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204-theme 2 -anatomy > l15:anatomy of the knee > Flashcards

l15:anatomy of the knee Flashcards

1
Q

what is the articulation between the distal femur and proximal tibia

A

The knee aka synovial bicondylar hinge joint

Articulation between femur and patella

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2
Q

what are the functions of the knee

A

-Weight-bearing

  • Mobility
  • -extension/flexion
  • -some rotation when flexed
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3
Q

what are the different factors that help improve stability and strength

A

Bony factors:

  • Bony expansions
  • Locking mechanism
  • Femoral angle

Soft tissue factors:

  • Ligaments
  • Menisci
  • Muscles
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4
Q

go over bony expansions and what they provide for the leg

A

intercondylar fossa

tibial condyles

epicondyles

femoral condyles

Provides a strong base

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5
Q

locking mechanism 1: describe the shape of the femur

A
  • in flexion:- femoral surfaces round

- in extension- femoral surfaces flat

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6
Q

locking mechanism 2 : describe rotation of the knee

A

Medial rotation of femur on tibia in extension

- Tightens ligaments of the knee

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7
Q

locking mechanism 3 :describe the centre of gravity

A

Centre of gravity in front of knee

- Maintains extension

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8
Q

what is the importance of the femoral angle

A

Adducted femur brings knee joint under pelvis

Critical for weight bearing

Occurs during development

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9
Q

what is the femoral angle made up of

A
  • anatomical axis
  • mechanical axis
  • forming the Q angle
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10
Q

what is the normal alignment of the knee

A

Normal alignment of joint (mechanical axis) :
Vertical line through centre of femoral head,
centre of knee and centre of ankle

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11
Q

what is the anatomical axis and mechanical axis

A

Anatomical: follows Asis

mechanical: vertical line through centre of femoral head, centre of knee and centre of ankle

where weight and force are distributed

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12
Q

describe the varus deformity Genu Varum

A

Deformity in the angle between femur and tibia

Medial displacement of the tibia
- Common in children under 2, rickets

Pushes knees apart - ‘Bow-legged’= Decrease in Q angle

caused by increased stress which causes joint degeneration

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13
Q

describe Valgus deformity (Genu valgum)

A

Lateral displacement of the tibia
- Common in children aged 2-4, rickets, arthritis

Brings knees together - ‘Knock-kneed’
= Increase in Q angle

the stress also results in joint degeneration

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14
Q

what are the ligaments of the knee

A

2 groups:

Extracapsular – outside capsule

	- Medial collateral 
	- Lateral collateral

&

Intracapsular – inside capsule

	- Anterior cruciate
	- Posterior cruciate
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15
Q

describe the lateral/fibular collateral ligament

A

Strong round cord

- Prevents medial displacement of tibia

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16
Q

what does a tear in the LCL cause

A

Tear of LCL = Varus deformity (medial)

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17
Q

describe the Medial/tibial collateral ligament

A

Broad flat band

  • Reinforces joint capsule
  • Prevents lateral displacement of tibia
18
Q

what does a tear of the MCL cause

A

= Valgus deformity (lateral)

19
Q

what is the intracapsular ligament

A

divided into the anterior cruciate ligament

  • posterior cruciate ligament
  • anterior and posterior in relation to tibia
20
Q

what is the function of the posterior and anterior cruciate

A

Anterior cruciate
- Prevents anterior displacement of tibia on femur

Posterior cruciate
- Prevents posterior displacement of tibia on femur

Maintain femur against tibia
-Always one ligament tense

21
Q

describe the cruciate ligaments

A

look at slide 16

22
Q

what is the Lachman test

A

Patient in supine position with knee bent 20-300 of flexion

  • Move tibia anteriorly and posteriorly while maintaining position of femur
  • Laxity during this manoeuvre indicates anterior cruciate ligament injury
23
Q

what happens with the weakness of Anterior cruciate ligament

A

Weaker - can become injured

  • Common sports injury
  • Caused by sharp twisting of knee
  • Immediate decreased range of movement
24
Q

does the posterior cruciate ligament

A

Stronger - Rarely injured

  • Principle stabilizer when knee flexed
25
Q

describe the menisci of the joint

A

Crescent-shaped plates of fibrocartilage

- Deepen the articulating surfaces/stability
- Shock absorbers
- Provides smooth viscous film for joint
26
Q

what are the menisci attachments

A

Horns of menisci attached to intercondylar area of tibia

Mobile - Accommodates rolling of femoral condyles

Medial meniscus less mobile
- Attached to medial collateral ligament

27
Q

what is the unhappy triad

A 
Twisting on a flexed knee/blow to lateral side
Contact sports (rugby tackle)
Locking of the knee 
Rupture:
- Anterior cruciate ligament
- Medial collateral ligament
- Medial meniscus (attached to MCL)
28
Q

what is the iliotibial tract

A

Iliotibial tract
- Reinforces joint capsule

  • Stabilizes extended knee
    (gluteus maximus, tensor fascia lata)
29
Q

what muscles are involved in extension of the leg

A

Quadriceps extends leg

Major stabilizing muscle of the knee

4 heads - Rectus femoris
Vastus lateralis
Vastus intermedialis

look at slide 24
Vastus medialis

30
Q

what is the extensor mechanism

A

Patella

  • Protects quadriceps tendon from stresses during locomotion
  • Smooth oval facet of posterior surface for articulation with femur
  • Lateral patellar retinaculum
  • Medial patellar retinaculum
31
Q

what is the extensor mechanism injury

A

Rupture of quadriceps tendon or patellar ligament

Fracture of the patella
- Due to fall or blow to knee

  • Results in loss of active extension

Dislocation of patella common
- Due to sudden twisting/jumping or ligamentous laxity

32
Q

what are the flexors of the leg

A

Hamstrings and gastrocnemius flex leg

Hamstrings actually three muscles:

  • Biceps femoris
  • Semimembranosus
  • Semitendinosus
  • Also medially and laterally rotates leg when knee flexed
  • And extends thigh
33
Q

describe unlocking of extended leg

A
  • Popliteus unlocks the knee joint

- Laterally rotates femur on tibia when foot is on ground

34
Q

what is the synovial membrane

A

From margins of articular surfaces of femur to tibia

Attached to patella

Extends superiorly behind quadriceps tendon

Cuffs anterior surface of cruciate ligaments

35
Q

describe the bursae

A

Synovial fluid filled sac lined by synovial membrane

  • Protection
  • Reduce friction
36
Q

describe other bursae

A

32

37
Q

describe bursitis

A

Inflammation of bursae
Due to repetitive movements or direct pressure

Prepatellar bursitis (‘housemaid’s knee’)
- Seen in carpet fitters
  • Leaning forward on the knees brings the prepatellar bursa in contact with floor
38
Q

describe Infrapatellar bursitis (‘clergyman’s knee’)

A
  • After prolonged periods of prayer clergymen sat back on their heels bringing infrapatellar bursa in contact with floor
39
Q

describe the Bakers (popliteal) cyst

A

Abnormal fluid filled sacs in popliteal fossa
- Due to herniation of synovial membrane/bursa

Common in patients with chronic
inflammatory joint disease (e.g. arthritis)

  • Presents as swelling in the popliteal fossa
  • Can affect joint movement
40
Q

describe the vascular supply

A

Anastomosis around knee
- Femoral artery

  • Popliteal artery

Limited blood supply to intracapsular structures
- Poor repair following injury

204-theme 2 -anatomy (15 decks)

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