Pre-op Tips and Tricks for the Obese Patients

A reality for orthopedic surgeons today is that more and more of the patients they consult are obese. In the United States, 32% of men and 36% of women are obese, with the obesity scale ranging from a bone mineral density (BMI) > 30 a BMI greater than 50 (super-obese).

According to Flegal et al. in “Prevalence of obesity and trend in the distribution of body mass index among US adults, 1999-2010” published on February 1, 2012 in the Journal of the American Medical Association, one-third of people in the United States are obese.

And, unfortunately, the obesity epidemic continues to grow. Its prevalence in the last 25 years has doubled. In 1985, no state had more than 15% obesity, while in 2015 no state had less than 20% obesity.

What to Do With Obese Surgical Candidates?

Tyler D. Goldberg, M.D., an affiliate assistant professor at the University of Texas, Dell Medical School in the department of surgery and perioperative care, and an orthopedic surgeon with Texas Orthopedics in Austin, Texas, knows that deciding on whether to operate on an obese person can be tricky for a surgeon and that pre-operative planning is essential for determining best patient outcomes.

He recently discussed the challenges an obese patient presents when it comes to direct anterior approach total hip arthroplasty (THA) and how the benefits and risks of doing the surgery have to be carefully weighed.

Goldberg said first, you have to recognize the difficult patients. During the pre-operative stage, you need to be able to identify both ideal and difficult patients. Besides obesity, hip type, previous hardware and deformities could also put a wrench into the situation, so it is important to recognize all these challenges right from the beginning, so you make an informed decision.

He also said that you need to be honest about knowing your own limits. Can you do this surgery safely and accurately utilizing the direct anterior approach?

When it comes to surgery logistics, Goldberg said the most difficult patients early in the learning curve for the direct anterior approach are those with a muscular, short, varus hip; obesity and big tensor fasciae latae (TFL).

During the preoperative evaluation, he recommends that you identify these patient characteristics to properly determine which will be ideal candidates and which will be difficult patients.

According to Goldberg an ideal candidate for the direct anterior approach early in the surgeon’s learning curve is a thin, valgus female with soft, pliable muscles and no other pathology, while a difficult patient is an obese patient who has a short varus neck and may have protrusion (ankyloses), severe deformities and/or hardware from previous surgeries.

He said that it is best to avoid the difficult patients early in your learning curve, pointing to studies that show higher complication and infection rates in obese patients.

In one study he referenced, “Complication Rates After Hip or Knee Arthroplasty in Morbidly Obese Patients,” the authors reviewed 12,355 patients, comparing those with a BMI greater than 40 to those with a BMI less than 40. They found no change in venous thromboembolism or bleeding, but an increase in erythema, peripheral edema, diarrhea and gastrointestinal or abdominal pain, wound inflammation or infection and respiratory tract or lung infections.

Other studies have shown a higher use of OR time, anesthesia induction and surgery time as well as a higher risk of infection during primary THA the more obese a patient is.

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.

Goldberg’s Surgical Approach

“Obesity is not a contraindication, but I don’t do surgery on patients with a BMI greater than 40,” Goldberg explained. “And if you have a metabolic syndrome or components of it, your BMI has to go below 35.”

He added, “Then I identify where do you carry your obesity? Is it in your trunk or limbs? A patient who carries all their weight in their abdomen is easier to do. You can simply tape it up and get to the relatively thin hip.”

In his opinion, obesity is not predictive of the operative struggle, their TFL is. Big patients with big tensor muscles are the patients he predicts to be difficult in the OR.

“With every patient I ask, is this patient amenable to the anterior approach?” he said. “Preoperative planning is essential. And when you see hardware you have to ask yourself, does it need to be retrieved and can it be retrieved from the front?”

“And if it can, you can go from the front, but if you can’t, think about getting a CT scan. A CT scan can be vitally important to determine if you can take an anterior approach.”

If you decide to proceed with a direct approach THA with a difficult patient, Goldberg said that a generous femoral release is very important. Femur exposure is the key to successful, stress-free anterior surgery.

He explained that there are two restraints when it comes to releasing the femur. One is the pubofemoral ligament, the other is the ischiofemoral ligament.

“Those of us who are true believers in delivering the femur all the way forward will release both of these ligaments in their entirety. We are not releasing the piriformis or the obturator externus, but we are releasing these two pretty much every time.”

He added that with deformities, you also need to plan out using special implant techniques. You need to consider whether you need to do an osteotomy of the femur or sink the stem very low to preserve their leg length. You also need to consider if they have hardware from a previous surgery. You need to ask yourself, is there an alternative stem design or stem position that will allow you to proceed with the case from the front.

“Pre-operative planning is essential so you can identify ideal and difficult patients and do x-ray planning. Attention to surgical details can make for a well-executed and successful THA,” Goldberg emphasized.

Meet Dr. Goldberg at the Upcoming Direct Anterior Approach Hip Course

Goldberg’s presentation, “How to Handle Obese, Muscular, and Other Challenging Patients” was originally presented at the International Congress for Joint Reconstruction’s 2017 6th Annual Direct Anterior Approach Hip Course.

His presentation on handling obese patients is also on the agenda for the 7th Annual Direct Anterior Approach Hip Course from the International Congress for Joint Reconstruction which will be held September 27-29, 2018 in Houston, Texas.

The conference is designed for orthopedic surgeons and allied health professionals looking to learn the latest in orthopedic technology and optimum patient care when using the direct anterior approach to hip arthroplasty.

To register, click here.