SAT262 Bilateral Stress Fractures Of The Femur In A Patient With HIV On Long-term Tenofovir Disoproxil Fumarate And Short-term Alendronate

Disclosure: R.J. Mahatme: None. A.D. Lindsay: None. F.S. Mirza: None. Background: Tenofovir disoproxil fumarate (TDF) is a reverse transcriptase inhibitor used for HIV treatment, which has been documented to reduce bone mineral density through enhanced osteoclastic activity, reduced osteoblastic activity, disrupted calcium absorption and renal phosphate wasting. Prolonged use of TDF increases the risk of osteoporosis and fractures. Bisphosphonates (BP) are typically used to prevent osteoporotic fractures by inhibiting bone resorption. However, BP use for more than five years, and concomitant suppression of bone remodeling may be associated with an increased risk of subtrochanteric fractures. We report a case of unusual bilateral subtrochanteric stress fractures of the femur in a patient on long term TDF for HIV, who had taken alendronate for a very short duration. Clinical Case: A 56-year-old woman presented to orthopedics in 2017 with complaint of bilateral leg/hip pain associated with weight bearing. Past medical history was significant for HIV diagnosed in 1995, osteopenia diagnosed in 2015 and fibromyalgia. The patient had been taking TDF as part of HIV therapy since 1995 and had been started on alendronate 15 months prior for osteopenia. X-ray of the hips revealed diffuse osteopenia with areas of possible stress reaction/stress fracture at the proximal third of the right femur and in the subtrochanteric left femur. Nuclear medicine bone scan showed faint foci of increased uptake in the lateral subtrochanteric regions of both proximal femora and midshaft of the right femur suggesting insufficiency fractures. The report noted that these areas were present and unchanged compared to a prior bone scan from 2011. In view of significant discomfort and risk of progression to full fracture, she underwent prophylactic intramedullary nailing of the right femur and was referred to endocrine for bone health evaluation. Endocrine evaluation showed vitamin D insufficiency and suboptimal calcium intake which were both corrected. A call to the pharmacy revealed that she had only filled 3 prescriptions of alendronate even though she was initially prescribed alendronate a year and a half prior to her presentation. Alendronate and TDF were discontinued and tenofovir alafenamide (TAF) was added to her HIV regimen due to its less deleterious effects on the skeletal system. Patient did not report significant improvement in her leg pain after the intramedullary nailing and decided to maintain a conservative approach without intervention for the left femur stress fractures. Conclusion: This is an unusual presentation of bilateral stress fractures of the femur likely related to long term TDF therapy in a relatively young postmenopausal female who had taken alendronate for less than a year of cumulative dose. This case highlights the need to use medications that have less harmful effects on the bone in adults with HIV who are also at an increased risk for low bone density and fractures. Presentation: Saturday, June 17, 2023