Injections Before Joint Replacement May Cause Infection

Increased Risk of Infection Associated With Preop Injections

knee injection
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Joint replacement surgery is a common treatment for severe arthritis of a joint. The most common type of joint replacement is knee replacement surgery, followed closely by hip replacement surgery. Generally, these surgical procedures are reserved for patients with severe arthritis of the joint, who have failed extensive attempts at non-surgical treatments.

One of the more common non-surgical treatments used for people with arthritis is an injection into the joint.

The most frequently used injection are steroids. One other type of injection is called viscosupplementation, an option for knee arthritis. Recent studies have questioned if these injections are safe to perform prior to planned joint replacement.

Risks of Shots Before Replacement

Researchers have looked through large databases of Medicare patients who have undergone knee replacement surgery. They were able to compare patients who had a cortisone shot (or viscosupplement injection) prior to replacement, and if that individual had an infection after replacement. The data clearly demonstrated there was a higher chance of having an infection in people who had a shot before surgery.

Furthermore, the research found that the risk of infection after surgery was strongly correlated with how soon before surgery patients had their most recent shot. If the shot was within seven months of the time of surgery the risk of complication was significantly higher.

If the shot into the joint was before seven months, there was little difference in the risk of developing infection after surgery. Therefore, the magic number seems to be seven months, where patients should avoid having injections into a joint for seven months prior to an elective joint replacement surgery.

Exactly why injections administered into a joint may increase chance of infection months down the road is not entirely clear. One possibility is that the medications may diminish the ability of the body to defend itself from infectious bacteria. Whatever the mechanism, there does appear to be a period of time during which people should be extremely cautious with anything being placed into their joint prior to having an elective joint replacement surgery. Also, while the data investigated is based on the investigation of knee replacement, it is prudent for people to be cautious with injections into any joint that is going to be replaced. Therefore, people who may be having a hip, shoulder, or ankle replacement should also avoid injections if having upcoming replacement of that joint. What this study did not show was any evidence that having an injection into another joint than the one being replaced was harmful. For example, there is no evidence that having your left knee injection prior to right knee replacement is a bad thing.

Infection After Replacement

Infections are a particularly worrisome complication of joint replacement surgery. Infections often require additional surgery to be performed, sometimes multiple surgeries. In addition, people who have an infection after a joint replacement tend to have hips and knees that don't function as well as people who don't have these complications.

Signs of a joint replacement infection may include increasing discomfort, fevers and chills, redness near the site of surgery, and drainage around an incision. Anyone who has had a recent joint replacement and is exhibiting these signs should be carefully evaluated by their surgeon. When infections are detected early the treatment may be less invasive. However, when infections get around the joint implants (a deep infection), the treatment is almost always one or more surgical procedures.

Bottom Line: Is a Shot Safe?

Recent research is pretty clear: a time of at least seven months should pass between an injection into the knee and elective knee replacement surgery of the joint injected. Performing surgery on that knee within seven months of the injection you at a higher risk for infection. Avoiding infection is very important, and every step should be taken to prevent this potentially serious complication. While the research is focused on knee injections and knee replacement, people having other joints replaced should be similarly cautious and discuss the pros and cons of any injection with their surgeon.

Sources:

McKee, J. "Injections May Increase Infection Risk in TKA Patients" AAOSNow. January 2016.

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