Combination Risedronate - Parathyroid Hormone Trial in Male Osteoporosis

Inclusion Criteria: 1. Males, ages 30-85 with osteoporosis. 2. Osteoporosis can be due to hypogonadism, past steroid use, or idiopathic. 3. Patients with hypogonadism can be included if their replacement dosage of testosterone has been stable for at least 18 months. 4. Bone mineral density must be 2 or more standard deviations below (T-score 2.0) the young adult peak for men at the lumbar spine, the hip or the radius. 5. Normal renal (glomerular filtration rate \>= 60 ml/min) and liver (less than or equal to twice the normal limits for ALT and AST) function. Exclusion Criteria: 1. Use of any specific osteoporosis drug in the previous 6 months. 2. Known or suspected metabolic bone diseases (such as renal osteodystrophy, osteomalacia) other than osteoporosis. 3. Preexisting hypercalcemia or an underlying hypercalcemic disorder, such as primary hyperparathyroidism. 4. Secondary hyperparathyroidism. 5. Paget's disease of bone or fibrous dysplasia. Teriparatide should not be given to patients with these conditions due to an increased risk of osteosarcoma. 6. Patients with any elevations of alkaline phosphatase that are secondary to bone disease, as such individuals may be at risk for osteosarcoma. 7. History or presence of any malignancy, except dermatological, but including melanoma. Known or suspected bone metastasis, or a history of skeletal malignancies. 8. Prior radiation therapy. Patients with prior radiation therapy should be excluded from treatment with teriparatide. 9. Any medical condition, which in the opinion of the investigator could preclude study participation, including but not limited to cardiovascular, gastric, renal and hepatic disorders, or abnormal PSA test. In particular, patients with active or recent (within the last 2 years) urolithiasis will be excluded. 10. History of previous major bowel surgery including bowel resection. 11. Oral use of systematic glucocorticoids for two or more weeks in the previous six months. 12. Parenteral use of systemic glucocorticoids on more than two occasions in the previous six months. 13. Use of anticonvulsant drugs. 14. History of uncontrolled diabetes mellitus (Patient with Type 2 diabetes who have HbA1C\< 8 are permitted to be enrolled). 15. Hypercalciuria (\> 4 mg/kg/day). 16. Impaired liver function (\>twice the upper normal limits for ALT and AST). 17. Hyperadrenalism as assessed by physical examination. 18. Any other clinically significant laboratory abnormalities, which are deemed relevant to the design of the protocol. 19. Patients with known hypersensitivity to any of the test materials (teriparatide or risedronate) or related components (metacresol, mannitol, glacial acetic acid, sodium acetate). 20. Use of any investigational or unlicensed drug in the previous 30 days. 21. Patients who may be unreliable for the study, including those engaging in excessive alcohol consumption or drug abuse or patients who are unable to return for scheduled follow-up visits. 22. Patients who are unable or unwilling to comply fully with the protocol. 23. Inability to stand or sit upright for at least 30 minutes 24. Those with history of esophagitis, Barrett's esophagus, esophageal/peptic ulcers or esophageal motility disorders 25. Hypocalcaemia 26. Renal dysfunction (GFR \<60) 27. Patients planning invasive dental work such as implants, extractions or procedures involving the jaw bone or patients with poor oral hygiene 28. Use of digitalis. 29. Patients with HIV/AIDS.