Shoulder Arthroplasty End Effector With Offset-Axis Reamer
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Solution Overview
Problem
Traditional reamers in shoulder arthroplasty require a large incision and fixed guide pins, limiting cutting angles and increasing surgical time and recovery due to restricted visibility and single-axis rotation.
Innovation Solution
A reamer configured for use with a robotic arm, featuring a cutting head that rotates on a separate and offset axis, allowing precise adjustment of cutting angles and trajectories without a guide pin, enabling smaller incisions and improved bone preservation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a guide pin is inserted and fixed to the bone surface to guide the reamer, then the reaming operation can be performed, but the cutting angle is restricted and the incision size must be large to accommodate the guide pin and allow visibility
Solution Approach 1:
The patent removes the guide pin from the system entirely. Instead of using a guide pin inserted into the bone to define the cutting axis, the reamer is designed with an self-contained offset axis mechanism where the cutting head rotates on an axis that is laterally offset from the drive shaft axis, eliminating the need for external guide pins and associated large incisions
Solution Approach 2:
The patent introduces a lateral offset dimension between the drive shaft axis and the cutting head rotation axis. This dimensional change allows the cutting head to rotate on a separate axis that is laterally displaced from the drive shaft, enabling cutting at various angles without requiring a guide pin inserted into the bone
2Illumination intensity
If a guide pin is used to guide the reamer, then the reaming can be performed, but the surgeon's visibility of the cutting head is blocked requiring offset viewing positions
Solution Approach 1:
The guide pin is removed from the system, eliminating the obstruction it creates between the surgeon and the cutting head. The offset axis design allows the cutting head to rotate on a separate axis that does not block the surgeon's direct line of sight to the cutting site
Solution Approach 2:
The reamer is segmented into distinct functional components: a drive shaft for power transmission and a cutting head for bone removal, positioned at different locations in space. The cutting head is laterally offset from the drive shaft, allowing the surgeon to view the cutting head directly without the drive shaft or guide pin obstructing the view
3Productivity
If the reamer rotates around a fixed guide pin, then the reaming operation is stable, but the surgical time increases due to inability to adjust cutting angles intraoperatively
Solution Approach 1:
The reamer transitions from a static, guide-pin-dependent system to a dynamic, adjustable system. The cutting head can be positioned and oriented in multiple configurations relative to the drive shaft, allowing intraoperative adjustment of cutting angles and trajectories without removing or repositioning guide pins, thereby reducing surgical time and increasing adaptability
Solution Approach 2:
By introducing the lateral offset between the drive shaft axis and cutting head rotation axis, the system gains an additional degree of freedom. This dimensional change enables the cutting head to access bone surfaces at various angles and trajectories, providing adaptability without requiring guide pin repositioning
4Area of stationary object
If a large incision is made to accommodate the guide pin and allow visibility, then the guide pin can be inserted and the surgery performed, but the incision size is larger than necessary
Solution Approach 1:
The guide pin is extracted from the system, eliminating the need for a large incision to accommodate it. The reamer's self-contained offset axis mechanism requires only a small incision for insertion, and the lateral offset design provides unobstructed visibility through the small incision without requiring additional space for guide pin manipulation
Data Source
AI summary
A robotic surgical system can include an end effector coupled to a robotic arm. A reamer operable to ream bone can be coupled to the end effector (e.g., via a retainer). The reamer can include a primary driveshaft and a cutting head. The primary driveshaft can be rotatable about a first axis of rotation and the cutting head can be rotatable about a second axis of rotation, for example parallel to and offset from the first axis of rotation.