Trial Femoral Head Alignment for Accurate Cup Orientation
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Solution Overview
Problem
Existing methods for assessing acetabular cup orientation during hip surgery are inaccurate and difficult to reproduce, particularly in minimally invasive procedures, due to limited access and variability in surgical techniques.
Innovation Solution
A femoral trialling kit with a trial femoral head and neck featuring anti-rotation features and a visual alignment guide, allowing for precise angular configuration adjustment to facilitate accurate acetabular cup orientation assessment in both right and left hip joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If anatomical approaches are used to gauge acetabular cup orientation by inspection or instrumentation, then the surgeon can assess orientation, but accuracy is limited due to limited access in minimally invasive approaches
Solution Approach 1:
The patent introduces an intermediary measurement system consisting of indicators on the trial femoral head and corresponding reference markings on the acetabular cup. These intermediaries transmit orientation information from the difficult-to-access surgical site to the visible external environment, allowing accurate assessment without requiring direct visual access to the cup-bone interface
Solution Approach 2:
The patent replaces the manual mechanical inspection method (surgeon visually gauging orientation through limited access) with an optical indication system. The indicators and markings create visible alignment references that can be observed externally, substituting the need for direct mechanical access and visual estimation
2Measurement precision
If markings or features on trial components are used to gauge angular orientation, then orientation can be assessed, but the methods are difficult to reproduce and vary between surgeons
Solution Approach 1:
The patent employs color-coded indicators and markings on the trial components. Different colors or contrasting markings provide unambiguous visual references for orientation assessment, eliminating subjective interpretation variations between surgeons and ensuring consistent, reproducible measurement across different operators
Solution Approach 2:
The orientation indicators and reference markings are pre-configured on the trial components during manufacturing. This preliminary setup ensures that the measurement system is already calibrated and ready for use, eliminating the need for surgeons to perform complex alignment procedures or subjective assessments during surgery, thereby improving reproducibility
3Measurement precision
If internal rotation of the femur is applied to assess cup orientation (Ranawat sign), then combined anteversion can be determined, but knee laxity or deformity can influence the interpretation
Solution Approach 1:
The patent extracts the orientation measurement function from the complex Ranawat sign maneuver (which requires femoral rotation and interpretation influenced by knee conditions) and places it directly on the acetabular cup and femoral head components. This separation eliminates the need for femoral rotation and removes the confounding influence of knee laxity or deformity from the measurement process
Data Source
AI summary
A femoral trialling kit and method for assessing acetabular cup orientation during a left hip joint surgical procedure and a right hip joint surgical procedure are described. The kit includes a trial femoral head having an inner wall defining a cavity extending along a head axis and a visual alignment guide on an outer surface of the trial femoral head and a trial femoral neck having a taper at a free end, the taper being receivable within the cavity. One of the taper and the inner wall has a first anti-rotation feature and a second anti-rotation feature, the first anti-rotation feature and the second anti-rotation feature being inclined, and the other of the taper and the inner wall has a third anti-rotation feature. The trial femoral head is attachable to the trial femoral neck in a first angular configuration corresponding to a right hip joint, in which the third anti-rotation feature and the first anti-rotation feature engage, and a second angular configuration corresponding to a left hip joint, wherein the third anti-rotation feature and the second anti-rotation feature engage.