The Effect of Extreme Obesity on Spinal Fusions

Back pain is no stranger in the adult world. Being overweight is a definite risk factor for back pain associated with spinal degeneration. Surgery in the form of spinal fusion may benefit obese patients but is also linked with higher complication rates. In this study from California, researchers look at the effect of morbid obesity on complications and complication rates.

Obesity is defined by a body mass index (BMI) of 30 or greater. Morbid obesity is determined by a BMI of 40 or more. The BMI is a measure of body fat based on height. It isn’t the only way to identify obesity but it is a quick and easy method to get a general idea of relative sizes.

California has a database with information on every patient who goes into the hospital anywhere in the state. Information is collected on a broad range of patient demographics such as age, gender, race, insurance coverage, and procedure performed. Patient body weight is another variable entered into the database. Using this database, the researchers were able to find 1,455 morbidly obese patients who had spinal fusion surgery.

The type of surgery was divided into four groups: cervical and lumbar fusions and anterior or posterior approach for those two locations. Total time in the hospital, total costs, and all complications were also recorded and available for comparison among the four groups. They found that morbid obesity was, in fact, the single most significant predictor of postoperative complications.

The rate of complications among the morbidly obese was 97 per cent higher than among patients of normal weight. That high rate was consistent for all types of postoperative problems (e.g., heart attacks, blood clots, pneumonia, infections). Fortunately, the death rate was not higher in those who were morbidly obese. Overall costs were increased by 28 per cent. Older age combined with morbid obesity resulted in even higher complication rates.

With an ever increasing number of overweight and morbidly obese people, surgeons can expect to see more problems with spinal degeneration requiring surgical treatment. Understanding the risks and costs to the health care system is an important way to reduce these features.

The authors are not suggesting that morbidly obese individuals should not have spinal fusion. On the contrary, these folks seem to benefit as much as adults who are not obese. The main idea from these findings is the need to reduce patient risks when pre-operative weight loss is not an option.

One other finding from this study that deserves further attention is the fact that wound complications (the number one postoperative problem) were equally present among all patients suggesting the need to address that issue first and foremost. Other future studies may need to compare risks and costs associated with open incision spinal fusions and arthroscopic mini-invasive approaches for this particular group of patients.