Knee Flashcards
What are the 2 joints of the knee?
- Tibiofemoral joint
- Patellafemoral joint
What are the 3 most common types of knee injuries seen clinically?
- Unspecified sprains, strains or overuse injuries
- Contusions
- Meniscal or ligamentous injuries
Which knee joint is the largest joint in the body?
the tibiofemoral joint
The tibiofemoral joint has _ degrees of freedom, what are they?
3:
Flexion/Extension
Internal Rotation/External Rotation
Abduction/Adduction
The lateral condyle serves as the origin of what 3 structures?
- Popliteus
- Lateral head of the gastrocnemius
- Lateral collateral ligament (LCL)
The medial condyle serves as the origin of what 3 structures?
- Adductor magnus
- Medial head of the gastrocnemius
- Medial collateral ligament (MCL)
Tibial plateaus are con___ in the mediolateral direction
concave
The medial tibial plateau is con___ in the A/P direction
concave
The lateral tibial plateau is con___ in the A/P direction
convex
Does the medial or lateral tibial plateau have a larger surface area? How much larger is it?
The medial plateau has a surface area that is approximately 50% greater than that of the lateral plateau
Medial plateau’s articular surface is __ times thicker than the lateral plateau’s
3
The presence of what accentuates the concavity of the tibial plateaus?
the menisci
What is the resting position of the tibiofemoral joint?
25 degrees of flexion
What is the closed-packed position of the tibiofemoral joint?
Full Extension and External Rotation of the Tibia
What is the capsular pattern for the tibiofemoral joint?
Flexion > Extension
What type of joint is the patellofemoral joint?
Modified plane joint
The patella has _ facets. What are they?
5: Odd Superior Inferior Medial Lateral
Which patellar facet is most frequently affected with chondromalacia patella?
the odd facet
What are the 5 functions of the patellofemoral joint?
- Provide the articulation with low friction
- Protect the distal aspect of the femur from trauma and the quadriceps from attritional wear
- Improve the cosmetic appearance of the knee
- Improve the moment arm (distance between the center of gravity and the center of rotation) of the quadriceps
- Decrease the amount of A/P tibiofemoral shear stress placed on the joint
Describe the positioning of the knee joint capsule in reference to the patella. What does it form?
The capsule ascends superiorly/anteriorly above the patella to form the suprapatellar pouch
What lines the inner portion of the knee joint capsule?
synovial membrane
What does the synovial membrane exclude from the interior portion of the knee joint?
the cruciate ligaments
The cruciate ligaments are ___-synovial and ___-articular
extrasynovial and intra-articular
What type of the joint is the proximal tibiofemoral joint?
Plane synovial joint between the Tibia and the Fibular Head
Which aspects of the proximal tibiofibular joint are convex and which are concave?
There is a slight convexity on the oval tibial facet and a slight concavity of the fibular head
In what direction does the tibial facet at the proximal tibiofemoral joint face?
laterally, posteriorly, and inferiorly
Does the proximal or distal tibiofemoral joint have more motion?
proximal
What are the 2 glides that can occur at the proximal tibiofemoral joint?
- Superoinferior direction
- Anteroposterior direction
The ACL is the primary restraint for which motions?
Anterior translation and medial rotation of the tibia on the femur
The PCL is the primary restraint for which motions?
Posterior translation and medial rotation of the tibia on the femur
Both the ACL and PCL are the secondary restraints for which motions?
Valgus and varus rotation of the tibia
The MCL is the primary restraint for which motions?
Valgus and lateral rotation of the tibia
The LCL is the primary restraint for which motions?
Varus and lateral rotation of the tibia
Both the MCL and LCL are the secondary restraints for which motions?
anterior and posterior translation of the tibia on the femur
The ACL and PCL contain mechanoreceptors, so if there is disruption of these ligaments what happens?
There can be an interruption or elimination of sensory nerve fibers in the joint
The ACL’s ability to adjust to internal stress influences what 3 things?
- laxity of the joint
- stresses of the joint
- kinematics of the joint
Which knee ligament is the strongest?
the PCL
It is twice as strong as the ACL, MCL, and LCL
Forcing the ACL more than _% beyond its resting length may result in rupture.
5
The PCL provides __-__% of the total restraint to posterior translation of the tibia on the femur
90 - 95%
Are the MCL and LCL extra- or intra-articular ligaments
extra-articular ligaments
Describe the structure of the MCL
It develops as a thickening of the medial joint capsule and is subdivided into a superficial band and a deep band
Describe the superficial band of the MCL
It is a thick, flat band that has a fan-like attachment proximally on the medial femoral condyle and blends with the posteromedial corner of the capsule
Describe the deep band of the MCL
It is a continuation of the capsule that blends with the Medial Meniscus
Which part of which ligament is the first to be injured when a valgus stress is applied
Superficial band of the MCL
Where does the LCL originate and insert at?
It arises from the lateral femoral condyle and runs distally and posteriorly to insert onto the head of the fibula
Does the LCL blend with the lateral meniscus?
No it develops independently, and remains completely free from the joint capsule and the lateral meniscus
The secondary knee restraints include structures in what aspects of the knee?
the posterolateral and posteromedial corners of the knee
What do secondary knee restraints serve to control?
anterior tibial translation relative to the femur
What provides dynamic stability to the knee?
Unopposed contraction of the quadriceps complex
What does the unopposed contraction of the quadriceps complex increase? And what is it synergistic to?
anterior tibial translation and is synergistic to the PCL
What does the unopposed contraction of the hamstrings complex increase? And what is it synergistic to?
posterior tibial translation and is synergistic to the ACL
What are 4 other structures that provide support to the knee?
- Popliteus
- Patellar Tendon
- Oblique popliteal ligament
- Fabella
What aspect of the menisci are more prone to tear with trauma?
the inner (thinner) regions
The outer __% of the lateral meniscus is vascularized
25%
The outer __% of the medial meniscus is vascularized
30%
What shape is the medial meniscus? What does this result in?
Semilunar (half circle)
Results in a wider separation of its anterior and posterior horns
How does the medial meniscus attach to the tibial plateau?
by coronary ligaments
What does the MCL also attach to?
to the deeper portion of the MCL and the knee joint capsule
What shape is the medial meniscus?
C-shaped
The lateral meniscus has an excursion of approximately __ mm, whereas the medial meniscus has an excursion of approximately __ mm.
10
2
Which menisci is larger and thicker?
medial
What are the 6 functions of the menisci?
- Load Transmission
- Shock Absorption
- Joint Lubrication
- Nutrition
- Secondary Mechanical Stability
- Guiding of Movements
List the 8 bursae of the knee
- Superficial Infrapatellar Bursa
- Deep Infrapatellar Bursa
- Prepatellar Bursa
- Tibiofemoral Bursa
- LCL Bursa
- Inferior Subtenindous Bursa (Biceps Femoris Tendon)
- Anserine Bursa
- Semimembranosus Bursa
What is a plica?
a remnant of the 3 cavities in the synovial mesenchyme of the developing knee
What is the retinacula formed from?
structures in the first and second layers of the knee joint
In summary, because the bony surfaces of the knee lend little to inherent stability, what is joint stability reliant on?
The restraints of:
- joint capsule - ligaments - menisci - musculature
During flexion of the knee, the femur rolls ____ and glides ______.
posteriorly
anteriorly
During extension of the knee, the femur rolls ____ and glides ______.
anteriorly
posteriorly
When are the lateral condyle of the femur and the lateral meniscus congruent?
From 30 - 5 degrees of WB knee extension
What does the lateral shift of the axis of movement during weight-bearing knee extension produce?
Internal rotation of the femur
What movement is the only one to accompany extension in the last 5 degrees of extension? What is this referred to as?
rotation
The “screw home mechanism”
During the “screw home mechanism” the tibia ______ rotates and the femur _______ rotates as the knee approaches full extension
externally
internally
Knee hyperextension is usually available from _ - _ degrees
0 - 15
During knee hyperextension, the femur tilts _____. What does this create?
forward
This creates anterior compression between the femur and the tibia
The Q angle is an angle formed by the bisection of what 2 lines?
- ASIS to the center of the patella
- Center of the patella to the tibial tubercle
What is the Q angle a measure of?
The tendency of the patella to move laterally when the quadriceps muscles are contracted
What is the normal Q angle for males? Females?
- 8–14 degrees for males
- 15–17 degrees for females
A Q angle greater than __ degrees is considered abnormal. What is this indicative of?
20
potential displacement of the patella
The Patellofemoral Joint Reaction Force is a function of what 2 things?
- Quadriceps and patellar tendon tension
- Angle formed between the quadriceps and patellar tendon
During OKC exercises, maximum patellofemoral joint reaction force in the quad/patellar tendon is generated when?
going from 90 degrees to full extension
During OKC exercises, the lowest patellofemoral joint reaction force in the quad/patellar tendon is generated when?
at 90 - 40 degrees
During CKC exercises, maximum patellofemoral joint reaction force in the quad/patellar tendon is generated when?
at 60 degrees
CKC exercises should initially be prescribe at _ - _ degrees and then can progress to _ - _ degrees
0 - 16
0 - 30
Describe patellar tracking in the normal knee
the patella glides inferiorly and superiorly during flexion and extension
The patella tracks _ - _ cm with respect to the femur during flexion and extension
5 - 7cm
The patella moves in a ____ C-shaped curve from 20 to 30 degrees of motion
lateral
Between 45 to 15 degrees the lateral curvature produces what 2 things?
- Gradual medial glide of the patella
- Medial tilt of the patella
Between 15 to 0 degrees the lateral curvature produces what 2 things?
- Lateral glide of the patella
- Lateral tile of the patella
What are 4 abnormal patellar tracking patterns?
- Medial tracking patella
- Lateral tracking patella
- Patella Alta
- Patella Baja
What is the Waldron test used to assess?
patellofemoral function
A posterior glide of the tibia on the femur increase _____.
flexion
An anterior glide of the tibia on the femur increase _____.
extension
Describe the 3 grades of a valgus and varus stress test
- Grade I: The joint space opening is within 2mm of the contralateral side
- Grade II: The joint space opens 3-5mm more than the contralateral side in 20 degrees of knee flexion and less than 2mm more than the normal knee in full extension
- Grade III: The joint space opens 5-10mm more than that of the normal knee in 20 degrees of flexion and full extension
What 2 tests assess for ACL tear?
- Lachman’s Test
- Anterior Drawer Test
How is Lachman’s test graded?
o 1+ (mild): 5mm or less
o 2+ (moderate): 5-10mm
o 3+ (serious): more than 10mm
What 2 tests assess for PCL tear?
- Posterior Sag (Godfrey) Sign
- Posterior Drawer Test
What is the pivot shift?
The anterior subluxation of the lateral tibial plateau that occurs when the lower leg is stabilized in (almost) full extension, whereby further flexion produces a palpable spring-like reduction
What 2 tests assess for the pivot shift?
- Subluxation Test
- Reduction Test
What patient position must patellar stability tests be assessed in?
90 degrees of flexion
What does a patellar glide determine?
the amount of lateral deviation of the patella in the frontal plane
A 5mm lateral displacement of the patella causes a __% decrease in VMO tension
50%
Patella can be passively displaced medially and laterally approximately _ cm, which is 1/_ the width of the patella
1 cm
1/3
What is considered abnormal patellar displacement?
more than 1/2 the patella over the medial or lateral aspect
What may cause a decrease in the medial glide of the patella?
IT Band and/or lateral retinaculum tightness
A slight ____ tilt of the patella is normal.
lateral
What does a medial tilt result from?
a tight lateral retinaculum
If the inferior pole of the patella is sitting lateral to the long axis of the femur, the patient has an _______ rotated patella
externally
If the inferior pole of the patella is sitting medial to the long axis of the femur, the patient has an _______ rotated patella
internally
What are the 6 meniscal tear tests?
- McMurray’s Test
- Apley’s Test
- Anderson Mediolateral Grind Test
- Bounce Home Test
- Figure-4 Test
- Payr Sign
When performing McMurray’s test how does the clinician test the integrity of the medial meniscus?
ER the tibia while slowly extending the knee
When performing McMurray’s test how does the clinician test the integrity of the lateral meniscus?
ER the tibia while slowly extending the knee
What is indicative of a positive test for a rotation sprain of the soft tissue when performing Apley’s test?
Pain upon distraction and IR and ER rotation of the tibia
What is indicative of a positive test for a meniscal tear when performing Apley’s test?
Pain upon compression while IR and IR the tibia
When performing the Anderson mediolateral grind test a ____ stress should be applied while the knee is flexed and a ____ stress should be applied while the knee is flexed
valgus
varus
Which meniscus test assess for a lateral meniscus tear? Medial meniscus tear?
Figure-4 Test
Payr Sign
What are the 4 characteristics of plical irritation?
- Anterior pain in the knee
- Painful clicking
- Giving way
- Catching
What are the 2 tests that assess for patellar chondromalacia?
- Zohler’s Sign
- Clarke’s Test
