Graft Tunnel Drilling With Sheath-Based Depth Control
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Solution Overview
Problem
Surgeons face challenges in accurately assessing the depth of retrograde tunnels during arthroscopic ligament reconstruction surgery, 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 with a sheath featuring a depth stop is used to ensure precise control of tunnel depth, where the sheath is inserted into the antegrade tunnel until the stop member contacts the bone, and the cutting member is deployed to create a retrograde tunnel of the desired length, ensuring a tight fit for the graft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If retrograde drilling is performed without a depth stop mechanism, then the surgical procedure is simpler, but the depth control precision deteriorates leading to misfit between tunnel and graft
Solution Approach 1:
A sheath is introduced as an intermediary component between the drill assembly and the bone. The sheath includes a depth stop member that physically limits the penetration depth of the cutting member during retrograde drilling. This intermediary mechanism provides precise depth control without requiring complex electronic sensors or automated control systems, thus resolving the contradiction between precision and complexity.
Solution Approach 2:
The sheath is pre-positioned in the antegrade tunnel before retrograde drilling begins. The depth stop member is预先 set at the correct position along the sheath based on the desired tunnel depth. This preliminary positioning ensures that when retrograde drilling occurs, the depth is automatically controlled by the pre-established mechanical stop, achieving precision without complex real-time control systems.
2Measurement precision
If the surgeon estimates tunnel depth by visualization during drilling, then the device remains simple, but the measurement precision deteriorates causing graft misfit
Solution Approach 1:
The sheath with the depth stop member performs the measurement function automatically during the drilling process itself. As the cutting member advances during retrograde drilling, it naturally stops when it reaches the depth stop member, providing self-measuring depth control. This eliminates the need for separate measurement steps or complex visualization techniques, maintaining ease of operation while achieving high measurement precision.
3Reliability
If the graft is inserted without precise depth control, then the surgical time is reduced, but the reliability deteriorates causing graft movement or elongation
Solution Approach 1:
The tunnel creation process is segmented into two distinct phases: antegrade drilling to create the initial passage, and retrograde drilling with depth control to create the precise graft receiving tunnel. The sheath with depth stop member is specifically used in the second phase to ensure precise depth control. This segmentation allows the majority of the surgical procedure to proceed efficiently while only the critical depth-determining step requires the additional controlled mechanism, thus maintaining overall surgical efficiency while ensuring graft stability.
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.