Abstract: An external fixation device for reducing fractures and realigning bones comprises sliding universal articulated couplings for enabling easy adjustment and subsequent locking of connections between Steinmann pins and tubular tie-rods. The couplings each include a split, spherical adapter sleeve which is embraced by the matching inner surface of an open ring portion of a coupling locking clamp having clamp lugs tightenable against a block by means of a nut-and-bolt assembly. Further nut-and-bolt assemblies are disposed in elongated slots in the blocks and cooperate with associated clamping members to clamp the Steinmann pins to the blocks after adjustment in two orthogonal directions and optional resilient bending of the pins.