MON-351 Early Diagnosis and Management of Bilateral Transient Osteoporosis of the Hip in Pregnancy

Introduction: Transient osteoporosis of the hip (TOH) in pregnancy is a rare and under-reported condition. It is clinically characterized by a sudden onset of hip pain in young females without any history of systemic disorders or traumatic injuries (1). Bilateral involvement of the hips, such as in this case report, is less common than unilateral involvement. Clinical Case: A 33 year old G2P1 female presented to the hospital at 30 weeks gestation for described sharp, bilateral inguinal pain, greater on the left than right, worse with movement, and with progressive difficulty ambulating, of three weeks duration. She had no significant PMH, notably denying thyroid or calcium disorder, nephrolithiasis, osteoporosis, or steroid treatment. She denied tobacco, alcohol, or illicit substance usage. She only took prenatal vitamins. On physical examination, she had reduced active and passive range of motion of both hips, but normal muscle strength and no signs of infection or neurological deficits. Labs including CMP, LFTs, and TFTs were within normal range. 24 hour urine free cortisol was 54 mcg/24h (normal 3.5-45mcg/24h); repeat post-partum was 21 mcg/24h. 25OH-D was 18.3 ng/mL. MRI without contrast demonstrated “extensive abnormal marrow edema within the left femoral head and neck and small effusion, suspicious for transient osteoporosis of the hip. A subtle small focus of edema on the right was also noted. No discrete fracture line or subchondral collapse was noted.” The patient was managed conservatively with analgesics, thromboprophylaxis, and education regarding reduction of weight bearing activities, rest, and mobility aids with crutches. She was started on vitamin D. Her bilateral hip pain resolved by the 38th week. She had an uncomplicated cesarean delivery at 39 weeks to a healthy male neonate. At the one-month postpartum visit, she was ambulating independently without difficulty. She denied further pain, and passive and active ROM were intact without tenderness. Conclusion: TOH in pregnancy is usually a self-limiting disorder with no obvious etiology (2). It can present unexpectedly in the third trimester or early postpartum period in a healthy female with an otherwise uneventful pregnancy. In rare instances where fractures of the affected hip occur, surgical intervention may be necessary. MRI has become the diagnostic tool of choice for early diagnosis of TOH. Early diagnosis and optimal management are essential to prevent major complications such as traumatic fractures and deep vein thrombosis, as well as to prevent stress for the mother during the course of pregnancy. References: 1. Xyda, A. et al., (2008) Postpartum bilateral transient osteoporosis of the hip: MRI findings in three cases. La Radiologia Medica, 113(5),689–694. 2. Asadipooya, K., et al., (2017). Transient osteoporosis of the hip: Review of the literature. Osteoporosis International, 28(6),1805–1816.