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Anterior and posterior ankle impingement.

Anterior ankle impingement is characterized by anterior ankle pain on activity. Recurrent (hyper) dorsiflexion is often the cause. Typically, there is pain on palpation at the anteromedial or anterolateral joint line. Some swelling or limitation in dorsiflexion are present. Plain radiographs can disclose the cause of the impingement. In the case of spurs or osteophytes, the diagnosis is anterior bony impingement. In the absence of spurs or osteophytes, the diagnosis is anterior soft tissue impingement. In patients with anteromedial impingement, plain radiographs ae often falsely negative. An oblique view (anteromedial impingement view = AMI view) is recommended in these patients. Arthroscopic management with removal of the offending tissue provides good to excellent long-term (5-8 years) results in 83% of patients with grade 0 and grade I lesions. Long-term results are good/excellent in 50% of patients with grade II lesions (osteophytes secondary to arthritis with joint space narrowing). In posterior ankle impingement, patients experience hindfoot pain when the ankle is forcedly plantarflexed. Trauma or overuse can be the cause. The trauma mechanism is hyperplantarflexion or a combined inversion plantarflexion injury. Overuse injuries typically occur in ballet dancers and downhill runners, who report pain on palpation at the posterolateral aspect of the talus. On plain radiographs, an os trigonum or hypertrophic posterior or talar process can be detected. Surgical management involves removal of the os trigonum, scar tissue, or hypertrophic posterior talar process. In the case of combined posterior bony impingement and flexor hallucis longus tendinopathy, a release of the flexor hallucis longus is performed simultaneously. Endoscopic management is associated with a low morbidity, a short recovery time, and provides good/excellent results at 2-5 years follow-up in 80% of patients.