Frequently Asked Questions


Please complete the online or fax the completed Synovasure Physician Enrollment Form to CD Laboratories at 410-415-1951 (or email to [email protected]). Enrollments are typically processed within 72 hours of receipt. To order kits, contact you local Zimmer Biomet distributor or call Zimmer Biomet Customer Service at 800-348-2759 (Option 1).

Synovasure Comprehensive Infection Panel testing is exclusively serviced by CD Laboratories® (CLIA License# 21D0216863), a subsidiary of Zimmer Biomet, located in Baltimore, MD.

As part of the Synovasure Comprehensive PJI Panel the following tests are performed:

  • Synovasure Alpha Defensin
  • Synovasure Microbial Identification*
  • Synovial Fluid C-reactive Protein (CRP)
  • Culture
  • WBC count with differential

Optional Add-on: Crystal Analysis

In addition, specimen integrity testing is performed on all specimens received at CD Laboratories for PJI testing.

*Note: Synovasure Microbial Identification is not currently available for patients from New York state.

As part of the Synovasure Comprehensive NSA Panel* the following tests are performed:

  • Synovasure Alpha Defensin for NSA (includes alpha defensin and lactate)
  • Synovasure Microbial Identification
  • Culture
  • WBC count with differential
  • Crystal Analysis

In addition, specimen integrity testing is performed on all specimens received at CD Laboratories for NSA testing.

*Note: The Synovasure Comprehensive NSA Panel is not currently available for patients from New York state.

The Synovasure Infection Transportation kit contains the materials needed to send synovial fluid specimens to CD Laboratories including:

  • Submission Instructions Sheet
  • 95 kPa Specimen Transport Biohazard Bag
  • Specimen Tubes (2 clear top, red stopper and 1 Lavender top)
  • Test Requisition Form
  • Biological Specimen Box
  • Prepaid FedEx Pouch for Biological Specimens
  • Prepaid FedEx shipping label
  • Patient record labels (x4)

After the testing is completed, results are sent via a protected PDF email or fax, as noted as the preferred method by practice upon enrollment with CD Laboratories®.

Results are provided for all tests requested and are intended to be used in conjunction with other clinical and diagnostic findings to aid a patient’s diagnosis. For description of each test, refer to the reverse side of the Test Requisition Form, Results Report, or click here.

Test results have been validated for specimens up to 4 days from original aspiration. It is recommended that specimens be sent to CD Laboratories as soon as possible, preferably the same day as aspiration or the following day. If needed, specimens can be refrigerated for 3 days. Refrigeration is recommended if the specimen is waiting over a weekend for shipment (See How do I treat a specimen if I see the patient on Friday? for more information). Specimens received on Day 6 or greater from aspiration will be rejected.

Our tests are validated for use with synovial fluid obtained from intra-articular joints. Other specimens may be rejected by the laboratory for testing.

Most test results are available within 24 hours of the receipt of specimen at CD Laboratories except Culture. At CD Laboratories, specimens are held to culture for 7 days (14 days for shoulder specimens). To ensure quick turnaround, please ensure that the test requisition form is fully completed and tubes are labeled with patient name and date of birth. Failure to do so will result in specimen processing delays.

The physician’s office can track the shipment using the tracking number on the FedEx return label provided in the Synovasure Infection Specimen Transportation Kit.

Specific shipment instructions are provided on the Test Submission Instructions included in each kit to ensure that the specimens are picked up and delivered in a timely fashion. To schedule your “prepaid pickup”, call 1-800-463-3339 (1-800-GOFEDEX).

Note: Packages CANNOT be placed in a FedEx dropbox.

If you aspirate a synovial fluid sample on Friday or over the weekend, please refrigerate the specimen and ship it on Monday. A sample can be refrigerated for up to 3 days.

Specimens are rejected for the following reasons:

1. Specimen is outside stability range
2. Specimen is not representative of synovial fluid (i.e. blood, urine, etc.)
3. Specimen is aspirated from a location other than the intra-articular joint space
4. Specimen is received in an expired tube

*Note: Non-synovial fluid or non-intraarticular joint specimens will be tested if associated with a Zimmer Biomet-approved clinical study

The amount of fluid needed depends on the test selected. The volumes requested are:

  • Synovasure Comprehensive PJI Panel: 6.5mL (+ 0.5mL for optional Crystal Analysis add-on)
  • Synovasure Comprehensive NSA Panel: 7.0mL
  • Synovasure Alpha Defensin for PJI: 0.5mL
  • Synovasure Microbial Identification: 1.0mL

If the above amounts are not possible, do not use saline or other additives to dilute fluid and increase volume. It is recommended to send CD Laboratories as much fluid as possible. We will perform as many of the requested tests as possible. Alpha Defensin will be the first tested followed by a test hierarchy.

Synovasure® Alpha Defensin ELISA

Synovasure Alpha Defensin ELISA test is a Laboratory Developed Test (LDT) that uses synovial fluid to aid in the diagnosis of joint infection. The test is available in two (2) formats: Synovasure Alpha Defensin for Periprosthetic Joint Infection (PJI) and Synovasure Alpha Defensin for Native Septic Arthritis (NSA).

The Synovasure Alpha Defensin for PJI Test includes: 

  • Measurement of synovial fluid alpha defensin 
  • Measurement of synovial fluid CRP

The Synovasure Alpha Defensin for NSA Test includes:

  • Measurement of synovial fluid alpha defensin 
  • Measurement of synovial fluid lactate

Several studies have evaluated the performance of Synovasure Alpha Defensin to aid in the diagnosis of Periprosthetic Joint Infection (PJI) using the Musculoskeletal Infection Society (MSIS) definition of infection as the “gold standard”. These studies have shown a combined 95% Sensitivity and 97% Specificity1.

In a clinical study, Synovasure Alpha Defensin outperformed the LE test strip in both accuracy and the ability to provide valid results. The LE strip yielded a sensitivity of 69% and was unreadable due to blood contamination 17% of specimens. Conversely, the alpha defensin assay could be read in all specimens and yielded a sensitivity of 100%2

Synovasure® Alpha Defensin is intended to assess an arthroplasty for Periprosthetic Joint Infection (PJI) prior to surgical revision. At this time, the test is not validated for use in timing of reimplantation

Clinical studies have shown that the Synovasure Alpha Defensin test is unaffected by the prior administration of antibiotics3,4

Yes. There is an increased risk of false positive with the Synovasure Alpha Defensin test in patients with metal debris or metallosis. In these situations, additional tests should be used in conjunction with alpha defensin to determine the presence of infection.

Saline washing is not approved as a collection method for Synovasure Alpha Defensin, as this will dilute the protein levels in the synovial fluid and potentially yield false negative results.

It is not recommended to utilize a contrast agent, as it will dilute the protein levels in the synovial fluid and potentially yield false negative results.

Synovasure® Microbial Identification

Synovasure Microbial ID test is a bead-based antigen test that identifies common organisms that potentially cause Periprosthetic Joint Infection (PJI) in 24 hours.

Synovasure Microbial ID test identifies more than 70%5 of organisms that cause PJI including:
  • Staphylococcus species
  • Enterococcus species
  • Candida species
  • C. acnes
In addition, the test has demonstrated the ability to identify 54% of culture-negative organisms6.

Generally, culture typically takes 3 or more days to complete, whereas the Synovasure Microbial Identification test identifies organisms in 24 hours. It is recommended that culture be performed with Synovasure Microbial Identification to obtain susceptibility for organisms.


Upon completion of testing, CD Laboratories will handle billing for testing based on a patient’s insurance:

  • Medicare: CD Laboratories bills Medicare directly on behalf of the patient
  • Non-Medicare: CD Laboratories bills patient directly. In parallel a courtesy claim is placed on patient’s insurance. Any available reimbursement will be provided back to patient by their insurance provider.

For most patients CD Laboratories is an out-of-network provider as it is located in Maryland. The Synovasure laboratory testing is only available through CD Laboratories as it is proprietary to our laboratory, so testing cannot be performed at any other laboratory including LabCorp or Quest Diagnostics. For more information regarding our status as out-of-network, click here.

  1. Synovasure Alpha Defensin ELISA Instructions for Use (IFU).
  2. Deirmengian C., et al. The Alpha-defensin Test for Periprosthetic Joint Infection Outperforms the Leukocyte Esterase Test Strip. Clinical Orthopedics and Related Research. 473:198–203, 2015.
  3. Deirmengian C., et al. Combined Measurement of Synovial Fluid a-Defensin and C-Reactive Protein Levels: Highly Accurate for Diagnosing Periprosthetic Joint Infection. Journal of Bone and Joint Surgery. 96(17):1439-45, 2014.
  4. Shahi A., et al. The Alpha-Defensin Test for Periprosthetic Joint Infection is Not Affected by Prior Antibiotic Administration. Clinical Orthopedics and Related Research. 474(7):1610-5, 2016
  5. Synovasure Microbial Identification Instructions for Use (IFU)
  6. Deirmengian C, et al. Diagnostic Performance of the Synovasure MID Test [abstract]. In: Proceedings of the MSIS Annual Meeting; 2019 Aug 2-3; New York, NY