Instrument for assembling a polyaxial bone anchor

摘要

An instrument for assembling a polyaxial bone anchor is provided, the polyaxial bone anchor including a bone anchoring element and a receiving part that is configured to pivotably receive the bone anchoring element wherein the instrument includes a first member that is configured to engage the receiving part, a second member that is configured to contact the anchoring element when it is received in the receiving part, and a position indicator 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.

主权项

1. An instrument for assembling a polyaxial bone anchor, the polyaxial bone anchor comprising a bone anchoring element having a head and a shank and a receiving part configured to pivotably receive the head of the bone anchoring element, the instrument comprising:
a first member having a front end and a rearward end, the front end having a threaded engagement portion configured to releasably attach to the polyaxial bone anchor; a second member having a front portion and a rearward end, the front portion comprising a front end having a tip, wherein the second member is insertable into the first member; a position indicator located at a position away from the front portion of the second member and configured to indicate a distance between the front portion of the second member and the front end of the first member when the second member is inserted into the first member; and a spring configured to bias the front portion of the second member to protrude from the front end of the first member when the second member is inserted into the first member; and wherein the front portion of the second member is movable with respect to the front end of the first member when the second member is inserted into the first member.