Retractable Bone Reamer for Anteromedial ACL Tunnel Formation
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Solution Overview
Problem
Current methods for creating bone tunnels, such as those used in ACL reconstruction, face challenges in accurately forming tunnels close to articular cartilage due to inadequate clearance and risk of damage during the drilling process, particularly in the anteromedial approach.
Innovation Solution
A surgical bone reamer with elongate shafts and cutting elements that can be moved between a retracted and non-retracted configuration, allowing for precise alignment and minimization of contact with surrounding structures, thereby reducing the risk of damage and improving tunnel formation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the reamer is inserted through the anteromedial portal with a shallow angle approach, then the femoral tunnel entrance can be located closer to the original ACL attachment site for more anatomical reconstruction, but the guide pin trajectory brings the reamer much closer to articular cartilage, creating inadequate clearance and risk of scraping or damaging the cartilage
Solution Approach 1:
The reamer is designed with a movable second elongate shaft that can be slid along the first elongate shaft to adjust the position of the second cutting element. This dynamic adjustment allows the reamer to change its profile during insertion, enabling safe passage through the anteromedial portal by retracting the second cutting element away from the articular cartilage, while still allowing proper engagement with the guide pin for accurate tunnel formation.
Solution Approach 2:
The reamer is divided into multiple segments including a first elongate shaft with a first cutting element and a second elongate shaft with a second cutting element. The second elongate shaft can be moved independently along the first shaft, allowing the cutting elements to be positioned at different locations. This segmentation enables the reamer to have a low profile when approaching the articular cartilage and a full profile when engaging the guide pin, resolving the clearance problem.
2Reliability
If the reamer is designed with a larger diameter to ensure proper engagement with the guide pin, then reliable tunnel formation is achieved, but the increased diameter creates inadequate clearance when passing through the anteromedial portal close to articular cartilage
Solution Approach 1:
The reamer's diameter is made variable through the movable second elongate shaft mechanism. During insertion through the anteromedial portal, the second elongate shaft is retracted to minimize the reamer's diameter and maximize clearance from the articular cartilage. Once positioned, the second elongate shaft can be extended to engage the guide pin, providing the necessary diameter for reliable engagement and tunnel formation.
Data Source
AI summary
Low profile reamers and methods of use are provided which can, in general, allow a hole to be drilled in bone. In one embodiment, a low profile retractable bone reamer is provided having an elongate shaft with a cutting element disposed on a distal end of the elongate shaft that can be configured to drill a hole in bone. The elongate shaft and cutting element can have first and second longitudinally separated portions that are movably coupled to each other. The reamer can be configured to move between a retracted configuration, in which a the reamer has a reduced, low profile configuration, and a non-retracted configuration, in which both longitudinally separated portions of the cutting element can be positioned adjacent to one another to form a single cutting element.