Kinesiology Lab: Lower Extremity Mechanics

<p>20-30º (D)</p> Signup and view all the answers

<p>4-6 degrees (B)</p> Signup and view all the answers

<p>9-12º (C)</p> Signup and view all the answers

<p>Pronation (A)</p> Signup and view all the answers

<p>The leg is in a neutral position (B)</p> Signup and view all the answers

<p>Firm (B)</p> Signup and view all the answers

<p>It results in medial rotation at the left hip. (B)</p> Signup and view all the answers

<p>Push-off (B)</p> Signup and view all the answers

<p>Inversion &gt; Eversion (B)</p> Signup and view all the answers

<p>Neutral position (C)</p> Signup and view all the answers

<p>Weakness in the gluteus medius muscle (C)</p> Signup and view all the answers

<p>To create a lever effect that counters weight on the weak hip (D)</p> Signup and view all the answers

<p>Decreased moment arm for hip abductors (B)</p> Signup and view all the answers

<p>Yes, it reduces risk of dislocation (D)</p> Signup and view all the answers

<p>It results in increased activation on the opposite side (C)</p> Signup and view all the answers

<p>It shifts medially, increasing force on the medial knee (A)</p> Signup and view all the answers

<p>It controls valgus motion and stabilizes the joint (B)</p> Signup and view all the answers

<p>Increased compressive JRFs and delayed knee flexion. (D)</p> Signup and view all the answers

<p>Equally between the medial and lateral condyles (C)</p> Signup and view all the answers

<p>Patella baja (A)</p> Signup and view all the answers

<p>10-15° (C)</p> Signup and view all the answers

<p>Abduction and eversion. (A)</p> Signup and view all the answers

<p>Medial rotation of the tibia and fibula. (D)</p> Signup and view all the answers

<p>5-10° (B)</p> Signup and view all the answers

<p>Inclined 14° in the transverse plane. (B)</p> Signup and view all the answers

<p>Creates a posteriorly directed vector of force. (D)</p> Signup and view all the answers

<p>Assists in posterior tibial translation (D)</p> Signup and view all the answers

<p>Hamstrings (B)</p> Signup and view all the answers

<p>45-60° (C)</p> Signup and view all the answers

<p>Causes anterior tibial translation (D)</p> Signup and view all the answers

<p>It allows for balanced muscle force interactions. (B)</p> Signup and view all the answers

<p>Increases the moment arm (C)</p> Signup and view all the answers

<p>It is weakest. (A)</p> Signup and view all the answers

<p>Increase in compressive joint reaction forces (D)</p> Signup and view all the answers

<p>5/6 of the body weight (C)</p> Signup and view all the answers

<p>It causes right adduction moment on the left hip. (B), It causes left adduction moment on the right hip. (C)</p> Signup and view all the answers

<p>They provide a counteracting moment. (C)</p> Signup and view all the answers

<p>Force and moment arm. (D)</p> Signup and view all the answers

<p>To reduce the moment arm and decrease stress on the hip. (D)</p> Signup and view all the answers

<p>The femoral head experiences increased compressive force. (A)</p> Signup and view all the answers

<p>By multiplying hip abductor force by MA. (A)</p> Signup and view all the answers

A diarthrosis joint, specifically planar, allowing gliding motions.

One degree of freedom (DF-PF), meaning primarily dorsiflexion (DF) then plantarflexion (PF).

Allows inversion and eversion. Doesn't have major active range of motion (ROM).

Maximum dorsiflexion (DF)

Contributes to pronation and supination during walking with inversion and eversion.

4-6 degrees of inversion (INV) and eversion (EV) during walking, resulting in a total range of 9-12 degrees.

A firm end-feel during inversion due to tension in the lateral collateral ligament, evertors talocalcaneal ligaments, and lateral joint capsule.

A firm/hard end-feel during eversion due to contact between the talus and calcaneus, plus tension in medial structures.

Inversion (INV) has greater limitation than eversion (EV) in the subtalar joint.

Supination (combination of talocrural DF, subtalar INV/ADD, and foot adduction).

Pronation (combination of talocrural DF, subtalar EV/ABD, and foot abduction).

Slight supination with lower extremity in external rotation (ER) during heel strike in gait.

Increasing supination and external rotation (hip and knee locking) during push-off phase of gait.

The perpendicular distance between the line of action of a force and the axis of rotation.

The force of gravity acting on the body's mass, creating a rotational effect around a joint.

The HAT's weight creates an adduction moment around the weightbearing hip, tending to drop the pelvis on the opposite side.

Hip abductor muscles counteract the adduction moment of the HAT, stabilizing the pelvis and preventing it from dropping on the unsupported side.

The force exerted by the hip abductor muscles and the weight of the body, acting on the femoral head during unilateral stance.

A walking pattern where the trunk leans over the painful hip during single leg stance, reducing the load on the injured joint.

Antalgic gait reduces the adduction moment on the painful hip by shifting the body's weight more directly over the joint, relieving stress.

By reducing the adduction moment and the compression force on the painful hip, antalgic gait minimizes pain and allows for easier movement.

A gait characterized by a drop of the pelvis on the side opposite the weak hip abductor muscles, typically caused by weakness or damage to the gluteus medius.

When using a cane for pain relief in hip problems, the cane should be held on the side opposite the affected hip. This reduces stress on the painful joint and improves balance.

Changing the angle of inclination (coxa valga or vara) impacts hip abductor muscle efficiency. Coxa valga increases the moment arm, making abduction easier, while coxa vara reduces the moment arm, requiring more effort.

In hip replacements, placing the femoral neck in coxa vara (smaller angle) can be beneficial by reducing stress on the femoral head and potentially improving stability.

Weakness in hip abductors can lead to increased activation of the quadratus lumborum on the opposite side, potentially causing muscle shortening and tightness.

In relaxed standing, weight is distributed equally between the medial and lateral condyles of the knee. During dynamic activities, the mechanical axis shifts medially, increasing medial compressive forces.

The MCL's tension during knee valgus movement generates a laterally directed component of the joint reaction force, helping stabilize the joint.

The tibiofemoral joint has a limited arc of motion on its medial compartment due to the strong restraint of the axis of rotation.

Due to the medial shift of the mechanical axis during dynamic activities, the medial side of the knee experiences higher compressive forces. This can contribute to osteoarthritis if not managed properly.

During weight-bearing, concentric soleus contraction causes posterior tibial translation, which helps stabilize the ACL.

In weight-bearing, concentric hamstring contraction causes posterior tibial translation, further assisting ACL stability, especially during greater knee flexion.

During weight-bearing, concentric gastrocnemius contraction results in anterior tibial translation or posterior femoral translation, aiding PCL stability.

An isolated quadriceps concentric contraction in full knee extension creates anterior tibial translation, putting increased strain on the ACL.

Co-activation of hamstrings and quadriceps during knee flexion, particularly ≥60°, helps reduce ACL strain by countering the anterior tibial translation caused by the quadriceps.

The patella increases the mechanical advantage of the quadriceps muscle during knee extension.

The quadriceps generates its maximum force, or moment, between 45-60° of knee flexion.

The patella is most functionally significant at 15° of flexion (near full extension) where the quadriceps' ability to generate a moment of force on the tibia is minimal.

A condition where the patella sits higher than normal on the femur, increasing the distance between the patella and the femoral groove. This alters the mechanics of the patellofemoral joint, affecting the forces and movements during knee flexion and extension.

A condition where the patella sits lower than normal on the femur, decreasing the distance between the patella and the femoral groove. This alters the mechanics of the patellofemoral joint, affecting the forces and movements during knee flexion and extension.

The angle formed between the quadriceps muscle and the patellar tendon, indicating the alignment of the femur and tibia. A normal Q-angle is 10-15 degrees. Deviation from this range can affect patellofemoral joint mechanics and increase stress on the patella.

The Vastus Lateralis (VL) and Vastus Medialis (VM) muscles contribute to knee extension and also exert a posterior force that increases the compressive force on the patellofemoral joint, even during knee extension.

The axis of rotation of the talocrural joint (ankle) is not a straight line but is slanted at 14° in the transverse plane and 23° in the frontal plane. This oblique axis allows for coupled motions in all three planes of motion during ankle movements.

During dorsiflexion (DF) of the ankle, the talus moves slightly laterally (abduction) and the foot everts (medial tilt).

During plantarflexion (PF) of the ankle, the talus moves slightly medially (adduction) and the foot inverts (lateral tilt).

During dorsiflexion (DF) in a closed kinetic chain (CKC), the tibia rotates medially on the talus.