Patella Alta - An increase in the distance between the patella and the tibia

Patella Baja - A decrease in the distance between the patella and the tibia

The patella glides distally on the femur with flexion and proximally on the femur with extension

With full extension the patella has little or no contact with the femur

With flexion the patella sildes into the intercondylar groove

-Mobility of the patella is greatly reduced

-Patella moves closer to the axis for the knee

-Surface area contact is increased

Origin: distal half of the intertrochanteric line and medial lip of linea aspera

Insertion: upper border of patella by quadriceps tendon

Origin: Anterior, upper femur, lateral lip of upper 1/2 of linea aspera and the gluteal tuberosity

Insertion: upper border of patella by quadriceps tendon

Origin: ischial tuberosity and (long head) lower 1/2 linea aspera (short head)

Insertion: head of fibula and lateral condyle of tibia

Origin: ischial tuberosity

Insertion: superior, posterior medial surface of medial condyle of tibia

Origin: ischial tuberosity

Insertion: superior, anterior medial surface of the tibia

Origin: posterior surface of the lateral epicondyle of the femur

Insertion: upper posterior medial surface of the tibia

Biceps femoris, semimembranosus, semitendinosus

Assistance from sartorius, gracillis

Gastrocnemius helps in unloaded conditions

Knee is unlocked (flexion is started) by popliteus)

Otherwise known as the "Unhappy Triad" or "Terrible Triad"

Rupture of the ACL, MCL, and Medial Meniscus

-Lateral meniscus is also common with athletic injuries

Patella does not track correctly between condyles during flexion

May cause complete dislocation

Folds of synovial membrane become impinged by the patella or femoral condyles

Can become calcified or fibrotic

In full extension, the knee is in a "locked" position

-Medial condylel of femur is longer than lateral condyle of femur

-Tibial will externally rotate during the last portion of extension

-This produces a locking of the joint referred to as the screw-home mechanism

In order to unlock the knee the tibia must be rotated interally

Origin: Upper 2/3 or the anterior and lateral surface of femur

Insertion: Upper border of patella by quadriceps tendon

Origin: anterior inferior illiac spine & upper lip of acetabulum

Insertion: Upper border of the patella

Sagitall plane

-Flexion/Extension

Frontal Plane

-Minimal Abduction/Adduction

Transverse Plane

-Minimal Internal/External Rotation

(Frontal and transverse plane movement can occur when the knee is flexed and unloaded)

Frontal plane

1. Knee Valgus - The angle between proximal and distal segments opens laterally (knock-knee)

2. Knee Varus - The angle between proximal and distal segments opens medially (bowlegged)

Sagittal plane

1. Genu recurvatum - Hyperextension of the knee past 180

Transverse plane

1. Degree of version - Rotation of the knee past 0

Alignment of the knee is affected by the alignment of the hip, ankle, and foot

Misalignment can occur from

1. Misalignment of the hip, ankle, and foot bones

2. Muscle Imbalances

3. Abnormal Loads

May lead to deformities and injury

Attaches to tibia posterior surface of the tibia, posterior of the intercondylar ridge

Attaches to femur, Attaches to the posterior asepct of the lateral surface of the medial femoral condyle

Upward and forward from the posterior

Provides restraint for posterior movement of the tibia relative to the femur

Anterior Cruciate Ligament (ACL)

Attaches to tibia: anteriorly and just lateral to the intercondylar eminance

Attaches to femur posteriorly on the medial surface of the lateral epicondyle

Upward and backward alignment from anterior

Provides restrain for anterior movement of the tibia relative to the femur

There are 2 cruciate ligaments

Both cruciates limit rotation

Regulate the sliding of the femoral condyles over the tibia

Short and cordlike

Extends from the lateral epicondyle to the head of the fibula

Has two parts, Both originate from medial epicondyle of the femur

Anterior Segment

1. Longer of the two

2. Extends Distally

3. Attaches to the medial surface of the tibia

Posterior Segment

1. Shorter of the two

2. Extends distally and posteriorly

3. Attaches at the tibial condyle

There are 2 collateral ligaments

1. Medial collateral ligament (MCL)

2. Lateral collateral ligament (LCL)

They are primarily responsible for medial and lateral stability

Two fibrocartilage discs rest on the medial and lateral tibial plateaus

1. Cover 50% of the plateaus

2. Circular in shape

3. Wider towards the edges

Increase contact area between femur and tibia

1. Improve fit

2. Accommodate compressive forces

The knee joint capsule is the largest synovial joint capsule in the human body

Two layers (fibrocartilage & synovial) are seperate and do not cover same areas

The larger synovial layer is characterized by infoldings (plicae)

Articulation between the tibia and the fibula

1. Proximal

1a. Posterior, lateral, and inferior aspect of the lateral tibial epicondyle

2. Distal

2a. Head of the fibula

Small amount of movement in all three planes

Dissipates torsional stresses at foot and bending at the tibia

A triangular shaped sesmoid bone

Posterior surface is oval

A central ridge runs from poximal to distal

1. Creates medial and lateral facets

2. A third facet (odd facet) exists on the medial portion of the medial facet

Expanded proximal end

Consists of two large condyles (medial and lateral)

Separated by a large ridge (intercondylar eminence)

1. This forms two tibial plateaus

2. Also forms two articular facets (medial and lateral)

Anterior surface also contains the tibial tuberosity

Distal portion of the femur

1. Consists of two large condyles (medial & lateral)

2. Seperated by a large notch (intercondylar fossa)

3. The medial condyle is longer than the lateral condyle

3a. Both condyles align horizontally with each other

3b. Therefore, the shaft of the femur is slightly off from a vertical line

The knee is composed of the distal femur, the proximal tibia and the patella

Formed by three joints

1. Tibiofemoral joint

1a. A modified hinge joint or a double condyloid joint

2. Patellofemoral joint

2a. A gliding joint

3. Tibiofibular joint

3a. A gliding joint