Abaloparatide Added to Ongoing Denosumab vs Continued Denosumab Alone

Inclusion Criteria: * postmenopausal woman \>age 45 of any racial origin * Participants will have received at least 4 prior denosumab treatments and be within 7 months from their last denosumab injection * Participants are willing to participate for the duration of the study and have no physical or psychological illness that would prohibit them from participating. * Diagnosis of osteoporosis based on bone mineral density and/or fracture criteria. Osteoporosis will be defined by bone mineral density T-Score \< -2.5 at lumbar spine (at least 2 evaluable vertebrae between L1 and L4), total hip or femoral neck. Osteoporosis will also be defined clinically in women with osteoporotic fractures within the preceding 5 years, including clinical vertebral or nonvertebral fractures or vertebral fracture confirmed by radiograph or lateral DXA VFA image, along with a DXA BMD T-Score \< -1.5 at one or more skeletal sites. Exclusion Criteria: * Use of drugs other than denosumab (within the preceding 3 months) known to affect skeletal or calcium homeostasis. * Fewer than 2 evaluable lumbar vertebrae * A history of a symptomatic renal stone within the past 2 years or history of multiple symptomatic renal stones within the preceding 10 years * Skeletal Disorders other than osteoporosis, including hypercalcemia, hyperparathyroidism, or Paget's Disease * History of external or internal radiation therapy * Estimated GFR below 30 ml/min * Any contraindications to receipt of Abaloparatide or Den…