Sunday, July 24, 2011

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!


  1. Please let us know how Taj faired with the Exogen Treatments and if he healed.

  2. Hello everyone,

    First off great post. As I've supposedly been prescribed one of these, I've been doing further research into it, as I have yet to be contacted by a rep. Anyway, I happened to come across one from someone I know and I sure enough, it was dead. A little further research revealed replacement battery packs on-line for under $50. Now, I'm not squeamish so "hacking" at a device like this doesn't give me any grief. Disassembling it was a cinch as was replacing the battery. The unit at most costs less than $80 bucks to make. (I was surprised by the simplicity of its PCB and other underlying components. In summary, don't get taken to the cleaners on these. They're easy to fix and if you have problems, ask your local geek.

    1. Same experience here.

  3. I was going to try the same thing, but a friend who is a doctor said that to take the back of these you cant just slide of a battery cover. They are not intended to have the batteries replaced. You need to tear apart the unit, and one touch on the wrong spot on the back and the unit will not work correct. Further, the batteries that you can buy, are the same battery style and size, but they dont have the circuit board affixed to the battery that the ones the Smith and Nephew factory use. It was explained to me that without that circuit board the unit will not output the correct frequency.

    I did find that you can rent these at
    There website does not say anything about using them for a pet, but I am sure they would rent from you. At least with them the units are sanitary and guaranteed against battery failure.

    1. Yeah the battery circuit board thing doesn't sound very likely to me. I replaced mine and tool the pack apart to see what the batteries were (as I built my own pack from single cells) and saw no circuit board. If there is anything built into the battery it will be the standard short-circuit/over-current protection boards, which shouldn't affect the frequency.
      No idea where the "one touch on the back will wreck it" bit comes from either. Perhaps the standard caution about static on any computer devices, but that's not a major risk.

  4. You can rent these at
    and they are gauranteed to work for the rental period.

  5. Buy one of these off of ebay or do a google search. Exogen rental rates are ridiculous, you can easily buy a unit far less than what they charge and can resell it when you are done.

    1. On the other hand, exogenrental guarantees sanitary machines and have the equipment necessary to ensure sanitation.

  6. Thanks so much for this post! I was prescribed one of these machines a few days ago for a broken foot, but my insurance company only pays 50%, and my share would have been $1250! I found a couple of new, unused units on craiglist, and one had a picture of the label showing the serial number. I was wondering how to find out when the unit was manufactured when I came across your blog. It's a few years old, but I'll only need it to work for a month or so, so I'm not too worried about that as long as it turns on and is clearly working. It was manufactured a few months after the end of the recall, so that's good too. I also wouldn't have known that the unit shows the number of uses, so I'll be able to confirm that it truly hasn't been used before buying it. The unit is for sale at $200, a huge savings over going through my insurance.

    I'm glad that Taj is doing well, I read the story about how he broke his leg, and it's horrifying!

  7. I bought one for $130
    It was also dead, would not power up.
    I then ordered a battery online, that was $65
    I took the unit apart carefully, but somehow screwed up the on and off button.
    I tried again, and got that to work, now it works but does not make the sounds that it did when it was functioning initially.

    Not sure its working.

    I am out nearly $200 and not willing to try another battery, just seems like another $ risk

    I have found an outfit that rents these

    This seems like the way to go.

    The warranty is for the entire rental period you agree to, and though there is a deposit
    ( not unexpected due to the value of the machin e)
    you get that back if you return it on time

    check out

    1. Absolute rubbish! It is easy to replace the battery. This is obviously a sales rep from exogentental.

  8. Thank you for taking the time to post this.

    I have a question about the system that I managed to buy. When connected it does start countdown and shows the "pulse icon" but it also shows the "triangle/exclamation mark icon" and beeps throughout the treatment.

    Is this supposed to occur? Is it working?

    1. Sounds like the battery is dead. That's the same behaviour I had when mind died at some 300 uses. Although the countdown paused while beeping for me.

  9. I too purchase one used.
    It stopped working after 3 uses
    Now Doc says 1 more month of not healing and I can get one from insurance
    but my deductible is $500
    The ones at are guaranteed to work, and cost less than my deductible
    I am going to rent one from then so I can get started right away.
    I think where people are confused about the rental price is that there is a deposit you are charged but get back when you return the machin

    1. As someone mentioned earlier...find your local geek and you will have an exogen machines that works indefinately. They should work forever considering the price that is charged for the initial unit. I think this person should stop trying to promote their rental company with misinformation.

  10. Hello,
    Jumping in late here. I know you can't ask your dog :) but if anyone knows, what do you feel when the Exogen 4000 is working? do you feel the the thing "pulsing" or anything like that? It looks from from above you are not supposed to feel the ultrasound waves, but I'd would like to be sure. I used mine and it seemed to work ok, but I didn't feel anything during the 20 minutes it was on. Thanks.

    1. Mine is brand new and my sales representative said that you WON'T feel or hear anything. I didn't feel a thing except the coolness of the gel on my skin!

  11. Hi There,
    You wouldn't feel any pulsing or other physical indicators the unit is working.

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  13. Hi there! I just stumbled upon your post after looking for anything exogen related. I'm currently using a newer version of the exogen 4000 bone stimulator...I'm on day 19 of what the Dr said will most likely be 90 days of treatment. Since you have a science background I wanted to ask your studies have been done for an actual answer so just your you think using the machine more than once a day will do anything more for the bone? I have a fractured sesamoid that started 9/10/15 and still isn't healed...I'm hoping the BGS does its job so I can avoid surgery. What are your thoughts on using it 2 or even 3x a day?

    1. FWIW, my surgeon told me to do it twice a day. No idea if that was based on any scientific knowledge or just a "more should be better" assumption.

    2. Hiya - good to see a recent post on using Exogen. Good luck with your healing! I have a non healing fracture and am researching Exogen. Did you or anyone else manage to get it on NHS? From what I can gather, the NHS will only provide it after 9 months of delayed/non healing? Anyone know situation re Exogen providers in Dorset? Re using it once or twice a day - I read USA posts from users who said the Exogen Rep advised twice a day. Anne

    3. My insurance paid for mine after 12 weeks,100% coverage. I fractured my sesamoid and it's not healing... I've been in an aircast for 6 months and using the BGS for 65 days so far. I don't feel any improvement since I started the bone growth stimulator... First my Dr said we'll do it for 90 days and now pushed it back to 120 days.... I see a surgery in my future.

    4. Hi Kellystoo, I'm curious did you ever heal and did you have to get surgery? My daughter is in the same boat with a sesamoid.

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  16. One month ago, I rolled my ankle and ended up with a clean through non-displaced fracture (avulsion fraction in the tuberousity of the base of my 5th Metatarsal). My insurance would only cover half of the cost of the Exogen bone stim which is now $5,000, so I just bought a used unit with 31 uses on it from Ebay for $225. Started using it 2 weeks after the fracture, and just saw my Ortho today for my 4th week checkup. He says whatever I'm doing, I'm doing it perfectly right because there's already soft callus formation. He originally told me I'd be needing the CAM boot for 6 weeks, but now says I can get off the crutches today, and off the boot by next week. Then, a carbon fiber shoe insert in my normal shoe for another 3 weeks, and I should be back to normal hopefully.

    I would def recommend getting the Exogen, as I think it helped a lot. I am a bit overweight 47 year old that doesn't exercise much and also has borderline high blood sugar levels, so not exactly the best candidate for best bone healing, so either I'm lucky or this bone stim works.

  17. It didn't work :( I just had my second Cortisone shot yesterday... This begin September 2015 ... I had x-rays yesterday and even after all this time it's still healing. He showed me my x-ray from October and yesterday and while mild it's still healing...Long after my bone growth stun was over. I have to be honest, while my 1st Cortisone shot was working I didn't do anything to help it heal...I wore my insoles and worked out as I would have before the break... He said when this shot wears off we'll consider surgery if there isn't much progress. He's been ready to remove the bone for a while... I'm just holding off bc there is never a good time for surgery when you have a 4 & 7 year old.