A tulip assembly configured to be coupled to a head of a bone fixation device. The steps of fixing include inserting the pedicle screw into a bone, the pedicle screw including a head portion, expanding a first inner member over the head portion of the pedicle screw after the pedicle screw is inserted into a bone, fixing an angle of the tulip assembly relative to the pedicle screw using the first inner member and a second inner member, the first and second inner members situated in an outer member of the tulip assembly and positionally locking a rod in the tulip assembly after the angle is fixed by rotating the second inner member and outer member relative to each other after the fixing step.