Articular cartilage smoother for arthroscopic surgeries

The goal of the project is to work together and utilize all the strengths of all team members, both technical and not, to produce a functional arthroscopic random orbital shaver that satisfies, if not exceeds, the expectations of our client while simultaneously advancing our familiarity with the engineering design and manufacturing process.

=Problem Definition=

Problem Statement

We were tasked with designing a device to address the underlying issues presented when performing arthroscopic debridement. Current shavers utilize a rotating drum-shaped shaving head that, when pressed against cartilage or bone, can cause ripples, which creates a suboptimal post-surgical result.

Value Proposition

The surgical interventions that are currently used for addressing articular degradation, particularly in the knee, are to perform total joint replacements or simply do nothing at all. Some individuals, however, are too young or simply unfit for a total joint replacement, and for those patients there is a third alternative arthroscopic debridement. Arthroscopic debridement is currently used as a method to shave down damaged articular surfaces (i.e. cartilage and bone) to minimize inflammation and pain. Current shavers utilize a rotating drum-shaped shaving head, that when pressed against cartilage or bone, can cause ripples in those surfaces, which results in a suboptimal post-surgical result. Our team is driven to improve this procedure by creating a novel arthroscopic shaver that can be used to create smoother articular surfaces. Our shaving device will improve the lives of orthopedic surgeons by creating a more ergonomic and functional than current technologies. This will be achieved with design components such as making the handle into a pistol-grip shape instead of the current pencil grip. But, most importantly, our device should result in a post-surgical joint that lasts longer and is more comfortable, improving the quality of life for patients.

Background
Current Technologies

Current shavers utilize a rotating drum-shaped shaving head, that when pressed against cartilage or bone, can cause ripples in those surfaces, which results in a suboptimal post-surgical result.

Cartilage

Cartilage is a tissue that decreases friction, distributes loads and contains stress shielding due to high water content and structural properties. Its structure contains 3 layers of collagen fibers with different orientations parallel in the superficial zone, disorganized throughout the middle and vertical in the deep zone. Unfortunately, cartilage has a poor healing capacity and after normal wear and degradation usually leads to surgical repair.



Deliverables
Objective Statement

Our team is driven to optimize arthroscopic debridement by creating a vibrational arthroscopic smoothing device that creates smoother articular surfaces, which results in a post-surgical joint that provides an improved quality of life for patients.

Specifications and Requirements
-Comfortable and lightweight​

-Shaft diameter of less than 5 mm​

-Biologically compatible materials​

-Autoclavable​

-Compatible with suction and fluid flow​

-Creates smooth articular surface

-Large pistol like handle

-Must be sturdy

-Less than $3000

=Design=

The design that we came up with is a drive shaft (Inner shaft and Outer shaft) with a fixed rectangular head and curved edges to be able to travel smoothly over rough surfaces while operating with a side to side vibrating motion. The smoothing of the articular surfaces is accomplished using a gritted head that functions analogously to sandpaper. The vibration, along with the head’s flat or convex surface, helps mitigate the possibility of ripple formation while still creating a smoother surface on the cartilage and bone. The vibration is created by a vibration motor that is connected to the back of the driveshaft. However, for the handle of our device we used a handle shaped like a pistol, which is more ergonomic and convenient for the surgeon to hold while operating.

Material selection  


 * Outer suction shaft – Aluminum​

-High strength to weight ratio, non-toxic, inexpensive, and sterilizable​

-Common in handles and bodies of surgical instrument​

-Should be coated to reduce corrosion​


 * Inner driveshaft and head – 316L "medical grade" stainless steel​

-Less expensive than titanium​

-Strong, yet able to be gritted through sandblasting or lapping​

-Common in surgical instruments​

-Corrosion resistant in aqueous and saline environments​

CAD Model Design:

Electrical Design:

=Project Learning=

Throughout our project we have gained valuable practical experience following the engineering design process. From our initial brainstorming stage,  to our complete prototype and many iterations in between, we have learned the importance of collaboration, communication, and the impact of technological advancement through engineering. While many current surgical technologies are already very advanced, they can always be improved to ease  surgeons’ lives  and improve patient care and successes.

Future Work

This design has limitless potential within the surgical field with more development. Further testing can be performed on the suction mechanism and other design components. More precise and quantitative data can be collected using more advanced microscopy to characterize the articular surface roughness. There is the potential for designing concave and convex smoothing heads that are detachable and interchangeable.Undergoing further prototype testing, revisions, and design iterations, The device could be professionally manufactured with the selected metals and materials. Long term, our goal would be to perform in vivo trials with inflammation response data, patient pain ratings, and other parameters to provide insight into the improvement of arthroscopic debridement procedures.

=Final Design=  

Assembly includes:​

-Driveshaft / Smoothing Surface (Pink)​

-Outer Shaft (Pink)​

-Fluid Chamber​

-Connector Jacket (Purple)​

-Motor & Clips (Red)​

-Trigger / Springs / Push Button (Green)​

-Circuit Board (Yellow)​

-Battery Compartment (Blue)​

-Charger Placement (Orange)​

-Nuts & Bolts for fastening​

-3D-Printed Encasing Handle

Final Prototype

=Testing=

Our model uses a vibrational sanding technique, so through testing, we determined what size of grit would be appropriate. We used the femoral condyles of chickens as a test subjects. We used 8 different grits of sandpaper on the articular surfaces and observed them under a microscope to see which one gave the smoothest surface. Our final results yielded that 300 - 400 grit sandpaper, which are both on the finer end of the spectrum, would give us the smoothest results.

=Budget and Validation= Our Client gave us a budget of $3000 that we have split up in these parts:

Total Budget: $3000​

Actual Spent: $973

Here is an preview of our validation plan, and below is a link to the full file of our DVP.





=Team Members=

=Additional Documentation=

Project Schedule



Meeting Minutes



Presentations







Client Interview