Spinal Fixation with One-Way Gear Clips for Vertebral Height
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Solution Overview
Problem
Current spinal fracture reduction systems face challenges in achieving ideal load distribution and maintaining vertebral body height due to the limitations of posterior pedicle screw nail fixation, leading to issues like vertebral body collapse, kyphosis, and pedicle screw nail fractures.
Innovation Solution
An internal fixation system with injured vertebra nails connected by reduction connecting clips and a connecting rod, featuring a one-way gear structure and non-circular limiting grooves, allows for automatic reduction and intravertebral bone grafting, reducing the need for repeated adjustments and minimizing interference with zygapophyseal joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If posterior pedicle screw nail fixation is used to restore vertebral body height, then vertebral body height is restored, but ideal load distribution in the anterior and middle parts of the injured vertebra cannot be achieved
Solution Approach 1:
The fixation system is divided into upper and lower connecting rods that can be independently adjusted, allowing separate control of vertebral body height restoration and load distribution. The reduction connecting clips with one-way gear structures enable independent adjustment of each rod's angle and position, providing segmented control over the reduction process.
Solution Approach 2:
The connecting rods are designed with adjustable angles and positions through the one-way gear reduction connecting clips, transforming the static fixation into a dynamic system that can be adjusted during surgery to achieve optimal load distribution while maintaining restored vertebral body height.
2Shape
If connecting rods are preflexed or pedicle nails are stretched to reduce the fractured vertebra, then vertebral body height is restored, but repeated loosening and re-fastening of pedicle screw nuts is required
Solution Approach 1:
The connecting rods are preflexed during manufacturing to predetermined angles (e.g., 15°, 30°, 45°) based on the degree of vertebral compression. During surgery, the reduction connecting clips are rotated to engage the preflexed rods, automatically achieving reduction without repeated loosening and re-fastening of nuts.
Solution Approach 2:
The one-way gear structure of the reduction connecting clips allows the system to self-adjust and self-lock at the desired reduction position. Once the clips are rotated to engage the preflexed connecting rods, the structure automatically maintains the reduced position without requiring continuous manual adjustment or re-fastening.
3Reliability
If bone grafting is performed through the pedicle, then bone loss is filled and fracture healing is promoted, but the connecting rod blocks the passage of bone grafting
Solution Approach 1:
The connecting rod is positioned in a plane that does not block the anterior-to-posterior passage through the pedicle. By orienting the connecting rod laterally and using reduction connecting clips that engage from the posterior approach, the system creates a spatial separation between the rod's path and the bone grafting path, allowing both procedures to occur simultaneously without interference.
4Ease of operation
If unilateral reduction is performed using one connecting rod, then bone grafting can be performed through the opposite pedicle, but vertebral body height is limited and stress distribution is uneven
Solution Approach 1:
The system uses both upper and lower connecting rods with reduction connecting clips on both sides of the fractured vertebra, allowing simultaneous bilateral reduction and symmetric load distribution. This dual-rod configuration provides multi-functionality by enabling both height restoration and creating space for bone grafting through coordinated adjustment of both rods.
Data Source
AI summary
The present disclosure discloses an internal fixation system for anatomical reduction of a fractured vertebral body of a spine and intravertebral bone grafting. The system includes at least two injured vertebra nails, each of the at least two injured vertebra nails has a reduction connecting clip connected thereto, and all reduction connecting clips are connected by a connecting rod; the reduction connecting clip includes a fixation screw, a reduction connecting nut, and a reduction connecting screw head; and the reduction connecting screw head and the reduction connecting nut are connected to each other and have a one-way gear structure at a joint thereof. The present disclosure maximizes the recovery and maintenance of an effective height of an injured vertebral body, reduces occurrences of postoperative vertebral body collapses and kyphosis, and decreases fractures of pedicle screw nails and the connecting rod.