Obesity: No Effect on Post-Multiligamentous Knee Outcomes?

When several torn ligaments in the knee are surgically treated at the same time, is postoperative stiffness an issue in obese patients? A team from New York University (NYU) Langone Health in New York, New York and the Yale School of Medicine in New Haven, Connecticut, investigated this question.

Their study, “Risk of Postoperative Stiffness Following Multiligamentous Knee Injury Surgery Is Not Affected by Obesity: A Multicenter Study” was published in the June 28, 2022, edition of Arthroscopy.

“Multiligamentous knee injuries have presented a challenging, rare, and often life-altering injury for orthopedic surgeons, with an overlap of sports and trauma specialists,” co-author Andrew Bi, M.D., an orthopedic resident at NYU Langone Orthopedic Hospital, told OTW.

“However, there is a dearth of high-quality research on these heterogenous injuries, with some recent headway being made with large collaborations such as the STaR (Surgical Timing and Rehabilitation) Trial for Multiple Ligament Knee Injuries. Our goal was to contribute to the multiligamentous knee injury literature with a two-center collaboration that see a relatively high volume of multiligamentous knee injuries.”

The researchers looked at 190 consecutive patients who had surgery for multiligamentous knee injuries between January 2001 and March 2020 and stratified the study patients according to obesity grades: grade 1 (BMI [body mass index] 30 to < 35) grade 2 (BMI 35 to < 40); grade 3 (BMI > 40) and non-obese (BMI < 30). They then compared the rate of manipulation under anesthesia between obesity grades.

The team found that the mean BMI of the cohort was 29.2 kg/m². There were 55 (29.1%) manipulation under anesthesia procedures observed at a mean 3.77 ± 2.18 months (range 1.8 – 9.7 months) after the last multiligamentous knee injury surgery. They discovered no significant difference in BMI of individuals who underwent a manipulation under anesthesia compared to patients who did not (30.2 vs. 28.8).

Comparing the groups, the researchers found no significant difference in rate or time to manipulation under anesthesia following multiligamentous knee injury surgery.

Focus on External Fixators or Blood Vessels

Dr. Bi said to OTW, “The most important results of our study were:

• obesity overall did not significantly affect rates of postoperative arthrofibrosis following surgery for multiligamentous knee injuries,
• “super obesity”, or BMI > 40, trended toward having higher rates of stiffness, but larger sample sizes are needed to identify if this signal bears out, and
• redemonstration of initial injury requiring external fixator or a vascular injury being significant predictors of postoperative stiffness following multiligamentous knee injuries surgery, indicating initial injury mechanism is the primary driver of postoperative arthrofibrosis.”

“We are enthusiastically continuing our collaboration to identify significant trends and prognostic information within our diverse multiligamentous knee injuries group through our multicenter prospective registry and hope to continue to publish our new findings.”