Kin 2 - Knee
Superficial layer - Chondrocytes and collagen fibers are tangential/parallel to the surface - Provides resistance to shear forces crossing the surface of the joint Middle Layer - haphazard/random arrangement of cells and fibers. - Provides resistance in any direction Deep layer - Cells and fibers are ________ to the surface and resists ________ forces
- perpendicular - compressive
Valgus force Secondary restraints:
- posterior-medial capsule - semimembo - ACL / PCL - compression of lateral meniscus - pes anserine - medial gastroc head
The _______ bundle of the ACL is taut in extension and provides the greatest restraint to anterior translation until about 20 degrees of flexion
- posterolateral
The sides of the trochlear groove are called lateral and medial facets - lateral is more pronounced - extends more _________and _________, than the medial facet.
- proximally - anteriorly
A ________ bone is a small round bone that is imbedded within a tendon, whose purpose is to reinforce and decrease stress on that tendon.
- sesamoid ***patella is the biggest sesamoid bone we have***
Patella - Largest _________ bone in body - Curved base and pointed apex ________ - Posterior surface covered with ________ up to 4-5 mm thick. - Posterior surface articulates with femur forming the patella femoral joint. - Medial and lateral facets match the general contour of the femur.
- sesamoid - inferiorly - articular cartilage -
There are about 14 bursa in the knee - most prominent are the ________ and ________ bursa.
- suprapatella - deep infrapatella
Superficial layer - Chondrocytes and collagen fibers are _________ to the surface - Provides resistance to ________ forces crossing the surface of the joint Middle layer - Haphazard arrangement of cells and fibers. - Provides resistance in any direction Deep layer - Cells and fibers are perpendicular to the surface and resists compressive forces
- tangential (parallel) - shear
3 factors contributing to the "screw-home" mechanism:
- tension of ACL - shape of medial femoral condyle - lateral pull of quads
Primary role of the _________ is to transfer weight across the knee to the ankle.
- tibia
Biceps femoris (long head) innervation and plexus
- tibial nerve L5 S1 S2 - sacral plexus
Gastroc innervation and plexus
- tibial nerve S1 S2 - sacral plexus
3 contact surfaces in the knee joint structures: - patellofemoral region - Medial and Lateral compartment in _______ articulation
- tibiofemoral
Q angle increased laterally and decreased medially is genu _________
- varum
- Q angle (measured laterally) greater than 170-175 is considered genu _______ - Q angle (measured laterally) smaller than 165 and below is is considered genu _______
- varus - valgus
Patellofemoral compression forces - 1.3 times body weight during ________ - 2.6 times body weight during ________ - 3.3 times body weight during ________ - 7.8 times body weight during ________ Reaching a maximum between _______ degrees of flexion
- walking - SLR - climbing stairs - deep squats - 60-90
- most fibers resist extension - resist anterior translation of tibia - resist posterior translation of femur - resists extreme valgus, varus, axial rotation Refers to ______ ligament
ACL
Posterior lateral capsule of the knee is reinforced by the arcuate popliteal ligament, LCL and popliteus muscle, which is known as the _________ - If damaged can create unwanted transitory motion from a biceps femoris contraction since the fulcrum is unstable
Arcuate Complex
True or false? The oblique popliteal ligament is included in the Arcuate Complex (posterior lateral capsule)
False . It includes: - LCL - popliteus - arcuate popliteal ligament
Sartorious innervation and plexus
Femoral Nerve L2-L4 - lumbar plexus
__________ separates the lateral and medial condyles forming passageway for the cruciate ligaments - narrow notch may increase risk of ACL injury
Intercondylar notch
- resists valgus - resists knee extension - resists extreme knee ER Refers to _______ ligament
MCL (also the posterior medial capsule)
In youth, Apophyseal plates have not sealed yet - as they use quads, there is increased pulling at Tibial tuberosities, can cause somewhat of an avulsion - can cause injury in rapidly growing adolescents Refers to ________ disease
Osgood-Schlatter Disease
- most fivers resist knee flexion - resist posterior translation of tibia - resist anterior translation of femur - resists extremes of varus, valgus, axial rotation Refers to _______ ligament
PCL
Knee has only _______ motion in the frontal plane
Passive
- resists knee extension - OPL resists ER - _______-lateral capsule resists varus Refers to _______ capsule
Posterior capsule - posterior
- MCL - LCL - OPL (oblique popliteal lig) - posterior medial capsule Are going to be ________ during knee flexon
Slackened *ACL is still somewhat elongated during flexion
Popliteus innervation and plexus
Tibial nerve L4 L5 S1 - sacral plexus
Plantaris innervation and plexus
Tibial nerve S1 S2
True or False? The fibula has no direct weight bearing function at the knee.
True
Q angle decreased laterally and increased medially is genu _______
Valgum
- biceps femoris - tendon of Popliteus - lateral head of gastroc - IT band - LCL Will be taut by a ______ force at the knee
Varus
After post-op ACL - avoid open chain activity______ degrees flexion - avoid closed chain activity ______ and more of flexion
- 0-30 - 60
Articular Cartilage - mostly made of type 2 collagen and chondroitin sulphate Usually arranged in 3 layers: - Superficial (_______% of cells) - Middle (_______% of cells) - Deep ( _______% of cells)
- 10-20% - 40-60% - 30%
Q angle (measured medially) - is a measurement of the angle between the Rectus Femoris / ASIS and the patella tendon - Average for men -_______° - Average for women - _______°
- 11.2 - 15.8
Sulcus angle - from highest peaks of the medial and lateral femoral condyles to the deepest part of the trochlear groove. Normal is ______ degrees +/- 6 degrees) - A more shallow groove may predispose a person for patella dislocation.
- 138
- Joint congruency is in knee flexion from _____to _____ degrees - Full extension is when posterior capsule is taut
- 15-30
Articular Cartilage - mostly made of type ______ collagen and ______ sulphate Usually arranged in 3 layers: - Superficial (10-20% of cells) - Middle (40-60% of cells) - Deep ( ~30% of cells)
- 2 - chondroitin
Compression at the knee - Compression forces at the knee routinely reach ______ to ______ times body weight while ascending stairs. - By nearly tripling the area of joint contact, the menisci significantly reduce the pressure (force per unit area) on the articular cartilage. - A complete lateral meniscectomy has been shown to increase peak contact pressures at the knee by _______%
- 2.5 to 4 - 230%
The posterolateral bundle of the ACL is taut in extension and provides the greatest restraint to anterior translation until about ______ degrees of flexion
- 20
Maximum leverage for the IMA of the knee is between ______ and ______ degrees of flexion
- 20 and 60
The anterior medial bundle of the ACL is taut from _______ to _______ degrees of flexion
- 20 to 90 degrees
In the knee, we get ER of the tibia (or IR of the Femur) during the last ______ degrees of Extension - during this, were get ________ degrees of ER
- 30 - 10
______% of all acute injuries of ACLs are associated with meniscal injury MOI: forceful axial rotation with a partially _______ knee while weight-bearing
- 50% - flexed
hamstrings play a big role in preventing anterior translation of the Tibia - but after about ______ degrees, there is less hamstring pull and may result in more anterior translation of tibia
- 60
Menisci are fibrocartilaginous disks located on the tibial plateau that disperse weight bearing forces. - During activities, the menisci can manage up to______% of the load on the knee.
- 70%
Anterior Drawer test for ACL tear is done with _______ degrees of knee flexion and tests the ________ bundle
- 90 - anteriomedial
GAGs, glucosamine, chondroitin help preserve whatever ________ is left
- Articular cartilage
- Patella ________ may result in patella being compressed into the trochlea groove during knee flexion - Patella Alta may result in the patella coming out of the groove too soon and possibly dislocating
- Baja - Alta
Screw-home mechanism - In Closed chain knee flexion (descending into squat) the femur will _______ while the tibia goes into relative _______ - In Closed chain knee extension (coming out of squat) the femur will ______ while the tibia goes into relative _______ ****** follows the actions of the Popliteus******
- ER - IR - IR - ER
Superficial layer - Chondrocytes and collagen fibers are tangential/parallel to the surface - Provides resistance to shear forces crossing the surface of the joint Middle layer - _______ arrangement of cells and fibers. - Provides resistance in ________ direction Deep layer - Cells and fibers are perpendicular to the surface and resists compressive forces
- Haphazard/random - any
The menisci deform peripherally as they are compressed - This mechanism allows part of the compression force at the knee to absorbed as a circumferential tension known as ________ - A tear of the meniscus especially the posterior horn loses it's ability to resist compression
- Hoop Stress 🏀
Screw-home mechanism - In Open chain knee flexion the tibia will _______ while the femur goes into relative _______ - In Open chain knee extension the tibia will ______ while the femur goes into relative _______
- IR - ER - ER - IR
- resists varus - resists knee extension - resistances extreme axial rotation Refers to ________ ligament
- LCL
Varus Force Primary restraint:
- LCL
Varus forces will make what structures taut?
- LCL - lateral patellar retinacular fibers - IT band - muscle fibers (biceps fem, Popliteus tendon, lateral head of gastroc)
A valgus force at the knee will make what structures taut?
- MCL - Medial Patellar retinacular fibers - muscles (semimembo, sartorious, Gracilis, semitendo)
Valgus force Primary restraint:
- MCL especially the superficial fibers
________ meniscus is twice as frequently injured - Associated with a valgus force - Attachment to the _______ - mostly posterior
- Medial - MCL
Congruency angle Measures the patella's position in the trochlear groove relative to the midpoint of the sulcus angle - If medial the number is patella's position in the trochlear groove relative to the midpoint of the sulcus angle compared to the lowest portion of the patella ridge. - if medial, the number is ________ A tilt greater than _______ would mean the patella is sitting lateral
- Negative 6 - positive 16
Gracilis innervation and plexus
- Obturator nerve L2 L3 - lumbar plexus
Femur is naturally angled medially Can be measured via the _______ - effected by the angle of inclination of the proximal femur - Articular surface of the tibia is nearly horizontal - Knee forms a normal _______ degree angle
- Q-angle - 170-175
What are 3 factors contributing to ACL tears?
- Strong quadriceps contraction - genu valgum collapse - Excessive rotation (femur in IR - tibia into ER) *also consider midfoot pronation + knee valgus*
Semitendo innervation and plexus
- Tibial nerve L5 S1 S2 - sacral plexus
PCL has a larger _________ bundle, and a smaller ________ bundle - Most taut in ______to______degrees of flexion - Hamstrings act as a PCL antagonist
- anterolateral - posteromedial - 90-120
Varus Force Secondary restraints
- arcuate complex (LCL, popliteus, arcuate popliteal ligament) - IT band - Biceps femoris - joint contact medially - compression of medial meniscus - ACL/ PCL - gastroc lateral head
What is the arcuate complex (posterior lateral capsule) comprised of? - If damaged can create unwanted transitory motion from a biceps femoris contraction since the fulcrum is unstable
- arcuate pop ligament - LCL - popliteus muscle
A varus force with extension at the knee will make what 3 structures taut?
- arcuate popliteal ligament - LCL - popliteus (muscle)
Biceps femoris (short head) innervation and plexus
- common fibular nerve - L5 S1 S2 - sacral plexus
Proximal Tibia The larger medial articular surface is slightly _______, where as the lateral articular surface is flat to slightly ________.
- concave - convex ***However the meniscus helps with concavity, in order for the lateral femoral condyle to be able to sit in the lateral condyle of the tibia***
Lachlan's test for ACL tear is done is knee ________ (almost full) and is tests for the ________ bundle
- extension - posterolateral
Menisci are ________ disks located on the tibial plateau that disperse weight bearing forces. - During activities, the menisci can manage up to 70% of the load on the knee.
- fibrocartilaginous
50% of all acute injuries of ACLs are associated with meniscal injury MOI: forceful axial rotation with a partially _______ knee while _______
- flexed - weight bearing
The quadriceps and the patellar retinacular fibers will be taut by _______
- flexion (at the knee)
- MCL - LCL - OPL (oblique popliteal lig) - posterior medial capsule Are going to be slackened during knee ________
- flexon *ACL is still somewhat elongated during flexion
- Articular cartilage is made out of ________ - Meniscus is out made out of ______
- hyaline - fibrocartilage
The anterior and posterior horns attach to the _________, in addition to the ACL and PCL
- intercondylar eminence
Proximal Tibia The larger _______ articular surface is slightly concave, where as the _______ articular surface is flat to slightly convex.
- medial - lateral
Plicae - Most common described are superior/suprapatellar, inferior and medial plica - _______ plica appears to be the most problematic may cause abrasion of the articular cartilage of the _______ femoral condyle.
- medial - medial
a full extension force + ER will make what 3 structures taut?
- oblique popliteal ligament - arcuate popliteal ligament - muscles (popliteus, gastroc, hamstrings)
ACL limits tibial anterior translation So in ______ chain, during the last 20 degrees towards extension, there is a lot of shear force on ACL and is not advised for a newly repaired ACL tibial tuberosity and the quadraceps pull is more in line with the moment arm for extension and results in more shear forces of the tibia on the femur
- open
In ________ chain, we have no external torque on our knee when it is flexed to 90 degrees In _______ chain, we have a LOT of external torque on our knee when we are flexed to 90 degrees
- open - closed
Red Zone of Meniscus - located on the outer edge of the meniscus. - The tears in the red zone tend to heal quicker because they have access to good blood supply. - Small tears can be healed by using non-surgical treatments, such as a brace.
- outer
