Minimally Invasive Bone Nailing Instrument Set with Segmented Sleeves
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Solution Overview
Problem
Current minimally invasive bone nailing techniques lack effective solutions for protecting soft tissue, preventing contamination, precisely defining the nail inlet point, and ensuring accurate milling direction, especially for large calibre medullary pins which require structuring of the medullary space.
Innovation Solution
An instrument set comprising a base sleeve, a rigid guide wire, a dilation sleeve with a tapering end section, and a working sleeve with a stop, allowing for precise positioning and protection of soft tissue, controlled milling direction, and secure fixation within the bone, using a combination of guide wires, dilation sleeves, and working sleeves to minimize tissue damage and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional curved plate or sleeve tissue protection instruments are used, then soft tissue protection is provided, but extracted material distributes into soft tissue parts or knee joint causing contamination and disruptive ossification
Solution Approach 1:
The protection instrument is divided into multiple segments: a base sleeve that remains fixed in the bone, and an extensible working sleeve that can be extended and retracted. This segmentation allows the working sleeve to contain extracted material during milling operations while the base sleeve maintains the access channel, preventing material distribution into surrounding soft tissue.
Solution Approach 2:
The working sleeve acts as an intermediary containment structure between the milling cutters and the surrounding soft tissue. It captures extracted bone material during the milling process and provides a controlled pathway for material removal, preventing contamination of adjacent soft tissue structures.
2Manufacturing precision
If multiple successive milling processes are used for hard diaphyseal bone, then the bone segment remote from entrance is milled, but correction losses occur due to unfavourable cutting angles in the bone segment close to entrance
Solution Approach 1:
A guide wire is inserted beforehand to define the precise desired milling direction and nail trajectory through the bone. The base sleeve is then positioned along this guide wire, ensuring that all subsequent milling operations follow the pre-determined optimal path, eliminating correction losses and ensuring accurate nail placement.
Solution Approach 2:
The guide wire provides continuous directional feedback during the milling process. By referencing the guide wire position, the milling cutters can maintain the correct trajectory even when passing through the bone segment close to the entrance, allowing for precise multi-step milling without losing correction accuracy.
3Object-affected harmful factors
If small calibre medullary pins are used, then minimum tissue damage is achieved, but they are not suitable for secondary corrective measures requiring large calibre pins
Solution Approach 1:
The protection instrument system is designed to be dynamic and adaptable. The working sleeve can be extended to accommodate large calibre medullary pins when needed for corrective measures, and the base sleeve can be repositioned along the guide wire to optimize access angles. This dynamic configuration allows the same system to handle both small and large calibre pins with minimal tissue damage.
Data Source
AI summary
An instrument set for minimally invasive preparation for a bone nailing comprises at least one base sleeve (10) which has a selected axial length with a drive-in end and a tool working end (12) and an inner diameter selected for holding working sleeves (60) or a nail, in particular a medullary pin. Further, the instrument set comprises at least one substantially rigid guide wire (20) which has a selected diameter and a fixing tip (21) at one end, at least one dilation sleeve (30) which has an outer diameter adapted to the inner diameter of the base sleeve (10) for guided displacement therein, an end section (31) tapering away therefrom with an outlet opening (32) for the guided longitudinal displacement of the guide wire (20) through this, and a length which is greater than that of the base sleeve (10), and at least one working sleeve (60) which has an outer diameter adapted to the inner diameter of the base sleeve (10) or next largest working sleeve for guided displacement therein, a length which is greater than that of the base sleeve (10), an inner diameter adapted for guidance of a bore or cutter (90) or a nail to be inserted, and a stop (61) at its one end for working with the tool working end (12) of the base sleeve (10).