Transcript Knee Unit Review

Knee Review
Major Points
Mr. Brewer
Knee Facts
•
•
•
•
The Knee is a “Hinge” joint.
4 Bones
4 Major Ligaments
Important structures:
– Menisci (2), Bursa Sacs and Synovial Sac.
– **Largest Synovial Sac in the body**
• Knee Range of Motion (ROM) is roughly 0-150 degrees.
– 0 = Full Extension
– ~150 = Full Flexion
– ** (-) degrees are used for someone’s knee who goes into
HYPERextension.**
Bones
Patella:
- AKA the Knee Cap
- The Largest Sesamoid bone in the body
- Encapsulated by the Quadricep Tendon
- Center piece of the Quadriceps and their distal
attachment to the tibial tuberosity.
Tibia
- AKA the “Shin bone”.
- Most weight bearing lower leg bone.
- Location of major landmarks such as:
- Tibial Plateau (place for menisci to sit and femur
to come down on)
- Tibial Tuberosity which is the distal insertion point
for the quadricep muscles.
Fibula
• Little significance at the knee joint.
• Is part of the knee joint at it’s most proximal
aspect.
• The distal insertion point for the LCL and
Biceps Femoris muscle.
• Proximal (Top) part of the Fibula is known as
the Head of the fibula.
Femur
• Longest Bone in the body.
• Condyles are smooth and made of mostly
articular cartiledge that allows minimal
friction when flexing and extending the knee
joint.
• Distal Landmarks include:
– Adductor Tubercle
– Lateral and Medial Epicondyles
– Lateral and Medial Condyles
Cruciate Ligaments
Cruciate = CROSS “X”
1. ACL – Anterior Cruciate Ligament
-
-
Attaches distally to the anterior aspect of the tibial
plateau.
Prevents the tibia from translating(moving) anteriorly.
Not as thick as the PCL
2. PCL – Posterior Cruciate Ligament
- Attaches distally to the posterior aspect of the tibial
plateau.
- Helps prevent the tibia from translating posterior AND
from allowing the knee to go beyond it’s normal range of
knee extension.
- PCL is often damaged from Knee Hyperextension.
Collateral Ligaments
Collateral Ligaments
1. MCL – Medial Collateral Ligament
- Thick ligament that connects the Femur and the Tibia medially to
provide stability for the medial aspect of the knee.
- Thicker and stronger of the 2 collateral ligaments.
- Deep fibers have attachments to the Medial Meniscus.
- Valgus force (pressure from lateral knee attempting to “gap” the
medial joint line) tests the strength and stability of the MCL
1. LCL – Lateral Collateral Ligament
- Ligament that provides stability to the lateral aspect of the knee.
- Connects Femur to the Fibula
- Smaller and less stable than MCL.
- Varus force (pressure from medial knee attempting to “gap” the
lateral joint line) tests the strength and stability of LCL
Other Structures
• Menisci:
– MAJOR Role of the Menisici: “SHOCK ABSORBER”
– Also reduces friction (rubbing) of bone-on-bone, specifically the femur
and tibia.
– Medial Meniscus
• Shaped like a “C”.
• Larger than Lateral Meniscus
• Attaches to MCL
– Lateral Meniscus
• Semi-Circular in shape
• Smaller than Medial Meniscus.
**ZONES: (From Lateral to Medial OR Outside to Inside)**
1. Red-Red (Repairable)
2. Red-White (MAYBE repairable)
3. White-White (NOT repairable)
Bursa Sacs
• Small fluid-filled sacs located near insertion
points.
• Main role of a bursa sac is to reduce friction
between tendon and bones.
• Filled with “synovial” fluid, just like joints.
Muscles
Quadriceps:
(4) Four Muscles:
**All 4 muscles insert distally at the tibial tuberosity**
From Proximal to Distal:
Quadricep Muscles  Quadricep Tendon  Patella  Patellar Ligament 
Tibial Tuberosity
-
3 Vastus Muscles
- ONLY cross the knee joint
- Therefore are only responsible for Knee extension
-
1 Rectus Femoris Muscle
- Cross both KNEE and HIP joints
- Therefore is responsible for both Knee Extension and Hip Flexion.
Hamstrings
3 Major Muscles:
- 1 Lateral
- Biceps Femoris
- 2 Medial
- Semitendinosus (More tendonous)
- The “T” in SGT, the acronym for the 3 muscles that
insert at the Pes Anserine on the anterior, medial
aspect of the tibia.
- Semimembranosus (More muscle/membranous)
Gracilis
• One of the major HIP ADDUCTOR muscles
that crosses the knee joint as well as the hip
joint.
• The “G” in SGT for muscles that insert to the
Pes Anserine.
• Responsible mainly for HIP Adduction, and
supports the MCL because of the fact that it
crosses the knee joint on the medial aspect of
the leg.
Sartorius
• Longest Muscle in the body.
• The “S” in SGT for the muscles that insert to
the Pes Anserine.
• Is responsible for a combination of
movements, but mostly:
– Hip Flexion WITH Hip EXTERNAL rotation.
(Figure 4)
• Has a proximal attachment to the ASIS of the HIP.*
SGT and the Pes Anserine
Pes Anserine = Latin for “Goose foot”
- Location for the insertion of the SGT
- Sartorius
- Gracilis
- SemiTendinosus
- Pes Anserine Bursa lies underneath to reduce
friction of those 3 muscle tendons and the
tibia.
Popliteus
Small muscle in the back of the knee.
- Major action created is Knee Flexion.
- Plays a large role in “unlocking” the knee from
full extension to initiate Knee Flexion.