Bone Plate Flap Contouring for Pelvic Fracture Stability

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Solution Overview

Problem

Existing bone plate implants for large surfaces, such as the pelvis and scapula, face challenges in accurately contouring and adjusting the slope, leading to suboptimal fits and potential instability in comminuted fractures, especially in high-impact areas like the quadrilateral surface of the pelvis.

Innovation Solution

A bone plate implant design featuring a frame portion and a flap portion connected via a material interconnection, allowing for adjustable bending and plastic deformation, enabling precise fitting to the bone surface with a pre-bent angle of inclination between 10° and 20°, and formed from a single piece of material like implant-grade stainless steel for enhanced stability and ease of manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If the plate is contoured beyond the bending extent required to touch the bone surface, then pressure on the inside shape is achieved, but the slope adjustment becomes very difficult leading to suboptimal fit along outer edges

Engineering Contradiction:
Improvecontour fit to bone surfaceVSAvoidslope adjustment difficulty
Core Design Contradiction:
ShapeVSEase of operation

Solution Approach 1:

The bone plate is divided into distinct segments: a frame portion and a flap portion, connected by a material interconnection. This segmentation allows independent adjustment of each portion - the frame can be contoured to match the bone surface while the flap can be independently positioned at the required angle, eliminating the difficulty of adjusting slope after excessive contouring.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The material interconnection between the frame and flap portions is designed to be plastically deformable, allowing the flap to be dynamically adjusted to the correct angle during surgery. This dynamic adjustability enables precise slope control without compromising the contour fit achieved by the frame portion.

Inventive Principle:
Principle #15Dynamics

2Ease of manufacture

If a single piece of material is used for the bone plate, then manufacturing simplicity and structural integrity are improved, but adaptability to complex bone surfaces is reduced

Engineering Contradiction:
Improvesingle piece manufacturingVSAvoidfit to complex bone surfaces
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

While manufactured as a single piece, the plate incorporates functional segments (frame and flap portions) connected by a deformable material interconnection. This allows the plate to be adapted to complex bone surfaces through plastic deformation of the interconnection region, maintaining manufacturing simplicity while achieving custom fit.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The material interconnection is designed with specific plastic deformation characteristics that allow it to be permanently shaped during surgery. By changing the physical parameters of the material (through controlled deformation), the plate adapts to complex bone geometries while remaining a single-piece construction.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the flap portion is pre-bent at an angle of 10-20 degrees, then optimal buttressing force is achieved for comminuted fractures, but manufacturing complexity increases

Engineering Contradiction:
Improvebuttressing force for comminuted fracturesVSAvoidpre-bent angle configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The flap portion is pre-bent at the optimal 10-20 degree angle during manufacturing, so that when the plate is installed, the flap is already positioned to provide the correct buttressing force for comminuted fractures. This preliminary action eliminates the need for complex intraoperative angle calculations and positioning.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The pre-bent angle is optimized within the 10-20 degree range to provide the ideal balance between structural support and fracture compression. This parameter optimization ensures reliable buttressing force while the plastic deformability of the material interconnection allows fine-tuning if needed.

Inventive Principle:
Principle #35Parameter changes

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

The design provides improved buttressing and stability for comminuted fractures by allowing precise contouring and adjustable spring force distribution, reducing the need for fasteners in critical areas and enhancing the fit along the bone surface, thereby supporting the bone effectively without repositioning.

Implementation Method 1

The flap portion is partially attached to the outer frame portion via a material interconnection and is bendable with respect to a surface defined by the frame portion

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The flap portion is adjustable relative to the frame-surface by plastically deforming a portion of the material interconnection between the flap portion and the frame portion

Methodology Applied
Scientific EffectPlasticity: Plasticity

Implementation Method 3

The material interconnection of the flap portion to the frame portion comprises a spring constant between 200N/mm and 2400N/mm

Methodology Applied
Scientific EffectSpring force: Spring

Data Source

PatentEP2494934B1Bone plate
Publication Date: 2015.12.16 STRYKER EUROPEAN HOLDINGS I LLC
  • EP2494934B1 patent drawingFigure 1
  • EP2494934B1 patent drawingFigure 2
  • EP2494934B1 patent drawingFigure 3

AI summary

The invention relates to a pelvic or scapular bone plate implant (10) having a planar or curved outer frame portion (11). The frame has a surface which can be aligned with a surface of a bone to which the bone plate is to be implanted. The plate has a flap portion (12), the outer frame portion at least partially surrounds the flap portion such that the bone contacting surface the flap portion is located within the outer boundary of the frame portion. The flap portion is connected with the outer frame portion via a material interconnection (16) which allows the flap to be bent with respect to the frame. A method for implanting such a bone plate implant is also taught.