Bone Anchor Compression for Fixation Without Cortical Wall Penetration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bone anchors used for spinal deformity correction often fail to provide adequate fixation due to inadequate purchase in cancellous bone, leading to undesirable movement and recurrence of spinal deformities, and existing designs that extend through the vertebral body risk damaging the cortical wall.
Innovation Solution
The development of bone anchors with an inner chamber and opposing thread forms that compact cancellous bone, creating a compressed region for enhanced fixation without penetrating the cortical wall, mimicking bicortical purchase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bone anchors are extended through the vertebral body to provide bicortical purchase, then fixation strength is improved, but risk of damaging the cortical wall increases
Solution Approach 1:
The patent applies partial action by creating a compressed bone region that extends the functional length of the anchor without requiring complete penetration through the distal cortical wall. The anchor achieves sufficient fixation strength through the compressed cancellous bone region alone, eliminating the need for excessive action (full bicortical purchase) and its associated risks.
2Object-affected harmful factors
If bone anchors are shortened to avoid cortical wall penetration, then safety is improved, but fixation strength in cancellous bone deteriorates
Solution Approach 1:
The patent changes the physical state of the cancellous bone by compressing it to create a denser, more stable region. This parameter change (from normal density to compressed density) allows the anchor to achieve sufficient fixation strength with a shorter length, improving safety while maintaining or enhancing fixation capability.
Solution Approach 2:
The patent performs preliminary action by pre-compressing the cancellous bone along the anchor's path before final anchor insertion. This pre-compression creates a favorable bone density distribution that enhances anchor purchase, allowing shorter anchors to achieve the fixation strength previously requiring longer bicortical anchors.
3Strength
If anchor length is increased to improve fixation, then fixation strength is improved, but risk of cortical wall penetration and damage increases
Solution Approach 1:
The patent eliminates the need for precise length control by using partial action - the compressed bone region provides sufficient fixation before the anchor reaches the distal cortical wall. This removes the complexity of precisely controlling anchor length to achieve bicortical purchase without penetration, as the compressed region naturally limits the effective anchor length.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides increased fixation strength and stability by extending the functional length of the anchor into the bone, reducing the risk of anchor dislodgment and enhancing the efficacy of spinal correction procedures.
Implementation Method 1
compact the cancellous bone and/or to advance bone in front (distally) of the anchor as it is advanced to create a compressed bone region in front of the anchor
Data Source
AI summary
Methods for bone correction and/or fixation of bone anchors, such as spinal deformity correction. In some implementations, the method may comprise advancing a bone anchor through a proximal bone wall and into a bone. Bone material may be compressed in a region distal of the bone anchor by advancing the bone anchor within the bone to form a compressed bone region, the compressed bone region extending, at least in part, distally of the bone anchor, and in some cases within an inner chamber of the bone anchor. The compressed bone region may increase the fixation strength of the bone anchor within the bone to decrease the chances of the bone anchor becoming dislodged within the bone. In some cases, the compressed bone region may be advanced to and/or compressed against a distal cortical bone to obtain functional bicortical purchase without penetration of the cortical bone.