There is a distinct difference between ballet injuries and sports injuries in general, and the sports medicine physician needs to study the technique of dance and the specific injuries that it may produce in order to treat dancers effectively. In Australia, which is typical of other countries where ballet is performed, ballet injuries include strained lumbar muscles, sprained ankle, Achilles tendinitis, clicking hip, jumper's knee, chondromalacia, stress fractures, patellar subluxation, and other knee and tendon problems.