A bone anchor assembly may include a bone anchor having a proximal head and a distal shaft configured to engage bone and a receiving member for receiving a spinal fixation element to be coupled to the bone anchor. The receiving member may have a first end having a first bore defining a first bore axis, a recess in communication with the first bore, and a second end having a second bore sized to receive at least a portion of the bone anchor. The second bore may define a second bore axis that intersects the first bore axis and may have a first opening through which the at least a portion of the bone anchor extends and a second opening opposite the first opening. The second opening may be sized to pass the head of the bone anchor during assembly of the bone anchor assembly.