Dr. Christian Puttlitz and Ben Gadomski at Colorado State University have developed a dynamic spine stabilization device to treat damaged and deteriorated intervertebral discs and allow for limited motion with restoration of the natural center of rotation. The current standard of treatment for high grade spinal disorders such as spinal stenosis and spondylolisthesis is a posterolateral fusion, which fuses two vertebrae together and restricts range of motion. While usually effective at treating spinal disorders, patients are then susceptible to Adjacent Segment Disease (ASD), wherein motion segments adjacent to the fused vertebrae degenerate more quickly due to increased loading and motion. In response, dynamic spine stabilization devices are sometimes used to secure the vertebrae while maintaining some range of motion, but these devices often alter the vertebral center of rotation, further causing wear and unnatural loading that can also lead to ASD and hardware failure.
Simply stated, the first device is comprised of two pedicle screws encased in head sockets with a rigid connecting rod that spans the pedicle screws. The screw head is allowed to move slightly within a slot in the head socket. When a pair of these assemblies is bilaterally installed, spinal rotation is consistent with its natural rotational axis while still providing needed support, restricting motion, and minimizing adjacent vertebral damage (Figure 1). The inventors have developed multiple configurations of the screws, sockets, and connecting rods and have allowed for modification, reconfiguration, and adaptation as is necessary throughout the further development of the device.
The same concept of center of rotation restoration has also been implemented as an interspinous spacer. The interspinous spacer consists of a sliding head piece that connects to the superior spinous process of the spinal segment and a base piece which encases the head piece and attaches to the inferior spinous process of the spinal segment. Each component is created with a specific radius of curvature such that the head piece is allowed to slide within the base and allow limited rotation around a projected center of rotation.
Innovating over current technology, Puttlitz and Gadomski’s device is a superior alternative to both posterolateral fusions and current dynamic spine stabilization devices by allowing support and restricted motion to alleviate spinal conditions while still allowing limited motion along the natural center of rotation.