Tendons In The Knee

By Alex Bigale, PTA

Tendons of the knee build stability.

Knee Tendons illustration.

Structures of the Knee

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

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 back side 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 plantar flex the foot. 

Common Injuries Involving The Tendons

The majority of tendon injuries that are related to knee pain are ones that affect the quadriceps and patellar tendon. 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.  Another common knee injury that causes pain in people who frequently run/jump or have an increase in exercise intensity is called patellar tendonitis. This is inflammation of the tendon from repetitive or overuse.

Grading Tendon Injuries

  • Grade 1: Mild with less that 5% of fibers torn.  A person with this grade of strain has some pain, but typically does not lose an strength.
  • Grade 2: Moderate amount of fibers torn. Typically has more severe pain, along with mild swelling and 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 very serious injury and will most likely need surgical intervention to regain function.  


For the majority of tendon injuries (grade 1 or 2) a person can treat themselves with the RICE program.

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

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.

JOI Fracture and Injury Care

JOI Physicians are currently offering ASAP Fracture care. Make an appointment by calling (904)JOI-2000. This is a new option for patients who would like to avoid the emergency room if they have suffered a fracture or soft tissue injury. To learn more about this service, read this article about fracture and injury care.

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By: Alex Bigale, PTA

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