What anabolic agents are recommended for a patient undergoing back surgery to enhance bone formation and reduce fracture risk?

Anabolic Agents for Pre-Surgical Back Surgery Patients

For patients with osteoporosis undergoing spinal instrumentation surgery, preoperative teriparatide should be strongly considered to reduce postoperative complications including screw loosening and improve fusion rates. 1

Primary Recommendation: Teriparatide

Teriparatide (recombinant PTH 1-34) is the recommended anabolic agent for osteoporotic patients preparing for back surgery with instrumentation. 1 The Congress of Neurological Surgeons provides Grade B evidence supporting preoperative teriparatide to decrease postoperative adverse events, including screw loosening and delayed or lower fusion rates. 1

Evidence Supporting Teriparatide in Spine Surgery

• Fusion rates are significantly higher with teriparatide: In osteoporotic postmenopausal females undergoing instrumented fusion, teriparatide achieved 82% fusion rate at 8 months compared to 68% at 10 months with bisphosphonates (risedronate), with earlier time to fusion. 1

• Screw loosening is reduced: Teriparatide demonstrated only 7% incidence of pedicle screw loosening compared to 13% with bisphosphonates and 15% in untreated controls. 1

• Bone mass increases are superior: Teriparatide was associated with increased bone mass compared to bisphosphonates in the perioperative spine surgery population. 1

Dosing and Administration

• Standard dose: 20 mcg daily subcutaneous injection 2, 3
• Treatment duration: 18-24 months maximum 3
• Timing: Should be initiated preoperatively and continued through the perioperative period 1

Alternative Anabolic Agents

Abaloparatide (PTHrP analog)

Abaloparatide is an appropriate alternative for very high fracture risk patients, though specific spine surgery data is limited. 4

• Efficacy: Reduces vertebral fractures by 86% and nonvertebral fractures by 43% at 18 months 5
• BMD improvements: Increases lumbar spine BMD by 9.2% and total hip BMD by 3.4% at 18 months 5
• Dosing: 80 mcg subcutaneous injection once daily 5

Romosozumab (Sclerostin Inhibitor)

Romosozumab should be used with caution and only in patients intolerant of other agents due to cardiovascular concerns. 4

• Dual mechanism: Increases bone formation while simultaneously decreasing bone resorption 6
• Efficacy: Reduces vertebral fractures by 13 per 1000 patients and clinical fractures by 9 per 1000 patients 4
• Cardiovascular risk: Associated with increased myocardial infarction, stroke, and death, making it conditionally recommended only when other agents cannot be used 4

Critical Contraindications for Anabolic Agents

Absolute contraindications that preclude use in spine surgery patients:

• Prior radiation therapy involving the skeleton - this is particularly relevant for spine surgery patients who may have had prior radiation 1, 4
• Bone metastases or skeletal malignancies 1, 4
• Paget's disease of bone 1, 4
• Open epiphyses 1, 4

The theoretical concern about osteosarcoma risk has not been substantiated - a study of 200,000 patients showed no significant difference in osteosarcoma incidence between teriparatide-treated patients and the general population. 1

Mandatory Sequential Therapy

Critical pitfall: Discontinuing anabolic agents without follow-up antiresorptive therapy results in rapid bone loss and increased fracture risk within 12-18 months. 4

After completing anabolic therapy, immediately initiate:

• Bisphosphonates (preferred) 4
• Denosumab (acceptable, but must be followed by bisphosphonate when discontinued) 4

Bisphosphonates Alone: Insufficient Evidence

There is insufficient evidence to support bisphosphonates alone for reducing postoperative adverse events in spine surgery patients with osteoporosis. 1 While bisphosphonates are effective for general osteoporosis treatment, they lack the anabolic bone-forming properties needed to optimize surgical outcomes in instrumented spine procedures. 1

Patient Selection Algorithm

Use anabolic agents preoperatively if patient meets ANY of these criteria:

• Undergoing spinal instrumentation with osteoporosis (primary indication) 1
• BMD T-score ≤ -3.5 4
• Recent fracture within past 12 months 4
• FRAX 10-year risk: major osteoporotic fracture ≥30% OR hip fracture ≥4.5% 4
• Multiple prior osteoporotic fractures 4
• High-dose glucocorticoids (≥30 mg/day for >30 days or cumulative ≥5 g/year) 4