Orthopaedics What is the World Health Organization (WHO) definition of osteoporosis? A Bone mineral density less than 1 standard deviation below the mean of a young, healthy adult. B Bone mineral density at least 2.5 standard deviations below the mean of a young, healthy adult. C T score less than -2.5. D (B) and (C). 💡 Explanation What is the World Health Organization (WHO) definition of osteoporosis? ✓ Correct Answer: D. (B) and (C).