Treatment of Bisphosphonate Associated Atypical Femur Fracture with a Combination of Teriparatide and a Novel Surgical Technique

Introduction:
Atypical femur fractures (AFF) caused by long term Bisphosphonate use are associated with high rates of delayed healing and non-union, posing a significant challenge in the management of these patients.

Case Description:
We describe the case of a 64-year-old female with osteopenia on Bisphosphonate therapy for 15 years who sustained a displaced left AFF following a fall from standing height. She reported a 6-month history of antecedent left groin pain. Radiographs of the left femur showed an acute displaced transverse diaphyseal fracture with lateral cortical thickening and beaking. The right femur radiograph showed features of abnormal cortical remodeling with thickened, irregular cortices. DEXA showed T-scores of -2.1 at the left femoral neck, -1.4 at the left total hip, and -1.4 at the lumbar spine.

She underwent an open reduction and internal fixation with insertion of a cephalomedullary nail placed in compression mode. A novel technique of intraoperative removal of the endosteal hypertrophied cortical bone at the fracture with a Midas rex cutting burr was used and there was excellent cortical contact after reduction. She had immediate relief of her pain and was permitted to fully weight-bear postoperatively. Her bisphosphonate was stopped immediately and Teriparatide was initiated at 7 weeks post-operatively. Radiographs 8 weeks after initiation of Teriparatide showed evidence of normal fracture union with mature callus formation.

Discussion:
AFF caused by prolonged Bisphosphonate use have a high rate of delayed healing and non-union due to abnormal bone remodeling. Use of Teriparatide post-operatively has been shown to reduce healing time in recent small studies in surgically treated patients. Our case demonstrates expedited healing time when Teriparatide was combined with a novel surgical technique involving removal of a portion of the abnormal fracture end and placement of an intramedullary nail in compression mode.

Furthermore, the patient had radiographic evidence of cortical thickening on her right femur, increasing her risk for contralateral AFF. Prophylactic surgical stabilization was recommended but the patient has deferred this. She remains fracture-free and pain-free on the right side, suggesting a possible benefit of Teriparatide use in patients at risk for impending AFF.

Our case demonstrates an expedited healing time (3.5 months) relative to previously reported average healing times for AFF (10.7 months), supporting the use of the combination of Teriparatide and a novel surgical technique.