Open-label Clinical Trial of Alendronate After Teriparatide Therapy in People with Spinal Cord Injury and Low Bone Mineral Density

Study Design: Non-randomized open-label clinical trial of oral alendronate after teriparatide therapy in people with spinal cord injury (SCI) and low bone mineral density (BMD).

Objectives: To determine if alendronate would prevent bone loss after discontinuation of teriparatide.

Setting: Outpatient research clinic at Northwestern University Feinberg School of Medicine.

Methods: Seventeen participants with chronic SCI who recently completed 12-24 months of teriparatide treatment received oral alendronate 70 mg once weekly for 12 months. Participants were evaluated at baseline, 6 months and 12 months. Bone was assessed by: DXA at the spine and hip, CT at the distal femur/proximal tibia, serum collected for bone markers, and bone strength determined by finite element (FE) analysis of the proximal tibia.

Results: Areal BMD showed no significant change from baseline at the total hip or femoral neck, where mean change (SD) was 1.3% (4.7) and 0.54% (5.0), respectively. However, areal BMD increased significantly at the spine by 2.5% (4.6). CT demonstrated significant increases in bone mineral content at the femoral epiphysis, metaphysis, and diaphysis, 15% (18), 7.7% (12), and 3.0% (3.5), respectively. Measurements at the tibia illustrated improvements and reductions, but no changes to FE-predicted strength were observed. Biomarkers illustrated inhibition of bone formation and resorption, with P1NP and CTX decreasing by 52% (82) and 62% (74), respectively.

Conclusion: Twelve months of alendronate after discontinuation of teriparatide in people with SCI can prevent bone loss and may increase bone mass and preserve bone strength at the spine, hip, and some sites of the knee.