I’ve written more about injuries on my blog lately than I have about training or science or life. It’s just where I am in life. As I write this my left leg is strapped into a continuous passive movement (CPM) machine repeatedly going from 0 to 90 and back to 0 degrees. My leg is restless and as I glance at my stopwatch I see that I still have another 90 minutes of this tortured mechanical and completely painless hell before I reach my goal of 6 hours for the day. Its repetitive and boring, but yet it is also necessary, like much of recovering from an injury and subsequent surgery.
As I prepared for surgery my scientific curiosity came out in full force. After my first MRI, I consumed every article with the words chondromalacia (cartilage loss) and surgery (see pubmed list here). It drove me crazy that there is not a single best practice for this and that each of the approaches have major drawbacks. We can edit out genetic diseases, but can’t fix cartilage?
My injury (likely) began in Scotland (skip ahead a bit if you want injury only details). After a successful return to competitive ultras culminated with a win at the Highland Fling I decided I needed to explore more of the Highlands before attending the wedding of friends from my Copenhagen days which brought me to the northern parts of the UK. Northern it was, and in May that meant some significant snow at a mere 1200 ft. My goal was a 25-mile loop through the Highlands, but 4 miles in I was post-holing and moving at an inexcusably slow pace, which I vowed to make up for with aggressive downhill running. Poor strategy and my unnecessary risk taking resulted in a nasty fall in which I hit my left knee directly on the granite rock. With a gash of several inches that required stitches, but only received steri strips (I should have taken advantage of government healthcare), my running on the trip was done. In the back of my head I was worried that I did something more than cosmetic. That sort of impact does not go unpunished.
Fast forward several months and an occasional twinge would make its way into my left knee, but never pain and never causing me to stop. The fall semester of 2015, my first teaching, I was so busy it was near impossible to train. That spring I vowed to run “the” local race and managed to get into decent shape, but would be stopped from full on training by a left knee pain that would come on following a hard training session and reliable disappear with a few days off. My race suffered from the same pain a mile from the top of the climb. Time off, a trip to Europe, and then retraining again while in Boston I suffered the same pain, stopping me from running and lingering into my walks for several days.
Upon returning to Boise I vowed to get the problem fixed. My MRI showed an area of bone-on-bone contact where a small (2-3 mm) area of cartilage was gone. I also may have had some meniscus damage. The surgeon recommended no surgery. I could walk with no pain and could run 30-40 minutes several times a week pain free. As I already knew from my own research there were no good options and no guarantees. Lifestyle adjustments first. I’d become a more rounded endurance athlete – I could live without running as long as hiking, biking, and new sports like skiing and climbing could fill the gap.
I suffered again through a busy Fall and managed to break my thumb cross country skiing. But my knee was still hurting and not just running. Skiing and walking seemed to aggravate it. WTF, was I just overly sensitive? It was getting to the point of altering my quality of life. A weekend backpacking trip pain-free was impossible and so come spring I sought additional opinions. All opinions (those with an MD behind their name and mine) agreed that surgery was a good option and that the best of the worst options was a microfracture surgery.
So why are they all bad options? Well we are born with a specific type of cartilage in our joints called articular cartilage. This cartilage has the property of being able to absorb repetitive shock and allows gliding of bones against each other for the entirety of our lives, hopefully. Those that suffer osteoarthritis (bone arthritis) have degraded cartilage that causes the bones to rub, become inflamed and painful. Surgery for osteoarthritis is a temporary fix with many of moving on to total knee replacements, replacing the idea of restoring cartilage with removing the cartilage (and bone) altogether. This is because the cartilage that they restore or replace is not identical to what was loss in one way or another. However, I’m optimistic that I am not headed down that path yet as my injury lacks the pathology of arthritis and was trauma induced. Yet, the science is NOT super clear on this either!!!
Mircofracture surgery has been around for nearly 30 years with mixed success. In a not uncommon story in modern medicine it was developed before scientists really understood why it works (you only have to show that something works for it to get approved by the FDA). Now we know it works because of stem cells, or more specifically mesemchymal stem cells that are located in bone marrow. The surgeon goes arthroscopically into the knee and creates small holes in the bone where the cartilage is missing (in my case the femur). These holes allow the stem cell containing bone marrow to leak out of the bone and form a blood clot at the area of bone lacking the cartilage. The stem cells then transform into another type of cell, a chondrocyte. The chondrocytes are the cells in charge of cartilage. The cells are embedded within the cartilage and secrete the collagen and proteoglycan proteins that make up the cartilage. With microfracture we recruit and turn stem cells into chondrocytes that fill in the gap of cartilage. Unfortunately, the chondrocytes recruited do not secrete the same mixture of collagen and proteoglycan proteins contained in that beautiful slick and strong articular cartilage. Instead we get a different “type” of cartilage called firbogenetica cartilage. But it works, for a while. How long you might ask, and I certainly did? Well the data is not clear on that either.
So why did I choose microfracture if I knew it wasn’t going to make the right kind of cartilage (see a detailed review on the different techniques here). Well there were a few reasons. One is that it generally works and it works better for younger (<40), healthy, and normal weight individuals. So I’m optimistic there. Second, it keeps all the other options on the table. Other techniques involve taking a biopsy of cartilage from somewhere else and growing it up in the lab or putting it straight into the existing gap. These techniques work well for larger gaps, but you can only do them once and the replacement cartilage doesn’t always stick. Athletes have come back from microfracture before. Several NBA and NFL players have returned to play following the procedure, but many don’t as well. Most data actually shows no difference in outcomes with the various techniques in patient populations. Studies do show that the inferior cartilage breaks down though and perhaps I will get 10 years out of my imposter articular cartilage. Still all of this data is population based – I could be lucky and never have pain again, or in 4 years I might be under the knife again. Large studies with lots of people don’t tell you exactly how your unique situations will respond.
My PhD mentor always told me that I could spend 26 years being active or focus on competitive 26.2 mile races, meaning I was to jeopardize my long-term health for a short term athletic goal? However, I had running mentors who were older (and healthy) and that reasoning always felt like a false dichotomy and certain data does back that up. I certainly did not get here because of an over use injury but instead an underuse of my intellect. But now the question does seem relevant. When my doctor said that with this surgery I should be able to run again I was taken aback. I had actually being riding my bike and coming to grasp with the idea of coaching rather than competing. I was coming to grips with closing that door. But now…I’m not so sure as like many of you and others it has become a part of my identity, my meaning, and my passion. Not running has been a struggle, but then again 26 miles or 26 years. As I move forward with rehab and I plan to share the process. That much is known even if the place that the process is leading me to is not.
For more papers on various ways to deal with cartilage defects:
- Knee cartilage defect: marrow stimulating techniques.
- Surgical interventions (microfracture, drilling, mosaicplasty, and allograft transplantation) for treating isolated cartilage defects of the knee in adults
- Microfracture: State of the Art in Cartilage Surgery?
- A Randomized Multicenter Trial Comparing Autologous Chondrocyte Implantation with Microfracture
- Acute and Stress-related Injuries of Bone and Cartilage: Pertinent Anatomy, Basic Biomechanics, and Imaging Perspective