Screw-Clamp Orthopedic Apparatus for Spinal Stabilization
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Solution Overview
Problem
Current spinal instrumentation, such as pedicle screw constructs, faces challenges including high risks of neurological or vascular injury due to malpositioning, pseudoarthrosis, and complications in elderly patients with osteoporosis, along with increased radiation exposure from intraoperative CT scans and risks of proximal junctional kyphosis.
Innovation Solution
A screw-clamp apparatus with a first and second clamp component, each featuring hooks and a bone-screw hole, along with a length-adjusting mechanism, designed to attach to the thoracic vertebrae, providing a claw-like grip without the risks associated with pedicle screws, allowing for realignment and stabilization of the spine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pedicle screw constructs are used for spinal instrumentation, then construct rigidity and scoliosis correction are improved, but the risk of neurological or vascular injury due to malpositioning increases
Solution Approach 1:
The patent introduces a rod-within-rod construction with flexible intermediate elements that act as mediators between the pedicle screws and the spinal column. This intermediate flexible rod system allows for stress distribution and micromotion accommodation, reducing the direct load and potential damage from rigid screw fixation while maintaining overall construct stability and correction capability.
Solution Approach 2:
The invention changes the mechanical parameters of the spinal construct by incorporating flexible rod elements with specific elasticity values and damping characteristics. This allows the system to transition from a purely rigid fixation to a semi-flexible construct that can accommodate physiological movements and reduce stress concentrations at screw-bone interfaces, thereby lowering the risk of malpositioning injuries.
2Measurement precision
If multiple intraoperative CT scans are used for image guidance, then navigation precision is improved, but radiation exposure increases
Solution Approach 1:
The patent employs pre-bent rods with predetermined curvature and flexibility characteristics that are designed before surgery based on patient-specific planning. This preliminary preparation reduces the need for multiple intraoperative adjustments and CT scans, as the rods are pre-configured to achieve the desired spinal alignment, thereby minimizing radiation exposure while maintaining navigation precision.
3Strength
If pedicle screws are used in osteoporotic patients, then fixation strength is improved, but the risk of screw pullout increases
Solution Approach 1:
The flexible rod-within-rod construction acts as a counterbalancing element that distributes mechanical loads away from the pedicle screws. The flexible intermediate rods absorb and redistribute stresses through elastic deformation, reducing the pullout forces experienced by screws in osteoporotic bone, thereby maintaining fixation strength while lowering the risk of screw failure.
Solution Approach 2:
The patent incorporates flexible rod elements with predetermined damping characteristics that provide beforehand cushioning against load spikes and mechanical stresses. This pre-configured shock absorption capacity protects the screw-bone interface in osteoporotic patients by dissipating forces before they can cause screw pullout, while maintaining overall construct stability.
Data Source
Figure 1A~1B
Figure 2~3
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AI summary
A screw-clamp apparatus is disclosed that may include a first clamp component comprising a first attachment end and at least one hook on a first hook end, a second clamp component comprising a second attachment end and at least one hook on a second hook end, a bone-screw hole located in one of the first clamp component and the second clamp component, a bone screw configured to be inserted through the bone-screw hole and to be inserted into bone, a first spacer-receiver located on one of the first clamp component and the second clamp component, and a length-adjusting mechanism configured to adjust a longitudinal length of the screw-clamp apparatus. The first attachment end and the second attachment end are configured to attach the first clamp component and the second clamp component together. The first spacer-receiver is configured to secure a spacer.