Femoral Surgical Instrument Depth Stop
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Solution Overview
Problem
Current orthopaedic surgical instruments lack precision and efficiency in preparing the distal end of the femur for knee prosthesis implantation during revision knee surgeries, particularly in achieving the correct depth and alignment for optimal prosthetic fit.
Innovation Solution
An orthopaedic surgical instrument assembly comprising a broach with a tapered outer surface and cutting teeth, a handle with mounting brackets, and a depth stop that defines an oblique angle of approximately 85°, allowing for precise depth control and alignment, along with a locking mechanism and spacer plates for adjustable cutting guides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional surgical instruments are used for preparing the femur in revision knee surgery, then the surgical procedure can be completed, but the depth control and alignment precision are insufficient
Solution Approach 1:
The instrument is divided into distinct functional segments: a broach for canal preparation, a handle for manipulation, and a depth stop for precise depth control. Each component can be independently designed and optimized, allowing complex functionality to be achieved through modular assembly rather than a single complex device.
Solution Approach 2:
The depth stop introduces a new dimensional control mechanism by extending perpendicular to the broach axis, creating an oblique reference plane that provides depth measurement in a direction orthogonal to the primary insertion path. This additional dimension enables precise depth control without complicating the primary broaching function.
2Manufacturing precision
If conventional surgical instruments are used for preparing the femur, then the procedure can be performed, but the alignment precision for optimal prosthetic fit is not achieved
Solution Approach 1:
The depth stop is pre-configured with mounting brackets positioned at specific distances from the broach tip, establishing the correct alignment and depth reference before the surgical procedure begins. This preliminary setup eliminates the need for complex intraoperative alignment adjustments, maintaining ease of operation while achieving high precision.
Solution Approach 2:
The depth stop acts as an intermediary reference device between the surgeon's manual manipulation and the bone preparation process. It provides a stable geometric reference that translates the surgeon's control into precise alignment without requiring direct measurement or calculation during the procedure.
3Measurement precision
If a depth stop with oblique angle is added to the instrument assembly, then depth control and alignment precision are improved, but the device complexity increases
Solution Approach 1:
The depth stop is designed to perform multiple functions: it provides depth measurement reference, establishes alignment orientation through its oblique angle, and serves as a mounting platform for the broach assembly. This multi-functionality justifies the added complexity by consolidating several reference functions into a single component rather than requiring multiple separate devices.
Data Source
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AI summary
An orthopaedic surgical instrument assembly (12) includes an instrument handle (14) configured to clamp a broach (20) and femoral stem trial assembly. A depth stop (16) is configured to removably couple to the instrument handle. When the broach and femoral stem trial are advanced into a medullary canal of a patient's femur, a substantially planar proximal surface (144) of the depth stop is configured to engage the distal surface of the femur, determining the depth of the broach in the medullary canal. The proximal surface of the depth stop is parallel to the joint line, defining an oblique angle to the anatomical axis of the femur. The depth stop may be attached to the instrument handle at a number of positions to control the depth of the broach. The assembly may include a spacer plate (198) removably coupled to the depth stop that distalizes the broach in the medullary canal.