UNIPLANAR SCREW ASSEMBLY

A pivotal screw assembly (100) for securing a fixation rod (190) comprising:a screw (120) having a longitudinal axis (102), a proximal end with a head portion (121), and a distal end with a threaded shaft portion;an insert (180) operably coupled with the head portion, the insert having a pair of extensions (184) projecting radially away from an exterior surface (182) of the insert; anda body member (140) operably coupled with the insert, the body member comprising side walls (134) having two slots (132) at an upper end that define a transverse channel sized to receive the fixation rod, the sidewalls having upper interior surfaces with threaded portions (138) formed therein and an interior distal surface including a pair of pockets (144) configured to receive a respective extension of the pair of extensions,wherein the body member is independently rotatable relative to the screw about the longitudinal axis when the head portion of the screw and the insert are disposed within the body member, with the pair of extensions operably engaging the pair of pockets so as to allow the body member to pivot relative to the screw only about a transverse axis (104) defined by a line extending between the pair of extensions, prior to the assembly being locked by the locking cap.