An instrument for assembling a polyaxial bone anchor is provided, the polyaxial bone anchor including a bone anchoring element (2) and a receiving part (4) that is configured to pivotably receive the bone anchoring element wherein the instrument (1, 1’) includes a first member (30, 30’) that is configured to engage the receiving part (4), a second member (50, 50’) that is configured to contact the anchoring element (2) when it is received in the receiving part, and a position indicator (50b, 45b) that is configured to indicate the position of the anchoring element relative to the receiving part based on the position of the second member relative to the first member.本案提供一種多軸式骨骼固定器之組裝用具,多軸式骨骼固定器包含骨骼固定元件(2)和容納件(4),後者構成樞動容納骨骼固定元件,其中用具(1,1’)包含第一構件(30,30’),構成結合容納件(4);第二構件(50,50’),構成當容納於容納件內時,接觸到固定元件(2);和位置指示器(50b,45b),構件根據第二構件相對於第一構件之位置,指示固定元件相對於容納件之位置。1‧‧‧組裝用具2‧‧‧骨骼固定元件3‧‧‧骨骼固定元件頭部4‧‧‧容納件30‧‧‧第一構件100‧‧‧脊椎骨
