Spinal Alignment Apparatus for Vertebral Derotation
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Solution Overview
Problem
Current methods for treating spinal deformities, such as scoliosis, often fail to effectively address both translational and rotational aspects of the deformity across all three spatial planes, leading to incomplete correction and complications in rod placement due to vertebral rotation.
Innovation Solution
An elongate alignment apparatus with a slot system and locking mechanism that allows for the secure attachment of bone anchors and a reduction rod, enabling simultaneous translation and derotation of vertebrae along the coronal, transverse, and sagittal planes, thereby correcting spinal deformities in a three-dimensional manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pedicle screws are anchored to a scoliotic spine, then the possibility of derotation is raised, but the screws follow the curvature of the spine and tend to be inclined in the transverse plane depending on vertebral rotation, thereby complicating placement of the spinal rods
Solution Approach 1:
The alignment element is divided into distinct functional segments: a bone anchor receptacle for securing the pedicle screw, a slot system for rod engagement, and a locking mechanism for fixation. This segmentation allows each component to perform its specific function independently, enabling derotation capability while simplifying rod placement procedures.
Solution Approach 2:
The alignment element serves as an intermediary device between the pedicle screw and the spinal rod. It provides a standardized interface that decouples the inclined screw placement (which follows spinal curvature) from the rod placement (which requires precise alignment), thereby enabling derotation without complicating rod insertion.
2Manufacturing precision
If traditional anchoring devices are used to reduce translational aspects of deformity, then translational correction is achieved, but there is little or no effect on the rotational aspects
Solution Approach 1:
The alignment element is designed as a multi-functional device that simultaneously addresses both translational and rotational aspects of spinal deformity. It combines the translational correction function of traditional anchoring devices with derotation capability through its slot system and locking mechanism, making it universally applicable to correct all three spatial planes of scoliosis.
3Manufacturing precision
If pedicle screws are forced into engagement with the rod or the rod is bent/rotated after engagement, then alignment is achieved, but the process is time-consuming and complex
Solution Approach 1:
The alignment element is pre-configured with the slot and locking mechanism in specific geometric relationships before surgery. The slot is pre-oriented to receive the rod in the desired alignment, and the locking mechanism is pre-positioned to secure the rod at the correct angle. This preliminary preparation eliminates the need for time-consuming intraoperative bending or rotation of the rod, significantly reducing surgical time while maintaining precise alignment.
Data Source
AI summary
A bone anchor assembly is provided, which may be used in cervical, thoracic, lumbar or sacral areas of the spine or other orthopedic locations. The anchor assembly includes a bone anchor, a receiver mounted to the bone anchor, a saddle within the receiver, a spacer within the receiver, and an engaging member. The receiver extends along a central longitudinal axis proximally away from the bone anchor. A rod or other elongated connecting element is received in a passage of the receiver in contact with the saddle, and the engaging member engages the connecting element against the saddle, which engages the saddle against the spacer, which in turn engages the proximal head of the bone anchor in the receiver. The orientation of the saddle in the receiver is adjustable to correspond to the orientation of the connecting element relative to the central longitudinal axis of the receiver.