Tendon Injuries: Causes, Symptoms, and Treatment of Muscle and Tendon Injuries

Tendons are connective tissue structures that connect muscles to bones. Their function is to transmit the force generated by the muscle to the corresponding bone. This, in turn, is the basis for all joint movement and thus enables human locomotion. Thus, tendons are part of the human “musculoskeletal system” and must sometimes withstand very high loads. 

 
Tendons connect muscles to bones and enable movement @ BigBlueStudio /AdobeStock

If a tendon becomes diseased or injured, it loses its ability to function, and the affected muscle loses contact with the bone.

There are chronic tendon disorders, which are often caused by inflammation or overuse of the muscle. These are also referred to as degenerative disorders, which are primarily caused by wear and tear. The risk of degenerative tendon disorders increases with age.

However, the most common condition—which will be discussed in more detail below—is acute (sudden and accident-related) tendon injuries. These occur

• under heavy strain,
• unfamiliar, rapid, and jerky movements, or
• direct trauma.

The latter refers, for example, to a laceration with a clean severing of the tendon, which is, however, rather rare.

Even though—and especially since—acute tendon injuries are more common than chronic ones, it should be emphasized here that in many cases, a combination of acute and chronic injuries is present. For example, a tendon rupture can occur in tendons that are already degeneratively damaged following relatively minor force and a minor accident. Consequently, the risk of a tendon injury resulting from an accident also increases with age. The exact location of the injury plays a decisive role, as different forms of treatment are necessary depending on the type and severity of the injury.

As a rule, tendon injuries are caused by direct force. Tendon lacerations are usually the result of injuries caused by a sharp object. However, the most common type of tendon injury is a tendon tear or partial tear. This disrupts the connection between the muscle and the bone, thereby limiting muscle function—that is, the muscle’s ability to support the bone during movement.

A tendon rupture occurs particularly frequently due to sudden overexertion and overstretching. A muscle tear, muscle fiber tear, or muscle strain can also result from repetitive strain or trauma. Athletes who subject their bodies to prolonged strain—for example, during long hikes in the mountains—are particularly susceptible. However, an injury can also result from a fall or a twisting of the joint. Spontaneous tendon tears can occur when pre-existing damage—such as that associated with a rheumatic disease—is already present. This is particularly true for older adults, whose tendons show greater wear and tear and are therefore more prone to tearing.

A common cause of tendon-related symptoms is injury resulting from excessive or improper strain. External factors can lead to overstretching, ruptures, or tendon tears. Among the most common tendon injuries are tears of the biceps and Achilles tendons. Other typical tendon tears involve the extensor or flexor tendons of the hand, as well as the patellar and quadriceps tendons.

The Achilles tendon is the strongest tendon in the human body @ Sebastian Kaulitzki /AdobeStock

For those affected, a tendon injury is usually accompanied by pain and swelling. In addition, the function of the muscle and the affected limb is impaired. 

The most common symptoms resulting from tendon injuries include pain in the affected area, as well as instability and loss of function in the respective joint. For example, a torn biceps tendon in the forearm or a torn Achilles tendon often causes a sudden, stabbing pain; as the injury progresses, a large bruise and a visible or palpable indentation appear at the affected site. In the case of tears in the extensor or flexor tendons of the hand, pain, swelling, and bruising may occur. In addition, the affected fingers can no longer be moved properly.

Because tendons have poorer blood supply compared to other tissues, the healing process often takes quite a long time. Furthermore, many people do not adhere to the necessary rest and recovery measures. As a result, the injury cannot heal completely, leading to chronic tendon problems. This is particularly true for tendons that are under heavy strain, such as the Achilles tendon.

The blood supply to tendons comes from the vessels in the muscles, bones, and tendon sheaths, and is poor compared to other body tissues. Furthermore, tendons have few cells, which divide only slowly and therefore take a long time to heal when injured.

Often, the nature of the injury and the symptoms described by the patient are already indicative of a tendon injury. Typical signs include sudden, stabbing pain as well as visible swelling or bruising. In most cases, the patient is no longer able to perform certain movements.

In the case of a rupture of the tendons near the knee joint, for example, this loss of function manifests as the patient’s inability to straighten the knee. Clinical tests are then used to specifically assess the affected movements. To confirm the initial diagnosis, an ultrasound examination or magnetic resonance imaging (MRI) is helpful. Both procedures provide reliable results when it comes to diagnosing tendon tears.

Do you suspect you have a tendon injury? If so, contact an appropriate specialist as soon as possible. These include orthopedic surgeons and trauma surgeons. These doctors often specialize in specific areas of the body; for example, there are surgeons who specialize in the knee or in the foot and ankle.

The best possible treatment for a tendon injury depends largely on the tendon involved. Complete healing of a torn tendon usually requires surgery. Only partial tears of the tendon are treated conservatively. While this type of treatment involves the use of a special splint or orthosis, surgery is performed to reattach the severed ends of the tendon. Alternatively, the tendon is attached directly to the bone using a special suturing technique to provide greater stability. To relieve stress on the suture and further secure the connection, a cerclage (wrapping) made of wire and suture thread or additional fixation using screws is often used.

The majority of tendon injuries heal well, and joint function is restored. However, complications and re-tears can also occur.

According to study results, conservative treatment carries a slightly increased risk of the tendon tearing again. This is also referred to as a recurrence or re-rupture. When deciding for or against surgery, the patient’s specific needs should therefore also be taken into account.

If the patient decides to undergo surgery, they have the choice between open and minimally invasive procedures. Open procedures provide a very clear view of the affected area and thus offer the best conditions for direct suturing. This is particularly advantageous for older tears; however, there is also a higher risk of scarring, adhesions, and impaired wound healing. 

Recently occurred and simple ruptures should therefore preferably be treated using minimally invasive techniques. This involves using a device specifically developed for this purpose, which allows long instruments to be inserted through the skin into the joint via small incisions. These instruments allow the torn tendon ends to be pulled together and secured with thick sutures. These sutures can then be easily knotted together, thereby stabilizing the tendon ends. Wound healing complications are very rare due to the small incisions.

1. How does a tendon injury occur?
Tendon injuries are usually caused by sudden overexertion, jerky movements, or direct impact—often during sports training. Depending on the severity, this can result in overstretching, a partial tear, or a complete tendon rupture.

2. How is a tendon injury diagnosed?
The diagnosis is made through a thorough medical history, followed by a clinical examination. Imaging techniques such as ultrasound or magnetic resonance imaging (MRI) are used to accurately assess the type and extent of the injury.

3. What treatment options are available?
Depending on the location and severity, treatment may involve conservative management with immobilization and physical therapy, or surgical reconstruction of the tendon ends. The goal is to fully restore function.

4. What is the healing process and follow-up care like?
The healing time varies depending on the severity and the affected limb. Targeted follow-up care through sports orthopedics and physical therapy is crucial for restoring mobility and preventing re-injury.