The Knee

Bones of the Knee Joint Femur- thigh bone Tibia- shin bone Patella- knee cap Fibula

Joints of the Knee Patella Femoral Joint As the knee flexes, the patella slides up and down on the front of the femur. Joint cartilage protects these bone surfaces from friction. Tibiofemoral Joint Formed by the femur and the tibia. The joint where the “bending” of the knee occurs.

Meniscus Ring-like structures that fit between the tibia and the femur. Functions Cushing of the bones of the knee Provides stability to the knee

Hyaline Cartilage Joint Cartilage- covers the ends of bones and allows the bones to slide smoothly over one another.

Medial Collateral Ligament The MCL protects the knee from valgus stresses. MCL Gives stability to the medial (inside) aspect of the knee.

Lateral Collateral Ligament LCL Gives stability to the lateral (outside) aspect of the knee. The LCL protects the knee from varus stresses.

Posterior Cruciate Ligament PCL Located on the inside of the knee joint. Protects the tibia from moving backward (posteriorly) under the femur.

Anterior Cruciate Ligament ACL Keeps the tibia from sliding forward on the femur. Located between the femur and the tibia.

Quadriceps Muscle Group Made up of 4 muscles Rectus femoris Vastus lateralis Vastus medialis Vastus intermedius Performs the Knee Extension movement

Hamstring Muscle Group Made up of 3 Muscles Biceps femoris Semitendonosis Semimembranosus Performs the Knee Flexion movement

Hamstring Strain Also known as a “Pulled Hamstring” The muscle tissue is either completely or partially torn. Mechanism of injury: Hip flexion with knee straight. Forceful knee flexion H.S. Tear may occur at the origin of the muscle.

Quadriceps Strain Mechanism of injury: Forceful knee extension; usually during weight bearing Rapid, forceful knee flexion.

Medial Collateral Ligament Sprain / Tear Mechanism of injury- a valgus stress (bending the knee inward) to the knee. May occur from a blow to the outside of the knee. Different grades of tears range from a stretching of the ligament to a complete tear. Common sports injury.

Lateral Collateral Ligament Sprain / Tear Mechanism of Injury: Varus stress on the knee (knee bend from the inside outward). Not as common as MCL sprains/tears

Anterior Cruciate Ligament Tear Considered a severe injury for an athlete to receive. A complete tear will require surgery, and 9 months of rehab. Mechanisms of Injury Foot planted and lower leg rotates. Direct blow forces the knee into hyperextension. Direct blow to the back of the tibia, moving the tibia anteriorly.

Posterior Cruciate Ligament Tear Mechanisms of Injury: Knee is forcefully hyperflexed- falling on bent knee with body weight. Blow to the anterior part of the tibia with knee bent, forcing the tibia backwards. “Dashboard Injury”

Patellar Tendonitis “Jumper’s Knee” Overuse injury, inflammation of the patellar tendon from repetitive stesses. The athlete will experience: Quadriceps weakness Tenderness over the patellar tendon.

Patella-Femoral Pain Syndrome Also known as “Chondromalacia Patella” Pain is described underneath or behind the knee cap. Pain with running, jumping and other repetitive knee movements. Causes include: Malalignment of the patella in the femoral groove. Falling on kneecap.

Meniscus Tear Mechanisms include: Twisting Cutting Decelerating A “popping” sound my occur. Symptoms include: Stiffness and swelling Tenderness in the joint line Collection of fluid ("water on the knee") Catching or locking of your knee Knee buckling

Tibiofemoral Dislocation Femur and Tibia bone are forced out of place. Considered a medical emergency due to the potential for entrapment of blood vessels and nerves between the disjointed bones.