The metaphysis is a different material from the shaft: a lattice of trabeculae rather than a dense wall. Screws that work in cortical bone fail there, because purchase in trabecular bone comes from thread depth and span, not from thread count. The cancellous thread — deep and wide — is engineered around exactly that difference.
The classic application is screw-only fixation of metaphyseal fragments: condyles, plateaus, malleoli, where a partially threaded screw crosses the fracture line and compresses it as it seats, often with a washer spreading the load on the thin cortex. The same screws serve as the metaphyseal partners of plate constructs. Size and configuration remain selections of the operating surgeon.
