Topic 4

Question 1

identify, classify and state the functions of the patella

Answer 1

Sesamoid bone
Base, apex, articular facets
Centred in intercondylar
groove of femur
Mechanical advantage for
knee extension

Question 2

describe the joint capsule of the knee

Answer 2

No complete capsule
Deficient anteriorly on femur
where quadriceps tendon is
Deficient anteriorly on tibia
where patella ligament attaches
to tibial tuberosity
Deficient posteriorly where
tendon of popliteus emerges
(posterior to lateral tibial condyle)
Receives much additional
ligamentous reinforcement

Question 3

describe the synovial membrane in the knee joint

Answer 3

Lines the joint capsule
Extensive and complex
Anteriorly attaches to patella
Posteriorly closes off
intercondylar fossa
Does not enclose the ACL or
PCL
Communicates with some
bursa

Question 4

what is knee retinacula

Answer 4

Medial & lateral patellar retinaculum
Aponeurosis – flat tendon
From vastus medialis & vastus lateralis
Medial retinaculum blends with
periosteum of tibia
Medial patellofemoral ligament
Adductor tubercle to vastus medialis
onto superomedial patella
Lateral retinaculum blends with iliotibial
tract
Some cross-over of fibres to over side

coming off the vastus lateralis and vastus medialis are the lateral and medial patella retinaculum - which are broad sheets connective tissue that sweep over the gap of the joint capsule. they compensate for the gap in the joint capsule.

the medial retinaculum blends with the periosteum of the tibia. We have an extra ligament called the patelloligament which prevents a lateral displacement of the patella.

lateral retinaculum blends with the iliotibial tract.

Question 5

list the bursae in the knee joint

Answer 5

Pes anserine
Suprapatellar
Extends 6cm superior to patella!
Infrapatellar
prepatella

Question 6

describe the fibular/lateral collateral

Answer 6

Fibular/Lateral collateral
ligament - extracapsular

Attaches:
Lateral femoral epicondyle
Lateral surface head of fibula

Limits:
Extension
Lateral rotation
Adduction or VARUS forces

Question 7

describe the popliteofibular ligament

Answer 7

Popliteofibular ligament - extracapsular

Attaches:
Popliteus tendon
Apex of head of fibula

Limits:
Lateral rotation of the tibia

Question 8

describe the patella ligament

Answer 8

Patella ligament - capsular

From patella to tibial tuberosity
Continuation of quadriceps
tendon
Receives the patellar retinacula

Function:
Mechanical advantage in knee
extension

Question 9

describe the tibial medial collateral ligament

Answer 9

Tibial/Medial collateral ligament - capsular

Attaches:
Medial femoral epicondyle
Medial tibial condyle
Medial tibial shaft
Medial meniscus

Limits:
Extension
Medial rotation
Abduction or VALGUS forces

Question 10

describe the oblique popliteal ligament

Answer 10

Oblique Popliteal - capsular 
Strengthens central posterior
joint capsule
Is an expansion of the tendon
of semimembranosus
Travels superolaterally to
femur

Question 11

describe the arcuate popliteal ligament

Answer 11

Arcuate Popliteal - capsular 
Strengthens inferolateral
posterior joint capsule
Is an expansion of the
tendon of biceps femoris
attachment
Travels superomedially
over popliteus

Question 12

describe the anterolateral ligament

Answer 12

Anterolateral ligament - capsular 
Attaches
lateral femoral condyle
midway between
anterolateral tubercle
(Gerdy’s tubercle) & head
of fibula
Some sources consider it
part of the ITB
stabiliser for rotation of the
tibia?

Question 13

describe the ACL

Answer 13

ACL - intracapsular 
Attaches
anterior intercondylar area of
tibia
posteromedial surface of lateral
femoral condyle
Extra-synovial
Limits
medial rotation
anterior slide of tibia on femur
3 anteriors on this slide

Question 14

describe the PCL

Answer 14

PCL - capsular 
Attaches
posterior intercondylar area of
tibia
lateral surface of medial femoral
condyle
attaches to lateral meniscus
Extra-synovial
Limits
medial rotation
posterior slide of tibia on femur
3 posteriors on this slide

Question 15

describe the posterior meniscofemoral ligament

Answer 15

Posterior meniscofemoral - capsular 
Connects lateral meniscus to
PCL
Secondary restraint to support
PCL
More in functional knee lecture

Question 16

describe the lateral and medial meniscus

Answer 16

Crescent shaped wedges of
fibrocartilage, thicker at ‘edges’

Shock absorption
Increase congruence
Medial meniscus - Larger, C-shaped, less
mobile as more attachments
Lateral meniscus - Smaller, almost circular

Question 17

describe the tibiofemoral joint

Answer 17

Tibiofemoral
Synovial
Condyloid (modified hinge)
Biaxial

Movements:
Flexion 140º
Extension 0º (hyperextension)
Internal/medial rotation 10º-20º if flexed
External/lateral rotation 30º-40º if flexed

Question 18

describe the patellofemoral joint

Answer 18

Patellofemoral
Patella surface of femur
Articular surface of patella
(facets)
Synovial
Plane

Question 19

when is the knee in close packed position

Answer 19

full extension

Question 20

factors contributing to stability at the hip

Answer 20

1. articular fit - reasonable congruency
2. acetabulum labrum - deepens socket and increases congruency
3. strong capsule - reinforced by ligaments
4. angle of inclination - increases contact area
5. muscles being parallel to neck of femur.

Question 21

what are factors contributing to mobility at the hip joint

Answer 21

1. acetabulum labrum - provides increased surface area for femoral head.
2. ball and socket joint - multiaxial

Question 22

how does the knee unlock?

Answer 22

Popliteus “unlocks”
knee by medially
rotating tibia.

Question 23

what is the functional significance the locking mechanism of the knee joint?

Answer 23

1. Important contributor to
tibiofemoral joint stability in
extension
2. “Close packed position”
• No muscle effort required to maintain
full knee extension
• Stable joint position: Maximum
contact between joint surfaces, tibial
tubercles lodged in the intercondylar
notch, ligaments tense
• BUT also uncomfortable, not the
preferred resting position of the joint

Question 24

what are the factors contributing to stability at the knee?

Answer 24

1. STATIC: combination of non contractile and
   bony elements
   e.g. menisci, ligaments, capsule, articular cartilage,
   ITB
2. DYNAMIC: muscles acting on or across the
   knee joint
   e.g. quadriceps, hamstrings, sartorius, TFL, gracilis,
   gastrocnemius, popliteus, ITB

Question 25

describe the menisci as a factor contributing to the stability

Answer 25

Static: Menisci • Due to their complex anatomy, the menisci serve a variety of biomechanical functions such as: 1. withstand load bearing forces 2. increase contact area at the tibiofemoral joint  reduces stress at the joint surfaces 3. assist in movement of femoral condyles 4. assist in stabilising translatory movements • Menisci occupy ~ 60% of contact area between femoral condyles and tibial plateau • Menisci transmit >50% total axial load applied to tibiofemoral joint.

Question 26

what are the attachments of the medial and lateral menisci

Answer 26

``` attachments of medial meniscus: • medial collateral lig • anterior and posterior cruciate ligs • semimembranosus ``` ``` attachments of lateral meniscus: • posterior cruciate lig • medial femoral condyle via meniscofemoral ligs • popliteus ``` medial meniscus has greater ligamentous and capsular restraint  limited motion, contributor to greater incidence of injury?

Question 27

what are the movements of the menisci

Answer 27

Movements of the menisci: * considerable distortion throughout range * both move posteriorly during flexion (lateral > medial) * keeps the menisci under the femoral condyles * both active and passive elements contribute to movt.

Question 28

describe the ligaments as a factor contributing to stability at the knee joint

Answer 28

Static: Ligaments • combinations of structures provide stability at the knee – no single structure in isolation • concept of primary and secondary restraints work together to provide stability primary restraints – ‘workers’ secondary restraints – ‘helpers’ • if primary restraint is damaged, the secondary restraint takes the load  deterioration and increased joint instability

Question 29

describe the iliotibial band as a factor contributing to stability

Answer 29

Dynamic: Iliotibial band (ITB) • part of the more extensive fascia lata • from the fascia surrounding tensor fascia lata and gluteus maximus and medius • extends to the anterolateral tibia • crosses both hip and knee • has fibrous connections to biceps femoris, vastus lateralis and the lateral patellar retinaculum – may influence patella tracking through these connections ``` • consistently taut regardless of hip or knee position • falls in front of the axis of the knee in extension, slips behind the axis in flexion (and is more prominent in knee flexion) • affords some lateral joint stability particularly in flexion • assists ACL in preventing anterior slide of tibia on femur ```

Question 30

describe the quadrate femoris as a factor contributing the stability of the knee joint

Answer 30

``` major extensor of knee • all parts of quadriceps femoris work throughout the range of knee extension  stabilises the patella within trochlear groove • greatest force needs to be developed at the end of extension range – final 15degs greatest mechanical disadvantage ```

Question 31

what are the functions of the vastus medialis oblique and longitudinal

Answer 31

Vastus medialis - longitudinal fibres (strongly bound to VI proximally): • knee extensor Vastus medialis - oblique fibres: • weak knee extensor • prominent activation in last 40º of knee extension • medial patella stabiliser - prevents vastus lateralis from laterally dislocating the patella • increases the efficiency of vastus lateralis in knee extension by realigning pull (required force decreased by 13%) (Mirzabeigi et al, 1999)

Question 32

what is the primary and secondary restraint for anterior tibial displacements

Answer 32

primary - ACL | secondary - medial collateral lig and iliotibial band

Question 33

what is the primary and secondary restraint for posterior tibial displacement

Answer 33

primary - PCL | secondary - medial collateral, lateral collateral and oblique popliteal

Question 34

what is the primary and secondary restraint for posterior tibial displacement

Answer 34

primary - PCL | secondary - medial collateral, lateral collateral and oblique popliteal

Question 35

what is the primary and secondary restraint for abduction (valgus) at the knee

Answer 35

primary - medial collateral | secondary - ACL, PCL, oblique popliteal lig

Question 36

what is the primary and secondary restraint for adduction (varus) at the knee

Answer 36

primary - not ligamentous | secondary - lateral collateral, posterolateral corner

Question 37

what is the primary and secondary restraint for internal tibial rotation

Answer 37

primary - medial collateral and posteromedial corner | secondary - ACL and PCL

Question 38

what is the primary and secondary restraint for external tibial rotation

Answer 38

posterolateral corner complex - which includes the lateral collateral and popliteal fibular ligament