The bones of the foot, wrist and hand leave no room for oversized hardware. Their periarticular plates are scaled accordingly, and the screws that lock those plates must hold a fixed angle at a diameter the bone can accept. Small-calibre locking is a discipline of its own: less material, less tolerance for error, same mechanical demands.
The universal locking family answers with a screw whose head engages the plate squarely and whose shaft is sized for small cortical and metaphyseal corridors. Locked at a fixed angle, even slim screws share load across the construct — the principle that makes locking fixation worthwhile in the first place, delivered at small scale. Length and configuration remain selections of the operating surgeon.