Module 3 • 25 min
Tibiofemoral movement
Learn about the relationship between the structure of the femur & tibia and its complex movement.
Learning Objectives
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Describe the rolling and gliding motion of the tibia and femur and its relation to structure and function (covered previously in Module 2).
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Understand the complex 3D movement of the knee, where not only rolling & gliding occurs, but also internal and external rotation (otherwise known as the screw home mechanism).
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Note: it is recommended that you complete Modules 2 before diving into the more complex topics discussed below.
Section 3.1
Rolling and gliding
In large part, the complex movement of the TF joint is a function of its articular surfaces. By synthesizing the content discussed in Module 1 & Module 2, one can begin to appreciate the structures of the knee and their role in sustaining normal knee function.
The surface area of the femoral condyles is larger than the tibial side which indicates that a pure rolling motion would be impossible (as this would require equal articular surfaces). If pure rolling were to occur, the femur would simply roll off of the tibia (Figure 3.1). Therefore, as the knee is flexed past 20°, a combination of rolling & gliding occurs at the TF joint. During this time, the point of contact between the tibia and femur moves anteriorly during extension and posteriorly during flexion; a lower level of congruence in the lateral compartment of the knee leads to increased translation on the lateral side (see Figure 2.7). The rolling & gliding motion also causes the instant centre of rotation to move posteriorly during flexion and anteriorly during extension. Use the interactive slider below (Figure 3.1) to learn more about rolling & gliding; the slider to the right illustrates a hypothetical scenario where only rolling occurs at the knee joint (ultimately causing failure).
The nature of rolling and gliding changes between closed kinetic chain (CKC) and open kinetic chain (OKC) movements:
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In a CKC knee flexion, the femur rolls posteriorly and glides anteriorly on the tibia. For knee extension, the femur rolls anteriorly and glides posteriorly.
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In an OKC knee flexion, the tibia rolls and glides posteriorly. As for knee extension, the roll and glide are anterior.
The interactive visualization below (Figure 3.1) illustrates rolling and gliding in a CKC scenario (where the femur is the mobile bone).
Figure 3.1 - Rolling and gliding. Left: knee joint showing normal rolling and gliding movement. Right: hypothetical scenario where only rolling occurs, and leads to knee joint failure. CC BY-NC-ND 4.0
Note: This is an interactive visual. Drag the knob of the slider below to interact with the visualization.
Section 3.2
Screw home mechanism
In addition to rolling and gliding, a rotation of approximately 10 - 15° also takes place in the final few degrees of knee extension, known as the screw home mechanism. This rotation “locks” the knee joint in place, and serves as a stable orientation for the fully extended knee. In this position, the surrounding muscles are able to relax without compromising stability. When the knee flexes from the extended position, rotation must occur once more to release or “unlock” the knee. As one can imagine, the screw home mechanism is a result of the differences in size, shape, and orientation of the tibial plateaus and femoral condyles as discussed previously in Module 2 (Section 2.1).
The nature of the rotation changes between CKC and OKC movements. In a CKC exercise, the femur rotates externally and internally on the fixed tibia during knee flexion and extension, respectively. On the other hand, in an OKC movement, the tibia is now the mobile bone; as the knee is flexed and extended, the tibia rotates internally and externally, respectively. See Figure 3.2 below to learn more about the screw home mechanism.
Refer to Table 3.1 below for details regarding the rolling, gliding, and rotational movements that occur during both OCK and CKC scenarios.
Figure 3.2 - Screw home mechanism. Click the video to pause/play. CC BY-NC-ND 4.0
Table 3.1 - Summary of CKC & OCK movements. CC BY-NC-ND 4.0
Closed Kinetic Chain Movement (mobile femur on stationary tibia)
Type of movement
Roll
Glide
Rotation
Movement during flexion
Femur moves posteriorly on tibia
Femur moves anteriorly on tibia
Femur rotates externally on stationary tibia
(from full knee extension to 20° flexion)
Movement during extension
Femur moves anteriorly on tibia
Femur moves posteriorly on tibia
Femur rotates internally on stationary tibia
(from 20° flexion to full knee extension)
Open Kinetic Chain Movement (mobile tibia on stationary femur)
Type of movement
Roll
Glide
Rotation
Movement during flexion
Tibia moves posteriorly on femur
Tibia moves posteriorly on femur
Tibia rotates internally on stationary femur
(from full knee extension to 20° flexion)
Movement during extension
Tibia moves anteriorly on femur
Tibia moves anteriorly on femur
Tibia rotates externally on stationary femur
(from 20° flexion to full knee extension)
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Citing this page (APA) - Module 3 - Tibiofemoral movement. kneeMo. https://www.kneemo.ca/module-three