Natural Alignment Knee Instruments for Osteoarthritis
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Solution Overview
Problem
Conventional joint replacement surgeries, such as total knee arthroplasty, often rely on standard mechanical alignment methods that may not optimize joint functionality for individual patient anatomy, particularly for patients with osteoarthritis, leading to potential misalignment and suboptimal outcomes.
Innovation Solution
The development of specialized instrumentation and methods that allow for anatomic alignment of orthopedic implants, referencing pre-arthritic joint conditions, including adjustable guides for femoral and tibial resection, and modular components to restore the natural alignment and functionality of the knee joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If standard mechanical alignment methods are used for joint replacement, then the surgical procedure is simplified and can be performed with conventional instrumentation, but the alignment may not optimize joint functionality for individual patient anatomy
Solution Approach 1:
Patient-specific instruments are manufactured before surgery based on preoperative imaging and planning. These instruments incorporate patient-specific anatomical references and alignment parameters, allowing the surgeon to directly transfer the pre-planned optimal alignment to the actual bone resection without requiring intraoperative alignment procedures
Solution Approach 2:
The patient-specific instruments create a physical copy or replica of the patient's unique anatomy and pre-determined alignment parameters. The instruments include custom-cutting guides, alignment jigs, and positioning devices that replicate the optimal alignment configuration calculated from patient-specific data, enabling precise reproduction of the planned alignment during surgery
2Ease of manufacture
If conventional arthroplasty jigs are used to position bone resection instrumentation, then the instrumentation can be positioned and oriented, but accurate implant alignment requiring one- to two-millimeter translational precision and one- to two-degree rotational precision is difficult to achieve
Solution Approach 1:
The optimal resection depth, orientation, and implant position are calculated and determined in advance through preoperative imaging and computerized planning. Patient-specific instruments are manufactured with these pre-determined parameters built in, eliminating the need for complex intraoperative alignment procedures and allowing direct transfer of the precise alignment plan to the actual surgery
Solution Approach 2:
Patient-specific instruments replicate the precise alignment parameters and anatomical references unique to each patient. The instruments include custom-designed cutting guides, positioning jigs, and alignment devices that physically embody the optimal alignment configuration, enabling reproduction of the planned one- to two-millimeter translational precision and one- to two-degree rotational precision
3Adaptability or versatility
If standard surgical techniques align bone preparation to the mechanical axis, then the procedure follows conventional guidelines, but the natural alignment and biomechanics of the knee joint may not be restored
Solution Approach 1:
The patient's natural pre-arthritic alignment and biomechanical parameters are measured and determined through preoperative imaging and analysis. These natural alignment parameters are used to plan the surgery and are incorporated into the design of patient-specific instruments, ensuring the natural alignment is restored rather than imposing a standard mechanical axis alignment
Solution Approach 2:
Patient-specific instruments replicate the patient's unique natural anatomical references and alignment parameters. The instruments include custom guides and positioning devices that physically embody the patient's pre-arthritic alignment configuration, enabling accurate reproduction of the natural alignment during surgery and restoration of the knee's original biomechanics
Data Source
AI summary
A method for aligning an orthopedic implant in a joint replacement includes determining the bone and cartilage deficiency from an undegenerated state caused by wear of a joint. Then a resection of a bone in the joint is made based on the deficiency of bone and cartilage from the undegenerated state and the size of a joint implant so as to locate the joint surface of the implant in the undegenerated cartilage location. The condylar wear from the undegenerated states may be assessed at a distal and posterior location on each of a medial and a lateral femoral condyle. A distal cut is made on the femur at a location adjusting for the condylar wear from the undegenerated state. The distal cut varus-valgus angle is oriented parallel to a plane across the distal femur after adjusting for wear in the distal location on the medial and lateral condyle.