Graft Tunnel Sheath Depth Stop for Accurate Bone Drilling
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Solution Overview
Problem
During arthroscopic ligament reconstruction surgery, it is challenging for surgeons to accurately assess and control the depth of retrograde tunnels in bone, leading to potential misfits between the tunnel and the tissue graft, which can cause subsequent movement or elongation of the graft.
Innovation Solution
A drill assembly system with a slidable sheath featuring a depth stop is used to ensure precise control of tunnel depth, where the sheath is inserted into the antegrade tunnel and the cutting member is deployed until it contacts the sheath's distal end, ensuring the retrograde tunnel is of the correct length for the graft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If retrograde drilling is performed without a depth control mechanism, then the surgical procedure is simpler, but the depth accuracy of the tunnel deteriorates
Solution Approach 1:
A sheath is introduced as an intermediary component between the drill assembly and the bone. The sheath serves as a depth-stop mechanism that limits the penetration depth of the cutting member during retrograde drilling. The sheath is inserted into the antegrade tunnel first, then the cutting member drills until it contacts the sheath, ensuring precise depth control without requiring complex electronic or mechanical depth-measurement systems.
Solution Approach 2:
The sheath is inserted into the antegrade tunnel before the retrograde drilling begins. This preliminary placement of the sheath establishes the depth limit in advance, so that when the cutting member is deployed and drilled retrograde, the depth is automatically controlled by the pre-positioned sheath. This eliminates the need for real-time depth assessment during drilling.
2Measurement precision
If the surgeon estimates tunnel depth by visualization during drilling, then the device is simpler to operate, but the measurement precision deteriorates
Solution Approach 1:
The sheath acts as a physical intermediary that translates the abstract concept of depth into a tangible stop point. Instead of relying on the surgeon's visual estimation and judgment, the sheath provides a mechanical limit that automatically stops the drilling at the correct depth. This converts a subjective measurement task into an objective mechanical constraint.
3Reliability
If the graft is inserted without precise depth control, then the surgical procedure is faster, but the reliability of graft positioning deteriorates
Solution Approach 1:
The sheath is pre-inserted into the antegrade tunnel to establish the depth limit before the retrograde tunnel is created. This preliminary action ensures that when the cutting member drills retrograde, it will automatically stop at the correct depth where the graft needs to be positioned. This eliminates the need for post-drilling depth adjustments or revisions, maintaining surgical efficiency while ensuring reliable graft positioning.
Data Source
AI summary
Methods and devices for consistently and accurately controlling the depth of the graft tunnel. A sheath is inserted into the bone until a stop member on the sheath contacts the bone. A cutting member is then deployed to drill a larger bore in the tunnel until making contact with the distal end of the sheath. The cutting member may be drawn retrograde within the tunnel, or driven antegrade from an opening opposite the opening in which the sheath resides. The drill and the sheath can then be removed, leaving the tunnel that includes a tunnel portion sized to fit a graft so that the graft fits tightly within the tunnel portion and is flush with the opening of the tunnel.