Flexible Distal Guide Pin for Cartilage-Sparing Femoral Tunnel Placement
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Solution Overview
Problem
Conventional surgical guide pin placement methods, such as the transtibial and anteromedial approaches, face challenges in accurately positioning guide pins without damaging articular cartilage or requiring unnecessary drilling through the tibia, which can lead to suboptimal tunnel placement and increased surgical complexity.
Innovation Solution
A guide pin with a rigid proximal portion and a flexible distal portion, allowing the distal portion to be bent within the intra-articular space to adjust its angle relative to the proximal portion, enabling the guide pin to be placed at a non-zero angle and avoiding contact with articular cartilage, while a cannulated reamer can be advanced over the flexible distal portion to create a femoral tunnel without initial tibial drilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a guide pin is inserted directly into the femur through the intra-articular space using the anteromedial approach, then initial drilling of the tibia is unnecessary, but the trajectory brings the guide pin much closer to articular cartilage, making it challenging to place the reamer without scraping or damaging the cartilage
Solution Approach 1:
The guide pin is divided into three distinct segments: a rigid proximal portion for stable anchoring in the femur, a flexible intermediate portion that can be bent to adjust trajectory, and a rigid distal portion for precise positioning. This segmentation allows the surgeon to navigate around articular cartilage while maintaining procedural simplicity.
Solution Approach 2:
The guide pin incorporates a flexible intermediate portion that can be dynamically bent or flexed within the intra-articular space to adjust the trajectory angle. This dynamic flexibility enables the pin to clear articular cartilage while still achieving the desired femoral tunnel position, resolving the contradiction between simplified approach and cartilage protection.
2Loss of time
If the guide pin is placed at a shallow angle directly into the femur, then tibial drilling is avoided, but the reamer cannot be placed without scraping or damaging the articular cartilage due to inadequate clearance
Solution Approach 1:
The flexible intermediate portion of the guide pin allows dynamic adjustment of the trajectory angle by bending within the intra-articular space. This enables the pin to be inserted quickly without tibial drilling while simultaneously providing adequate clearance for the reamer, preventing cartilage damage without increasing surgical time.
Solution Approach 2:
The guide pin's flexible portion changes the trajectory parameter (angle) dynamically during insertion. By flexing the intermediate portion, the effective insertion angle is adjusted to provide sufficient clearance for the reamer, allowing both time efficiency and cartilage protection to be achieved.
3Ease of operation
If traditional rigid guide pins are used in the anteromedial approach, then placement is straightforward, but the trajectory cannot be adjusted to avoid articular cartilage contact
Solution Approach 1:
The guide pin is segmented into rigid and flexible portions, combining the ease of rigid pin placement with the precision adjustment capability of flexible components. The rigid proximal and distal portions provide stable anchoring and positioning, while the flexible intermediate portion enables precise trajectory adjustment to avoid cartilage and achieve accurate femoral tunnel placement.
Solution Approach 2:
The flexible intermediate portion allows dynamic adjustment of the pin's trajectory angle during insertion. This maintains the ease of direct anteromedial insertion while enabling precise control over the final trajectory to avoid articular cartilage and achieve anatomically correct tunnel placement.
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
This approach reduces the risk of damaging articular cartilage, allows for more anatomically accurate tunnel placement, and simplifies the surgical procedure by avoiding initial tibial tunnel formation, thereby improving the precision and efficiency of guide pin placement and subsequent ligament graft positioning.
Implementation Method 1
a flexible distal portion, allowing the distal portion to be bent within the intra-articular space to adjust its angle relative to the proximal portion
Data Source
AI summary
Methods and devices are provided for placing surgical guide pins, reamers, and ligament grafts into bone. In one exemplary embodiment, the method can include advancing a guide pin that includes a proximal rigid portion and a flexible distal portion. The rigid proximal portion can be advanced into a femoral tunnel such that the flexible distal portion extends across an intra-articular space. The flexible portion of the guide pin can be bent to adjust a distance between the guide pin and articular cartilage. A cannulated reamer can be advanced over the flexible portion of the guide pin and the reamer can be manipulated to avoid contact with the articular cartilage in the intra-articular space. A ligament graft can be secured in the femoral tunnel created by the guide pin and the reamer.