Minimally Invasive Bone Miller with Angled Cutter
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Solution Overview
Problem
Current bone milling systems for preparing cavities for prosthetic stems require large incisions due to the fixed orientation of the drive shaft, limiting their use in minimally invasive surgeries and increasing the risk of tissue damage.
Innovation Solution
A miller assembly with a cutter and frame that allows the cutter to be mounted at an adjustable angle, enabling rotation and coupling directly to a drill via a handle, allowing for precise bone milling through a smaller incision by accommodating various angles and reducing the need for a large surgical opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a standard triangle miller system is used for bone preparation, then precise machining of the triangular canal is achieved, but a large incision (8-12 inches) is required to accommodate the miller frame and input shaft
Solution Approach 1:
The miller cutter is nested within the miller frame in such a way that the cutter and its mounting mechanism are contained within the footprint of the frame. The input shaft is positioned to rotate within the plane of the frame rather than extending laterally, allowing the entire assembly to fit through a smaller incision while maintaining the ability to machine the triangular canal precisely
Solution Approach 2:
The input shaft is repositioned from a lateral extension beyond the frame to a position where it rotates within the plane of the frame. This dimensional reconfiguration allows the drive mechanism to be accommodated within the incision area rather than requiring lateral clearance, reducing the required incision size while preserving milling precision
2Ease of operation
If the input shaft extends laterally beyond the edge of the miller frame, then the miller can be coupled to a drill, but the incision must be substantially larger than the width of the frame to accommodate the protruding shaft
Solution Approach 1:
The input shaft rotation mechanism is merged with the miller frame structure itself. The shaft rotates within the plane of the frame and is coupled to the cutter through the frame's internal geometry, eliminating the need for lateral extension. The drive connection is integrated into the frame-cutter assembly, allowing drill coupling without requiring additional lateral space beyond the frame width
3Ease of manufacture
If broaching is used for bone preparation, then the process is simpler, but the bone tends to fracture and the cavity is less precise
Solution Approach 1:
The miller system replaces the pounding action of broaching with a controlled rotational cutting mechanism. The miller cutter rotates within the miller frame to precisely machine the triangular canal, eliminating the fracturing associated with broaching while maintaining procedural simplicity through the guided rotational motion and fixed geometric constraints of the frame
Data Source
AI summary
A method of milling a calcar region of the femur. The method includes using a miller assembly including a cutter and a frame. The frame has a longitudinal axis and a cutter mount for mounting the cutter at a first angle with respect to the longitudinal axis of the frame. The cutter mount extends at the first angle from the longitudinal axis of the frame and receives a portion of the cutter and maintain the received cutter oriented at the first angle during rotation. The frame includes a handle that forms a portion of a drive joint for coupling the frame to a drill. The handle is coupled to the drill and the miller assembly is inserted into the femur such that the cutter is located in the calcar region. The drill is then operated, causing the cutter to rotate and mill bone in the calcar region.