Part 3

"A Guide To Anterior Ankle Impingement And Os Trigonum Syndromes
The extreme dorsiflexion required by the demiplié position in ballet can lead to impingement of the anterior lip of the tibia on the talar neck. Anterior ankle impingement results from osteophytes occurring on the anterior tibia and talar neck.
The dancer’s first recognition of the syndrome is lack of depth in the plié, which is often associated with poorly localized ankle pain. With time, the dancer may experience more localized symptoms to the anterior aspect of the ankle. These symptoms often include mild swelling. You can attain symptomatic improvement by encouraging the use of a 1/4-inch to 3/8-inch heel lift in street shoes, antiinflammatories and having the dancer discontinue forced plié.
Definitive treatment consists of excising the offending osteophytes, either arthroscopically or through an anterior arthrotomy. Keep in mind that you’ll often see secondary inflammatory changes involving the capsule, the fat pad and local synovium. An exostectomy merely extends the dancer’s career. Repeated impingement will invariably lead to recurrent exostoses, usually within three to four years. Repeat excision may therefore be required in some cases.
While it is rare in the general population, posterior impingement of the os trigonum is common in dancers. In extreme plantarflexion, an os trigonum, a large posterior tubercle or less commonly, a large dorsal process of the os calcis, is compressed intermittently for periods of up to six hours a day from the dancer standing in the demi-pointe position. The dancer with symptomatic posterior impingement presents with posterior ankle pain aggravated by relevé and relieved somewhat by plantar grade stance.
The differential diagnosis includes Achilles, peroneal and flexor hallucis tendinitis. However, for these conditions, the symptoms are rarely aggravated by plantarflexion. You can reproduce the pain of posterior impingement via forced plantarflexion. When it comes to treatment, you should emphasize a flexibility program, with attention to stretching, and an antiinflammatory medication. If symptoms become disabling, surgical excision of the bony mass is indicated."

This is a problem of your ankle as you spend more and more time standing on your tibia and locking your ankle. You would have to spend a lot of time doing this not a beginner's problem.