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Although scales and skin fold calipers are easy to use, they may not be the best indicators of obesity.
Courtesy of thinkstock

AAOS Now

Published 5/1/2013
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Mary Ann Porucznik

Obesity Epidemic Has Impact on Specialty Care

Excess weight presents problems for pediatric, spine patients

The impact of obesity on surgical and nonsurgical treatment outcomes can be seen in every orthopaedic specialty. At the AAOS Now-sponsored forum on “Obesity, Orthopaedics, and Outcomes,” held March 18 in Chicago, orthopaedic surgeons and other experts noted that the problems associated with obesity can begin in childhood and last throughout a person’s life.

112 pounds, 4 years old
According to Steven L. Frick, MD, chair of the department of orthopaedic surgery at Nemours Children’s Hospital in Orlando, Fla., the effects of obesity on the growing skeleton can literally shape a child’s life. “Obese children become obese adults,” he said.

In many areas of the country, societal, economic, and cultural factors contribute to the increasing number of obese children, but, noted Dr. Frick, growth charts can be used to help differentiate between the big-boned, muscular child and the obese child.

He pointed out that obese children tend to have more fractures as well as conditions such as slipped capital femoral epiphysis (SCFE), Blount’s disease, and other medical complications and that their fractures are harder to treat and may require different implants.

Dr. Frick provided an example of a 4-year-old boy who weighed 112 pounds (Fig.1). The child had Blount’s disease with both varus and internal rotation deformities and required an oblique plane osteotomy—a “relatively large surgery for a biomechanical disorder.” He pointed out that flexible nailing may not be appropriate for children with femur fractures who weigh more than 100 pounds.

Because tension accelerates and compression slows growth across the growth plate, progressive valgus or varus malalignment may develop in obese children. Left untreated, for example, Blount’s disease may lead to joint subluxation, end-stage arthrosis, and joint replacement before the age of 30 or 40.

“As physicians, we have an opportunity to do something, not only on a one-on-one basis with the patient before surgery, but also on a larger, public health basis,” said Dr. Frick. “As orthopaedic surgeons, we must remember that we are physicians for the whole patient. We need to educate all practitioners who treat children that knee pain equals hip pain. We need them to think about SCFE when an obese child complains of lower extremity pain. We need to talk to parents because most obesity isn’t due to endogenous causes such as Cushing syndrome but to exogenous causes, such as poor food choices and lack of exercise.”

The pediatric spine
Coming from the “biscuit and barbecue belt,” Jeffrey R. Sawyer, MD, who specializes in pediatric orthopaedics and spine surgery at the Campbell Clinic in Memphis, Tenn., noted that the pediatric obesity epidemic is worse in southern states and accounts for approximately 300,000 deaths each year.

Most studies on the impact of obesity in the pediatric spine focus on adolescent idiopathic scoliosis (AIS) patients. In one study on bracing, for example, obese patients had higher complication rates and lower success rates; the progression to surgery was almost double among overweight patients than among normal weight patients. “Bracing compliance for obese patients is difficult, as with any AIS patient,” said Dr. Sawyer, “and some centers see obesity as a contraindication for bracing.”

Results for AIS patients who are treated surgically are mixed. Although one study found “no differences,” a closer look at complications, noted Dr. Sawyer, showed that overweight patients had higher rates of implant failure, pseudarthrosis, and surgical revision. The increased weight on open growth plates may be one reason for a higher incidence of kyphosis among overweight AIS patients.

A recent study found that obese patients who underwent surgery for AIS had longer surgical times and greater blood loss than normal weight patients; they also had a higher risk of surgical site infections. “If we’re not using weight-based antibiotic dosing, we may be underdosing these patients,” he suggested.

Dr. Sawyer said that a high-risk anesthesia clinic might be helpful in identifying and preparing patients with a body mass index (BMI) of 35 or higher and their parents for possible complications. He called for additional investigations on the impact of obesity, particularly with regard to infection, short- and long-term outcomes, complications, and cost.

Although scales and skin fold calipers are easy to use, they may not be the best indicators of obesity.
Courtesy of thinkstock
Fig. 1 This 4-year old boy, who weighed 112 lbs., required an oblique plane osteotomy to treat his Blount’s disease.
Courtesy of Steven L. Frick, MD, and Nemours Children’s Hospital, Orlando, Fla.
Fig. 2 Sagittal T1-weighted cervical MRI demonstrating the measurement of the morphometric parameters. Reprinted with permission from Mehta AI, Babu R, Sharma R, Karikari IO, Grunch BH, Owens TR, et al: Thickness of Subcutaneous Fat as a Risk Factor for Infection in Cervical Spine Fusion Surgery. J Bone Joint Surg Am, 2013;95(4):323-328. doi: 10.2106/JBJS.L.00225

The adult spine
Kris Radcliff, MD,
assistant professor in the department of orthopaedic surgery at the Rothman Institute in Philadelphia, begin his presentation by examining the relationship between obesity and spinal disk degenerative disease. The first of two European population-based studies cited by Dr. Radcliff found that obesity increased the incidence of radiating lower back pain; when obesity was combined with low activity levels, the odds of low back pain nearly doubled.

The impact of early obesity could be seen in the second study, which looked at overweight adolescents. The study, which had a 28-year follow-up, found that being overweight as a teenager increased an individual’s risk of later spine surgery (odds ratio: 7.1). “The data are compelling,” said Dr. Radcliff. “Just as weight increases pressure on contact points in the knee and hip, leading to degenerative joint disease, obesity can predispose a person to spinal degenerative disk disease.”

Similarly, weight loss leads to less back pain. Studies on the impact of bariatric surgery and medically supervised weight loss found that a significant reduction in weight correlated with a reduction in the Oswestry Disability Index and back pain.

“Intriguingly, MRI measurements also showed an increase in disk height after bariatric surgery,” said Dr. Radcliff. “Perhaps loading the spine does cause some reduction in disk height; if you can reduce the patient’s body weight, you can then increase the disk height.”

With regard to perioperative complications, Dr. Radcliff noted that studies have shown that obese patients have longer surgical times and generally higher rates of complications (infection, wound dehiscence, thromboembolic disease, myocardial infarction, and readmission) than nonobese patients. However, he also pointed out that the location of adipose tissue, rather than the patient’s BMI, may pose a greater risk for surgical site infection.

“This makes sense,” he said. “You’re operating through the adipose tissue, and with more dead space, there’s more risk of infection. In a population of patients undergoing posterior cervical laminectomy and fusion in a single center, it was the distance from the skin to the lamina (Fig. 2) or the distance from the skin to the fascia that were the risk factors for infection, not BMI.”

To reduce the risk of perioperative complications in obese patients undergoing spine surgery, Dr. Radcliff recommended the following techniques:

  • Minimally invasive surgery—it’s technically possible and studies have shown benefits similar to open surgery. However, fluoroscopy is difficult in an obese patient, so this should be limited to experienced surgeons.
  • Use percutaneous techniques, even in trauma patients, to avoid the significant morbidity resulting from a long, posterior approach. It may be challenging, but it is possible.
  • Pay careful attention to closing the adipose tissue/subcutaneous fat to reduce the risk of surgical site infection. Don’t allow a large gap of fluid space; the pocket will result in drainage.
  • Consider using an incisional vacuum to further close that dead space; although no data support the use of an incisional vacuum in spine surgery, data in other orthopaedic applications are encouraging.
  • In open surgery, depending on the amount of subcutaneous skin, a longer incision that permits more retraction from the midline may be needed.

Dr. Radcliff also addressed the results of spine surgery in obese patients. He noted that nonobese patients had less pain and better scores after surgery for lumbar spinal stenosis than obese patients, but “the change in outcome, the treatment effect of surgery, is unchanged in obese versus nonobese patients.

“As a surgeon,” he continued, “if I were to have a patient who is obese or morbidly obese and looking for lumbar spine surgery, I could tell that patient that he or she would benefit from the decompression, but still be at a higher risk of complications.”

Mary Ann Porucznik is managing editor of AAOS Now. She can be reached at porucznik@aaos.org

Editor’s Note: This is the second in a series of articles on the AAOS Now-sponsored forum, “Obesity, Orthopaedics, and Outcomes,” held on March 18, 2013, in Chicago. The first article, “Obese Patients Present a Weighty Problem,” was published in AAOS Now, April issue.

A copy of the agenda book including selected abstracts on the issue of obesity and orthopaedics is available on request. Email aaoscomm@aaos.org