Patient-Specific Glenoid Reaming Guide for Shoulder Arthroplasty
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Solution Overview
Problem
In shoulder arthroplasty procedures, accurately locating and fixing prostheses and fixation screws to the scapula in a preoperatively planned position and orientation is challenging, leading to potential misalignment and failure of joint replacement.
Innovation Solution
The method involves scanning the patient's anatomy to design patient-specific guides that interface directly with the glenoid and baseplate, using a first guide for optimal baseplate placement and a second guide for screw fixation, ensuring reproducible alignment and fixation of the baseplate to the glenoid with preoperatively planned trajectories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional alignment methods are used for baseplate placement, then the surgical procedure is simpler, but the alignment precision and reproducibility deteriorate
Solution Approach 1:
Patient-specific guides are designed and manufactured before surgery based on preoperative imaging data. The guides incorporate pre-planned trajectories for baseplate placement and screw fixation, allowing the alignment decisions to be made beforehand when optimal positioning can be carefully determined, rather than relying on intraoperative estimation.
Solution Approach 2:
The patient-specific guides act as intermediary devices between the preoperative planning stage and the actual implantation. These guides translate the virtual surgical plan into physical alignment references, mediating the transfer of precise alignment information from computer models to the actual surgical field through tactile and visual cues.
2Reliability
If fixation screws are inserted without preplanned trajectories, then the surgical procedure is faster, but the reliability of fixation deteriorates
Solution Approach 1:
The optimal trajectories for fixation screws are determined during preoperative planning, allowing the surgical team to identify the best paths that avoid critical structures and achieve optimal purchase in the glenoid bone. The guides preserve these pre-determined trajectories during the actual surgery.
Solution Approach 2:
The guide system provides localized alignment references at specific critical points - the baseplate placement site and the screw insertion sites. Rather than requiring overall system complexity, the guides concentrate alignment functionality where it is most needed: at the interface between the baseplate and glenoid, and at the screw-bone interface.
3Manufacturing precision
If patient-specific guides are used for baseplate placement, then the alignment accuracy improves, but the manufacturing complexity and cost increase
Solution Approach 1:
The guides are manufactured in advance based on digital models derived from patient-specific imaging data. This preliminary manufacturing allows for precise fabrication using modern additive manufacturing or CNC techniques, ensuring that the physical guides accurately reflect the virtual surgical plan without requiring complex manual adjustments during surgery.
Data Source
AI summary
Disclosed herein are systems and methods for securing a glenoid baseplate to a resected glenoid cavity in a preoperatively planned position. Image information obtained from the glenoid cavity and surrounding scapula is analyzed to determine the location of optimal bone stock. A guide is designed based on the image information, the guide having a patient specific contact surface that contacts a surface of the bone in a preoperatively planned position. The guide is designed to have a cannulated portion including a specific length. A marking pin having at least one reference feature is drilled into the glenoid cavity. The length of the cannulated portion of the guide is based on a location of the at least one reference feature on an outer surface of the marking pin. A cannulated reamer guided by the marking pin is then used to resect the glenoid cavity until a stop surface of the cannulated reamer contacts an end of the marking pin.