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Patella Tendon Rupture Causes, Symptoms & Treatment Options

Q: Can untreated patellar tendonitis lead to a rupture?

Yes. Chronic patellar tendonitis weakens the tendon and significantly increases the risk of rupture if proper patellar tendonitis treatment is not followed.

Causes, Symptoms & Treatment

Tendons are strong, dense, fibrous tissues that connect muscles to bones. The patellar tendon connects the kneecap (patella) to the shinbone (tibia) and works together with the quadriceps muscles to straighten the knee. A patella tendon rupture is a serious injury that disrupts this mechanism, making normal walking, jumping, and athletic movement difficult or impossible. Patellar tendon ruptures commonly occur after a fall, a direct blow to the knee, or excessive force placed on the tendon during jumping or landing activities. In many cases, long-standing patellar tendonitis (also known as jumper’s knee or tendonitis in the knee) weakens the tendon and increases the risk of rupture.

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Overview
Causes
Symptoms
When to see a doctor
Surgical Treatment
Recovery

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Overview

The patellar tendon plays a critical role in knee extension(straightening the knee) and stability. Its proper function is essential for activities such as running, jumping, climbing stairs, and landing from a jump. When a patellar tendon rupture occurs, the knee loses its ability to actively straighten, resulting in significant functional limitation.

This injury is most often seen in younger, active individuals and athletes but can occur in anyone with underlying tendon weakness. Early diagnosis and treatment are crucial to restoring knee strength and preventing long-term disability.

What causes Patella Tendon Rupture?

A patella tendon rupture occurs when the tendon is subjected to forces greater than it can tolerate, especially if it has been weakened over time.

1. How the Injury Happens

Patellar tendon rupture most commonly occurs during:

Sudden jumping or explosive takeoff movements
Landing forcefully from a jump
Abrupt changes in direction
Falls that cause the knee to bend suddenly under load

These actions place intense stress on the patellar tendon, leading to tearing or complete rupture.

2. Causes and Risk Factors

Several factors increase the likelihood of a patellar tendon rupture:

Chronic patellar tendonitis, which weakens the tendon fibers
Repetitive stress from jumping sports
Poor flexibility or muscle imbalances
Previous knee injuries

Athletes under the age of 40 are particularly susceptible, especially if patellar tendonitis treatment has been delayed or incomplete.

Sports Commonly Associated with Patella Tendon Ruptures

Patellar tendon ruptures are more common in sports that involve repetitive jumping, sprinting, and sudden stops, including:

Running – repetitive loading of the knee during acceleration and deceleration
Basketball – frequent jumping and hard landings
Soccer – explosive movements and rapid direction changes
Volleyball – repeated jumping and overhead attacks

Symptoms

Athletes who experience a patella tendon rupture often report a sudden tearing or popping sensation in the knee at the time of injury. This injury typically results in immediate loss of the ability to straighten the knee.

Common symptoms include:

Severe pain and swelling just below the kneecap
Inability to straighten the knee or perform a straight leg raise
Upward movement of the kneecap, as it is no longer anchored to the shinbone
Difficulty walking or bearing weight
Bruising around the knee and lower thigh

These symptoms are more severe than those seen with patellar tendonitis, which usually presents with gradual pain rather than sudden loss of movement.

When to see a doctor

Any athlete or individual experiencing sudden knee pain, swelling, or inability to straighten the leg after an injury should seek immediate medical attention. Early evaluation is critical to confirm whether a patellar tendon rupture has occurred and to plan the appropriate treatment.

During the examination, your doctor will:

Inspect the knee for swelling and bruising
Palpate the tendon for defects
Ask you to attempt to straighten your leg

Diagnostic Imaging

To confirm the diagnosis, your doctor may order:

X-rays to assess the kneecap position and rule out fractures
MRI scans to evaluate the extent of the tendon injury and identify related damage

Surgical Treatment

Most patella tendon ruptures require surgical repair to restore normal knee function. Surgery involves reattaching the torn tendon to the kneecap and is typically performed as an outpatient procedure.

Early surgery is strongly recommended because:

Scar tissue forms quickly after injury
The tendon can shorten over time, making repair more difficult
Delayed treatment can negatively affect strength and recovery

When performed promptly, surgical repair has a high success rate, allowing most athletes to return to sports and full activity.

Recovery

Recovery after patellar tendon rupture surgery is a structured and gradual process. Most athletes require six to twelve months before returning to full athletic activity.

Recovery typically includes:

Immobilization with a splint or cast for 4–6 weeks
Gradual progression of knee motion
Strengthening exercises through physical therapy
Functional training for sports-specific movements

Your doctor and physical therapist will closely monitor your progress to ensure safe healing and prevent reinjury.

Reviewed By

Jay Kimmel

Dr. Jay Kimmel is a board-certified orthopedic surgeon specializing in sports medicine, arthroscopic surgery, and shoulder and knee disorders. He completed his orthopedic training at New York-Presbyterian/Columbia University Medical Center and a Sports Medicine Fellowship at Temple University.

Dr. Kimmel previously served as the Director of the Connecticut Sports Medicine Institute at Saint Francis Hospital and has held faculty appointments as Clinical Assistant Professor in the Departments of Orthopedics and Family Medicine at the University of Connecticut. He has extensive experience caring for athletes as a team physician for high school and collegiate programs and continues to teach in the athletic training departments at Westfield State University and Springfield College.

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