Biomechanics of TF joint

Practice vocabulary flashcards covering the anatomical components, kinematics, arthrokinematics, alignment, and stabilizing structures of the tibiofemoral joint.

Tibiofemoral Joint

The largest synovial joint in the body, which connects the two longest lever arms and transmits forces equal to $2\text{--}5$ times body weight during daily activities.

Medial Femoral Condyle

A convex condyle of the distal femur that projects more distally than the lateral condyle to account for the anatomical slope of the femur.

Medial Tibial Plateau

The larger and slightly concave proximal articulation surface of the tibia that accepts the medial femoral condyle.

Lateral Tibial Plateau

The smaller, flat or slightly convex proximal articulation surface of the tibia that accepts the lateral femoral condyle.

Instantaneous Center/Axis of Rotation

The continually migrating axis of rotation during knee flexion and extension that lines up with the femoral epicondyles.

Closed-chain Knee Extension

An arthrokinematic movement on a fixed tibia where the femoral condyles roll anteriorly and slide posteriorly.

Closed-chain Knee Flexion

An arthrokinematic movement on a fixed tibia where the femoral condyles roll posteriorly and slide anteriorly.

Open-chain Knee Extension

An arthrokinematic movement on a fixed femur where the tibial plateaus roll anteriorly and slide anteriorly.

Open-chain Knee Flexion

An arthrokinematic movement on a fixed femur where the tibial plateaus roll posteriorly and slide posteriorly.

Close-packed Position of the Knee

The position of full knee extension characterized by maximal bony congruence and maximal ligamentous tautness.

Loose-packed Position of the Knee

A position at approximately $25^\times$ of knee flexion characterized by minimal bony congruence, lax ligaments, and minimal intra-articular pressure.

Screw-home Mechanism

The coupling of full knee extension with external knee rotation during the final $20^\times$ of extension to maximize structural stability and minimize muscle effort during standing.

Popliteus Muscle

The muscle that unlocks the knee from full extension by internally rotating the tibia relative to the femur.

Normal Genu Valgum

The normal frontal plane alignment of the knee, which measures approximately $170^\times\text{--}175^\times$.

Excessive Genu Valgum

A frontal plane deviation (knock-knee) where the alignment angle is less than or equal to approximately $165^\times$.

Genu Varum

A frontal plane deviation (bow-leg) where the alignment angle is greater than or equal to approximately $180^\times$.

Load-bearing Axis (LBA)

A line extending from the center of the femoral head through the knee center to the center of the ankle, along which ground reaction forces pass without creating external joint moments.

Red Zone of the Meniscus

The vascularized outer third region of the meniscus that possesses a direct blood supply essential for tissue healing.

Anteromedial Bundle of the ACL

The smaller bundle of the anterior cruciate ligament that becomes tighter with greater degrees of knee flexion.

Posterolateral Bundle of the ACL

The larger bundle of the anterior cruciate ligament that becomes tighter with greater degrees of knee extension.

Anterolateral Band of the PCL

The structural band of the posterior cruciate ligament that becomes tight during knee flexion.

Posteromedial Band of the PCL

The structural band of the posterior cruciate ligament that becomes taut during knee extension.

Medial Collateral Ligament (MCL)

A two-layer joint stabilizer with a force to failure of approximately $800\text{ N}$ that resists external valgus forces, hyperextension, rotation, and anterior tibial translation.

Lateral Collateral Ligament (LCL)

An extracapsular structure extending from the proximal femoral condyle to the fibular head with a force to failure of approximately $400\text{ N}$ that resists external varus forces.

Genu Recurvatum

Excessive hyperextension of the knee joint exceeding $10^\times$, primarily resisted by the posterior capsule and surrounding soft tissues.