Kinesiology 360 - Section 7: The Lower Extremities (The Knee Joint)

Interior Ligaments

1. Anterior Cruciate Ligament: attaches proximally to the medial aspect of the lateral femoral condyle, and distally to the posterior aspect of the anterior intercondylar part of the tibial table. 2. Posterior Cruciate Ligament: attaches proximally to the anterior inferior lateral aspect of the medial femoral condyle, and distally to the posterior aspect of the posterior intercondylar area of the tibial table. Checks: rotation and hyperextension

The Distal Extremity

1. Fibular Notch: articulation point for the lateral malleolus of the fibula, located on the lateral border of the distal end.

Movements of the Tibiofemoral (Knee) Joint

1. Flexion 2. Extension 3. Hyperextension

Medial and Lateral Ligaments

1. Lateral Collateral Ligament: attaches superiorly to the lateral epicondyle of the femur and inferiorly to the head of the fibula. Checks: hyperextension, rotation, adduction 2. Medial Collateral Ligament: attaches superiorly to the medial epicondyle of the femur and inferiorly to the medial aspect of the tibia below the tibial condyle. Checks: hyperextension, rotation, adduction Note: a small amount of internal/external rotation of the knee is possible in a flexed-unsupported position as the medial and lateral collateral ligaments become slack.

The Superior Extremity (Head)

1. Medial and Lateral Condyles 2. Intercondyloid Eminence 3. Intercondyloid Tubercles 4. Anterior Intercondyloid Fossa 5. Posterior Intercondyloid Fossa 6. Tuberosity of the Tibia

Posterior Ligaments

1. Oblique Popliteal Ligament 2. Arcuate Popliteal Ligament

Ligaments of the Knee

1. Posterior Ligaments 2. Medial and Lateral Ligaments 3. Interior Ligaments

The shaft of the tibia has how many primary borders?

3 1. Anterior Border 2. Lateral Border (Interosseus Crest) 3. Medial Border

Assisting Muscles

A broad category of muscular actions used to describe such actions as neutralizers and stabilizers.

Tuberosity of the Tibia

An irregular surfaced prominence located inferior to the condyles on the anterior side of the tibia.

What is the skeletal depression anterior to the intercondyloid tubercles of the tibia?

Anterior Intercondyloid Fossa

Extension of the Knee Joint

Extension of the knee joint is characterized by an increase in the posterior angle of the knee. Extension may be accomplished in different ways, but primarily by: 1. An anterior-inferior movement of the tibia from anatomical position, such as seen when kicking a ball. 2. A superior-anterior movement of the femur away from the tibia, such as standing from a seated position. The prime muscles of extension of the knee joint are the quadriceps muscle group, located on the anterior aspect of the femur and knee joint.

Medial and Lateral Retinicula

Fibrous attachments running from the patella posteriorly to the distal end of the femur and attaching to the medial and lateral epicondyles, respectively.

Biokinematics of Knee Flexion/Extension

Flexion and extension of the knee requires the production of large rotational moments (torque), particularly during the eccentric flexion movement common in human weight-bearing activities. Fortunately, the anatomical structure of the knee assists in the generation of rotational moments. Particularly important is the contribution of the patellofemoral joint in increasing the moment arm of the common quadriceps tendon as it contracts to product knee extension. The moment arm of the quadriceps tendon to the center of rotation of the knee has been shown to vary through the range of motion. PAGE 11

Biokinematics of Knee Flexion/Extension

Flexion of the knee from an extended or "locked" position provides an excellent illustration of coupled motion - rotation an translation acting in unison. As flexion (rotation) of the knee joint occurs, the femur slides (translates) anteriorly on the proximal tibial surface. This is due primarily to the anterior cruciate ligament, which becomes taut and forces the convex-shaped femoral condyles to translate forward on the concave proximal tibial surface. The reason for translation during knee flexion is important to understand due to the clinical implications of improper translation. Consider knee flexion not couples with translation. The tibia moves posterior-superior during weight-bearing, and without translation is left with very little contact surface beneath the vertically-downward directed weight from the femur. This creates an extremely unstable knee in a supported position. PAGE 10

Flexion of the Knee Joint

Flexion of the knee joint is characterized by a decrease in the posterior angle of the knee. This may be accomplished in different ways, but primarily by: 1. A posterior-upward movement of the tibia from anatomical position, such as seen when standing on one food and bending at the knee. 2. A posterior-downward movement of the femur toward the tibia, such as in sitting down in a chair. The prime moving muscles of flexion of the knee joint are the hamstring group located on the posterior side of the knee.

Torsional Loading of the Ligaments of the Knee

Frontal View: Torsion of the tibia about the femur, such as would be experienced in a sudden change of direction with the support foot planted, would create a shear force on the collateral ligaments - multiplied by the shear forces moment arm to produce a destructive torque on the collateral ligaments. Sagittal View: The same torsion applied to the cruciate ligaments would primarily produce tensile force, stretching the ligaments along their longitudinal axis - producing far less destructive force - THE CRUCIATE LIGAMENTS ARE DESIGNED TO DISSIPATE TORSION.

The superior extremity of the tibia is more commonly known as the:

Head

What is the skeletal projection located between the condyles of the tibia?

Intercondyloid Eminence

What are the skeletal projections adjacent to the intercondyloid eminence of the tibia?

Intercondyloid Tubercles

Internal/External Rotation of the Knee

Internal and eternal rotation of the knee is possible under specific conditions. In a standing position, the knee "locks" with the skeletal articulations in contact, and the collateral ligaments in a taut position. However, when the knee is unsupported and flexed, the contact surface of the articulating regions are greatly reduced, and the collateral ligaments are slackened, allowing for some internal and external rotation. The prime moving muscles of internal/external rotation of the knee joint are the hamstring group due to their medial (semitendinosus, semimembranosus) and lateral (biceps femoris) lines of pull relative to the knee joint. In addition, the popliteus, with it's transverse plane line of pull around the knee joint is a prime mover for inward rotation of the knee joint.

The common name for the interosseus crest is the:

Lateral Border

Patellar Ligament

Ligament continuous inferiorly with the quadriceps tendon serving as the distal attachment for the quadriceps muscle group on the tibial tuberosity of the tibia.

What are the superior protrusions that articulate with the condyles of the femur to form the knee joint?

Medial and Lateral Condyles

Prime Movers

Muscles that exhibit a constant state of neurological excitation throughout the range of motion of a movement as recorded by Electromyography (EMG)

Extension

Plane of Motion: Sagittal Axis of Motion: Medial-Lateral Prime Movers: 1. Rectus Femoris 2. Vastus Lateralis 3. Vastus Intermedius 4. Vastus Medialis

Flexion

Plane of Motion: Sagittal Axis of Motion: Medial-Lateral Prime Movers: 1. Semitendinosus 2. Semimembranosus 3. Biceps Femoris

External (Outward) Rotation

Plane of Motion: Transverse Axis of Motion: Vertical Prime Movers: 1. Biceps Femoris

Internal (Inward) Rotation

Plane of Motion: Transverse Axis of Motion: Vertical Prime Movers: 1. Semitendinosus 2. Semimembranosus 3. Popliteus

What is the skeletal depression posterior to the intercondyloid tubercles of the tibia?

Posterior Intercondyloid Fossa

Anterior Intercondyloid Fossa

Skeletal depression posterior to the intercondyloid tubercles.

Posterior Intercondyloid Fossa

Skeletal depression posterior to the intercondyloid tubercles.

Intercondyloid Eminence

Skeletal projection located between the condyles.

Intercondyloid Tubercles

Skeletal projections adjacent to intercondyloid eminence.

Medial and Lateral Condyles

Superior protrusions that articulate with the condyles of the femur to form the knee joint.

Quadriceps Tendon

Tendon linking the distal end of the quadriceps muscle group to the patella, continuous with the patellar ligament.

Skeletal Anatomy of the Tibia

The Superior Extremity (Head) The Shaft The Distal Extremity

The Anterior Aspect of the Knee

The anterior side of the knee is dominated by the patellofemoral joint, formed primarily by the patella and patellar ligament.

Bursae

The bursae are filled with synovial fluid similar to the joint capsule itiself. Bursae located in the anterior aspect of the knee include: 1. The Gastrocnemius Bursae 2. The Suprapatellar Bursae 3. The Intrapatellar Bursae which all serve to minimize the friction of the patellofemoral joint as it tracks across the tibiofemoral joint.

The Fibula

The fibula is the lateral of the two bones of the leg (shank), but does not articulate at the knee or bear weight.

The Anterior and Posterior Cruciate Ligaments

The function of the anterior and posterior cruciate (crossing) ligaments are to protect against rotational motions of the tibia (torsion) about the femur. The design of the cruciate ligaments provides an opportunity to investigate the intelligent biomechanical design of these ligaments in carrying out their functions. This design is explained by contrasting the mechanical loads placed on the cruciate ligaments during knee torsion (rotation) with the loads imposed on the collateral ligaments by the same loading. p.7

Sagittal Plane Movements of the Tibiofemoral (Knee) Joint

The movements of the knee joint will be discussed together with the muscles that produce these actions. Muscular actions are divided into: 1. Prime Movers 2. Assisting Muscles Only prime moving muscles will be addressed in the analysis of movements at the knee joint.

Fibrous Attachments of the Patellofemoral Joint

The patella is held in place by four primary attachments. 1. Quadriceps Tendon 2. Patellar Ligament 3. Medial and Lateral Retinicula

The Patellofemoral Joint

The patellofemoral joint is a gliding joint that slides up and down on the posterior surface of the patella and condyles of the femur. The patella slides ("tracks") a total distance of approximately 8 cm in an adult superior-inferiorly. Classification: Gliding (Arthrodial)

The Posterior (Popliteal), Medial, and Lateral Aspects of the Knee

The posterior side of the knee (the popliteal region) is composed primarily of a series of ligaments supporting the knee. In addition, the popliteal bursae, and semimembranosus bursae are located in this region. The medial and lateral sides of the knee are composed primarily of ligamentous support.

The Tibia

The tibia is the largest bone within the leg (AKA shank), and bears the weight transfer of the body from the femur to the talocrural (ankle) joint.

The Tibiofemoral and Patellofemoral Joints

The tibiofemoral (knee) and patellofemoral articulations are both arthrodial, and thus are encased in a common joint capsule. Within the capsule, these joints utilize a series of bursae designed to cushion muscle and tendon contact with skeletal formations.

The Shaft

Three Borders: 1. Anterior Border: pointed border commonly known as the "crest". 2. Lateral Border (Interosseus Crest): points toward the interosseus crest of the fibula-bound by the interosseus membrane. 3. Medial Border: a continuation from the inferiorly-located medial malleolus. Three Surfaces 1. Medial Surfaces: have a convex direction and the most common area for exterior injury (a.k.a., shin). 2. Posterior Surface: popliteal line, an obliquely-running line located superiorly and posteriorly extending from the lateral to medial borders. 3. Lateral surface: intrinsic to the muscles of the leg.

The Knee Joint

Tibiofemoral Joint The tibiofemoral joint is formed by the articulation of the distal end of the femur and the proximal end of the tibia. The knee joint is the largest surface area articulation and one of the most complex joints of the human body. The skeletal formation of the knee includes the femur, tibia, and patella. Classification: Ginglymus (hinge) Joint

What is the irregular surfaced prominence located inferior to the condyles on the anterior side of the tibia?

Tuberosity of the Tibia