Lamina splendens – The protective top layer of articular cartilage

Neuropathic arthritis – The chronic, progressive destruction of a joint that is caused by the loss of sensation from an underly- ing neurologic dysfunction; also known as Charcot arthropathy

Osteonecrosis – The death of bone, often as a result of obstruction of its blood supply

Posttraumatic arthritis – A form of secondary osteoarthritis caused by a loss of joint congruence and normal joint biomechanics

Primary osteoarthritis – Osteoarthritis without an identified cause; characterized by pro- gressive loss of articular cartilage and reactive changes in the bone, leading to the destruction and painful malfunction of the joint

Secondary osteoarthritis – Osteoarthritis result- ing from known precipitants such as bone ischemia, trauma, and neuropathy