THE KNEETHE KNEE

The Knee JointThe Knee Joint

Knee jointKnee joint• largest largest

joint in joint in bodybody

• very very complexcomplex

• primarily a primarily a hinge jointhinge joint

BonesBones

Enlarged femoral condyles articulate Enlarged femoral condyles articulate on enlarged tibial condyleson enlarged tibial condyles

Medial & lateral tibial condyles (medial Medial & lateral tibial condyles (medial & lateral tibial plateaus) - receptacles & lateral tibial plateaus) - receptacles for femoral condylesfor femoral condyles

Tibia – medialTibia – medial• bears most of weightbears most of weight

BonesBones

Fibula - lateralFibula - lateral• serves as the serves as the

attachment for attachment for knee joint knee joint structuresstructures

• does not does not articulate with articulate with femur or patellafemur or patella

• not part of knee not part of knee jointjoint

BonesBones

PatellaPatella• sesamoid (floating) bonesesamoid (floating) bone• imbedded in quadriceps imbedded in quadriceps

& patellar tendon& patellar tendon• serves similar to a pulley serves similar to a pulley

in improving angle of in improving angle of pull, resulting in greater pull, resulting in greater mechanical advantage in mechanical advantage in knee extensionknee extension

JointsJoints

Knee joint proper (tibiofemoral joint)Knee joint proper (tibiofemoral joint)• classified as a ginglymus jointclassified as a ginglymus joint

Sometimes referred to as trochoginglymus Sometimes referred to as trochoginglymus joint internal & external rotation occur joint internal & external rotation occur during flexionduring flexion

Some argue for condyloid classificationSome argue for condyloid classification

Patellofemoral jointPatellofemoral joint• arthrodial classification arthrodial classification • gliding nature of patella on femoral gliding nature of patella on femoral

condylescondyles

Tibiofemoral jointTibiofemoral joint characteristics:characteristics: - anterior and posterior stability is - anterior and posterior stability is

by the anterior and posterior cruciate ligamentsby the anterior and posterior cruciate ligaments

medial and lateral stability is provided by the medial medial and lateral stability is provided by the medial and lateral collateral ligamentsand lateral collateral ligaments

the medial femoral condyle is longer than the lateral the medial femoral condyle is longer than the lateral femoral condyle, this contributes to external femoral condyle, this contributes to external rotation of the tibia at full knee extension which rotation of the tibia at full knee extension which locks the knee(screw - home mechanism)locks the knee(screw - home mechanism)

the concave tibial plateaus are covered by the the concave tibial plateaus are covered by the menisci, the medial plateau is larger that the lateral.menisci, the medial plateau is larger that the lateral.

the tibia rotates externally at full knee extension in the tibia rotates externally at full knee extension in open kinematic chain open kinematic chain movement.movement.

Tibiofemoral JointTibiofemoral Joint

the femur rotates internally on the the femur rotates internally on the tibia in full extension in the closed tibia in full extension in the closed kinematic chain. (foot on the kinematic chain. (foot on the ground).ground).

Screw home mechanismScrew home mechanism

Knee “screws home” to fully extend due to Knee “screws home” to fully extend due to the shape of medial femoral condylethe shape of medial femoral condyle• As knee approaches full extension tibia must As knee approaches full extension tibia must

externally rotate approximately 10 degrees to externally rotate approximately 10 degrees to achieve proper alignment of tibial & femoral achieve proper alignment of tibial & femoral condylescondyles

• In full extensionIn full extension close congruency of articular surfacesclose congruency of articular surfaces no appreciable rotation of kneeno appreciable rotation of knee

• During initial flexion from full extensionDuring initial flexion from full extension knee “unlocks” by tibia rotating internally, to a knee “unlocks” by tibia rotating internally, to a

degree, from its externally rotated position to degree, from its externally rotated position to achieve flexion achieve flexion

Patellofemoral joint Patellofemoral joint characteristics:characteristics:

patella articulates with the intercondylar patella articulates with the intercondylar (trochlear)groove on the anterior aspect of the (trochlear)groove on the anterior aspect of the femur.femur.

the patella slides inferiorly with knee flexion and the patella slides inferiorly with knee flexion and superiorly with knee extension.superiorly with knee extension.

patella comes in contact with the femur at patella comes in contact with the femur at approximately 20 -30 degrees of kneeflexion. As approximately 20 -30 degrees of kneeflexion. As flexion increases contact on patella goes flexion increases contact on patella goes superiorly and ends on the odd facet (medial) at superiorly and ends on the odd facet (medial) at 135 degrees of flexion.135 degrees of flexion.

Tibial and femoral rotation can affect the Tibial and femoral rotation can affect the alignment of this joint and cause pathology of alignment of this joint and cause pathology of the patella or femur's articular cartilage. the patella or femur's articular cartilage.

Factors to be considered at the Factors to be considered at the patella femoral joint:patella femoral joint:

Q angle is normally 15 degrees. measured by a Q angle is normally 15 degrees. measured by a line drawn from the center of the patella proximally line drawn from the center of the patella proximally to the ASIS and a second line drawn from the to the ASIS and a second line drawn from the center of the patella distally to the tibial tubercle center of the patella distally to the tibial tubercle

the patellar alignment is maintained by the iliotibial the patellar alignment is maintained by the iliotibial band and the lateral band and the lateral retinaculum (laterally) and retinaculum (laterally) and the pull of the vastus medialis (medially).the pull of the vastus medialis (medially).

malalignment of the patella can be caused by genu malalignment of the patella can be caused by genu valgum, wide pelvis, patella alta, lax medial valgum, wide pelvis, patella alta, lax medial retinaculum, atrophy of Vmo, laterally placed tibial retinaculum, atrophy of Vmo, laterally placed tibial tubercle, pronation of the subtalar joint and tight tubercle, pronation of the subtalar joint and tight lateral retinaculum.lateral retinaculum.

Patella AltaPatella Alta• high riding patellahigh riding patella

Patella BahaPatella Baha• low riding patellalow riding patella

Tibiofemoral JointTibiofemoral Joint Ligaments provide static stabilityLigaments provide static stability Quadriceps & hamstrings contractions produce dynamic Quadriceps & hamstrings contractions produce dynamic

stabilitystability Articular cartilage surfaces on femur & tibiaArticular cartilage surfaces on femur & tibia

Menisci FunctionsMenisci Functions

attached to tibia attached to tibia • deepen tibial fossadeepen tibial fossa• enhance stability enhance stability • - shock absorber- shock absorber• - spreading stress over joint surface- spreading stress over joint surface• - decreasing cartilage wear- decreasing cartilage wear• - lubricate and provide nutrients to the joint- lubricate and provide nutrients to the joint• - reduce friction during movement- reduce friction during movement

MeniscusMeniscus

CartilageCartilage• Medial MeniscusMedial Meniscus• Lateral MeniscusLateral Meniscus• Articular CartilageArticular Cartilage

Medial MeniscusMedial Meniscus

Medial meniscus forms receptacle for Medial meniscus forms receptacle for medial femoral condyle, Lateral meniscus medial femoral condyle, Lateral meniscus receives lateral femoral condylereceives lateral femoral condyle• Thicker on outside border & taper down very Thicker on outside border & taper down very

thin to inside borderthin to inside border• Can slip about slightly, but held in place by Can slip about slightly, but held in place by

various small ligamentsvarious small ligaments• Medial meniscus - larger & more open Medial meniscus - larger & more open CC

appearanceappearance• Lateral meniscus - closed Lateral meniscus - closed CC configuration configuration

MenisciMenisci

MedialMedial• the medial meniscus is firmly attached the medial meniscus is firmly attached

to the tibia by the coronary ligament, to the tibia by the coronary ligament, medial collateral ligament, anterior medial collateral ligament, anterior

cruciate ligament, semimembranosus.cruciate ligament, semimembranosus.• more subject to injury because of more subject to injury because of

attachmentsattachments• thicker posteriorly than anteriorlythicker posteriorly than anteriorly

MenisciMenisci

• Either or both menisci may be torn Either or both menisci may be torn in several different areas from a in several different areas from a variety of mechanisms, resulting variety of mechanisms, resulting in varying degrees of problemsin varying degrees of problemsTears often occur due significant Tears often occur due significant

compression & shear forces during compression & shear forces during rotation while flexing or extending rotation while flexing or extending during quick directional changes in during quick directional changes in runningrunning

Knee LigamentsKnee Ligaments LigamentsLigaments

• Medial Collateral Medial Collateral • Lateral Collateral Lateral Collateral • Anterior Cruciate Anterior Cruciate • Posterior CruciatePosterior Cruciate

Cruciate LigamentsCruciate Ligaments

Anterior & posterior cruciate ligamentsAnterior & posterior cruciate ligaments• cross within knee between tibia & femurcross within knee between tibia & femur• vital in respectively maintaining anterior & vital in respectively maintaining anterior &

posterior stability, as well as rotatory stabilityposterior stability, as well as rotatory stability Anterior cruciate ligament (ACL) injuriesAnterior cruciate ligament (ACL) injuries

• one of most common serious injuries to kneeone of most common serious injuries to knee• mechanism often involves noncontact rotary mechanism often involves noncontact rotary

forces associated with planting & cutting, forces associated with planting & cutting, hyperextension, or by violent quadriceps hyperextension, or by violent quadriceps contraction which pulls tibia forward on femur contraction which pulls tibia forward on femur

ACLACL prevents anterior displacement of the tibia on the prevents anterior displacement of the tibia on the

femur and checks internal rotation of the tibia on femur and checks internal rotation of the tibia on the femur.the femur.

attaches to the anterior medial tibia and runs attaches to the anterior medial tibia and runs superiorly, posteriorly and superiorly, posteriorly and laterally to the laterally to the medial aspect of the lateral femoral condylemedial aspect of the lateral femoral condyle

ACLACL

helps control rolling and gliding of helps control rolling and gliding of the femur during knee movementthe femur during knee movement

ACL is taught in all positions of knee ACL is taught in all positions of knee motion, with greatest tension in full motion, with greatest tension in full extensionextension

least taught at 30-60 deg of flexionleast taught at 30-60 deg of flexion

PCLPCL

Posterior cruciate Posterior cruciate ligament (PCL) ligament (PCL) injuriesinjuries• not often injurednot often injured• mechanism of direct mechanism of direct

contact with an contact with an opponent or playing opponent or playing surface driving tibia surface driving tibia posteriorposterior

PCLPCL

runs form the posterior intercondylar area runs form the posterior intercondylar area of the tibia forward medial and upward to of the tibia forward medial and upward to the lateral aspect of the medial femoral the lateral aspect of the medial femoral condylecondyle

prevents posterior displacement of the prevents posterior displacement of the tibia on the femurtibia on the femur

twists around the ACL with internal tibial twists around the ACL with internal tibial rotationrotation

acts as center axis of rotationacts as center axis of rotation

Medial Collateral LigamentMedial Collateral Ligament Two layers:Two layers: deep layer is a thickening of the deep layer is a thickening of the

medial joint capsulemedial joint capsule

superficial layer is a strong broad superficial layer is a strong broad triangular band that run from just triangular band that run from just below the adductor tubercle to below the adductor tubercle to about 4-6cm below the medial about 4-6cm below the medial joint linejoint line

checks valgus and external checks valgus and external rotation of the tibia on the femur rotation of the tibia on the femur most taut in full extensionmost taut in full extension

attaches to the medial meniscusattaches to the medial meniscus

Medial Collateral LigamentMedial Collateral Ligament

Tibial (medial) collateral ligament Tibial (medial) collateral ligament (MCL)(MCL)• injuries occur commonly, particularly in injuries occur commonly, particularly in

contact or collision sports contact or collision sports • mechanism of teammate or opponent may mechanism of teammate or opponent may

fall against lateral aspect of knee or leg fall against lateral aspect of knee or leg causing medial opening of knee joint & causing medial opening of knee joint & stress to medial ligamentous structuresstress to medial ligamentous structures

Lateral Collateral LigamentLateral Collateral Ligament round band of round band of

fibers running fibers running from the lateral from the lateral femoral femoral epicondyle to the epicondyle to the fibular headfibular head

tight on extension tight on extension of the knee, of the knee, adduction and adduction and external rotation external rotation of the tibia on the of the tibia on the femurfemur

LigamentsLigaments Arcuate and Arcuate and

Popliteal complexPopliteal complex• thickening of the thickening of the

capsule in the posterior capsule in the posterior lateral aspectlateral aspect

Posterior oblique Posterior oblique ligamentligament• help support the help support the

posterior medial aspect posterior medial aspect of the kneeof the knee

Coronary ligamentCoronary ligament• attaches menisci to the attaches menisci to the

tibiatibia

Synovial cavitySynovial cavity

Synovial cavitySynovial cavity• supplies knee with synovial fluid supplies knee with synovial fluid • lies under patella and between surfaces lies under patella and between surfaces

of tibia & femurof tibia & femur• "capsule of the knee”"capsule of the knee”

Fat PatFat Pat Infrapatellar fat padInfrapatellar fat pad

• just posterior to patellar tendonjust posterior to patellar tendon• an insertion point for synovial folds of an insertion point for synovial folds of

tissue known as “plica”tissue known as “plica”an anatomical variant that may be an anatomical variant that may be

irritated or inflamed with injuries or irritated or inflamed with injuries or overuse of the kneeoveruse of the knee

Anatomy ReviewAnatomy Review

Joint CapsuleJoint Capsule

BursaeBursae

BursaeBursae• more than 10 more than 10

bursae in & bursae in & around kneearound knee

• some are some are connected to connected to synovial cavitysynovial cavity

• they absorb they absorb shock or prevent shock or prevent frictionfriction

BursaeBursae Anteriorly:Anteriorly: Quadriceps Quadriceps

• between the quad and between the quad and femurfemur

Prepatellar Prepatellar • lies on top of the lies on top of the

patella (Housemaid’s patella (Housemaid’s knee)knee)

Deep infrapatella Deep infrapatella bursabursa• between the patella between the patella

tendon and tibiatendon and tibia Superfisical Superfisical

infrapatella bursainfrapatella bursa• between the patellar between the patellar

tendon and skintendon and skin

Anatomy ReviewAnatomy Review

Bursae Bursae

BursaeBursae Posteriorly:Posteriorly: Baker’s Cyst Baker’s Cyst

• lies between the lies between the semimembranosus semimembranosus tendon and the tendon and the medial head of the medial head of the gastroc muscle.gastroc muscle.

bursae also exist bursae also exist beneath the ITB beneath the ITB tendon and Pes tendon and Pes Anserine proximal Anserine proximal to their insertions.to their insertions.

JointsJoints

Extends to 180 degrees (0 Extends to 180 degrees (0 degrees of flexion)degrees of flexion)

Hyperextension of 10 degrees or Hyperextension of 10 degrees or > not uncommon> not uncommon

Flexion occurs to about 140 Flexion occurs to about 140 degreesdegrees

With knee flexed 30 degrees or >With knee flexed 30 degrees or >• internal rotation 30 degrees occursinternal rotation 30 degrees occurs• external rotation 45 degrees occurs external rotation 45 degrees occurs

MovementsMovements

FlexionFlexion• bending or decreasing bending or decreasing

angle between femur & angle between femur & leg, characterized by heel leg, characterized by heel moving toward buttocksmoving toward buttocks

ExtensionExtension• straightening or straightening or

increasing angle between increasing angle between femur & lower legfemur & lower leg

MovementsMovements

External rotationExternal rotation• rotary movement of leg rotary movement of leg

laterally away from midlinelaterally away from midline Internal rotationInternal rotation

• rotary movement of lower rotary movement of lower leg medially toward midlineleg medially toward midline

Neither will occur unless Neither will occur unless flexed 20-30 degrees or >flexed 20-30 degrees or >

BonesBones

Key bony landmarksKey bony landmarks• Superior & inferior patellar Superior & inferior patellar

polespoles• Tibial tuberosityTibial tuberosity• Gerdy’s tubercleGerdy’s tubercle• Medial & lateral Medial & lateral

femoralcondylesfemoralcondyles• adductor tubercleadductor tubercle• Upper anterior medial tibial Upper anterior medial tibial

surfacesurface• Head of fibulaHead of fibula

Soft tissue palpationSoft tissue palpation

infrapatella tendoinfrapatella tendo quad tendonquad tendon pes anserine insertionpes anserine insertion ITB insertionITB insertion medial and lateral medial and lateral

joint linejoint line gastroc headsgastroc heads medial and lateral medial and lateral

collateral ligaments collateral ligaments

prepatella bursaprepatella bursa infrapatella bursainfrapatella bursa fat padfat pad biceps femoris biceps femoris

tendontendon popliteal vein and popliteal vein and

artery(popliteal artery(popliteal fossa)fossa)

common peroneal common peroneal nervenerve

Knee Evaluation Knee Evaluation (Palpation)(Palpation)

Palpation - Soft Palpation - Soft TissueTissue• Vastus medialisVastus medialis• Vastus lateralisVastus lateralis• Vastus intermediusVastus intermedius• Rectus femorisRectus femoris• Quadriceps and patellar Quadriceps and patellar

tendontendon• SartoriusSartorius• Medial patellar plicaMedial patellar plica• Anterior joint capsuleAnterior joint capsule• Iliotibial BandIliotibial Band• Arcuate complexArcuate complex

Medial and lateral Medial and lateral collateral ligamentscollateral ligaments

Pes anserinePes anserine Medial/lateral joint capsuleMedial/lateral joint capsule SemitendinosusSemitendinosus SemimembranosusSemimembranosus GastrocnemiusGastrocnemius PopliteusPopliteus Biceps FemorisBiceps Femoris

Knee Evaluation Knee Evaluation (Palpation)(Palpation)

Palpation of SwellingPalpation of Swelling• Intra vs. extracapsular swellingIntra vs. extracapsular swelling• Intracapsular may be referred to as joint Intracapsular may be referred to as joint

effusioneffusion• Swelling w/in the joint that is caused by Swelling w/in the joint that is caused by

synovial fluid and blood is a hemarthrosissynovial fluid and blood is a hemarthrosis• Sweep maneuverSweep maneuver• Ballotable patella - sign of joint effusionBallotable patella - sign of joint effusion• Extracapsular swelling tends to localize over Extracapsular swelling tends to localize over

the injured structure the injured structure May ultimately migrate down to foot and ankleMay ultimately migrate down to foot and ankle

Special TestsSpecial Tests

- valgus stress test- valgus stress test - posterior drawer- posterior drawer - Appley distractio- Appley distractio - Nobles compression- Nobles compression - varus stress test- varus stress test - Godfrey’s test- Godfrey’s test - Slocum drawer- Slocum drawer - Wilson’s sign- Wilson’s sign

- Anterior drawer- Anterior drawer - McMurray’ test- McMurray’ test - Pivot shift- Pivot shift - Patellar Apphresion- Patellar Apphresion - lachman’s test- lachman’s test - Appley compression- Appley compression - Stutter test- Stutter test

COMMON INJURIES TO COMMON INJURIES TO THE KNEETHE KNEE

Quad contusion:Quad contusion:

etiology:etiology: • trauma to the quadtrauma to the quad

presentation:presentation:• possible ecchymosis possible ecchymosis • pain with knee extensionpain with knee extension• limited knee flexionlimited knee flexion• tenderness over quadtenderness over quad

Patellofemoral SyndromePatellofemoral Syndrome Etiology:Etiology: dysfunction of the extensor dysfunction of the extensor

mechanism caused by :mechanism caused by : patella alta, patella alta, lateral patellar tilt, lateral patellar tilt, Vmo dysplasia,Vmo dysplasia, Vastus lateralis hypertrophyVastus lateralis hypertrophy increased Q angleincreased Q angle squinting patellasquinting patella increased pain with prolonged sittingincreased pain with prolonged sitting increased pronation.increased pronation.

PresentationPresentation: :

anterior knee pain with descending anterior knee pain with descending stairs, stairs,

crepitus, crepitus, pain with squatting or sitting for pain with squatting or sitting for

prolonged periods, prolonged periods, tenderness along the medial patellar tenderness along the medial patellar

surface.surface.

Plica syndromePlica syndrome Etiology:Etiology:

• remains of embryologic synovial tissue remains of embryologic synovial tissue around the patella that become irritated around the patella that become irritated with trauma causing anterior knee pain.with trauma causing anterior knee pain.

Presentation:Presentation:

symptoms are similar to PFS, but symptoms are similar to PFS, but there is a palpable band on the there is a palpable band on the superior medial aspect of the patella superior medial aspect of the patella (most common) (most common)

Patellar TendonitisPatellar Tendonitis

Etiology:Etiology:

inflammation and or irritation of the inflammation and or irritation of the patellar tendon usually occurring in patellar tendon usually occurring in athletes who have excessive athletes who have excessive pounding through the knee pounding through the knee

Presentation:Presentation:

pain along the inferior pole of the pain along the inferior pole of the patella to palpation, patella to palpation,

pain with activity, jumping, stair pain with activity, jumping, stair climbingclimbing

tight quads/Hamstringstight quads/Hamstrings

LIGAMENTOUS LIGAMENTOUS INJURIES TO THE KNEEINJURIES TO THE KNEE

Anterior Cruciate LigamentAnterior Cruciate Ligament

prevents anterior displacement of prevents anterior displacement of the tibia on the femur and checks the tibia on the femur and checks internal rotation of the tibia on the internal rotation of the tibia on the femur.femur.

ACL is taught in all positions of knee ACL is taught in all positions of knee motion, with greatest tension in full motion, with greatest tension in full extensionextension

Etiology:Etiology:

hyperextension, internal rotation,hyperextension, internal rotation, hyperflexion by non-contact valgus hyperflexion by non-contact valgus

force with rotation can lead to ACL force with rotation can lead to ACL rupturerupture

PresentationPresentation

feeling of a "pop" inside of the knee feeling of a "pop" inside of the knee unstable feelingunstable feeling positive ACL tests positive ACL tests pain with movement.pain with movement. possibility of a hemarthrosispossibility of a hemarthrosis

Posterior Cruciate LigamentPosterior Cruciate Ligament

prevents posterior displacement of prevents posterior displacement of the tibia on the femurthe tibia on the femur

getting to be a more common injurygetting to be a more common injury

EEtiology:tiology:

posterior force on the tibia, posterior force on the tibia, hyperextension with a varus or hyperextension with a varus or

valgus stressvalgus stress

Presentation:Presentation:

positive PCL testspositive PCL tests unstable feeling with activityunstable feeling with activity possible hemarthrosispossible hemarthrosis pain with movementpain with movement

Medial and Lateral CollateralMedial and Lateral Collateral

prevent valgus(medial) and prevent valgus(medial) and varus(lateral) stress through the varus(lateral) stress through the knee.knee.

get taught with external rotation of get taught with external rotation of the tibia on the femur the tibia on the femur

EtiologyEtiology::

varus or valgus stress through the varus or valgus stress through the knee with the foot plantedknee with the foot planted

presentation:presentation:

positive varus test (LCL)positive varus test (LCL) positive valgus test (MCL)positive valgus test (MCL) unstable feeling with cuttingunstable feeling with cutting pain over adductor tuberclepain over adductor tubercle possible swellingpossible swelling

Meniscal InjuryMeniscal Injury

outer 1/3 of the meniscus is vascular outer 1/3 of the meniscus is vascular and can heal or be repairedand can heal or be repaired

act as shock absorbers, increase joint act as shock absorbers, increase joint congruency, aides to joint lubricationcongruency, aides to joint lubrication

etiologyetiology

traction or compression with rotation traction or compression with rotation and slight flexion of the kneeand slight flexion of the knee

PresentationPresentation

pain along the joint line pain along the joint line pain or clicking with McMurray'spain or clicking with McMurray's pain with squattingpain with squatting pain with stairspain with stairs pain with hamstring contractionpain with hamstring contraction