Facet-Based Angular Adjustment Mechanism for Surgical Alignment
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Solution Overview
Problem
Existing angular adjustment mechanisms in orthopaedic surgery, such as those described in WO-A-2009/037471, are limited by the size of the adjustment member, which restricts the number of slots and thus the range of angular adjustment, often providing increments of 2 degrees or greater, making finer adjustments difficult.
Innovation Solution
The use of facets on the adjustment member that engage corresponding surfaces in a recess on a pivoting member allows for a secure connection without the need for intermediate walls or edges, enabling a greater range of angular adjustment and simpler operation, with facets defining different angled axes that can be rotated to set the angle of the pivoting member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If slots are used on the adjustment member to define angular positions, then the mechanism provides discrete angular adjustment, but the number of slots is limited by the size of the adjustment member, restricting the range of adjustment
Solution Approach 1:
The invention transitions from using discrete slots (one-dimensional arrangement) to using facets on the circumferential surface (two-dimensional arrangement). The facets are distributed around the circumference, allowing multiple angular positions to be defined within the same radial space, effectively increasing the adjustment range without increasing the overall size of the adjustment member.
Solution Approach 2:
The adjustment member's surface is segmented into multiple facets, each defining a different angular position. This segmentation allows the mechanism to provide multiple discrete angular adjustments (e.g., 0°, 5°, 10°, 15°) without requiring a large number of slots, as each facet can be positioned around the circumference to define a unique angular orientation.
2Reliability
If walls are added to define recesses for engagement, then secure connection is achieved, but the mechanism becomes more complex and harder to clean
Solution Approach 1:
The invention extracts the intermediate walls from the recess structure, leaving only the essential engagement surfaces. The facets on the adjustment member engage directly with corresponding surfaces in the recess without requiring walls to define the recess boundaries, simplifying the overall structure while maintaining secure connection through the facet-surface engagement.
Solution Approach 2:
Instead of defining the recess with walls and having the adjustment member fit into it, the invention inverts the approach by placing facets on the outside of the adjustment member that protrude to engage with surfaces in the recess. This external facet approach eliminates the need for complex internal wall structures while achieving reliable engagement.
Data Source
AI summary
An angular adjustment mechanism for a surgical instrument is described. The mechanism comprises an adjustment member (102) configured for rotation about a longitudinal axis (122), the adjustment member comprising a plurality of pairs of facets (134) arranged about the longitudinal axis. Each of the plurality of pairs of facets defines a respective angled axis (148B,148C) at an angle (150B,150C) relative to the longitudinal axis. A pivoting member (104) is arranged to pivot about a pivot axis perpendicular to the longitudinal axis and comprises a recess (128) for receiving the adjustment member and engaging one pair of the plurality of pairs of facets. This provides an angular adjustment mechanism in which facets on the outside of the adjustment member engage corresponding surfaces in a recess on a pivoting member. The use of facets provides a secure connection while allowing a greater degree of angular adjustment and providing a further benefit of simple operation.