The clinical presentation is usually a limp with or without pain. Quantitative classifications were made by Catterall, Salter and Thompson, Herring lateral pillar, Mose, Stulberg end result classifications which of prognostic importance and therapeutic value. -Diagnosis is based on the clinical picture, radiography and other radiological investigations. Very high quality radiographs are needed to detect the subchondral fracture which enables us to discriminate between the cases at an earlier stage. Bone scan is a reliable method for early diagnosis and classification of the disease.