Orthognathic Surgery Positioning Guide for Skeletal Alignment
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Solution Overview
Problem
Current orthognathic surgery techniques rely on subjective and error-prone methods for positioning osteotomized skeletal segments relative to the uncut facial skeleton, particularly due to the instability of the mandible and reliance on Centric Relation, which complicates precise repositioning and fixation during surgery.
Innovation Solution
A surgical positioning apparatus and system that uses pre-defined skeletal reference points marked by positioning guides and occlusal splints to accurately align and fix osteotomized segments, eliminating the need for Centric Relation by utilizing pre-osteotomy and post-osteotomy guides to ensure precise three-dimensional positioning and fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods using Centric Relation and manual positioning are used, then the surgical procedure can be performed with basic equipment, but the positioning precision and reliability are compromised due to mandible instability and subjective error
Solution Approach 1:
Skeletal reference points are pre-defined and marked on the patient's facial skeleton before osteotomy through positioning guides. These reference points are determined from pre-operative imaging data and surgically marked at their exact locations, so that when the osteotomized segment is later repositioned, it can be accurately aligned to these pre-established points without relying on unstable Centric Relation
Solution Approach 2:
Positioning guides and occlusal splints serve as intermediary devices that transfer the pre-defined skeletal reference points to the osteotomized segment. The positioning guide aligns with the reference points and provides physical guidance for repositioning, while the occlusal splint ensures proper dental relationship, creating a reliable intermediary system that eliminates the need for direct manual positioning
2Reliability
If manual positioning using Centric Relation is used, then the operative time can be reduced without complex equipment, but the reliability and accuracy of skeletal segment positioning deteriorate due to human error and mandible mobility
Solution Approach 1:
All positioning reference points and alignment criteria are predetermined from pre-operative CT and dental model data. The positioning guide is fabricated beforehand with precise geometric features that match these reference points, eliminating the need for intraoperative manual positioning and Centric Relation determination, thereby maintaining reliability while reducing operative time
Solution Approach 2:
The positioning system incorporates feedback mechanisms where the positioning guide must physically align with the pre-marked skeletal reference points and the occlusal splint must achieve proper dental contact. This provides immediate feedback on positioning accuracy, ensuring reliable placement without requiring extended manual adjustment and verification time
3Manufacturing precision
If pre-operative digital planning is used, then the surgical plan accuracy is improved, but the ability to translate this plan to intra-operative positioning is compromised due to lack of stable reference points
Solution Approach 1:
The pre-operative digital planning identifies and marks the exact locations of skeletal reference points on the patient's facial skeleton. These reference points are then physically marked during surgery using the positioning guide, creating a direct link between the digital plan and the actual surgical field. This preliminary marking action enables accurate translation of the digital surgical plan to intra-operative positioning
Solution Approach 2:
The positioning guide acts as an intermediary device that embodies the digital surgical plan in physical form. It contains geometric features and alignment references that correspond to the pre-operative planning data, serving as a bridge between the virtual surgical plan and the actual surgical execution, thereby enabling precise translation of planning accuracy to intra-operative positioning accuracy
Data Source
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AI summary
A skeletal positioning method (400) and apparatus (10, 100, 200, 300) includes a splint (12, 202) having a main body (18, 208) coupled to a skeletal structure (14, 204) of a patient and a positioning guide (16, 104, 206, 304) having a skeletal footplate (24, 106, 214, 306), a splint footplate (26, 108, 216, 308), and an arm (28, 110, 218, 310) coupling the skeletal footplate and the splint footplate, the skeletal footplate including at least one aperture (30, 114, 220, 314) formed therein and the splint footplate including a means for releasably coupling (32, 1 16, 222, 316) the positioning guide to the splint, wherein a relative position and orientation of the skeletal footplate and the splint footplate is pre-determined to align a portion of the skeletal footplate with a pre-defined portion of the skeletal structure of the patient.