Radial Cranial Bone Flap Fixation for Dura-Safe Closure
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Solution Overview
Problem
Existing cranial bone flap fixation implants risk unintentional pressure on the dura mater, cause cosmetic issues, and are unsuitable for severe skull curvatures, leading to potential epidural hematomas and unsatisfactory fixation.
Innovation Solution
A cranial bone flap implant with a mechanism that allows radial fixation, using a transverse distance adjustment between sections to apply forces radially, avoiding axial pressure and enabling bone-to-bone contact for improved fixation and regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If axial clamping of plate elements is used to fix the bone flap, then fixation strength is improved, but unintentional pressure on the dura mater occurs leading to epidural hematoma
Solution Approach 1:
The patent inverts the fixation approach by using a rod element that applies radial forces outward from the skull bone toward the bone flap, rather than axial clamping forces. The rod element has a first end for force transmission to the skull bone and a second end for force transmission to the bone flap, with a mechanism that increases the distance between these ends to generate radial fixation forces that avoid dural pressure while maintaining fixation strength.
Solution Approach 2:
The rod element serves as an intermediary component between the skull bone and the bone flap. It transmits forces radially outward through the annular gap, mediating the fixation process without direct axial contact that would compress the dura mater. The rod element works in conjunction with a spreading mechanism to distribute forces safely.
2Stability of the object's composition
If plate elements are placed in the epidural space for fixation, then fixation stability is improved, but cosmetic appearance deteriorates due to visible implants
Solution Approach 1:
The patent extracts the implant components from the epidural space and places them in the extradural space (outside the dura mater). The rod element and plate elements are positioned in the annular gap between the skull bone and the bone flap, removing the cosmetic defect of visible epidural implants while maintaining fixation stability through radial force transmission.
3Ease of manufacture
If standard implant designs are used for fixation, then ease of manufacture is improved, but adaptability to severe skull curvatures deteriorates
Solution Approach 1:
The patent introduces a dynamic spreading mechanism that can adjust the distance between the first and second ends of the rod element. This allows the implant to adapt to varying annular gap dimensions and skull curvatures. The mechanism may include threaded connections, cam mechanisms, or hydraulic systems that enable the rod element to spread radially outward to match the specific geometry of each patient's skull.
Solution Approach 2:
The patent changes the key parameter of the rod element from a fixed length to a variable length that can be adjusted during implantation. By modifying the distance between the first and second ends of the rod element, the implant can accommodate different skull curvatures and annular gap sizes while maintaining radial fixation forces.
Data Source
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AI summary
The invention relates to an implant for fixing a cranial bone flap in a cranial opening, said implant comprising: a longitudinal axis which is aligned along an axial direction of the cranial opening; a transverse axis which is aligned along a radial direction of the cranial opening; a first portion which is designed to transmit force to the bone flap; a second portion which is designed to transmit force to a cranial bone surrounding the cranial opening, the first portion and/or the second portion being designed to be positioned in an annular gap formed between an outer periphery of the bone flap and an inner periphery of the cranial bone; and a mechanism which is operatively connected to the first portion and the second portion and by means of which a transverse distance projected onto the transverse axis can be at least increased between the first portion and the second portion, as a result of which the first portion can be pressed radially inwardly against the bone flap and the second portion can be pressed radially outwardly against the cranial bone.