KNEE BIOMECHANIC
SDr. Pukhrambam Ratan khuman (PT)
M.P.T., (Ortho & Sports)
April 11, 2023 Dr. Ratankhuman M.P.T., (Ortho & Sports) 2
introduction
Participating bones –FemurTibiaPatella
April 11, 2023 Dr. Ratankhuman M.P.T., (Ortho & Sports) 3
Knee complex
Tibio-femoral joint Patello-femoral joint
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Tibio-femoral/Knee joint Ginglymus – (Hinge) ?
A freely moving joint in which the bones are so articulated as to allow extensive movement in one plane.
Arthodial – (Gliding) ? 6 degrees of freedom
3 Rotations3 Translations
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Knee degree of freedom
RotationsFlex/Ext – 150 – 1400
Varus/Valgus – 60 – 80 in extensionInt/ext rotation – 250 – 300 in flexion
TranslationsAP 5 - 10mmCompression/Distraction 2 - 5mmMedial/Lateral 1-2mm
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General Features of Tibio-femoral Joint Double condyloid knee joint is also referred to as Medial
& Lateral Compartments of the knee. Double condyloid joint with 30 freedom of Angular
(Rotatory) motion. Flexion/Extension – ○ Plane – Sagittal plane○ Axis – Coronal axis
Medial/lateral (int/ext) rotation –○ Plane – Transverse plane ○ Axis – Longitudinal axis
Abduction/Adduction – ○ Plane – Frontal plane ○ Axis – Antero-posterior axis.
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Femoral articular surface
Femur is proximal articular surface of the knee joint with large medial & lateral condyles.
Because of obliquity of shaft, the femoral condyles do not lie immediately below the femoral head but are slightly medial to it.
The medial condyle extend further distally, so that, despite the angulation of the femur’s shaft, the distal end of the femur remains essentially horizontal.
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In sagittal plane - Condyles have a convex shape In the frontal plane - Slight convexity The lateral femoral condyle
Shifted anteriorly in relation to medialArticular surface is shorter Inferiorly, the lateral condyle appears to be longer
Two condyles are separated –Inferiorly by Intercondylar notch Anteriorly by an asymmetrical, shallow groove called
the Patellar Groove or Surface
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Tibial articulating surface Asymmetrical medial & lateral tibial condyles
constitute the distal articular surface of knee joint. Medial tibial plateau is longer in AP direction than
lateral The lateral tibial articular cartilage is thicker than
the medial side. Tibial plateau slopes posteriorly approx 70 to 100
Medial & lateral tibial condyles are separated by two bony spines called the Intercondylar Tubercles
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9o
The tibial plateaus are predominantly flat, but convexity at anterior & posterior margins
Because of this lack of bony stability, accessory joint structures (menisci) are necessary to improve joint congruency.
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Menisci of knee joint 2 asymmetrical fibro cartilaginous joint disk
called Menisci are located on tibial plateau. The medial meniscus is a semicircle & the
lateral is 4/5 of a ring (Williams, PL, 1995).
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Both menisci are –Open towards intercondylar
areaThick peripherallyThin centrally forming
cavities for femoral condyle By increasing congruence,
menisci play in reducing friction between the joint segment & serve as shock absorber.
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Meniscal attachment Common attachment of medial & lateral –
Intercondylar tubercles of the tibiaTibial condyle via coronary ligamentsPatella via patellomeniscal or patellofemoral ligamentTransverse ligament between two menisciAnterior cruciate ligament (ACL)
April 11, 2023 Dr. Ratankhuman M.P.T., (Ortho & Sports) 16
Meniscal attachment Unique attachment of medial menisci –
Medial collateral ligament (MCL)Semitendinous muscle
Unique attachment of lateral menisci –Anterior & posterior meniscofemoral ligamentPosterior cruciate ligament (PCL)Popliteus muscle
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Young children whose menisci have ample of blood supply have low incidence of injury
In adult, only the peripheral vascularized region is capable of inflammation, repair & remodeling following a tearing injury.
Menisci are well innervated with free nerve ending & 3 mechanoreceptors (Ruffine corpuscle, Pacinian corpuscle & Golgi tendon organs)
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TF alignment & weight bearing force The anatomic/ longitudinal axis –
Femur – Oblique, directed inferiorly & mediallyTibia – Directed verticallyThe femoral & tibial longitudinal axis form an angle
medially at the knee joint of 1850 – 1900, i.e. 50 – 100 creating Physiological Valgus at knee
In bilateral static stance – equal weight distribution on medial & lateral condyle
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Deviation in normal force distribution – TF angle > 1900 – Genu Valgum – compress
lateral condyleTF angle < 1800 – Genu Varum – compress
medial condyle Compressive force in dynamic knee joint
2 – 3 time body weight in normal gait5 – 6 time body weight in activities (like –
Running, Stair Climbing etc.)
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Knee joint capsule Joint capsule enclose – TF & PF is large lax Outer portion – firmly attached to the inferior aspect
of femur & superior portion of tibia. Posterior attachment
Proximally to posterior margins of the femoral condyles and intercondylar notch.
Distally to posterior tibial condyle. Anterior attachment
Superiorly – Patella, tendon of quadriceps muscles Inferiorly patellar tendon complete the anterior portion
of the joint capsule.
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The antero-medial & antero-lateral portions of the capsule, are often separately identified as the medial and lateral patellar retinaculae or together as the extensor retinaculum.
The joint capsule is reinforced medially, laterally & posteriorly by capsular ligaments.
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Extensor retinaculum
2 layers – superficial & deeper Deeper layer –
Connecting the capsule anteriorly to menisci & tibia via coronary ligament (known as patellomeniscal or patellotibial band)
Superficial layer – Mixed with vastus medialis & lateralis muscle &
distal continue to posterior femoral condyle (patellofemoral ligament)
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Synovial lining The intricacy of fibrous layer
capsule is surpassed by its synovial lining except posteriorly.
Synovium adheres to anterior aspect & side to the ACL & PCL.
Embryologically, the synovial lining of the knee joint capsule is divided by septa into 3 separate compartment – Superior patellofemoral compartment2 separate medial & lateral
tibiofemoral compartment
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Ligament of knee joint Collateral ligament
Medial collateral ligament (MCL)Lateral collateral ligament (LCL)
Cruciate ligamentAnterior cruciate ligament (ACL)Posterior cruciate ligament (PCL)
Posterior capsular ligament Meniscofemoral ligament Iliotibial band
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MCL
Attachment – Origin – medial aspect of medial femoral
condyleInsertion – proximal tibia
Function –Resist valgus stress force (specially in
extended knee)Check lateral rotation of tibiaAlso restrain anterior displacement of tibia
when ACL is absent.
MCL
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LCL Attachment –
Origin – lateral femoral condyleInsertion – posteriorly to head
of fibula Function –
Resist varus stress force across the knee
Check combined lateral rotation with posterior displacement of tibia in conjunction with tendon of popliteal muscle.
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Cruciate ligament
Cruciate = “Resembling a cross” in Latin.
Located within the joint capsule & are therefore called Intracapsular Ligaments.
Cruciate ligament provide stability in sagittal plane
The ACL & PCL are centrally located within the capsule but lie outside the synovial cavity.
ACLPCL
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ACL
Attachment –Origin – from anterior surface the tibia in the
intercondylar area just medial to medial meniscus. It spans the knee laterally to PCL & runs in a superior
& posterior direction Insertion – to posteriorly on lateral condyle of femur
ACL is divided into 2 bands – Antero-medial band (AMB)Postero-lateral band (PLB)
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Function of acl Primarily –
Check femur from being displaced posteriorly on the tibia Conversely, the tibia from being displaced anteriorly on
femur. It tightens during extension, preventing excessive
hyperextension of the knee. ACL carried 87% of load when anterior translatory
force was applied to tibia with extended knee. Check tibial medial rotation by twisting around PCL ACL injury is common when knee is in flexed & tibia
rotated in either direction
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PCL
Attachment – Origin – from posterior tibia in intercondylar area
and runs in a superior and anterior direction on medial side of ACL.
Insertion - to anterior femur on the medial condyle PCL is divided into 2 bands –
Antero-medial band (AMB)Postero-lateral band (PLB)
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Function of pcl Primarily –
Check femur from being displaced anteriorly on the tibia or
Tibia from being displaced posteriorly on femur. It tightens during flexion & is injured much less
frequently than ACL. PCL carry 93% of load when posterior translatory
force was applied to tibia with extended knee. PCL play a role in both restraining & producing
rotation of the tibia.
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Summary of ACL & PCL attachments –ACL – Runs from anterior tibia to posterior femur PCL – Runs from posterior tibia to anterior femur
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Posterior capsular ligament
Oblique popliteal ligament Posterior oblique ligament Arcuate ligament:
Arcuate ligament lateral branchArcuate ligament medial branch
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Oblique popliteal ligament
Attachment –Origin – The central part of posterior aspect of
the joint capsuleInsertion - Posterior medial tibial condyle
Function –Reinforces posteromedial knee joint capsule
obliquely on a lateral-to-medial diagonal from proximal to distal
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Posterior oblique ligament
Attachment – Origin – Near the proximal origin of the MCL
and adductor tubercleInsertion – Posteromedial tibia, posterior capsule
& posteromedial aspect of the medial meniscus Function –
Reinforces the posteromedial knee joint capsule obliquely on a medial-to-lateral diagonal from proximal to distal
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Arcuate LigamentLateral Branch Medial branch
Distal Attachment
From posterior aspect of the head of the fibula
Proximal Attachment
To tendon of popliteus muscle & posterior capsule
Into oblique popliteal lig on medial side of joint
FunctionReinforces the postero-lateral knee joint capsule
obliquely on a medial to lateral from proximal to distal
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Meniscofemoral ligament (MFl)
There are 2 portions of MFL, at least one in 91% of knees & 30% knee having both.
MFL are not true ligaments because they attach bone to meniscus, rather than bone to bone.
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Meniscofemoral ligament (MFl) Attachment –
Origin – Both originate from posterior horn of lateral meniscus
Insertion – to lateral aspect of medial femoral condyle ○ The “Ligament of Humphry” or “Antero-MFL” is the
ligament run anterior to PCL on tibia ○ The “Ligament of Wrisberg” or “Postero-MFL” is the
ligament run posterior to PCL, also known as “3rd Cruciate Ligament of Robert”
Function – They may assist PCL in restraining posterior tibial translationAlso assist popliteus muscle by checking tibial lateral rotation
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Bursa associated with knee
Pre-patellar bursa – Located between the skin & anterior surface of patella They allows free movement of skin over patella during
knee flexion & extension Subcutaneous bursa –
Located between patellar ligament & overlying skin Deep infra-patellar bursa –
Located between patellar ligament & tibial tuberosityHelps in reducing friction between the patellar ligament
& tibial tuberosity
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Function of knee joint
Osteokinemetic of knee joint – Primary motions – ○ Flexion / Extension○ Medial / Lateral Rotation
Secondary motions – ○ Antero-posterior displacement of femur or tibia○ Abduction / Adduction through valgus or varus force
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Flexion & extension
Axis – no fixed axis but move through ROM (frontal axis)
Plan – sagittal plan ROM of flexion / extension –
Flexion – 1300 – 1400
Extension – 50 – 100 (Consider normal, beyond this termed as Genurecurvatum)
In close kinematic chain (OKC) – flexion / extension range is limited by ankle range.
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Medial / lateral rotation
Axis – Longitudinal / Vertical axis Plan – Transvers plan ROM at 900 knee flexion –
Lateral rotation – 00 – 400
Medial rotation – 00 – 300
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TF CKC Flexion
Early 00 - 250 knee flexion –Posterior rolling of femoral
condyles on the tibia As flexion continues –
Posterior Rolling accompanied by simultaneous Anterior glide of femur
Create a pure Spin of femur on the posterior tibia
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TF CKC extension
Extension from flexion is a reversal of flexion motion.
Early extension –Anterior rolling of femoral
condyles on tibial plateau As extension continues –
Anterior Rolling accompanied by simultaneous Posterior glide of femur
Produce a pure Spin of femoral condyles on tibial plateau
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Tf ock flexion / extension
When tibia is flexed on a fixed femur –The tibia performed Both Posterior Rolling &
Gliding on relatively fixed femoral condyles.
When tibia is Extended on a fixed femur –The tibia performed Both Anterior Rolling &
Gliding on relatively fixed femoral condyles.
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Locking & unlocking (screw home mechanism)
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Locking of knee joint CKC femoral extension from 300 flexion –
Larger medial femoral condyle continue rolling & gliding posteriorly when smaller lateral side stopped.
These result in medial rotation of femur on tibia, seen in last 50 of extension.
The medial rotation of femur at final stage of extension is not voluntary or produce by muscular force, which is referred as “Automatic” or “Terminal Rotation”.
The rotation within the joint bring the joint into a closed packed or Locked position.
The consequences of automatic rotation is also known as “Locking Mechanism” or “Screw Home Mechanism”.
OKC – lateral rotation of tibia on fixed femur
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Unlocking of knee joint
To initiate flexion, knee must be unlocked. A flexion force will automatically result in lateral
rotation of femur Because the larger medial condyle will move before
the shorter lateral condyle.Popliteus is the primary muscle to unlocked the knee.
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Role of Cruciate Ligaments
in Flexion/Extension
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TF CKC Flexion: ACL Control
At full extension –Angle of ACL
inclination greatestAnterior directed
component force will eventually Restrain Posterior Femoral Roll
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TF CKC Flexion: ACL Control cont…
As TF flexion increases – Angle of ACL inclination
decreasesAnterior directed
component force increases sufficient enough to produce Anterior Femoral Slide
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Hyperextension Impact on ACL
End ROM extension brings the mid-substance of the ACL in contact with the femoral intercondylar shelf (notch of Grant)
This contact point acts as a fulcrum to tension load the ACL
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TF CKC Flexion: PCL Control
Angle Of PCL Inclination is greatest at full flexion.
Anterior directed component force will eventually Restrain Posterior Femoral Roll
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TF CKC Extension: PCL Control
As TF extension increases –Angle Of PCL Inclination
decreasesPosterior directed component
force increases sufficient enough to Produce Posterior Femoral Slide
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TF OKC Extension Arthrokinematics sagittal plan
Extension – Meniscal migrate Anteriorly – ○ Because of meniso-patellar
ligament
Menisco-patellar Ligaments
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TF OKC flexion Arthrokinematics sagittal plan
Flexion – Menisci migrate posteriorly because of Semimembranosis attachment to medial meniscusPopliteus attachment to lateral meniscus
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Knee axial rotation
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Axial rotation of kneearthrokinemetic Axis – vertical axis Plan – transvers plan ROM – Maximum range is
available at 90 of knee flexion. The magnitude rotation diminishes
as the knee approaches both full extension and full flexion.
Medial condyle acts as pivot point while the lateral condyles move through a greater arc of motion, regardless of direction of rotation.
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rotation of tibia During Tibial lateral rotation on the femur –
Medial tibial condyle moves slightly anteriorly on the relatively fixed medial femoral condyle, whereas lateral tibial condyle moves a larger distance posteriorly.
During tibial medial rotation –Medial tibial condyle moves only slightly
posteriorly, whereas the lateral condyle moves anteriorly through a larger arc of motion.
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During both medial and lateral rotation – The menisci reduce friction & distribute femoral
condyle force created on the tibial condyle without restricting the motion.
Meniscus also maintain the relationship of tibia & femoral condyles just as they did in flexion and extension.
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Valgus (Abduction)/Varus (Adduction) Axis – Antero-posterior axis Plan – Frontal plane ROM –
8 at full extension13 with 20 of knee flexion.
Excessive frontal plane motion could indicate ligamentous insufficiency
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Patello-femoral joint (pfj)
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pFj function
It work primarily as an anatomical pulley It reduce friction between quadriceps tendon
& femoral condyle. The ability of patella to perform its function
without restricting knee motion depends on its mobility.
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PFJ articulating surface
The triangular shape patella is a largest sesamoid bone in body is a least congruent joint too.
Posterior surface is divided by a vertical ridge into medial & lateral patellar facets.
The ridge is located slightly towards the medial facet making smaller medial facet
The medial & lateral facet are flat & slightly convex side to side & top to bottom.
At least 30% of patella have 2nd ridge separating medial facet from the extreme medial edge known as Odd Facet of Patella.
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Femoral articulating surface
Patella articulate in femur with intercondylar groove or femoral sulcus on anterior surface of distal femur.
Femoral surface are concave side to side & convex top to bottom but lateral facet is more convex then medial surface.
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PFJ congruence
The vertical position of patella in femoral sulcus is related to length of patellar tendon, approximately 1:1 is (referred to as Insall-Salvati index)
An excessive long tendon produce an abnormally high position of patella on femoral sulcus known as patella alta.
In neutral or extended knee, the patella has little or no contact with the femoral sulcus beneath.
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At 100 – 200 of flexion – contact with inferior margin of medial & lateral facet.
By 900 of flexion – all portion of patella contact with femur except the odd facet.
Beyond 900 of flexion – medial condyle inter the intercondylar notch & odd facet achieves contact for the first time.
At 1350 of flexion – contact is on lateral & odd facet with medial facet completely out of contact.
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Patello femoral joint stabilizer
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Medial-lateral PFJ stability
PFJ is under permanent control of 2 restraining mechanism across each other at right angel.Transvers group of stabilizerLongitudinal group of stabilizer
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Transvers stabilizer – Medial & lateral retinaculumVastus Medialis & LateralisThe lateral PF ligament contributes 53% of total
force when in full extension of knee.
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Longitudinal stabilization
Patellar tendon – inferiorly Quadriceps tendon – superiorly
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Medial-lateral positioning of patella / patellar tracking When the knee is fully extended & relax, the
patella should be able to passively displaced medially or laterally not more then one half of patella.
Imbalance in passive tension or change in line of pull of dynamic structures will substantially influence the patella.
Abnormal force may influence the excursion of patella even in its more secure location within intercondylar notch in flexion.
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Medial & lateral force on patella Since the action line of quadriceps & patellar
ligament do not co-inside, patella tend to pulled slightly laterally & increase compression on lateral patellar facets.
Larger force on patella may cause it to subluxation or dislocate off the lateral lip of femur.
Genu valgum increase the obliquity of femur & oblique the pull of quadriceps.
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Femoral anteversion & tibial torsion creates an increased obliquity in patella predisposing to excessive lateral pressure or to subluxation or dislocation.
Excessive tension in lateral retinaculum (or weakness of VMO) may cause the patella to tilt laterally.
Insufficient height of lateral lips of femoral sulcus may create patellar subluxation or fully dislocation, even with relatively small lateral force.
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Muscles of knee &
its function
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Muscles of the KneeArea One-joint Muscle Two-joint Muscle
AnteriorVastus Lateralis
Rectus Femorisvastus MedialisVastus Intermedialis
Posterior Biceps Femoris (Short)
Biceps Femoris (Long)Semimembranosus
SemitendinosusSartoriusGracilis
GastrocnemiusLateral Tensor Fascia Latae
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Muscles of Posterior Knee
Knee FlexorsSemimembranosus, Semitendinosus, Biceps Femoris (Long & Short Heads), Sartorius, Gracilis, Popliteus & Gastrocnemius Muscles
Flex + Tibial Medial Rotators
Popliteus, Gracilis, Sartorius, Semimembranosus & Semitendinosus Muscles
Flex + Tibial Lateral Rotator Biceps Femoris
Flex + Abductor
Biceps Femoris, Lateral Head Gastrocnemius & Popliteus
Flex + Adductor
Semimembranosus, Semitendinosus, Medial Head Gastrocnemius, Sartorius & Gracilis
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Muscles
posterior
thigh
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Knee flexor groups
7 muscles flex the knee [Semimembranosus, Semitendinosus, Biceps Femoris (Long & Short Heads), Sartorius, Gracilis, Popliteus & Gastrocnemius Muscles].
5 muscles of flexors (Popliteus, Gracilis, Sartorius, Semimembranosus & Semitendinosus Muscles) –They have the potential to medially rotate the tibia on a
fixed femurWhereas the biceps femoris is capable of rotating the
tibia laterally.
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Knee flexor groups cont…
The lateral muscles (Biceps Femoris, Lateral Head of Gastrocnemius, & Popliteus) Capable of producing valgus moments at knee
The medial muscles (Semimembranosus, Semitendinosus, Medial Head of Gastrocnemius, Sartorius & Gracilis) Can generate varus moments
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biceps femoris or Lateral Hamstring
Proximal attachments: By two heads: Long head – to the tuberosity of ischium, having
a common tendon of attachment with semitendinosus.
Short head – to the lower portion of shaft of femur & to lateral intermuscular septum.
Distal attachments: 2 heads unite to be attached to the head of fibula,
to the lateral condyle of the tibia & to the fascia of leg.
AXN: Hip extension & external rotation Knee flexion & external rotation.
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Semitendinosus or medial hamstring
Proximal attachment: Tuberosity of ischium, having a
common tendon with the long head of the biceps.
Distal attachment: Medial aspect of tibia near the
knee joint, distal to the attachment of the gracilis.
AXN: Hip extension and internal
rotation Knee flexion and internal rotation.
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semimembranosus
Proximal attachment: Tuberosity of the ischium
Distal attachment: Medial condyle of the tibia.
AXN: Knee flexion and internal rotation Hip extension and internal rotation.
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Gastrocnemius
Proximal attachments: Above the femoral condyles and span the knee joint
on the flexor side. The muscular portion of the gastrocnemius may be
seen contracting in resisted flexion of the knee. Because the gastrocnemius is more important as a
plantar flexor of the ankle than as a knee flexor Distal attachments:
To the posterior calcaneus
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Popliteus Proximal attachment:
By a strong tendon from the lateral condyle of the femur.
The muscle fibers take a downward medial course and are attached into proximal posterior portion of body of tibia.
Distal attachment: widespread in a proximal-distal direction,
giving the muscle a somewhat triangular shape. AXN:
Medial rotation and flexion of knee.
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Muscle passing medial knee
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Anterior Muscles
Quadriceps muscles comprise 4 muscles that cross the anterior kneeRectus femorisVastus lateralisVastus IntermedialisVastus Medialis
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Quadriceps muscle Functions –
Together, the 4 components of quadriceps femoris muscle function to extend the knee.
Rectus femoris being a 2 joint muscle, it also involved in hip flexion along with knee extension.
Angle of pull of Quadriceps –Vastus lateralis – Pull 350 Lateral to long axis of femurVastus Intermedius – Pull Parallel to Shaft of femur, making purest
knee extensor. Vastus Medialis – Pull depended on segment of muscle –○ Upper fibers Vastus Medialis Longus (VML) angled 150 – 180 Medially○ Distal fibers Vastus Medialis Oblique (VMO) angled 500 – 550 Medially
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Patellar Influence on Quadriceps Function Patella lengthens the MA of quadriceps by
increasing the distance of quadriceps tendon & patellar tendon from the axis of the knee joint.
The patella, as an anatomic pulley, deflects the action line of quadriceps away from the joint centre, increasing the angle of pull & enhancing extension torque generation.
Pull of quadriceps also creates anterior translation of tibia on femur increasing ACL restraint
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Quadriceps activities During weight-bearing When an erect posture is attained –
Minimal activity of quadriceps because the LOG passes just anterior to knee axis results in a gravitational extension torque that maintains the joint in extension.
In weight-bearing with the knee slightly flexed –The LOG pass posterior to knee joint axis As the gravitational torque tend to promote knee
flexion, the activity of quadriceps is necessary to counterbalance the gravitational torque and maintain the knee joint in equilibrium.
April 11, 2023 96Dr. Ratankhuman M.P.T., (Ortho & Sports)
LOG & Movement arm (MA) during squatting
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Quadriceps activities during non–weight-bearing The MA of resistance is minimal when the knee
is flexed to 900 but increases as knee extension progresses.
Therefore, greater quadriceps force is required as the knee approaches full extension.
The opposite happens during weight-bearing activities.
April 11, 2023 98Dr. Ratankhuman M.P.T., (Ortho & Sports)
LOG & Movement arm (MA) during non-weight bearing
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Quadriceps Strengthening:Weight-Bearing versus Non–Weight-
Bearing Weight-bearing quadriceps exercises as squat
& leg press resulted in a posterior shear force at knee throughout the entire ROM
There was No Anterior Shear anywhere in the ROM.
In contrast, anterior shear force in a non–weight bearing knee extension exercise maximal anterior shear occurring between 200 and 100.
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Quadriceps Strengthening:Weight-Bearing versus Non–Weight-
Bearing cont… A Posterior Shear Force was also found
during Non–Weight-Bearing Exercise, only between 600 and 1010 of flexion.
Weight Bearing Exercises are often prescribed after ACL or PCL injury because of less stressful, more like functional movements & safer than non–weight-bearing exercises.
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Other muscles helping knee extension The actions of the Gluteus Maximus
& Soleus Muscles can influence knee motion in weight-bearing.
Although they do not cross the knee joint, these muscles are capable of assisting with knee extension.
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Iliotibial Band or IT tract Proximally –
The IT band is from Tensor Fascia Lata (TFL), Gluteus Maximus & Gluteus Medius muscles.
Distally –Attach to lateral intermuscular
septum & inserts into the Anterolateral Tibia (Gerdy’s Tubercle).
IT band also attaches to patella via lateral PF ligament of lateral retinaculum.
ITB
GM
TFL
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AXN:Reinforcing anterolateral aspect of knee jointAssisting ACL in checking posterior femoral or
anterior tibial translation when the knee joint is nearly full extension.
With the knee in flexion, the combination of IT band, LCL & popliteal tendon increases the stability of lateral knee.
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AXN line for itb
In extended knee –IT band moves anterior to the knee joint axis.
In flexed knee –IT band moves posteriorly over the lateral femoral
condyle as the knee is flexed. The IT band, therefore, remains consistently
taut, regardless of hip or knee’s position.
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Knee joint stabilizers
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Stabilization of knee joint Classification of supporting structure of knee –
Functional – ○ Static stabilizer○ Dynamic stabilizer
Structural – ○ Capsular method○ Extra-capsular method
Location – ○ Medial joint compartment○ Lateral joint compartment
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Static stabilizer
It include the passive structures, such as – CapsuleLigaments –○ Meniscopatellar lig, ○ PF lig, ○ MCL & LCL, ○ ACL & PCL, ○ Oblique poplitial & ○ Transverse lig.
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Dynamic stabilizer
It includes following muscles & oponeuroses –Quadriceps femoris,IT band, Extensor retinaculum, Poplitius, Pes anserinus, Hamstrings and also Gastrocnemius
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Medial joint stabilizers
Structure includes –Medial patellar retinaculum, MCL, Oblique poplitial ligament & PCL
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Lateral joint stabilizers
The structure included in static & dynamic stabilization of knee – IT band, Biceps femoris, Popliteus, LCL, Meniscofemoral arcuate,ACL & Lateral patellar retinaculum
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Knee Joint Stabilizers
Direction Structures Functions
A-P/Hyperextensionstabilizers
• Anterior cruciate ligament• Iliotibial band• Hamstring muscles• Soleus muscle (in weight-
bearing)• Gluteus maximus muscle
(in weight-bearing)Limit anterior tibial (or posteriorfemoral) translation• Posterior cruciate ligament
• Meniscofemoral ligaments • Quadriceps muscle• Popliteus muscle• Medial & lateral heads of
gastrocnemius
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Knee Joint StabilizersDirection Structures Functions
Varus/valgus stabilizers
• Medial collateral ligament• Anterior cruciate ligament• Posterior cruciate ligament• Arcuate ligament• Posterior oblique ligament• Sartorius muscle• Gracilis muscle • Semitendinosus muscle• Semimembranosus muscle• Medial head of gastrocnemius muscle
Limits valgus of tibia
• Lateral collateral ligament• Iliotibial band• Anterior cruciate ligament• Posterior cruciate ligament• Arcuate ligament• Posterior oblique ligament• Biceps femoris muscle• Lateral head of gastrocnemius muscle
Limit Varus of tibia
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Knee Joint Stabilizers
Direction Structures Functions
Internal/externalrotational stabilizers
• Anterior cruciate ligament• Posterior cruciate ligament• Posteromedial capsule• Meniscofemoral ligament• Biceps femoris
Limit medial rotation of tibia
• Posterolateral capsule• Medial collateral ligament• Lateral collateral ligament• Popliteus muscle• Sartorius muscle• Gracilis muscle
Semitendinosus muscle• Semimembranosus muscle
Limit lateral rotation of tibia
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References
Joint Structure and Function: A Comprehensive Analysis, Fourth Edition, Cynthia C. Norkin, 2005
Joint Structure and Function: A Comprehensive Analysis, Third Edition, Cynthia C. Norkin
Clinical Kinesiology and Anatomy, Fourth Edition, Lynn S. Lippert, 2006
Basic Biomechanics of the Musculoskeletal System, third edition, Margareta Nordin