What to Know About Joint Replacement If You Have Diabetes

Steps to Prevent Complications in Diabetics Having Joint Replacement Surgery

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Diabetes mellitus is a condition that causes increased (and decreased) levels of blood sugar, and can lead to nervous system, vascular, and immune defense problems. Over 25 million Americans have either type I or type II diabetes, and both can cause problems in people considering elective surgical procedures. Among the most common elective surgeries are joint replacement surgery including knee replacement, hip replacement, and shoulder replacement.

People who have diabetes mellitus, or have elevated blood glucose levels even without having a diagnosis of diabetes, require careful planning to help prevent complications as a result of poorly controlled blood glucose levels. On a positive note, efforts to control diabetes and improved management of blood glucose levels can have a positive impact in terms of lowering the risks associated with surgery.

Elevated Blood Sugar

Approximately 8 percent of people having a joint replacement in the United States have either type I or type II diabetes. Having the diagnosis of diabetes increases the risks of joint replacement surgery. Furthermore, that increase in risk is correlated with how well (or poorly) controlled the blood glucose levels are at the time of surgery. Having a diagnosis of diabetes does not mean you can't proceed with joint replacement, it just means the risks of surgery may be slightly higher, and everything possible should be done to minimize that increased risk of complications.

Diabetes causes problems to the body's vascular, nervous, and immune systems. Microvascular disease (damage to the smallest blood vessels) can limit blood flow and oxygen delivery to the location of a healing surgical incision. The altered immune function can not only impair the body's immune defense system, but also make the body more susceptible to harboring a bacterial infection.

Surgical results of people who have diabetes are generally worse that those without diabetes for a variety of surgical procedures, not just joint replacement. Studies have demonstrated increased risk with orthopedic surgeries including foot surgery, spine surgery, and fracture surgery. Other surgical specialties also have examples of diabetes being a risk factor for possible complications. Again, these results tend to correlate with the severity of the condition in terms of how well, or poorly, the blood glucose levels can be controlled.

Impact on Risks of Joint Replacement Surgery

There are several ways in which people with diabetes are affected when having joint replacement surgery. Diabetes increases the risk of a number of complications, not just one in particular. Some of the more concerning problems seen in diabetic patients who are having joint replacement include:

  • Higher risk of infection: Infection risk is one of the most concerning aspects of joint replacement surgery. When infection of a joint replacement occurs, additional surgery is almost always necessary, and often the implants have to be removed in order to cure the infection.
  • Higher risk of wound healing problems: Healing of the surgical incision seems straightforward, but persistent drainage, wound necrosis, and non-healing incisions can all occur in people with diabetes. An un-healed surgical incision is a cause of infection in people with joint replacements.
  • Higher risk of medical complications: Many medical conditions including pneumonia, urinary tract infections, and pulmonary embolism can all be more likely in people with diabetes. 
  • Increase risk of transfusion: Transfusions are becoming increasingly rare after a standard joint replacement. With new medications and wound closure techniques, the likelihood of transfusion has gone down significantly. However, the risk is higher in people with diabetes.
  • Increased mortality risk: This is scary to think about, and while the risk of mortality associated with joint replacement is very small, it is not zero. Furthermore, people who have poorly controlled diabetes do have a higher risk of mortality with elective surgery like joint replacement.

Controlling Blood Glucose Levels

There is good news! I hate to always bring bad news to the table, and there is no question that people with difficulty controlling blood sugar often have to face difficult medical problems. The good news is that by optimizing the control of blood sugar, over both the short term and long term, the risks of having joint replacement don't have to go up dramatically.

Many studies have shown that the risks mentioned in this article correlate very closely with how well blood sugar is controlled. This is true for blood sugar control over the months around surgery, and in the days around surgery. Therefore, efforts to stabilize and control blood sugar through diet, exercise, medications, and other means can help to prevent complications associated with a joint replacement surgery.

Blood sugar measurements are generally measured in one of two ways:

  1. Glucose level: A blood glucose level is usually measured when fasting (shortly before a meal, not after) and around 70-100. In people with well-controlled diabetes, this number may be in the range of 90-130. Blood glucose levels can rise dramatically, especially in people with diabetes. After a meal, it is not uncommon to be close to 200 or higher in someone with diabetes, whereas in people without this condition, blood glucose typically doesn't go above 125.
  2. Hemoglobin A1c: The hemoglobin A1c, or HbA1c, is a measure of average blood glucose levels over the months preceding the test. It does not give a snapshot of a moment in time, but rather a general sense of how well, or poorly, controlled the blood sugars are. Someone without diabetes will typically have a hemoglobin A1c level of approximately 5.0, whereas someone with diabetes is more than 6.5 (although there is some disagreement over the precise level which defines diabetes, most agree in the range of 6.5 to 7.0). When working to adjust management of blood glucose, changes in hemoglobin A1c can take months to detect.

    Both of these measures can be helpful in different ways, but neither is perfect. For example, having a blood glucose level more than 200 at the time of joint replacement has been shown to be a risk factor for complications, even if the A1c is well controlled. Similarly, having a normal blood glucose on the day of surgery in the setting of a high A1c does not mean you are risk free. Both tests can help people manage their glucose control and limit their risks related to joint replacement surgery.

    Should There Be a Cutoff?

    Some joint replacement centers have established a system by which they require a specific test result in order to proceed with joint replacement surgery. The most commonly used test is the hemoglobin A1c. In an effort to ensure people undergoing joint replacement have reasonably well controlled diabetes, some centers require a specific hemoglobin A1c result, such as a level below 7.5 or below 8. When an individual has a hemoglobin A1c that is above this threshold, they may not be offered joint replacement surgery. Often, joint replacement centers that have this type of threshold will also have a program that helps people with elevated blood sugars take the appropriate steps to get their hemoglobin A1c back to a safer level.

    Interestingly, hemoglobin A1c is probably not the best test to predict the likelihood of complication related to joint replacement, but it is a convenient test to obtain, and it gives a good indication of how well an individual can control their blood sugar levels. Exactly what number is safe, and what is not, is controversial, but some joint replacement centers have defined their cutoff for these procedures.

    A recent study of a shoulder replacement registry of over 18,000 patients found that the cutoff in this group was a hemoglobin A1c of 8.0 or higher. In these patients, there was much high risk of deep infection and wound healing problems. On a positive note, the overall risk of complications in this group of 18,000 patients was very low (about 1 percent), and even though the risk was almost double in people with an A1c over 8, the risk was still only about 2 percent.

    There is always frustration among people who need joint replacement surgery when their surgeon does not recommend proceeding because of the possibility of complications of surgery. Note that your surgeon has your best interest in mind, and seeing some of these complications such as infection and wound healing problems on a regular basis makes orthopedic surgeons very cautious in working with people who have an increased risk of complications from surgery. If your doctor recommends postponing joint replacement surgery because of blood sugar concerns, work with him or her to address those concerns, and know that they have your best interests in mind.

    A Word From Verywell

    This sounds like a lot of bad news, so let me end with the positive: Thousands of people with diabetes undergo successful and life-transforming joint replacement surgery every year. While there may be increased risks of surgical complications, those risks can be managed. Controlling blood sugar levels, particularly in the time around surgery, is thought to be the most important factor in managing these risks. People with diabetes should not fear joint replacement, but they should work with their doctors to optimize their blood sugar control to keep their risks associated with joint replacement surgery as low as possible.

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