Week 10: Exogen 4000 - Ultrasound Therapy

The vets at VOSM got back to Dr. Rider regarding the 8-week radiographs and suggested that because the bone healing is so painstakingly slow, that we try ultrasound therapy. Dr. Canapp suggested that we buy an Exogen 4000 Ultrasound Bone Healing System made by Smith & Nephew. This system is actually intended for human use and has been proven with clinical FDA studies to accelerate bone healing. I had a lot of trouble finding information online so this will be a fairly thorough post as I would like to "nerd out" and share my hours of research to help other dog owners.

Taj modeling with his new Exogen system

First off - Exogen was intended for human use. This means that you will NOT be able to buy a new Exogen system - you can only purchase them used. This means that you will have to go scouting on Ebay, Craigslist, or other creative avenues to track one down. New Exogen systems cost around $4,500 for humans. Typically insurance companies will cover most of that cost so new human patients likely pay anywhere from $200 - $900 for an Exogen system. On the "used" market, you will see the systems run anywhere from $100 - $500.

I will get into the science later in the post, but the system emits ultrasound waves (you cannot hear, feel, or see ultra-sound waves) within a range of about 2.5-3 cubic centimeters from where you place the transducer. This means, you MUST get the transducer right over the area that needs healing although with skinny dog legs - you have some leeway. One treatment on the system lasts for 20 minutes and you usually need to do one treatment a day. Exogen units are guaranteed for 150 treatments; however, I called the sales reps and they said typically the systems are usually good for 220 uses. After that their lithium battery can die and they will not adequately power up any more. The lithium battery is typically guaranteed up for 1-year; therefore, the newer the unit the better. The batteries can only be replaced by Smith & Nephew and they will only replace the battery if you are the prescribed owner of the unit. That means if the unit is for your dog - you are out of luck if the battery dies!

For example, this unit has 29 uses logged.

There are several things that you must be aware of when seeking to purchase an Exogen system.

1. Make sure the unit powers up before purchasing. Ask the seller to send you a photo that shows the full and partial uses left on the system. When you turn the system on it will flash how many full uses (i.e. full 20 minute uses) it has on it (a number flashes on the screen plus the ! symbol in a triangle - see above). Then it will flash a second screen that shows the number of partial uses (i.e. uses for less than 20 minutes). Finally it will flash a screen that starts the 20-minute treatment count down. If the unit does not perceive connectivity (i.e. placed on the skin with conductive gel), it will beep for 30 seconds then automatically shut off. If it does perceive connection for conductivity, it will commence the 20-minute treatment session. During treatment, the screen will count down (in seconds from 20:00) for the duration of the treatment while displaying a (((( symbol that means it is conducting properly. 

2. Ask the seller to send you a photo of the back of the unit which displays the serial number. This is very important! The first four digits of the serial number tell you the month/date the unit was manufactured. You want a unit that is less than a year old if possible to ensure that the battery will work for the duration of your dog's treatment. If the unit is older than 1-year, there is no guarantee that it will work (especially if it is 06, 07, 08, or even 09 model). 

3. The serial number is also important because the FDA recalled many Exogen 4000 units from 2008 and 2009. There were problems with the transduce that reduced ultrasound output. Make sure that the unit you are purchasing is not on this FDA Recall List.  

3. Realize the risk of your purchase. There is no guarantee that despite all these things the unit works. The Exogen does not buzz, vibrate, make noise, etc. If the screen displays what it should - it is very likely the unit is working. But if the previous owner mishandled it (like pulled the transducer wire system) it could possibly not work. I did a LOT of searching on Ebay and Craigslist (about a week) before buying my unit. I was comfortable with Ebay buyer I got it from and all the info he sent to me. Taj needs 60 treatments so I was comfortable with the unit having 20-something uses on it and it was manufactured in 2010. I ended up paying almost $300 for my unit (ouch!!! but that was the price to pay for a newer unit that I am confident will last all 60 treatments). Although the transducer does not vibrate I notice that I can almost feel an energetic microscopic "buzz" from it when holding it for 20 minutes to give Taj a treatment.

4. I would recommend buying from Ebay rather than Craigslist. I believe both Ebay and Paypal offer some guarantee when making purchases. A good seller will also offer at least a 1-week money-back guarantee that the unit powers up when you receive it and indeed has the number of uses displayed as advertised.

Also check out this guide - it's super helpful!

This is the Exogen ultrasound coupling gel needed to conduct the ultrasound waves from the device into the leg. If you run out of gel, mineral oil can be substituted.

The Exogen system contains the Exogen unit (white), the connective cord (gray),
the transducer (black circle), two bottles of conductive gel, wrist band attachment,
instructions, and a carrying case.

Conducting a treatment is easy! You just put some gel on the transducer and then hold it over the area of the break. I like to hold it on with my hand - as I find that easier than trying to rig up the strap (made for humans) around the leg. I keep a gentle firm pressure on it - but do not push hard. If at any time you lose connectivity the unit will beep and you have a 30s "grace period" to get the conductivity back of the unit will shut down. Taj usually sleeps through his treatments. Fine hair on the leg is ok - the vet said the machine should be able to conduct through it - more dense hair - you might have to trim or clip (but NOT shave)! The gel is actually very easy to clean off, and after the session you can just use a paper towel to wipe down the transducer and the leg.

2.38 minutes left of treatment! Look closely to see the ((( sign that indicates the unit is working!

Taj typically naps during treatment. I think he just assumes now
his mom is slightly insane for all the things I do with him!

Applying the transducer directly over the worst part of the radial break. You can strap it
on with the wrist band, but I find holding it snug (but not hard) over the break site is easier. 

So does it work? This page explains how the exogen system works. My science background sometimes makes me a skeptic, but yes I honestly believe this works - quite well - both from the research studies I've looked at as well as anecdotal experience. After just 10 treatments, the leg seems "harder" under the break (e.g. I can now feel the callus). There is now even callus extending far out to that farthest radial bone that was significantly protruding. Taj is using the leg more, trying to bounce around more, and putting a bit more weight on the leg - he's even play bowing to Rumi!

So how does it work scientifically? Prepare for a total dork-out moment.

Well if you read the Nephew and Smith website - they are all about "up-regulation." Now what the heck does that mean? ;) Luckily, I can finally put my undergrad degree in genetics to some good use. "Up-regulation" is a really generic term that honestly doesn't tell you too much! It basically means that the cells in your body are increasing the quantity of different cellular components - like proteins - that help you build RNA (which is related to DNA) that eventually help build cartilage and bone cells. You are increasing gene expression and protein synthesis - e.g. you are making more of the building blocks that will eventually create bone.

The Exogen unit creates ultrasound waves (mechanical pressure waves). These waves are created by synthetic crystals that vibrate at a particular frequency because of their geometries. Now I don't mean vibrate in a "new age" way, I mean they vibrate because you are pulsing electric current through them. The vibration creates sound waves - ultrasound waves - that can penetrate skin and tissue - neat huh?

These ultrasound waves travel through the gel through the skin and into the soft tissue in the leg at the fracture site. These waves then alert the cell receptors called "integrins" that "Hey there is a problem here!" and that "you need to speed up the up-regulation!" So this process attracts more integrins to be "on alert" and they start to cluster in groups together. When integrins start to cluster together, this signals to the cell that "we need more resources/support" so the molecules that are responsible for gene expression head into the nucleus (this is like the "brain factory" of the cell) and they start making more proteins (i.e. building blocks for the cell). The increase in building blocks and resources accelerates bone healing. The ultrasound waves also encourage the cells to get rid of their waste products faster which also speeds up healing and they encourage increased blood flow to the fracture site (which helps reduce swelling).

As an ex-biologist,  I also do like that there have been FDA clinical studies (and several other studies in fact) that have shown benefits of ultrasound therapy (Azuma et al., 2001, J. Bone Miner Res; Cook et al., 1997, Clin. Orthop. Rel. Res; Dijkman et al., 2009, Indian J. Orthop; Heckman et al, 1994, J Bone Joint Surg Am; Martinez de Albornoz et al., 2011, British Medical Bulletin; Nolte et al, 2001, J Trauma). You can also see these Bone Abstracts from articles for proof! In addition, several ex-athletes as well as some nurses I have talked to stated that they did notice improvements when using ultrasound therapy. Nephew and Smith (the manufacturers) claim that in humans the Exogen 4000: heals 86% of non-union fractures, that it heals fresh fractures 38% faster, and that it heals fractures with risk factors 50% faster.

Hopefully Taj's next radiographs will confirm these findings!

So if you ever need an Exogen - feel free to email me for advice. I will be happy to share with you the name of my Ebay seller and I will likely have a working unit with at least 60+ good uses on it after our treatment!

We are heading down to VOSM for our 12-week check-up soon - so stay posted!