MS Exam 2: Knee
What is the anterior drawer test used for? How is it performed?
ACL injury flex knee 90 degrees sit on patients foot to stabilize Grasp patients posterior knee palpate anterior surface of the tibia with one or both thumbs provide a firm anterior pull to the knee assess for ligamentous laxity and quality of end feel
A normal quadriceps angle is between __ and ___ degrees.
10-15
Quadriceps cross-sectional area are about __ larger than the hamstrings.
2x
Peak torque in knee flexion occurs around ___ to ___ degrees.
45-60 degrees
Quadriceps peak torque is about ___ to ___ degrees.
45-70 degrees
Most rotation of the knee is available at ___ degrees.
90 degrees *lateral 0-20 degrees medial 0-15 degrees
MYTH: Individuals with knee pain should decrease their PA, since this places added pressure on joints and can exacerbate the issue. Why is this a myth?
Can be true, but we know of ways that we can decrease stress with different exercises thinking about where the line of gravity falls through the joint, and minimizing the moment arm
____ between the patella and femur changes throughout ROM.
Congruence (contact)
What is the valgus stress test used for?
MCL injury Hold ankle of involved limb with outside hand opposite hand placed over the medial joint line of the involved limb knee flexed 20-30 degrees apply valgus force by abducting the tibia and stabilizing the thigh test is repeated in full extension
MYTH: Weight bearing exercises are better after ACL reconstruction. Open-chain (e.g., leg extension) exercises should due to increased strain on ACL. Why is this a myth?
Open chain exercises can be less strain than doing a full squat, but later on we actually need to increase stress for them to get back to normal activity.
The ACL provides the primary restraint to....
anterior translation of tibia on femur
The anterior cruciate ligament are consisted of 2 bands: ____ and ____
anteromedial and posterolateral bands
What are the consequences of a meniscectomy?
arthritis breakdown of articular cartilage can't distribute forces appropriately
Medial and lateral rotation of the knee is permitted by....
articular incongruence and ligament laxity
The medial collateral ligament is lax as you flex the knee, but provides more support. Why?
because of the lateral rotation
The knee joint lateral rotator muscle is the:
bicep femoris
In a bilateral stance, the ground reaction force passes from the ____ to the ____.
center of ankle to center of hip joint *forces distributed about equally between medial and lateral condyles
On the femur, the condyles are ____.
convex
After a meniscectomy, the contact area in the tibiofemoral joint is ____, resulting in more stress on the ____.
decreased articular cartilage (2x femur, 6-7x tibial plateau)
What structures provide passive support of the medial aspect of the joint capsule?
deep and superficial MCL
The tibiofemoral joint is a ____ type joint and has ___ degrees of motion.
double condyloid joint 3 DoF (flexion/extension, medial lateral rotation, abduction/adduction) *mainly moves like a hinge joint
The joint capsule of the knee provides stability by restricting...
excessive joint motion *reflexive muscular response
Quadriceps ____ the knee, but provides ____ control during knee flexion.
extends the knee eccentric control
The posterolateral band of the ACL is taut in ___.
extension
The posteromedial bundle of the PCL is taut with ____.
extension
During non-weight bearing exercise, the quadriceps must generate more torque as the knee approaches full ____.
extension *increasing moment arm of the resistance
The lateral collateral ligament is ___capsular.
extracapsular (separate from joint capsule)
In normal tibiofemoral alignment, the femur is _____ and the tibia is _____.
femur is oblique and directed inferiorly and medially tibia is almost vertical
The menisci is a ______ disc.
fibrocartilaginous
Movement is described relative to ___ segment.
fixed segment
The tibia is relatively ___, but slightly ____.
flat, slightly convex
During weight bearing exercise, the quadriceps must generate more torque as the knee ____.
flexes *increasing moment arm at knee joint (distance from GRF)
THe anterolateral bundle of the PCL is taut with ___.
flexion
The anteromedial band of the ACL is taut in ___.
flexion
The medial collateral ligament has a ____ supply, which means it has the capacity to...
good blood supply capacity to heal
The knee joint flexor muscles are the:
hamstrings (semitendinosus, semimembranosus, biceps femoris) sartorius gracilis popliteus gastroc plantaris
What structure provide passive support of the lateral aspect of the joint capsule?
iliotibial band
What are the functions of the menisci?
improve tibiofemoral congruence (forms concavities for femoral condyles and increases contact area) distributes weight bearing forces (50-70% load) reduce friction proprioception
Patellofemoral joint forces continue to ____ as you go from 0-90 degrees of knee flexion, which also results in ____ contact area.
increase increased
The patella ____ the moment arm of the quadriceps.
increases *by increasing the distance of the quad tendon and patellar tendon (ligament) from the axis of the knee joint *if someone does not have a patella, the have to produce more force of their quads because of their shorter moment arm
In the patellofemoral joint, progressive flexion to 90 degrees increases contact area ___ to ____.
inferior to superior
The anterolateral ligament provides a primary restraint to the...
internal rotation of the tibia
The ACL and PCL are ___capsular, but ___synovial.
intracapsular extrasynovial.
During tibiofemoral flexion, small amounts of anteroposterior displacements occur due to...
joint incongruence and variations in ligamentous elasticity *axis of rotation is not fixed *not a perfect sphere
Patellofemoral joint forces can be influenced by...
knee angle quadriceps tension *large joint forces or small contact area
The ACL provides a secondary restraint for knee _____, ____ and ____.
knee hyperextension, varus, and valgus
During neutral femur/tibia alignment, weight bearing line (ground reaction force) passes through....
knee joint center, relatively equal loading
During genu valgum, there is greater loading in the ____ compartment.
lateral
The ___ meniscus covers a greater portion of the smaller tibial surface.
lateral
Quadriceps have a slight ____ pull.
lateral pull
The Screw Home (locking) mechanism explains the obligatory _____ of the tibia with knee extension.
lateral rotation *opposite occurs with flexion (medial rotation) *the shorter lateral tibial plateau and lateral femoral condyle completes the rolling motion before the longer medial structures
The lateral collateral ligament provides a secondary restraint to excessive...
lateral rotation of the tibia
Excessive motion in the knee may indicate....
ligamentous laxity or instabilty
Why is the knee unable to rotate in full extension?
maximum congruence of the joint (closed pack)
During genu varum, there is greater loading in the ___ compartment.
medial
The ___ meniscus has more ligamentous and capsular restraints.
medial
During medial/lateral rotation of the knee, the ___ compartment is the axis of rotation.
medial *medial meniscus reduces friction
In a unilateral stance, thr ground reaction force passes through the ___ compartment.
medial *creates more torque through medial aspect
The ___ meniscus is C-shaped, and the ___ meniscus is 4/5 of a circle.
medial lateral
The ___ aspect of the patellofemoral joint has larger forces, and can reach ____ body weight with running and jumping.
medial 5-6x body weight
Why is medial compartment knee OA more common than lateral?
medial compartment is the center of rotation more forces fall in the medial compartment during unilateral stance
On the femur, the ___ condyle extends further distally than the ___ condyle.
medial extends further than lateral
The ___ tibial plateau is larger relative to the ____ tibial plateau.
medial is larger than lateral
What 2 structures provide passive support of the anterior aspect of the joint capsule?
medial patellofemoral ligament (MPFL) and lateral retinacula (deep layer)
On the tibia, the ____ improves joint congruence.
menisci
MYTH: Running can increase the risk of developing knee OA. Why is this a myth?
more force through knee joint doesn't mean you will develop OA sitting on the couch can also increase risk
During closed chain extension, the glide occurs in the ___ direction of the moving segment (femur).
opposite *convex is moving on concave
In menisci, the _____ portion has neurovascular supply, and the ___ portion relies on diffusion of synovial fluid for nutrient exchange.
outer 1/3 (decreases with age) central portion (requires intermittent loading)
___ is the largest sesamoid bone in the body
patella
Menisci is thicker along the ____.
periphery
The knee joint medial rotator muscles are:
popliteus semimembranosus semitendinosus sartorius gracilis
In the synovial layer, the ____ aspect of the joint is separate from the fibrous joint capsule.
posterior
What 2 structures provide passive support of the posterior aspect of the joint capsule?
posterior oblique ligament and arcuate ligament
The PCL provides primary restraint to...
posterior tibial translation on the femur *able to withstand forces furing knee flexion
The posterior cruciate ligament is consisted of 2 bands: ____ and ____
posteromedial and anterolateral bands
The patella acts as an anatomical ___, and increases ability of muscle to generate ____.
pulley torque
The glut max is a weight bearing secondary knee extensor by...
pulling the femur posteriorly *posterior shear requires co-contraction of other muscles
The soleus is a weight bearing secondary knee extensor by...
pulling the tibia posteriorly
The knee joint extensor muscles are the:
quadriceps (rectus femoris, vastus medialis/lateralis/intermedius)
During open chain extension of the knee, the glide occurs in the ____ direction of the moving segment (tibia).
same *concave is moving on convex
The anterolateral ligament is a ____ of the lateral joint capsule, and attaches to the ____.
thickening lateral meniscus
On the tibia, the articular cartilage is thicker on the ____ tibial plateau relative to the ___ tibial plateau.
thicker on lateral than medial
What joints make up the knee?
tibiofemoral and patellofemoral
An osteotomy is the surgical adding or removal of bone. What is the purpose of this? (knee)
to move the weight-bearing line to other compartment; redistribute the loads across the knee joint
The medial collateral ligament provides restraint to ___force, and ____rotation of the tibia.
valgus force lateral rotation
The PCL provides secondary restraint to knee __ and ___.
varus and valgus
The lateral collateral ligament provides restraint to ___force.
varus force
During knee extension, the vastus muscle group provides ___ of torque, and rectus femoris provides ___ of torque.
vastus - 80% RF - 20%
MYTH: You can selectively recruit the vastus medialis. Why is this a myth?
you just can't
What is genu verum?
*bow leg <175 degrees
What is genu valgum?
*knock knee > 185 degrees
What is dynamic valgus?
Hip internal rotation coupled with knee external rotation (knee collapses inward) *increased patellofemoral contact forces - potential pain generator *consistent mechanism of injury (PFPS, ACL, IT band)
How could you use both NWB and WB exercise types to address lower extremity weakness while initially minimizing knee joint loading/stress?
NWB: seated leg extension, adding resistance bands or weights to progress, TRX bands to unload, aquatic exercises WB: squats, sit to stands, mini squats (shorten ROM)
Non-weight bearing movement of the knee is when the ___ is moving on the fixed ____.
Non-weight bearing movement of the knee is when the tibia is moving on the fixed femur.
What interventions can be used to reduce loads across medial knee?
Strengthening hip abductors to stabilize and reduce load on medial knee Modifying gait Unloader brace Decrease gait velocity Lose weight Lateral wedge orthotic Bias the line of gravity towards lateral compartment (shorten moment arm) Cane - increase base of support
What is the Lachman's test use for? How is it performed?
Test for ACL injury stabilize anterior surface of distal femur flex knee 20-30 degrees place other hand on posterior surface of proximal tibia apply an anterior translatory force through the tibia
The joint capsule of the knee encloses the ____ and ___ joints, and is ____ to synovial lining.
The joint capsule of the knee encloses the tibiofemoral and patellofemoral joints, and is superficial to synovial lining. *large and lax
The lateral collateral ligament becomes taut in full knee ____, and becomes lax with knee ____.
The lateral collateral ligament becomes taut in full knee extension, and becomes lax with knee flexion.
The medial collateral ligament becomes taut in full knee ____, and becomes lax with knee ____.
The medial collateral ligament becomes taut in full knee extension, and becomes lax with knee flexion.
The ___ condyle is larger and has a greater radius of curvature than the ___ condyle.
The medial condyle is larger and has a greater radius of curvature than the lateral condyle.
Weight bearing movement of the knee is when the ___ is moving on the fixed ____.
Weight bearing movement of the knee is when the femur is moving on the fixed tibia.
The medial collateral ligament provides secondary restraint to...
anterior tibia translation and medial tibia rotation
