Being overweight is hard on the knees and the wallet: New study tracks how obesity epidemic has made knee dislocations more frequent, severe, expensive

Excess weight can result in an increased risk of knee dislocations, according to a study. This puts an excruciating focus on how obesity rates are shaping risk assessment, as well as the economics of a traumatic injury.

The study “Increased Incidence of Vascular Injury In Obese Patients with Knee Dislocations” looks at the increasing obesity rates in the U.S. to determine its relationship with closed knee dislocation and vascular complications.

“Obesity greatly increases the complications and costs of care,” according to lead author Dr. Joey Johnson, an orthopedic trauma fellow at the Warren Alpert Medical School of Brown University and a physician at Rhode Island Hospital. “As the rate of obesity increases, the rate of knee dislocations increases. The total number of patients who are obese is increasing, so we are seeing more of these problems.”

Knee dislocations occur when there are multiple torn ligaments present. Usual suspects for this include vehicular crashes and contact sports. However, the researchers stated that the underlying reason for their study was the rise in the number of obese patients who had an increased risk of vascular injury to the main artery that runs down the leg behind the knee. This is alarming, according to researchers, as cases of vascular injury are not commonly associated with low-energy knee dislocations. They further advise physicians to be thorough in identifying vascular injury for patients who have had knee dislocation, especially those who are obese.

Researchers sampled 19,000 cases of knee dislocations between 2000 to 2012. Records were taken from the Nationwide Inpatient Sample, a database of patients who have stayed in hospitals during an injury or disease. Over the course of the study, they discovered that obese and morbidly obese patients form a large percentage of those who have suffered knee dislocation, comprising 19 percent of patients in 2012 from eight percent recorded in 2012.

The results also indicated that obese patients are more likely to be prone to injuring the vascular artery, a major blood vessel running behind the knee joint and down the leg. When this is damaged, the injury can cause a serious consequences, including amputation. Patients who were obese are twice as more likely to suffer vascular injury over those who aren’t.

Aside from the elevated risk and probability of vascular injury, researchers also examined the expenses resulting from these cases of dislocation. It turns out that patients with vascular damage stayed in hospitals for an average of 15.3 days. This is higher compared to patients without vascular injury as they only had an average of 7.4 days for hospital stays. Consequently, hospital expenses for cases of vascular injury were computed at $131,478 compared to $60,241 for cases that do not have vascular damage.

“That subset of obese patients who come in with complaint of knee pain need to be carefully evaluated so as not to miss a potentially catastrophic vascular injury,” said study co-author Dr. Christopher Born, a professor of orthopedics at Brown University.

While the data only evaluates up to 2012, Researchers have stated that the trends identified have likely remained on course.

Aside from Johnson and Born, the paper’s other authors include Justin Kleiner, Dr. Stephen Klinge, Dr. Philip McClure and Dr. Roman Hayda from the department of Orthopedic Surgery at Brown University and Rhode Island Hospital.

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