© 2007 McGraw-Hill Higher Education. All rights reserved. 10-1 Chapter 10 The Knee Joint Manual of Structural Kinesiology R.T. Floyd, EdD, ATC, CSCS

© 2007 McGraw-Hill Higher Education. All rights © 2007 McGraw-Hill Higher Education. All rights reserved. reserved. 10-10-11

Chapter 10Chapter 10The Knee JointThe Knee Joint

Manual of Structural KinesiologyManual of Structural KinesiologyR.T. Floyd, EdD, ATC, CSCSR.T. Floyd, EdD, ATC, CSCS


The Knee JointThe Knee Joint

• Knee jointKnee joint– largest joint in largest joint in

bodybody– very complexvery complex– primarily a primarily a

hinge jointhinge jointModified for Prentice WE: Arnheim’s principles of athletic training, ed 12, New York, 2006, McGraw-Hill; from Saladin, KS: Anatomy &physiology: the unity of forms and function, ed 2, New York, 2001, McGraw-Hill.


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

Modified from Anthony CP, Kolthoff NJ: Textbook of anatomy and physiology, ed 9, St. Louis, 1975, Mosby.


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


BonesBones

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

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

condylescondyles– Upper anterior medial tibial Upper anterior medial tibial

surfacesurface– Head of fibulaHead of fibula



BonesBones

• Three vasti muscles of quadriceps Three vasti muscles of quadriceps originate on proximal femur & insert on originate on proximal femur & insert on patellar superior polepatellar superior pole– insertion is ultimately on tibial tuberosity insertion is ultimately on tibial tuberosity

via patella tendonvia patella tendon

• Iliotibial tract of tensor fasciae latae Iliotibial tract of tensor fasciae latae inserts on Gerdy’s tubercleinserts on Gerdy’s tubercle

• Sartorius, gracilis, & semitendinosus Sartorius, gracilis, & semitendinosus insert just below the medial condyle on insert just below the medial condyle on upper anteromedial tibial surfaceupper anteromedial tibial surface


BonesBones

• Semimembranosus inserts posteromedially Semimembranosus inserts posteromedially on medial tibial condyleon medial tibial condyle

• Biceps femoris inserts primarily on fibula Biceps femoris inserts primarily on fibula headhead

• Popliteus originates on lateral aspect of Popliteus originates on lateral aspect of lateral femoral condylelateral femoral condyle

• Tibial collateral ligament originates on Tibial collateral ligament originates on medial aspect of upper medial femoral medial aspect of upper medial femoral condyle & inserts on medial tibial surfacecondyle & inserts on medial tibial surface

• Fibula collateral originates on lateral femoral Fibula collateral originates on lateral femoral condyle very close to popliteus origin & condyle very close to popliteus origin & inserts on fibular headinserts on fibular head


JointsJoints

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

• Sometimes referred to as Sometimes referred to as trochoginglymus joint internal & external trochoginglymus joint internal & external rotation occur during flexionrotation occur during 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

© 2007 McGraw-Hill Higher Education. All rights © 2007 McGraw-Hill Higher Education. All rights reserved. reserved.

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JointsJoints

• Ligaments provide static stabilityLigaments provide static stability• Quadriceps & hamstrings contractions Quadriceps & hamstrings contractions

produce dynamic stabilityproduce dynamic stability• Articular cartilage surfaces on femur & tibiaArticular cartilage surfaces on femur & tibia• Menisci form cushions between bonesMenisci form cushions between bones

– attached to tibia attached to tibia – deepen tibial fossadeepen tibial fossa– enhance stabilityenhance stability



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JointsJoints

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

very thin to inside bordervery thin 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


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JointsJoints

– Either or both menisci may be Either or both menisci may be torn in several different areas torn in several different areas from a variety of mechanisms, from a variety of mechanisms, resulting in varying degrees of resulting in varying degrees of problemsproblems•Tears 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


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JointsJoints

• 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


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JointsJoints

• Posterior cruciate Posterior cruciate ligament (PCL) injuriesligament (PCL) injuries– not often injurednot often injured– mechanism of direct mechanism of direct

contact with an contact with an opponent or playing opponent or playing surfacesurface

• Fibular (lateral) Fibular (lateral) collateral ligament collateral ligament (LCL)(LCL)– infrequently injuredinfrequently injured



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JointsJoints

• Tibial (medial) collateral ligament (MCL)Tibial (medial) collateral ligament (MCL)– maintains medial stability by resisting maintains medial stability by resisting

valgus forces or preventing knee from valgus forces or preventing knee from being abductedbeing abducted

– 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


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JointsJoints

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

tibia & femurtibia & femur– "capsule of the knee”"capsule of the knee”

• Infrapatellar fat padInfrapatellar fat pad– just posterior to patellar tendonjust posterior to patellar tendon– an insertion point for synovial folds of tissue an insertion point for synovial folds of tissue

known as “plica”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


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JointsJoints

• 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 shock or prevent frictionprevent friction


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JointsJoints

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

• Hyperextension of 10 degrees Hyperextension of 10 degrees or > not uncommonor > 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 external rotation 45 degrees

occurs occurs


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JointsJoints

• 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 knee “unlocks” by tibia rotating internally, to

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


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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


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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 >


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MusclesMuscles• Quadriceps muscle Quadriceps muscle

groupgroup– extends kneeextends knee– located in anterior located in anterior

compartment of thighcompartment of thigh– consists of 4 musclesconsists of 4 muscles

• rectus femorisrectus femoris• vastus lateralisvastus lateralis• vastus intermediusvastus intermedius• vastus medialisvastus medialis


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MusclesMuscles• Q angleQ angle

– Central line of pull for entire Central line of pull for entire quadriceps runs from ASIS to the quadriceps runs from ASIS to the center of patellacenter of patella

– Line of pull of patella tendon runs Line of pull of patella tendon runs from center of patella to center of from center of patella to center of tibial tuberositytibial tuberosity

– Angle formed by the intersection of Angle formed by the intersection of these two lines at the patella is the these two lines at the patella is the Q angleQ angle

– Normally, angle will be 15 degrees Normally, angle will be 15 degrees or less for males & 20 degrees or or less for males & 20 degrees or less in femalesless in females

– Generally, females have higher Generally, females have higher angles due to a wider pelvisangles due to a wider pelvis


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MusclesMuscles• Q angleQ angle

– Higher Q angles generally Higher Q angles generally predispose people in varying predispose people in varying degrees to a variety of potential degrees to a variety of potential knee problems including lateral knee problems including lateral patellar subluxation or dislocation, patellar subluxation or dislocation, patellar compression syndrome, patellar compression syndrome, chondromalacia, and ligamentous chondromalacia, and ligamentous injuriesinjuries

– For people with above normal Q For people with above normal Q angles, it is particularly important angles, it is particularly important to maintain high levels of strength to maintain high levels of strength & endurance in vastus medialis so & endurance in vastus medialis so as to counteract lateral pull of as to counteract lateral pull of vastus lateralisvastus lateralis


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MusclesMuscles• Hamstring muscle groupHamstring muscle group

– responsible for knee flexionresponsible for knee flexion– located in posterior compartment of located in posterior compartment of

thighthigh– consists of 3 musclesconsists of 3 muscles

• semitendinosus - medial, internal rotatorsemitendinosus - medial, internal rotator• semimembranosus - medial, internal rotatorsemimembranosus - medial, internal rotator• biceps femoris - lateral, external rotatorbiceps femoris - lateral, external rotator

• Popliteus assist medial hamstrings in Popliteus assist medial hamstrings in knee internal rotationknee internal rotation


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MusclesMuscles• Two-joint musclesTwo-joint muscles

– most effective when either origin or most effective when either origin or insertion is stabilized to prevent insertion is stabilized to prevent movement in direction of the movement in direction of the contacting musclecontacting muscle

– To a degree, muscles are able to To a degree, muscles are able to exert greater force when lengthened exert greater force when lengthened than when shortenedthan when shortened

– Hamstring muscles & rectus femoris Hamstring muscles & rectus femoris are biarticular (two-joint) musclesare biarticular (two-joint) muscles


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MusclesMuscles• Ex. sartorius muscleEx. sartorius muscle

– increases its total length & becomes a increases its total length & becomes a better flexor at knee when pelvis is better flexor at knee when pelvis is rotated posteriorly & stabilized by rotated posteriorly & stabilized by abdominal musclesabdominal muscles• exemplified by trying to flex knee & cross the exemplified by trying to flex knee & cross the

legs in the sitting positionlegs in the sitting position• one usually leans backward to flex legs at one usually leans backward to flex legs at

kneesknees

– Football kicker invariably leans well Football kicker invariably leans well backward to raise & fix the rectus femoris backward to raise & fix the rectus femoris origin to make it more effective as a knee origin to make it more effective as a knee extensorextensor


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MusclesMuscles

• Gracilis, sartorius, & semitendinosus join Gracilis, sartorius, & semitendinosus join together distally to form pes anserinustogether distally to form pes anserinus– attaches to anteromedial aspect of proximal attaches to anteromedial aspect of proximal

tibia below the level of tibial tuberositytibia below the level of tibial tuberosity– Their attachment & posteromedially line of Their attachment & posteromedially line of

pull enable them to assist with knee flexion pull enable them to assist with knee flexion particularly once the knee is flexed & hip is particularly once the knee is flexed & hip is externally rotatedexternally rotated

• Medial & lateral gastrocnemius heads Medial & lateral gastrocnemius heads attach posteriorly on medial & lateral attach posteriorly on medial & lateral femoral condylesfemoral condyles– assist with knee flexion assist with knee flexion


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MusclesMuscles

Knee joint muscles Knee joint muscles locationlocation

• Anterior - primarily Anterior - primarily knee extensionknee extension– Rectus femorisRectus femoris– Vastus medialisVastus medialis– Vastus intermediusVastus intermedius– Vastus lateralisVastus lateralis


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MusclesMuscles

Knee joint muscles locationKnee joint muscles location• Posterior - primarily knee flexionPosterior - primarily knee flexion

– Biceps femorisBiceps femoris– SemimembranosusSemimembranosus– SemitendinosusSemitendinosus

• SartoriusSartorius• GracilisGracilis• PopliteusPopliteus• Gastrocnemius Gastrocnemius


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NervesNerves• Femoral nerves Femoral nerves

innervates the knee innervates the knee extensors extensors (quadriceps)(quadriceps)– rectus femorisrectus femoris– vastus medialisvastus medialis– vastus intermediusvastus intermedius– vastus lateralis vastus lateralis


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NervesNerves• Sciatic nerveSciatic nerve

– tibial divisiontibial division• semitendinosus, semitendinosus,

semimembranosus, semimembranosus, biceps femoris (long biceps femoris (long head) head)

– common peroneal common peroneal (fibular) division(fibular) division• biceps femoris (short biceps femoris (short

head)head)


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Quadriceps Quadriceps MusclesMuscles

• Quadriceps muscles - vital in Quadriceps muscles - vital in jumpingjumping– functions as a deceleratorfunctions as a decelerator

• when decreasing speed to change when decreasing speed to change directiondirection

• when coming down from a jumpwhen coming down from a jump

– eccentric contraction during eccentric contraction during decelerating actionsdecelerating actions

– controls slowing of movements controls slowing of movements initiated in previous phases of the initiated in previous phases of the sports skillsports skill


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• Rectus femoris (two-joint), vastus Rectus femoris (two-joint), vastus medialis, vastus intermedius, vastus medialis, vastus intermedius, vastus lateralis (largest)lateralis (largest)• All attach to patella then to tibial tuberosity All attach to patella then to tibial tuberosity

via patellar tendonvia patellar tendon• All superficial & palpable except vastus All superficial & palpable except vastus

intermedius (under rectus femoris)intermedius (under rectus femoris)• Strength or power may be indicated by Strength or power may be indicated by

vertical jump testvertical jump test• Generally desired to be 25% to 33% stronger Generally desired to be 25% to 33% stronger

than hamstring groupthan hamstring group


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• Strength & endurance is essential for Strength & endurance is essential for maintenance of patellofemoral stabilitymaintenance of patellofemoral stability– often a problemoften a problem– quads are particularly prone to atrophy quads are particularly prone to atrophy

when injuries occurwhen injuries occur– may be developed by resisted knee may be developed by resisted knee

extension activities from a seated positionextension activities from a seated position– functional weight bearing activities such functional weight bearing activities such

as step-ups or squats are particularly as step-ups or squats are particularly useful for strengthening & enduranceuseful for strengthening & endurance


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Rectus Femoris Rectus Femoris MuscleMuscle

Flexion of hipFlexion of hip

Extension of Extension of kneeknee

Anterior pelvic Anterior pelvic rotationrotation


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Vastus Lateralis Vastus Lateralis MuscleMuscle



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Vastus Intermedius Vastus Intermedius MuscleMuscle



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Vastus Medialis Vastus Medialis MuscleMuscle



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Hamstring Hamstring MusclesMuscles

• Hamstring muscle groupHamstring muscle group– SemitendinosusSemitendinosus– Biceps femorisBiceps femoris– SemimembranosusSemimembranosus


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Hamstring Hamstring MusclesMuscles

• Hamstring muscle strains very commonHamstring muscle strains very common• ““Running muscles” function in accelerationRunning muscles” function in acceleration• Antagonists to quadriceps muscles at kneeAntagonists to quadriceps muscles at knee• Named for cordlike attachments at kneeNamed for cordlike attachments at knee• All originate on ischial tuberosity of pelvisAll originate on ischial tuberosity of pelvis• Semitendinosus inserts on anteromedial tibiaSemitendinosus inserts on anteromedial tibia• Semimembranosus inserts on posteromedial Semimembranosus inserts on posteromedial

tibiatibia• Biceps femoris inserts on lateral tibial condyle Biceps femoris inserts on lateral tibial condyle

& head of fibula& head of fibula


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Semitendinosus Semitendinosus MuscleMuscle Flexion of kneeFlexion of knee

Extension of hipExtension of hip

Internal Internal rotation of rotation of hiphip

Internal Internal rotation of rotation of flexed knee flexed knee

Posterior pelvic Posterior pelvic rotationrotation


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Semimembranosus Semimembranosus MuscleMuscle Flexion of kneeFlexion of knee

Extension of hipExtension of hip

Internal rotation Internal rotation of hipof hip

Internal rotation Internal rotation of flexed of flexed knee knee



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Biceps Femoris MuscleBiceps Femoris Muscle Flexion of kneeFlexion of knee

Extension Extension of hipof hip

External External rotation rotation of hipof hip

External External rotation rotation of flexed of flexed knee knee



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Popliteus MusclePopliteus Muscle Flexion of kneeFlexion of knee

Internal Internal rotation of rotation of flexed knee flexed knee


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Knee ExtensionKnee Extension

• AgonistsAgonists– Rectus FemorisRectus Femoris– Vastus LateralisVastus Lateralis– Vastus IntermediusVastus Intermedius– Vastus MedialisVastus Medialis


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Knee FlexionKnee Flexion• AgonistsAgonists

– Biceps Femoris Biceps Femoris (Long & Short (Long & Short Head)Head)

– SemitendinosusSemitendinosus– SemimembranosusSemimembranosus


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Knee Internal RotationKnee Internal Rotation

• AgonistsAgonists– SemitendinosusSemitendinosus– SemimembranosusSemimembranosus– PopliteusPopliteus


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Knee External RotationKnee External Rotation

• AgonistsAgonists– Biceps FemorisBiceps Femoris


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Web SitesWeb SitesRadiologic Anatomy Browser

http://radlinux1.usuf1.usuhs.mil/rad/iong – This site has numerous radiological views of the musculoskeletal

system.University of Arkansas Medical School Gross Anatomy for Medical

Studentshttp://anatomy.uams.edu/anatomyhtml/gross.html – Dissections, anatomy tables, atlas images, links, etc.

Loyola University Medical Center: Structure of the Human Bodywww.meddean.luc.edu/lumen/meded/grossanatomy/index.htm – An excellent site with many slides, dissections, tutorials, etc. for the

study of human anatomyWheeless’ Textbook of Orthopaedics

www.wheelessonline.com/– This site has an extensive index of links to the fractures, joints,

muscles, nerves, trauma, medications, medical topics, lab tests, and links to orthopedic journals and other orthopedic and medical news.


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Web SitesWeb SitesPremiere Medical Search Engine

www.medsite.com – This site allows the reader to enter any medical condition and it will

search the net to find relevant articles.Arthroscopy.com

www.arthroscopy.com/sports.htm– Patient information on various musculoskeletal problems of the lower

extremityVirtual Hospital

www.vh.org – Numerous slides, patient information, etc.

Human Anatomy Onlinewww.innerbody.com/image/musc08.html– Interactive musculoskeletal anatomy

The Hip and Knee Institutewww.hipsandknees.com/knee/index.html– Arthritis of the Knee Joint


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Web SitesWeb SitesAdam Healthcare Center

http://adam.about.com/surgery/100088.htm#– Knee joint replacement

American Academy of Orthopaedic Surgeonshttp://orthoinfo.aaos.org/category.cfm?topcategory=Knee– Patient education library on the knee

Edheads Activitieswww.edheads.org/activities/knee/– Allows you to perform virtual knee surgery

Gross Anatomy: The Functional Anatomy of the Knee Jointwww.upstate.edu/cdb/grossanat/limbs8.shtml– Functional Anatomy of the Knee

Knee Ligament Anatomy and Injurywww.orthoassociates.com/knee_lig.htm– Anatomy and injuries of the Knee and its ligaments


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Web SitesWeb SitesDuke Orthopaedics

www.wheelessonline.com/ortho/anatomy_and_kinematics_of_the_knee_joint

– Anatomy and Kinematics of the knee jointKnee Injury: Meniscus

www.patient.co.uk/showdoc/27000672/– Understanding the knee joint and purpose of meniscus

Smart Play: The Kneewww.smartplay.net/ouch/bodybits/b_bitsknee.html– Anatomy, functions, injuries, etc. of the knee

Patellofemoral Instabilitywww.massgeneral.org/ortho/PatellofemoralInstability.htm– Patella Femoral Alignment

Chiroweb.comwww.chiroweb.com/archives/21/24/03.html – Abnormal Q Angle and Orthotic Support


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Web SitesWeb SitesThe Physician and Sportsmedicine

www.physsportsmed.com/issues/1997/05may/bach.htm– Acute Knee Injuries: When to Refer

The Physician and Sportsmedicinewww.physsportsmed.com/issues/1999/10_01_99/laprade.htm– Acute Knee Injuries: On-the-Field and Sideline Evaluation

Documents

© 2007 McGraw-Hill Higher Education. All rights reserved. 10-1 Chapter 10 The Knee Joint Manual of Structural Kinesiology R.T. Floyd, EdD, ATC, CSCS