Curated By Nelson Vergel | ExcelMale.com | Updated April 2026
Summary: TRT improves bone density on imaging scans, but landmark clinical data from the TRAVERSE trial reveal a paradox: men on testosterone experienced significantly more clinical fractures than men on placebo. Add emerging evidence linking TRT to Achilles, rotator cuff, and quadriceps tendon injuries, and the picture becomes clear - TRT is a powerful treatment for hypogonadism symptoms, but it is not an anti-fracture or anti-injury therapy. This article explains why, what you can do about it, and how to protect your skeletal health while on TRT.
Introduction: When Better Labs Don't Mean Fewer Breaks
If you've started TRT in the past few years, you've almost certainly heard the encouraging news: testosterone improves bone mineral density. Your doctor may have pointed to studies showing that men on TRT develop denser spines and stronger hips. So why are researchers - and the clinicians who read their work - now recommending that men at risk for fractures think carefully before starting testosterone therapy?
The short answer is that better scans don't always mean fewer breaks. A landmark substudy published in the New England Journal of Medicine in January 2024 - drawn from the largest clinical trial of TRT ever conducted - found that men randomized to testosterone experienced a 43% higher rate of clinical fractures than men on placebo. At the same time, several large database studies have identified a meaningful association between TRT and tendon injuries, from torn Achilles tendons to rotator cuff ruptures.
None of this means you should avoid TRT. What it does mean is that TRT is a treatment for the symptoms of hypogonadism - low libido, fatigue, mood changes, anemia - and not a bone-strengthening or injury-prevention drug. If you're on TRT, or thinking about starting it, understanding this distinction can help you make smarter decisions about your exercise progression, your bone health monitoring, and whether you need additional treatment to protect your skeleton.
What TRAVERSE Was and Why It Matters
TRAVERSE (Testosterone Replacement Therapy for Assessment of Long-term Vascular Events and Efficacy Response in Hypogonadal Men) was a phase 4 clinical trial enrolling 5,246 men between the ages of 45 and 80. All participants had confirmed hypogonadism - two fasting morning testosterone levels below 300 ng/dL - and either existing cardiovascular disease or high cardiovascular risk. The trial was primarily designed to settle the long-running debate about TRT and heart risk, which it largely did by showing no increase in major cardiac events. But several pre-specified substudies tracked other outcomes, and one of them changed how thoughtful clinicians view TRT and bones.
The Numbers That Surprised Everyone
Across a median follow-up of 3.19 years, 91 men in the testosterone group (3.50%) suffered a confirmed clinical fracture, compared to 64 men in the placebo group (2.46%). The hazard ratio was 1.43 - meaning men on testosterone were 43% more likely to fracture than men on placebo. The finding held up across all fracture subtypes the researchers examined.
What makes this data especially thought-provoking is where the fractures occurred. The most common sites were ribs, wrists, and ankles - over 80% of fractures in both groups occurred with trauma, most commonly from falls. These are not the classic fragility fractures that come from ordinary, everyday loads. They're injury fractures - the kind that happen when you fall off a ladder, take a hard landing on a bike, or push harder in the gym than your frame can handle.
Interestingly, the fracture curves between the two groups began diverging almost immediately after treatment started - far too soon for any change in bone structure to explain the difference. At year 3, cumulative fracture incidence was 3.8% in the testosterone group versus 2.8% in the placebo group. Experts analyzing the data have largely concluded that the increased fracture risk is behavioral and biomechanical, not a sign that testosterone weakens bones.
The Bone Density Paradox: Why Better Scans Don't Tell the Full Story
What TRT Does to Bone - The Good News
It's worth being clear about what the evidence actually shows, because it's not all alarming. Testosterone does improve bone density - this finding is consistent across dozens of studies. The Testosterone Trials (TTrials) Bone Study, which enrolled men 65 and older with low testosterone, found that 12 months of testosterone gel increased trabecular spine volumetric bone mineral density (vBMD) by 6.8% and estimated spine bone strength by 8.5% compared to placebo. Hip vBMD also improved. These are real, meaningful gains in the surrogate measures that doctors typically use to assess fracture risk.
Earlier studies in men with classic organic hypogonadism - conditions like Klinefelter syndrome or pituitary failure that cause severe, documented testosterone deficiency - show even larger skeletal benefits from testosterone replacement. For this population, TRT clearly supports bone health and likely reduces fracture risk over the long term.
Why Scans and Real-World Outcomes Can Diverge
The disconnect between imaging results and clinical outcomes has a term in medicine: it's the difference between surrogate endpoints and hard clinical outcomes. A surrogate endpoint is a lab value or imaging finding that researchers use as a proxy for what they actually care about. Bone mineral density is a surrogate endpoint. An actual broken bone is a hard clinical outcome.
As the TRAVERSE data demonstrates, a surrogate endpoint can move in a favorable direction while hard outcomes move in an unfavorable direction. This is not unique to TRT - it has happened repeatedly in cardiovascular medicine, oncology, and other fields. It's a reason why large, long-duration trials that track real patient outcomes remain the gold standard, even when they contradict earlier surrogate-based studies.
One Australian cohort study of men over age 70 even found a U-shaped relationship between testosterone levels and fracture risk - suggesting that both very low and relatively high testosterone levels could independently elevate fracture risk. The mechanisms aren't fully understood, but the finding reinforces that optimizing testosterone is not the same as minimizing fracture risk.
The Mismatch of Adaptation: When Your Muscles Outpace Your Frame
The most compelling explanation for TRAVERSE's fracture paradox is what researchers call the Mismatch of Adaptation. Understanding this concept matters not just as an academic curiosity - it has direct practical implications for how you train when you're on TRT.
How Testosterone Affects Different Tissues at Different Speeds
Testosterone acts on multiple tissues through the androgen receptor, but it doesn't affect them at the same rate:
• Skeletal muscle responds rapidly. Testosterone stimulates myoblast proliferation, activates the Wnt/beta-catenin pathway, and inhibits the enzymes that break down muscle protein (MuRF1 and Atrogin-1). Within weeks of starting TRT, men begin experiencing increased protein synthesis. Across multiple clinical trials, TRT consistently produces gains in lean body mass of 1.6 to 4.7 kg.
• Tendons and ligaments adapt slowly. These connective tissues remodel through collagen synthesis and cross-linking - a process that takes months to years. Testosterone modulates matrix metalloproteinases (MMPs) and their inhibitors (TIMPs), which govern collagen remodeling. This may actually increase tendon stiffness in ways that amplify injury risk when loads increase suddenly.
• Bone adapts at an intermediate pace. Bone mineral density improvements, while real, take 6-12 months to become detectable on imaging and years to meaningfully translate into structural protection.
The result is a biological timing gap: your muscle force production upgrades significantly faster than the connective tissue and bone structures designed to handle that force. Think of it as installing a more powerful engine in a car without upgrading the brakes, suspension, or chassis.
The Behavioral Layer
This biological mismatch gets compounded by something predictable and human: when men feel better on TRT, they do more. Energy returns, confidence rises, and many men return to physical activities they'd stepped back from - often at higher intensities than before. Heavier gym lifts, more aggressive sports, physical labor that had felt too taxing. All of this increases load on the musculoskeletal system precisely during the early hazard window when connective tissue hasn't caught up.
Bradly Anawalt, MD, a professor at the University of Washington who presented a detailed analysis of the TRAVERSE fracture data at the 2025 Androgen Society Annual Meeting, concluded that behavioral change likely explains why fracture curves diverged so early in TRAVERSE: "That can't be due to changes in bone density or bone quality. It has to be due to something else to have those curves separate so quickly."
Side by Side: TTrials vs. TRAVERSE
These two landmark trials tell different stories because they measured different things:
The Tendon Problem: When Confidence Outpaces Collagen
Fractures aren't the only musculoskeletal concern for men on TRT. A growing body of data from large insurance databases points to a consistent association between TRT and tendon injuries across several anatomical sites. These findings echo what was long known about supraphysiologic anabolic steroid use, but now the signal is appearing at therapeutic doses too.
What the PearlDiver Database Studies Found
The PearlDiver database - which contains insurance claims data on tens of millions of Americans - has been queried by several research groups specifically to examine TRT and tendon outcomes. Key findings include:
• Achilles tendon: A 2023 matched retrospective cohort study analyzed 423,278 patients who filled TRT prescriptions for at least three consecutive months. TRT was associated with a significantly increased odds of Achilles tendon injury (adjusted odds ratio 1.24; 95% CI, 1.15-1.33). Even more striking, those on TRT who did injure their Achilles were significantly more likely to need surgery (adjusted OR 1.54; 95% CI, 1.19-1.99).
• Rotator cuff: A separate PearlDiver analysis found TRT patients had 3.57 times greater odds of sustaining a rotator cuff tear than matched controls. Among those who required repair, TRT patients had a 26-fold greater risk of needing a subsequent (revision) repair within one year.
• Quadriceps tendon: Another study in the same database found increased odds of quadriceps muscle and tendon injury in men prescribed testosterone, with a higher rate of surgical repair as well.
Important caveats apply to all database studies. Men on TRT are more health-aware on average, more likely to seek care for musculoskeletal symptoms, and more active than average - which could inflate injury rates through detection bias. Still, the surgical repair numbers are harder to explain by detection bias alone: you generally only get surgery when there's a real structural problem.
Why Tendons Are Especially Vulnerable
Tendons are mostly made of type I collagen - dense, inelastic connective tissue that provides the mechanical link between muscle and bone. Testosterone modulates the balance between the enzymes that build collagen (including TIMPs) and the enzymes that break it down (MMPs). In animal studies, anabolic steroids have been shown to reduce collagen synthesis and create tendons that are paradoxically stiffer but more prone to rupture.
The mechanism is thought to be this: rapidly increasing muscle mass generates greater force on tendons. If tendon tissue hasn't had time to adapt - through progressive loading and collagen remodeling - the suddenly more powerful muscle can literally tear the tendon off the bone. This is most likely to happen when a man transitions quickly from relative inactivity to high-load exercise, which is exactly what many men do when their energy and confidence return on TRT.
Who Is Most at Risk? Identifying Your Vulnerability Window
The First Year Is Critical
Clinical data consistently identifies the first 12 months of TRT as the highest-risk period for both tendon injuries and traumatic fractures. The muscle-tendon mismatch is widest during this window, and the behavioral surge in activity levels tends to be greatest early in treatment when the novelty of improved energy is most pronounced.
Men who are starting from a lower baseline of physical activity face the steepest risk because they experience the most dramatic change in both capacity and motivation. Someone who goes from sedentary to hitting the gym five days a week after starting TRT creates exactly the kind of abrupt load increase that the connective tissue biology can't handle.
Risk Factors That Compound the Problem
• Age 60 and above: Reduced regenerative capacity in tendons and ligaments, lower baseline connective tissue quality, and slower bone remodeling all amplify the mismatch.
• Prior tendon injury or tendinopathy: Pre-existing structural weakness is a significant vulnerability. If you've had shoulder, Achilles, or knee tendon problems before TRT, those areas are at higher risk after.
• High-impact or overhead sports: Activities like recreational basketball, racquet sports, heavy barbell lifting, and CrossFit-style training place particularly high loads on the tendons most commonly injured in TRT users.
• Injection formulations with high peak-to-trough variability: Short-acting injections (such as weekly testosterone cypionate or enanthate) create peaks of hormone exposure that may amplify the biological mismatch compared to stable transdermal preparations.
• Concurrent use of fluoroquinolone antibiotics: This drug class independently increases tendon rupture risk - the combination with TRT has not been formally studied but warrants caution.
When Should You Get a DXA Scan?
If you're over 50, have had low testosterone for a prolonged period, or have any risk factors for osteoporosis (smoking history, alcohol use, low body weight, corticosteroid use, family history of hip fracture), a baseline DXA scan is worth discussing with your doctor. The purpose isn't to decide whether to start TRT - it's to establish a baseline and identify whether you need bone-protective therapy alongside or instead of TRT.
If your DXA shows osteopenia or osteoporosis, TRT is not a substitute for guideline-based anti-osteoporotic medications such as bisphosphonates or denosumab. Steven Nissen, MD, the TRAVERSE trial chair at Cleveland Clinic, stated it plainly: "If men have a history of osteoporosis, they probably shouldn't be taking testosterone, and they certainly shouldn't take testosterone to reduce their risk of fracture because it appears to actually increase that risk."
Practical Protocol: How to Protect Your Skeleton on TRT
1. Adjust Your Exercise Progression - Deliberately
The single most actionable thing you can do to reduce your musculoskeletal risk on TRT is to resist the urge to ramp up exercise intensity rapidly when you start feeling better. A structured, graded progression gives your tendons and bones time to adapt to new loading demands.
• Increase weights or intensity no more than 5-10% per week rather than jumping to previous personal bests.
• Prioritize eccentric loading in your tendon-specific exercises - slow negatives in the gym are particularly effective at promoting tendon collagen remodeling.
• Add balance and proprioception training: balance-board exercises, single-leg work, and agility drills directly reduce fall-related fracture risk without requiring high tendon loads.
• Give yourself at least 6-12 months of consistent, progressive training before pushing to maximum intensity levels in high-risk activities.
2. Have an Honest Conversation About Osteoporosis Risk
Ask your prescribing physician whether a DXA scan makes sense for you. If you already have documented bone loss, ask specifically whether you need bone-protective therapy alongside TRT, not just in addition to it as an afterthought. Remember: TRT does not replace bisphosphonates or other anti-osteoporotic therapies in high-risk men. It is a separate intervention with different mechanisms and different effects.
3. Consider Formulation Pharmacokinetics
Transdermal testosterone gel or patch - which provides a stable, consistent hormone level throughout the day - may create a smaller mismatch between perceived energy and actual physical capacity compared to weekly injections that produce sharp peaks followed by troughs. This doesn't mean injections are contraindicated, but if you're in a high-risk category for musculoskeletal injury, the smoother pharmacokinetic profile of transdermal therapy is worth discussing with your prescriber.
4. Monitor the Right Labs - Including the Ones for Bone
Standard TRT monitoring includes testosterone levels, hematocrit, PSA, and blood pressure. For men with bone concerns, consider asking about:
• 25-hydroxyvitamin D: Many hypogonadal men are vitamin D deficient, and vitamin D is critical for calcium absorption and bone remodeling. Target a level above 40 ng/mL.
• Serum calcium: A simple screening test for metabolic bone issues.
• FRAX score: A WHO-developed fracture risk assessment tool that estimates your 10-year risk of hip fracture and major osteoporotic fracture. Your doctor can calculate this using your BMD results and clinical risk factors.
• Bone turnover markers such as osteocalcin and CTX-1 are used in research settings but can sometimes add clinical insight about the direction of bone remodeling.
5. Don't Neglect Nutrition for Connective Tissue Health
While testosterone creates an anabolic environment, it can't build bone or tendon from nothing. Adequate calcium (1,000-1,200 mg/day from food and supplements combined), vitamin D (1,500-2,000 IU/day for most men with deficiency), and dietary protein (at least 1.2 g/kg body weight per day) all support the musculoskeletal adaptations you want. Collagen peptide supplementation (10-15g/day) taken around training has some emerging evidence for supporting tendon collagen synthesis, though the data is preliminary.
The Regulatory Picture: What the FDA and EMA Are Saying
The post-TRAVERSE regulatory landscape has reinforced the message that TRT is a treatment for symptomatic hypogonadism - not a general health optimization or anti-aging intervention. Some key regulatory updates relevant to musculoskeletal health and safety:
• The FDA has issued updated labeling for testosterone products requiring warnings about blood pressure elevation. This matters for skeletal health indirectly: uncontrolled hypertension increases cardiovascular risk, which affects overall physical activity safety and recovery.
• The European Medicines Agency (EMA) has emphasized heightened vigilance for erythrocytosis (high red blood cell count) with TRT. Men taking SGLT2 inhibitors for diabetes or heart failure face additive erythrocytosis risk - hematocrit must be monitored carefully in this combination, as high hematocrit affects blood viscosity and overall cardiovascular risk.
• For oil-based long-acting injectables (testosterone undecanoate), regulators have reinforced warnings about Pulmonary Oil Microembolism (POME) risk. While rare, correct injection technique and post-injection observation time remain important.
• Both the FDA and major endocrinology societies continue to emphasize that TRT indications require two confirmed low morning testosterone measurements and documented symptoms. Using TRT for general "age-related decline" without clinical hypogonadism falls outside evidence-based practice - and the TRAVERSE data suggests it doesn't carry the skeletal benefits one might hope for.
Who Does Benefit Skeletally? Classical vs. Functional Hypogonadism
Not everyone is at the same risk profile from TRAVERSE's findings. The trial enrolled men with moderate, largely functional hypogonadism - many of whom had low testosterone driven by obesity, metabolic syndrome, and cardiovascular disease rather than true primary or secondary hypothalamic-pituitary-testicular failure.
Men with classical organic hypogonadism - caused by conditions like Klinefelter syndrome, pituitary tumors, testicular failure, or radiation damage - appear to derive genuine long-term skeletal benefit from testosterone replacement. In this population, the hypogonadism is severe, persistent, and driven by genuine anatomical or structural pathology. Studies in Klinefelter syndrome, for example, show bone fragility that worsens without treatment and improves substantially with TRT.
Men with functional (late-onset) hypogonadism - where low testosterone is largely driven by obesity, insulin resistance, sleep apnea, or chronic illness - occupy a different risk-benefit position. In this group, lifestyle modifications that address the root cause (weight loss, sleep apnea treatment, improved metabolic health) can sometimes restore testosterone without the need for replacement therapy, and the skeletal benefits of exogenous testosterone may be less certain.
If you're unsure which category applies to you, this is exactly the type of nuanced conversation the ExcelMale community has been having for years - and a qualified hormone specialist can help you understand your specific situation.
Related ExcelMale Forum Discussions
Explore these community discussions for additional insights and real-world experiences from men navigating TRT and musculoskeletal health:
- Patients Taking Hormones Seem to Be at a Higher Risk of Tendon Injury - Comprehensive review of the orthopedic surgery literature on TRT, AAS, and musculotendinous injury risk, with forum member discussion.
- Nandrolone Plus TRT Protocols for Joint Support and Bone Health - Discusses nandrolone's collagen-enhancing properties and its potential role in mitigating TRT-related connective tissue vulnerability.
- Exercise for Muscle, Bone, and Longevity on TRT - Community perspectives on structuring training to maximize TRT benefits while protecting joints and bones.
- Hematocrit Management on TRT: When to Donate and When to Lower Your Dose - Thorough discussion of erythrocytosis, its cardiovascular and vascular implications, and management strategies.
- Estradiol's Role in Men on TRT: The Bone Connection and Why You Should Not Crash It - Explains why maintaining adequate estradiol levels on TRT is critical for bone health - aromatization to E2 is a key mediator of testosterone's skeletal effects.
- DXA Scans and Bone Health Monitoring for Men on Long-Term TRT - Community discussion of when to get bone density scans, how to interpret results, and when to ask about bisphosphonates.
- Vitamin D and Testosterone: The Underrated Connection - Discussion of vitamin D deficiency in hypogonadal men, its role in bone remodeling, and optimal supplementation strategies.
- Managing Achilles and Rotator Cuff Pain While on TRT - Practical member experiences dealing with tendinopathy on TRT, including eccentric loading protocols and when to modify training.
- Testosterone Injection Frequency and Its Effect on How You Feel - Examines how injection frequency affects hormone peaks and troughs, which has implications for the muscle-tendon mismatch discussed in this article.
Key References
1. Snyder PJ, Bauer DC, Ellenberg SS, et al. Testosterone Treatment and Fractures in Men with Hypogonadism. N Engl J Med. 2024;390:203-211. https://doi.org/10.1056/NEJMoa2308836
2. Snyder PJ, Kopperdahl DL, Stephens-Shields AJ, et al. Effect of Testosterone Treatment on Volumetric Bone Density and Strength in Older Men With Low Testosterone. JAMA Intern Med. 2017;177:471-479. https://doi.org/10.1001/jamainternmed.2016.9539
3. Lincoff AM, Bhasin S, Flevaris P, et al. Cardiovascular Safety of Testosterone-Replacement Therapy. N Engl J Med. 2023;389:107-117. https://doi.org/10.1056/NEJMoa2212321
4. Albright J, Lou M, Rebello E, et al. Testosterone Replacement Therapy Is Associated With Increased Odds of Achilles Tendon Injury and Subsequent Surgery. J Foot Ankle Res. 2023;16:78. https://doi.org/10.1186/s13047-023-00678-0
5. Testa EJ, Albright JA, Hartnett D, et al. The Relationship Between Testosterone Therapy and Rotator Cuff Tears, Repairs, and Revision Repairs. J Am Acad Orthop Surg. 2023;31(11):581-588. https://pubmed.ncbi.nlm.nih.gov/36898059/
6. Gould HP, Hawken JB, Duvall GT, Hammond JW. Testosterone Therapy Is Associated With Increased Odds of Quadriceps Tendon Injury. Clin Orthop Relat Res. 2024;482:179-190. https://doi.org/10.1097/CORR.0000000000002778
7. Grossmann M, Anawalt BD. Breaking News - Testosterone Treatment and Fractures in Older Men. N Engl J Med. 2024;390:267-268. https://doi.org/10.1056/NEJMe2313787
8. Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103:1715-1744. https://doi.org/10.1210/jc.2018-00229
9. Goto NA, Weststrate ACG, Verhaar MC, et al. Testosterone Replacement Therapy in Older Men: Skeletal Outcomes and Fracture Risk. Aging Male. 2026. https://doi.org/10.1080/13685538.2026.2655544
10. Morales A, Lunenfeld B. Investigation, Treatment and Monitoring of Late-Onset Hypogonadism in Males. Aging Male. 2002;5:74-86. https://doi.org/10.1080/tam.5.2.74.86
Medical Disclaimer
The information presented in this article is for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual circumstances vary significantly, and men considering or currently using testosterone replacement therapy should consult with a qualified healthcare provider familiar with their complete medical history. Do not start, stop, or modify any medical therapy based solely on information contained herein.
About ExcelMale.com
ExcelMale.com is the internet's most trusted, expert-moderated men's health community, with over 24,000 members and more than 20 years of archived discussions on testosterone replacement therapy, hormone optimization, sexual health, and men's wellness. Founded by Nelson Vergel, a chemical engineer turned patient advocate who has been on TRT for over 30 years, ExcelMale provides a rigorously evidence-based space where men can access real clinical information and connect with others navigating similar health journeys.
Nelson Vergel is the author of Testosterone: A Man's Guide and Beyond Testosterone. Visit www.ExcelMale.com to join the community and access the full archive of evidence-based men's health content.
Summary: TRT improves bone density on imaging scans, but landmark clinical data from the TRAVERSE trial reveal a paradox: men on testosterone experienced significantly more clinical fractures than men on placebo. Add emerging evidence linking TRT to Achilles, rotator cuff, and quadriceps tendon injuries, and the picture becomes clear - TRT is a powerful treatment for hypogonadism symptoms, but it is not an anti-fracture or anti-injury therapy. This article explains why, what you can do about it, and how to protect your skeletal health while on TRT.
Introduction: When Better Labs Don't Mean Fewer Breaks
If you've started TRT in the past few years, you've almost certainly heard the encouraging news: testosterone improves bone mineral density. Your doctor may have pointed to studies showing that men on TRT develop denser spines and stronger hips. So why are researchers - and the clinicians who read their work - now recommending that men at risk for fractures think carefully before starting testosterone therapy?
The short answer is that better scans don't always mean fewer breaks. A landmark substudy published in the New England Journal of Medicine in January 2024 - drawn from the largest clinical trial of TRT ever conducted - found that men randomized to testosterone experienced a 43% higher rate of clinical fractures than men on placebo. At the same time, several large database studies have identified a meaningful association between TRT and tendon injuries, from torn Achilles tendons to rotator cuff ruptures.
None of this means you should avoid TRT. What it does mean is that TRT is a treatment for the symptoms of hypogonadism - low libido, fatigue, mood changes, anemia - and not a bone-strengthening or injury-prevention drug. If you're on TRT, or thinking about starting it, understanding this distinction can help you make smarter decisions about your exercise progression, your bone health monitoring, and whether you need additional treatment to protect your skeleton.
What TRAVERSE Was and Why It Matters
TRAVERSE (Testosterone Replacement Therapy for Assessment of Long-term Vascular Events and Efficacy Response in Hypogonadal Men) was a phase 4 clinical trial enrolling 5,246 men between the ages of 45 and 80. All participants had confirmed hypogonadism - two fasting morning testosterone levels below 300 ng/dL - and either existing cardiovascular disease or high cardiovascular risk. The trial was primarily designed to settle the long-running debate about TRT and heart risk, which it largely did by showing no increase in major cardiac events. But several pre-specified substudies tracked other outcomes, and one of them changed how thoughtful clinicians view TRT and bones.
The Numbers That Surprised Everyone
Across a median follow-up of 3.19 years, 91 men in the testosterone group (3.50%) suffered a confirmed clinical fracture, compared to 64 men in the placebo group (2.46%). The hazard ratio was 1.43 - meaning men on testosterone were 43% more likely to fracture than men on placebo. The finding held up across all fracture subtypes the researchers examined.
What makes this data especially thought-provoking is where the fractures occurred. The most common sites were ribs, wrists, and ankles - over 80% of fractures in both groups occurred with trauma, most commonly from falls. These are not the classic fragility fractures that come from ordinary, everyday loads. They're injury fractures - the kind that happen when you fall off a ladder, take a hard landing on a bike, or push harder in the gym than your frame can handle.
Interestingly, the fracture curves between the two groups began diverging almost immediately after treatment started - far too soon for any change in bone structure to explain the difference. At year 3, cumulative fracture incidence was 3.8% in the testosterone group versus 2.8% in the placebo group. Experts analyzing the data have largely concluded that the increased fracture risk is behavioral and biomechanical, not a sign that testosterone weakens bones.
| Key Takeaways From the TRAVERSE Fracture Data • Men on testosterone had a 43% higher clinical fracture rate than men on placebo (HR = 1.43; 95% CI, 1.04-1.97; p = 0.03) • Most fractures were traumatic (falls, impacts) - not fragility fractures from low bone quality • Fractures began appearing more frequently almost immediately, before TRT could meaningfully change bone density • TRT is not an anti-fracture therapy and should never replace bone-protective medications in men at high risk • TRAVERSE researchers did not design the trial to identify the mechanism - more research is underway |
The Bone Density Paradox: Why Better Scans Don't Tell the Full Story
What TRT Does to Bone - The Good News
It's worth being clear about what the evidence actually shows, because it's not all alarming. Testosterone does improve bone density - this finding is consistent across dozens of studies. The Testosterone Trials (TTrials) Bone Study, which enrolled men 65 and older with low testosterone, found that 12 months of testosterone gel increased trabecular spine volumetric bone mineral density (vBMD) by 6.8% and estimated spine bone strength by 8.5% compared to placebo. Hip vBMD also improved. These are real, meaningful gains in the surrogate measures that doctors typically use to assess fracture risk.
Earlier studies in men with classic organic hypogonadism - conditions like Klinefelter syndrome or pituitary failure that cause severe, documented testosterone deficiency - show even larger skeletal benefits from testosterone replacement. For this population, TRT clearly supports bone health and likely reduces fracture risk over the long term.
Why Scans and Real-World Outcomes Can Diverge
The disconnect between imaging results and clinical outcomes has a term in medicine: it's the difference between surrogate endpoints and hard clinical outcomes. A surrogate endpoint is a lab value or imaging finding that researchers use as a proxy for what they actually care about. Bone mineral density is a surrogate endpoint. An actual broken bone is a hard clinical outcome.
As the TRAVERSE data demonstrates, a surrogate endpoint can move in a favorable direction while hard outcomes move in an unfavorable direction. This is not unique to TRT - it has happened repeatedly in cardiovascular medicine, oncology, and other fields. It's a reason why large, long-duration trials that track real patient outcomes remain the gold standard, even when they contradict earlier surrogate-based studies.
One Australian cohort study of men over age 70 even found a U-shaped relationship between testosterone levels and fracture risk - suggesting that both very low and relatively high testosterone levels could independently elevate fracture risk. The mechanisms aren't fully understood, but the finding reinforces that optimizing testosterone is not the same as minimizing fracture risk.
The Mismatch of Adaptation: When Your Muscles Outpace Your Frame
The most compelling explanation for TRAVERSE's fracture paradox is what researchers call the Mismatch of Adaptation. Understanding this concept matters not just as an academic curiosity - it has direct practical implications for how you train when you're on TRT.
How Testosterone Affects Different Tissues at Different Speeds
Testosterone acts on multiple tissues through the androgen receptor, but it doesn't affect them at the same rate:
• Skeletal muscle responds rapidly. Testosterone stimulates myoblast proliferation, activates the Wnt/beta-catenin pathway, and inhibits the enzymes that break down muscle protein (MuRF1 and Atrogin-1). Within weeks of starting TRT, men begin experiencing increased protein synthesis. Across multiple clinical trials, TRT consistently produces gains in lean body mass of 1.6 to 4.7 kg.
• Tendons and ligaments adapt slowly. These connective tissues remodel through collagen synthesis and cross-linking - a process that takes months to years. Testosterone modulates matrix metalloproteinases (MMPs) and their inhibitors (TIMPs), which govern collagen remodeling. This may actually increase tendon stiffness in ways that amplify injury risk when loads increase suddenly.
• Bone adapts at an intermediate pace. Bone mineral density improvements, while real, take 6-12 months to become detectable on imaging and years to meaningfully translate into structural protection.
The result is a biological timing gap: your muscle force production upgrades significantly faster than the connective tissue and bone structures designed to handle that force. Think of it as installing a more powerful engine in a car without upgrading the brakes, suspension, or chassis.
The Behavioral Layer
This biological mismatch gets compounded by something predictable and human: when men feel better on TRT, they do more. Energy returns, confidence rises, and many men return to physical activities they'd stepped back from - often at higher intensities than before. Heavier gym lifts, more aggressive sports, physical labor that had felt too taxing. All of this increases load on the musculoskeletal system precisely during the early hazard window when connective tissue hasn't caught up.
Bradly Anawalt, MD, a professor at the University of Washington who presented a detailed analysis of the TRAVERSE fracture data at the 2025 Androgen Society Annual Meeting, concluded that behavioral change likely explains why fracture curves diverged so early in TRAVERSE: "That can't be due to changes in bone density or bone quality. It has to be due to something else to have those curves separate so quickly."
Side by Side: TTrials vs. TRAVERSE
These two landmark trials tell different stories because they measured different things:
| Feature | Testosterone Trials (TTrials) | TRAVERSE Fracture Substudy |
| Population | Men ≥65; average T <275 ng/dL; symptomatic | Men 45-80; T <300 ng/dL; high CV risk |
| Follow-Up | 12 months | Median 3.19 years |
| Primary Bone Endpoint | Volumetric BMD and estimated bone strength (imaging surrogates) | Actual clinical fractures (hard clinical outcome) |
| Key Finding | 6.8% increase in spine vBMD; falls unchanged (~27% in both groups) | HR 1.43 - 43% more clinical fractures in TRT group |
| Bottom Line | TRT improves bone surrogates but does not reduce falls | TRT does not lower fracture risk and may increase it - likely behavioral |
The Tendon Problem: When Confidence Outpaces Collagen
Fractures aren't the only musculoskeletal concern for men on TRT. A growing body of data from large insurance databases points to a consistent association between TRT and tendon injuries across several anatomical sites. These findings echo what was long known about supraphysiologic anabolic steroid use, but now the signal is appearing at therapeutic doses too.
What the PearlDiver Database Studies Found
The PearlDiver database - which contains insurance claims data on tens of millions of Americans - has been queried by several research groups specifically to examine TRT and tendon outcomes. Key findings include:
• Achilles tendon: A 2023 matched retrospective cohort study analyzed 423,278 patients who filled TRT prescriptions for at least three consecutive months. TRT was associated with a significantly increased odds of Achilles tendon injury (adjusted odds ratio 1.24; 95% CI, 1.15-1.33). Even more striking, those on TRT who did injure their Achilles were significantly more likely to need surgery (adjusted OR 1.54; 95% CI, 1.19-1.99).
• Rotator cuff: A separate PearlDiver analysis found TRT patients had 3.57 times greater odds of sustaining a rotator cuff tear than matched controls. Among those who required repair, TRT patients had a 26-fold greater risk of needing a subsequent (revision) repair within one year.
• Quadriceps tendon: Another study in the same database found increased odds of quadriceps muscle and tendon injury in men prescribed testosterone, with a higher rate of surgical repair as well.
Important caveats apply to all database studies. Men on TRT are more health-aware on average, more likely to seek care for musculoskeletal symptoms, and more active than average - which could inflate injury rates through detection bias. Still, the surgical repair numbers are harder to explain by detection bias alone: you generally only get surgery when there's a real structural problem.
Why Tendons Are Especially Vulnerable
Tendons are mostly made of type I collagen - dense, inelastic connective tissue that provides the mechanical link between muscle and bone. Testosterone modulates the balance between the enzymes that build collagen (including TIMPs) and the enzymes that break it down (MMPs). In animal studies, anabolic steroids have been shown to reduce collagen synthesis and create tendons that are paradoxically stiffer but more prone to rupture.
The mechanism is thought to be this: rapidly increasing muscle mass generates greater force on tendons. If tendon tissue hasn't had time to adapt - through progressive loading and collagen remodeling - the suddenly more powerful muscle can literally tear the tendon off the bone. This is most likely to happen when a man transitions quickly from relative inactivity to high-load exercise, which is exactly what many men do when their energy and confidence return on TRT.
Who Is Most at Risk? Identifying Your Vulnerability Window
The First Year Is Critical
Clinical data consistently identifies the first 12 months of TRT as the highest-risk period for both tendon injuries and traumatic fractures. The muscle-tendon mismatch is widest during this window, and the behavioral surge in activity levels tends to be greatest early in treatment when the novelty of improved energy is most pronounced.
Men who are starting from a lower baseline of physical activity face the steepest risk because they experience the most dramatic change in both capacity and motivation. Someone who goes from sedentary to hitting the gym five days a week after starting TRT creates exactly the kind of abrupt load increase that the connective tissue biology can't handle.
Risk Factors That Compound the Problem
• Age 60 and above: Reduced regenerative capacity in tendons and ligaments, lower baseline connective tissue quality, and slower bone remodeling all amplify the mismatch.
• Prior tendon injury or tendinopathy: Pre-existing structural weakness is a significant vulnerability. If you've had shoulder, Achilles, or knee tendon problems before TRT, those areas are at higher risk after.
• High-impact or overhead sports: Activities like recreational basketball, racquet sports, heavy barbell lifting, and CrossFit-style training place particularly high loads on the tendons most commonly injured in TRT users.
• Injection formulations with high peak-to-trough variability: Short-acting injections (such as weekly testosterone cypionate or enanthate) create peaks of hormone exposure that may amplify the biological mismatch compared to stable transdermal preparations.
• Concurrent use of fluoroquinolone antibiotics: This drug class independently increases tendon rupture risk - the combination with TRT has not been formally studied but warrants caution.
When Should You Get a DXA Scan?
If you're over 50, have had low testosterone for a prolonged period, or have any risk factors for osteoporosis (smoking history, alcohol use, low body weight, corticosteroid use, family history of hip fracture), a baseline DXA scan is worth discussing with your doctor. The purpose isn't to decide whether to start TRT - it's to establish a baseline and identify whether you need bone-protective therapy alongside or instead of TRT.
If your DXA shows osteopenia or osteoporosis, TRT is not a substitute for guideline-based anti-osteoporotic medications such as bisphosphonates or denosumab. Steven Nissen, MD, the TRAVERSE trial chair at Cleveland Clinic, stated it plainly: "If men have a history of osteoporosis, they probably shouldn't be taking testosterone, and they certainly shouldn't take testosterone to reduce their risk of fracture because it appears to actually increase that risk."
Practical Protocol: How to Protect Your Skeleton on TRT
1. Adjust Your Exercise Progression - Deliberately
The single most actionable thing you can do to reduce your musculoskeletal risk on TRT is to resist the urge to ramp up exercise intensity rapidly when you start feeling better. A structured, graded progression gives your tendons and bones time to adapt to new loading demands.
• Increase weights or intensity no more than 5-10% per week rather than jumping to previous personal bests.
• Prioritize eccentric loading in your tendon-specific exercises - slow negatives in the gym are particularly effective at promoting tendon collagen remodeling.
• Add balance and proprioception training: balance-board exercises, single-leg work, and agility drills directly reduce fall-related fracture risk without requiring high tendon loads.
• Give yourself at least 6-12 months of consistent, progressive training before pushing to maximum intensity levels in high-risk activities.
2. Have an Honest Conversation About Osteoporosis Risk
Ask your prescribing physician whether a DXA scan makes sense for you. If you already have documented bone loss, ask specifically whether you need bone-protective therapy alongside TRT, not just in addition to it as an afterthought. Remember: TRT does not replace bisphosphonates or other anti-osteoporotic therapies in high-risk men. It is a separate intervention with different mechanisms and different effects.
3. Consider Formulation Pharmacokinetics
Transdermal testosterone gel or patch - which provides a stable, consistent hormone level throughout the day - may create a smaller mismatch between perceived energy and actual physical capacity compared to weekly injections that produce sharp peaks followed by troughs. This doesn't mean injections are contraindicated, but if you're in a high-risk category for musculoskeletal injury, the smoother pharmacokinetic profile of transdermal therapy is worth discussing with your prescriber.
4. Monitor the Right Labs - Including the Ones for Bone
Standard TRT monitoring includes testosterone levels, hematocrit, PSA, and blood pressure. For men with bone concerns, consider asking about:
• 25-hydroxyvitamin D: Many hypogonadal men are vitamin D deficient, and vitamin D is critical for calcium absorption and bone remodeling. Target a level above 40 ng/mL.
• Serum calcium: A simple screening test for metabolic bone issues.
• FRAX score: A WHO-developed fracture risk assessment tool that estimates your 10-year risk of hip fracture and major osteoporotic fracture. Your doctor can calculate this using your BMD results and clinical risk factors.
• Bone turnover markers such as osteocalcin and CTX-1 are used in research settings but can sometimes add clinical insight about the direction of bone remodeling.
5. Don't Neglect Nutrition for Connective Tissue Health
While testosterone creates an anabolic environment, it can't build bone or tendon from nothing. Adequate calcium (1,000-1,200 mg/day from food and supplements combined), vitamin D (1,500-2,000 IU/day for most men with deficiency), and dietary protein (at least 1.2 g/kg body weight per day) all support the musculoskeletal adaptations you want. Collagen peptide supplementation (10-15g/day) taken around training has some emerging evidence for supporting tendon collagen synthesis, though the data is preliminary.
The Regulatory Picture: What the FDA and EMA Are Saying
The post-TRAVERSE regulatory landscape has reinforced the message that TRT is a treatment for symptomatic hypogonadism - not a general health optimization or anti-aging intervention. Some key regulatory updates relevant to musculoskeletal health and safety:
• The FDA has issued updated labeling for testosterone products requiring warnings about blood pressure elevation. This matters for skeletal health indirectly: uncontrolled hypertension increases cardiovascular risk, which affects overall physical activity safety and recovery.
• The European Medicines Agency (EMA) has emphasized heightened vigilance for erythrocytosis (high red blood cell count) with TRT. Men taking SGLT2 inhibitors for diabetes or heart failure face additive erythrocytosis risk - hematocrit must be monitored carefully in this combination, as high hematocrit affects blood viscosity and overall cardiovascular risk.
• For oil-based long-acting injectables (testosterone undecanoate), regulators have reinforced warnings about Pulmonary Oil Microembolism (POME) risk. While rare, correct injection technique and post-injection observation time remain important.
• Both the FDA and major endocrinology societies continue to emphasize that TRT indications require two confirmed low morning testosterone measurements and documented symptoms. Using TRT for general "age-related decline" without clinical hypogonadism falls outside evidence-based practice - and the TRAVERSE data suggests it doesn't carry the skeletal benefits one might hope for.
Who Does Benefit Skeletally? Classical vs. Functional Hypogonadism
Not everyone is at the same risk profile from TRAVERSE's findings. The trial enrolled men with moderate, largely functional hypogonadism - many of whom had low testosterone driven by obesity, metabolic syndrome, and cardiovascular disease rather than true primary or secondary hypothalamic-pituitary-testicular failure.
Men with classical organic hypogonadism - caused by conditions like Klinefelter syndrome, pituitary tumors, testicular failure, or radiation damage - appear to derive genuine long-term skeletal benefit from testosterone replacement. In this population, the hypogonadism is severe, persistent, and driven by genuine anatomical or structural pathology. Studies in Klinefelter syndrome, for example, show bone fragility that worsens without treatment and improves substantially with TRT.
Men with functional (late-onset) hypogonadism - where low testosterone is largely driven by obesity, insulin resistance, sleep apnea, or chronic illness - occupy a different risk-benefit position. In this group, lifestyle modifications that address the root cause (weight loss, sleep apnea treatment, improved metabolic health) can sometimes restore testosterone without the need for replacement therapy, and the skeletal benefits of exogenous testosterone may be less certain.
If you're unsure which category applies to you, this is exactly the type of nuanced conversation the ExcelMale community has been having for years - and a qualified hormone specialist can help you understand your specific situation.
Related ExcelMale Forum Discussions
Explore these community discussions for additional insights and real-world experiences from men navigating TRT and musculoskeletal health:
- Patients Taking Hormones Seem to Be at a Higher Risk of Tendon Injury - Comprehensive review of the orthopedic surgery literature on TRT, AAS, and musculotendinous injury risk, with forum member discussion.
- Nandrolone Plus TRT Protocols for Joint Support and Bone Health - Discusses nandrolone's collagen-enhancing properties and its potential role in mitigating TRT-related connective tissue vulnerability.
- Exercise for Muscle, Bone, and Longevity on TRT - Community perspectives on structuring training to maximize TRT benefits while protecting joints and bones.
- Hematocrit Management on TRT: When to Donate and When to Lower Your Dose - Thorough discussion of erythrocytosis, its cardiovascular and vascular implications, and management strategies.
- Estradiol's Role in Men on TRT: The Bone Connection and Why You Should Not Crash It - Explains why maintaining adequate estradiol levels on TRT is critical for bone health - aromatization to E2 is a key mediator of testosterone's skeletal effects.
- DXA Scans and Bone Health Monitoring for Men on Long-Term TRT - Community discussion of when to get bone density scans, how to interpret results, and when to ask about bisphosphonates.
- Vitamin D and Testosterone: The Underrated Connection - Discussion of vitamin D deficiency in hypogonadal men, its role in bone remodeling, and optimal supplementation strategies.
- Managing Achilles and Rotator Cuff Pain While on TRT - Practical member experiences dealing with tendinopathy on TRT, including eccentric loading protocols and when to modify training.
- Testosterone Injection Frequency and Its Effect on How You Feel - Examines how injection frequency affects hormone peaks and troughs, which has implications for the muscle-tendon mismatch discussed in this article.
Key References
1. Snyder PJ, Bauer DC, Ellenberg SS, et al. Testosterone Treatment and Fractures in Men with Hypogonadism. N Engl J Med. 2024;390:203-211. https://doi.org/10.1056/NEJMoa2308836
2. Snyder PJ, Kopperdahl DL, Stephens-Shields AJ, et al. Effect of Testosterone Treatment on Volumetric Bone Density and Strength in Older Men With Low Testosterone. JAMA Intern Med. 2017;177:471-479. https://doi.org/10.1001/jamainternmed.2016.9539
3. Lincoff AM, Bhasin S, Flevaris P, et al. Cardiovascular Safety of Testosterone-Replacement Therapy. N Engl J Med. 2023;389:107-117. https://doi.org/10.1056/NEJMoa2212321
4. Albright J, Lou M, Rebello E, et al. Testosterone Replacement Therapy Is Associated With Increased Odds of Achilles Tendon Injury and Subsequent Surgery. J Foot Ankle Res. 2023;16:78. https://doi.org/10.1186/s13047-023-00678-0
5. Testa EJ, Albright JA, Hartnett D, et al. The Relationship Between Testosterone Therapy and Rotator Cuff Tears, Repairs, and Revision Repairs. J Am Acad Orthop Surg. 2023;31(11):581-588. https://pubmed.ncbi.nlm.nih.gov/36898059/
6. Gould HP, Hawken JB, Duvall GT, Hammond JW. Testosterone Therapy Is Associated With Increased Odds of Quadriceps Tendon Injury. Clin Orthop Relat Res. 2024;482:179-190. https://doi.org/10.1097/CORR.0000000000002778
7. Grossmann M, Anawalt BD. Breaking News - Testosterone Treatment and Fractures in Older Men. N Engl J Med. 2024;390:267-268. https://doi.org/10.1056/NEJMe2313787
8. Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103:1715-1744. https://doi.org/10.1210/jc.2018-00229
9. Goto NA, Weststrate ACG, Verhaar MC, et al. Testosterone Replacement Therapy in Older Men: Skeletal Outcomes and Fracture Risk. Aging Male. 2026. https://doi.org/10.1080/13685538.2026.2655544
10. Morales A, Lunenfeld B. Investigation, Treatment and Monitoring of Late-Onset Hypogonadism in Males. Aging Male. 2002;5:74-86. https://doi.org/10.1080/tam.5.2.74.86
Medical Disclaimer
The information presented in this article is for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual circumstances vary significantly, and men considering or currently using testosterone replacement therapy should consult with a qualified healthcare provider familiar with their complete medical history. Do not start, stop, or modify any medical therapy based solely on information contained herein.
About ExcelMale.com
ExcelMale.com is the internet's most trusted, expert-moderated men's health community, with over 24,000 members and more than 20 years of archived discussions on testosterone replacement therapy, hormone optimization, sexual health, and men's wellness. Founded by Nelson Vergel, a chemical engineer turned patient advocate who has been on TRT for over 30 years, ExcelMale provides a rigorously evidence-based space where men can access real clinical information and connect with others navigating similar health journeys.
Nelson Vergel is the author of Testosterone: A Man's Guide and Beyond Testosterone. Visit www.ExcelMale.com to join the community and access the full archive of evidence-based men's health content.
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