Posterior ankle decompression - operative indications

Initially consider activity restriction and ultrasound guided injections. If unsuccessful then posterior ankle decompression is indicated. Clinically the diagnosis is usually clear. However an Os trigonum is not always present (though usually is) in cases of posterior impingement. An MRI will confirm the presence of an Os Trigonum and also that it is inflammed. It should be borne in mind that not all cases of posterior ankle impingement result from extra-articular causes. It is possible that intra-articular problems such as posterior synovitis, plica or chondral injury may result in similar symptoms. These will however return normal imaging of the posterior soft tissues.