Ulnar collateral ligament (UCL) tears in pitchers have become relatively endemic to the game. While there seems to be a spike in the number of cases seen already in the 2014 season compared to previous years, what's more puzzling is the number of re-tears sustained and the short length of time in between these tears, seen in players like Atlanta Braves pitchers Kris Medlen and Brandon Beachy or Arizona Diamondbacks starter Daniel Hudson. While things can and do go awry in any medical procedure—grafts fail, complications arise operatively, postoperatively or during rehabilitation—you would expect that with the advances in medical technology and the improved understanding of the rehabilitation requirements for a complete return from the Tommy John procedure that current-day failures and redoes would be minuscule.
Are TJ surgery second timers a rarity? Using Baseball Heat Maps as are our data source, we find 43 pitchers (and Xavier Nady) with confirmed second UCL tears with surgeries, with a mean of 4.5 years between procedures; for those outlier averse, the median for time between procedures was 4.0 years. Of those 43, we find 26 that had between-surgery durations that fell below the mean and 23 that fell below the median, or 60 and 53 percent of our population of interest, respectively. In short, over half of the time, pitchers who succumb to a second UCL tear do so in short order. Anecdotally, 11 of these redo procedures have occurred in the last five years. Compare this to the full cohort given in the Baseball Heat Maps database of 530 confirmed pitchers who have had TJ surgery and we find 8.1 percent of pitchers who suffer a UCL tear and have surgery end up getting a second tear.
The reasons and causes for a UCL tear are numerous—poor pitching mechanics, too many pitches thrown, too many sliders, or even leverage and intensity of the situation when a pitch is thrown—and to this point, nothing seems to be the smoking gun of the root cause of all or even most UCL tears. Despite the simplicity of the elbow joint anatomically and biomechanically, the answer to this question remains complex.
Like many things related to injury analytics, the data available is sparse in the public realm and prevents robust inferences to be made; this is a necessary evil, as not only do organizations need to maintain secrecy over their product and personnel to maintain a competitive edge, but respecting privacy as it pertains to a player's medical history is of utmost importance. As such, we as Joe and Josephina Q. Public are left to thoughtfully grasp at straws when it comes to pushing paradigms and blazing analytical trails in the baseball injury world.
I'd like to share a straw.
In my previous day job, the effects of tobacco use on the success of orthopedic procedures—in particular, spine surgeries—both intra- and postoperatively were a constant cross to bear. Generally, smokers fared worse overall when undergoing orthopedic procedures. Anesthetically, smokers are more difficult to keep anesthetized and are more difficult to monitor with regards to their respiratory rates, blood pressure, and oxygen uptake. Surgically, they can often require more blood products operatively and can also take longer to recover, sometimes having severely delayed rates of bone and wound healing, among many other poor outcomes. Considering that roughly a quarter of all Americans are smokers, this is a growing public health issue.
Could smoking status play a role in some of the UCL failures and re-tears we have seen in baseball?
While we don't like to think of our baseball idols as fallible to the allure of a nicotine habit, the reality is that it is prevalent, both simply due to the national smoking statistics, but also the rampant use of smokeless chewing tobacco in the game.
While research on elbow ligament replacement surgery and the effects of smoking upon them are lacking at best, we can look at our question from the perspective of the effects of smoking on knee ligament replacement surgery. Researchers have turned to mouse models to look at the effect of smoking cigarettes on the healing process of the medical collateral ligament of the knee and have found that cell density, biomechanical function and gene expression of certain inflammatory processes and machinery were all altered in mice exposed to cigarette smoke, leading to delayed or deficient healing processes initially. Considering the process of recovery from ligament repair or transplant occurs in stages over the course of months and probably years, the tobacco use can lend itself to delaying or interrupting any stage of the recovery process. Turning our research to humans, a similar study performed looking at the effects of smoking on the repair of the anterior cruciate ligament of the knee found similar responses. In particular, reported frequency and intensity of pain was higher in smokers than non-smokers postoperatively. Subjective and objective reports of worsened ligament stability and laxity were found more frequently in the smoking cohort, lending thought to the idea that the effects of smoking could play a role not only operatively, but also in rehabilitation, as the aggressiveness and length of the rehabilitation period for smokers could potentially be altered to compensate for the effects of tobacco use on the regenerative processes after surgery.
Like many things in research, the attempt in answering a question often provides more questions en route to finding your answer; this exercise is no different. While the elbow and knee are similar in that they are both hinge joints and thus share many similarities biomechanically and physiologically, the fact that the knee is a weight bearing joint (while the elbow isn't) does give pause to how much of the above mentioned results can be applied to elbow ligament replacement procedures. My guess is a reasonable amount, but again, the aforementioned caveats still apply. Also, this research is based on smoking cigarettes, so the amount of inference we can make and apply to the effects that chewing tobacco might have is questionable as well, as it still isn't clear whether the negative effects seen from smoking arises from exposure to nicotine or other toxins found in cigarette smoke. In the final research article linked, there is a brief discussion of how the application of the aspects of timing and intensity of rehab programs plays a role in possible delays in recovery or even re-injury, but that their data doesn't allow for this assessment. Yet, it does lend credence to the idea that smokers might need more time to recover from Tommy John surgery and that perhaps those who suffer a second tear so soon after their first UCL injury might have enough of a history of smoking (or tobacco use in general) that would facilitate a medical staff to take a more conservative, more time appropriate course of rehabilitation in order to compensate for the deleterious effects of smoking on the repair mechanisms of the body.
In the end, this is all spitballing for now; the data necessary to perform this type of research properly is too sensitive to divulge on a number of levels. Not only is it not available to the layperson, but a number of stigmas are abound in the questions that need to be thoughtfully and honestly answered by players and medical professionals alike for it to be of public consumption anytime soon or for the analysis to be ground truth. However, the issue is of great enough importance to keep questioning what data we do have and to keep thinking outside of innings limits and pitch counts, as we strive to built the perfect pitching beast, or at least keep the beasts we have healthy.