What is Tommy John Surgery, and What Are the Risk Factors? (Part I)

Tommy John surgery is a daunting procedure that affects athletes from all kinds of sports — but, it’s most common for baseball players and pitchers, especially those in the MLB.

According to the statistics, the number of players who have gone through Tommy John surgery has steadily increased over the years. While the frequency of cases fluctuates depending on the time of year (watch out during the peak of baseball season!), reported cases of elbow injury and Tommy John surgery have continued to trend upwards.

So, it’s high time we learned about the specifics: why do elbow injuries happen, and what factors necessitate undergoing surgery? And, what can athletes do to prevent these problems from happening in the first place?

There’s a LOT of detail that goes into answering these questions, but we’re nothing if not thorough! Today, we’ll be diving into what Tommy John surgery is and why it happens. (Keep your eyes peeled for more blogs about recovering from the procedure and methods for injury prevention later on!)

What Exactly is Tommy John Surgery?

Tommy John surgery is the more common name for the specific surgical reconstruction of the medial ulnar collateral ligament (MUCL) of the elbow joint.

Understandably, that name was a mouthful for most people, so it’s more commonly referred to as “Tommy John” surgery, named after the first baseball pitcher who actually underwent the surgery back in 1974.

Your MUCL is the ligament that runs along the medial side of your elbow joint. (If you want to get granular about it, it attaches to the medial epicondyle of the humerus to the medial coronoid process of the ulna.) This ligament plays a key role in stabilizing your elbow, particularly so you can avoid valgus or “inward” bending at the elbow during movement.

Unfortunately, research has shown that the MUCL is typically only able to withstand about 33 Newton-meters of torque — and a single baseball pitch can amount to as much as 64 Newton-meters of valgus force.

As you can imagine, with the amount of repetitive overhead throwing that pitchers need, the MUCL is placed under large amounts of strain and valgus stress, which is the primary cause for a ruptured or torn ligament.

Tommy John surgery utilizes a tendon graft to replace the MUCL tissues. Success rates for MUCL reconstruction vary depending on technique, although recent studies have indicated a range of 80-95% success in return to play.

That being said, there’s also a complication rate of 8-10% during the procedure, and the recovery timeline to return to sport averages around 20 months. So, while there is a high chance for success for reconstruction, the aftermath can still have lasting effects on an athlete’s return to play and confidence in attaining the same level of performance.

What are the Risk Factors for UCL Tears?

Although we know that baseball players (and pitchers, especially) are at high risk for rupturing the MUCL, there are other, more nuanced factors that increase a player’s injury risk. Here are the 3 most common risk factors that lead to excessive force at the MUCL…

The Carrying Angle of the Elbow

Simply put, the “carrying angle” of your elbow measures how far out your arms are from your body when you naturally hold them at your sides with your palms facing forward.

On average, males will have about 5-10 degrees of distance from their forearms to their sides, whereas females will have about 13-15 degrees.

Although this seems like a minor measurement, it can make all the difference in your injury risk! The larger your carrying angle, the more valgus stress is placed on the elbow, which of course worsens the amount of stress on the joint during overhead throwing.

Many instances of high carrying angles are caused by bony alignments in adults (which ultimately can’t be modified), but it can also be brought on by increased laxity in the ligament or restrictions in the soft tissue surrounding the joint.

Pitch Count and Speed

Because repetitive throwing motions can cause microtraumas in the MUCL, the frequency and intensity of pitching can understandably affect your injury risk.

However, interestingly enough, increased pitch count doesn’t affect all players — research has found that this is predominantly a risk factor for younger baseball players. When younger athletes have high pitch counts, more innings pitched per game, or throwing practice for more than 8 months out of the year, they present an increased risk for elbow injuries.

But when it comes to elite level baseball pitchers, there’s less correlation between high pitching volume and elbow injury. Instead, one study found that elite players had a larger correlation between elbow injury and the velocity of pitching, rather than the amount of throwing.

Interestingly enough, the rate of injury wasn’t affected by the type of pitch. Regardless of how the ball was thrown, players sustained elbow injury in relation to high pitching velocity (which makes sense; the faster you pitch, the more strain your muscles and ligaments have to endure to build greater force).

Improper Pitching Biomechanics

And finally, we have the most complex risk factor for Tommy John surgery: poor biomechanics.

As you likely already know, proper pitching form is no easy task to master. There are a lot of moving pieces (literally), and the biomechanics can get pretty granular. After all, throwing requires specific movement at the trunk, shoulder, AND elbow, and there are six phases in one pitching motion.

Understandably, there’s plenty of room for error that could increase stress on the medial elbow and increase the chances of ligament injury.

Due to the complex nature of throwing mechanics, we’re going to save the biomechanical specifics for our next blog of the series. But, in the meantime, keep reading up about Tommy John surgery — although it’s necessitated by debilitating injury, it’s a fascinating process! (And stay tuned for our upcoming blog about pitching biomechanics and injury prevention!)

By Dr. James Liaw DPT CSCS SCS

Dr. Liaw specializes in working with athletes of all calibers, spending the early part of his career in a sports medicine residency and creating sport-specific rehabilitation programs. He later went on to serve as the team PT for the Idaho Steelheads (Boise’s minor league hockey team) and furthered his expertise in sports rehab, injury prevention, preparticipation screenings, and return-to-sport testing. During his free time, he enjoys climbing (both in the gym and outdoors), watching sports (49er faithful), mountain biking, snowboarding, learning new things, and eating good food.

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