Obesity increases incidence, severity, costs of knee dislocations

November 3, 2017
Patient x-ray of a particularly severe knee discloation. Credit: Dr. Joey Johnson

A new study of more than 19,000 knee dislocation cases in the U.S. between 2000 and 2012 provides a painful indication of how the nation's obesity epidemic is changing the risk, severity and cost of a traumatic injury.

"Obesity greatly increases the complications and costs of care," said lead author Dr. Joey Johnson, 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 who are obese is increasing, so we are seeing more of these problems."

Addressing obesity, said co-author Dr. Christopher Born, a professor of orthopaedics at Brown, could therefore help reverse the trends in the data reported in the Journal of Orthopaedic Trauma.

Obesity's effects

Knee dislocations occur when the knee is badly disrupted because of multiple torn ligaments in the joint. Typically, this happens in vehicle crashes or contact sports like football. But Johnson and Born were inspired to look into the role of obesity because of what they've observed clinically over the last five years: an increase in knee dislocations among with an increased risk of to the main artery that runs down the leg behind the knee.

Moreover, Johnson and Born have seen an increase in "low-energy" causes of dislocations, especially among obese patients. A few years ago, for example, Johnson saw a patient who experienced a knee dislocation after stepping off a ladder while hanging curtains.

To understand what's going on more comprehensively, they analyzed records in the Nationwide Inpatient Sample, a database of patients who've had hospital stays. Over the study period, they found that obese or morbidly obese patients made up an increasing share of knee dislocation patients, rising to 19 percent of patients in 2012 compared to just 8 percent in 2000.

Vascular injury is a particularly severe complication because if undiscovered and untreated, it can lead to amputation of the leg. The team's calculations from the data revealed that the odds of vascular injury during a knee dislocation were twice as high among obese or than for normal-weight people.

Johnson said this finding is particularly insidious because a common clinical assumption is that vascular injury might be less likely among people suffering a low-energy knee dislocation. He and Born said the new research suggests physicians should be especially vigilant about vascular injury in obese knee dislocation patients, regardless of the cause.

"Orthopaedic and emergency medicine clinicians should have a heightened awareness for the potential of a knee dislocation in the obese patient following a low-energy fall," Born said. "That subset of obese patients who come in with complaints of pain need to be carefully evaluated so as not to miss a potentially catastrophic vascular injury."

The stakes, Johnson added, could be the leg itself.

"You don't want to be fooled," he said. "That patient could lose the leg, and their life could be changed forever."

In addition to increased incidence and the likelihood of vascular injury, the researchers looked at the costs of care. Patients with vascular injury, which was twice as likely among obese patients, stayed in the hospital for an average of 15.3 days, while patients without vascular injury stayed for an average of 7.4 days. In keeping with that difference, average hospitalization costs were $131,478 for vascular cases and $60,241 for those who avoided vascular damage.

"This study shows the power of using large databases to glean meaningful clinical and economic information that can significantly impact health care costs," Born said.

Though the data leave off in 2012, which is when Johnson began his residency, he said the trends are quite likely to have remained on track.

"Nothing would lead me to believe that the trend has been halted in any way," he said.

Explore further: Preventing long-term complications of an ACL tear

More information: Joey P. Johnson et al, Increased Incidence of Vascular Injury In Obese Patients with Knee Dislocations, Journal of Orthopaedic Trauma (2017). DOI: 10.1097/BOT.0000000000001027

Related Stories

Preventing long-term complications of an ACL tear

May 1, 2017
A torn ACL (also known as the anterior cruciate ligament) is one of the most common knee injuries, with as many as 200,000 cases per year in the U.S. Young people under the age of 20 are at particular risk, in part because ...

Overweight/obesity up incidence of hand, hip, knee osteoarthritis

August 3, 2016
(HealthDay)—The incidence of hand, hip, and knee osteoarthritis (OA) increases with overweight and obesity, particularly in the knee, according to a study published in the August issue of Arthritis & Rheumatology.

Weighing nonsurgical treatment options for knee osteoarthritis pain

September 19, 2017
Osteoarthritis (OA) is a progressive "wear and tear" disease of the joint. Osteoarthritis of the knee (knee OA) may not be totally preventable but according to Elizabeth Matzkin, MD, an orthopaedic surgeon specializing in ...

Excess weight predicts younger age at hip and knee replacement

June 1, 2017
A 2010 study sought to determine the effect of weight status on the age at which individuals elected to have knee or hip replacement surgery.

Knee replacement not an 'easy solution' for obese patients

October 24, 2012
Obese patients have a greater risk of complications following total knee replacement surgery, including post-surgical infections, according to a new literature review recently published in the Journal of Bone and Joint Surgery ...

Morbidly obese patients may benefit from bariatric surgery prior to knee replacement

January 21, 2016
Previous research studies have linked obesity to adverse outcomes and increased costs following total knee replacement surgery (TKR). A new, computer model-based evaluation appearing in the Journal of Bone and Joint Surgery, ...

Recommended for you

Twin saves brother's skin in transplant first

November 23, 2017
A man who had suffered burns over 95 percent of his body, putting him on the verge of death, was saved by a skin transplant from his identical twin in a world-first operation, French doctors said Thursday.

Is a common shoulder surgery useless?

November 21, 2017
(HealthDay)—New research casts doubt on the true effectiveness of a common type of surgery used to ease shoulder pain.

Study shows electric bandages can fight biofilm infection, antimicrobial resistance

November 6, 2017
Researchers at The Ohio State University Wexner Medical Center have shown - for the first time - that special bandages using weak electric fields to disrupt bacterial biofilm infection can prevent infections, combat antibiotic ...

Obesity increases incidence, severity, costs of knee dislocations

November 3, 2017
A new study of more than 19,000 knee dislocation cases in the U.S. between 2000 and 2012 provides a painful indication of how the nation's obesity epidemic is changing the risk, severity and cost of a traumatic injury.

Defining optimal opioid pain medication prescription length following surgery

September 27, 2017
A new study led by researchers at the Center for Surgery and Public Health at Brigham and Women's Hospital analyzed opioid prescription data from the Department of Defense Military Health System Data Repository, identifying ...

Is older blood OK to use in a transfusion?

September 27, 2017
(HealthDay)—Using older red blood cells to give transfusions to critically ill patients doesn't appear to affect their risk of dying, Australian researchers report.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.