Angular Bone Milling Tool with Shielded Drive Shaft
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Solution Overview
Problem
Current bone milling systems require large incisions for surgical procedures due to the fixed orientation of the drive shaft, limiting the precision and versatility of bone preparation for prosthetic implants, and posing risks such as bone fracture and soft tissue engagement.
Innovation Solution
A triangular milling system with a shielded drive shaft assembly and constant velocity joint allows for angular orientation of the drive shaft, reducing the incision size by protecting soft tissue and enabling precise cutting of a triangular cavity within a smaller incision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a fixed orientation drive shaft is used in traditional milling systems, then the structure is simple, but the incision size must be large to accommodate the laterally extending input shaft and drill
Solution Approach 1:
The drive shaft is nested within a protective sleeve that extends laterally beyond the frame edge, allowing the input shaft to be positioned without extending beyond the frame. The protective sleeve acts as a containing structure that shields soft tissue while accommodating the drive shaft mechanism inside the smaller frame footprint.
Solution Approach 2:
The invention transitions from a fixed linear orientation to angular orientation capability by introducing a constant velocity joint. This allows the drive shaft to rotate and accommodate input power from various angular directions, effectively adding rotational freedom in another dimension while maintaining a compact frame structure.
2Length of moving object
If the input shaft extends laterally beyond the frame edge, then power transmission is direct, but the incision must be larger than the frame width to avoid soft tissue engagement
Solution Approach 1:
A protective sleeve is introduced as an intermediary component between the drive shaft and the external environment. This sleeve extends laterally beyond the frame edge to shield soft tissue from the rotating drive shaft, while the drive shaft itself remains contained within the frame, eliminating the need for a larger incision.
3Ease of manufacture
If broaching is used for bone preparation, then the procedure is simpler, but there is a risk of bone fracture and deflection by harder bone sections
Solution Approach 1:
The invention replaces the broaching mechanical system (pounding action) with a milling system that uses a rotating cutter with cutting teeth. This substitution eliminates the impact forces that cause bone fracture while maintaining the ability to prepare the bone surface, and the controlled rotational motion prevents deflection by harder bone sections.
4Manufacturing precision
If a standard triangle miller system is used, then precise triangular canal machining is achieved, but the incision must be nine to twelve inches long
Solution Approach 1:
The drive shaft mechanism is nested within the protective sleeve, which is contained within the frame structure. This nested arrangement allows all necessary components to be housed within a compact frame that fits through a smaller incision while maintaining the precision machining capability of the triangular canal cutter.
Solution Approach 2:
The constant velocity joint introduces dynamic angular orientation capability to the previously fixed drive shaft system. This allows the miller to be positioned at various angles relative to the bone, providing surgical versatility while maintaining the precise triangular canal geometry through the cutter's controlled rotational motion.
Data Source
AI summary
A milling system for creating a cavity in a bone includes a drive shaft, a frame for carrying a cutter and a cutter for cutting the cavity. The drive shaft has a proximal end and a distal end forming a portion of a drive joint for coupling the drive shaft to a cutter. The frame includes a frame shaft and a cutter mount, mounting a cutter at a first angle. The mount includes a bearing bracket extending laterally from the frame shaft to a bearing receiving a portion of a cutter and maintains the received cutter oriented at the first angle during rotation. The cutter has a head forming a portion of drive joint for coupling the cutter to a drive shaft. The cutter is received in the mount at the first angle and the drive shaft forms a second angle with the longitudinal axis less than the first angle.