Arthritis is one of the most prevalent conditions affecting nearly 1 in 4 adults in the United States. In addition, significant medical costs, as well as potential for lost wages are not uncommon with arthritis1 making an accurate and timely differential diagnosis key to potentially providing targeted conservative care and treatment to patients with knee joint pain.

At CD Laboratories, we offer the first-of-its-kind – offering a one stop, comprehensive panel of synovial fluid laboratory tests to aid in differentiating common arthritis conditions in the knee including:

  • Native Septic Arthritis (NSA)
  • Osteoarthritis (OA)
  • Rheumatoid Arthritis (RA)
  • Crystal Arthritis

Synovasure RISC® Panel

The Synovasure RISC® Panel includes synovial fluid testing for native septic arthritis through white blood cell (WBC) count with differential.

If cell count is >3,000 or PMN% >70%, specimens are reflexed for:

  • Synovasure Alpha Defensin for NSA (alpha defensin and lactate)
  • Synovasure Microbial Identification
  • Culture
For additional information on tests, click here

As part of the Synovasure RISC® Panel, synovial fluid from patients experiencing knee joint pain with suspected arthritis is evaluated for:

  • Cartilage Oligomeric Matrix Protein (COMP) – Indicates presence of cartilage degradation
  • Interleukin-8 (IL-8) – Indicates an inflammatory condition.

A COMP/IL-8 ratio is applied to delineate between patients with OA or inflammatory arthritis with secondary OA.

For additional information on tests, click here

The Synovasure RISC® Panel includes synovial fluid testing for biomarkers commonly tested via blood for RA:

  • Anti-Cyclic Citrullinated Peptide (Anti-CCP)
  • Rheumatoid Factor (RF)

An algorithm is used to combine Anti-CCP and RF for a diagnosis recommendation on RA.


For additional information on tests, click here

As part of the Synovasure RISC® Panel, specimens are analyzed under polarized microscopy for the presence of crystals prevalent in gout and calcium pyrophosphate deposition (CPPD):

  • Monosodium Urate (MSU)
  • Calcium Pyrophosphate Dihydrate (CPPD)

For additional information on tests, click here

Note: All specimens are tested for specimen integrity as part of the Synovasure RISC® Panel

Synovasure® Osteoarthritis

First-of-its-kind laboratory test to aid in the diagnosis of isolated, idiopathic OA via synovial fluid assessment:

  • Cartilage Oligomeric Matrix Protein (COMP) –  Protein biomarker of cartilage breakdown shown to have elevated concentration in the presence of OA2,3 
  • Interleukin-8 (IL-8) – Molecule that attracts and activates neutrophils shown to have elevated concentrations in cases of inflammatory arthritis (ie. RA or gout)4,5

COMP/IL-8 ratio is utilized to aid in differentiating between primary and secondary OA.

Highly Accurate for OA Diagnosis6

The COMP/IL-8 ratio demonstrated high sensitivity and specificity


COMP/IL-8 Ratio in Differentiating
OA from Other Arthritis6

Synovasure® Rheumatoid Arthritis

Synovial fluid testing for common biomarkers to aid in diagnosis of RA traditionally assessed using blood tests:

  • Anti-CCP – Autoantibody to identify and attack cells thought to be present in 60-70% of patients with RA7
  • Rheumatoid Factor (RF) – Protein to attack healthy tissue indicative of an autoimmune disease like RA when present

Using an algorithm, Anti-CCP and RF results are combined to generate a diagnosis recommendation for RA.

Performance Backed by Data6

  • Capable of differentiating between RA and Non-RA patients
  • Effective “rule-in” test
    • 100% Specificity
  1. Joint Pain and Arthritis. Accessed 30 March 2020.
  2. Bellucci F., et al. Synovial Fluid Levels of Bradykinin Correlate with Biochemical Markers for Cartilage Degradation and Inflammation in Knee Osteoarthritis. Osteoarthritis and Cartilage. 21(11) 1774-1780, 2013.
  3. Arellano R., et al. Cartilage Oligomeric Matrix Protein Levels in Synovial Fluid in Patients with Primary Knee Osteoarthritis and Healthy Controls: A Preliminary Comparative Analysis with Serum Cartilage Oligomeric Matrix Protein. Archives of Rheumatology. 32(3):189-196, 2017.
  4. Partsch G., et al. Highly Increased Levels of Tumor Necrosis Factor-alpha and Other Proinflammatory Cytokines in Psoriatic Arthritis Synovial Fluid. The Journal of Rheumatology. 24(3) 518-523, 1997.
  5. Harada A., et al. Essential Involvement of Interleukin‐8 (IL‐8) in Acute Inflammation. Journal of Leukocyte Biology, 56(5) 559-564, 1994.
  6. 12514-009 – Technical Report: Performance of Synovasure® Differential Diagnosis Arthritis Panel Diagnostic Accuracy Test
  7. Freeman, J. RA and Anti-CCP: What is the Purpose of an Anti-CCP Test? Accessed 1 Apr 2020.
  8. Street, T. Rheumatoid Factor. Accessed 1 Apr 2020.