There are different reasons why patients with chronic low back pain need lumbar spinal fusion. Lumbar canalstenosis (narrowing of the spinal canal), degenerative disc disease, scoliosis, and instability after a previous (laminectomy) surgery are the most common problems. Laminectomy refers to the removal of a section of vertebral bone called the lamina. Cutting away the bone helps take pressure off the spinal cord or spinal nerve roots.
Most of these conditions are not the direct result of being overweight or even obese. Some of the symptoms from these conditions such as back pain can be made worse by being obese. Weight loss before surgery and quitting smoking for those who smoke are always advised. In fact, some surgeons insist on it.
Anyone with a body mass index (BMI) of 30 or higher requires careful consideration and monitoring when having surgery. A person’s BMI can be calculated using a mathematical equation of the ratio between height and weight. Anyone with a BMI of 30 kg/m2 or higher is classified as obese.
Morbidly obese is a separate category for those individuals who are 20 per cent or more above the optimal weight for their height and body type. Their BMIs can exceed 40 kg/m2. Patients with a lower BMI (35 to 40 kg/m2) can also be considered morbidly obese if they have one or more significant comorbidities. Comorbidity refers to other health problems such as diabetes, heart disease, high blood pressure, asthma, sleep disorders, and so on.
The surgeon must go into the lumbar spinal fusion procedure with the knowledge that obese patients have a greater risk of postoperative complications. However, there is some evidence that these problems may not be related to body size as much as the number of segments being fused. Fusion of one or two vertebrae isn’t nearly as risky as five or six segments being fused. Overall results may be better if the obese or morbidly obese patient has bariatric surgery first before spinal surgery.