Patient-Specific Bone Graft Shaping for Glenoid Implant Seating
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Solution Overview
Problem
Existing shoulder arthroplasty procedures, such as BIO-RSA, face challenges with standard spacers that do not conform to the unique shape of the glenoid surface, leading to improper seating and early loosening of implants due to excessive reaming or insufficient bone preparation.
Innovation Solution
The development of patient-specific spacers formed from bone graft material, shaped using three-dimensional spatial location information of the patient's joint surface, allowing for customized adaptation to the glenoid surface without extensive reaming, using a bone press to reshape a bone graft blank to match the patient's anatomical needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If standard spacers with flat surfaces are used in BIO-RSA, then the spacer can be manufactured with simple geometry, but the spacer will not seat properly on worn glenoid surfaces and early loosening occurs
Solution Approach 1:
Patient-specific spacers are custom-designed and manufactured before surgery based on preoperative imaging data of the patient's glenoid surface. The spacer geometry is predetermined to match the patient's unique anatomy, allowing proper seating without requiring extensive reaming of the glenoid surface during surgery.
Solution Approach 2:
The spacer is created as a custom copy of the patient's glenoid surface geometry. Using CT scanning and 3D modeling, an accurate digital replica of the glenoid is obtained, and the spacer is designed to conform precisely to this replicated surface, ensuring optimal contact and distribution of forces.
2Ease of manufacture
If excessive reaming is performed to create a flat surface for spacer seating, then the glenoid surface can accommodate standard spacers, but dense subchondral bone is removed and early loosening occurs
Solution Approach 1:
Instead of creating a uniform flat surface through extensive reaming, the patient-specific spacer is designed to accommodate the local variations in the glenoid surface geometry. The spacer's contact surface is customized to match the specific contours and irregularities of the patient's glenoid, allowing proper seating while preserving the existing bone structure.
3Reliability
If patient-specific spacers are custom-formed to match the glenoid surface, then proper seating and bone preservation are achieved, but the manufacturing process becomes more complex
Solution Approach 1:
While each spacer is patient-specific, the manufacturing process utilizes universal technologies such as CT scanning, 3D modeling software, and additive manufacturing. These standardized technologies can be applied across different patients, making the complex customization process more efficient and scalable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables improved implant seating and reduces the risk of early loosening by providing a tailored spacer that conforms to the patient's joint shape, preserving bone integrity and enhancing the longevity of the implant.
Implementation Method 1
The bone contact surface of the bone graft blank is compressed against the contoured surface of the patient specific insert negative. The bone contact surface is reshaped to form a patient specific bone graft.
Data Source
AI summary
A bone press includes a base; a compression plate located opposite to the base; a housing that extends between the base and the compression plate, the housing extending along a longitudinal axis of the bone press; a pressing zone within the housing and between the base and the compression plate along the longitudinal axis of the bone press; and an actuator to provide relative movement between the compression plate and the base to create compression in the pressing zone.