Regrowing my Tibia, Part Two

*Disclaimer* There is content (including images) in this post that some people might not want to see, including some pretty epic x-rays, an incision with surgical staples, and pin sites (holes made in the skin with surgical pins that are used to attach something called an external fixator (a metal frame) to the body. Some people might find these pictures gross. If you don't want to see these things, please stop reading!

 

When I first found out that I was ineligible for a bone graft (too much of my tibia had been removed for a bone graft to be viable), I was confronted with the prospect of having to regrow my tibia. Along with this news came a confusing set of concepts and terminology, like external fixation and distraction osteogenesis. It took a while for me to get my head around what would be happening to me over the following months and to grasp the concepts behind it. There were a lot of tears, many questions, and generally a lot of confusion in those first few days after I got the news. Given my own experience, it makes total sense that other people at the start og this process or watching a friend or family member go through it are just as confused as I was. I wanted to help make this easier for other people going through this because I know how difficult, daunting, and scary something like this is. So, several weeks ago I published a post outlining the basic concepts and definitions related to the process of re-growing bone. I tried to do so in way that doesn't require a medical degree. After all, there is nothing worse than having a doctor spew a bunch of incomprehensible medical mumbo jumbo at you in the middle of a personal medical crisis. So I hope that the information I provided is clear and easy to understand. If not, I apologize. For those who haven't read that post, a link can be found here. Now that the terms and concepts have been defined/explained, my next gaol it so explain how the whole thing actually works, using the information given to me by my doctors (and occasionally gleaned off the internet) and my personal x-rays. That is what this post is about. So here goes...

 

Without going into too much detail about how I wound up in my current situation -you would be reading this post for a very, very long time if I told the whole story from the beginning- here is a basic run down of how I ended up where I am now. At the start of 2006 I broke my leg. I suffered a compound fracture, meaning that when my tibia broke it pierced through the skin. My leg took a long time to heal, there were complications and even after it healed my mum and I knew something wasn't quite right - there were signs and symptoms of infection on and off for many years although we didn't know that's what was wrong at the time. In 2011 I was finally diagnosed with chronic osteomyelitis, which was treated with surgery, two months of IV antibiotics and fifteen long months of oral antibiotics. My doctors believe that I got the infection when bacteria entered my leg through the wound left by the compound fracture. Based on scans in January 2013, my doctors thought the infection was gone and I gladly got on with my life and put the whole thing behind me. By the middle of 2014, however, I knew something was wrong. By the end of the year I went back to my infectious disease specialist but it wasn't until February 2015 that the relapse of the chronic bone infection was confirmed. After discussing things with my surgeon, I knew that surgery would have to happen at some point but was told it could likely wait a few years until I finished school and got a good nursing job. Unfortunately, by the end of May it was clear that surgery could not be postponed much longer. Thus, surgery was planned for the end of August. At that point, the plan was to cut out the infected section of my tibia, replace it with bone cement, be pumped full of antibiotics and wait several months to see if th infection would return, and then have surgery to replace the missing section of my tibia with a bone graft (from both a cadaver and one of my hips). This is how I things where supposed to happen.

So on August 23, 2015, I had surgery to remove the infected section of my tibia. When a piece of bone is cut in two, this is called an osteotomy. In order for a piece of bone to be cut out, an osteotomy has to be performed twice, once on either end of the part that needs to be removed. The surgery went well - my surgeon thought that he got good margins, meaning that he not only cut out the infection but also enough healthy bone around the infected section that there shouldn't be any infection in the remaining bone. The surgeon, however, had to take out more bone than expected. He explained that the upper limit for a bone graft to be viable was around four to four and a half centimeters. He roughly estimated that he took out six centimetres of my bone. The plan was still to pump me full of antibiotics and wait several months to see what happened, but after that I would need to get an external fixator so that we could re-grow my bone (distraction osteogenesis) by means of bone transport, which is the process of moving/transporting a piece of bone to allow new bone to fill in the gap, thus lengthening the bone a little bit at a time (progressive lengthening).

This is my leg after the surgery in August. You can clearly see the bone cement holding the two ends of my tibia together. You can see where the osteotomies, or the places where my bone was cut through (two different spots), were done. You can tell that this was surgically done rather than a by a fracture/break because of how smooth the ends of the bone are.

Front view

Below is the rough estimate that my surgeon did on one of my x-rays. Given this, he said he had removed about six centimetres of bone.

Side view





After the surgery in August, things went as planned. I was pumped full of antibiotics until the start of October and then the great wait began to see if the infection would rear its ugly head. Fortunately, there were no signs of infection and surgery was scheduled for the end of November.

On November 25th I had surgery to get my external fixator. Despite complications with pain and low potassium after surgery, the surgery itself went well. The procedure took two hours. In that time, the surgeon removed the bone cement from my leg, reamed an IM nail (intramedullary rod) through my leg, and attached an external fixator to my leg with pins that were screwed into my bone. In order to place an IM nail, the kneecap needs to be pushed out of position so the nail can be inserted through the top of the tibia and reamed through the center of the bone. An IM nail is generally the length of the entire bone. In my case, the IM nail was placed normally with the exception that there was obviously a gap half way down the bone. This wasn't a problem; it just meant that the surgeon had to be careful that the IM nail was properly aligned in the top section of bone (by my knee) so that it would also enter the bottom section of my tibia (part attached to my ankle) properly. Before the pins of the external fixator are screwed into the bone, a drill is used to drill the necessary holes into the bone. During surgery, my surgeon found out that I was actually missing 6.5 cm on bone instead of 6 cm, which meant that it would obviously take a bit longer to grow the missing section of bone than we thought it would.

Here are the x-rays I had taken during my post-op appointment.

Front view

Side view. The loose piece of bone is not fully aligned with the upper part of my tibia because it has to follow the curve of the IM nail as it is transported downwards and properly meet up with the lower part of my tibia.

This is what my external fixator looked like after it was put on but before I started adjusting it.

And here are some pictures of my pin sites:

My pins sites like to drain. Sometimes a lot...

I had one very long incision (about 25 centimeters long) running almost the entire length of my lower leg and smaller incision on my knee from the IM nail placement. I also had several small incisions (about one centimetre long each) at either of my leg. These incisions where made so that the screws necessary to hold the IM nail in place could be inserted. You can see one of these incisions to the left and near the top of the really long one. Depending on what type of fixator you have or why the procedure is being done, you might not have such a long incision or need an IM nail; it is possible to lengthen or re-grow bone without one.

I have a Stryker Hoffmann external fixator with a MonoTube Triax external fixation system. I actually found the PDF files explaining how to put it together and surgically apply it online! My external fixator is made of various parts: 1) there are four pins connecting the fixator to my leg, two at the bottom of my leg and two at the top 2) the pins at the bottom of my leg (right above my foot/ankle) are connected to  clamp. This clamp is connected to kind of a metal rod that has markings, like a ruler, on the front of it. These marking et you see how much you have adjusted the fixator/bone you have grown 3) the two pins below my knee are also attached to a clamp. This clamp is attached to another metal rod, but this rod is hollow, like a tube. This tube can fit over top of the other rod. It has a knob at the end of it which is visible in the picture above - it is silver and can be turned both clockwise and counter clockwise. It also has what looks like a large screw or bolt in the middle of it.

I am now going to explain what's what on my x-rays and how the external fixator actually works.
To do so, we go back to the x-rays I just posted. I have edited one of them with arrows/circles/etc., to help explain things. Here we go:

Side view with explanations

The piece of metal running through my leg is the IM nail. You can see the screws at the top of it, securing it to my leg. This nail, plush the screws, keeps everything aligned and prevents anything from moving.

 

At the top of the x-ray, under the screws holding the IM nail in place, I have drawn a green squiggly line. This is where the surgeon performed the osteotomy, thus cutting a chunk of bone, which I have pointed out with a purple line. This bone is not connected to anything in my body and is held in place by the two pins drilled into it.

 

To sum things up so far, the IM nail holds everything together and the pins drilled into my bone at either end of my leg are attached to the frame on the outside of my leg. The pins at the top, which are attached to the external frame, prevent the loose piece of bone from moving around. Altogether, this is a pretty sturdy construction - the combination of the IM nail and the outer portion of the fixator, which prevents the parts of the leg with pins in tem from shifting around, keep everything in proper position. If I only had the IM nail, the loose portion of my tibia would move around. If I only had the fixator, which is only attached to the bottom of my tibia and the loose chunk of bone in my leg, things would probably move out of alignment the minute I started adjusting the fixator because nothing would be secured to the top of my tibia! So I need both the fixator and the IM nail to keep things in their proper position. People with other types of frames, like Ilizarov, Taylor spatial, or hybrid frames may not require an IM nail.

 

At the top of the x-ray, I have drawn a red circle around the knob I turn to adjust my fixator. The knob is attached to the outer tube that I mentioned earlier. Within this tube, there is what appears to be a giant bolt. When I turn the knob, this bolt turns with it. The fixator acts like both a nut and bold system, and a tube within in a tube at the same time. As I turn the knob on my fixator, the bolt screws itself into the nut, which is the hollow portion of the inner tube; the outer tube/top of the fixator simultaneously moves over the bottom part of the fixator. Because the top part of the fixator is attached to two pins and the other end of those pins are attached to a part of my tibia that is not physically connected to my body, that loose piece of bone moves downwards when the outer tube portion slowly moves downwards. Meanwhile, the screws at the bottom of my tibia and the IM nail hold everything else in place.

 

To sum things up so far, I turn a knob on my fixator. The top portion of the fixator moves downwards over the bottom piece, like a tube within a tube. Because the outer tube is attached to a loose chunk of bone (see purple line on x-ray) by two pins, that chunk of bone also moves downwards. When I refer to turning the knob on the frame or doing the turns, this means I am making adjustments to the fixator. The turns refers to the clockwise or counter clockwise movement of the knob.

 

Simple enough, right? But boy does it take a lot of words to explain!

 

Let's get back to the osteotomy for the moment. The osteotomy is located where I drew the squiggly green line on my x-ray. As we already established, the loose chunk of bone moves downwards when I turn the knob to adjust the fixator. When this happens, the space between the upper portion of my tibia, which is still connected to my knee, and the loose piece of bone increases. This is done in very tiny increments. I adjust my fixator twice a day. I turn the knob half way round, which equates to 0.5 millimeters of movement of the outer tube and therefore bone, in the morning, and a quarter turn at night, which makes the gap grow 0.25 millimeters larger. As a result, it takes two weeks to grow one centimeter of bone. Depending on the individual and how quickly their body can produce cartilage, bone can be grown at a slower or faster rate. Generally, bone is grown between 0.75 mm and 1 mm per day. Thus, the bone is being transported downwards and lengthening is done progressively, hence lengthening progressive. The cells between the two ends of bone are tempted to bridge the gap between them. When these cells bridge the gap, they also start to grow and produce more cells. The result of this is cartilage. Cartilage is the precursor to bone. My surgeon explained to me that cartilage is like pizza dough - it is stretchy, so the more I adjust my fixator the more the cartilage will stretch to keep bridging the gap between the two ends of bone. The only risk is that your bone grows and heals faster than you adjust the fixator, which would allow the two ends of bone to knit together prematurely. Surgery would be required to fix this (another osteotomy). After many months, the cartilage grows into bone. This is the process of distraction osteogenesis - slowly pulling bone apart in order to grow new bone. 

 

And that is how new bone is grown! I turn the knob on my fixator which moves the outer tube portion of my fixator downwards. This simultaneously moves the pins and loose section of bone downwards, increasing the gap between the ends of bone and forcing those ends to bridge that gap. The gap is slowly filled with cartilage each day and that cartilage eventually turns into normal healthy bone. Yay! The human body truly is an amazing thing!

 

Now that I have explained how new bone is grown, which can be done to re-grow a missing section of bone or to increase the length of a bone, and what's what on my external fixator and x-rays, it is time hem out some of the smaller but equally important details and then see the process in action.

 

As previously mentioned, I have to turn a knob on the end on fixator in order to make adjustments. This is done with a 0.7 mm wrench, pictured here:

My trusty little wrench. My surgeon said if I lose it I can go to a hardware store and by a new 0.7 mm wrench.

If I were trying to lengthen my leg, I would need to lengthen my tibia (and fibula, but I won't talk about that because I don't actually know how that part is done). This would mean that I would have to cut a healthy bone in two (osteotomy). A fixator would be attached to the leg by pins, two or more on either side of the break. These pins would be close together and the inner tube as far into the outer tube of the fixator as possible. The person undergoing this procedure would turn the knob on the fixator counter clockwise, which would slowly start sliding the tubes apart, thus increasing the distance between the parts of both the fixator and the bone and allowing new bone to fill in the gap and the bone and limb to be lengthened.

 

I am kind doing the opposite of this. I am trying to grow bone but maintain the length of the bone. My bone is broken down into four sections, not two like in the previous scenarios: 1) intact bone attached to my knee 2) loose piece of tibia attached to my fixator 3) missing section of tibia 4) intact bone attached to ankle and fixator. The IM nail runs through all of this. I turn the knob clockwise, which makes the outer tube slowly slide over the inner portion, bringing the clamps and pins closer together. Like the process to lengthen a limb, doing this also increases the gap between two pieces of bone, promoting cartilage formation in that gap. But instead of lengthening my leg/tibia, the loose piece of bone moves towards the bone attached to my ankle, which is held in place by both the fixator and IM nail, thus preventing things from moving around and losing alignment.

 

It is also possible to shorten a limb, but unfortunately I have no knowledge that I can provide about this.

I started doing "the turns" or making adjustments to my fixator on December 3rd. As I previously explained, I make 0.75 mm worth of adjustments a day. When you first start making adjustments you will not see any bone growth. This is because the fixator has to be under a certain amount of tension before the bone in your leg will move. This portion of adjustments is referred to as turning out the slack. Once this is done, you will be lengthening the gap between the pieces of bone, aka transporting bone. As you adjust the frame and the outer portion of the fixator, the pins attached to the fixator and bone obviously move along with them as well. As a result, the pins tear through the skin. This is called tracking. But won't that hurt? Yes, but you will be given good pain medication to make you more comfortable. Will this take away all of the pain? Unfortunately no, not always.

One last note before I continue with my x-rays. This process is usually done from the top down - the loose chunk of bone is located nearer to the bottom of the leg and it is transported upwards. As a result of where my infection was and bone had to be removed, I am doing the bone transport the other way around - from the top. The procedure (bone transport/distraction osteogenesis/lengthening progressive) is done as normal, but in the opposite way my surgeon had it done.

But now onto the fun and rather amazing part - the x-rays!

These are the first x-rays I had taken after I had started doing the turns. They were taken on December 18th. As you can see, the gap of bone between the upper portion of my tibia (attached to my knee) and the loose portion had increased.

Front view

Side view

Bone is very dense and solid. This is why is shows up on x-rays.  New cartilage, the precursor to bone, on the other hand, does not show up on x-rays right away. As the cartilage grows and begins to turn into bone, it slowly starts to show up as a while fluffy cloud. As the transformation into bone continues, this white cloud looks more and more solid on the x-rays. Therefore, as you adjust your fixator, you will not all of a sudden see lots of healthy new bone. It takes between 6-9 months for the cartilage to have fully turned into bone. And obviously the parts of the new bone that are grown first will look like healthy bone faster than newer areas of bone growth. As a result, you might see nothing at all at first, then a bit of white fluffy cloud at the end you started growing bone at and nothing elsewhere. As time and the lengthening/bone growth process progresses, you will see more and more white stuff in more spaces than in previous x-rays.

In the x-rays above there doesn't really appear to be anything in the newly formed gap. My surgeon reassured me that the cartilage is there, it just can't be picked up by the x-ray. He has patients come in for frequent checkups at the start of the distraction osteogenesis process in order to help ensure them (and him of course!) that things are actually happening rather than two ends of bone simply being pulled apart, leaving an empty gap.

In these x-rays you can actually start to see a tiny white cloud which is new cartilage! My surgeon was surprised to see this so early on and, of course, very, very pleased which in turn excited my mum and I.

I circled this area in the picture below:

Side view. Fluffy white new bone in red circle.

My next set of x-rays where taken on January 8th. The x-rays show that the bone transport is still occurring thanks to the adjustments and the fluffy white area has grown a bit and it getting darker.

Front view

Side view

Here is a close up of the bone growth:

Side view. New bone growing!

Side view. New bone growing in red circle!



My latest set of x-rays was taken at my appointment with my surgeon on February 5th. They show that the loose piece of bone has been transported over half the length it needs to. The outer tube portion of the fixator has now moved pretty far over the inner portion of the fixator, and the pins and clamps are closer together than ever before.

Front view



Side view. You can really see the new bone formation at the top of my leg!

In these x-rays you can clearly see the new bone growing at the top of my leg, where the bone growth first started. You can also clearly see a thin white line that outlines how the loose piece of bone was transported down my leg - this was not done in a straight line (the IM nail is slightly curved). Here is a close up of these white lines:

At the point that these x-rays where taken, I still had about another forty days, or 3 cm, of bone to re-grow. I scheduled my next appointment for March 4th. My surgeon explained that things start to become a lot more painful at the three centimeter mark, and was he ever right!

 

The bone growing/transport/progressive lengthening portion of re-growing the missing section of my tibia will end when the bottom of the loose piece of tibia meets up with the bottom piece of my tibia. This is called the docking site. When the two end of bone meet, it is like having a freshly broken leg. The ends need to knit together just like the end of a fractured bone would need to in order to heal.

 

In order for the ends of the bones to heal properly, something called progressive loading needs to be done. This requires adjusting the frame more than is necessary to simply fill in the missing section/gap of bone. Once lengthening and/or bone growth is complete, the fixator is adjust even more, thus putting pressure on the bone and forcing the two ends very, very closely together, even a little bit too much. My surgeon will keep the fixator adjusted in that manner (with pressure on the bone) for about two weeks, hopefully giving the loose ends enough time to knit together and start to heal. He also said that the compressive loading stage is the part of the entire process that will hurt the most. This makes sense, given that you are squeezing the ends of bone together really tightly, although it seems kind of unfair that the hardest part comes after an already long, painful and tiring process. But my surgeon assured me that I will get good pain medication during that time in order to manage the pain effectively.  I am not 100% sure what will happen right away once those two weeks are up, but I would imagine that the fixator would be adjusted back to the required amount that needed to be lengthened (thus removing pressure from the bone) in order to see if the ends of the bone actually knitted together. Please don't quote me on this part, because I am not exactly sure.

 

What I do know is that once the compressive loading is done and the surgeon is happy with the results, he will schedule surgery to remove the fixator. Depending on the results, one of two things could happen: 1) I have surgery to remove the fixator and a small plate put in to help the two ends of the bone stay attached together or 2) I have surgery to remove the fixator and a bone graft from one of my hips to fill in any gap there might be between the two ends of bone that were supposed to meet. It is also possible that the loose end of bone, which is meant to knit to the bottom of my tibia, could bounce back once the fixator is removed (the tension that the fixator created would be removed, which would require a second surgery to fix through a bone graft. I am really hoping that everything heals properly!

 

One of the really neat things about my how I am re-growing my tibia is the recovery period. With, for example, an Ilizarov frame, the frame remains attached to your body much longer than the time needed to regrow bone. If you want to grow 1 mm a day and need to regrow 3 cm of bone, it would take 30 days to regrow. It takes twice as long to harden/mature fully harden the bone as it does to initially grow, so after the bone is grown there would be an extra 60 days with the fixator before it would be removed. That means 90 days of pain, discomfort, inconvenience and infection risk. If the same scenario -1 mm/day for 3 cm- was done using the fixator and an IM nail, it would still take 30 days to regrow the bone, but the fixator could be removed much sooner. This is because the IM nail would provide the support necessary while the bone matures, unlike an Ilizarov frame which is the support and therefore cannot be removed until the bone is fully mature. When bone is grown over an IM nail, this is called lengthening over nail. There is also a process called lengthening then nail, which means taking placing and IM nail once bone growth is complete, allowing the fixator to be removed sooner. There are benefits and drawbacks to each method. Given the dates that my surgeon gave me, I expect that the surgery to remove the fixator will be at the end of April or in the first week of May. I could, of course, be wrong, but if I am I don't think it is by much. Of course, things can still go wrong, but here's to hoping they continue to move forward as they have over the last few months!

 

And that my friends, is how I am re-growing the missing section of my tibia! It really is quite amazing and even mind boggling. The body has an absolutely amazing capability to heal itself.

 

The really cool thing is that even if you have a different type of fixator than the one I have, the general process remains the same. You might have a larger frame, more pins and pin sites or have to adjust more knobs at different times of the day or more or less frequently, but the principles behind bone growth are universal. XD

 

I hope that this post has been information. I know that it really is quite long, but I wanted to make sure I covered everything. Even so, there are likely things I have forgotten. If you do have any questions, feel free to comment and I will do my best to answer them.

 

And finally, I wish all the best to anyone else going through process, or watching someone go through it. This process is neither fun nor easy. In fact, it is without a doubt the most difficult thing I have ever had to do in my life -physically, emotionally, mentally. It just down right sucks! I can't say it gets easy, because nothing about fixators is. Nor can I tell you to be brave and keep your chin up, because that is so incredibly difficult to do in a situation like this. And I, for one, am not always brave and upbeat, even if I try to be most of the time. It is not healthy to ignore how such a difficult situation truly makes you feel. I can't even say that this will fix all the problems with your leg (or arm, because this process can be and totally is used on arms as well!), because I don't know that. Nobody does. This entire thing is risky and has no guarantees. What I can say, however, is that it will be worth it if it is successful. It is the ultimate accomplishment - to regain health once it is lost and to be able to walk. And without a doubt, this trying process makes you a more patient, compassionate, empathetic person. Despite how shitty this all is, because it really is, that is still worth something in my book.

 

Oh, and just in case anyone is curious, here are a few more pictures of my fixator: