Injections Before Joint Replacement May Cause Infection

Risk of Infection Associated With Preop Injections

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 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 injections are steroids. One other type of injection is called viscosupplementation, an option for knee arthritis. Studies have examined whether these injections are safe to perform prior to planned joint replacement.

knee injection
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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 joint replacement, as well as whether that individual had an infection after surgery. The data clearly demonstrated there was a higher chance of having an infection in people who had an injection 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 administered longer than seven months prior to surgery, there was little difference in the risk of developing an infection after surgery. Therefore, seven months can be used as a guideline, and patients may be told to avoid having injections into a joint for seven months prior to elective joint replacement surgery. However, individual surgeons may have varying approaches to this.

Exactly why injections administered into a joint may increase the 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. In addition, while the data 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 they are 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 current evidence to suggest 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, or 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. Furthermore, an infection, in worst cases, can lead to serious systemic infections.

Signs of a joint replacement infection 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 earl,y 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?

Research is pretty clear: a period 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 may place you at 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.

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