Knee Anatomy, Pathomechanics - PowerPoint Presentation

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Knee Anatomy, Pathomechanics, Evaluation, & Treatment

Gary Wilkerson,

EdD, ATC

Student SEATA

2017

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2Knee Anatomy – Anterior View

Medial Collateral Lig. (16)Lateral Collateral Lig. (6)Anterior Cruciate Lig. (1)

Posterior Cruciate Lig. (14)Medial Mensicus (12)

Lateral Meniscus (9)Coronary Ligaments (11)Ant. Meniscofemoral Lig. (2)

(Ligament of Humphry)

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3Knee Anatomy - Posterior View

Medial Collateral Lig. (16)Lateral Collateral Lig. (6)

Anterior Cruciate Lig. (1)Posterior Cruciate Lig. (14)

Medial Mensicus (12)Lateral Meniscus (9)Post. Meniscofemoral Lig. (15)

(Ligament of Wrisberg)

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4Menisco-Femoral Ligaments

aMFL = Ligament of HumphrypMFL = Ligament of Wrisberg

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5

Knee Anatomy

Postero

-MedialPosterior Oblique

Lig

.

Postero

-Lateral

Arcuate

Lig

. & Oblique

Popliteal

Lig

.

PosteriorOblique Ligament

Arcuate Ligament

Oblique Popliteal Ligament

Slide6

6Clinical Evaluation of the Knee

HistoryMechanism of Injury

Inspection

Hemarthrosis vs. “Watery” EffusionPalpation

Location of Point Tenderness

ROM

Active & Passive

Neurovascular Status

Circulation & Sensation

Special Tests

Ligament & Meniscus Pathology

Slide7

7History

Mechanism of Injury

Uniplanar Blow/Displacement

Isolated injuryMultiplanar and/or Rotational Displacement

Multiple injuries

Associated Sounds/Sensations

“

Pop” or “Snap”

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8Lower Extremity Alignment

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9Acute Injuries

Muscle Strain

Gastrocnemius

Plantaris

Popliteus

Contusions

Quadriceps

Femoral

condyle

Infrapatellar

fat pad

Traumatic Bursitis

Prepatellar

Suprapatellar

Pes

Anserine

Infrapatellar

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10Medial Collateral Ligament Tear

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11Epiphyseal Fracture

Difficult to distinguish from collateral ligament injury!

Slide12

12“Unhappy Triad”

ACL + MCL + Lateral Meniscus Tear

?

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13ACL Tear

Female athletes experience 4-8X greater incidence of non-contact ACL tear Proposed risk factors:

Lower extremity weakness/fatigue

Low H/Q strength ratioSubtalar joint pronation

Anterior pelvic tilt

Large Q-angle

Genu

recurvatum

Effects of estrogen & progesterone

Narrow

intercondylar

notch

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14Intercondylar Notch Width

NWI =

0.27

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15Male vs. Female Lower Extremity Alignment

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16Non-Contact ACL Injury Mechanisms

Valgus

+ External Rotation of Tibia

Varus + Internal Rotation of TibiaHyperextension + ER or IR of Tibia

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ACL – Intercondylar Shelf17

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18Sagittal Plane MRI

Normal ACL

Torn ACL

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19ACL Reconstruction

Allograft – derived from cadaver tissueAutograft – derived from patient’s body

Patellar tendonHamstring tendon

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20

Varus

Alignment + ACL Injury

Isolated LCL injury is rare!

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21Rotational Instability

Combinations of Translation/RotationAnteromedial

ACL + MCLAnterolateral

ACL (+LCL)Posteromedial

PCL + MCL

Posterolateral

PCL + LCL

LATERAL

MEDIAL

ANTERIOR

POSTERIOR

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ACL-PCL Relationship22

Slide23

23PCL Tear

Tibia forced posteriorlyCommon mechanisms

Falling on tibial tuberosity

of flexed kneeCar dashboard impact against flexed kneeAnterior blow to tibia with knee hyperextension

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24Meniscus Function

Medial

“C”

Lateral

“O”

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Meniscus Tears

25

Slide26

26Meniscus Tears

Pain, swelling, and joint line tenderness

Displaced mensicus tear

Limited extension and/or flexion Clicking and/or locking

Posterior horn tear

Posterior knee pain

Pain with deep knee squatting

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27

Popliteal

“Baker’s” Cyst

Fluid-filled cyst

Infero

-medial

popliteal

fossa

May or may not be tender

Commonly associated with meniscus tear

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28Arthroscopic Menisectomy

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Meniscus Tear - OA29

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30Osteochondral

FractureOsteochondrosis Dissecans

(OCD)Avascular necrosis

80%: medial femoral condyle3X greater incidence in malesNon-localized pain

Clunking sensation

Knee locking

Giving-way

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31Nerve & Vascular Injuries

Peroneal Nerve PalsyDirect blow

Traction (varus)Cryotherapy

numbness, burning, and/or tinglinglateral aspect of the lower leg & dorsum of foot

weakness of

dorsiflexers

,

everters

, & toe extensors

foot drop

Slide32

32Knee Dislocation

Limb-threatening injurySpontaneous reduction may occur

Multiple ligaments torn

Neurovascular damage should be suspectedPopliteal artery

Tibial

nerve

Slide33

Osgood-Schlatter Syndrome

Apophysis TractionTenderness over tibial tuberosity

Pain increased with extension exercises, squatting, kneeling, & jumping

Slide34

34Sinding

-Larsen-Johansson SyndromePatellar tendon degeneration (tendinosis) at attachment to inferior pole of patella

Caused by repetitive forces associated with running and jumping

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IT Band Friction SyndromeFriction between IT band & lateral femoral

condyle @ ≈30º flexion

Predisposing factorsgenu

varum (bow-legged)foot pronation

leg length discrepancy

IT band tightness

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36Knee Plica

Embryologic soft tissue remnant

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Patello-Femoral Joint37

Slide38

38Bipartite

Patella

Slide39

39Patella

Subluxation/Dislocation

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40Lateral

Patello-Femoral Pain Syndrome

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Q-Angle41

ExcessiveMales >15° (Average ~13°)

Females >20° (Average ~18

°)

10

°

26°

Slide42

42Chondromalacia

PatellaSoftening/degeneration of articular cartilage on patella undersurface.

Pain elicited by resisted knee extensionGrinding sensation (crepitus

)Post-activity effusion

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43Patello

-Femoral Osteoarthritis

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44Patello-Femoral Compression

Hamstring tightness increases P-F compression

ITB tightness can cause lateral pressure concentration

Slide45

Lateral P-F Retinaculum & IT Band

SUPERFICIAL

DEEP

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46ACL-R Rehab Complications

Sachs et al, AJSM, 1989

Slide47

47Lack of Full Extension

Synovial Hypertrophy – Cyclops Lesion

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48Anterior vs. Posterior

Tibial TranslationEffect of Quadriceps – Patellar Tendon

65

°

65

°

Slide49

49

Slide50

50Articular Cartilage Lesions

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51

Bone Bruise:

Lateral Femoral

Condyle

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52Osteochondral

Autograft Transfer System: “OATS” (Arthrex, Inc.)

“

Mosaicplasty

”

Slide53

53Autologous

Chondrocyte Implantation

Slide54

54Acute Knee Injuries

Ligament Sprain/RuptureIsolated vs. Combined Ligament Lesions

MCL – ACL – LCL – Arcuate Complex – PCL

Meniscus TearLateral – Medial Peripheral vs. Mid-Substance LesionPatella Subluxation

– Fracture

Articular

Surface Lesion –

Osteochondral

Fx

Muscle Strain

Neurovascular Injury

Slide55

55Chronic Knee Conditions

Patello-Femoral Pain – Chrondromalacia

TendinosisPatellar Tendon – IT Band – Hamstrings Tendons

BursitisPes Anserinus – Baker’s Cyst –

Infrapatellar

Osgood-

Schlatter’s

Syndrome

Osteoarthritis

Slide56

56Clinical Evaluation

History

Mechanism of InjuryInspection

Hemarthrosis vs. “Watery” EffusionPalpation

Location of Point Tenderness

ROM

Active & Passive

Neurovascular Status

Circulation & Sensation

Special Tests

Ligament & Meniscus Pathology

Slide57

57Valgus /

Varus Stress TestsValgus

/ Varus stress applied both in full extension and 20 ° of flexion

Slide58

58Knee Collateral Ligament Laxity Testing

Valgus

Test

Varus

Test

Slide59

59Anterior-Posterior Drawer Tests

Drawer Test

Slide60

60ACL Laxity Tests

Lachman

Test

Pivot Shift Test

Slide61

61PCL Tear: Tibial

Sag Test

Slide62

62KT-1000 Arthrometer

Evaluation of ACL restraint of anterior tibial displacement

15 / 20 / 30 lb. pull> or < 3 mm difference

Slide63

63Tests for Meniscus Tear

McMurray Test

Thessaly Test

Apley

Test

Slide64

64How accurate are special tests?

True Status

Positive

True Status

Negative

Clinical Test “Positive”

FOUND IT

(True-Positive)

FALSE ALARM

(False-Positive)

Clinical Test “Negative”

MISSED IT

(False-Negative)

ALL CLEAR

(True-Negative)

Sensitivity

Specificity

What % of cases are correctly classified by clinical test finding?

Slide65

65Sensitivity

of a Clinical Test(True-Positive Rate)

Positive identification when condition exists

ACL tornHigh degree of agreement with “gold standard”Arthroscopic diagnosis of ACL tear

Low rate of clinical test false negatives (failure to identify)

Anterior Drawer: 41%

Lachman

: 82%

Sensitivity = # True-Positive

/

(# True-Positive + # False-Negative)

Slide66

66Specificity

of a Clinical Test(True-Negative Rate)

Exclusion of a condition when it does not

existACL intact

High degree of agreement with “gold standard”

Arthroscopic confirmation of intact ACL

High rate of clinical test true negatives (correct exclusion)

Anterior Drawer: 95%

Lachman

: 97%

Specificity = # True-Negative / (# True-Negative + # False-Positive)

Slide67

67Likelihood Ratios

The probability that a condition exists “prior” to performance of a clinical test is modified by the test result to

“posterior” probabilityPositive test result: Positive Likelihood Ratio (+LR)

Negative test result: Negative Likelihood Ratio (-LR)

Gold Standard

Positive

Gold Standard

Negative

Likelihood Ratio

Clinical Test Positive

True Positive

Rate

False Positive Rate

+LR =

TPR

/ FPR

Clinical Test Negative

False Negative Rate

True Negative Rate

-

LR =

FNR /

TNR

Slide68

Likelihood Ratio Interpretation+LR2.0 =

2/1 = 2 X greater3.0 = 3/1 = 3 X greater

4.0 = 4/1 = 4 X greater

5.0 = 5/1 = 5 X greater10.0 = 10/1

= 10 X greater

20.0 =

20/1

= 20 X greater

–LR

0.50 =

1/2

= 2 X lower

0.33 =

1/3

= 3 X lower

0.25 =

1/4

= 4 X lower

0.20 =

1/5

= 5 X lower

0.10 =

1/10

= 10 X lower0.05 = 1/20 = 20 X lower

68

Slide69

69Anterior Drawer Test

Hip flexed at 45°, knee flexed at 90° With both thumbs placed on the joint line, the tibia is gently drawn forward

Excursion of the tibia is compared with the unaffected side

High

TNR

Study

Sensitivity

Specificity

+LR

–LR

OR

van Eck et al, 2013

38%

81%

2.00

0.77

2.60

Benjaminse

et al, 2006

55%

92%

6.88

0.49

14.04

Scholten

et al, 2003

62%88%5.170.4312.02Jackson et al, 200348%

87%3.690.88 4.19Solomon et al, 200162%67%1.880.57 3.30Katz & Fingeroth, 198641%

95%

8.20

0.62

13.23

Low TPR

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70Lachman Test

15° - 30° of knee flexion

The femur is stabilized with one hand and the tibia is gently drawn forward with the opposite hand

(+) = Anterior translation of tibia with “soft” or “mushy” endpoint

Study

Sensitivity

Specificity

+LR

–LR

OR

van Eck et al, 2013

81%

81%

4.26

0.23

18.52

Benjaminse

et al, 2006

85%

94%

14.17

0.16

88.56

Scholten

et al, 2003

85%

91% 9.440.16 59.00Jackson et al, 200387% 93%12.430.14 88.79Solomon et al, 200184%100%

-0.16∞Katz & Fingeroth, 198682% 97%27.330.19143.84

High

TNR

High TPR

Slide71

71Pivot Shift Test

Foot internally rotated while applying a gentle valgus stress to the knee

Knee is then slowly brought into flexion

(+) = “Shift” felt with subluxation/reduction of the lateral tibial plateau anteriorly

as knee is brought into further flexion

Study

Sensitivity

Specificity

+LR

–LR

OR

van Eck et al, 2013

28%

81%

1.47

0.89

1.65

Benjaminse

et al, 2006

24%

98%

12.00

0.78

15.38

Jackson et al, 2003

61%

97%20.330.40

50.83Katz & Fingeroth, 198681%98%40.500.19213.16

Slide72

Probability ShiftBefore Test – After Test

72Likelihood that ACL tear exists -

Test

Positive Result +LR

Negative Result

–

LR

Odds Ratio

+LR /

–

LR

Anterior

Drawer

~3

X greater

~.

6 (1.7 X lower)

~5

Lachman

~12

X greater

~.

2 (5 X lower)

~70

Pivot Shift

~7

X greater

~.5 (2

X lower)

~14

Slide73

Pain elicited by palpation of joint line73

Joint Line Tenderness

Study

Sensitivity

Specificity

+LR

–LR

OR

Smith et al, 2015

83%

83%

4.88

0.20

24.40

Meserve

et al,

2008

76%

77%

3.30

0.31

10.65

Hegedus

et al, 2007

63%

77%2.740.48 5.71Jackson et al, 200376%29%

1.070.83 1.29Solomon et al, 200179%15%0.931.40 0.66Stratford & Binkley, 199575%27%1.03

0.93 1.11Fowler & Lubliner, 198985%30%1.210.50 2.42

50/50

Toss a coin!

Slide74

Study

Sensitivity

Specificity

+LR

–LR

OR

Meserve

et al,

2008

22%

80%

1.10

0.98

1.12

Hegedus

et al, 2007

61%

70%

2.03

0.56

3.63

Fowler &

Lubliner

, 1989

16%

80%0.801.050.7674Apley TestIn the prone position, apply a pressure at the sole of the foot toward the examination table.

Tibia is rotated both externally and internallyThe tibia is then distracted while being rotated once more(+) = Patient experiences decreased pain with the distraction maneuver as compared to the compression maneuver

Very Low True Positive Rate50/50Toss a coin!

Slide75

75McMurray Test

Knee is flexed and placed in external rotationExaminer applies a

valgus or varus force

Knee is then extended. (+) = Pain and/or a popping/ snapping sensation

Study

Sensitivity

Specificity

+LR

–LR

OR

Smith et al, 2015

61%

84%

3.81

0.46

8.28

Meserve

et al, 2008

55%

77%

2.39

0.58

4.12

Ryzewicz

et al, 2007

16%

69% 0.521.22 0.43Hegedus et al, 200771%71% 2.45

0.41 5.98Jackson et al, 200352%97%17.330.4935.37Solomon et al, 200153%59% 1.290.80

1.61

Stratford & Binkley, 1995

52%

97%

17.33

0.49

35.37

Fowler &

Lubliner

, 1989

29%

96%

7.25

0.74

9.80

High

TNR

Low TPR

Slide76

Thessaly TestActive internal and external rotation of femur on weight-bearing extremity20° knee flexion – 3 repetitions

Positive = medial or lateral discomfort76

SENSITIVITY SPECIFICITY

+

LR

-

LR 90% 98%

39.30

0.09

Harrison et al. The Thessaly test for detection of meniscal tears: validation of a new physical examination technique for primary care medicine.

Clin

J Sport Med

. 2009

OR=393

Harrison et al

, 2009

Slide77

Lelli Lever Test77

Fist used as a fulcrum under the calf musculatureDownward manual pressure on quadricepsACL Intact = Knee Extension

ACL Torn = Foot Does Not Rise

Lelli

et al. The “Lever Sign”: a new clinical test for the diagnosis of anterior cruciate ligament rupture.

Knee

Surg

Sports

Traumatol

Arthrosc

. 2014

SENSITIVITY SPECIFICITY

+

LR

-

LR

86%

91%

37.26

0.10

Thapa

et al, 2015OR=376

Slide78

78Summary

Things you need to know:

Anatomy (Ligaments)

Injury Risk FactorsAcute Injury MechanismsOveruse Syndromes

Evaluation Procedures (Special Tests)

Rehabilitation Considerations