Intra-Operative Tibial Cutting Guide Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cutting guides for orthopaedic procedures, such as bi-cruciate retaining total knee arthroplasty, face challenges in allowing precise intra-operative adjustments, as they typically fix all degrees of freedom simultaneously, leading to potential errors and limitations in aligning resection slots with the tibial eminence.
Innovation Solution
A tibial cutting guide with a patient-matched upper and lower portion, featuring adjustable pin slots and resection slots, allows for intra-operative adjustments in specific degrees of freedom by sliding along alignment pins, enabling fine-tuning of the guide's position and orientation relative to the tibial eminence, with optional removable pin guide limiters for varying constraint levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a cutting guide fixes all degrees of freedom simultaneously, then the guide is stable and easy to position, but it cannot be adjusted intra-operatively to achieve precise alignment with the tibial eminence
Solution Approach 1:
The cutting guide transitions from a static fully-constrained design to a dynamic partially-constrained design. The guide initially contacts the tibial surface at multiple points to provide stability, then allows controlled movement in specific degrees of freedom (rotation and translation) after pin insertion, enabling intra-operative adjustment for precise alignment while maintaining overall positional stability.
2Adaptability or versatility
If a cutting guide allows free movement for adjustment, then it is flexible and adaptable, but it lacks stability and may shift position during the procedure
Solution Approach 1:
The guide employs dynamic constraint where the degree of freedom is selectively released. Initially, multiple contact points on the tibial surface provide full constraint for stability. After pin insertion through the slots, the guide is permitted to adjust in rotation and translation degrees of freedom while maintaining contact with the bone surface, achieving a balance between stability and adjustability throughout the procedure.
Solution Approach 2:
The constraint system is segmented into different phases: initial placement with full constraint for stability, then selective release of specific degrees of freedom for adjustment, and final fixation. The pin slots are segmented to allow movement only in specific directions while maintaining contact in other directions, enabling controlled adjustment without complete loss of stability.
3Measurement precision
If a cutting guide uses patient-matched surfaces to restrain position, then initial positioning is accurate, but subsequent adjustment is limited
Solution Approach 1:
The patient-matched surfaces provide accurate initial positioning by conforming to the unique tibial anatomy. The guide is designed with pin slots that allow controlled movement after pin insertion, enabling the surgeon to adjust the guide's position and orientation while maintaining the benefits of the patient-matched initial alignment. This dynamic design permits fine-tuning of the resection slots' alignment with the tibial eminence.
Data Source
AI summary
A tibial cutting guide includes upper and lower portions having patient-matched surfaces. The upper portion defines resection slots for forming resections about the tibial eminence. The lower portion defines two pin slots for receiving alignment pins such that in use the position of the resection slots relative to the tibial eminence can be adjusted by sliding the cutting guide along the alignment pins placed in the tibia through the pin slots. The lower portion defines a resection slot for guiding a saw blade to form a horizontal plateau resection, and two pin holes for receiving fixation pins. A method includes positioning a patient-matched cutting guide on the proximal tibia; intra-operatively adjusting the position of the cutting guide in two degrees of freedom by sliding the cutting guide along fixation pins placed in the tibia; and resecting the tibia about the tibial eminence.