Spinal Construct Snap-Fit Assembly for Lower Surgical Force
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Solution Overview
Problem
Existing spinal constructs for treating disorders such as scoliosis, kyphosis, and degenerative disc disease often require complex instrumentation and high forces for assembly, which can complicate surgical procedures and increase patient discomfort.
Innovation Solution
A spinal implant system featuring a low-profile spinal construct with a screw receiver that allows for manual, non-instrumented assembly using a snap-fit mechanism, reducing the force required for attachment and enabling assembly with forces as low as 2-50 N, and includes a modular design for flexible alignment and attachment to various bone screws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex instrumentation and high forces are used for assembly of existing spinal constructs, then reliable vertebral stabilization is achieved, but surgical complexity and patient discomfort increase
Solution Approach 1:
The spinal construct components are designed to self-assemble through a snap-fit mechanism where the rod automatically engages with the bone screw head features without requiring external instrumentation. The complementary geometric features (polygonal rod cross-section matching polygonal groove in bone screw head) enable self-alignment and secure attachment through simple manual insertion forces
Solution Approach 2:
Complex mechanical assembly instrumentation and high-force application systems are replaced with a simple snap-fit mechanical engagement system. The connection relies on geometric interlocking and elastic deformation of the rod material rather than complex fastening mechanisms or high-force torque applications
2Strength
If complex instrumentation and high forces are used for assembly of existing spinal constructs, then secure fastener attachment is achieved, but assembly force requirements increase patient discomfort
Solution Approach 1:
The rod is designed with a polygonal cross-section (e.g., hexagonal or octagonal) that complements the corresponding polygonal groove in the bone screw head. This geometric curvature design enables the rod to flex elastically during insertion and snap into place, achieving secure attachment with minimal insertion force while distributing stresses evenly across the engagement surfaces
Solution Approach 2:
The rod material and cross-sectional geometry are designed to undergo controlled elastic deformation during assembly. The rod temporarily changes shape (bends or flexes) to pass through the bone screw head groove, then springs back to its original shape, creating a secure snap-fit connection that maintains strong attachment with minimal assembly force
3Reliability
If traditional spinal construct assembly methods are used, then vertebral stabilization is achieved, but surgical procedure time and complexity increase
Solution Approach 1:
The rod and bone screw head are pre-designed with complementary geometric features (polygonal cross-sections) that ensure automatic alignment and engagement. This preliminary geometric configuration eliminates the need for complex alignment procedures or specialized assembly instrumentation during surgery, allowing rapid secure attachment that reduces surgical procedure time while maintaining reliable vertebral stabilization
Data Source
AI summary
A spinal construct comprises a fastener including a head. A member includes an inner surface defining a cavity configured for disposal of the head and a groove configured for disposal of a band that is engageable with the head to connect the fastener and the member. The member includes a transverse rod. A coupling member is engageable with the inner surface. Implants, systems, instruments and methods are disclosed.