As baby boomers age, so do their bones, muscles, and joints creating lots of aches and pains. Almost three-quarters of doctor visits for lower back pain are made by young and middle-aged adults. And boomers are now undergoing a record-number of knee and hip replacements. This show examines the biology and pathology of middle-age on the musculoskeletal system highlighting how and why so many baby boomers are taking normal wear and tear to new limits. Producer Kay Colby has a preview.