UCL Sprain And Outcomes

Ulnar collateral ligament (UCL) sprains are a common injury among athletes, especially those who participate in throwing sports like baseball. If you’re an athlete who has experienced a UCL sprain, you may be familiar with the term Tommy John surgery. This procedure has become synonymous with UCL injuries, but what is it, and how does it help athletes recover? In this blog post, we’ll explore UCL sprains, Tommy John surgery, and what athletes can expect during the recovery process. A similar injury in youth athletes is little league elbow. Learn more about that here.

UCL Anatomy

The UCL provides stability to the medial elbow against valgus stress. It works very similarly to the MCL of the knee. It originates on the distal end of the humerus (the upper arm bone) and attaches to the ulna (the pinky side forearm bone).

Specifically it attaches to the medial epicondyle. This is a shared attachment point to the wrist flexor bundle which will be more relevant later on in this post. It consists of 3 different bands; the anterior (strongest), the posterior and the transverse.

ucl anatomy

How Does The UCL Get Sprained?

Damage to the UCL occurs almost exclusively from valgus force to the elbow. It can happen via some hyperextension injuries but we’ll briefly touch on that as a UCL injury in a non thrower is a non issue. This valgus force can occur when the hand is fixed on the ground and external force is applied to the outside of the elbow.

valgus force causing a UCL sprain

The primary way a UCL is sprained is as a result of throwing a baseball. The force exerted on the medial elbow every time a baseball is thrown exceeds the tensile capacity of the UCL, yet it doesn’t tear every throw. This is because the wrist flexors provide additional stability to the elbow and absorb most of the force.

In fact, read this study (link) on how having weaker wrist flexors leads to a higher risk of UCL sprain. This study will tie directly into the prevention of a UCL sprain

How Can Your Prevent A UCL Sprain?

First off, no injury can be fully prevented, but the risk can be reduced. Since the wrist flexors act as secondary stabilizers of the medial elbow, these will be the focus.

Grip strength is one of the best objective measurements we can use regarding UCL sprain prevention. In the MLB, we would assess grip strength as a pre season baseline. Throughout the course of the season, those measurements would be retaken.

If there was a decrease in strength that was statistically significant, interventions would be done to improve grip strength. To see what the beginning of a good grip strength program looks like, click here. Yes this is a program for Golfer’s Elbow, but remember, its the same muscle group we need to adress.

Diagnosis Of A UCL Sprain

The gold standard for a UCL sprain is going to be an MRI with contrast. What this means is that a dye is injected directly into the UCL. When the image is taken, the dye can be seen leaking out through the damaged UCL.

There are a few clinical exams that can be done but they are far less reliable. We’ll look at two below. Textbooks will tell you a positive test is pain and laxity.

However, true laxity cannot be found in the elbow even with a full blown UCL rupture. There can only be 1mm of laxity assessed at the elbow. Human hands do not have that much sensitivity to feel that.

As a result, a clinical exam will look for pain in the test, and if positive, refer out for an MRI.

  1. Elbow Valgus Stress Test

2. Modified Milking Maneuver

UCL Rehab And Tommy John Surgery

This is where extreme nuance comes into the equation. There is not a single black and white answer here.

Conservative Rehab

We’ll get non throwers out of the way here first, If you are a non throwing athlete, you will never need Tommy John surgery as you can get the secondary elbow stabilizers strong enough so conservative rehab is always the answer here. A rehab program that would work can be found below

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    Here’s where the conversation gets difficult. In the event that the UCL is not fully torn (grade 1 or 2) you can have success with conservative rehab.

    However, there is no guarantee this will work and you will need several months of rehab plus a return to throwing program. The problem is that this can take up to 6 months.

    The risk a pitcher would run is taking 6 months to rehab, the rehab not working and then needing surgery. Tommy John surgery can take up to 12-18 months in and of itself.

    So now you add 6 more months and you could be looking at almost 2 years before a return to competition which is not even a guarantee that pre surgery levels are ever achieved.

    The rehab program embedded above is a good starting point for UCL sprain rehab.


    Tommy John surgery is the default option for UCL sprains in throwing athletes. It has anywhere from an 80-95% return to play rate. However, there is a 20% risk that pre surgery competitive levels are never restored.

    In short, Tommy John surgery works by removing a tendon from the forearm (Palmaris Longus). However, a good chunk of the population does not have this tendon (30%). In this case, they usually remove a toe extensor tendon and then graft that to where the UCL once was.

    In summary, a UCL sprain can be a complete non issue in a non throwing athlete. However, it can range all the way up to potentially a career ending injury if it occurs in a throwing athlete.