On the use of lubricating injections in Major League Baseball

As reported by many news outlets over the weekend, Los Angeles Dodgers starting pitcher Zack Greinke received a lubricating injection in his pitching elbow at some point last week. It is reported that Greinke has now received this type of injection in each of the last three spring trainings. For Dodgers fans, it is being classified as something that shouldn't be worried about because it is considered a "precautionary measure to prevent annual spring dead arm." However, given his elbow history (inflammation in March 2013, soreness in August 2014), I'm not entirely sure that the injection should be completely dismissed as a mere afterthought.

While I couldn't pinpoint exactly what Greinke received this time around, I originally hypothesized that it was hyaluronic acid—an injectable product with currently only one FDA-approved indication: osteoarthritis of the knee. Upon further review, it appears Greinke received Orthovisc (a brand name product of hyaluronic acid) in previous years, so it is not unreasonable to believe that he received it again, or at least a similar formulation to it (such as Hyalgan, Synvisc, or Euflexxa, among others) So, what exactly is a lubricating injection and what does it do?

Per Micromedex of Truven Health Analytics (requires subscription):

"Hyaluronic acid, also known as hyaluronan, is a high molecular weight polysaccharide derived from chicken combs that is used to relieve joint pains. It is necessary for the joint to work properly and it exerts its effect by replacing the depleted hyaluronan, which acts as a lubricant and shock absorber, in arthritic joints."

Essentially, a human joint (i.e. knee, elbow, etc.) contains synovial fluid, and hyaluronic acid, an integral component of synovial fluid, helps promote this fluid's lubrication within the joint structure—subsequently allowing for smooth and painless movement when called upon by the human mind. With continuous use (such as throwing baseballs on a regular basis) of a joint, it is not unusual for cartilage to wear down and for hyaluronic acid levels to decrease—with joint pain surfacing and becoming a physical limitation.

All that being said, Greinke's case is especially intriguing. After failing to find anything useful in a Google search, I asked Drew Silva to delve through HBT's injury database, and he couldn't find a single reference to a pitcher (not named Zack Greinke, of course) receiving a lubricating elbow injection, either. Now, there are some cases of baseball players with knee pain receiving such an injection: Josh Hamilton in 2010 and Joe Mauer in 2011. NBA point guard John Wall found these injections useful back in 2012 when he was dealing with knee pain of his own. It doesn't stop at knees, either, as everyone's "favorite" NFL quarterback, Brett Favre, received a series of lubricating injections in his ankle back in 2010 and former Red Sox third baseman Mike Lowell received such injections when he was dealing with painful hips.

Now, the number one thing to remember regarding lubricating injections is that they are not curative—meaning they do not fix the underlying issue, but rather only treat the present symptoms (in this case, pain). The current contract of 31-year-old Zack Greinke runs through 2018, and the last time I checked, despite being a tremendous hitting pitcher, his primary responsibility will be to throw baseballs effectively for the entirety of said contract. Also, ideally for Greinke, he will sign another contract after his current one expires.

If Greinke is already receiving yearly lubricating injections, what does that say about the long-term health of his throwing elbow? Of the players listed who have also received these injections, it appears they found use from them temporarily but then moved forward physically without the need to return to them regularly. This could always be a case where Greinke, and the Dodgers medical staff, is "ahead of the curve" by scheduling these injections to help prevent "dead arm" while his elbow is actually structurally healthy. Given that he has had elbow issues two seasons in a row, this is definitely something worth keeping an eye on, especially given the fact that there is a good chance the Cardinals will meet the Dodgers in the playoffs yet again.

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I must give credit to my school's Micromedex subscription because it allowed me to include hyaluronic acid's official mechanism of action, something that has not been readily included in previous articles on the subject matter. As I stated above, I cannot be completely sure that Greinke received hyaluronic acid, but the underlying mechanism behind lubricating injections nonetheless remains the same.