Review Question - QID 220563

The patient presents with symptoms of lumbar spine stenosis secondary to adult spinal deformity as well as osteoporosis, as suggested by her history of multiple fragility fractures. Treatment of the osteoporotic patient with teriparatide for at least 6 months before corrective adult spinal deformity surgery is associated with lower rates of reoperation and pseudarthrosis (Answer 2).

Osteoporosis is a disorder most commonly seen in elderly women. It is characterized by diminished bone mineral density that places patients at a higher susceptibility to fragility fractures (fractures occurring from forces that would not usually cause a fracture). A Dual Energy X-ray Absorptiometry (DEXA) scan with a T-score greater than 2.5 standard deviations below the mean bone mineral density of a young adult is the gold standard for diagnosis. Osteoporosis is a known risk factor for reoperation and pseudarthrosis, two major complications of corrective adult spinal deformity surgery. Teriparatide is a recombinant human parathyroid hormone used in patients with osteoporosis that functions through osteoblast stimulation to improve bone mineral density. Its use in osteoporotic patients before adult spinal deformity surgery has been found to be associated with decreased rates of reoperation and pseudarthrosis.

Mohanty et al. performed a retrospective review of 540 patients undergoing adult spinal deformity surgery to assess the impact of preoperative teriparatide administration on the postoperative outcomes of osteoporotic patients. They noted in their matched cohort analysis that osteoporotic patients treated with teriparatide before surgery had a lower rate of reoperation (11.5% vs 23.1%), lower rate of pseudarthrosis (6.4% vs 21.8%), and comparable rates of minimally clinically important differences achieved. They concluded that teriparatide administration in osteoporotic patients is associated with improved rates of reoperation, lower rates of pseudarthrosis, and equivalent patient-reported outcomes compared to non-treated osteoporotic patients also undergoing adult spinal deformity surgery.

Gupta et al. performed a retrospective analysis of 399 patients who underwent surgery for adult spinal deformity to characterize the incidence and timing of revision surgery in patients with or without osteoporosis. They found a higher reoperation rate in osteoporotic patients compared to non-osteoporotic patients (40.5% vs 28.0%) and that these revision surgeries occurred at similar time frames in both groups. They concluded that the underscoring of osteoporosis as a risk factor for sub-optimal outcomes in adult spinal deformity surgery warrants the development of interventions to improve patient bone health preoperatively.

Varshaneya et al. performed a retrospective analysis of 2564 Medicare patients who underwent adult spinal deformity surgery to assess the impact of osteoporosis on postoperative outcomes in this particular patient population. They found that patients with osteoporosis had higher odds of reoperation at 1- (OR: 1.4) and 2-year (OR: 1.5) time points as well as higher odds of 90-day readmission (OR: 1.3). They concluded that the prevalence of osteoporosis in their particular population and the impact that it has on outcomes necessitates improved implant design for those with poor bone quality and better incorporation of healthy dietary and exercise regimens.

Figures A and B are radiographs of a lumbar spine with significant degenerative disease as well as deformity in the coronal and sagittal planes.

Incorrect Answers:
Answer 1: Patients who smoke have a higher, not lower, risk of reoperation and pseudarthrosis.
Answer 3: A thoracolumbar cobb angle greater than 20 degrees is a described risk factor for pseudarthrosis. A thoracolumbar cobb angle of 15 degrees does not fall within this range.
Answer 4: The patient’s most recent DEXA scan confirms a diagnosis of osteoporosis consistent with the patient’s history of multiple fragility fractures. This information reiterates that the patient is at a higher, not lower, risk of pseudarthrosis and reoperation.
Answer 5: A recent cohort study comparing osteoporotic patients undergoing spinal surgery who were treated with teriparaptide or bisphosonate preoperatively demonstrated that those treated with teriparatide had superior fusion rates and lower rates of implant failure compared to those treated with bisphosphonates.