A Case of Teriparatide Use in Nonunion Atypical Ulnar Fracture

Abstract

Background: Atypical upper limb fracture is a rare complication of bisphosphonate use. The management of nonunion fractures is challenging, especially in patients who are not surgical candidates. Teriparatide, a novel anabolic drug for osteoporosis has been increasingly used off-label for treatment of nonunion fractures and bisphosphonate related atypical fractures of the lower extremity. The proposed mechanism of healing is by enhancement of callus formation and mechanical strength. Clinical Case: A 72 year-old woman with a history of bilateral lower extremity paralysis and bilateral upper extremity paresis, who mobilized short distances with Canadian crutches, had been treated for 15 years with alendronate, for osteopenia associated with multiple risk factors for osteoporosis. 11 months before referral, and a month after alendronate was discontinued, she sustained a muscle-spasm induced fracture of the mid-shaft of the right ulna. She was treated nonoperatively due to chronic osteomyelitis with recurrent bacteremia from a prior non-healing left ulnar fracture (with internal fixation). Bone density of the right forearm had been normal. Since the right ulna break was transverse with minimal comminution, located in the diaphysis, occurred after trivial force and exhibited delayed healing, it was thought to be an atypical fracture secondary to bisphosphonates. She was initiated on cyclical teriparatide injection 20 mcg subcutaneously daily, with 2 months on and 2 weeks off. In one year, patient responded with dramatic radiographic improvement by forming a large callus with almost complete healing of the fracture. Conclusion: Mid-forearm atypical fracture from long-term bisphosphonate use is rare and is at risk for nonunion. The management of atypical upper limb nonunion fracture in nonoperative patients is not well established. Case reports exist of patients with atypical upper limb fracture who are either treated conservatively, or surgically with fixation/bone grafting +/- teriparatide. Our case showed that teriparatide, when used cyclically, exerted positive osteogenic effect and improved healing of the nonunion of an atypical fracture of forearm in a patient who continued weight bearing activity on her only functional limb.