Obesity and Component Malposition
Obesity can also affect the positioning of the component in THA. Goldberg pointed to a study, “Are Morbidly obese patients undergoing total hip arthroplasty at an increased risk for component malpositioning” that was published in the September 2013 issue of the Journal of Arthroplasty.
The researchers found a significant correlation between morbid obesity and under-anteversion and using a multivariate analysis, there was also a trend toward a combined under-anteversion/over-abduction of the acetabular cup. According to their data, high BMI was the biggest risk factor leading to malpositioning.
Goldberg said that this study shows that with obese patients it doesn’t matter which surgical approach you use, you are more likely to malposition implants and need to do revision surgery if a patient is obese.
One particular study that was a game changer for Goldberg, which really made him look at his patient selection, was “Patients with Uncontrolled Components of Metabolic Syndrome Have Increased “Risk of Complications Following Total Joint Arthroplasty,” which was published in the June 2013 issue of the Journal of Arthroplasty.
He said, in this study, patients with uncontrolled metabolic syndrome had major complication rates of 49% compared to 8% in patients with controlled metabolic syndrome or no metabolic syndrome, and that the researchers concluded that “…the risk of surgical intervention in this cohort is not justified by the hope that early surgery will allow these patients to control [metabolic syndrome].”
Goldberg said, “In other words, we are not going to make them healthier by doing their surgery.”
This study’s data was backed up the next year by another one, “Impact of Metabolic Syndrome on Perioperative Complication Rates After Total Joint Arthroplasty Surgery,” which was published in the same journal in September 2014.
These researchers found that metabolic syndrome represents a concerning risk factor that has a significant impact on the outcome of the surgery and that surgeons should proceed with caution when indicating these patients for arthroplasty.
Goldberg added that a March 2016 study, “Severely Obese Patients Have a Higher Risk of Infection After Direct Anterior Approach Total Hip Arthroplasty” published in the September 2016 issue of The Journal of Arthroplasty looked specifically at the risks with the direct anterior approach to total hip arthroplasty.
In this study, he said, patients were stratified by BMI (group 1 BMI > 35; group 2 ≥35). The researchers found that there was a significantly higher infection rate that led to the need for revision in group 2 (0.35% vs. 2.5%; p = .0044)
Ultimately, Goldberg said, you want to make sure you indicate these patients very carefully for whatever procedure you decide to do.
