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Synvisc-One Knee Injection Complications

Synvisc-One knee injection complications range from joint pain to infections. The more common reactions to the arthritis treatment aren’t usually serious and tend to go away relatively soon after injection. However, patients who received contaminated gel needed to be treated in a hospital.

About 6 percent of people injected with Synvisc-One during clinical trials reported some type of side effect. Reactions to the arthritis gel generally went away on their own or with minimal treatment.

According to the drug’s maker, side effects sometimes seen after injection include joint pain and swelling. A contaminated batch of Synvisc-One knee injections led to an increase in reported complications in 2017.

Common Side Effects

The package insert for the arthritis injections says the most commonly reported problems associated with them include pain, swelling, heat, redness and fluid build-up around the knee. The manufacturer says these reactions are usually mild and don’t last long.

Patients with Device-Related Adverse Events in the Injected Knee
MedDRA Preferred Term Synvisc-One® N=123 n (%) Saline Control N=130 n (%)
Any Device-Related Adverse Event 7 (5.7%) 4 (3.1%)
Arthralgia 2 (1.6%) 3 (2.3%)
Arthritis 1 (0.8%) 0
Arthropathy 1 (0.8%) 0
Injection site pain 1 (0.8%) 1 (0.8%)
Joint effusion 2 (1.6%) 0
Source: Sanofi

They are typically treated by resting and applying ice to the affected knee. Sometimes, it’s necessary to take pain relievers such as acetaminophen or non-steroidal anti-inflammatory medications. A doctor may decide to inject steroids or remove fluid from the knee joint.

Rare cases of knee joint infections have also been reported, according to the manufacturer. Rare complications discovered after the injections were on the market include:
  • Rash
  • Hives
  • Itching
  • Fever
  • Nausea
  • Headache
  • Dizziness
  • Chills
  • Muscle cramps
  • Paresthesia
  • Peripheral edema
  • Malaise
  • Respiratory difficulties
  • Flushing and facial swelling

The label says there have been rare reports of thrombocytopenia, a condition in which blood has a lower than normal number of platelets. Platelets are blood cell fragments that stick together to form clots and stop bleeding.

Patients and doctors have also reported reactions involving hypersensitivity to the injections, including severe allergic responses.

Contaminated Gel Complications

Sanofi Genzyme saw a spike in reported complications from its Synvisc-One knee injections in late 2017. The reports often mirrored common side effects of the arthritis gel. But the number of complaints was higher than expected. In some cases, patients reported more severe symptoms.

The company investigated and discovered gram-negative bacteria had contaminated some syringes. Gram-negative bacteria include E. coli and Salmonella as well as several other difficult-to-treat bacteria. Sanofi Genzyme did not name the exact bacteria that contaminated the syringes.

The bacteria can cause pneumonia and bloodstream, wound and surgical-site infections. Some are resistant to antibiotics. This can force health care providers to rely on older drugs for treatment. But older antibiotics may have toxic side effects.

The manufacturer recalled 18,000 syringes in December 2017. The recall notice warned that the affected lot “may result in the risk of infection.”

The side effects from the contaminated lot mimicked typical complications. But some patients reported issues that required outpatient, emergency room and hospital treatment.

What To Do
If you have questions about the Synvisc-One recall, call Sanofi Medical Information Services at 1-800-633-1610, and select option 1.
Source: U.S. Food and Drug Administration

Several people experienced severe pain and swelling after the arthritis treatments. Doctors and patients reported the complications to the U.S. Food and Drug Administration.

One report said a patient became unstable after an injection. The patient’s knee was unable to support her weight. Another patient reportedly spent a week in bed after an injection.

Some patients needed multiple outpatient treatments to drain fluid from their knees. Others required emergency room visits or hospitalization.

People who received contaminated injections and then suffered complications are filing Synvisc-One lawsuits against Sanofi Genzyme and Genzyme Biosurgery.

Synvisc-One Box
Synvisc-One Injection Complications
  1. Most Commonly Reported Side Effects Pain in the knee or at the injection site; stiffness, swelling or warmth around the knee; arthritis; inflammation; fluid build-up around the joint; limping or other changes in the way a patient walks
  2. Other Adverse Reactions Reported During Clinical Trails Headache, back pain, sore throat, the flu, feeling faint

Please seek the advice of a medical professional before making health care decisions.

Related Pages
Terry Turner
Written By Terry Turner Writer

Terry Turner has been writing articles and producing news broadcasts for more than 25 years. He covers FDA policy, proton pump inhibitors, and medical devices such as hernia mesh, IVC filters, and hip and knee implants. An Emmy-winning journalist, he has reported on health and medical policy issues before Congress, the FDA and other federal agencies. Some of his qualifications include:

  • American Medical Writers Association (AMWA) and The Alliance of Professional Health Advocates member
  • Centers for Disease Control and Prevention Health Literacy certificates
  • Original works published or cited in Washington Examiner, MedPage Today and The New York Times
  • Appeared as an expert panelist on hernia mesh lawsuits on the BBC
Edited By
Emily Miller
Emily Miller Managing Editor
Medically Reviewed By
Dr. Aimee V. Hachigian-Gould
Dr. Aimee V. Hachigian-Gould Orthopedic Surgeon

15 Cited Research Articles writers follow rigorous sourcing guidelines and cite only trustworthy sources of information, including peer-reviewed journals, court records, academic organizations, highly regarded nonprofit organizations, government reports and interviews with qualified experts. Review our editorial policy to learn more about our process for producing accurate, current and balanced content.

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  10. Sanofi Genzyme. (2009, February 26). FDA Approves Genzyme’s Synvisc-One for Osteoarthritis of the Knee. Retrieved from
  11. Sanofi Biosurgery. (n.d.). Synvisc-One; A Different Way to Treat. Retrieved from
  12. Sanofi. (2017, December 19). Voluntary Recall of Synvisc-One Lot 7RSL021. Retrieved from
  13. Sanofi Genzyme. (2017, December 11). Urgent: Voluntary Device Recall. American Academy of Physical Medicine and Rehabilitation. Retrieved from
  14. National Heart, Lung and Blood Institute. (n.d.). Thrombocytopenia. Retrieved from
  15. Sanofi. (n.d.). Synvisc One Package Insert. Retrieved from
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