Which condition is considered a disorder of the musculo-skeletal system?

Osteoporosis is correctly identified as a disorder of the musculoskeletal system because it specifically affects the bones, making them weak and more susceptible to fractures. This condition results from a decrease in bone density and changes in bone structure, which directly impacts how the musculoskeletal system functions.

Understanding osteoporosis provides insight into how important bone health is for overall mobility and strength, enabling individuals to perform everyday activities without undue risk of injury. The other conditions listed do not primarily affect the musculoskeletal system; diabetes mellitus is an endocrine disorder, seizures affect the neurological system, and constipation relates to digestive health. Thus, osteoporosis stands out as the condition that primarily involves the musculoskeletal system.