summary Idiopathic Transient Osteoporosis of the Hip, is a self-limiting condition that leads to temporary loss of bone in the femoral head and neck, leading to hip pain and difficulty with ambulation. Diagnosis can be made with radiographs showing preserved joint space with diffuse osteopenia of the femoral head and neck. MRI studies will often show decreased signal with loss of fatty marrow on T1 studies. Treatment is observation with protected weight bearing as most cases resolve spontaneously within 6-8 months. Epidemiology Incidence rare Demographics men >women (3:1) 2 groups middle aged (40-55y) men women in 3rd trimester of pregnancy rare in Asians Anatomic location usually unilateral may recur Etiology Pathogenesis local hyperemia and impaired venous return with marrow edema and increased intramedullary pressure also referred to as bone marrow edema syndrome regional migratory osteoporosis migratory osteolysis Presentation Symptoms progressive, atraumatic hip and groin pain over several weeks may be unable to bear weight Physical exam local tenderness often have normal hip ROM Labs Elevated ESR Imaging Radiographs recommended views AP lateral findings (xray findings in femoral head and neck lag behind clinical signs by 4-8wks) subchondral cortical loss diffuse osteopenia of femoral head and neck joint effusion joint space is always preserved MRI imaging modality of choice shows marrow edema of femoral head and neck T1 decreased signal, loss of fatty marrow T2 high signal of marrow edema joint effusion Bone scan increased uptake in femoral head preceeds Xray changes Differential ITOH is a diagnosis of exclusion. Exclude femoral neck stress fracture infection malignancy AVN ITOH vs. Avascular Necrosis ITOH Avascular Necrosis Gender Male (3:1) Equal sex distribution Age Women 3rd trimester of pregnancy, middle aged men 20-40yo Laterality Unilateral Bilateral >50% Risk Factors 3rd trimester of pregnancy ETOH, Steroids Symptoms Acute pain, improves with PWB Insidious pain, progessively worse Exmination Preserved except at extremes of ROM Marked reduced ROM especially internal rotation Radiographs Diffuse osteopenia femoral head and neck at 4-6wk Localized sclerosis, crescent sign, collapse Bone scan Homogenous increased uptake femoral head and neck Localized uptake in femoral head and neck MRI Diffuse edema but NO focal defects or subchondral changes. Decreased T1, increased T2 signal. Focal defects/subchondral changes anterosuperior region of femoral head. Decreased T1 and T2 signal. Treatment Protected WB, symptomatic Early surgery recommended Prognosis Self limiting Progressive Treatment Nonoperative symptomatic with avoidance of weightbearing indications first line of treatment protected weightbearing to avoid stress fractures resolves spontaneously in 6-8mths Prognosis Generally resolves spontaneously in 6-8 months