Anatomy of the Knee Not a true hinge joint

The knee is NOT a true hinge joint! Non-weight bearing Full extension the tibia rotates laterally In flexion the tibia rotates medially Weight bearing the femur rotates medially on tibia

Lateral Collateral Ligament (LCL) Connects the lateral condyle of femur to the fibular head Shaped like a pencil-1”-1.5” long Function: prevents adduction of the tibia

Medial Collateral Ligament(MCL) Connects medial condyle of femur to the abductor tubercle of tibia Flat, long, thick ligament - 6”-6.5”long Attaches to medial meniscus Prevents abduction of tibia

Anterior Cruciate Ligament (ACL) Located anteriorly on tibia and twists as it attaches posteriorly on femur (medial-lateral)

Function of ACL Prevents anterior displacement of tibia Prevents hyperextension Prevents medial/lateral rotation of tibia Prevents posterior displacement of femur

Rotation of ACL Prevents medial/lateral rotation ACL is stretched and torn during rotation

Which knee? Notice medial insertion on tibia and lateral insertion of femur

Posterior Cruciate Ligament (PCL) Runs lateral from tibia to medial attachment of femur MAJOR STABILZER OF THE KNEE Hyperextension damages PCL; during lateral rotation PCL tightens

Posterior Cruciate Ligament (PCL) Function: 1. Prevents anterior displacement of femur 2. Prevents posterior displacement of tibia

Meniscus Medial – C shaped Lateral – O shaped Function: deepens the articulation of joint and adds stability Complaint – “giving out”

Bursae Sacs of Knee Fat pads around the knee that provide cushioning

Synovial capsule Encapsulated watertight membrane that secretes a fluid that lubricates and nourishes the joint When irritated a cyst forms at the weakest part of the capsule – back of the knee – popliteal space

Retinaculum Thick fascia that holds tendons in place around the knee

Patella and patellar tendon Patella - sesamoid bone that increases the torque Quadriceps tendon attaches rectus femoris to superior aspect of patella Patella tendon attaches the quadriceps to the tibial tuberosity

Quadriceps Rectus femoris – 2 joints Vastus lateralis Vastus intermedius Vastus medialis

Hamstrings Biceps femoris – lateral Semitendinosus – medial 2nd Semimembranosus – medial 1st

Gastrocnemius/Soleus Gastrocnemius is a two jointed muscle: Plantar flexion of the ankle and flexion of the knee.