Development of Bone Cutter
Bone Decorticator for use in Ankle Arthrodesis
Team: Erica Shulsen, Jessica Tobler, Jocelynn Burton, Austin Taylor, and Will Pendleton
Introduction
Osteoarthritis affects 3.4% of the general population and is associated with age, obesity, genetics, and female sex. Different techniques exist to treat osteoarthritis, such as autographing, total joint replacement, and joint fusion.
Arthrodesis is the fusion of joints with the use of a bone cutter. While there are devices on the market today that can decorticate joints (remove the subchondral bone layer), there is a lack of a device that can also harvest bone for autographs. With OsteoCentric Technologies, we are designing a device that can fit in a small hole, create a larger void, and can harvest bone.
SImmetry Decorticator
Arthroscopy Shaver Blades
Bones of the ankle joint.
Our team’s current BladeX Mini instrument design.
OsteoCentric’s original BladeX decortication instrument.
Essential feature: blade deploys perpendicular to the shaft.
Preliminary Research
Our design objectives: Device withstands normal surgical loadings. Device is sterilizable. Device enters through a 6 mm hole and cuts a 15 mm diameter void.
Benchmarking
- SImmetry Decorticator incrementally deploys a cutting blade perpendicular to the shaft of the instrument but does not harvest bone.
- Arthroscopy Shaver Blades require more invasion in the body and differs in the blade adjustment method.
- OsteoCentric's precursor device is the BladeX. Our project goal is to shrink the BladeX to fit an ankle osteotomy procedure rather than a hip osteotomy.
Designing the Perfect Handle
Version 1: Okay height, but too clunky and awkward to hold.
Version 2: Better height, has smooth, comfortable profile, but is just too wide.
Version 3: Same height as Version 2, comfortable and easy to hold. Additional grooves make it easier to hold and twist. Deep channels prevent it from rolling.
Methods
Our team began by analyzing the current BladeX mechanism to understand how it works and its essential features. We decided what features to keep and scaled the rest of the model around them. For example, the height of the bottom knob is the same as the original.
In addition, we calculated expected torque and stresses that the device will experience, and adjusted parts so that it will not break in surgery.
Finally, we worked to create a handle that would provide the most comfort and control while effectively cutting and harvesting bone in a small area inside the body.
Conclusion
Through CAD design, important safety analyses, and several 3D-printed prototype iterations, our team has proven that the original BladeX can be safely and successfully scaled down to a size appropriate for decorticating small joints in the body.
Future Work
- Now, with a complete prototype BladeX Mini developed, the team will utilize our tolerance analysis to create mechanical drawings of each part, which will be fabricated in OsteoCentric's machine shop.
- Then, testing will be done to evaluate device performance, and any necessary design adjustments will be made.