Tendon disorders can affect anyone, causing pain and limiting movement in the very tissues that help us stay active and mobile. Understanding what puts tendons at risk and how to protect them is essential for maintaining an active and healthy life.

What Are Tendon Disorders?

Tendon disorders are conditions that affect the fibrous cords connecting muscles to bones. Tendons are made of strong, smooth fibers that transfer force from muscles to bones, allowing joints to move. When tendons don’t function normally due to injury or repeated stress, they can cause significant discomfort and reduced ability to perform everyday activities.^[1]

There are two main types of tendons in the body: tendons without protective coverings, and tendons with sheaths that surround and lubricate them. When problems develop, they may involve inflammation, tissue breakdown, or damage to the protective covering around the tendon. These conditions can affect nearly any tendon in the body, though some locations are more commonly affected than others.^[1]

The terminology used to describe tendon problems has evolved over time. While the term tendinitis was traditionally used to describe tendon pain and swelling, suggesting inflammation as the main problem, research has shown that many chronic tendon conditions involve tissue breakdown rather than active inflammation. Because of this, the broader term tendinopathy is now preferred when describing painful tendon conditions, especially when the exact nature of the problem isn’t clear.^[2]

Tendinosis refers to a degenerative process where the structural protein called collagen breaks down in the tendon, causing it to lose strength and flexibility over time. This is different from tendinitis, which involves inflammation that may occur after an acute injury. Meanwhile, tenosynovitis describes inflammation of the thin membrane that surrounds certain tendons, causing swelling and restricted movement.^[1][2]

How Common Are Tendon Disorders?

Tendon disorders are quite common in the general population. More than thirty percent of all sports-related injuries involve tendons, but these conditions aren’t limited to athletes. Workplace activities, hobbies, and daily routines can all lead to tendon problems. In the United States, tendon injuries account for at least seven percent of all physician visits, making them a significant health concern.^[15]

Anyone can develop a tendon disorder, but they are especially common among people who perform repetitive movements regularly. This includes individuals engaged in certain sports, occupations requiring repeated motions, and those who suddenly increase their physical activity after long periods of rest. The shoulder, elbow, wrist, hip, knee, and ankle are the most frequently affected areas.^[7]

As people age, their risk for tendon problems increases. After age forty, tendons become less elastic and less able to tolerate stress. They are more prone to tearing and take longer to heal. This natural aging process affects the body’s ability to produce and maintain healthy collagen, the main structural component of tendons. Older adults may find that activities they once performed easily now cause persistent tendon pain.^[7]

What Causes Tendon Disorders?

Most tendon disorders develop when excessive mechanical stress is placed on a tendon over time. When someone repeats the same movement frequently without adequate rest, small tears can form in the tendon fibers. Think of it like a rope that becomes frayed after being pulled and twisted repeatedly. These tiny injuries accumulate, and if the tendon doesn’t have enough time to heal, the damage worsens.^[5]

When tendons are overused, blood flow to the affected area may decrease, limiting the delivery of oxygen and nutrients needed for repair. The body tries to heal the damage, but in chronic cases, the healing process goes wrong. Instead of producing healthy tendon tissue, the body may create scar tissue or calcium deposits. These abnormal changes weaken the tendon and make it more vulnerable to further injury.^[1][5]

Sudden, forceful movements can also damage tendons. A quick pull or twist during physical activity or an accident can cause acute tendon injury. In severe cases, the tendon may partially or completely tear away from the bone, a condition called tendon rupture. People often hear or feel a popping sound when this happens, followed by immediate pain and inability to use the affected joint.^[2]

Certain underlying medical conditions increase the risk of tendon problems. Diabetes can affect tendon health by altering tissue structure and reducing healing capacity. Rheumatoid arthritis, an autoimmune disease that causes joint inflammation, can also damage tendons. Gout, which causes crystal deposits in joints, may irritate nearby tendons. Even infections can occasionally lead to tendon inflammation.^[7]

Some medications have been linked to tendon damage. Certain antibiotics in the fluoroquinolone family, drugs called statins used to lower cholesterol, and corticosteroids can weaken tendons and make them more prone to injury. While these side effects are relatively rare, patients taking these medications should be aware of the potential risk.^[2][7]

Risk Factors for Developing Tendon Problems

Several factors increase a person’s likelihood of developing tendon disorders. Performing repetitive activities day after day is one of the strongest risk factors. Athletes who train intensely without adequate rest periods put tremendous strain on their tendons. Similarly, workers whose jobs require them to make the same motion hundreds or thousands of times may gradually damage their tendons.^[5]

Examples of repetitive activities that commonly lead to tendon problems include typing on a computer, using a mouse for extended periods, painting walls or ceilings, gardening, woodworking, shoveling snow, and playing sports like tennis, golf, basketball, or baseball. Even scrubbing floors or sewing can strain tendons if done for long periods without breaks.^[2][7]

Poor posture and improper technique during physical activities place extra stress on tendons. When joints aren’t properly aligned, some tendons must work harder to compensate, leading to overload. Athletes who use incorrect form when throwing, hitting, or jumping are especially vulnerable. Similarly, workers who maintain awkward positions for long periods may strain their tendons without realizing it.^[1][2]

Other risk factors include inadequate flexibility, lack of muscle strength, muscle imbalances where some muscles are much stronger than others, and abnormalities in posture or the way someone walks. Foot deformities or wearing inappropriate footwear can increase stress on leg and foot tendons. Being overweight places additional load on tendons, particularly in the lower body. Smoking has also been identified as a risk factor, possibly because it affects blood flow and tissue healing.^[2][5]

Common Symptoms of Tendon Disorders

Pain is the primary symptom of tendon disorders. This pain typically occurs at or near the point where the tendon attaches to bone. The discomfort often gets worse when the affected tendon is stretched or when the muscle connected to it contracts. For example, someone with Achilles tendon problems will feel pain when standing on tiptoes or pushing off while walking or running.^[5][7]

The pain may be described as a dull ache that persists throughout the day, or it might be sharp and sudden with certain movements. In early stages, pain may only occur during or after activity. As the condition progresses, pain may be present even at rest. Touching or pressing on the affected tendon often causes tenderness and discomfort.^[2][3]

Swelling around the affected tendon is another common symptom. The area may appear puffy or feel thicker than normal. In some cases, the skin over the tendon becomes warm to the touch or changes color, appearing red, purple, or darker than the surrounding skin. These signs suggest inflammation or irritation in the tendon or its surrounding tissues.^[7]

Stiffness frequently accompanies tendon disorders. The affected joint may feel tight, especially first thing in the morning or after periods of rest. This stiffness can limit how far the joint can be moved, reducing flexibility and range of motion. Simple tasks like reaching overhead, gripping objects, or climbing stairs may become difficult or painful.^[2]

Some people experience crackling, popping, or grating sensations when moving the affected joint. This occurs because the damaged tendon no longer glides smoothly through its surrounding tissues. In severe cases, particularly when a tendon has ruptured, there may be a visible bulge or depression in the affected area, along with weakness or complete inability to move the joint.^[2][7]

Where Do Tendon Disorders Most Often Occur?

Tendon disorders can develop anywhere in the body, but certain locations are more commonly affected. In the shoulder, problems frequently involve the tendons of the rotator cuff, a group of four tendons that help rotate the upper arm bone and lift the arm. The biceps tendon, which runs along the front of the shoulder, is another common site of trouble. Shoulder tendon problems often result from overhead activities or repeated lifting.^[1][2]

Elbow tendon disorders include lateral epicondylitis, commonly known as “tennis elbow,” which affects the outer side of the elbow where forearm tendons attach. Medial epicondylitis, or “golfer’s elbow,” affects the inner side of the elbow. Both conditions cause pain that may radiate down the forearm and difficulty with gripping or lifting objects.^[1][4]

In the wrist and hand, several tendons are vulnerable to injury. Flexor tendons on the palm side and extensor tendons on the back of the hand and wrist can become inflamed or damaged. De Quervain’s disease specifically affects the tendons at the base of the thumb, causing pain with thumb and wrist movement. Trigger finger is a condition where a tendon in the finger becomes inflamed and catches, making the finger lock or snap when bending.^[1][4]

The knee is home to the patellar tendon, which connects the kneecap to the shin bone. This tendon is stressed during jumping and running activities, leading to a condition sometimes called “jumper’s knee.” In the ankle and foot, the Achilles tendon connecting the calf muscles to the heel bone is one of the most commonly injured tendons in the body. The posterior tibial tendon, which supports the arch of the foot, and peroneal tendons on the outside of the ankle are also frequent sites of problems.^[2][4]

How Tendon Disorders Affect the Body

Understanding what happens inside an injured tendon helps explain why these conditions can be so persistent. Normal, healthy tendons are composed of tightly organized bundles of collagen fibers. These fibers are arranged in parallel lines, giving the tendon great strength while allowing some flexibility. Special cells called tenocytes maintain the tendon by producing new collagen and breaking down old or damaged tissue.^[15]

When a tendon is overused, the normal balance between tissue breakdown and repair is disrupted. The repeated stress causes small tears in the collagen fibers, much like how a rope frays when pulled repeatedly. Initially, the body responds with inflammation, sending immune cells and fluid to the area in an attempt to heal the damage. This inflammatory response causes pain, swelling, and warmth in acute tendon injuries.^[1]

If the stress continues without adequate rest, the tendon cannot complete the healing process. The organized collagen structure becomes disorganized and tangled. The tendon may thicken and become bumpy or irregular in texture. Over time, the collagen degenerates, becoming weaker and less elastic. This degenerative process is characteristic of chronic tendinosis and occurs even in the absence of active inflammation.^[1][2]

In tendons with protective sheaths, the lubrication system can malfunction. The membrane surrounding the tendon may not produce enough lubricating fluid, or the fluid quality may be poor. This leads to increased friction as the tendon moves, causing inflammation of the sheath itself—a condition called tenosynovitis. The inflamed sheath becomes swollen and may develop fibrous tissue that further restricts tendon movement.^[1]

Calcium deposits sometimes form in chronically damaged tendons. These hard deposits develop when the body’s repair mechanisms go awry, depositing calcium salts in the tendon tissue. The deposits can cause additional pain, stiffness, and mechanical irritation. Blood supply to the damaged area may be reduced, which slows healing since tendons naturally have limited blood flow compared to other tissues.^[5]

Without treatment, chronic tendon problems can lead to progressive weakness. The affected muscle may begin to waste away, a process called atrophy, because pain and reduced function limit its use. In severe cases, the weakened tendon may completely tear or rupture, requiring more intensive treatment and a much longer recovery period. Chronic pain can also lead to altered movement patterns as the body tries to avoid discomfort, potentially causing problems in other joints and muscles.^[2]

Preventing Tendon Disorders

While not all tendon disorders can be prevented, several strategies can significantly reduce the risk of injury. Proper warm-up before exercise is essential. Warming up gradually increases blood flow to muscles and tendons, making them more pliable and less prone to injury. Light aerobic activity followed by gentle stretching prepares the body for more intense physical demands.^[26]

Taking regular breaks during repetitive activities gives tendons time to recover. Workers who type, use tools, or perform assembly line tasks should pause periodically to rest their hands, wrists, and arms. Athletes should incorporate rest days into their training schedules rather than pushing through fatigue. Gradually increasing the intensity and duration of activities, rather than making sudden changes, allows tendons to adapt to new demands.^[2][26]

Maintaining good posture during daily activities reduces unnecessary stress on tendons. Ergonomic workstation setup is important for people who spend hours at computers. Chairs, desks, keyboards, and monitors should be positioned to keep joints in neutral positions. Using proper form and technique during sports and exercise is equally important. Athletes and fitness enthusiasts should consider working with coaches or trainers to ensure their movement patterns don’t place excessive strain on tendons.^[1]

Wearing appropriate footwear provides support and cushioning that protects leg and foot tendons. Shoes should fit properly, provide adequate arch support, and be suitable for the specific activity. Athletic shoes designed for running, for example, offer different support than those made for tennis or basketball. Replacing worn-out shoes prevents problems caused by inadequate cushioning or support.^[5]

Building and maintaining muscle strength and flexibility helps protect tendons. Strong muscles can better absorb forces during activity, reducing the load on tendons. Flexibility allows joints to move through their full range of motion without placing excessive tension on tendons. A balanced exercise program that addresses all major muscle groups and includes both strengthening and stretching exercises is ideal.^[2]

Staying hydrated supports overall tissue health, including tendons. Water helps maintain the cushioning properties of tissues surrounding tendons and supports the delivery of nutrients needed for tissue maintenance. Eating a balanced diet rich in nutrients that support collagen production and tissue health may also contribute to tendon resilience.^[2]

Listening to your body and addressing minor aches promptly can prevent minor issues from becoming major problems. When you feel persistent discomfort or notice changes in how a joint moves, giving that area rest and seeking guidance from a healthcare provider can prevent progression to more serious tendon damage. Early intervention is far more effective than trying to treat long-standing tendon problems.^[5]