Cable Fixator for Acetabular Fracture Stabilization
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Solution Overview
Problem
Acetabular fractures with medial displacement patterns, particularly those involving the quadrilateral surface, are challenging to treat due to deep pelvic location, limited bone stock, and difficulty in achieving stable internal fixation using standard plates and screws, often resulting in screw cut-out issues.
Innovation Solution
A cable fixation device comprising a clamp and clamping ring that securely accommodates a cable or wire, allowing for tensioning and stabilization of a buttress plate over the fractured surface, providing a mechanical solution for securing bone fixation devices to thin bone structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard plates and screws are used for fixation, then the fixation structure is simple and easy to apply, but the fixation stability is insufficient and screw cut-out occurs due to limited bone stock
Solution Approach 1:
The patent employs a cable (flexible element) that passes through the bone and is secured with a clamp, replacing rigid screws with a flexible tensioning system. This allows distribution of forces along the cable rather than concentrating stress at screw-bone interfaces, preventing cut-out in thin bone structures while maintaining fixation stability
Solution Approach 2:
The invention changes the mechanical parameters of fixation by transitioning from point-based screw fixation to line-based cable fixation. The cable distributes load along its length, changing the stress distribution pattern from concentrated to distributed, which improves reliability in limited bone stock without requiring complex multi-component structures
2Ease of manufacture
If forces are applied at 90° to screw axis for fixation, then the fixation mechanism is simple, but screw cut-out occurs when bone thickness is limited
Solution Approach 1:
Instead of applying forces perpendicular to the fixation element (as with standard screws), the cable fixation system applies forces along the longitudinal axis of the cable through tension. The clamp secures the cable by compressing it radially, inverting the traditional screw mechanism where axial compression prevents pull-out
Solution Approach 2:
The clamp acts as an intermediary component that converts the simple cable insertion into a secure fixation. The clamp provides the mechanical advantage needed to grip the cable and transfer loads effectively, simplifying the overall application process while ensuring reliable fixation in thin bone
3Reliability
If a medial buttress plate is applied across the quadrilateral surface, then the prevention of femur head penetration is improved, but the surgical difficulty increases due to limited access and thin bone structures
Solution Approach 1:
The cable system provides the necessary buttressing function without requiring a rigid plate that would be difficult to access and position. The flexible cable can be routed through minimally invasive approaches, secured with a clamp, and tensioned to provide medial support, maintaining reliability while improving surgical accessibility
Solution Approach 2:
The invention extracts the essential function of the buttress plate (providing medial support to prevent femur head penetration) and implements it through a simplified cable-clamp construct. This removes the complexity of plate positioning and fixation while preserving the mechanical support function through cable tension
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 cable fixation device enables effective stabilization of acetabular fractures by distributing forces more evenly, reducing the risk of screw cut-out and improving bone healing outcomes, even in areas with limited bone stock.
Implementation Method 1
a portion of the clamp is movable between a first configuration and a second configuration, the cable slidable therethrough in the first configuration, the portion of the clamp moving radially inward in the second configuration to clamp the cable
Data Source
AI summary
A cable fixation device comprises a clamp including a head portion and a body portion along with a lumen extending therethrough. The head portion is removably coupleable with an actuating mechanism. The lumen is sized and shaped to slidably accommodate a cable in combination with a clamping ring including a channel extending therethrough. The channel includes a first portion and a second portion. The first portion is sized and shaped to slidably accommodate the cable therethrough. The second portion is sized and shaped to engage the clamp. A portion of the clamp is movable between a first configuration and a second configuration, the cable slidable therethrough in the first configuration. The portion of the clamp moves radially inward in the second configuration to clamp the cable.