Risk Factors for Complications After Knee Replacement

Knee replacement surgery complications were most likely to occur in patients who were older or obese

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) While knee replacement surgery can help to improve mobility, there can be complications connected to this procedure. And some patients may be at a higher risk for experiencing these complications than others.

A recent study found that being older, having diabetes and being obese were significant risk factors for death or experiencing complications like wound infections in the 30 days after knee replacement surgery.

The authors of this study noted that patients and physicians should be mindful of any new symptoms or pain that occurs after having knee replacement surgery.

"Learn how to look for symptoms of post-surgical infection."

This study was led by Philip J. Belmont Jr., MD, of the Department of Orthopaedic Surgery in the William Beaumont Army Medical Center at Texas Tech University Health Sciences Center in El Paso. This research team examined the risk factors for complications and/or death in the 30 days following total knee arthroplasty.

Total knee arthroplasty (also known as knee replacement surgery) is a surgical procedure in which the knee is replaced with an artificial joint.

Dr. Belmont and team analyzed data from 15,321 patients in the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) between 2006 and 2010. Patients were excluded if they had knee replacement surgery on both knees.

These researchers looked at the rate of complications experienced in the 30 days following surgery as well as the rate of death. Complications were categorized as major and minor systemic complications and major and minor local complications. Systemic refers to an entire system being affected and local refers to a specific region or body part being affected.

Major systemic complications included renal (kidney) failure, septic shock (bacterial infection that causes very low blood pressure) and pulmonary embolism (blood clot that travels to the lung and causes difficulty breathing). Minor systemic complications included pneumonia and urinary tract infection.

Major local complications included deep wound infections, and minor local complications included a shallow wound infection.

The researchers took several factors into account when analyzing their findings, including age, sex, body mass index (a measure of height and weight), presence of other medical conditions such as diabetes and heart disease, time of procedures and length of hospital stay following the procedure.

The researchers found that about 6 percent of patients experienced complications from the surgery in the 30-day study period. A total of 27 patients out of the 15,321 in the study population died in the 30-day study period which translates to less than 1 percent.

The most common type of complication was a minor systemic complication, experienced by about 3 percent of the study population in the 30-day period.

The researchers found that patients with diabetes were three times more likely to die after having knee replacement surgery than patients without diabetes. Patients who were 80 years of age or older were more than two and a half times more likely to experience a major systemic complication such as septic shock.

Patients with a body mass index of 40 or greater (morbidly obese) were about two and a half times more likely to experience a minor local complication such as a shallow wound infection. Cardiac disease patients were also more likely to experience a minor local complication with a risk of about six and a half times greater than non-cardiac disease patients.

The study's authors noted that higher body mass indexes and older age were significant risk factors for any complication after knee replacement surgery, while older age and diabetes were significant risk factors for death.

These researchers concluded that physicians and patients should talk about and address any complications that may arise following knee replacement surgery.

This study was published on January 1 in the Journal of Bone & Joint Surgery.

One or more of the study authors reported potential competing interests with a biomedical organization that could be perceived as having an influence on the work.

Review Date: 
January 9, 2014
Last Updated:
January 10, 2014