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 surrounding bones and tissue, often requiring large incisions that can cause tissue trauma and increase complications, as existing reamers are not adaptable for small incisions.
Innovation Solution
A reaming instrument with an adjustable profile that includes a rotatable cutting head and radially displaceable cutting elements, allowing the profile to be minimized for insertion through small incisions and expanded for effective bone preparation, utilizing a gear wheel and rack mechanism for radial adjustment.
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 be inserted and used for bone preparation, but tissue trauma increases and healing time is prolonged
Solution Approach 1:
The reamer incorporates radially displaceable cutting elements that can be moved between retracted and extended positions. During insertion, the cutting elements are retracted to minimize the profile, allowing passage through small incisions. Once positioned, the cutting elements are extended to provide full cutting capability for bone preparation.
Solution Approach 2:
The cutting elements are designed to be nested within the reamer body when in the retracted position. The radially displaceable cutting elements can be stored inside the reamer shaft, similar to nested dolls, allowing the reamer to have a compact insertion profile while maintaining full cutting functionality when deployed.
2Object-affected harmful factors
If the reamer profile is minimized for small incision insertion, then tissue trauma is reduced, but the cutting capability is compromised
Solution Approach 1:
The reamer transitions from a static design to a dynamic one where the cutting elements can change position radially. This dynamic capability allows the same instrument to provide both a minimized profile for insertion and full cutting capability for bone preparation, eliminating the need to choose between the two opposing requirements.
Solution Approach 2:
The reamer is segmented into a stationary body and radially displaceable cutting elements. This segmentation allows the cutting elements to be independently positioned - retracted during insertion to minimize trauma, and extended during cutting to provide full adaptability and cutting capability.
3Device complexity
If traditional fixed-profile reamers are used, then the structure is simple, but the instrument cannot be adapted for minimally invasive procedures
Solution Approach 1:
The addition of radially displaceable cutting elements with adjustment mechanisms transforms a simple fixed-profile reamer into an adaptable instrument. The dynamic positioning capability allows the same basic structure to accommodate both minimally invasive procedures with small incisions and traditional procedures with larger incisions.
Solution Approach 2:
The reamer becomes a universal instrument that can perform multiple functions - insertion through small incisions with cutting elements retracted, and bone preparation with cutting elements extended. This multi-functionality is achieved while maintaining relatively simple adjustment mechanisms that can be operated during the surgical procedure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables minimally invasive bone preparation with reduced tissue trauma by allowing the reamer to be inserted through small incisions and expanded for effective cutting, minimizing the need for large incisions and reducing recovery time.
Implementation Method 1
utilizing a gear wheel and rack mechanism for radial adjustment
Data Source
Figure 1
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Figure 4~4A
AI summary
A reaming 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 reamer 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 cutting the bone.