3D Patient Model Registration for Hip Implant Positioning
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Solution Overview
Problem
Current surgical methods face challenges in accurately determining and confirming the proper positioning of components, such as acetabular cups, during surgeries like total hip arthroplasty, due to variations in patient and x-ray device alignment, leading to potential inaccuracies and increased radiation exposure.
Innovation Solution
A system and method utilizing 3D imaging techniques to generate precise models of patients, allowing for the registration of 2D projections and calculation of adjustment factors to achieve target component orientations, thereby reducing the need for repeated x-rays and minimizing patient movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If repeated x-rays are taken to confirm proper component placement, then measurement precision is improved, but patient radiation exposure increases
Solution Approach 1:
The system performs pre-operative 3D imaging (CT or MRI) to create a detailed patient-specific anatomical model before surgery. This preliminary action captures all necessary anatomical information in advance, eliminating the need for repeated intra-operative x-rays to assess component placement. The pre-acquired 3D model serves as a reference for planning and verifying implant positioning without additional radiation exposure during surgery.
Solution Approach 2:
The invention creates a digital 3D copy of the patient's anatomy from pre-operative imaging data. This digital replica allows surgeons to visualize, measure, and plan component placement accurately without needing to repeatedly image the actual patient during surgery. The digital model can be manipulated and analyzed indefinitely without exposing the patient to additional radiation.
2Measurement precision
If the patient is moved to different positions during surgery for x-ray imaging, then component placement can be confirmed, but measurement precision decreases due to position variations
Solution Approach 1:
The system establishes a reference coordinate system and captures anatomical landmarks in a predefined neutral position before any surgical movements occur. All subsequent component placement measurements are referenced back to this initial neutral position, ensuring consistency regardless of patient movement during surgery. The pre-established reference frame allows accurate verification without requiring the patient to return to the exact neutral position.
Solution Approach 2:
The invention transforms the measurement approach by changing from direct 2D x-ray measurements (which require precise patient positioning) to 3D spatial coordinate transformations. The system calculates transformation matrices that account for patient position changes, allowing accurate component placement verification through mathematical transformation rather than requiring physical repositioning to neutral alignment.
3Measurement precision
If multiple x-rays are taken to establish neutral position, then positioning accuracy is improved, but surgical time increases
Solution Approach 1:
The neutral position and anatomical reference points are identified and recorded during pre-operative imaging and surgical planning, before the actual implantation begins. This preliminary establishment of reference data eliminates the time-consuming process of taking multiple intra-operative x-rays to determine neutral position. The reference information is already available from the pre-acquired 3D images.
Solution Approach 2:
The invention replaces the mechanical process of physically positioning and imaging the patient multiple times to establish neutral position with a computational approach. The system uses image processing algorithms to automatically identify anatomical landmarks and calculate neutral position from pre-operative 3D images, eliminating the need for repeated mechanical positioning and x-ray exposure during surgery.
4Adaptability or versatility
If the patient cannot be returned to neutral position after surgery, then surgical flexibility is improved, but measurement precision deteriorates
Solution Approach 1:
The system changes the measurement paradigm from requiring physical return to neutral position to using mathematical transformation parameters. By calculating transformation matrices that represent the relationship between the neutral position and the current surgical position, the system can accurately verify component placement even when the patient remains in a non-neutral position throughout surgery. The measurement is performed in the transformed coordinate space rather than requiring physical repositioning.
Solution Approach 2:
The invention transitions from 2D x-ray measurement plane (which requires neutral positioning) to 3D spatial coordinate system. In this three-dimensional framework, the system can define and measure component placement accuracy relative to the neutral position regardless of the patient's current orientation. The additional dimensional information allows accurate measurement without requiring the patient to physically return to the reference position.
Data Source
AI summary
Disclosed herein are a system and method that may help place or position a component, such as an acetabular cup or a femoral component, during surgery. An example system may iteratively register a plurality of two-dimensional projections from a three-dimensional model of a portion of a patient, the three-dimensional model being generated from a data set of imaging information obtained at a neutral position. An example system may further score each two-dimensional projection against an intra-operative image by calculating a spatial difference between corresponding points. A two-dimensional projection having a minimum score reflecting the smallest distance between the corresponding points may be identified. Using the two-dimensional projection having the minimum score, an adjustment score reflecting a difference in the values representing the orientation of the three-dimensional model at the intra-operative projection position and values representing the orientation of the three-dimensional model at the neutral position may be calculated.