Anterior Cruciate Ligament (ACL) Tear


  • The ACL is located in the middle of the knee joint
  • Connects the lower leg bone to the thigh bone
  • Stabilizes the knee by preventing the tibia (shin bone) from sliding too far forward at the knee


  • Most ACL tears occur in non-contact injuries
    • Planting the foot and cutting
    • Pivoting
    • Landing on a straight leg
    • Making a sudden stop
  • ACL can be injured from direct trauma to the knee

Risk Factors

  • Sex
    • Typically females have a higher incidence than males
  • Muscle imbalances and week lower extremity muscles
  • Playing sports that require sudden changes of direction and deceleration
  • Incorrect technique for cutting, planting pivoting, jumping


  • A "popping" sound may sometimes be heard
  • Moderate pain
  • Gradual increase of swelling
  • Difficulty walking on the affected leg
  • Knee may feel "unstable"


  • An orthopedic doctor will typically provide a diagnosis
    • Included in a physical examination are special tests
  • MRI
    • Uses magnetic waves to show structures inside the knee
  • Arthroscopy
    • Thin "scope"/carnera inserted into the knee through small portals (incisions) to physically look at the structures inside


  • Physical Therapy Care
    • Recommended if you forgo surgery and will be necessary following surgery
    • Includes range of motion exercise, strengthening and stretching to restore function to prior level
    • Inclusive of sport specific training for appropriate patients

  • Surgery
    • May be needed to fully restore knee function and return to sport following physical therapy
  • Knee Brace
    • May be needed while recovering from the injury or surgery
    • Typically worn in sport activity


  • Precautions can be taken to avoid or decrease the chance of an ACL tear
  • When jumping , landing, turning and pivoting , knees need to be bent, not straight
  • Incorporate adequate warm up to prepare the knee for sports
  • Sport specific plyometrics can be used to train and strengthen the leg muscles to endure movements required for sport
  • Maintaining strength and flexibility of lower extremity, particularly quadriceps and hamstrings

Knee Anatomy

  • Articular Cartilage:
    • Lines the boney surfaces
    • Decreases the friction within the joint
  • Medial Collateral Ligament (MCL)
    • Runs down inside of knee joint
    • Connects femur to tibia
    • Limits sideway motion of knee
  • Lateral  Collateral Ligament (LCL)
    • Runs down outside of knee joint
    • Connects femur to fibula and tibia
    • Limits sideway motion of knee
  • Anterior Cruciate Ligament (ACL)
    • Connects femur and tibia in center of knee
    • Limits rotation and forward motion of the tibia
  • Posterior Cruciate Ligament
    • Connects femur and tibia in center of knee
    • Limits backward  motion of tibia
  • Meniscus
    • Cartilage on your tibia
    • Absorbs shock in the knee joint