A knee wound is an injury to the knee joint, which is a hinge joint that connects the thigh bone to the lower leg bone. The most common cause of a knee wound is trauma, such as a fall or a blow to the knee. The term 'SCRAPE' is used to describe a shallow wound caused by friction, such as when the skin is scraped against a rough surface. Scrapes can be painful and may cause bleeding, swelling, and bruising.