Anyone that cares to read my blogs knows I am no fan of microprocessor prosthetic components. Although, I do think it is a good idea to at least try various components in order to see what they may or may not have to offer.
Yesterday I had the opportunity to trial the Biom T2 foot. I have been seeking a trial of the foot for about a year now but the company had some reservations fitting an Osseo patient. They had some concerns given the fact the foot is powered. Ossur had the same concerns when we first discussed the possibility of trialing their Power Knee; although my surgeon cleared the use of such a device after a year post op. The fact that an Osseo patient in the Netherlands recently trialed the foot, gave BIONX a level of reassurance things would be fine. My buddy Jason who is a sales rep for the company arranged for the trial here in Vegas and brought along two prosthetists who also work for the company in order to set things up and film the trial.
The BiOM T2 was designed by Hugh Herr of MIT, who is a bilateral Bk. I find it a bit ironic how Dr Herr has developed the most advanced foot on the market today, yet still utilizes 500 year old socket technology. Although not everyone who wears a socket experiences significant issues, so Osseo wouldn’t make any sense for someone like him. The foot was designed to emulate missing muscles and tendons, allowing an amputee to be propelled forward at toe off. They call it Bionic Propulsion and report patients will be able to do the following.
• Walk with the Gait of a non Amputee
• Walk with the same energy as a non Amputee
• Walk with a natural self-selected walking speed
• Navigate uneven terrain with less effort and greater speed
• Reduce Musculoskeletal stress
The foot is powered and therefore has a fairly large battery on the backside of the unit. It weighs 5.1 lbs with the foot shell and battery, which is the approximate weight of an anatomical ankle/foot for a 200lb person. Battery life for normal walking environments is 4 to 6 hours. The device is intended for both Ak and Bk applications and targets amputees with low to moderate activity levels and has a three year warranty. The ankle is water resistant but not water proof and offers the user a range of 0°–10° Dorsiflixion and 24°of Plantarflexion.
I met with the BIONX team at the Palms Towers here in Vegas. The foot was set up as a cat 6 due to my weight and a non adjustable coupler in between the knee and ankle was utilized for height. The overall set up was a bit short but that didn’t interfere with the trial all that much; except for the fact that I walked with a bit of a dropped right shoulder. It kind of looks odd on video though.
My initial gait was done without a battery installed so I could get the feel for the increased ankle movement. When I sat down the toe of the foot dropped to the ground like the Kinterra does but with a greater degree of motion. Without the battery installed it actually felt a lot like the Kinterra. The ankle movement was a little off and the heel was a bit too soft; which had an effect on the overall motion when stepping through the foot. I could literally feel two distinct movements going on but after installing a heel wedge, the whole thing smoothed out nicely.
After the battery was installed I was impressed at how the whole setup felt. The foot sat square on the ground and I really liked the increase in weight. It actually felt like I was wearing a real leg vs something foreign due to things being so light. I never bought into the whole lighter is better argument that has taken over the modern prosthetic world. As I have been an amputee for just over 30 years now and for 14 of those years I wore a wooden leg; which felt and looked like a real leg. Fabrication of this type of leg is definitely a diminished art. After going to a liner and carbon fiber setup, I lost that feeling and it has bothered me ever since. After the trial I was even thinking of adding weight to the inside of my foot shell to try and mimic that feeling in the foot I am using currently.
When I began to walk on the powered up unit, Brian was busy adjusting the settings on a tablet via Bluetooth; which had a direct effect on how much power I was getting at toe off. At one point it was so much that if felt like I was springing off the toe unnaturally. Although once he dialed it in, the foot began to behave in a more natural motion. There was a distinct power increase at toe off; which helped propel me forward effortlessly and fluidly. At one point during the initial gait setup I immediately felt a level of strain in my front thigh muscle. I asked Brian, did you just make a change to the setting? He responded with a grin, I cut the power. What he did was significant because before he cut the power I literally felt nothing in my thigh muscle and my gait was effortless. When the power cut off, I was working more and took immediate notice of it.
One thing I noticed off the bat was noise. After taking a step the foot returns to a neutral position and it has an audible clunk when it does. As an Ossseo patient I can feel every nuance of a component and that clunk was a bit annoying. It actually felt like when a component is coming loose or failing. I had a similar sound and feeling with the first Centri Torsion Adapter I got a hold of; which ended up being defective. Indoors it was fairly loud as well. Although once we moved outdoors, it faded; although the constant clunk remained.
The next step was to put the foot through some ramp testing and the parking garage offered the perfect environment for that; since they are fairly steep and pretty long. As we walked through the lobby of the hotel to get outside, I walked through the doorway and immediately stopped. There was a noticeable hump at the door as well as a textural and angle difference at that point. I walked right through it not even thinking and noticed how easy and fluid my gait felt. It was enough for me to go back and try it again; just to see what was happening. The second time around the same thing occurred and it felt great; with smooth ankle and knee movement through it all. It was a pretty nice feeling actually.
My first time going up and down the ramp was a bit awkward. I had to focus a little on engaging the toe while going up but when I did the foot propelled me up the ramp fairly easily. I could definitely feel the power assisting me and felt less fatigue overall. The first time I went down the knee wasn’t bending but at that point I was trying to control the bend rather than trusting in the components. Once I did that the knee and foot worked perfectly together and I was able to ride both down the slope pretty easily. One thing stood out though. Normally when I take a slope my sound side experiences an abrupt foot slap when landing due to the injury I have and for which I am supposed to wear a rigid AFO. The steeper the ramp the harder the landing. Although due to the amount of plantarflexion in the BiOM and how smoothly it worked with the VGK; the amount of foot slap was minimal and made it pretty easy to walk down the ramp. I walked up and down that ramp until I was dripping with sweat but I have to say; I wasn’t beat up afterwards.
Once we were finished up, we returned to the room and Brian put my Reflex Rotate back on. Now this is a foot I really like wearing. So nothing has changed there but there is a distinct difference between the two regarding weight and I could feel that immediately. At that point my leg felt a bit foreign from the lack of weight and my alignment was off; which had the foot feeling like there were two distinct movements while rolling through. Once Brian adjusted the foot that movement smoothed out and things returned to the point where it began to perform just the way I like it; with very smooth rollover, no sponge at heel strike, no pop at toe off and enough rotation and shock absorption to make the whole experience extremely comfortable. It’s simply a great foot for my set up.
Unfortunately BIONX doesn’t allow trials outside of a clinical setting, as the unit is pretty expensive to be taking home for a few days. As a result I wasn’t able to put this particular unit through the trusty drunk test but I was able to at least take it outside and get a good feel for the device. It was also interesting to use the foot in conjunction with the VGK. As the VGK is known for offering microprocessor features without having to be tethered to a wall socket, yet here it was working very well with a microprocessor component. Just reflects the fact that one can use any foot with this particular knee.
Overall my experience on the BiOM T2 was good. It offers some pretty nice features that enabled me to walk smoothly and effortlessly on various terrains. The noise and clunk is something that would end up annoying me personally, as the implant provides no forgiveness with such matters. Unlike a socket which has a level of soft tissue buffering, an OI implant is a direct connection to the bone and I literally feel everything. That alone would make the foot not such a great fit for me personally.
I see this foot doing very well in environments where there is a lot of walking; as the powered assist at toe off would be helpful in reducing fatigue. No component is perfect for every situation but if one can afford a foot like this and don’t mind microprocessor technology; than it would be something to consider at least trialing. It is a heavy foot at 5.1 lbs but like I said earlier; I prefer components that mimic a real leg anyway and the benefits of power assist is a really nice feature to have. Personally I would like to see the battery made into a long thin unit that could be strapped to the side of the knee or the outside of a socket for Bk applications and tethered to the ankle, rather than the current bulky unit that is directly behind the lower calf area. The ankle itself isn’t really bulky and a design change like that would allow one to utilize the custom covers that are so popular these days.