Patellar Tendon Rupture – Tear of the Patellar Tendon in the Knee Joint

Tendons act as a link between muscles and the bones that form joints. They provide the connection that transmits the pulling force of the muscles to the skeletal system. 

This enables movement, allowing you to, for example, raise an arm or straighten a leg. Injuries to the tendons therefore typically cause restricted movement and pain.

The patellar tendon connects the lower part of the kneecap to the lower leg. Together with the quadriceps tendon, it enables the knee joint to extend. If the patellar tendon is injured or tears, the knee joint can no longer extend.

The patellar tendon is a ligament that connects the lower tip of the kneecap to the shinbone @ designua /AdobeStock

What happens during a patellar tendon rupture?

A patellar tendon rupture occurs after the tendon has been overused. This often happens during sports, which is why a patellar tendon rupture is also considered a classic sports injury. 

Men between the ages of 20 and 50 are particularly prone to patellar tendon ruptures. In many cases, the patellar tendon is already damaged, which increases the risk of a partial tear or a complete rupture.

What are the causes of a patellar tendon rupture?

A patellar tendon rupture rarely occurs spontaneously. As a rule, one of the following causes can be identified:

• Overuse during sports
• Accidents
• Metabolic disorders, such as diabetes mellitus
• Weakness of the connective tissue
• Injections into the tendon
• Secondary injuries to the tendon following surgery

What are the symptoms of a patellar tendon rupture?

A patellar tendon rupture is associated with localized or radiating pain in the knee area. At the same time, there is usually a loss of strength in the joint. It is no longer possible to straighten the knee joint. 

Bruising (hematoma) and swelling in the knee joint may also occur. Often, the kneecap (patella) becomes dislocated because it is no longer connected to the patellar tendon on the lower leg. In this case, it is advisable to see a doctor.

Diagnosis of a Patellar Tendon Rupture

Specialists have various diagnostic procedures at their disposal to confirm a “patellar tendon rupture.” In the case of a patellar tendon rupture, the clinical presentation alone can often confirm the diagnosis. This includes findings such as patellar displacement.

On an X-ray, the doctor can then confirm the suspected tendon tear: Here, a high-riding patella is usually noticeable, as the intact quadriceps tendon pulls the now-unrestricted patella upward.

On an ultrasound, the patellar tendon rupture specialist can determine whether the tear is partial or complete.

Using magnetic resonance imaging (MRI), the doctor can check for further damage around the knee joint. They examine whether there is accompanying joint effusion.

In the case of a patellar tendon tear, the knee is severely swollen and painful; if only part of the tendon is torn, the symptoms are less severe @ PixelGallery /AdobeStock

Treatment Options for a Patellar Tendon Tear

Treatment for a patellar tendon tear can be conservative or surgical, depending on the severity. 

Conservative treatments for a patellar tendon tear include:

• Physical therapy
• Rest for 6 to 8 weeks
• Pain medication

However, conservative treatment is only an option for a partial patellar tendon tear. If there is a complete patellar tendon tear, surgery is unavoidable.

During patellar tendon surgery, the specialist reattaches the ends of the torn tendon to one another. Doctors refer to this as a tendon suture. 

A McLaughlin wire cerclage is used as a supportive measure. This additional fixation relieves stress on the tendon and facilitates healing and early rehabilitation through physical therapy.

Following accidents, the knee joint and bone structures at the tendon insertion site may also be injured. In such cases, the doctor may additionally stabilize the tendon using screw or tension band osteosynthesis. These involve screw fixations in the area of the knee joint that stabilize the knee and relieve pressure on the tendon.

The prognosis for a patellar tendon tear

In most cases, a patellar tendon rupture responds well to treatment. Tendon function is usually fully restored after surgery. 

Early intervention and physical therapy or appropriate exercise after surgery are important. In most cases, a full return to sports is possible after a few months to a year, provided there is adequate recovery time. 

However, following conservative treatment for a partial tear, you must expect a permanent loss of strength in the knee joint. A recurrent patellar tendon tear is also possible.

As with any surgery, complications can occur in rare cases following a patellar tendon tear:

• Bleeding
• Infections
• Wound healing disorders: These are particularly common following accidents involving concurrent injuries to the bones and articular cartilage. 

In addition, adhesions in the tendon and tendon shortening may occur during the healing process. Both can restrict range of motion in the knee joint.

Specialists for a Patellar Tendon Rupture

A patellar tendon rupture is classified as a sports injury. Therefore, the following departments are responsible:

• Sports Medicine
• Orthopedics 
• Trauma Surgery 

It is important that you seek treatment at a specialized center. The surgeon’s experience with patellar tendon ruptures is also a significant factor in the outcome of treatment. Specialists in patellar tendon ruptures include sports medicine physicians, orthopedic surgeons, and trauma surgeons.

Conclusion

A patellar tendon rupture is a serious injury to the knee joint that often results from a sudden, sharp pain during sports such as basketball, skiing, or tennis, as well as from a blow to the knee or rapid changes in direction. A physical examination usually reveals a torn tendon, a patella displaced upward at its tip, and limited extension in the knee joint, since the patellar tendon connects the patella to the tibia.

Depending on the severity of the patellar tendon tear, either conservative treatment or surgical treatment is used, as sufficient stability of the knee joint is crucial for restoring function.

Treatment for a patellar tendon tear includes physical therapy, targeted exercises, and muscle strengthening to improve the function of the quadriceps and surrounding tissues.

Healing often takes 6 to 9 months, with the weeks following surgery being critical for a safe return to a state where the knee can once again bear weight.