Review Question - QID 219482

This 86-year-old female presents to the emergency department with an atypical femur fracture (AFF) secondary to her chronic bisphosphonate use. Teriparatide has been shown to improve union rates in patients with AFFs (Answer 4).

Atypical femur fractures are uncommon, accounting for 1-2% of all femur fractures. These injuries are associated with bisphosphonate and denosumab and are believed to result from the extremely low rate of bone turnover associated with these medications. Over time, microtrauma accumulates, leading to compromised bone, manifesting clinically as thigh pain and eventually AFFs. AFFs are notorious for having poorer union rates than conventional femur fractures, again being attributed to the bone's poor healing capacity secondary to reduced bony turnover. Following fixation, the offending agent is discontinued, and the prospect of initiating teriparatide is often entertained. Teriparatide, which is a recombinant parathyroid hormone and is one of the most common anabolic osteoporosis medications available, has shown promise in improving fusion rates in the spine and distal radius fractures, as well as AFFs.

Salamah et al. performed a systematic review and meta-analysis of eight studies (238 patients) analyzing the effect of teriparatide on AFFs. The authors noted a significant reduction in time-to-union as well as a reduced incidence of delayed and non-unions. The authors conclude teriparatide appears to improve healing rates in AFFs, but note more studies of higher power are needed to validate their findings given the rarity of AFFs.

Black et al. examined the risk of AFFs in women greater than 50 years of age and on bisphosphonates (n=196,129). The authors noted longer bisphosphonate use portended significantly higher risk, with those taking bisphosphonates 3-5 years having a hazard ratio of 8.9 and users greater than 8 years having a ratio of 43.5. The authors conclude the findings of this study may assist clinicians when deciding to have patients undergo drug holidays.

Van de Laarschot et al. performed a systematic review of 67 articles examining the incidence and healing capability of AFFs in patients who had used or were using osteoporotic medications, namely teriparatide, denosumab, raloxifene, romosozumab, or abaloparatide, to provide medical treatment recommendations following AFFs. The authors recommend discontinuation of bisphosphonates or denosumab upon the finding of unilateral impending AFFs or AFFs. Teriparatide may be initiated following an AFF, as studies have concluded the medication may allow shortened duration for time-to-healing.

Figures A and B represent plain films of a mid-shaft AFF. Illustrations A & B demonstrate post-operative fixation of the fracture.

Incorrect Answers:
Answers 1, 2, 3, and 5: these medications have not shown utility in improving union rates in AFFs