knee (L8)
During a non-weight bearing movement, from 90 to 0 degrees of knee flexion, which knee position has largest external torque demand? Why?
0 degrees largest moment arm
what are the contributing factors to screw home mechanism (3- which one is the primary factor)
1. primary- shape of medial femoral condyle 2. tension in acl 3. lateral pull of quadriceps
Common Mechanism of Injury: ACL Factors associated with a non-contact ACL injury 1. strong activation of the ____________ muscle over a moderately _________ or nearly _________ knee 2. a marked "__________ collapse" of the knee (dynamic Q-angle) 3.excessive ______________ rotation of the knee (i.e., the femur excessively rotated ____________ at the hip relative to a fixed tibia) so may attribute to reduced activation of hip ___________ (abd/add) and_____________ rotation (gluteus maximus)
1. quadricep/flexed/extended 2. valgus 3. external / internally/abductor/external
Screw-home Mechanism: Tibia-on-femur Extension (open chain) For an open chain knee extension, _____° _________(ER/IR) rotation of the tibia during the last _____ ° of extension
10 external 30
Normal Q angle: •Normal Q-angle for males is ____ to ____ degrees •Normal Q-angle for females is ____ to ____ degrees •An increased Q-angle is thought to create excessive____________ forces on the patella through a bowstring effect.
10-13 15-17 lateral
Screw Home Mechanism:Femur-on-tibia Extension (Closed Chain) (tibia is FIXED) •Full knee extension requires ____° femoral ____ (IR/ER) •__________ (lat./med.) femoral condyle completes rolling, gliding motion at ~_____° flexion •As extension continues,________ (lat./med.) condyle continues to glide, roll •Results in __________ (IR/ER) rotation of femur on tibia •The knee joint is "_______"
10/IR lateral/30 medial internal locked
Frontal Plane Anatomical Alignment •Normal alignment: _____°-______° •Abnormal alignment: 1. Excessive genu valgum (knock-knee) <_______° 2. Genu varum (bow-leg) >________°
170°-175° 165 180
Tibiofemoral Joint Osteokinematics •______ Degrees of Freedom (DOF) what are they? -e/f degrees: (__°- 0°- _____°)
2 •Extension/Flexion (5 °-0°- 140 °) •Internal/External Rotation
Patellofemoral Kinematics - Path (Patellar Tracking) •medial or lateral - shift (≈ __ mm) •From extension to flexion: first shift ____________ [med/lat] (≈ ___ ° flexion) then ___________ [med/lat](≈ ___° flexion) [30 OR 90 degrees of flexion for blanks] •Excessive lateral shift has been observed in people with___________ (ant/post) knee pain
3 medially; 30 laterally; 90 anterior
Meniscal Resection and Contact Area •Removal of menisci decrease contact area by a factor of ____ to ____ ↑ Stress (Load per unit area) •Leads to c___________ d_____________ and then to ________________
3-5 cartilage degeneration Osteoarthritis
Maximun torque generation when the knee joint angle in between ________ and _______ degrees of flexion
30 and 80
Patella Motion: __ Degrees of Freedom (__ translations/__ rotations)
6 DOF 3 translation: lat/med shift, sup/inf. shift, ant/post. shift 3 rotations: lat/med tilt, medial/lat rotation, anterior/posterior tilt
Common Mechanism of Injury: ACL •____ % non-contact injury •Many occur while landing from a jump, quickly and forcefully changing direction, decelerating, cutting or pivoting over a single planted lower limb
70
Posterior drawer test: Posterior pushing force with knee flexion at ______ °
90
Tibiofemoral Joint Osteokinematics Internal/External Rotation •max range at _______° flexion •______-____° total •ER:IR = ___:____
90 40-50 2:1
During a weight bearing movement, from 90 to 0 degrees of knee flexion, which knee position has largest external torque demand? Why?
90 degrees largest moment arm
unhappy triad knee injury
ACL, MCL, medial meniscus
Anterior Cruciate Ligament (ACL) prevents... •1. ___________ (primary) - 1a. Anterior translation of the_______ - 1b. Posterior translation of the _______ - 1c. Combination of both •2. ____________ and __________ stress •3. ________ rotation
Extension tibia femur Valgus/varus Axial
Name the extracapsular ligaments of the knee and the intracapsular ligaments?
Extracapsular Ligaments •Medial Collateral Ligament (MCL) •Lateral Collateral Ligament (LCL) Intracapsular Ligaments •Anterior Cruciate Ligament (ACL) •Posterior Cruciate Ligament (PCL)
Meniscal Movement during Knee Flexion/Extension Closed chain (weight-bearing), menisci follow Roll motion of ___________ •During extension, femur Rolls _____________ Thus, menisci move ____________. •During flexion, femur Rolls ____________. Thus, menisci move ____________.
FEMUR anteriorly anteriorly posteriorly posteriorly
Posterior Cruciate Ligament (PCL) Resists: •_________ (ext./flex.) - Posterior translation of the ________ - Anterior translation of the ________ - Combination of both •__________ and ________ stress •_________ __________
Flexion tibia femur Valgus/varus Axial rotation
The Menisci •External border of the lateral meniscus does NOT attach to _______ (only attaches to _________ _______)
LCL joint capsule
Anterior Cruciate Ligament (ACL) •2 portions: which is smaller and which is larger?
Larger posterior-lateral Smaller anterior-medial
Bony Morphology: Patella •___________ facet >___________ facet (lateral/medial) •The thick cartilage (up to 4-5 mm) helps to disperse the large __________________ force across the patellofemoral joint
Lateral>medial compression
what muscles actively control frontal plane motion (Abduction / Adduction)?
NONE
explain open and closed chain of tibiofemoral joint (which bone is mobile and action of IR/ER?)
OC: ext rot of tibia CC: int rot of femur
Most ______ injuries are associated with high-energy trauma (automobile accident)
PCL
how to calculate PFJ (patellofemoral joint) stress
PFJ Force divided by Contact Area
Consequences of ↑ dynamic Q angle: • patellofemoral p_____ • patellofemoral d___________ (patellar lateral tracking) •_______ (ligament) injury
Patellofemoral Patellofemoral ACL
The Menisci Muscle attachements (secondary) (3 muscles)
Quadriceps, semimembranosus and popliteus
global factors of patellofemoral joint (1 lateral, 1 superior, 1 inferior) - look at picture for reference
Sup - line of force of the quadriceps Lateral- bowstringing force on patella inferior- patellar tendon force
Meniscal Movement during Knee Flexion/Extension Open chain (non-weight-bearing), menisci follow Roll motion of _____________- •During extension, menisci move ____________ since tibia rolls ____________ •During flexion, menisci move ____________ since tibia rolls____________
TIBIA anteriorly/anteriorly posteriorly /posteriorly
Medial Collateral Ligament Resists forces in what direction? •________ stress (primary) •________/_________ rot. •posterior portion resists full ___________
Valgus Medial/Lateral rotation Full extension
Dynamic Q-angle •Dynamic Knee v___________ (valgus/varus) •Measured during d____________ tasks (ie drop jump, cutting...)
Valgus dynamic
↑ dynamic Q angle: •Causes: - ________ (smaller/wider) pelvis - Excessive femoral ______ (IR/ER) and hip ___________ (ABB/ADD), likely due to gluteal muscle weakness -___________ (med./lat.) tracking of patella
Wider IR adduction lateral
•Cruciate Ligaments (ACL, PCL) •Primary: ________/_______ stability •Secondary: ________/_______ stability •____________ stability
anterior/posterior medial/lateral Rotatory
The Menisci Increase contact area •Reduce stress (force/area) on a_________ c_________ •Enhance c_____________ of the tibiofemoral joint •Distribute w_________ b________ force
articular cartilage congruence weight bearing
EXTENSION femur on tibia is (open/closed) chain the tibia is (fixed/mobile) the femur rolls (ant/post) and slides (ant/post) and (external/internal) rotation the menisci moves (ant/post)
closed fixed ant post internal ant
The Menisci •Guide knee arthrokinematics (_________) [convex/concave] •Contribute to joint s__________ •Provide p_________________
concave stability proprioception
Medial Collateral Ligament Posterior portion: • (Superficial/Deep) •Extends (less/further) distally •Attaches to......... t________ c________, c_______, m________ m_________
deep less to tibial condyle, capsule, medial meniscus
Compare the joint compression force on the patellofemoral joint of a partial squat and a deep squat, which one is larger?
deep squat
the femoral condyles have greater joint congruency in ________________
extension
what is the close-packed position of tibiofemoral joint?
extension
what is the closed packed positon of the tibiofemoral joint?
extention
Cruciate Ligaments: Anterior and Posterior •Resist e_____________ of knee motion •Guide a____________________ •Posterior compared to Anterior •_______________ (stronger or weaker) •________________ (larger or small CSA)
extremes arthrokinematics Strong larger CSA
Collateral Ligaments: Medial and Lateral •Reinforce ____________ capsule of the knee joint •Function - Primary : prevent excessive ___________ plane motion •v__________ and v_____________ •Contribution greatest as knee ___________ (flexion/ext.) at about ___° - Secondary : •Resist ___________________ •Resist ______ ___________
fibrous frontal Valgus, varus flexes; 30 hyperextension axial rotation
Periarticular Connective Tissues Joint capsule and reinforcing ligaments •The f_________ capsule encloses both the __________________ joint and the ________________ joint (dotted line) •The capsule is reinforced by what 3 things?
fibrous tibiofemoral patellofemoral muscles, ligament and fascia
Screw Home Mechanism:Femur-on-tibia Extension (Closed Chain) (tibia is FIXED) •Popliteus: causing ____________ (flex/ext) and ________________ (IR/ER) of the femur, to "________ "the knee
flexion lateral rotation unlock
what is the effect of the quad on the ACL during full ext and knee flexed to 80?
full ext: taut ACL 80 degree flex: less taut also at flexion -quadriceps have a smaller moment arm -hamstrings (the acl's agonist) have a larger moment arm [compared to full ext.]
The Menisci: Blood Supply •The peripheral 1/3 of the menisci receives a direct source of blood from ______________ arteries (branches of the popliteal artery) •The inner 2/3 of the menisci is essentially a______________, receives nourishment only from s_________ f____
genicular avascular synovial fluid
•Antagonist of PCL: _________________ (especially at around ______° knee ________________)
hamstring 90 flexion
The Menisci •Anchored to the i________________ region of the tibia by their anterior and posterior horns •External border of the medial meniscus attaches to____________
intercondylar MCL
explain the different body mechanics that will increase or decrease stress on the ACL as you land from a jump
knee absorbs more impact L and hip absorbs more impact in R Basically to decrease impact on knee there needs to be more of a hip hinge, which causes a more forward trunk
Increased Q-angle, increased __________ pull on the patella
lateral
Q-angle •Represent the relative __________ pull of the quadriceps on the patella ....ONLY •Poor association with p__________ at the patellofemoral joint •_________________ (good/inadequate) standardized measurement protocol •Inability to measure d___________ alignment
lateral pathology Inadequate dynamic
Bony Morphology: Trochlea Groove Higher raised ___________ facet so steeper ___________ side
lateral lateral
local factors of patellofemoral joint (3 lateral directed forces, 3 medial directed forces, superior force, inferior force)
lateral directed forces -iliotibial band -lateral patellar retinacular fibers -bowstringing force on the patella medial directed forces -vastus medialis (oblique fibers) -raised lateral facet of the trochlear groove -medial patellar retinacular fibers Superior -overall line of pull of quads inferior -patellar tendon force
does using the hamstring along with the quad make the ACL have more or less tension?
less
Disparity Between Medial and Lateral Femoral Articular Surfaces •Articular surface: __________ > ___________ •Pure _________ plane motion fails to use entire articular surface •Requires motion in ____________ plane for rotation
medial > lateral sagittal transverse
Posterior Cruciate Ligament (PCL) •Orientation of PCL: From distal end to proximal: ___________,__________,____________ •2 portions: •Larger __________ set •Smaller ____________ set
medial, anterior, superior anterior posterior
Collateral Ligaments (MCL, LCL) •Primary: ________/_______ stability •Secondary: ________/_______ stability •____________ stability
medial/lateral anterior/posterior Rotatory
Different size and shape in the medial and lateral condyles of femur Size: ____________ condyle > ____________ condyle •medial condyle extends farther ________ (ant./post.) and curves about __°
medial>lateral anterior, 30
EXTENSION Tibia on femur is (open/closed) chain the femur is (fixed/mobile) the tibia rolls (ant/post) and slides (ant/post) and (external/internal) rotation the menisci moves (ant/post)
open fixed ant ant external ant
Bony Morphology: Trochlea Groove Articulate with the ______________ (larger lateral facet)
patella
what is the largest sesamoid bone in the body?
patella
Anterior Cruciate Ligament (ACL) proximal and distal attachment
proximal: lateral, posterior, superior on femur distal: anterior intercondylar
Patellofemoral Joint: Local Stabilizers •_______________ muscle •The f__ of the articular surfaces •Passive_______________ from the surrounding soft tissues (ligaments, tendons, retinaculums)
quad fit restraint
what is the antagonist of ACL?
quadriceps
Q-Angle (static) A measure of the overall line of pull from the ___________________ •This angle is formed in the __________ plane by two line segments: •From the _________ to the _______________ - representing the overall line of force by the quadriceps muscle. •From the___________________ to the _________________, representing the long axis of the patellar tendon
quadriceps frontal ASIS/mid-patella tibial tuberosity/mid-patella
Factors Associated with Joint Compression Force on the Patellofemoral Joint DEEP SQUAT = larger compression force 1. Force generated by the _____________ muscles (related to the external torque demand) 2.Knee flexion angle •__________ resultant force at larger flexion angle •__________ external torque demand at larger flexion angle
quadriceps Larger Larger
What are the knee extensors? (4)
rectus femoris, vastus lateralis, vastus medialis, vastus intermedius
there is variation in curvature of femoral condyles in ______________ plane
sagittal
Effects of the Quadriceps Muscle Acting on the Patellofemoral Joint •Compression force (__________ plane) •Provide dynamic patellar _________
sagittal stability
what are the knee flexors? (7)
semimembranosus, biceps femoris, semitendinosus, gracilis, plantaris, popliteus, gastrocnemius
Decreased patellofemoral joint stability when the patella locates at ________________ trochlea groove
shallower trochlea (larger sulcus angle- more proximal)
Bony Morphology: Trochlea Groove Larger sulcus angle... _____________ (deeper/shallower) groove at the more ___________ (proximal/distal) end
shallower, proximal
Bony Morphology: Tibia •Articular surfaces s__________ than those on femur •articular surface: ____________ tibial condyle > ____________ tibial condyle (lateral/medial)
smaller medial> lateral
Patellofemoral Joint •The patella functions as a "__________" between femur and quadriceps ----> increases internal moment arm of____________
spacer quadriceps
Medial Collateral Ligament Anterior portion: • (Superficial/Deep) •Extends (less/further) distally •Attaches to......... _________ _______ shaft
superficial further medial tibial
Patella Contact Areas at Different Knee Flexion Angles •As the knee extends, the contact point on the patella migrates from its ______________ pole to its _____________ pole. •↑ contact area with knee __________ (flex/ext)
superior inferior flexion picture depicts knee flexion angles and contact area of patella
Quadriceps is the prime mover of the patella, it pulls the patella into what direction? (3)
superior lateral posterior
Patellofemoral Kinematics - Path (Patellar Tracking) •Patella move _____________ (sup/inf) during extension, _____________ (sup/inf) during flexion (open chain) •Patella rests completely proximal to the trochlear groove in full ___________ (flex/ext)
superiorly inferiorly extension
Periarticular Connective Tissues •The ______________ membrane lies in the internal surface of the joint capsule •____________ and ___________ form at inter-tissue junctions that encounter friction during movement (ligament and tendon, muscle and capsule, bone and skin, tendon and bone, bone and muscle, bone and ligament)
synovial Bursae and fat pads
Closed-chain movement of patella: Patella stays relatively in place (because ________ is fixed on the ground)
tibia
Patella follows movement of ____________ (patellar tendon is non-contractile)
tibia
What force direction does the quadriceps produce during knee extension on the tibia and ACL? (Anterior or Posterior? slack/taut?)
tibia moves anterior and ACL is taut
Screw-home Mechanism Function
to achieve knees most stable position
Patellofemoral Joint Interface between the articular side of the patella and the ______________ _____________ of the femur
trochlear groove
Open chain movement of patella: During tibial-on-femoral movements, the patella slides relative to the fixed what?
trochlear groove of the femur
Proper motor control at the hip joint (abduction, external rotation) helps to prevent the "________________" at the knee
valgus collapse
what is the accessory (passive) motion of the tibiofemoral Joint?
valgus/varus
what are the knee external rotators? (1)
•Biceps Femoris -Long head -Short head
what are the knee internal rotators? (4 muscles, 3 have a common insertion site... what is it?)
•Pes Anserine (attachment site): (Sartorius, Gracilis, Semitendinosus) •Semimembranosus
Cruciate Ligaments: Anterior and Posterior •Provide stability in multiple directions what is the primary (1) and secondary (2)?
•Primary: anterio-posterior forces •Secondary: rotational, frontal plane stresses
Lateral Collateral Ligament •Resists ______ stress (primary) __________/____________ rot. full _________________
•Varus stress (primary) •Medial/Lateral rotation •Full Extension
Lateral Collateral Ligament Attachments (2) Where are there NO attachments to (2)?
•lateral epicondyle of femur and Head of fibula •NO attachments to meniscus or capsule