Atypical femoral fracture (AFF) is an uncommon complication that is related to long term bisphonphonate use. (1,2) We have treated a 61 year old Vietnamese female who sustained bilateral AFF with prolonged bisphosphonate use. She experienced premature menopause at the age of 38 and had history of previous fracture in her left ankle more than 20 years ago. She was on weekly alendronate for 12 years for her osteoporosis. She had a fall from standing height, and sustained a left AFF. X ray examination further showed contralateral stress fracture (Figure 1) and she received bilateral intramedullary nails. While in rehabilitation, she was given 60mg of denosumab one month post surgery. Her post-operative BMD confirmed osteoporosis with T score of -3.07 in proximal radius/ulna and -2.37 in lumbar spine. She was hesitant to receive teriparatide due to the fear of self-injection. Bone turnover markers 6 months post surgery showed normal CTX 200 ng/L (<1000 post menopause) and P1NP 22 ug/L (15-85 post menopause). Her case illustrates the risk of AFF with prolonged usage of bisphosphonate. It also highlights the challenges of osteoporosis management after AFF, in which both bisphosphonate and denosumab are inappropriate. (2,3) While current recommendation suggests consideration of anabolic agent teriparatide, (4) therapeutic options after teriparatide are unclear.

Figure 1a. Right transverse subtrochanteric stress fracture originating from lateral cortex with periosteal beaking and 1b. Left transverse subtrochanteric fracture with no comminution.