Manual of Structural Kinesiology The Knee Joint 10-1 Chapter 10 The Knee Joint Manual of Structural...

Manual of Manual of Structural Structural KinesiologyKinesiology The Knee JointThe Knee Joint 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 largest joint in bodyin body

– very complexvery complex– primarily a primarily a hinge jointhinge joint


BonesBones

• Enlarged femoral condyles Enlarged femoral condyles articulate on enlarged tibial articulate on enlarged tibial condylescondyles

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

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


BonesBones

• Fibula - Fibula - laterallateral– 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 femur or patellapatella

– not part of not part of knee jointknee joint


BonesBones

• PatellaPatella– sesamoid (floating) sesamoid (floating) bonebone

– imbedded in quadriceps imbedded in quadriceps & patellar tendon& patellar tendon

– serves similar to a serves similar to a pulley in improving pulley in improving angle of pull, angle of pull, resulting in greater resulting in greater mechanical advantage mechanical advantage in knee extensionin knee extension


BonesBones

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

– Tibial tuberosityTibial tuberosity– GerdyGerdy’’s tubercles tubercle– Medial & lateral femoral Medial & lateral femoral condylescondyles

– Upper anterior medial Upper anterior medial tibial surfacetibial surface

– Head of fibulaHead of fibula


JointsJoints

• Ligaments provide static stabilityLigaments provide static stability• Quadriceps & hamstrings contractions Quadriceps & hamstrings contractions produce dynamic stabilityproduce dynamic stability

• Articular cartilage surfaces Articular cartilage surfaces on femur & tibiaon femur & tibia

• Menisci form cushions Menisci form cushions between bonesbetween bones– attached to tibia attached to tibia – deepen tibial fossadeepen tibial fossa– enhance stabilityenhance stability


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 rotation while flexing or extending during quick extending during quick directional changes in runningdirectional changes in running


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 posterior stability, as well as rotatory stabilitystability

• Anterior cruciate ligament (ACL) Anterior cruciate ligament (ACL) injuriesinjuries– 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 contraction which pulls tibia forward on femur femur

Manual of Manual of Structural Structural KinesiologyKinesiology The Knee JointThe Knee Joint

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JointsJoints

• 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 surfacesurface

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


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JointsJoints

• Tibial (medial) collateral ligament Tibial (medial) collateral ligament (MCL)(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 fall against lateral aspect of knee or leg causing medial opening of knee joint leg causing medial opening of knee joint & stress to medial ligamentous & stress to medial ligamentous structuresstructures


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JointsJoints

• Synovial cavitySynovial cavity– supplies knee with synovial fluid supplies knee with synovial fluid – lies under patella and between lies under patella and between surfaces of tibia & femursurfaces of tibia & 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 an insertion point for synovial folds of tissue known as of tissue known as ““plicaplica””• an anatomical variant that may be an anatomical variant that may be irritated or inflamed with injuries irritated or inflamed with injuries or overuse of the kneeor overuse 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 synovial cavitycavity

– they absorb they absorb shock or shock or prevent prevent frictionfriction


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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 With knee flexed 30 degrees or >or >– internal rotation 30 degrees internal rotation 30 degrees occursoccurs

– external rotation 45 degrees external rotation 45 degrees occurs occurs


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JointsJoints

• Knee Knee ““screws homescrews home”” to fully extend due to fully extend due to the shape of medial femoral condyleto the shape of medial femoral condyle– As knee approaches full extension tibia As knee approaches full extension tibia must externally rotate approximately 10 must externally rotate approximately 10 degrees to achieve proper alignment of degrees to achieve proper alignment of tibial & femoral condylestibial & femoral condyles

– 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 knee ““unlocksunlocks”” by tibia rotating by tibia rotating internally, to a degree, from its internally, to a degree, from its externally rotated position to achieve externally rotated position to achieve flexion 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• 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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