Tendons In The Knee

By Alex Bigale, PTA

Tendons In The Knee

The knee is a complex joint with many components that must work together in synch to function properly.  This is why the knee is vulnerable to a multitude of injuries.  The knee is composed of bones, tendons, ligaments, muscles, cartilage, and other soft tissues. Tendons are structures that connect muscles to bones and many of those muscles cross the knee joint. Overall, the tendons of the knee help maintain its structure and stability.

Labeled illustration of human knee anatomy showing knee tendons.

Knee Tendon Anatomy

Tendons of the Knee

The front of the thigh has four quadriceps muscles that help make the knee extend or straighten.  They are the Vastus lateralis, Rectus femoris, Vastus Medialis Oblique, and vastus intermedius.  The hamstring muscles cross the backside of the knee and help to flex or bend the knee.  These are the biceps femoris, semitendinosus, and semimembranosus. The Sartorius and gracilis muscles are two muscles that originate at the hip and attach to the tibia that perform multiple functions, but flexion is their main movement.   There are also the gastroc muscles of the lower leg that cross the knee to help move the plantarflex the foot. 

Quadricep Tendons and the Knee 

The majority of tendon injuries that are related to knee pain affect the quadriceps and patellar tendons. This is mostly because the quads are responsible for directing the path of the patella (knee cap) over the trochlear groove as the knee flexes and extends. When there is an injury to a quadriceps tendon, that muscle may not engage as strongly as it should, and there becomes an imbalance of pull over the knee cap, which can cause pain and irritation.  

What does a Knee Tendon Injury Feel Like?

An injury to the knee tendon is characterized with a popping sensation followed with symptoms such as knee pain, swelling, bruising, and a noticeable loss of strength in the knee.

What is the most Common Injury to the Knee Tendons?

The most common tendon injury in the knee is a tear to the patellar tendon.  If the patellar tendon is completely torn, it may require surgery to repair the tendon.  Smaller tears to the tendon are need immobilization to protect the tendon while it is healing. Another common knee injury that causes pain in people who frequently run/jump or increase exercise intensity is called patellar tendonitis. This is inflammation of the tendon from repetitive or overuse.

Illustration of a patellar tendon in the knee. JOI Rehab

Grade 3 Tear to the Patellar Tendon

Grading Tendon Injuries

Grade 1: Mild with less than 5% of fibers torn.  A person with this grade of strain has some pain but typically does not lose strength.

Grade 2: Moderate amount of fibers torn. Typically has more severe pain, along with mild swelling and a noticeable loss of strength.

Grade 3:  Full-thickness tear of the fibers.  With this injury, a person usually experiences a “pop” sensation.  This is followed by severe pain, swelling, and bruising.  Because the muscle is under tension, it is common for a full tear to result in a bunched-up muscle and a gap or dent in the skin where the muscle was.  This is a severe injury and will most likely need surgical intervention to regain function.  

Can you still walk with Torn Tendon in the Knee?

This is dependent upon the grade of the injury. Most likely you will still be capable of walking with a loss of knee strength and stability of the knee. If you are experiencing knee pain you should always consult with your physician to avoid further injury.

What is the Fastest Way to Heal Tendons in the Knee?

  • Rest the injured muscle/tendon
  • Ice the injured area to reduce swelling
  • Compress the muscle/tendon with an elastic bandage
  • Elevate the injured area

This protocol will be effective for most tendon injuries (grade 1 or 2). A person can treat themselves with the RICE Protocol.  The focus will be to decrease swelling and pain associated with the tear to the tendon. For grade 3 tears or other injuries that do not resolve within a few days, you should contact your physician to see if other interventions are indicated for treatment. Additionally, Physical Therapy is needed in the healing process after a tendon injury in the knee.

By: Alex Bigale, PTA

Watch this video from The Jacksonville Orthopaedic Institute on Why Knee Pain Can’t Wait!

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