STRUCTURE OF THE KNEE

 

 

    Three articulating bones in the lower extremity of the body are involved with the knee, the patella, tibia and the femur. The fibula also helps with knee joint stability, but has no involvement with the joint capsule.

 

    The knee is a hinge joint and consists of two synovial joints, the tibiofemoral and the patellofemoral joints, and small bony structures that are involved with origin and insertion points of muscles and ligaments.  These joints are mainly composed of type I collagen soft tissue which helps control biomechanical loads transmitted throughout the joint.

 

 

 

 

ANATOMY OF THE KNEE

 

Bones and Ligaments

 

 

 

 

 

 

 

LIGAMENTS OF THE KNEE

 

Ligament

Origin

Insertion

Function
Medial Collateral Ligament (MCL) Medial Epicondyle of Femur Superior Tibia The MCL protects the medial side from a valgus force.
Lateral Collateral Ligament (LCL) Lateral Epicondyle of Femur Head of Fibula The LCL protects the lateral side from a varus force

Anterior Cruciate Ligament (ACL)

 Lateral Condyle of Femur Tibia Plateau (anterior intercondylar area)

The  ACL prevents anterior displacement of the tibia relative to the femur.
Posterior Cruciate Ligament (PCL) Medial Condyle of Femur Tibia Plateau (posterior intercondylar area) The PCL prevents posterior displacment of the tibia relative to the femur.
Arcuate Ligament Lateral Epicondyle & Condyle of Femur Medial Fibular head  Strengthens the joint capsule posteriorlaterally.
Oblique Popliteal Ligament Medial Tibial Condyle Lateral Femoral Condlye  A recurrent expansion of the tendon of the semimembranosus that reinforces the joint capsule posteriorly.
Patellar Ligament Apex of the Patella Tibial Tuberosity A very strong, thick fibrous band that helps maintain alignment of the patella and the way it articulates on the surface of the femur.

 

 

 

 

 

THE MENISCI OF THE KNEE

 

The knee is composed of two fibrocartilaginous menisci, the medial and lateral meniscus. The menisci are considered anatomic incongruences between the articular surfaces of the tibia and femur.  The menisci serve four very important functions:

 

  • Disperses load over a larger percentage of surface area

  • Absorb shock

  • Increase the stability of the joint

  • Decrease friction for the articulating surfaces

     

(Starkey & Ryan 2002)  

 

 

 

 

 

 KNEE MOVEMENT LIMITATIONS

 

 

     The knee has limitations with the movements it can produce.  It is capable of internal and external rotation, flexion and extension.  The anatomical structures that cause the knee to only move within those parameters are the ligaments and menisci.  These structures help the knee stay within its capable range of motion (ROM).

 

     The ROM in the knee for internal rotation and external rotation is limited when compared to flexion and extension.  In internal rotation the average person is capable of producing 10° and 30° for external rotation.  When the hip is extended the knee is capable of 120°, if the hip is flexed is can produce 140°, and when the knee is passively flexed it produces 160°.  (Clinically Oriented Anatomy)

 

 

 

 

REFERENCES

 

Starkey C, Ryan J.  Evaluation of Orthopedic and Athletic Injuries 2nd Edition. F.A. Davis Company 2002.

 

Moore, K.L, DalleyA.F. Clinically Oriented Anatomy 5th Edition. Lippincott Williams & Wilkins May 2005.

 

 

 

 

 

  THE KNEE IS NOT THE DEVIL!!!!


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