Systems, devices, and methods for percutaneously implanting a spinal screw provide reduced trauma to soft tissues, less blood loss and postoperative pain, less scarring, and faster mobilization compared to open spinal procedures. The devices and methods provide techniques for percutaneous insertion of pedicle screws or other screws without the use of a guide wire. Screw extenders are paired and include extending branches with elongated portions for extending from a proximal end outside a patient to a distal end. The screw extenders include interlocking tabs and other locking mechanisms at the distal ends that connect at the undersurface of a screw head and include a graduated bilateral locking mechanism to ensure a positive connection between the paired extender branches. The screw extenders are used through a working channel firmly held in place by a table-mounted flexible arm. The screw extenders can be used on available pedicle screw systems to convert their insertion to a percutaneous technique.
