To investigate a new incidence and preventive effect of menatetrenone on vertebral fracture in patients with osteoporosis who were randomly assigned to either treatment arm receiving daily dose of calcium supplement as a monotherapy (calcium monotherapy group) or menatetrenone plus calcium supplement as a combination therapy (menatetrenone combo therapy group) for 36 months, followed by a 12-month follow-up observation to examine the preventive effect on the fracture risk.

Inclusion Criteria:

Inpatient or outpatient is not asked. If using any anti-osteoporotic agent other than calcium preparations (i.e., contraindicated for concomitant use stipulated in the protocol of this post-marketing study), such agent must be discontinued. Even after the discontinuation, calcium dosing is permitted with a condition that the subsequent use is started after a 8-week elapse from the discontinuation.

• Patients with primary osteoporosis (diagnosed according to "Diagnostic Criteria for Primary Osteoporosis issued by the Japanese Society for Bone and Mineral Research (1995)."
• Post-menopausal patients aged 50 years or older.
• Patients who agree to participate in a 4-year follow-up observation.
• Patients who provide written informed consent.

Exclusion Criteira:

• Patients on warfarin potassium (Warfarin®) therapy.

• Patients with hypercalcemia.

• Patietns with renal calculus.

• Patients with a known history of hypersensitivity to calcium or menatetrenone preparations.

• Patients with severe complication in the hepatic, renal, gastrointestinal, cardio- and cerebrovascular system.

• Patients who underwent bilateral ovariectomy.

• Patients with radiotherapy in the pelvis or para-aortic area.

• Patients with the following X-ray findings;

  1. Patients showing osteophytes connecting with adjacent vertebral osteophytes
  2. Patients showing hyperostosis of ligament around the vertebral body
  3. Patients showing inter-body fusion
  4. Patients who experienced surgical intervention(s) in the spine
  5. Patients with scoliosis which disturbs a diagnosing of vertebral fracture

• Patients who have been treated with anti-osteoporotic agents, other than calcium preparation, within 8 months prior to the study treatment (but not applied to the following; if discontinued, non-treated, or shifted to calcium monotherapy for 8 weeks or longer before starting the study treatment).

• Patients who experienced bisphosphonates in the past.

• Patients who are likely to show insufficient absorption of liposoluble agents such as biliary atresia, impaired bile secretion, etc.

• Other patients who are judged to be ineligible for study entry by the investigator or investigator.