Adjustable Profile Reamer for Minimally Invasive Bone Preparation
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Solution Overview
Problem
Minimally invasive surgical procedures for joint arthroplasty, such as shoulder joint replacements, face challenges in accessing the joint due to the joint's anatomy, often requiring large incisions that can cause tissue trauma and increase complications, as existing reaming instruments are not adaptable to fit through small incisions.
Innovation Solution
Development of a minimally invasive reaming instrument with an adjustable profile, featuring a rotatable cutting head and radially displaceable cutting elements that can be operated to minimize or maximize the cutting head's profile, allowing insertion through small incisions and expansion for bone preparation, utilizing a gear wheel and adjustment mechanism to facilitate radial displacement of cutting elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a large incision is made to accommodate the full profile size of the reamer, then the reamer can access the joint and perform bone preparation, but tissue trauma increases and healing time is prolonged
Solution Approach 1:
The cutting head employs radially displaceable cutting elements that can be moved between retracted and extended positions. When retracted, the profile is minimized for insertion through small incisions; when extended, the full cutting capability is available for bone preparation, thus resolving the contradiction between minimal incision and effective bone access
Solution Approach 2:
The cutting elements are nested within the cutting head structure when retracted, allowing the reamer to pass through small incisions. Upon deployment, the cutting elements extend outward to provide the necessary cutting diameter for bone preparation, effectively nesting the functional cutting surface within a compact insertion profile
2Object-affected harmful factors
If the cutting head profile is minimized for minimally invasive insertion, then tissue trauma is reduced, but the cutting capability is limited
Solution Approach 1:
The cutting elements are designed to be radially displaceable, allowing dynamic adjustment between a retracted state for minimal tissue trauma during insertion and an extended state for effective bone preparation. This dynamic transformation enables the instrument to maintain both minimally invasive characteristics and adequate cutting capability
Solution Approach 2:
The cutting elements are positioned in a retracted state before insertion to minimize tissue trauma, then extended after successful insertion and positioning within the joint. This preliminary retraction allows the instrument to reach the target site through small incisions before deploying the full cutting function
3Productivity
If the reamer has a fixed large profile for bone preparation, then cutting effectiveness is maintained, but the instrument cannot be inserted through small incisions
Solution Approach 1:
The cutting head transforms from a compact configuration during insertion to an expanded configuration during operation. The radially displaceable cutting elements enable this transformation, providing a small insertion profile that can pass through minimal incisions while maintaining the capability to achieve full cutting effectiveness once deployed
Solution Approach 2:
The cutting head is segmented into multiple radially displaceable cutting elements rather than a solid fixed structure. This segmentation allows each element to be independently positioned, enabling the overall profile to be minimized for insertion while maintaining the potential for full cutting diameter when elements are extended
Data Source
AI summary
A planing instrument, in accordance with one embodiment, includes a rotatable cutting head and a cutting face on a distal end of the cutting head. At least one radially displaceable cutting element has a cutting edge projecting in a distal direction from the cutting face. An adjustment element is operable to displace the cutting element toward a fully retracted state, or toward a fully expanded state. In another embodiment, a method of modifying a bone surface includes displacing at least one cutting element on a planing instrument to a fully retracted state, inserting the instrument into a human or animal, operating an adjustment element to displace the cutting element toward an expanded state, and activating the cutting head to begin planing the bone.