Bariatric bypasses contribute to loss of bone mineral density but reduce axial back pain in morbidly obese patients considering spine surgery

BACKGROUND: Many spine surgeons recommend stringent weight loss, including bariatric bypass procedures, prior to “elective” spine surgery (should not be for axial back pain alone) in morbidly obese patients (defined by a body mass index (BMI) of >40 mg/kg(2) or >35 mg/kg(2) with two or more major comorbidities) to reduce their greater risk for major perioperative complications. Although bypasses typically lead to marked weight reduction and even reduced axial back pain, they also promote unrecognized and often insufficiently treated vitamin D deficiency and loss of bone mineral density. METHODS: Morbidly obese patients who are under consideration for “elective” spine operations (other than for back pain alone) are often told to lose weight. Some choose to undergo bariatric bypass procedures, but are unaware of the potential risks/complications of these procedures. RESULTS: Within the first 2 years following most bariatric bypass procedures, patients experience not only marked loss of weight and muscle mass, but also significant vitamin D deficiency and loss of bone mineral density, increasing their susceptibility to fractures. Nevertheless, some patients also experience a sufficient reduction of axial back pain to avoid spinal surgery. CONCLUSIONS: Morbidly obese patients under consideration for “elective” spine surgery may undergo bariatric bypass procedures that lead to a significant reduction of vitamin D levels and loss of bone mineral density. However, potential benefits may include a sufficient reduction of axial back pain to avoid surgery in a select subset of patients altogether.