The medial column is where distal humerus constructs are most often lost. The bone of the medial epicondyle is thin, the trochlea sits just beyond it, and in elderly or comminuted fractures the metaphysis offers little for a conventional screw to bite. A construct that relies on compression alone in this corridor is asking a lot of poor bone.
A locking medial plate changes that equation. Each distal screw locks into the plate at a fixed angle, so the whole distal cluster works as one unit supporting the trochlea side of the joint block, even when the bone around the threads is soft. Longer versions carry the fixation up the medial ridge when the fracture line escapes the metaphysis. Indication, length and screw configuration remain with the operating surgeon.