Musculoskeletal disorders Musculoskeletal disorders include those conditions and diseases for example arthritis, osteoporosis and low back pain, which involve the major muscle groups and the skeletal system. Musculoskeletal disorders are the main sources of chronic pains and form the most common complaints especially among the elderly. Mackinnon (2003, P.223) notes that osteoarthritis is the most common form of arthritis and among the leading cause of Disability-adjusted life years (DALYs).