Last November, while discussing my second below-knee amputation, I briefly mentioned changing my prosthetic suspension system and promised a full review sometime in the future. As you probably expected, life got in the way and I found myself covering other topics first.
I’ll cover the basics of prosthetic suspension before diving in, but feel free to skip ahead if you’re already familiar.
A Quick Introduction to Prosthetic Suspension
Like most new amputees, my first leg used a shuttle lock. Systems of this type consist of a single, ridged pin that inserts into a lock at the distal end of your socket and prevents your residual limb from slipping out unless the lock is disengaged. My experience was that this design also required a very tight fitting socket to reach an acceptable level of proprioception (which ended up causing circulation issues).
While I think this system is useful for learning if a patient can tolerate wearing a prosthesis, I found it lacking during as my activity level increased. During athletic pursuits (like cycling or hiking), I required additional socks, and occasionally even needed to doff and clean the liner if I wanted my leg to remain solidly attached.
Throughout early-to-mid 2019, my socket was remodeled several times before ultimately being replaced, as it limited my ability to exercise; one of the primary goals for pursuing amputation. Shortly after I acquired my trike, I discovered a performance plateau where I would gain strength and stamina, which would in turn cause my residual limb to become irritated while I tried to deliver ever-increasing amounts of power to the cranks.
Adding a suspension sleeve helped alleviate some of the discomfort. Still, as summer came to a close, with the real possibility of becoming a bilateral amputee looming on the horizon, I became determined to find a functional alternative.
Suction was on my list of solutions to investigate, but I also knew from a summer of cycling that the volume of my residual limb fluctuated wildly, especially as I shifted from cycling, to hiking, and walking throughout the day. Ideally, I could effortlessly transfer from one activity to another, without significant thought, as I’d done before my injury. Elevated vacuum suspension, where my soft tissue is pulled to the socket walls by a built-in vacuum pump, was the only solution that promised this level of function.
Choosing a Vacuum Solution
When deciding to change my suspension type, my first lesson was in the different types of vacuum use in prosthetics. Some pumps are mechanical, and assist with vacating air in the socket while a user is walking (sometimes referred to as Vacuum Assisted Socket Systems, or VASS). Others are electronic, powered by an internal rechargable battery, and can maintain a consistent level of pressure regardless of activity.
I opted for the latter, which left me with two main contenders: Ohio WillowWood’s LimbLogic pump, and a device called a SmartPuck; built by 5280 Prosthetics, a product development firm attached to the Adaptec Prosthetics clinic in nearby Littleton, Colorado. Both offered the ability to adjust vacuum level without reaching for the pump, but WillowWood’s solution required a key-fob for each pump while the SmartPuck could be controlled via my smartphone.
Investing in the SmartPuck System
Around the same time I scheduled my second below-knee amputation surgery I also decided to commit to the SmartPuck ecosystem. This was largely because any other solution meant two key-fobs, one to manage each pump. I expect my level of activity to increase as a bilateral amputee, and requiring myself to carry more gear, regardless of total weight, doesn’t help achieve that goal.
In short, the vacuum pump itself is excellent. While I don’t have other vacuum systems to compare against, it seems incredibly responsive and activates anytime the vacuum level in my socket drops. Proprioception is second-to-none when compared with other systems that I’ve worn, and I’ve even remarked to my prosthetist that it’s now possible to feel and locate small rocks and other debris under my foot better than I could in years; an adaptive outdoorsman’s dream.
Unfortunately, not everything is as advertised. As of this writing, the SmartPuck application for Android hasn’t been updated since what I believe was its initial release, more than two years ago. When I began testing the pump and accompanying application on Android 9, acquiring a Bluetooth connection between my phone and the pump was frustrating at best. I don’t have an Apple device handy to test myself, but reviews on the iOS App Store indicate that connectivity is needlessly difficult on iDevices as well.
My Pixel 2’s recent upgrade to Android 10 broke connectivity entirely, and for the past several weeks, my vacuum level has been stuck at walking levels, even though I’m currently using a wheelchair.
I’ve brought these issues to the company’s attention and while they’ve been outwardly receptive, I’m not aware of work going on to resolve the user experience concerns. I wish that I had a timeline to share, because it would make recommending the SmartPuck to all of you a much easier proposal. However, I am discussing solutions to my bug reports with the team (since the problems they have are ones I have experience resolving), and hope to have more I can share soon.
In my opinion, the SmartPuck device holds so much potential for amputees in 2020 and beyond. After all, the 5280 Prosthetics website promises “the most advanced prosthetic socket in the world”, a goal I feel we’re on the way to achieving but haven’t reached yet. Additionally, while the app-based interface for a system such as the SmartPuck is preferable, buying into that model requires keeping the application up to date or the product as a whole fails to work as advertised.
Hints on the SmartPuck website suggest that step counting, distance traveled, calories burned, and even socket alignment tools are goals for the application, currently under a “coming soon” banner.
I chose to enter the ecosystem as an amputee technologist becuse I’d like to see this potential realized. Still, I have to admit the my experience as a user has been subpar, especially in these past few weeks. I’m hoping to find opportunities to partner and enhance the lives of amputees because this technology is so compelling.
If you’re prepared to be a trailblazer, I’d welcome the company. That said, unless you have a dedicated controller (like an old iPhone or Android device) that can be locked to a known good version of operating system and SmartPuck application, I’d say hold off for the time being. While the potential of a true “smart socket” exists, it has yet to be fully realized.