Hip Stem Removal Using Drilled Channels and Cutting Wire
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Solution Overview
Problem
Removing a well-fixed hip stem from a femur without damaging or removing excessive bone is challenging, particularly due to the invasive nature of existing methods like extended trochanteric osteotomy, which require significant bone removal and result in prolonged recovery times and increased infection risk.
Innovation Solution
A method involving drilling a channel and hole through the bone adjacent to the prosthetic hip stem, using a targeting guide and cutting wire to intersect and cut the interface between the stem and bone, with the aid of a bone protector pin to minimize bone damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extended trochanteric osteotomy is used to extract a well-fixed hip stem, then the stem can be removed, but extensive bone is cut away requiring prolonged recovery and increasing infection risk
Solution Approach 1:
The cutting wire is passed through multiple drilled channels in the bone, creating segmented cutting paths that collectively form a complete circumferential cut around the hip stem. This allows the stem to be separated into segments for removal without requiring a single large osteotomy window, thereby minimizing bone loss while achieving reliable stem extraction
Solution Approach 2:
Drilled channels serve as intermediaries to guide the cutting wire through the bone to the stem interface. These channels provide a controlled pathway for the wire, enabling precise cutting at the stem-bone interface without requiring extensive bone removal, thus reducing infection risk and bone loss while maintaining effective stem removal
2Ease of operation
If extended trochanteric osteotomy is performed, then access to the hip stem is achieved, but extensive recovery time is required
Solution Approach 1:
Channels are drilled through the bone prior to inserting the cutting wire, preparing the pathway in advance. This preliminary action allows the cutting wire to be easily inserted and advanced to the stem interface without requiring extensive bone removal during the actual extraction procedure, reducing surgical time and promoting faster recovery
Solution Approach 2:
The cutting path is divided into multiple segments corresponding to different drilled channels. This segmentation allows the procedure to be performed through minimally invasive approaches rather than requiring a single large osteotomy, thereby reducing surgical trauma and accelerating patient recovery while maintaining adequate access to the stem
3Reliability
If multiple instruments are used for stem removal, then the well-fixed stem can be extracted, but device complexity increases
Solution Approach 1:
The cutting wire serves multiple functions: it cuts through bone in the drilled channels, cuts through the bone-cement interface, and cuts through the bone-stem interface. This multi-functionality eliminates the need for multiple specialized instruments, reducing device complexity while maintaining effective extraction of well-fixed stems through a standardized approach
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
This approach allows for the removal of a well-fixed hip stem with reduced bone loss and trauma, minimizing recovery time and infection risk, while providing a less invasive surgical method.
Implementation Method 1
cutting an interface between the prosthetic hip stem and the bone with the cutting wire
Data Source
AI summary
A method for removing a hip stem from bone comprises drilling a channel through the bone adjacent to the hip stem from a proximal end to a distal end thereof, the channel defining a longitudinal first axis. The method further comprises drilling a hole along a second axis through the bone adjacent to a distal end of the hip stem such that the channel and the hole intersect. The method additionally comprises inserting a first end of a cutting wire through the channel and the hole and cutting an interface between the hip stem and the bone with the cutting wire.