation and pain. Instead, the articular surfaces of bones are covered by articular cartilage. This is a smooth form of cartilage that is less dense and thus slicker than other cartilages
  • The synovial fluid fills the spaces between articular surfaces within the joints. Articular cartilage is also permeable to synovial fluid. This enables the two to work together to provide further joint protection
  • When articular cartilage is compressed, it pushes synovial fluid out and into the joint, where the fluid can lubricate the opposing surfaces. When compression is relieved, the fluid re-enters the articular cartilage. Similarly, synovial fluid acts as a shock absorber. Forces felt by the joints are spread across the synovial fluid, lessening stress on the articular surfaces
  • Another important function of synovial fluid is to exchange wastes and nutrients with the surrounding capillaries. This allows for proper maintenance of the joint tissue
  • The joint disorders are categorized into 5 groups:
    • Non-inflammatory
    • Inflammatory
    • Crystal-induced
    • Septic
    • Hemorrhagic

The Synovial Fluid Analysis of Knee Joint evaluates several aspects of the synovial fluid to assess joint health and differentiate between different types of joint disorders. The aspects evaluated include:

  • Appearance: Color, turbidity, and other visual properties
  • Chemistry: Glucose, pH, proteins, lactic acid, and uric acid
  • Microscopic examination: White blood cells, red blood cells, and polarized light analysis to detect crystals
  • Infectious disease analysis: Gram stain, culture, and smear to detect pathogens

What are the Clinical Indications for performing the Synovial Fluid Analysis of Knee Joint?

Following are the clinical indications for performing a Synovial Fluid Analysis of Knee Joint:

  • Following-up to a physical examination
  • Monitoring a joint disorder
  • Recent injury
  • Swelling
  • Redness
  • Pain

How is the Specimen Collected for Synovial Fluid Analysis of Knee Joint?

Following is the specimen collection process for Synovial Fluid Analysis of the Knee Joint:

Sample required: Synovial fluid of the knee joint

Process: Insertion of a needle into the knee joint (arthrocentesis of knee joint).

Preparation required: No special preparation is needed prior to the test. 

What is the Significance of the Synovial Fluid Analysis of Knee Joint Result?

The significance of Synovial Fluid Analysis of Knee Joint is explained:

  • Increased white blood cells, microorganisms, lactic acid, uric acid, and/or crystals in the synovial fluid may indicate:
    • Gout
    • Pseudogout
    • Osteoarthritis
    • Acute bacterial arthritis
    • Rheumatoid arthritis  
    •  Hemophilic arthritis  
    • Tuberculous arthritis   
    • Systemic lupus erythematosus
    • A significant trauma      

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results based on the overall clinical scenario. 

Additional and Relevant Useful Information:

  • The synovial fluid analysis of a joint involves the testing for uric acid and glucose levels. In order to assess the overall levels of uric acid and glucose in the body, additional blood and urine tests for these chemicals may be performed
  • Your healthcare provider will combine the findings of the blood test, urine test, synovial fluid analysis, and the overall clinical signs and symptoms to arrive at a diagnosis

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

Was this article helpful

On the Article

Maulik P. Purohit MD MPH picture
Approved by

Maulik P. Purohit MD MPH

Assistant Medical Director, Medical Editorial Board, DoveMed Team


Please log in to post a comment.

Related Articles

Test Your Knowledge

Asked by users

Related Centers


Related Specialties

Loading card

Related Physicians

Related Procedures

Related Resources

Join DoveHubs

and connect with fellow professionals

Related Directories

Who we are

At DoveMed, our utmost priority is your well-being. We are an online medical resource dedicated to providing you with accurate and up-to-date information on a wide range of medical topics. But we're more than just an information hub - we genuinely care about your health journey. That's why we offer a variety of products tailored for both healthcare consumers and professionals, because we believe in empowering everyone involved in the care process.
Our mission is to create a user-friendly healthcare technology portal that helps you make better decisions about your overall health and well-being. We understand that navigating the complexities of healthcare can be overwhelming, so we strive to be a reliable and compassionate companion on your path to wellness.
As an impartial and trusted online resource, we connect healthcare seekers, physicians, and hospitals in a marketplace that promotes a higher quality, easy-to-use healthcare experience. You can trust that our content is unbiased and impartial, as it is trusted by physicians, researchers, and university professors around the globe. Importantly, we are not influenced or owned by any pharmaceutical, medical, or media companies. At DoveMed, we are a group of passionate individuals who deeply care about improving health and wellness for people everywhere. Your well-being is at the heart of everything we do.

© 2023 DoveMed. All rights reserved. It is not the intention of DoveMed to provide specific medical advice. DoveMed urges its users to consult a qualified healthcare professional for diagnosis and answers to their personal medical questions. Always call 911 (or your local emergency number) if you have a medical emergency!