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Functional Anatomy > Knee > Flashcards

Knee Flashcards

1
Q

Normal genu valgum

A
  • Slight medial angulation of the femur, horizontal tibial articular surface
  • Knee forms an angle on the lateral side of 170-175 (5-10 degrees of genu valgum)
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2
Q

Excessive genu valgum

A

15 degrees)

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3
Q

Genu varum

A

> 180 degrees in frontal plane

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4
Q

Three compartments of the knee

A
  1. Medial compartment (medial tibial plateau, meniscus, femoral condyle)
  2. Lateral compartment
  3. Patellofemoral compartment

^ Used to describe OA and TKA/ partial KA

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5
Q

Mismatch of surfaces of femur and tibia

A

Large convex femoral condyle

Smaller tibial plateaus

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6
Q

Meniscus function

A

“Gaskets” to improve joint congruity and stability
Shock absorption –> disperse load on articular cartilage to a wider surface area

Meniscus injury increases OA risk

Deform in weight bearing

Mobile: Move with the tibia. Lateral moves more than medial (more tears occur in medial)

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7
Q

Medial vs. lateral tibial plateau

A

Medial: Concave
Lateral: Mostly flat (Slightly concave)

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8
Q

Femoral condyles - medial vs. lateral

A

Lateral condyle is steeper

Femoral groove is aka trochlea

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9
Q

Thickest hyaline cartilage in the body?

A

Patella

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10
Q

Makeup of menisci

A

Fibrocartilage (like labrum, IVD)
- Large water content

Anchored in the intercondylar area
Coronary ligaments

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11
Q

Vascular and nerve supply to menisci

A
  • Inner 2/3 poorly vascularized, not innervated

- Outer 1/3: Vascular, innervated

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12
Q

Medial meniscus

A
  • C shaped
  • Less mobile than lateral
  • Attachments: Joint capsule, MCL, ACL at anterior horn, Semimembranosus at posterior horn

Attaches to MCL via menisco-tibial/ coronary ligaments

  • Body’s center of mass usually runs through medial compartment –> more tears
  • Varus malalignment is more common with degeneration (increases medial stress) –> more tears
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13
Q

Lateral meniscus

A
  • O shaped
  • More mobile (weaker capsular attachments)
  • No attachment to LCL
  • Attachments: PCL, Popliteus, medial mensicus (via transverse ligament in anterior knee)

Tears in lateral are less common than tears in medial

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14
Q

Meniscal Tear special tests

A

Thessaly
McMurray
Apley
Palpation for tenderness (more posterior than you think, along jt line)

None of these tests are great

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15
Q

Thessaly test

A

For meniscus tear

  • Pt stands on one leg
  • Pt flexes knee to 20 degrees, rotates body over knee
  • Repeat rotation 3 time in each direction

Positive: Joint-line pain and possibly a sense of locking or catching

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16
Q

McMurray’s Test

A

For meniscus tear

  • Pt in supine
  • Grasp heel and flex knee to EROM, using other hand to palpate jt line
  • Medial meniscus: ER tibia as knee is extended
  • Lateral meniscus: IR tibia as knee is extended

Positive: Audible or palpable thud or click

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17
Q

Apley’s Test

A

For meniscus tear

  • Pt in prone
  • Knee flexed to 90 degrees
  • Load menisci and twist (this is part 2 of test)

Part 1: distraction of tibia and twist

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18
Q

Swelling inside joint capsule

A

Effusion

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19
Q

Joint capsule and reinforcing ligaments

A

Anterior: Major contribution from medial and lateral patellar retinaculum

Posterior: Reinforced by oblique popliteal ligament and the arcuate popliteal ligament

Lateral: LCL, ITB, lateral patellar retinaculum, biceps, popliteal tendon

Medial: Patellar tendon to posterior capsule. MCL, medial patellar retinaculum

Posterior-medial capsule reinforces by pes

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20
Q

Synovial lining of capsule

A
  • Provides nourishment and lubrication to joint
  • Highly vascular and innervated
  • Lines capsule, except it wraps around cruciate ligaments and excludes them

–> Cruciates are intracapsular but extrasynovial

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21
Q

Plica

A

Thickening and fold of synovial lining

  • Remnants of synovial septa
  • Loose, pliant, elastic fibrous CT
  • Passes back and forth over femoral condyles as knee moves
  • Only issue when irritated

3 plica:

  1. Infrapatellar
  2. Suprapatellar
  3. Mediopatellar (most problems)
22
Q

Knee Bursae

A
  • Limit friction between muscles, bones, ligaments
  • Suprapatellar/ prepatellar bursa gets inflamed with direct trauma or lots of kneeling
  • Subpopliteal bursa distends in popliteal space with trauma or effusion
23
Q

Popliteal cyst

A

Side effect of joint effusion
- Produces outpouching of synovium in popliteal space

AKA Baker’s cyst

24
Q

Effusion

A
  • Pressure evenly distributed at 15-20 degrees of knee flexion
    Limits knee flexion - no limit to knee extension ROM
    –> Quad atrophy and shut down
25
Q

Vascular supply to cruciate ligaments

A

Poor (especially ACL)

26
Q

ACL

A
  • From posteromedial aspect of lateral femoral condyle to anterior intercondylar region of tiba
  • Prevents: Anterior tibial translation, rotation, varus/valgus forces in extension, hyperextension

2 bundles: Anterior medial and Posterior lateral

  • Extension: Both taught
  • Flexion: P-L bundle on slack
27
Q

Mechanism of ACL injury

A

Most are non-contact

  • often deceleration or landing from a jump
  • knee in 20-30 degrees flexion (ACL almost lax)
  • Hyperextension, falls, contact mechanisms also possible

Other structures often damaged:

  • Menisci, articular cartilage, MCL, lateral side complex, PCL
  • Bone bruises usually seen on MRI (LFC and lateral tibial plateau)
28
Q

ACL Tear special tests

A

Lachman’s
Anterior drawer
Others: Pivot shift, lelli’s test

Lachman: Supine, knee flexed 15 degrees
Ant. Drawer: Supine, knee flexed 90 degrees

29
Q

PCL

A
  • Broader and thicker than ACL
  • Lateral side of medial femoral condyle to posterior intercondylar area of tibia
  • Two bundles (Anterior lateral and posterior medial)
  • Knee flexion - complex twisting and changes in length and orientation

Tension is greatest between 90 and 120 degrees of flexion

30
Q

Mechanism of PCL injury

A
  • Fall onto front of knee, with ankle in full PF
  • Dashboard injury
  • Contact sports

Other structures are injured 50% of the time

31
Q

PCL Tear special tests

A

Posterior Drawer

Posterior Sage sign/ Godfrey’s test (Supine, legs at 90/90)

32
Q

Intercondylar Notch Width and cruciate tears

A
  • Size of cruciate ligaments is = size of intercondylar notch
  • Smaller notch, smaller ligaments, easier to tear
  • Notch width doesn’t correlate with height/ weight
  • Males have larger notches than females, on average
33
Q

MCL and LCL

A
  • Both tight in extension, relatively lax in flexion (Distance between attachment sites is smaller in flexion)
  • Taught in external rotation of tibia
34
Q

MCL

A
  • Flat and broad
  • Attachments to medial meniscus
  • Two components: Superficial and deep fibers (tears usually begin in deep fibers)
  • Limits valgus or abduction force

Proxmal tears: More stiff, but faster healing

35
Q

Valgus/ Varus Stress Test

A

For MCL/ LCL
- Pt in supine
- test in full extension and 30 degrees flexion
Block hip rotation with hand

  • if test is positive in extension, there is damage to jt capsule
36
Q

LCL

A
  • Cord like
  • No meniscal attachment
  • Posterior to IT band, anterior to biceps
  • Attaches to fibular head
  • Limits varus or ADD force. Stressed in figure 4 position (lateral capsule is also important in resisting varus force)

Only way to get isolated LCL sprain - forced figure 4 mechanism

37
Q

Lateral side complex

A

Resistance to varus stress is provided by 6 structures

  1. LCL
  2. Biceps tendon
  3. Lateral capsule
  4. ITB
  5. Lateral gastroc
  6. Popliteal
    - Injuries to complex are usually in combo with ACL/PCL, need surgery
38
Q

Knee joint motion

A

Average: 5-0-145

Axis of rotation: 2 cm above fibular head

Axis of rotation migrates posteriorly with flexion

OKC: Tibia glides posterior (Flex) and anterior (Ext)
CKC: Femur glides anterior and rolls posterior (flex), or glides posterior and rolls anterior (ext)

39
Q

Screw Home Rotation of knee

A
  • Locking knee into extension requires 10 degrees of tibial ER
  • Conjunct rotation
  • Driven by: Shape of medial femoral condyle, passive tension in ACL, slight lateral pull of quads
  • Condyle shape most important

When moving into flexion, popliteus unlocks knee by IR tibia

CKC: Locking = IR of femur

40
Q

Tibial Rotation

A

IR: 30
ER: 40

Limited rotation in extension (ligaments are tight, close packed)
Rotation is maximal at 90 degrees flexion
Occurs around axis that closely approximates course of PCL

Menisci distort with femoral condyles in WB, not really in non WB

41
Q

Two muscles that attach to AIIS

A
  • Rectus femoris

- Vastus intermedius

42
Q

Osgood Schlatter’s Disease/ Sinding-Larsen Johansson Disease

A

Traction apophysitis

  • Osgood: Tibial tubercle
  • SLJ: Distal pole patella

Rehab: Activity modification, patellar tendon strap, maintain LE flexibility

43
Q

Jumper’s Knee (Patellar Tendinopathy)

A

Inflammatory/ Degenerative condition of patellar tendon

  • Usually proximal tendon
  • Distal tendonitis can occur in distance runners

Treatment: Eccentric exercises

44
Q

Popliteus

A

Lateral femur, fibular head, and LM - courses medially to posterior tibia

OKC: Internally rotates tibia
CKC: Externally rotates femur

Attaches to Lateral Meniscus to move it out of the way as knee begins to flex

45
Q

IT Band

A

TFL and Glut Max –> Gerdy’s tubercle on proximal tibia

  • Resists varus stress at knee
  • Fibers connecting to patella can influence tracking of patella
  • Knee flexion 20: Assists knee flexion (depends where joint is relative to joint axis)
46
Q

ITB Syndrome

A
  • Irritation at LFC
  • Repetitive injury
  • Stress and friction –> inflammation

Rehab:

  • TFL, ham and quad flexibility
  • Hip and knee control
  • Inflammation care
47
Q

Structures resisting anterior tibial translation

A

ACL

Hamstrings, capsule, MCL, LCL

48
Q

Structures resisting posterior tibial translation

A

PCL,

Quads, Capsule, LCL

49
Q

Patella: Patellar tendon length

A

Normal ratio is 1:1

Patella baja: Low riding patella
Patella alta: High riding
–> Associated with instability

50
Q

Patellofemoral congruence

A
  • Most mobile in extension (quads relaxed)
  • Compression increased posteriorly and laterally with increased force through joint
  • Most stable in the trochlear groove (in flexion)
51
Q

Medial patellar stabilization provided by:

A

VMO
Medial retinaculum
Steep lateral femoral condyle
Medial Patellofemoral Ligament

52
Q

Lateral Pull of patella is a result of

A

Large q angle
Tight lat. retinaculum/ ITB
Increased force IR
Weak VMO

Functional Anatomy (14 decks)

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