Osteosynthesis Screw Radial Compression Reduction

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Solution Overview

Problem

Conventional osteosynthesis screws, both compressive and non-compressive, face issues with high screw-tightening torque leading to radial compression forces that can cause bone fractures and lines of split, particularly due to their conical shape, which increases the risk of bone damage during stabilization procedures.

Innovation Solution

The development of an osteosynthesis screw with a conical longitudinal section and circular notches in the proximal portion to reduce radial pressure during screw tightening, maintaining mechanical strength and stability while preventing bone damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a conical profile is used for the screw head, then screw-tightening torque increases and control of penetration is improved, but radial compression force increases causing bone cracks and lines of split

Engineering Contradiction:

Improvecontrol of screw penetrationVSAvoidradial compression force causing bone damage

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The screw head features localized notches cut into its conical profile, creating zones of reduced material density specifically at the interfaces with bone tissue. This local modification reduces radial compression forces at critical contact points while preserving the overall conical shape for torque control during insertion.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If material is removed to reduce radial compression, then bone damage is prevented, but screw mechanical strength is weakened

Engineering Contradiction:

Improveradial compression on boneVSAvoidscrew mechanical strength

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The screw head incorporates a porous or lattice-like internal structure within the notched regions, providing both weight reduction and stress distribution benefits. This porous architecture maintains adequate mechanical strength while significantly reducing the radial compression force transmitted to surrounding bone tissue.

Inventive Principle:

Principle #31Porous materials

3Object-affected harmful factors

If a cylindrical profile is used, then radial compression is reduced, but screw-tightening torque control and penetration control become more difficult

Engineering Contradiction:

Improveradial compression forceVSAvoidpenetration control during tightening

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The screw combines a primarily cylindrical profile with localized conical features or notches at the head periphery. This hybrid approach maintains the cylindrical shape for reduced radial compression while adding localized geometric variations that provide torque control during insertion, balancing both requirements.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10299844B2Osteosynthesis screw with reduced radial compression

Publication Date: 2019.05.28 CONMED CORP

AI summary

The invention concerns an osteosynthesis screw (1) formed from a core (2) externally provided with a helical thread (3), said screw comprising a distal penetration portion and a proximal portion forming the head of the screw (6) and having a conical longitudinal section characterized in that the proximal portion comprises annular notches which are formed in the thickness of the core (2) and in the gaps between the threads of said proximal portion in such a way as to reduce the radial pressure during screwing.—Surgical device.