ACL Reconstruction Reamer with Staged Cutting Heads
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Solution Overview
Problem
Current ACL reconstruction techniques face challenges such as malpositioning of the guide wire, rotational instability, and difficulties in forming dual diameter femoral passages, leading to issues like tunnel length reduction, articular cartilage damage, and increased risk of guide wire breakage and metallosis.
Innovation Solution
A novel ACL reconstruction method involving drilling a straight tibial passage and a straight femoral passage angled with respect to the tibial passage, using a reamer with a distal and proximal cutting head of different diameters to form dual diameter passages in a single pass, and a guidewire configuration that maintains alignment with the reamer to reduce misalignment and breakage risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the transtibial technique is used to drill a tibial passage for guide wire insertion, then the procedure is straightforward, but the guide wire cannot be positioned at the appropriately native ACL insertion point on the femur, leading to malpositioning and rotational instability
Solution Approach 1:
A curved guide wire is introduced as an intermediary tool that can navigate the anatomical pathway from the tibial tunnel to the native ACL insertion point on the femur. The curvature allows the guide wire to follow the natural bone architecture rather than requiring a direct linear path, thereby achieving accurate positioning while maintaining procedural simplicity
Solution Approach 2:
The solution transitions from a two-dimensional planar drilling approach to a three-dimensional curved pathway. By introducing a curved guide wire that follows the complex spatial geometry of the knee joint, the system achieves accurate 3D positioning at the native ACL insertion point while maintaining ease of operation through the tibial tunnel approach
2Manufacturing precision
If the anteromedial portal technique is used with an offset guide to position the ACL insertion point, then positioning accuracy is improved, but hyperflexion of the knee is required which causes loss of visual reference to anatomical landmarks and may be impossible due to patient anatomy
Solution Approach 1:
Instead of approaching the problem from the anterior medial portal requiring knee hyperflexion, the invention inverts the approach by using the posterior lateral portal which allows the knee to remain in a more neutral position. This maintains visual reference to anatomical landmarks while achieving accurate positioning through the curved guide wire that navigates the appropriate pathway
3Manufacturing precision
If the anteromedial portal technique is used, then ACL insertion point positioning is improved, but shorter tunnel lengths are formed resulting in reduced tendon ingrowth distance and compromised fixation strength
Solution Approach 1:
The curved guide wire enables the femoral passage to follow a three-dimensional pathway through the bone rather than a straight linear path. This curved trajectory increases the effective length of the femoral passage and tendon ingrowth distance while maintaining accurate positioning at the native ACL insertion point, thereby improving fixation strength
4Adaptability or versatility
If flexible drills are used to form dual diameter femoral passages in two passes, then the ability to create varying diameters is achieved, but the drills suffer from breakage and metallosis inducing friction when drilled over the guide wire
Solution Approach 1:
The invention merges the formation of dual diameter femoral passages into a single drilling pass using a staged reamer with multiple cutting surfaces. This eliminates the need for multiple flexible drills and guide wires, thereby reducing the cumulative risk of breakage and metallosis while maintaining the ability to create the required dual diameter configuration for endobutton fixation
5Manufacturing precision
If guide wires are made very flexible to navigate the drilling path, then positioning capability is improved, but friction and risk of breakage increase due to contact with lateral cortex of the femur
Solution Approach 1:
The guide wire is made sufficiently flexible to navigate the required pathway to the ACL insertion point, but not excessively flexible. The flexibility is optimized to the minimum necessary degree to achieve positioning accuracy, thereby reducing unnecessary contact with the lateral cortex and minimizing friction and breakage risk
6Manufacturing precision
If cannulated reamers are used to form dual diameter passages in two passes, then the required passage geometry is achieved, but the procedure is time-consuming requiring detachment and replacement of reaming components
Solution Approach 1:
The invention combines the formation of both diameter sections of the femoral passage into a single drilling operation using a staged reamer with integrated cutting surfaces. This eliminates the need for sequential detachment and replacement of reaming components, thereby maintaining precise dual diameter geometry while significantly improving procedural efficiency and productivity
Data Source
AI summary
There is provided herein and improved anterior cruciate ligament reconstruction technique which comprises drilling a guide wire straight through a tibial passage and then at an angle from an ACL insertion point straight through a femoral passage. A reamer is then attached to a proximal end of the guidewire. The reamer has a distal cutting head, a distal flexible shaft, a proximal cutting head and a proximal flexible shaft. The proximal cutting head has a greater diameter than that of the distal cutting head. The reamer is drilled to follow the guidewire until the distal cutting head passes through the femoral cortex. The reamer is then retrieved at a proximal end thereof, thereby having created a larger diameter medial passage portion and a smaller diameter lateral passage portion within the femoral passage in a single pass, thereafter being ready for insertion of a graft, including by endobutton fixation.