The Knee

Anatomy of the Knee

Anatomy of the Knee on YouTube:

https://www.youtube.com/watch?v=_q-Jxj5sT0g

Play from RealPlayer (open)

Video is also saved on desktop if it isn’t playing properly!

Labelling Structures of the Knee

Key Structures

Bones: femur, tibia, patella Muscles: quadriceps (anterior),

gastrocnemius and hamstrings (posterior) Ligaments:

◦ Anterior Cruciate Ligament: stops anterior mov’t of tibia relative to the femur

◦ Posterior Cruciate Ligament: prevents posterior mov’t of the tibia relative to the femur

◦ Medial Collateral Ligament: reinforces the joint capsule medially

◦ Lateral Collateral Ligament: reinforces the joint capsule laterally

Key Structures

Menisci: The end of the femur is

covered with articulating cartilage which rests at the end of the tibia

There lie two thick fibrocartilage articular discs called the menisci (meniscus-singular): the lateral meniscus & medial meniscus

They sit on the tibial condyles and help increase the stability of the knee joint

What is the Knee Joint?

The knee joint is made up of the articulation of the femur and the tibia. The femur however does not come in contact with the fibula, but the fibula interacts with the tibia.

Type of Joint

The knee joint was first thought to be a hinge joint because it was believed to be responsible for only flexion and extension

However, the knee can rotate the leg medially and laterally to a small degree

Therefore, the knee is considered to be a modified ellipsoid joint which is a type of synovial joint

KNEE INJURIES

Because of the poor stability in the knee, as well as all the structures involved in the knee joint, discomfort and injuries are unfortunately, quite common! Ligament Tears: ◦ ACL – look at Q angle ◦ PCL ◦ Unhappy Triad

Patellofemoral Syndrome Patellar Tendinitis Osgood Schlatter Bursitis

Injuries: Ligament Tears

ACL tear

What motion of the tibia could be responsible for this injury? ◦ Anterior movement (forward movement) of the tibia relative to the femur

More common in sports where foot is planted and athlete must rapidly change directions (e.g. Soccer, football, Ultimate)

The Q-Angle

Q-angle stands for the quadriceps angle

The Q angle is formed by two lines drawn: 1. From the Anterior Superior Illiac Spine

(ASIS) through the centre of the patella

2. From the tibial tuberosity through the centre of the patella

Research indicates that a Q-angle greater than 20 increases the risk of knee injuries

Measuring Your Q-Angle

Find a friend

Locate their ASIS, tibial tuberosity and the centre of their patella

Create two lines to form your Q-angle – use string or rulers to visualize this!

Q-Angle Results

Question: Who are more prone to knee injuries, based on

their Q-angle - men or women?

Answer: Generally, because a woman’s pelvis is wider,

her Q-angle will be larger than a man’s. This predisposes her to knee ligament tears, among other knee injuries.

An NCAA study showed that women suffered ACL injuries four times more often in basketball; three times more often in gymnastics; and two-and-a-half times more often in soccer.

Posterior Cruciate Sprain

PCL tears can occur when a football or soccer player falls on a bent knee.

Motor vehicle accidents are another common cause of injury to the PCL. When the driver or passenger strikes the bent knee just below the kneecap (patella) against the dashboard, the force can tear the PCL and damage other ligaments, bones and muscles.

PCL Injury

Signs and symptoms Marked, immediate swelling (within three hours of the injury) Difficulty walking after the injury Painful to move the knee Occasionally, a feeling of instability, or the knee "giving way“

The Unhappy Triad

When the knee suffers a blow to the lateral side, the medial side of the knee is affected: the medial meniscus is torn, the MCL is torn and the ACL is torn.

These three traumas were coined: the Unhappy Triad

This injury is commonplace in football, rugby and soccer where lateral blows to the knee are possible

Medial

Patellofemoral Syndrome

Gradual onset of anterior knee pain or pain around the patella

More common in adolescents, young adults and females are more prone than males

Often aggravated by sports such as running, volleyball and basketball

There is quite a bit of disagreement in the sport medicine community as to its cause

Factors Contributing to PFS

Overuse/Overload: ◦ repeated weight bearing impact, landing from jumps

Biomechanical Instability: ◦ flat feet (pronation) causes internal rotation of tibia and femur which stresses the PF joint

◦ high arches puts undue stress on PF joint ◦ Q-angle?

Muscles ◦ Muscle weakness or imbalance (especially quads: hammies)

Patellar Tendonitis

What is patellar tendonitis? Patellar tendonitis, also called jumper's knee, is

inflammation in the band of tissue (the patellar tendon) that connects the patella to the tibia.

How does it occur? The most common activity causing patellar

tendonitis is too much jumping. Other repeated activities such as running, walking, or bicycling may lead to patellar tendonitis. All of these activities put repeated stress on the patellar tendon, causing it to be inflamed.

“Jumper’s Knee”

Osgood-Schlatter disease

Osgood-Schlatter (OS) disease is one of the most common causes of knee pain in the adolescent.

During periods of rapid growth, stress from contraction of the quadriceps is transmitted through the patellar tendon onto a small portion of the partially developed tibial tuberosity.

The repeated stress can cause the tendon to pull away from the tibia, causing pain and swelling.

Osgood-Schlatter disease

Bursitis

“Carpet Layer’s” knee.

This is caused by direct trauma.

Tomorrow/Thursday/Friday

Thanks for your patience and attention today!

Tomorrow, and the rest of the week, please bring materials to create a model of a joint. See page in workbook for material suggestions: Tennis balls

Rubber bands/exercise bands

Balloons

Rods or dowels

Toilet paper rolls

Modelling clay