Destructive osteochondral fracture of the lateral femoral condyle following traumatic patella dislocation

Abstract

This is a mid-20s male who presented following a stumble down several steps. The patient at the time of injury was three months postop femoral MPFL avulsion and subsequent anchor refixation, subsequent to a first episode of traumatic lateral patella dislocation. The initial postoperative course was unremarkable, the patient describing no subjective patella instability or knee problems. The current injury was not sustained because of a recurrence of dislocation rather it appears that in the process of falling, the patella has dislocated laterally with a medial bony avulsion of the medial capsuloligamentous attachment. Additionally evident is a degree of bony injury to the lateral femoral condyle. The extent of this injury was initially underappreciated on imaging, but became evident at time of surgery, which we will see. This patient does have a dysplastic trochlea with medial trochlea hyperplasia, a small thin patella with low lateral patellar facet angle. The Wiberg angle is almost unrecognizable with a soft transition between medial and lateral facets. On the lateral plane films, we can appreciate a marked trochlea bump and although not evident on the presented films, a positive crossing sign .