Effect of teriparatide (PTH 1–34) on fusion mass and clinical outcomes the year after single-level instrumented posterolateral fusion

BACKGROUND CONTEXT: Successful spine fusion requires formation and remodeling of new bone. For this reason, osteoporosis is a risk factor that affects fusion in spine surgery. Parathyroid Hormone (PTH) is an anabolic drug that increases activity of osteoblasts and osteoclasts. Some studies have demonstrate the PTH accelerates the lumbar posterolateral fusion in osteoportic patients, but the clinical and functional impact of these medication is not well known PURPOSE: To study the influence of the treatment with Teriparatide in the fusion mass and clinical outcome in a group of patients with osteoporosis and a lumbar posterolateral fusion during a 1-year follow-up. METHODS: Seventy-two patients underwent a L4-L5 instrumental posterolateral fusion using pedicle screws and bone graft. Patients were divided into 2 groups: Treated with teriparatide (20µg/day, post-surgery, during 1 year) n= 47, or not treated n=25. Patients were studied before surgery and 3 months, 6 months and 1 year after surgery. The following assessments were performed: quality of bone fusion mass and clinical outcome evaluated by visual analogue scale score (VAS) and Oswestry Disability Index (ODI). RESULTS: Radiographically, a decrease on the volume of fusion mass is observed in all cases, but this decrease was significantly lower in the group of patients treated with PTH. All patients have a significant improvement in pain and function. No differences in the improvement were observed between both groups. CONCLUSIONS: A decrease on fusion mass volume was observed in all cases, but patients on Teriparatide treatment had a better fusion mass volume development. However, these radiological differences did not influence on clinical outcome at 1 year follow-up, as both groups present the same improvement.