Workers often sustain injuries that affect multiple parts of their body. However, injuries to the upper extremities (shoulder, arm, wrist, hand), trunk (including the back), and lower extremities (knee, ankle, foot, toe) far outnumber injuries to the head, neck, other body systems, and multiple parts of the body. About one-third of workplace injuries involving days away from work involve the upper extremities, with hand injuries the most common. Trunk and lower extremity injuries each account for about a fourth of all injuries. Knee injuries are the most common lower extremity injury. Back injuries account for three-fourths of trunk injuries. (Reference Table 6B.3.1 PDF CSV)