The Knee
what is a normal Q-angle measurement?
13-18 degrees
knee ROM
0 degrees of ext to 120-135 degrees of flexion
hyperextension
0 to -5 degrees
An individual with a spinal cord injury at L3 would be expected to have what knee motion?
Weakened knee extension and no knee flexion.
what is a baker's cyst
a collection of excessive synovial fluid in the popliteal space
When assessing the knee collateral ligaments, the examiner pulls laterally on your ankle while pushing medially on your knee. a. What type of load is placed on your lower extremity? b. Which side of your knee undergoes a tensile stress? c. Which side of your knee undergoes a compressive stress?
a. Bending b. Medial side c. Lateral side
Identify the sequence of knee motions (starting with the knee in extension) for kicking a ball and identify the activity of the rectus femoris during each phase. a. What is the knee motion when preparing to kick? b. Over what joints is the rectus femoris being elongated? c. What is the knee motion when making ball contact? d. What is happening to the rectus femoris at the knee during ball contact? e. What is the knee motion during follow-through? f. What is happening to the rectus femoris during follow-through?
a. Bringing knee into flexion and hip into hyperextension b. Hip and knee c. Knee extension and hip extension d. Shortening at the knee but is still elongated at the hip e. Extension f. Shortening over both joints
What is the sequence of right-knee motions when stepping up onto a curb leading with the right foot, starting with the right knee extended? a. Placing right foot up on curb b. Bringing left foot up on curb
a. Knee flexion b. Knee extension
Describe the knee joints: a. Number of axes: b. Shape of joint: c. Type of motion allowed:
a. Knee: 1 Patellofemoral: 0 b. Knee: hinge Patellofemoral: irregular c. Knee: flexion/extension Patellofemoral: gliding
What compensatory motions may occur when stepping up onto a curb if your right leg were in a long leg cast? a. Which would be the leading leg? b. What pelvic motion would assist in getting the right leg up onto the curb?
a. Left foot b. Hip hiking
popliteal space
contains important nerves and blood vessels
is the distal femur convex or concave
convex
Which bones make up the knee joint?
Femur and tibia
Why is the action of the popliteus muscle often described as "unlocking" the joint?
It initiates knee flexion, moving the knee out of the "locked" position of extension.
Describe knee joint motion in terms of planes and axes.
Knee flexion and extension occurs in the sagittal plane around the frontal axis.
which 2 lines create the Q-angle?
Line from ASIS to midpoint of patella & Line from tibial tuberosity to midpoint of patella
which collateral ligament is bigger
MCL
with closed chain extension ROM, which direction will the femur glide as the knee moves into extension?
femur will glide posteriorly
what type of tissue is the meniscus
fibrocartilage
pes planus
flat footed
what is a bursa
fluid-filled sac that is present between skin and tendon or tendon and bone
describe valgus at the knees
genu valgus; the distal end of the tibia is lateral to proximal end in standing (knee knocked)
describe varus at the knees
genu varus; the distal end of tibia is medial to proximal end in standing (bow legged)
list the dynamic factors that affect Q-angle
hip abductor muscle weakness, hip extension rotator muscle weakness, pes planus, poor proprioception
what is the function of the meniscus
improve joint congruency and help with shock absorption
The greater the Q-angle:
increased risk to develop osteoarthritis on 1 side of knee; more likely to have MCL, ACL, or LCL tear; increased patellofemoral issues
largest joint in the body
knee
proprioception
knees bow due to lack of hip abductor muscles
what motion does the LCL limit
lateral (varus) movement of tibia on femur
anterior cruciate ligament (ACL)
limits anterior slide of femur on tibia; tightens during extension
posterior cruciate ligament (PCL)
limits posterior slide of femur on tibia; tightens during flexion
at the knee, which condyle is bigger: medial or lateral?
medial
what motion does the MCL limit
medial (valgus) movement of the tibia on femur
list 3 joints of the knee
medial tibia and femoral joint, lateral tibia and femoral joint, patellofemoral joint
what factors cause patellofemoral pain syndrome?
mispositioning of patella in femoral groove causes compression/weak&tear/pain of lateral patella/femur. Caused by excessive Q-angle, quad weakness, hip abductor/rotator weakness, poor flexibility of IT Band or hip flexor mm's
medial meniscus
more often injured as it is attached to MCL
Genu recurvatum
more than 5 degress of hyperextension
What is Osgood-Schlatter disease? Who gets it?
occurs in adolescents from high forces from patellar tendon pulling on tibial tubercle. the epiphysis of the tibial tubercle grows anteriorly, away from tibia
what happens when a patient lacks terminal knee extension
patient can't lock knee, doesn't like to stand for long periods of time, looks for a chair to sit down
list the anatomic factors that affect Q-angle
pelvis width, femoral anteversion or retroversion, genu valgus, genu varus
what is the area of the posterior knee called
popliteal fossa
which muscle unlocks the screw home mechanism of the knee
popliteus muscle
what motion does the PCL limit
posterior motion of the tibia on femur
most common bursitis seen in physical therapy
prepatellar, deep infrapatellar, infrapatellar
why is Q-angle important in physical therapy
provides useful information about the alignment of the knee joint
which of the 4 quad muscles does not originate on the femur
rectus femoris
list the 4 quadriceps muscles
rectus femoris, vastus medialis, vastus lateralis, vastus intermedialis
what is the function of a bursa
reduces friction between moving structures
pes anserine muscle group
sartorius, gracilis, semitendinosus
which 3 muscles insert at the pes anserine
sartorius, gracilis, semitendinosus
list the 3 hamstring muscles
semitendinosus, semimembranosus, biceps femoris
2 types of end-feel at knee joint
soft tissue approximation and soft tissue stretch
When performing passive range of motion on an individual's knee, the end feel for flexion should be ___and ___ for extension.
soft; firm
patellofemoral joint
synovial joint, articulation between femur and patella
most injured joint in the body
the knee
which joint has motions in sagittal and transverse plane
the knee
what is the purpose of the patella
the patella functions as a pulley, providing a mechanical advantage for the quads
flexion ROM
tibial will glide posteriorly on femur as knee goes into flexion
importance of screw home mechanism
when knee is locked, an individual can stand upright for long periods of time with essentially no muscle effort needed
when is the patella least engaged in the intercondylar groove of the femur?
when the knee extends
when is the patella most engaged in the intercondylar groove of the femur?
when the knee flexs
what is the biomechanical advantage of the screw home mechanism?
when the knee is 'locked', an individual can stand upright for long periods of time with essentially no muscle effort needed
how many bursae in the knee
~13
what is the meniscus?
1/2 moon wedge shaped disk on the superior surface of tibia
in an open chain situation, is convex moving or concave moving?
concave is moving
which 2 ligaments are inside the joint capsule
ACL and PCL
list the 3 structures involved in a terrible triad injury
ACL, MCL, and medial meniscus
which 2 ligaments are outside the joint capsule
MCL and LCL
is the knee a true 'hinge joint'?
No. It has accessory rotational components. The small amount of rotation present at end-range extension is the only thing that prevents the knee from being a true hinge joint
A snowboarder catches an edge and falls. His board twists in one direction as his body twists in the opposite direction. What is the most likely type of force experienced at the knee?
Rotary
explain how arthrokinematic motion of the knee and the cruciate ligaments of the knee work together
The ACL limits anterior slide of the femur on tibia. The PCL limits posterior slide of femur on tibia. MCL limits valgus position. LCL limits varus position.
What is the "Q-angle"? Why is it important?
The Q angle is formed by the intersection of the line between the tibial tuberosity and middle of the patella and the line between the ASIS and the middle of the patella. The greater the angle, the higher the stress on the patellofemoral joint during knee flexion and extension.
pes anserine
common location of bursitis and tendonitis as there is a bursa directly the 3 tendons that insert here
A clinician is applying force to the lower leg of a patient who is trying to extend the knee. Can the clinician apply more to the patient's leg by pushing down just below the knee or just above the ankle? Why?
The clinician can apply greater force just above the ankle than just below the knee because the force lever arm is longer. The axis is the knee joint. The resistance is being applied by the patient in this case. The resistance arm is the distance between the axis and the insertion of the quadriceps muscle, which does not change. The force arm is the distance between the axis and the plane on the patient's leg where force is applied. Stated another way, the clinician does not need to apply as much force when using a linger force lever arm as she would with a shorter force lever arm to accomplish the same result.
What is the pes anserine?
The distal attachments of the sartorius, gracilis, and semitendinosus muscles.
is the proximal tibia convex or concave
concave
In the open chain: a. The tibia rotates in a (an) ___ direction during the last few degree of knee extension. b. This happens because the ___femoral condyle is shorter and runs out of articular surface before the tibia reaches full extension. c. If this extension was happening in the closed chain, rather than seeing tibial rotation, the femur would instead rotate in a (an) ___ direction.
a. lateral b. lateral c. medial
what is the Q-angle?
angle between the quadriceps muscle and patellar tendon
what motion does the ACL limit
anterior motion of the tibia on femur
with arthritis, what tissue breaks down
articular cartilage of the distal femur and proximal tibia
explain the 'screw home mechanism
as extension occurs in weight bearing, the lateral articulation surface is used up. the medial femur glides posteriorly during the last few degrees of extension causing the femur to rotate medially on the tibia
extension ROM
as femur rolls it will also glide posteriorly on tibia
lateral collateral ligament (LCL)
attached to lateral condyle of femur and runs down head of fibula; no attachment to lateral meniscus; strong, not commonly injured; limits varus position
medial collateral ligament (MCL)
attaches medial condyles of tibia and femur; limits valgus position; fibers of medial meniscus are attached here; tighten during extension, slack during flexion
prepatellar bursae
between skin and patella
deep infrapatellar bursa
between tibial and patellar tendon
infrapatellar (subcutaneous) bursa
between tibial tuberosity and skin
which of the 3 hamstring muscles inserts on the lateral side of the knee?
biceps femoris
Closed chain - screw home mechanism
during last few degrees of extension, femur will rotate medially on tibia
Open chain - screw home mechanism
during last few degrees of extension, tibia will rotate laterally on femur
at what point through knee ROM does the screw home mechanism occur?
during the last 3 degrees of extension
soft tissue approximation
end feel of knee flexion; contact between muscle bellies of leg and thigh
soft tissue stretch
end-feel at knee extension; tension of joint capsule and ligaments