A spinal screw extension instrument kit, comprising: a polyaxial screw having a receiving member with opposed slots formed therein and a compression member disposed within a distal portion of the receiving member; and a spinal screw extension instrument comprising: an outer component having an inner lumen extending therethrough and a distal end with opposed arms (70A, 70B) that engage the receiving member of the polyaxial screw such that opposed slots formed between the opposed arms (70A, 70B) are aligned with the opposed slots formed in the receiving member; and an inner component disposed within the inner lumen of the outer component and having a distal end with opposed arms (702A, 702B) and opposed slots (704A, 704B) formed between the opposed arms, the inner component being longitudinally translatable relative to the outer component such that the opposed slots (704A, 704B) of the inner component are aligned with the opposed slots (905; 114) of the outer component and the receiving member, the opposed arms (702A, 702B) of the inner component applying a distal force to the compression member of the polyaxial screw disposed within the distal portion of the receiving member to thereby convert the polyaxial screw to a monoaxial screw; wherein the outer component comprises an outer sleeve that engages a feature formed on an outer surface of the receiving member of the polyaxial screw and an inner sleeve disposed within the outer sleeve that abuts against an upper surface of the receiving member of the polyaxial screw. a polyaxial screw having a receiving member with opposed slots formed therein and a compression member disposed within a distal portion of the receiving member; and a spinal screw extension instrument comprising: an outer component having an inner lumen extending therethrough and a distal end with opposed arms (70A, 70B) that engage the receiving member of the polyaxial screw such that opposed slots formed between the opposed arms (70A, 70B) are aligned with the opposed slots formed in the receiving member; and an inner component disposed within the inner lumen of the outer component and having a distal end with opposed arms (702A, 702B) and opposed slots (704A, 704B) formed between the opposed arms, the inner component being longitudinally translatable relative to the outer component such that the opposed slots (704A, 704B) of the inner component are aligned with the opposed slots (905; 114) of the outer component and the receiving member, the opposed arms (702A, 702B) of the inner component applying a distal force to the compression member of the polyaxial screw disposed within the distal portion of the receiving member to thereby convert the polyaxial screw to a monoaxial screw; wherein the outer component comprises an outer sleeve that engages a feature formed on an outer surface of the receiving member of the polyaxial screw and an inner sleeve disposed within the outer sleeve that abuts against an upper surface of the receiving member of the polyaxial screw. an outer component having an inner lumen extending therethrough and a distal end with opposed arms (70A, 70B) that engage the receiving member of the polyaxial screw such that opposed slots formed between the opposed arms (70A, 70B) are aligned with the opposed slots formed in the receiving member; and an inner component disposed within the inner lumen of the outer component and having a distal end with opposed arms (702A, 702B) and opposed slots (704A, 704B) formed between the opposed arms, the inner component being longitudinally translatable relative to the outer component such that the opposed slots (704A, 704B) of the inner component are aligned with the opposed slots (905; 114) of the outer component and the receiving member, the opposed arms (702A, 702B) of the inner component applying a distal force to the compression member of the polyaxial screw disposed within the distal portion of the receiving member to thereby convert the polyaxial screw to a monoaxial screw; wherein the outer component comprises an outer sleeve that engages a feature formed on an outer surface of the receiving member of the polyaxial screw and an inner sleeve disposed within the outer sleeve that abuts against an upper surface of the receiving member of the polyaxial screw.