A retrospective bicenter comparative study of surgical outcomes of atypical femoral fracture: Potential effect of teriparatide on fracture healing and callus formation

Abstract

Background: The main purpose of the present study was to assess the radiologic effect of teriparatide on fracture healing, including union rate, union time, and callus formation, by quantitative measurements using serial follow-up X-ray imaging examinations in patients with complete atypical femoral fractures (AFFs) treated using closed intramedullary nailing.

Methods: From January 2010 to October 2017, 58 consecutive patients with complete AFF who were treated with intramedullary nailing at two institutions were enrolled. Patients were classified into two groups: those who received teriparatide therapy (group A) and those who did not (group B). Teriparatide (Forsteo®; Eli Lily Co., Indianapolis, IN, USA) at a once-daily 20 μg dose was prescribed as continuous treatment of osteoporosis or with the expectation of better bone healing. Surgical outcomes, including union rate, union time, modified radiologic union score (mRUS), and callus formation at 3, 6, and 12 months postoperatively, were assessed to evaluate the effect of teriparatide on fracture healing. Quantitative measurement of callus formation was performed using the region of interest (ROI) tool in the picture archiving communication system (PACS).

Results: Non-union was not observed in group A, whereas two patients had non-union in group B. Union time was 18.3 ± 4.8 (range, 12-28) weeks in group A and 23.6 ± 9.5 (range, 12-64) weeks in group B and was significantly shorter in group A than group B (p = 0.010). The average mRUSs during periods A (3-4 months postoperatively), B (6-8 months postoperatively), and C (12-14 months postoperatively) were 10.0, 13.9, and 15.9 in group A, and 8.7, 12.0, and 14.9 in group B, respectively. The average mRUSs during periods A and B were significantly different (p = 0.027 and 0.011, respectively). The medial, posterior, and total callus areas during periods A and B were also significantly greater in group A than in group B. No difference was observed in the union rate between the two groups (p = 0.492).

Conclusion: Teriparatide may improve callus formation and shorten union time in patients with complete diaphyseal AFF who underwent closed intramedullary nailing.

Level of evidence: Level III retrospective comparative study.

Keywords: Atypical femoral fracture; Callus formation; Fracture healing; Teriparatide.