Background:
Oral bisphosphonates comprise the most widely prescribed class of antiosteoporotic drugs. Recent reports, however, propose a link between prolonged bisphosphonate use and atypical, low-energy, subtrochanteric fractures.
Objectives:
The aim was to describe the clinical course of a patient treated long-term with alendronate who developed subtrochanteric stress fractures and to propose a hypothesis to explain teriparatide's potential contribution in healing the patient's stress fractures.
Results:
Magnetic resonance imaging (MRI) showed classical bilateral stress fractures of the mid-femora. Baseline serum 25-hydroxyvitamin D3 was low; bone-specific alkaline phosphatase was slightly increased; serum carboxyterminal cross-linking telopeptide of bone collagen and urine aminoterminal cross-linking telopeptide of bone collagen were low to normal, as was serum osteocalcin. Dual-energy x-ray absorptiometry showed osteopenic vertebral bone mineral density and osteoporotic hip values. Treatment with large doses of oral vitamin D increased serum 25-hydroxyvitamin D3 to normal within 2 months, after which it remained in the normal range with maintenance doses. Thigh pain, present as an initial symptom, intensified, and the MRI appearance of the fractures worsened. Teriparatide treatment commenced, and 6 months later, a repeat MRI showed decreased edema at the fracture sites with faint cortical bridging. Thigh pain and lower limb weakness disappeared over the next year, and complete fracture healing was established (MRI).
Conclusions:
Based upon the chronology of fracture healing in our patient and published evidence that teriparatide heals stress fractures in a rat model, we think that teriparatide was probably primary in this patient's positive response to therapy, with calcium, vitamin D therapy, and alendronate discontinuation playing secondary roles.
Vitamin D and Fracture Healing: An Ongoing Puzzle