Spacer Augment Molds for Tibial and Femoral Bone Defects
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Solution Overview
Problem
Existing joint replacement surgeries face challenges in managing bone defects and ensuring stable fixation of temporary spacers due to the lack of dedicated instruments, leading to complications such as breakage and instability, particularly in cases of periprosthetic infections.
Innovation Solution
A system comprising symmetrical and asymmetrical femoral and tibial augments, along with cones, is used to correct bone defects and provide stable fixation of temporary spacers, utilizing 3D printing and silicone rubber molds to create customized components that can be autoclaved for sterilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional joint replacement surgery is performed without dedicated instruments for bone defect management, then the surgical procedure can be completed with standard tools, but bone defects cannot be effectively corrected and spacer fixation becomes unstable
Solution Approach 1:
The system segments the spacer into modular components including the main spacer body, augments for bone defect correction, and cones for additional support. This segmentation allows each component to be optimized for its specific function while collectively providing stable fixation and reliable bone defect management.
Solution Approach 2:
The surgical instrument system is designed as a universal platform that can manage various types of bone defects (cavitary, segmental, cortical, medullary) and accommodate different spacer configurations. The system includes multiple augments and cones that can be combined in various ways to address diverse clinical scenarios, making it multi-functional rather than requiring separate specialized tools for each defect type.
2Ease of operation
If preformed mobile spacers are used to maintain joint mobility during infection treatment, then knee flexion can be maintained, but the spacers are prone to breakage and mobilisation under excessive load
Solution Approach 1:
The spacer system employs composite construction combining bone cement material with reinforced internal structures. The cement is cured in molds that create integrated reinforcement patterns, resulting in a composite structure that maintains the mobility benefits of mobile spacers while significantly enhancing structural integrity and resistance to breakage under load.
Solution Approach 2:
The spacer components are pre-formed in molds with integrated reinforcement structures and geometric optimizations before surgery. This preliminary action allows the complex structural design to be perfected in advance, ensuring that when the spacer is implanted, it immediately has the strength and structural integrity needed to withstand physiological loads while maintaining mobility.
3Loss of time
If standard plastic molds are used to create spacers in the operating room, then the spacer can be prepared quickly, but dedicated instruments for correcting deformities and ensuring stable fixation are unavailable
Solution Approach 1:
The system provides a complete suite of dedicated instruments and components (augments, cones, molds) that are prepared and sterilized before surgery. The surgeon receives a pre-assembled system tailored to the patient's specific bone defects, eliminating the need to create these specialized components during the operation. This preliminary preparation maintains quick intraoperative assembly while ensuring all necessary defect correction tools are available.
Solution Approach 2:
The patent introduces an intermediary planning and preparation phase where patient-specific 3D imaging and virtual surgical planning are performed before the operation. This intermediary step allows the surgical system to be customized in advance based on the patient's anatomy and defect characteristics, providing adaptability without consuming operating room time. The virtual models guide the selection and configuration of augments and cones needed for that specific case.
4Stability of the object's composition
If articulated spacers are used to prevent rigidity and osteopenia, then knee flexion greater than 90° can be achieved, but excessive load and movement can cause breakage and mobilisation with reactive synovitis
Solution Approach 1:
The articulated spacer uses composite material construction with reinforced joints and integrated strengthening features. The bone cement is combined with internal reinforcement structures that allow the spacer to flex and articulate while maintaining sufficient strength to withstand physiological loads without breaking or becoming mobile, thus preventing reactive synovitis.
Solution Approach 2:
The spacer design incorporates parameter optimizations including wall thickness variations, reinforcement placement, and geometric features that are specifically tuned to allow controlled articulation while preventing excessive movement. The curing process and material properties are adjusted to achieve the optimal balance between flexibility for knee motion and strength for load-bearing durability.
Data Source
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AI summary
The present invention relates to a system (1) for producing compensatory elements (31, 32, 33, 34, 35) to be used intraoperatively to manage the implantation of a temporary spacer in the presence of segmental and/or cavitary bone defects of the tibia (T) and/or femur (F), said system (1) being characterised in that it comprises at least one cavity (21) configured to mould an asymmetrical tibial augment (31), said cavity (21) having the shape of a half-disk, and/or at least one cavity (22) configured to mould an asymmetrical femoral augment (32), said cavity (22) having the shape of a parallelepiped, and/or at least one cavity (23) configured to mould a symmetrical augment (33), said cavity (23) being U-shaped, and/or at least one cavity (24) configured to mould a tibial cone (34), said cavity (24) having the shape of a truncated cone with an upper base larger than a lower base, and/or at least one cavity (25) configured to mould a femoral cone (35), said cavity (35) having the shape of an elliptical truncated cone with an upper base larger than a lower base. The present invention also relates to a method for producing at least one compensatory element by means of said system.