A 2011 study published in The American Journal of Sports Medicine examined MRI findings in 23 uninjured high school pitchers who had no pain, no functional limitations, and no history of elbow surgery. Researchers Hurd and colleagues recruited these athletes specifically because they were healthy, they wanted to establish what a "normal" throwing elbow looked like on imaging in this population. What they found challenges one of the most fundamental assumptions in sports medicine, that abnormal-looking structures on an MRI represent pathology. Nearly 70 percent of these completely asymptomatic pitchers showed structural changes that would typically be classified as abnormal. Sixty-five percent had thickening of the UCL's anterior band, 61 percent showed posteromedial subchondral sclerosis, 35 percent had developed osteophytes at the olecranon, and 43 percent exhibited multiple abnormal findings. These weren't subtle changes that required expert interpretation to detect, these were clear structural adaptations that, in the wrong hands, could easily be mistaken for injury. The study highlights a critical reality, without extensive clinical experience evaluating throwing athletes, even trained radiologists and orthopedists can misinterpret adaptive tissue remodeling as pathology, leading to overdiagnosis, unnecessary rest, and potentially unwarranted surgical intervention.

What the Study Found

The researchers performed MRI scans on both elbows of each pitcher, allowing them to compare the throwing arm to the non-throwing arm and establish what changes were specific to the repetitive loading of pitching. All participants had closed growth plates, meaning they were skeletally mature, which ruled out the possibility that what they were seeing was simply developmental variation in younger athletes. The imaging revealed consistent patterns of structural change across the group, patterns that mirrored what had been documented in adult professional pitchers but were now showing up in high school athletes who had never experienced elbow pain or dysfunction.

The most common finding was thickening of the anterior band of the ulnar collateral ligament, present in 65 percent of the throwing arms. The UCL is the primary restraint against valgus stress at the elbow during throwing, and it experiences massive loads with every pitch. Over time, the ligament responds to that stress by laying down additional collagen fibers and increasing its cross-sectional area. This thickening isn't weakness, it's reinforcement. The ligament is adapting to the demands being placed on it, building structural capacity to handle repetitive high-magnitude loading. But on an MRI, especially if the radiologist isn't familiar with throwing athletes, thickened ligament tissue can look concerning. It deviates from what you'd see in a non-throwing population, and without context, it's easy to interpret deviation as damage.

Sixty-one percent of the pitchers showed posteromedial subchondral sclerosis of the ulnotrochlear articulation, which is a fancy way of saying the bone at the back inner part of the elbow joint had become denser and more compact. This happens because the olecranon, the bony tip of the ulna, repeatedly impacts the olecranon fossa during the deceleration phase of throwing. That repetitive contact creates compressive forces that stimulate bone remodeling. The bone responds by becoming thicker and harder in the areas experiencing the most stress, which is exactly what bone is supposed to do when subjected to repetitive load. But again, if you're looking at an MRI without understanding the mechanical demands of pitching, sclerotic bone can raise red flags. It suggests chronic stress, and in many contexts, chronic stress is a precursor to injury.

Thirty-five percent of the athletes had developed posteromedial osteophytes, small bony projections at the olecranon. These form as a result of traction forces where soft tissues attach to bone, or as the body's attempt to increase surface area in regions experiencing repetitive impaction. Osteophytes often get labeled as degenerative changes, which carries a negative connotation, but in young, asymptomatic athletes, they may simply represent adaptive remodeling in response to the unique stresses of overhead throwing. Seventeen percent showed chondromalacia, softening of the cartilage in the same region, which is typically associated with wear and tear. In isolation, that finding might suggest early joint degeneration, but when it appears in an athlete with no symptoms and full function, the interpretation has to change.

What makes these findings particularly important is that 43 percent of the pitchers exhibited multiple abnormalities. This wasn't a situation where one or two athletes had an isolated structural quirk, nearly half the group showed patterns of change that, if you didn't know they were pain-free and performing at a high level, you might interpret as evidence of significant elbow pathology. The researchers noted that no signal changes were observed in the radial collateral ligament or the ulnar nerve, suggesting that the adaptations were specific to the structures experiencing the highest mechanical loads during throwing.

Why This Information Is Important

To be honest, this reminds me of every conversation I've had with athletes who get an MRI for an unrelated reason, maybe they're in a pre-participation physical or they're being evaluated for something minor, and the imaging report comes back listing all these "abnormalities." The athlete panics, the parents panic, and suddenly a kid who was throwing pain-free is being told he needs to shut down for six weeks because his UCL looks thickened or there's bone remodeling at the olecranon. But the athlete wasn't broken before the MRI, and the MRI didn't reveal an injury, it revealed adaptation. The problem is that adaptation and pathology can look remarkably similar on imaging if you don't have the clinical context to distinguish between them.

This issue extends far beyond high school pitchers. A 2024 study using microscopic MRI examined 426 baseball players, 158 asymptomatic and 268 symptomatic, and found something stunning. Approximately 30 percent of the asymptomatic players had high-grade UCL damage, rated as grade III or IV tears on the standard MRI classification system. These weren't minor changes, these were structural disruptions that would typically be considered surgical candidates. But here's the kicker, the prevalence of high-grade tears was nearly identical between the asymptomatic and symptomatic groups, meaning the imaging findings didn't correlate with whether the athlete was in pain or functionally limited. In fact, there was no significant difference in UCL grades between the two groups at all. The thing that did correlate with symptoms was bone marrow edema in the sublime tubercle, a subtle sign that's easy to miss if you're focused solely on ligament integrity. This tells us that what we think matters on an MRI, the size and grade of a tear, often doesn't predict clinical presentation, while the things we might overlook, like localized bone stress, might be far more relevant.

Another study analyzed 245 pre-draft elbow MRIs from asymptomatic Major League Baseball pitchers and found that 70 percent showed abnormalities. Twenty-seven percent had UCL tears, with 24 percent showing partial tears and 3 percent showing full-thickness tears. Twenty percent had UCL thickening, 36 percent had periligamentous edema, and 27 percent showed stress reactions in the bone. These were elite athletes at the peak of their careers, about to be drafted into professional baseball, and the majority of them had imaging findings that would be classified as pathological in a textbook. Yet none of them were experiencing symptoms that would prevent them from playing. The study reinforced the idea that structural changes visible on imaging must be interpreted within the context of an athlete's clinical presentation, not in isolation.

Research on elite Dominican baseball prospects adds another layer to this discussion. A study of 75 athletes selected for an MLB scouting event found that 93.9 percent of pitchers had rotator cuff pathology, including tendinosis in 78.8 percent and partial tears in 15.2 percent. Seventy-five point eight percent had labral tears, 81.8 percent had UCL abnormalities, and 69.7 percent had olecranon osteophytes. These numbers are staggering, but here's the context, none of the athletes reported symptoms. They weren't complaining of pain, they hadn't sought medical treatment, and they were performing well enough to be invited to an elite showcase event. The researchers appropriately framed the findings as potentially representing sport-specific adaptations, expected changes that occur with chronic repetitive use in a highly trained population. But the risk is clear, if you take those MRIs out of context and hand them to a clinician unfamiliar with throwing athletes, you could easily conclude that nearly every athlete in the cohort is injured and needs intervention.

The disconnect between structure and symptoms shows up in post-surgical populations as well. A study tracking 91 MLB pitchers returning from UCL reconstruction found that while velocity and spin rate returned in the first year after surgery, fastball quality and usage declined sharply. It wasn't until year two that all metrics normalized. This tells us that even when the ligament has been surgically repaired and is presumably healed from a structural standpoint, performance doesn't immediately follow. There's a lag between tissue integrity and functional output, which suggests that the relationship between structure and performance is more complex than just fixing what's broken. Another study examined return to performance in 129 MLB pitchers post-UCL surgery and found that while return-to-play rates were high, return-to-performance, especially full performance across key metrics, was far less common. Athletes were getting back on the mound, but many weren't getting back to the level they'd been at before surgery. If structure fully determined function, we'd expect better outcomes once the ligament was reconstructed, but that's not what the data shows.

Perhaps the most sobering evidence comes from research on revision UCL reconstruction. An analysis of 191 professional pitchers who underwent second UCL surgeries between 2010 and 2023 found that revision rates had increased 2.22 times compared to the previous 12-year average. While primary UCL reconstruction often restores careers, second-time surgery is far less forgiving. This escalation in revision surgeries raises questions about whether we're intervening on structural findings that didn't actually need surgical repair in the first place. If an athlete has a partial UCL tear visible on MRI but is asymptomatic, and we operate based on the imaging alone, we might be putting them through an unnecessary procedure that actually increases their long-term risk.

A prospective study of 128 high school baseball players provides additional insight into what actually predicts injury versus what just looks abnormal on imaging. The researchers followed athletes for six months, evaluating elbow structure via ultrasound, joint mobility, and wearable throwing data. Eighteen percent developed elbow pain lasting over a week despite being asymptomatic at baseline. The factors that predicted injury weren't the presence of structural abnormalities that might show up on an MRI, they were things like irregular medial epicondyles, which raised injury risk 5.4 times, and medial epicondyle hypertrophy, which raised risk 3.2 times. Nearly 70 percent of the athletes in this cohort had a prior elbow injury history, and that history, not their imaging findings or their throwing mechanics, was one of the strongest predictors of future breakdown. This reinforces the idea that clinical context, history, prior injury, symptoms, functional limitations, matters far more than what an MRI shows in isolation.

The challenge for clinicians is that there's no clear threshold that separates adaptive change from pathology. UCL thickening is common in asymptomatic throwers, but at what point does it become problematic? Osteophytes show up in healthy pitchers, but when do they transition from benign adaptation to a source of impingement or pain? Bone marrow edema can be present without symptoms, but it's also a sign of acute stress. The ability to make these distinctions isn't something you learn from a radiology textbook, it comes from seeing hundreds or thousands of MRIs in throwing athletes and understanding how the findings correlate, or don't correlate, with clinical outcomes. It requires pattern recognition that can only be developed through repeated exposure to this specific population.

Without that expertise, the default clinical response is often conservative in the worst way. An athlete with a thickened UCL or posteromedial changes gets pulled from throwing, even if they're asymptomatic, because the imaging suggests something is wrong. But shutting down a healthy athlete based on imaging alone creates its own set of problems. Deconditioning, loss of skill acquisition, psychological impact, and the financial and logistical burden of extended rest all have real consequences. And if the structural findings were adaptive rather than pathological, the rest period doesn't fix anything, it just delays the athlete's return to a sport they were handling just fine before someone decided to order an MRI.

How Can This Information Be Applied

If you're an athlete, parent, or coach dealing with MRI findings in a pitcher, the first and most important step is to work with a physician who has extensive experience evaluating throwing athletes. Not just orthopedists in general, not just sports medicine doctors in general, but clinicians who have spent significant time working with baseball pitchers and understand the unique demands of overhead throwing. This matters because the interpretation of imaging findings is not purely objective. Two radiologists looking at the same MRI can reach very different conclusions about what's clinically significant, and if one of them has spent their career seeing throwing elbows while the other hasn't, their assessments are going to diverge.

When you get an MRI report, read it carefully but don't let the language scare you. Words like "abnormal," "degenerative," "tear," and "pathology" carry a lot of weight, but in the context of an asymptomatic throwing athlete, they might not mean what you think they mean. A partial UCL tear in a 35-year-old office worker who hurt their elbow falling off a ladder is very different from a partial UCL tear in a 17-year-old pitcher who has no pain and has been throwing for years. The structural finding might look the same, but the clinical significance is completely different.

Symptoms matter more than imaging. If an athlete is pain-free, if they're not experiencing instability or mechanical symptoms like catching or locking, if their performance hasn't declined, and if their physical exam is unremarkable, then structural findings on MRI should be interpreted with extreme caution. The imaging might be revealing adaptation, not injury, and the appropriate response is often to continue monitoring rather than immediately intervening. This doesn't mean you ignore the findings, it means you put them in context and make decisions based on the whole clinical picture, not just what shows up on a scan.

Conversely, if an athlete has symptoms, pain, functional limitations, declining performance, then imaging can be useful to confirm what you already suspect based on the clinical presentation and to rule out other potential causes. But even in symptomatic athletes, the imaging findings need to be correlated with the symptoms. An athlete with medial elbow pain and a high-grade UCL tear on MRI probably has a UCL injury. An athlete with medial elbow pain and a normal-looking UCL but bone marrow edema in the sublime tubercle might have a bone stress issue rather than a ligament problem. The imaging helps narrow the differential and guide treatment, but it doesn't make the diagnosis on its own.

For young athletes especially, be extremely cautious about surgical intervention based primarily on imaging findings. The studies showing that 30 percent of asymptomatic players have high-grade UCL tears and 70 percent of pre-draft pitchers have structural abnormalities make it clear that surgery based on imaging alone, without corresponding symptoms and functional limitations, is likely overtreatment. UCL reconstruction is not a minor procedure. It requires 12 to 18 months of recovery, it fundamentally changes the mechanics of the elbow, and it carries risks of complications and incomplete return to performance. The decision to operate should be made when conservative management has failed and when the athlete's symptoms and functional deficits clearly warrant surgical intervention, not because an MRI shows a tear in someone who's otherwise doing fine.

Understand that imaging is a snapshot in time. A thickened UCL or posteromedial osteophyte doesn't tell you whether that change happened last month or three years ago. It doesn't tell you whether it's progressing or stable. It doesn't tell you whether it's adaptive or maladaptive. Serial imaging over time can provide some of that context, but even then, changes in imaging findings don't always correlate with changes in symptoms or function. An athlete whose UCL looks slightly worse on a follow-up MRI might feel and perform exactly the same, while another athlete whose imaging looks unchanged might have developed new symptoms.

If an athlete is going to get imaging, make sure there's a clear clinical reason for it. Screening MRIs in asymptomatic athletes are generally not recommended for exactly the reasons this research highlights, you're likely to find things that look abnormal but are actually normal for that population, and those findings create anxiety and pressure to intervene when intervention isn't needed. Imaging should be used to answer specific clinical questions when an athlete has symptoms or functional concerns that need further evaluation, not as a routine part of pre-participation physicals or as a way to "check" on an athlete who seems fine.

For clinicians ordering and interpreting imaging, develop relationships with radiologists who specialize in musculoskeletal imaging and who have experience with overhead athletes. Make sure the MRI report includes not just a description of findings but also a comment on clinical significance in the context of a throwing athlete. A report that says "thickened UCL, consider tear" is less helpful than a report that says "thickened UCL consistent with adaptive changes in a throwing athlete, no discrete tear identified, correlate clinically." The added context helps guide decision-making and reduces the likelihood that adaptive findings get treated as pathology.

Finally, recognize that even with all the right expertise and all the right context, there will be cases where it's genuinely unclear whether a structural finding represents adaptation or early pathology. The elbow exists on a continuum, and there isn't always a bright line separating healthy adaptation from maladaptive change. In those ambiguous cases, the conservative approach is often watchful waiting, continue monitoring symptoms, track performance, reassess periodically, and only escalate intervention if the clinical picture changes. This requires patience and tolerance for uncertainty, both of which can be difficult when you're dealing with a young athlete's career and when everyone involved just wants a clear answer. But rushing to intervene on imaging findings that might be normal carries its own risks, and those risks need to be weighed carefully.

Conclusion

The finding that nearly 70 percent of uninjured high school pitchers show structural abnormalities on MRI fundamentally challenges how we think about imaging in throwing athletes. These aren't rare anomalies, they're common adaptive responses to the repetitive high-magnitude loading that defines pitching. UCL thickening, posteromedial sclerosis, osteophytes, and even cartilage changes appear frequently in athletes who have no pain, no functional limitations, and no history of injury. The same patterns show up in professional pitchers, in elite prospects, and across different populations of throwers. What this tells us is that "abnormal" imaging findings are often the norm for this population, and interpreting them requires clinical expertise that goes far beyond basic radiology training.

The disconnect between structure and symptoms is clear in the research. Asymptomatic athletes frequently have high-grade UCL tears, symptomatic athletes sometimes have normal-looking ligaments, and the imaging findings that we think should predict clinical outcomes often don't. Return to play after surgery doesn't guarantee return to performance, and revision surgery rates are climbing, suggesting that we may be operating on structural findings that didn't need surgical intervention in the first place. All of this points to the same conclusion, imaging is a tool, not a diagnosis, and it must be interpreted in the context of an athlete's symptoms, physical exam, performance history, and the unique demands of their sport.

For athletes, parents, and coaches, the takeaway is straightforward but critical. Work with clinicians who have extensive experience evaluating throwing athletes, don't panic when an MRI shows findings that sound scary, prioritize symptoms and function over imaging abnormalities, and be extremely cautious about intervening on asymptomatic structural changes. The human body adapts to the demands placed on it, and in pitchers, that adaptation often looks abnormal to someone who doesn't understand the context. Learning to distinguish between healthy adaptation and true pathology is not easy, but it's essential if we want to avoid overtreating athletes who are doing just fine and undertreating the ones who actually need help. You are not your MRI, and the sooner we internalize that principle, the better equipped we'll be to make smart decisions about pitcher health and performance.

References

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