In an adult patient with osteoporosis undergoing spinal surgery, should teriparatide (Forteo) be continued during and after the operation?

Should Forteo Be Continued During and After Spine Surgery?

Yes, teriparatide (Forteo) should be continued and ideally initiated immediately after spine surgery in osteoporotic patients undergoing spinal instrumentation, as it significantly improves fusion rates, reduces screw loosening, and decreases vertebral fractures compared to bisphosphonates or no treatment.

Primary Recommendation

The Congress of Neurological Surgeons provides Grade B evidence recommending that clinicians should consider preoperative teriparatide in patients with osteoporosis undergoing spinal instrumentation to decrease postoperative adverse events, including screw loosening and delayed or lower fusion rates 1. However, the evidence actually supports continuation through the perioperative period and postoperatively.

Timing and Duration Strategy

Perioperative Use

• Start immediately postoperatively if not already on treatment - Studies demonstrate that teriparatide initiated within 1 week after surgery effectively reduces screw loosening and improves fusion 2, 3
• Continue if already on treatment preoperatively - Perioperative administration (before and after surgery) shows superior outcomes compared to bisphosphonates 4
• Do not stop during surgery - There is no evidence suggesting interruption benefits patients, and continuous therapy optimizes bone healing

Treatment Duration

• Minimum 6 months postoperatively - Critical period for fusion and screw stability 2
• Up to 2 years total lifetime use per FDA labeling 5
• Consider the 2-year lifetime limit when planning treatment, reserving it for high-risk fracture periods including the surgical healing phase

Evidence Supporting Continuation

Fusion Outcomes

Teriparatide demonstrates 2.15-fold higher fusion rates compared to non-teriparatide groups (OR 2.15,95% CI 1.56-2.97) 6. Specifically:

• 2.12-fold higher fusion vs bisphosphonates (OR 2.12,95% CI 1.45-3.11) 6
• 2.23-fold higher fusion vs placebo (OR 2.23,95% CI 1.22-4.08) 6
• Fusion achieved at 8 months with teriparatide vs 10 months with bisphosphonates (82% vs 68% fusion rate) 1

Hardware Complications

• Screw loosening reduced to 7% with teriparatide vs 13-15% with bisphosphonates or no treatment 1
• Postoperative teriparatide shows significantly lower screw loosening during 6-12 months (2.3% vs 9.2% with bisphosphonates, p<0.05) 2
• Vertebral-failure-type proximal junctional kyphosis reduced from 15.2% to 4.6% (p=0.02) 7

Bone Quality Improvements

• Volumetric BMD increases at the vertebra above instrumentation (UIV+1) from 326 to 366 mg/cm³ 7
• Trabecular bone thickness increases by 14% and trabecular number by 5% 7
• Subsequent vertebral fractures reduced by 84% (OR 0.16,95% CI 0.06-0.41) 6

Dosing Per FDA Label

• 20 mcg subcutaneously once daily 5
• Administer into thigh or abdominal region
• Initial doses should be given where patient can sit/lie down due to orthostatic hypotension risk 5
• Supplement with calcium (500 mg/day) and vitamin D (1000 IU/day) 5, 2

Critical Contraindications and Precautions

Do NOT use teriparatide if:

• Open epiphyses (pediatric patients)
• Paget's disease or other metabolic bone diseases
• Prior skeletal radiation therapy
• History of bone metastases or skeletal malignancies
• Underlying hypercalcemic disorders 5

Monitor for:

• Transient hypercalcemia - particularly relevant with digoxin use 5
• Orthostatic hypotension - especially with initial doses 5
• Active or recent urolithiasis - may be exacerbated 5
• Asymptomatic alkaline phosphatase elevation - less common but documented 8

Comparison to Bisphosphonates

Bisphosphonates are inferior for surgical patients - The CNS guideline states there is insufficient evidence to support bisphosphonates alone in patients undergoing spinal instrumentation (Grade Insufficient) 1. Key differences:

• Bisphosphonates may delay fusion in the first 6 months postoperatively 1
• Teriparatide shows earlier fusion and higher rates across all timepoints 1
• Screw loosening rates with bisphosphonates (13%) approach control group rates (15%) 1

Clinical Algorithm

For osteoporotic patients undergoing spine surgery:

1. If already on teriparatide preoperatively → Continue through surgery and for minimum 6 months postoperatively (up to 2-year lifetime limit)

2. If on bisphosphonates preoperatively → Consider switching to teriparatide immediately postoperatively for superior fusion outcomes

3. If treatment-naïve → Initiate teriparatide within 1 week postoperatively, continue for 6-12 months minimum

4. All patients → Ensure calcium and vitamin D supplementation throughout treatment period

Common Pitfalls to Avoid

• Do not stop teriparatide perioperatively - No evidence supports interruption, and continuous therapy optimizes outcomes
• Do not rely on bisphosphonates alone for surgical patients - Insufficient evidence for benefit 1
• Do not exceed 2-year lifetime use - FDA limitation based on osteosarcoma risk in animal studies 5
• Do not forget supplementation - Calcium and vitamin D are essential adjuncts 5, 2
• Do not use in patients with prior skeletal radiation - Absolute contraindication due to osteosarcoma risk 5

The evidence strongly supports continuation and postoperative initiation of teriparatide in osteoporotic patients undergoing spine surgery, with superior outcomes in fusion rates, hardware stability, and prevention of subsequent fractures compared to all alternatives.