Connector for attaching an alignment rod to a bone structure

Abstract

A connector for a spinal alignment system includes a base, a hook, a guide aperture, and a locking portion. The base includes a channel extending therethrough to receive a fixation rod. The hook extends from the base. The guide aperture is adapted to receive a bone fastener and the locking portion is adapted to engage the bone fastener. The guide aperture extends through one of the base and the hook and the locking portion is located in the other of the base and the hook. The locking portion is coaxial with the guide aperture such that the guide aperture guides a shaft of the bone fastener into alignment with the locking portion when the bone fastener is received by the guide aperture. The bone fastener cooperates with the base and hook to form a tension band construct that resists opposing forces acting on the construct. A rod locking fastener engages the channel and the fixation rod to secure the fixation rod in the channel. The rod locking fastener and the base include mating surfaces that cooperate with each other to resist the force exerted by the fixation rod onto the rod locking fastener when the fixation rod is secured in the channel.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The invention relates generally to a spinal alignment system for treating spinal deformities and / or injuries and, more particularly, to securing a spinal alignment system to a spinal column. [0003] 2. Description of the Related Art [0004] Deformities of the spine and injuries to the spine have long been treated by surgical intervention. In treating deformities and injuries to the spine, the goal is to return the spine, to the extent possible, back to a normal curvature and / or hold it in a desired position. Several surgical intervention techniques and devices have been proposed for the treatment of injuries to and deformities of the spine. [0005] Some of these surgical techniques use a hook and rod system to hold the spine in a desired position. In such systems, the rod can be placed along the outside of the curved spine, that is on the convex side, and can be attached to the vertebrae of the spine by hooks as illust...

AI Technical Summary

Benefits of technology

[0014] The invention solves the problems and / or overcomes the drawbacks and disadvantages of the prior art by minimizing the adverse effects of the tensile and compression forces acting on the various securements of the spinal alignment system. In particular, the invention accomplishes this by providing a connector for a spinal alignment system including a base, a hook, a guide aperture, and a locking portion. The base includes a channel extending therethrough to receive a fixation rod. The hook extends from the base. The guide aperture is adapted to receive a bone fastener and the locking portion is adapted to engage the bone fastener. The guide aperture extends through one of the base member and the hook member and the locking portion is located in the other of the base and the hook. The locking portion is coaxial with the guide aperture such that the guide aperture guides a shaft of the bone fastener into alignment with the locking portion when the bone fastener is received by the guide aperture.

Problems solved by technology

This pulling force at the ends of the rod can be of such magnitude that the hook and rod system can fail.

Regardless, the desired position of the spine can be lost.

Hook pull off and failure is not limited to the compression mode, it is also a problem in the distraction mode for this type of system.

In addition, the ratcheted rods in the distraction mode could break at the ratchet points, again causing system failure.

Moreover, because the bone of the vertebrae is mostly cancellous and is relatively weak, it is not a preferred bone type for thread fixation.

The weaker bone material is more likely to fail than the screw.

As a result, the screws that are subject to the pulling forces described above can experience pull out and failure.

But these larger features can disrupt too much of the vertebrae and cause the vertebrae to fracture, independent of screw pull out.

However, the screw is still subject to failure by pull out and the threads can still cause the vertebra to fracture.

But use of both a hook and a screw does not eliminate the problems associated with each.

The hook can still experience slippage and the screw can still experience pull out.

Although these devices can provide for a more reliable mounting of the rod onto the spinal column over other devices, these devices, as stated above, cannot eliminate hook slippage and bone screw pull out.

But nuts used on the far side of the screw in the spine are difficult to place and to hold until secure.

The screw can be sharp, tearing gloves, exposing skin or even cutting the surgeon.

Also, for the nut to relieve the screw threads from being the sole resistance force to pull out, the nut must be sufficiently tight against the bone, which is difficult to achieve by hand (without a holding device so that the nut does not spin while tightening is occurring).

The use of a nut with the screw can be a difficult, cumbersome and time consuming procedure at best.

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