Certain injuries may cause pieces of bone and cartilage to break off and float inside the knee. This can cause swelling, locking of the knee, and pain. Arthroscopy can be used to remove these pieces. There are no known medical treatments that are known to cause these to dissolve. Many times these occur in an arthritic knee after spurs have broken off. An island of bone and cartilage in an otherwise normal knee is referred to an OCD, or osteochondritis dessicans, and may require drilling or placement of a screw to fix it. Occasionally, cartilage restoration procedures may be needed to fill in the defect.

Figure One: A loose body sits just in front of the ACL. This person had episodes of catching and locking before surgery