Knee Flashcards
What type of joint is the Tibiofemoral joint?
The Tibiofemoral joint is a modified hinge joint (synovial) that allows primarily biaxial movement in one plane, including flexion, extension, and internal/external rotation.
What bones form the Tibiofemoral joint?
The Tibiofemoral joint is formed by the distal femur and proximal tibia.
Describe the static stabilizers of the Tibiofemoral joint.
• Joint capsule
• Menisci: Increases articular congruency, absorbs shock; the medial meniscus is attached to the medial joint capsule, MCL, and ACL.
• Patellar ligaments
• ACL/PCL: Provides anteroposterior stability.
• MCL/LCL: Provides mediolateral stability.
• ITB
What are the dynamic stabilizers of the Tibiofemoral joint?
• Pes anserinus (medial)
• Biceps femoris and semimembranosus (posterior)
• Gastrocnemius (posterior)
• Popliteus (posterior)
• Quadriceps and extensor retinaculum (anterior)
What type of joint is the Patellofemoral joint?
The Patellofemoral joint is a plane (synovial) joint that allows gliding between the femur and patella.
What bones form the Patellofemoral joint?
The Patellofemoral joint is formed by the distal femur and the patella.
What is unique about the patella in terms of bone classification?
The patella is the largest sesamoid bone in the body.
How does the patella increase the biomechanical advantage of the quadriceps?
The patella enhances the quadriceps’ biomechanical advantage during the last 30 degrees of knee extension and redirects forces exerted by the quads.
How does the patella track during knee movement?
The patella tracks laterally during extension, following the line of pull of the quadriceps.
What is the normal range of motion (ROM) for knee flexion?
Flexion = 135 degrees.
What is the normal range of motion (ROM) for knee extension?
Extension = 0 degrees.
What is the normal range of motion (ROM) for knee internal rotation?
Internal Rotation = 30-40 degrees.
What is the normal range of motion (ROM) for knee external rotation?
External Rotation = 20-30 degrees.
Why do we need a balance of stability and mobility in the human body?
To achieve mechanical efficiency in movement.
What determines the primary need of a joint (stability vs. mobility)?
Available movement at the joint, articulation, amount of static and muscular stabilizers, etc.
Do two joints with the same primary need (stability or mobility) usually appear in tandem?
No, typically two joints with the same primary need are not found in tandem.
What happens if a joint lacks stability or mobility?
Another joint will compensate, leading to mechanical inefficiency and potential injury.
What is the primary functional need of the knee?
Stability, due to its sagittal plane movement, poor articulation, and vulnerable static stabilizers.
What planes of motion must be controlled for efficient knee movement in the sagittal plane?
Rotation and abduction/adduction must be controlled.
How does knee instability manifest?
As unwanted movement in the transverse and/or coronal planes while trying to move in the sagittal plane.
What are the knee’s menisci and ligaments sensitive to?
Varus/valgus forces and shear stress, making stability important to prevent injury.
What can cause excessive rotation or adduction/abduction in the knee?
Issues at neighboring joints, such as excessive pronation/supination at the subtalar joint or lack of pelvic stability.
How does excessive pronation at the subtalar joint affect the knee?
It can lead to compensatory movement in the knee, increasing stress and instability.
What effect does pelvic instability have on the knee?
It may cause compensatory adduction or internal rotation in the knee, leading to valgus stress.
During single limb stance in gait, which directions does gravity pull the hip/pelvis?
Into adduction and internal rotation.
Which muscles control adduction and internal rotation at the hip during single limb stance?
The deep lateral rotators (control internal rotation) and hip abductors (gluteus medius controls adduction).
What are possible consequences of weakness in gluteus medius or deep lateral hip rotators?
Valgus at the knee and overpronation at the subtalar joint due to increased adduction/internal rotation.
How does overpronation (pes planus) of the ankle affect the lower extremity and knee?
Causes internal rotation of the lower extremity, dysfunctional patellar tracking, and valgus at the knee.
What are the effects of oversupination (pes cavus) of the ankle on the lower extremity and knee?
Leads to external rotation of the lower extremity, strain on lateral structures, potential varus at the knee, and hyperextension with excessive tibial external rotation.
How do weak hip lateral rotators and abductors impact the lower extremity?
They cause internal rotation in the lower extremity, which may lead to overpronation of the foot.
What effect does femoral anteversion have on the knee?
It can increase the Q angle and cause lateral patellar tracking issues.
How does an increased Q angle impact patellar movement?
It may lead to patellar tracking issues, especially laterally.
What are the key ankle and foot observations for a quick postural assessment related to knee pain?
Look for pes planus (overpronation), pes cavus (oversupination), and toe-out/in positioning.
What are the implications of pes planus in a postural assessment?
Overpronation can cause medial tibial rotation, valgus at the knee, patellar tracking issues, and inefficient force distribution up the kinetic chain.
How does pes cavus affect the lower extremity during weight-bearing?
It leads to lateral tibial rotation, possible patellar tracking issues, and fails to dissipate forces effectively.
What does a toe-in or toe-out position indicate in a knee pain assessment?
It may suggest tibial or femoral rotation.
What are important knee observations in a postural assessment for knee pain?
Check for tibial rotation, patellar height, varus/valgus alignment, and hyperextension.
What are the implications of medial and lateral tibial rotation on knee function?
Medial rotation often accompanies overpronation, and lateral rotation accompanies oversupination, both affecting patellar tracking.
How does varus or valgus alignment impact the knee?
It stresses the collateral ligaments and joint capsule.
What is the implication of hyperextension at the knee?
Hyperextension places stress on the ACL.
What hip observations are critical in a knee pain assessment?
Observe for innominate rotation, increased Q angle, and femoral retroversion or anteversion.
How does innominate rotation or a leg length discrepancy affect the knee?
The longer leg may overpronate to compensate, leading to tibial rotation and valgus stress at the knee.
What is the impact of an increased Q angle on the knee?
It increases the bowstring effect on the quadriceps, causing more lateral patellar tracking.
What are the implications of femoral anteversion in knee assessments?
Femoral anteversion can increase the Q angle and may indicate muscular imbalances at the hip.
What is the Q angle?
The Q angle is the angle formed by two intersecting lines: one from the ASIS to the midpoint of the patella, and the other from the tibial tuberosity to the midpoint of the patella.
What do the two lines of the Q angle represent?
They represent the bowstring effect on the patella from the pull of the quadriceps femoris muscle and the patellar tendon.
What is considered a normal Q angle?
A normal Q angle is 10-15 degrees, typically greater in females than in males.
Where does the patella typically stay and track with a normal Q angle?
The patella stays and tracks within the intercondylar groove.
What factors help maintain a normal alignment of the patella?
- Balanced pull of the vastus medialis (VMO) and vastus lateralis
- The lateral condyle of the femur projecting more anteriorly
- Medial and lateral patellofemoral ligaments
What factors can increase the Q angle?
• A wide pelvis
• Changes in the orientation of the femur and tibia relative to each other
• Genu valgus
What are the impacts of an increased Q angle on the knee?
• Increased lateral tracking of the patella
• Increased patellofemoral pressure, especially the • lateral facet against the lateral femoral condyle during flexion and weight-bearing
What is neuromuscular inhibition?
Neuromuscular inhibition occurs when muscles do not function optimally and may test weak due to neurological inhibition.
What are common causes of neuromuscular inhibition?
• Pain
• Inflammation
• Trigger points
• Myofascial restrictions
• Joint effusion
• Joint laxity
• Reciprocal inhibition (short antagonist)
• Nerve impingement or damage
• Disuse or deconditioning
How does the CNS respond to tissue damage or joint issues?
The CNS may inhibit muscle function via motor nerves to protect tissue from further injury.
How can a short or overused muscle affect its antagonist?
A short or overused (hyper-facilitated) muscle can inhibit its antagonist, a process known as reciprocal inhibition.
What is reciprocal inhibition?
Reciprocal inhibition is when a hyper-facilitated muscle causes inhibition in its opposing muscle (antagonist).
How does injury impact muscle balance?
An inhibited muscle after injury may leave its antagonist unopposed, potentially causing hyper-facilitation in the antagonist.
Why is rehabilitation important after injury in relation to muscle control?
Rehabilitation is necessary to restore proper muscular control and synergy, allowing both agonist and antagonist muscles to function correctly.
What is meant by “flexion dominance” in human biology?
Humans are biologically flexion dominant; our primary spinal curve is kyphotic, and we develop secondary curves (lordosis) through muscular effort to achieve an erect posture.
What is the function of the popliteus muscle?
The popliteus muscle:
• Unlocks the knee from an extended position via tibiofemoral rotation to allow knee flexion
• Stabilizes the posterior knee
• Protects the knee from excessive flexion, anterior femoral translation, and posterior tibial translation
What are the attachments of the popliteus muscle?
The popliteus attaches from the lateral femoral condyle to the medial aspect of the proximal tibia, with additional connections to the fibular head, PCL, and lateral meniscus (with some variation between individuals).
How does the popliteus muscle compare to knee ligaments in its stabilizing function?
Similar to certain knee ligaments, the popliteus muscle stabilizes the posterior knee and protects it from excessive flexion and anterior femoral translation.
What is the “screw home mechanism”?
The screw home mechanism is a process where the tibiofemoral joint locks in extension, which:
• Reduces the workload on the quadriceps
• Provides maximal stability for an upright posture