Anatomy: Knee Flashcards
1
Q
Frontal Plane Analysis: Normal Alignment
A
- Alignment described in “varus” or “valgus”
- Measurements using Anatomical or Mechanical axis
- Anatomical Axis
- Femur: oblique
- TIbia: Vertical
- Valgus (~ 5 degrees)
- Varus: knees out: joint opens laterally; compresses forces on medial side
- Valgus: knees in: joint opens medially; compresses forces on lateral side.
2
Q
Abnormal LE Alignment: Frontal Plane: Genu Valgum
A
- Defined as medial TF angle > 195 degrees
- Consequences:
- Increased compressive forces lateral condyles
- Increased tensile forces medial structures
3
Q
Abnormal LE Alignment: Frontal Plane: Genu Varum
A
- Defined as medial TF angle <180 degrees
- Consequences:
- Increased compressive forces on medial condyles
- Increased tensile forces on lateral structures
4
Q
Sagittal Plane Analysis: Normal Anatomical Position
A
- LOG passes slightly anterior to knee joint
- Normal TF angle= 180 degrees
- Little to no muscle activity required in static posture
- Support provided by posterior structures.
5
Q
Abnormal LE Alignment: Sagittal Plane: Genu Recurvatum
A
- LOG falls substantially anterior to knee joint
- Posterior joint capsule and related structures under considerable stress
- May result in adaptive lengthening
- Increased compressive forces anterior aspect of femoral condyles and tibial plateaus
6
Q
Proximal TIbia: Osteology
A
- Medial condyle
- Lateral Condyle
- Intercondylar eminence: ACL, PCL, and menisci attach here
- TIbial plateau
- Tibial Tuberosity
- Tibial Crest: bony prominence down the anterior femur
7
Q
Proximal Fibula: Osteology
A
Fibular Head: biceps femoris, lateral collateral ligament
Neck of the Fibula: Common peroneal n.
8
Q
Distal Femur: Anterior View
A
- Medial Condyle
- medial epicondyle
- Lateral Condyle
- lateral epicondyle
- Adductor tubercle: where you the adductor Magnus attaches
9
Q
Femoral Condyles: Tibiofemoral Articular Surfaces
A
- Medial condyle is larger and projects farther distally
- Covered w/ articular cartilage
- Intercondylar (trochlear) groove: where the patella lies
- Intercondylar fossa: where the cruciate ligaments go through
10
Q
Distal Femur: Posterior View
A
- Linea Aspera
- Supracondylar Lines
11
Q
TIbiofemoral Joint Classification
A
- Diarthrodial (synovial)
- Bicondylar
- Biaxial
- Compound: multiple articulations meaning that there is a medial and lateral surface
- Complex: disc Fibrocartilage
- Functions primarily as a hinge joint (flexion and extension)
- Some rotation in the transverse plane
- Closed packed position is also called the screw-home position
12
Q
Members of Knee Joint
A
- Femoral condyles
- Intervening menisci
- Tibial plateaus and condyles
13
Q
Tibial Condyles: Proximal Tibia
A
- Medial Tibial condyle or plateau
- Is longer in the anteroposterior direction
- The oval-shaped medial tibial plateau is larger (~50%)
- Lateral tibial condyle or plateau
- Is shorter (smaller) in the anteroposterior direction
- More circular in shape
- The articular cartilage is thicker than that of the medial tibial plateau
14
Q
Tibiofemoral Osteokinematics
A
- Normal knee flexion= 140 degrees
- Normal knee extension= 0 degrees
- Impact of 2 joint muscles:
- with hip extended, knee flexion ROM may be limited to 120 degrees
- with hip flexed, knee flexion ROM may be increased to 150-160 degrees
15
Q
Tibiofemoral Osteokinematics: Functional ROM (Sagittal Plane)
A
- Gait requires 60 degrees knee flexion
- Stair climbing requires 80 degrees knee flexion
- Sitting in a chair requires at least 90 degrees knee flexion
16
Q
Tibiofemoral Arthrokinematics
A
- Tibial articular surfaces are concave
- Femoral articular surfaces are convex
- Open chain: concave on convex
- Tibia on femur; anterior roll and anterior glide
- Closed chain: Convex on concave
- Femur on Tibia; posterior roll and anterior glide
- 0-25 degrees of CC flexion causes posterior roll of femur on a fixed tibia
- After 25 degrees posterior roll is accompanied by an anterior glide of femur
17
Q
Locking Mechanism of the Knee (Screw-Home Mechanism) OKC
A
- Open Kinetic Chain (OKC) in a non-weight bearing position
- 30 degrees from full extension
- Lateral tibial condyle completes arthrokinematics first
- As extension continues the medial tibial condyle arthrokinematics continues
- Results in external rotation of the tibia
- Brings joint into CPP
18
Q
Locking Mechanism of the Knee (Screw-Home Mechanism) CKC
A
- Closed Kinetic Chain (CKC) in a weight-bearing position
- 30 degrees from full extension
- LFC completes arthrokinematics first because it is smaller than the MFC
- As extension continues the MFC arthrokinematics continues
- This results in internal rotation of the femur
- Brings joint into the CPP (majority of the supporting ligaments to become taut)
- Coming out of CC the femur will externally rotate as the knee flexes
19
Q
Unlocking the Knee: TIbiofemoral Arthrokinematics
A
Open Chain
- First 30 degrees of flexion
- Medial tibial condyle moves first
- Followed by lateral condyle which causes IR of tibia
- Brings knee into OPP
Closed Chain
- First 30 degrees of flexion - Medial femoral condyle moves first - Followed by lateral condyle which causes ER of femur - Brings knee into OPP
20
Q
Capsular Kinesiology: Tibiofemoral Joint
A
- Closed Packed Position: full knee ext with full ER
- Open Packed Position: 20-30 degrees of knee flexion
- Capsular pattern: greater limitation in flexion than extension
21
Q
Patella
A
- Sesamoid bone (largest in body)
- Triangular with apex at inferior pole
- Posteriorly its surface should be smooth
- By holding the quadriceps further forward, adds a great deal to effectiveness of quadriceps pull
- proximal aspect: base
- Distal aspect: apex or inferior pole
22
Q
Patellofemoral Joint Classification
A
- Diarthrodial
- Planar
- Defined by the shape of the patellar surface of the femoral condyles
23
Q
Members of Patellofemoral Joint
A
- Posterior surface of patella and anterior surface of femoral condyles
- Least congruent joint of the body
