Varus collapse is the way proximal humerus fixations most often fail: the head fragment tips inward, screws migrate, and the construct loses the reduction millimetre by millimetre. The biomechanical answer is support at the inferomedial corner of the head — the calcar region — where a well-placed screw turns a tipping fragment into a supported one.
The locking plate builds that support into the implant. Its threaded head screws lock to the plate at fixed angles, so the head cluster holds its configuration in osteopenic bone, and the inferomedial screw path gives the surgeon a direct route to the calcar. Longer plates carry the construct into the shaft when the fracture line escapes the metaphysis. Reduction quality, screw placement and plate length remain with the operating surgeon.
