Length adjustable modular screw system

Inventors

Geist, Wyatt Drake • SOUZA, SR., John

Assignees

Geist Wyatt • Folsom Metal Products Inc • Kapstone Medical LLC

Abstract

A length adjustable modular screw includes a neck assembly and a shank. The neck assembly has proximal and distal ends and includes an expander component and a collet component that are slidably engagable by insertion of the expander component in a through channel of the collet component along a common axis. The length adjustable modular screw also includes a shank suitable for insertion and retention within a bone, the shank including a threaded portion between proximal and distal ends and a socket adapted to coaxially receive at least a portion of the distal end of the neck assembly. The length adjustable modular screw has a length that is selected by splaying at least a portion of the distal end of the engaged expander and collet components of the neck assembly within the socket of the shank.

Core Innovation

The patent describes a length adjustable modular screw for spinal fixation, including a bone-implantable shank and a neck assembly. The neck assembly includes an expander component and a collet component with proximal and distal ends, and the expander component is slidably engagable with the collet component by insertion of the expander into a through channel of the collet component along a common axis.

The screw length is selected by splaying at least a portion of the distal end of the engaged expander and collet components within the socket of the shank. The neck assembly moves between open/mated and compressed configurations, while retaining the engagement along the common axis, so that the adjustable length is achieved by splaying within the socket.

The disclosure also describes formation of a generally spherical head by mating a head of the expander component with a seat of the collet component at the proximal ends. Additional described structural aspects include optional locking features and interface features, a retaining housing that accepts a rod and a fixation/locking element, an optional shank socket cannula for off-axis stabilization, and optional shaped recess/protuberance features for limiting pullout and/or rotation.

Claims Coverage

The partial content includes two independent claims. Both independent claims share the core length-adjustment concept using an expander and a collet slidably engaged along a common axis through a through channel, with length selection by splaying within a shank socket. The second independent claim adds the proximal mating interface that forms a generally spherical head.

Across the independent claims, the inventive concept is a neck assembly with an expander and a collet slidably engaged along a common axis through a through channel, where screw length is selected by splaying the distal end of the engaged expander and collet within a shank socket. The second independent claim further requires proximal head-seat mating to form a generally spherical head on the neck assembly.

Stated Advantages

Documented Applications