Rehabilitating Tommy John Surgeries – Non-Standard Cases

Most cases of ulnar collateral ligament replacement (UCLr, or “Tommy John” surgery) follow a fairly standard throwing program and rehabilitation program. A sample throwing program once cleared to throw looks something like this:

Sample TJ Throwing Program

However, not all athletes respond to such a conservative program. It is also our opinion that touching a baseball should show up significantly later in the “throwing program” than what most PT and MDs recommend. For example, in weeks 1-3, many of our athletes will never touch a baseball and instead will do primarily negative/reverse throwing with Driveline PlyoCare Balls. Furthermore, they will generally NOT throw balls at the regulation weight – 5 oz. Their first throws will often be with an overload ball (8 oz) at very low intensities to “feel” the motor patterns they should be building. Touching a baseball and throwing it brings back hundreds of thousands of reps and feelings from throwing a baseball, which is hard to change. This psychological connection is meaningful and is often overlooked!

Here’s an example of the intent with an 8 oz. ball for the first week of throwing:

Specific Case – Ex-Pro Tennis Player

Jeff is a converted ex-pro tennis player (now pitcher) who had an unsuccessful rehabilitation from UCLr. While the surgery left his elbow stable, he lost gross amounts of shoulder external rotation, has nagging biceps irritation, and lost massive ball velocity, going from 88-90 to 78-81 despite completing a full throwing program similar to the one above in this post.

He felt rehab was not specific enough to traits that were not common in baseball pitchers, like increased hypertrophy of the upper arm that is seen in tennis players.

In cases where pitchers who can still throw with significant ball velocity (80+ MPH) and have serious loss of static external rotation (ER), we will do manual therapy to stretch them into that position. While this is usually NOT RECOMMENDED (I cannot stress this enough), research does support the idea that a large deficit of dynamic ER vs. static ER could be linked with medial elbow pain/injury:

ER and MER in throwing, and the ratio of the MER to the ER were compared between high school baseball players with and without a history of throwing elbow injuries. The elbow-injured group demonstrated significantly greater ratio of MER to ER than that in the control group. This finding suggests that the throwing mechanics that is characterized by great MER in relation to ER could be associated with medial elbow pain in high school baseball players. (The Role of Shoulder Maximum External Rotation During Throwing for Elbow Injury Prevention in Baseball Players, Miyashita et. al. JSSM 2008)

Here’s a day in the life of Jeff rehabbing at Driveline Baseball in his new program. Not shown is the movement prep and PlyoCare throwing circuit he uses to “warm up” prior to flat ground throwing:

How Muscles Work and Protect a Pitcher’s Elbow

Let’s talk about muscles. Muscles are the motors of the body. They are the components that generate movement. They can also absorb dangerous forces to protect more vulnerable tissues, like ligaments, and this is especially important for baseball pitchers.

Before I dive in, if you missed part one or two of the three part introduction to my views on the biomechanics of pitching, here’s a short summary.

I disagree with using the total elbow load as an approximation of the load on the ulnar collateral ligament (UCL). Therefore, I believe using the total load as an indicator of elbow injury risk is flawed.

One of the biggest drawbacks to using the total joint load is that it provides no information about the underlying muscles. This is why I account for the muscles, in addition to the ligaments and bones, when I analyze the biomechanics of a pitching motion using computational modeling techniques.

Now that you’re caught up, let’s focus on the muscles.

A muscle originates on one part of the body, at a location called its origin. It then crosses one or more joints and inserts on a different body part, at a location called its insertion. The body part of origin is typically the larger body part. When a muscle is excited by the nervous system, it contracts and attempts to shorten. In doing so, it exerts a pulling force at the origin and insertion. The pulling force causes the connected body parts to attempt to rotate about the encompassed joints in directions that shorten the muscle.

One of the most vital properties of muscle is the force-velocity property. Due to this property, the pulling force exerted by a muscle depends on the speed with which it is changing length. When a muscle is contracting and shortening quickly, it cannot generate much pulling force. This is called a concentric contraction. In contrast, when a muscle is lengthening but also excited by the nervous system (i.e. attempting to contract), it can generate a lot of pulling force. This is called an eccentric contraction. A stationary contraction, when the muscle is not changing length, is called an isometric contraction.

Force-Velocity Curve

Figure from Millard et al. 2013 [1]. The vertical axis shows the multiplier by which the force exerted by a muscle is decreased or increased depending on contraction type.

An eccentric contraction occurs when an outside force is applied to a muscle that is greater than the maximum internal pulling force it can generate in its current condition. The maximum internal pulling force is governed by the muscle’s structure, its current level of excitation from the nervous system, and several other physiological factors. As seen in the figure, a muscle can actually produce more force during lengthening than it can when it is either shortening or stationary.

(A great reference for the previous paragraphs is this textbook from Dr. Rick Lieber [2].)

Our bodies often use eccentric contractions to decelerate body parts after periods of rapid acceleration, which is exactly what happens in the forearm during pitching.

Other examples of concentric, isometric, and eccentric contractions can be seen when a person is doing pull-ups. When the person is pulling up to the bar, his or her biceps muscles are concentrically contracting. When the person is holding at a steady position, the muscles are isometrically contracting. And finally, when the person is slowly lowering himself or herself down from the bar and controlling the descent, the biceps are eccentrically contracting.

Biceps

Understanding muscle force production under all conditions is critical to analyzing and improving pitching mechanics, especially at the elbow. All of the muscles that cross this joint make essential contributions using all different types of muscle contractions.

And in baseball pitching circles, one group of elbow muscles gets more attention than the rest: the flexor-pronator muscles.

This muscle group gets more attention with good reason – studies have shown that muscle contractions in this group can relieve loading on the UCL [3-5]. Lesser loading on the UCL likely reduces the risk for a UCL tear and Tommy John surgery. Accordingly, injuries in this muscle group likely increase UCL loading during pitching and therefore may increase UCL injury risk.

The flexor-pronator muscles are able to protect the UCL because they reside in similar locations to the UCL on the body [6]. Both the muscles and the ligament originate on the inside (the medial side) of the bone of the upper arm (the humerus). Thus, when the muscles are contracting, they are likely absorbing force that would otherwise be damaging the UCL.

The UCL originates on the humerus and then simply crosses the elbow joint to insert on the medial bone of the forearm (the ulna). However, the paths of the flexor-pronator muscles from origin to insertion are far more complex. In this muscle group, there are four muscles (FDS, FCR, FCU, and PT) that collectively cross the elbow, forearm, wrist, and even finger joints.

Try placing your left hand on the inside of your right elbow and then making a tight fist with your right hand. You will feel the movement of the tendons of your flexor-pronator muscle group with your left hand when you squeeze your right hand.

Because of the complexity of the flexor-pronator muscle paths, we cannot look at one arm joint or posture in isolation when we’re trying to analyze a pitcher’s elbow injury risk. Motions at the elbow, forearm, wrist, and even fingers all impact the outputs of the flexor-pronator muscles and their collective ability to protect the UCL. Depending on a pitcher’s mechanics and nervous system excitation patterns, the muscles can either be contracting concentrically, eccentrically, or even isometrically at any point in the pitching motion.

Therefore, an understanding of how a pitcher’s muscles are acting during his specific motion is imperative to assessing risk and prescribing effective training regimens.

This is exactly what I do in my biomechanical analysis approach [7]. I use a computational musculoskeletal model of the human body to compute and describe muscle actions, and then assess injury risk based on the results. From looking at the muscle actions, strategies can be devised that target the most important muscles in the most effective ways possible.

In the high school, college, and professional pitching motions I’ve analyzed, I’ve observed both concentric and eccentric contraction patterns in the flexor-pronator muscles during time periods of increased UCL injury risk. Different contraction patterns require different training techniques.

I do not agree with forcing a pitcher to conform to exact “ideal” mechanics. I do believe there should be mechanical guidelines, but I think it is essential to let a pitcher’s individual anatomy and muscle physiology guide his precise mechanical approach. Look at Greg Maddux. Look at Randy Johnson. Look at Pedro Martinez. Pitching success comes in all shapes and sizes.

Dr. James H. Buffi has a degree in mechanical engineering from the University of Notre Dame and a PhD in biomedical engineering from Northwestern University. His doctoral dissertation was called, “Using Biomechanical Modeling and Simulation to Calculate Potential Muscle Contributions to the Elbow Varus Moment during Baseball Pitching.”  He has also been a visiting scholar in the National Center for Simulation in Rehabilitation Research at Stanford University as well as a visiting researcher at Massachusetts General Hospital. You can follow @jameshbuffi on twitter.

References:

  1. Millard, M., et al., Flexing Computational Muscle: Modeling and Simulation of Musculotendon Dynamics. Journal of Biomechanical Engineering-Transactions of the Asme, 2013. 135(2).
  2. Lieber, R.L., Skeletal muscle structure, function & plasticity : the physiological basis of rehabilitation. 3rd ed. 2009, Philadelphia: Lippincott Williams & Wilkins.
  3. Lin, F., et al., Muscle contribution to elbow joint valgus stability. Journal of Shoulder and Elbow Surgery, 2007. 16(6): p. 795-802.
  4. Seiber, K., et al., The role of the elbow musculature, forearm rotation, and elbow flexion in elbow stability: an in vitro study. Journal of Shoulder and Elbow Surgery, 2009. 18(2): p. 260-8.
  5. Udall, J.H., et al., Effects of flexor-pronator muscle loading on valgus stability of the elbow with an intact, stretched, and resected medial ulnar collateral ligament. Journal of Shoulder and Elbow Surgery, 2009. 18(5): p. 773-778.
  6. Davidson, P.A., et al., Functional-Anatomy of the Flexor Pronator Muscle Group in Relation to the Medial Collateral Ligament of the Elbow. American Journal of Sports Medicine, 1995. 23(2): p. 245-250.
  7. Buffi, J.H., et al., Computing Muscle, Ligament, and Osseous Contributions to the Elbow Varus Moment During Baseball Pitching. Ann Biomed Eng, 2014.

A More Forward Approach to Understanding Pitching Biomechanics

This is part two of three of the initial guest posts by Dr. James Buffi. Part one was titled Challenges with Typical Biomechanical Analyses of Pitching.

It is impossible to figure out if a specific player scored a run in a baseball game just by looking at the final box score. This is essentially what typical biomechanical analyses of pitching try to do. They attempt to infer the underlying outcome for the UCL from macroscopic surface-level observations of net elbow loading.

As stated in my previous post, the total elbow load is not nearly enough information to determine the underlying ligament load.

Most of these typical biomechanical analyses can be classified as inverse dynamic analyses. The word “inverse” refers to the order in which calculations are performed relative to the way the body actually creates motion. In an inverse dynamic analysis, the total joint loads are recorded and calculated first. The loads on individual joint structures and muscles are then computed second. This directly contrasts the way the human body actually creates motion.

In the human body, the muscles are generally activated first by the brain. A motion then occurs second, as a result of the activation. When an analysis of a motion is performed by working “forward” from neural command, to muscle output, to joint loading, and then to the motion, it is called a forward dynamic analysis. In a forward analysis, a motion is analyzed in the same way the body creates it, as opposed to the inverse approach, in which the analysis starts with the end result and works backwards.

Forward Dynamics

Referring back to the example I used in my first post, let’s again consider the situation in which two teams of 15 people are playing a game of tug-of-war. To perform an inverse analysis of the game, the total load on the rope is measured first, and then the loads supported by individual players are estimated second from the total rope load.

In contrast, to perform a forward analysis of tug-of-war, one would start by determining the loads supported by individual players, and then calculate the total rope load that results. The forward analysis better represents the observed process. It does not require approximating a method for working backwards from the load on the rope to the underlying loads supported by specific individuals.

When I perform a biomechanical analysis of a pitcher, I use a more forward approach. I go straight to the muscles and ligaments. To be clear, I do not perform a forward dynamic analysis in the purest sense, because my approach still begins with the recording of the pitching motion rather than the neural command. However, I do not calculate the total joint loading as an intermediate step. I compute the actions of the muscles and ligaments directly from the pitcher’s motion using knowledge of musculoskeletal anatomy and neural activation patterns. I am able to accomplish this with computational, physics-based, musculoskeletal-modeling techniques.

The development of my computational approach began while I was working toward my PhD. I used a computer model of the human body and a well-defined algorithm [1] to compute muscle forces that generated a recorded pitching motion. The algorithm included an embedded forward dynamic analysis. The specific computer model I used was developed from bone, muscle, and ligament geometry measurements taken in cadavers, as well as strength measurements taken in living subjects [2, 3].

Pitching Timeline

In 2014, I published an academic article using my modeling approach [4]. In this study, titled “Computing Muscle, Ligament, and Osseous Contributions to the Elbow Varus Moment During Baseball Pitching,” I created a computer simulation of a high school pitcher’s throwing motion. I then used the simulation to investigate how individual muscles can affect UCL loading. I also investigated how changes in muscle output can either relieve or exacerbate the load on the UCL.

My simulation results supported what many people have postulated over the years: muscles have the ability to substantially influence the load on the UCL [5-7]. As expected, my simulation results showed that the forearm flexor-pronator muscles have the capacity to generate considerable protective elbow forces. Surprisingly, due to the subject’s specific posture at the time of maximum elbow loading in his pitching motion, I also found that the triceps muscles were able to protect the subject’s UCL. This may not hold for every pitcher, but it is definitely worth exploring.

Additionally, when I increased the outputs of all the subject’s muscles in a simulation (as one could theoretically do using a well-defined training regimen), I was able to eliminate the simulated load on the subject’s modeled UCL.

This is an awesome result. It implies that pitchers can protect their elbows through muscle training. It implies that changes to throwing mechanics are not always necessary for injury prevention. However, it is important to understand that it only occurred in one simulation of one motion with certain muscles isolated. More work is needed before this result can be applied in the training room or on the practice field. The potential to get this work done is just one of the many reasons why I am excited to work with Kyle Boddy here at Driveline. He believes in using scientific evidence to support advanced training techniques.

The most important outcome of my 2014 study, which became the crux of my doctoral dissertation, is that I developed a framework for subject-specific muscle-driven analyses of pitching. This means that I can now record a specific pitcher’s throwing motion and give him a legitimate analysis of what is going on with his muscles and ligaments, in a way that has never been done before.

In fact, this more forward approach is already generating new and exciting research outcomes. Using this approach, I have observed notable differences between the muscle and ligament actions of previously injured and non-injured pitchers (which I hope to publish within the next year). If I am able to develop tests that detect specific differences such as these, there is great potential to identify injury-prone pitchers before they get injured. Furthermore, there is the potential to design training programs that compensate for observed differences and protect vulnerable muscles and ligaments.

The current state of baseball speaks volumes. Elbow injury rates are so severe that teams feel like they are running out of options. Certain teams are even seriously considering six-man rotations. Now I think it’s time for baseball to embrace a more forward approach to pitching injury prevention.

Dr. James H. Buffi has a degree in mechanical engineering from the University of Notre Dame and a PhD in biomedical engineering from Northwestern University. His doctoral dissertation was called, “Using Biomechanical Modeling and Simulation to Calculate Potential Muscle Contributions to the Elbow Varus Moment during Baseball Pitching.”  He has also been a visiting scholar in the National Center for Simulation in Rehabilitation Research at Stanford University as well as a visiting researcher at Massachusetts General Hospital. You can follow @jameshbuffi on twitter.

References:

  1. Thelen, D.G., F.C. Anderson, and S.L. Delp, Generating dynamic simulations of movement using computed muscle control. Journal of Biomechanics, 2003. 36(3): p. 321-328.
  2. Holzbaur, K.R.S., et al., Moment-generating capacity of upper limb muscles in healthy adults. Journal of Biomechanics, 2007. 40(11): p. 2442-2449.
  3. Holzbaur, K.R.S., et al., Upper limb muscle volumes in adult subjects. Journal of Biomechanics, 2007. 40(4): p. 742-749.
  4. Buffi, J.H., et al., Computing Muscle, Ligament, and Osseous Contributions to the Elbow Varus Moment During Baseball Pitching. Ann Biomed Eng, 2014.
  5. Lin, F., et al., Muscle contribution to elbow joint valgus stability. Journal of Shoulder and Elbow Surgery, 2007. 16(6): p. 795-802.
  6. Seiber, K., et al., The role of the elbow musculature, forearm rotation, and elbow flexion in elbow stability: an in vitro study. Journal of Shoulder and Elbow Surgery, 2009. 18(2): p. 260-8.
  7. Udall, J.H., et al., Effects of flexor-pronator muscle loading on valgus stability of the elbow with an intact, stretched, and resected medial ulnar collateral ligament. Journal of Shoulder and Elbow Surgery, 2009. 18(5): p. 773-778.

Challenges with Typical Biomechanical Analyses of Pitching

This is a guest post from Dr. James H. Buffi, Ph.D. in Biomedical Engineering.

It is impossible to overstate how excited I am to have Dr. Buffi contribute to our blog in what will be the first article in a three-part series on the biomechanics of pitching. In 2014, Dr. Buffi had a paper published title Computing Muscle, Ligament, and Osseous Contributions to the Elbow Varus Moment During Baseball Pitching (pubmed) which absolutely stunned me with the new methodology he had taken. Prior to that, Dr. Buffi had presented a conference paper titled Effect of Forearm Posture on the Elbow Varus Torque Generated by the Flexor Pronator Muscles: Implications for the Ulnar Collateral Ligament (pdf) which has been quoted on this blog and on my Twitter feed many times.

Dr. Buffi reached out to me not long ago and we had a great conversation where we discussed where we thought the future of baseball training would be going and where it needed to improve to make serious dents on the rash of elbow injuries that all pitchers are dealing with, from Little League to MLB. It is my pleasure to provide a platform for Dr. Buffi to present his views and to announce that he will be working with Driveline Baseball in the future in some capacity!

——

Challenges with Typical Biomechanical Analyses of Pitching

Have we found the Tommy John solution?

Is this the sleeve that could save baseball?

These are the questions being posed by baseball enthusiasts as the company Motus Global markets a compression sleeve that pitchers can wear to monitor and manage the workloads on their pitching elbows.

I have played baseball since I first learned to walk. I am a fanatic about the sport in every sense of the word. I also have a PhD in biomedical engineering and I can tell you that the Motus sleeve will probably not save baseball from the epidemic of elbow ulnar collateral ligament (UCL) tears that lead to Tommy John surgeries.

To be clear, I am in no way saying that the Motus sleeve is without value. From what I know, I actually think it is a solid first step. The Motus sleeve takes baseball biomechanical analyses out of the laboratory and onto the playing field in live game situations, and it provides a method for tracking your workouts and monitoring your mechanics. These are definitely good things.

However, I do have some serious questions about the claim that the Motus sleeve monitors the load on your UCL. Moreover, there are systematic challenges with the biomechanical analyses being utilized by most institutions, including the American Sports Medicine Institute (ASMI), that try to prevent UCL injuries by monitoring total elbow loading or total elbow stress.

All biomechanical analyses of pitching begin the same way. First, the pitching motion, and specifically the acceleration of the elbow, is recorded in three dimensions. This is often done using markers and cameras, or it is done using small inertial measurement units similar to the components that allow smart phones to detect landscape versus portrait mode. The Motus sleeve uses the latter approach.

After recording the motion of the pitcher’s elbow, most institutions (including Motus and ASMI) use an inverse dynamic process to then calculate the total elbow load (or stress) in the form of a joint torque. Torque is simply force that causes rotation. Calculating this total load is fairly straight forward, as Sir Isaac Newtown told us that force equals mass times acceleration. Sparing a few details, this means that the total elbow load is equal to the mass of the forearm and hand multiplied by its rotational acceleration.

Now we have come to the gaping hole in this process… how do we calculate the specific load on the UCL from the total elbow load?

Forearm

The UCL is basically a tiny band that connects the humerus to the ulna, and as far as I know, it is actually impossible with existing methodologies to accurately determine UCL loading when only the total elbow load is considered. This ligament is only a few centimeters in size and it is in close proximity to many muscles and other soft tissue. It is loaded (i.e. it feels a force) when it is stretched, similar to an elastic band. The image below shows the musculature of the left forearm. The UCL is hidden beneath the highlighted muscle near the elbow.

There are more than 10 muscles that cross the elbow [1], and when we only consider the total elbow load, we really have no way of calculating how any of these muscles are individually affecting the load on the UCL during a pitch. Scientists have used experiments in cadavers to show that the muscles on the inside of the elbow (the medial side) can relieve a load on the UCL [2-4]. The problem is these experiments cannot yet be replicated in living subjects.

Additionally, the bones of the elbow also provide substantial stability. Back in 1983, Dr. Morrey and Dr. An reported that just the bones and the joint capsule can support upwards of 40% of an applied elbow load [5]. However, this study was also completed in cadavers and muscles were not considered because the cadavers were dissected.

Furthermore, I published an academic article in 2014 that showed via simulation that the load on the UCL can range from catastrophic to nonexistent depending on the contributions from the muscles and bones [6].

Therefore, it remains unclear how the total elbow load relates to the specific load on the UCL. For a given elbow load, the UCL load could be really high if the muscles and bones are weak, or it could be really low if the muscles and bones are strong.

Consider the following thought experiment: If you have two teams of 15 people playing tug-of-war and the only thing you can measure is the total load on the rope, are you able to determine the specific load supported by any individual person on either team?

This is an impossible task.

Now the question we must ask is: can we develop effective training plans using the measurements of elbow loading provided by the Motus sleeve and other typical biomechanical analyses?

Without more information, the answer is likely no.

If a pitcher has a higher total elbow load, but also capable muscles and bones that protect his UCL, he may be able to push himself more in his throwing program when the typical advice would be to scale back. Muscles get stronger by overloading, not underloading. If a pitcher has a lower total elbow load, but also much less capable muscles and bones, he may actually be at a higher risk for UCL injury than one would expect. In this case, the pitcher may need to reduce his workload until he strengthens his muscles, while the typical advice would be to do the opposite and ramp up throwing.

The bottom line is that the total elbow load or the total elbow stress is a very poor predictor of UCL injury risk. In fact, excessively monitoring a pitcher’s total elbow load could actually increase his injury risk. If a pitcher were to scale his workload back too much in response to elevated elbow loading, he could actually weaken his muscles and therefore increase his risk for a UCL tear and a Tommy John surgery. This means that improper use of the Motus sleeve could actually be very dangerous for baseball.

In my own biomechanical analyses of pitching, I avoid the pitfalls mentioned above by monitoring the loads on individual muscles and ligaments. I accomplish this using advanced numerical methods and an anatomically-based computer model of the human body. This approach will enable targeted training of specific muscles and more accurate assessments of UCL vulnerability.

There may not be a solution to the Tommy John epidemic just yet, but I am confident we can change this very soon with the right scientific approach.

Dr. James H. Buffi has a degree in mechanical engineering from the University of Notre Dame and a PhD in biomedical engineering from Northwestern University. His doctoral dissertation was called, “Using Biomechanical Modeling and Simulation to Calculate Potential Muscle Contributions to the Elbow Varus Moment during Baseball Pitching.”  He has also been a visiting scholar in the National Center for Simulation in Rehabilitation Research at Stanford University as well as a visiting researcher at Massachusetts General Hospital.

References:

  1. Holzbaur, K.R.S., et al., Moment-generating capacity of upper limb muscles in healthy adults. Journal of Biomechanics, 2007. 40(11): p. 2442-2449.
  2. Lin, F., et al., Muscle contribution to elbow joint valgus stability. Journal of Shoulder and Elbow Surgery, 2007. 16(6): p. 795-802.
  3. Seiber, K., et al., The role of the elbow musculature, forearm rotation, and elbow flexion in elbow stability: an in vitro study. Journal of Shoulder and Elbow Surgery, 2009. 18(2): p. 260-8.
  4. Udall, J.H., et al., Effects of flexor-pronator muscle loading on valgus stability of the elbow with an intact, stretched, and resected medial ulnar collateral ligament. Journal of Shoulder and Elbow Surgery, 2009. 18(5): p. 773-778.
  5. Morrey, B.F. and K.N. An, Articular and Ligamentous Contributions to the Stability of the Elbow Joint. American Journal of Sports Medicine, 1983. 11(5): p. 315-319.
  6. Buffi, J.H., et al., Computing Muscle, Ligament, and Osseous Contributions to the Elbow Varus Moment During Baseball Pitching. Ann Biomed Eng, 2014.
By |February 18th, 2015|Injuries, Research|0 Comments