- What actions at the tibifemoral joint accompany flexion-extension of the tibia in relation to the femur? What accounts for these additional actions?
Flexion at The knee occurs with rolling lateral flexion and abduction of the femur and some translation
- True or false. The medial articular surfaces of the tibiofemoral joint have better congruency than the lateral articular surfaces
True
- What is the screw home mechanism of the knee? What are TWO potential causes?
1) To accommodate the larger surface of the medial femoral condyles
2) passive tension in both the ACL & PCL
3) slight lateral pull of the quadriceps muscle group
- Describe the movement pattern between the articular surfaces of the tibiofemoral joint when the tibia extends in relation to the femur? How about when the femur extends in relation to the tibia?
1) During flexion the tibia internally rotates in relation to the femur
2) during extension the tibia externally rotates in relation to the femur
* difference in the size and shape of the articular surfaces account for the internal-external rotation
- Whilst the menisci act to improve the congruence between the articular surfaces of the tibiofemoral joint, what is considered to be their primary function?
Reduces the compression stress on the articular cartilage
- True or false. The menisci move in association with movement between the articular surfaces of the tibiofemoral joint?
True. The menisci move in concert with the rolling femoral condyles
- Why is the medial meniscus injured more often than the lateral meniscus?
Because there is a Stronger attachment to the medial collateral ligament
- Which ligament provides the primary restraint against a valgus for acting on the knee complex?
Medial collateral ligament
- Which ligament provides the primary restraint against anterior translation of the tibia on the femur?
the anterior cruciate ligament limits anterior translation
- What is the primary function of the patella?
.increase the length of the moment arm of the quadriceps tendon
+although the patella protects the quadriceps tendon from excessive friction from the femur during knee flexion
- What articulation forms the patellofemoral joint?
Between the patella and the trochlear notch of the femur -gliding joint
- Describe how the patella moves during extension of the tibia in relation to the femur.
As the femur deviates laterally from the tibia contraction of these muscle pulls the patella proximally and laterally
- What causes the tendency for the patella to be displace laterally during extension of the tibia in relation to the femur?
The articulation of the patella
The line of action of the vastus lateralis is slightly lateral to the femur
When the femur deviates laterally from the tibia, the patella is pulled laterally by these muscles
- What is the Q angle and how is it measured?
Clinical measure that can be used to quantify the lateral deviation of the femur
***Formed between the a line drawn from the centre of the patella to the ASIS and a & a line drawn from the centre of the patella to the tibial tuberosity. Good is 10-20%.
- What are TWO measures that help to prevent the lateral deviation of the patella?
+The expanded surface of the lateral condyle of the femur acts as a buttress against lat disp
++a medially directed stabilising force provided by the oblique fibres of vastus medialis
- True or false. Genu recurvatum can increase the stress on the posterior joint capsule and ACL?
True-GENUINE RECURVATUM is hyper extension of knee. Results is increased stress on the posterior joint capsule and ACL
- Which muscles make up the pes anserinus (3)?
How do these muscles work together to dynamically stabilise the knee?
(3) insert….
SEMItendinosus, gracilis & sartorius
All insert close together on the medial aspect of the knee
All flex and IR knee
Work together against valgus and ext rotatory forces
- What is a key role of the politeus muscle during flexion of the tibiofemoral joint from a fully extended position?
Popliteus
-Rotates the femur externally to initiate femoral on tibial flexion or can rotate the tibia internally to initiate tibial on femoral flexion
- It is also an important dynamic stabilizer
- Reinforces the PCL
- Helps to prevent posterior translation of the tibia
- Supports the knee medially by controlling ER
- Its strong tendon helps to resist knee varus
- By creating tension in the iliotibial band, the contraction of which muscles helps to stabilise the lateral aspect of the knee?
TFL & Gluteus maximus
++It provides dynamic stability to the lateral aspect of the knee via its attachment to the ITB, increasing its activity when there are VARUS forces
++Tightness is associated with medial and lateral knee pain
- From a movement perspective what are two reasons why females may be more likely than males to incur an anterior cruciate ligament (ACL) injury when landing from a jump.
Land with more hip adduction & IR and more knee valgus
Land with less knee flexion and maintain a more extended knee during the stance phase
Higher quadriceps activation during the landing phase
What happens during femoral on tibial extension? Does the femur internally or externally rotate on the tibia?
When a person rises up from a squat position the knee locks into extension as the femur internally rotates relative to the fixed tibia
(Screw home mechanism)
From full extension the knee must ……. Rotate as flexion is initiated?
The knee must internally rotate as flexion is initiated
What bone has the thickest posterior articulating cartilage of any joint
The patella
Which two muscles are involved in positioning the patella?
Rectus femoral and vastus intermedius
