Length adjustable modular screw system

Inventors

Geist, Wyatt Drake • SOUZA, JR., John

Assignees

Geist Wyatt • Folsom Metal Products Inc • Kapstone Medical LLC

Abstract

A system including anchors, anchor components, and anchor assemblies and subassemblies that are adapted for attachment to a bony structure of a clinical subject. For example, two or more such anchors in the form of screws may be affixed to bones, for example, vertebral structures such as the pedicle, and each anchor is connected to a stabilizer such as a surgical rod that is inserted between the anchors. The anchors and assemblies are novel in many respects owing to their modular nature and height adjustability, which in contrast to conventional systems, allows the anchors to be provided to a surgeon in modular, sub assembled and fully assembled form to enable a broad array of choices in devising the optimal plane for surgical bone fixation.

Core Innovation

The invention provides a length adjustable modular anchor system for engagement with a bone, implemented as a length adjustable modular screw comprising a neck assembly and a shank. The neck assembly includes an expander component and a collet component with cooperating features that are compressible together to splay the collet, and the expander component is insertable within a through channel in the collet component along a common axis.

The neck assembly is adjustably engagable within the shank to achieve variable length of the length adjustable modular screw by sliding the engaged neck assembly within the shank socket along the common axis. The shank includes a threaded portion with an aperture in communication with a socket that extends within the shank to receive at least a portion of the collet, and the modular screw length is selected by compressing the components of the neck assembly together to splay a portion of the collet component within the shank socket.

Structural mechanisms described include a matable seat and head for coupling, collet through slots oriented parallel to the common axis, and a through channel originating within the seat and extending through the distal end of the collet. The invention also describes locking and stabilization structures associated with length adjustment and fixation, including a shaped recess and complementary protuberance to prevent pull-out, an anti-pull-out locking interface, and stabilization structures such as a floor and a cannula for off-axis stabilization.

The system is integrated with spinal rods plus retaining housings, locking elements, and optional compression washers, with length adjustment achieved by sliding along the common axis and fixing the vertical position by compressing the rod/retaining housing.

Claims Coverage

The provided material includes three independent claim families, each centered on a length adjustable modular anchor system/screw for bone engagement. Across the independent claims, the core inventive structure is the same: a neck assembly with an expander and collet that compress to splay the collet, and a threaded shank with an internal socket/aperture that receives the neck assembly to provide adjustable length by sliding along a common axis. Claim 16 additionally specifies spinal-rod securing hardware and compression washers.

Across the independent claims, the inventive concept is a modular anchor system where a neck assembly (expander + collet) is slidably engaged within a shank socket to vary length along a common axis, and the chosen length is fixed by compressing the neck assembly to splay the collet within the socket. Claim 16 further adds integration with spinal rods via a retaining housing, locking element, and compression washers.

Stated Advantages

Documented Applications