Intra-articular dislocation of the patella: a rare variant to an uncommon injury.

Horizontal intra-articular dislocation of the patella is a very rare traumatic entity. We present an unusual case of horizontal intra-articular dislocation in which the patellar articular surface was facing upwards besides having an avulsion of the quadriceps tendon from the superior pole. There was associated posterolateral knee subluxation, which has not been described with intra-articular dislocation of the patella. A 20-year-old man presented with open patellar dislocation and locked knee after a roadside accident. The patient was managed successfully by open reduction and repair of the quadriceps tendon. There was buttonholing of the medial femoral condyle through the medial retinaculum leading to irreducible dislocation. A special reduction manoeuvre was employed to bring the knee to its normal alignment. Knowledge of this injury pattern is of utmost importance for proper recognition and appropriate allocation of the surgical technique. © BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ.