Universal Patient-Specific Knee Arthroplasty Cutting Guides
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Solution Overview
Problem
Current surgical techniques for total knee arthroplasty (TKA) face challenges due to the limitations of conventional instrumentation, which can lead to inaccuracies, increased operative time, and complications such as bleeding and fat embolism. Additionally, the high cost and company-specific nature of patient-specific instruments (PSI) limit their widespread application.
Innovation Solution
The development of patient-specific instruments (PSI) for TKA, which utilize image-based preoperative planning and computer-aided manufacturing to create custom surgical guides that can replace conventional instrumentation systems. These instruments are designed to improve accuracy and reduce complications by providing precise cutting guides and alignment tools tailored to individual patient anatomy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional instrumentation systems are used for TKA surgery, then the surgical procedure can be performed with standardized tools, but the accuracy of bone cutting and implant alignment deteriorates
Solution Approach 1:
The conventional complex instrumentation system is segmented into patient-specific cutting guides and blocks that are customized for each patient's anatomy. Each guide is designed based on preoperative imaging data to match the specific geometric features of the patient's bone surfaces, eliminating the need for complex standardized instrumentation while improving measurement and cutting accuracy.
Solution Approach 2:
Patient-specific cutting guides and blocks are designed and manufactured before surgery based on preoperative CT or MRI scans. The virtual surgery is planned in advance, and the physical guides are produced using rapid prototyping or CNC machining, allowing the actual surgical procedure to execute the pre-planned accurate cuts without requiring complex intraoperative instrumentation.
2Productivity
If conventional instrumentation with multiple jigs and fixtures is used, then standardized surgical procedures can be performed, but the assembly time and operative duration increase
Solution Approach 1:
The patient-specific cutting guides and blocks serve multiple functions: they act as alignment guides, depth stop blocks, and cutting path guides all in single components. Each patient-specific instrument is designed to perform the specific tasks required for that patient's anatomy, replacing multiple standardized jigs and fixtures with fewer customized tools, thereby reducing assembly time and operative duration.
3Measurement precision
If alignment guides that violate the IM canal are used, then implant alignment can be achieved, but the risk of bleeding, infection, and fat embolism increases
Solution Approach 1:
The invention extracts the alignment function from instruments that penetrate the intramedullary canal and relocates it to external patient-specific cutting guides and blocks. These guides achieve precise implant alignment by matching external geometric features of the patient's bone surfaces visible on preoperative imaging, eliminating the need to violate the IM canal and thereby removing the associated risks of bleeding, infection, and fat embolism.
4Measurement precision
If company-specific patient specific instruments are produced, then accuracy for that specific implant can be improved, but the cost and inventory complexity increase
Solution Approach 1:
The patient-specific cutting guides and blocks are designed with universal compatibility features that allow them to work with different implant systems. The guides are customized to each patient's anatomy and implant size requirements, but the underlying design methodology and geometric matching principles can be applied across different implant companies and prosthesis types, reducing inventory complexity and enabling broader applicability.
Data Source
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Figure 1-E~1-F
AI summary
Total knee arthroplasty is the standard treatment for advanced knee osteoarthritis. A new device and method of patient specific instruments (PSI) was first reported by Hafez et al1-3 in 2004 & 2006 followed by commercialization by several implant manufacturers that produce PSI exclusively for their own knee implants. Therefore, these PSI are related only to their own implants, expensive and cannot be used as a universal or an open platform4-6. This invention is a device and a method for preparing a knee joint for a prosthesis in a patient undergoing TKA surgery for any knee implant (prosthesis). The device and the method are used in a universal and an open platform fashion for any currently available knee implant, all patient specific implants and any knee implants that could be produced in future. The device is a patient specific instrument, which is based on a method comprising of image based (CT, MRI or computed X-ray) 3-D preoperative planning to design the templates (PSI) that are used to perform the knee surgery for any knee implant in a universal and open platform fashion.