Any injury occurring at work, including aggravations of a pre-existing condition, a gradual onset of symptoms or an illness. Some examples of injuries that occur at work may include sprains, strains, lacerations, contusions, herniations, tears, fractures, from falling, lifting, running machines, bending or any activity while at work. An employee may also have a long standing condition that was made worse due to their work activities. Some common conditions that may be aggravated by work include: degenerative disc disease, herniated disc, hearing loss, prior shoulder injuries and prior knee injuries. A gradual onset of symptoms is called a Gillette Injury. This is commonly seen in repetitive jobs where the employee lifts frequently or uses the same repetitive motions in assembly or packing, resulting in the onset of pain over time. Illnesses may be as result of chemical exposure, heart failure or the consequence of an injury sustained at work.