Meniscus tears happen when the rubbery, C-shaped cartilage cushioning your knee joint gets damaged, either from a sudden twisting force or from gradual wear over time. These two pathways, acute injury and degeneration, account for nearly all meniscus tears, but a range of factors from body weight to occupation to anatomy can raise your risk significantly.
Sudden Twisting Under Load
The most common acute cause is forcefully twisting or rotating your knee while it bears weight. Picture planting your foot and pivoting hard, decelerating suddenly while changing direction, or getting tackled with your foot fixed to the ground. These movements create shearing forces across the meniscus that exceed what the tissue can absorb. Deep squatting, heavy lifting, and even kneeling can generate enough force to tear a healthy meniscus if the angle and load are right.
ACL injuries and meniscus tears frequently occur together. When the ACL ruptures, the resulting instability in the knee places enormous stress on the meniscus. In cases of chronic ACL injury, up to 83% of patients also have a meniscus tear. The instability essentially leaves the meniscus doing a job it was never designed to handle alone.
Age-Related Degeneration
Not every meniscus tear involves a dramatic moment. As you age, the cartilage tissue loses water content and becomes stiffer, more brittle, and less able to absorb repetitive stress. Years of routine mechanical loading gradually break down the collagen structure. At some point, an everyday movement like stepping off a curb or getting out of a chair can be enough to cause a tear in tissue that was already compromised.
The medial (inner) meniscus is especially vulnerable to degenerative tears. It’s more firmly attached to the surrounding joint capsule and less mobile than the lateral (outer) meniscus, which means it absorbs more repetitive stress in the same spot. The lateral meniscus has looser attachments and more freedom to shift slightly under load, which helps protect it from this kind of gradual damage.
Making things worse, the meniscus has very limited blood supply once you reach adulthood. Only the outer third receives meaningful blood flow, so the inner portions have almost no ability to repair accumulated damage. Small injuries simply persist and compound over time.
Body Weight and Obesity
Carrying extra weight dramatically increases your risk. Every step you take transmits two to three times your body weight through your knees, so even moderate weight gain adds up over thousands of daily steps. The numbers are striking: people with a BMI of 40 or higher face roughly 15 times the odds of needing meniscal surgery (for men) and 25 times the odds (for women) compared to people at a normal weight. Even being moderately overweight raises the risk to a statistically significant degree in both men and women.
Sports That Stress the Knee
Sports involving cutting, pivoting, and rapid deceleration carry the highest risk. Professional soccer players experience meniscus injuries at a rate of about 0.45 per 1,000 hours of play, and a large meta-analysis found that playing football at a professional level carries more than five times the risk of meniscal damage compared to the general population. Basketball, tennis, skiing, and rugby follow similar patterns, with any sport that demands quick changes of direction placing repeated rotational stress on the knee.
In basketball, athletes who undergo meniscus surgery often return to comparable levels of agility and jumping ability, but their overall career length tends to be shorter than that of uninjured peers. The meniscus never fully returns to its original resilience.
Occupational Risk Factors
Your job can be just as damaging as sports. A systematic review and meta-analysis identified several workplace activities with strong links to meniscal tears. Kneeling on the job roughly doubles the risk. Squatting for more than an hour a day shows a similar doubling. Climbing more than 30 flights of stairs daily increases risk by about 2.3 times, and regularly lifting loads of 10 kilograms (22 pounds) or more raises risk by roughly 60%.
Two occupations stand out. Coal miners face more than five times the risk of meniscal damage, likely due to the combination of kneeling, squatting, and heavy lifting in confined spaces. Floor layers, who spend their workdays on their knees, face about double the general risk. These findings explain why meniscus tears in workers often look different from athletic injuries: they tend to be degenerative in nature, building slowly from years of repetitive stress rather than a single traumatic event.
Anatomical Variations
Some people are born with a meniscus that’s shaped differently. A discoid meniscus is larger, thicker, and more disc-shaped than the normal crescent. Its collagen fibers are also organized abnormally at a structural level. Because of its unusual size and reduced stability, a discoid meniscus is prone to tearing, pain, and mechanical symptoms like catching or locking. This condition primarily affects the lateral meniscus and is often diagnosed through MRI or during arthroscopic surgery.
Types of Tears and What Drives Them
The pattern of a tear often reflects its cause. Longitudinal tears run along the length of the meniscus and separate the inner edge from the outer rim. When a longitudinal tear is severe enough, the inner portion can flip into the center of the joint like a bucket handle, causing the knee to lock. These bucket-handle tears typically result from acute trauma in younger patients.
Horizontal tears split the meniscus into upper and lower halves, sliding between the collagen bundles rather than cutting across them. These are the classic degenerative pattern, appearing most often in older adults. Radial tears cut perpendicularly across the meniscus from the inner edge outward, severing the circumferential fibers that give the meniscus its ability to distribute load. This makes radial tears particularly damaging to knee function.
How Meniscus Tears Are Identified
Diagnosis usually starts with a physical exam. The McMurray test, where a clinician rotates and extends your knee while feeling for a click or pain, is one of the most commonly used assessments. Its accuracy varies depending on which meniscus is affected: about 61% for medial tears and roughly 92% for lateral tears. Because the physical exam alone can miss a significant number of medial meniscus injuries, MRI is frequently used to confirm the diagnosis and identify the specific tear pattern.
Reducing Your Risk
You can lower your chances of a meniscus tear through a few practical strategies. Maintaining a healthy body weight removes one of the most significant modifiable risk factors. Strengthening the muscles around your knee, particularly the quadriceps and hamstrings, helps absorb forces that would otherwise go directly through the meniscus.
Neuromuscular training programs that combine balance work, agility drills, plyometrics, and exercises like lunges and knee bends improve how well your body controls knee position during dynamic movements. These programs train your muscles to react faster and stabilize the joint during the cutting and pivoting motions that cause acute tears. For people in high-risk occupations, using knee pads, taking breaks from prolonged kneeling or squatting, and using proper lifting mechanics can meaningfully reduce cumulative stress on the meniscus over a career.