Lippert Ch. 19 Knee

Patella mobility during knee flexion/extension.

(A) with knee extended, patella can be moved side-to-side. (B) With knee flexed, side-to-side motion of patella is not possible.

Miserable malalignment syndrome

alignment problem of the lower extremity involving increased anteversion of the femoral head and is associated with genu valgus, increased tibial torsion, and a pronated flat foot.

Q angle, or patellofemoral angle

angle between the quadriceps muscle (primarily the rectus femoris muscle) and the patellar tendon line from the anterior superior iliac spine (ASIS) to the midpoint of the patella, and from the tibial tuberosity to the midpoint of the patella

patellofemoral pain syndrome

anterior knee pain. It is generally considered the result of a variety of alignment factors, such as increased Q angle

Prepatellar bursitis

epeated direct blows or sheering stresses on the knee from constant pressure

Anterior muscles ________ the knee, posterior muscles ________ the knee, and muscles crossing the medial and lateral sides help provide medial and lateral stability

extend, flex

end feel of knee extension

firm (soft tissue stretch) (due to tension of the joint capsule and ligaments)

beyond 5 degrees of hyperextension is considered

genu recurvatum

The main functions of the patella

increasing the mechanical advantage of the quadriceps muscle and protecting the knee joint (As discussed in Chapter 8 (in the "Torque" section), moment arm is the perpendicular distance between the muscle's line of action and the center of the joint (axis). By placing the patella between the quadriceps, or patellar tendon, and the femur, the action line of the quadriceps muscles is farther away (Fig. 19-6). Hence, the moment arm lengthens, allowing the muscle to have greater angular force. Without the patella, the moment arm would be shorter and much of the muscle's force would be a stabilizing force directed back into the joint)

Osgood-Schlatter disease

overuse injury among growing adolescents

Patellar Tendonitis

overuse stress or sudden impact

The motions possible at the knee are flexion and extension (Fig. 19-2). From 0 degrees of extension, there are approximately ______ to ______ degrees of flexion.

120-135

All three types of arthrokinematic motion occur during knee flexion and extension

Arthrokinematic movements of the knee joint surfaces in a closed-chain activity of knee extension in which the femur moves on the tibia (medial view). (A) Pure rolling of the femur would cause it to roll off the tibia as the knee extends. (B) Normal motion of the knee demonstrates a combination of rolling, gliding (posteriorly), and spinning (medially) in the last 20 degrees of extension.

popliteal cyst

Baker's cyst, is actually misnamed as a "cyst." synovial hernia or bursitis involving the posterior aspect of the knee.

patellofemoral joint

The articulation between the femur and patella is referred to as the

pes anserine

made up of the sartorius, gracilis, and semitendinosusmuscles

the knee has a convex-on-concave relationship in the closed chain, but this is ____________ when non-weight-bearing

reversed - In the open chain, the knee has a concave-on-convex relationship where the concave tibial condyles glide posteriorly with flexion, and anteriorly with extension, while the distal end of the tibia moves in the same direction. The knee is in the open-packed position when it is flexed to 25 degrees, that is the position where most joint play is available. A mobilizing force applied to the proximal tibia in an anterior direction will facilitate knee extension, whereas a posterior glide will promote flexion.

end feel of knee flexion

soft (due to the contact between the muscle bellies of the thigh and leg)

Chondromalacia patella

softening and degeneration of the cartilage on the posterior aspect of the patella, causing anterior knee pain

intracapsular ligaments

stabilizing ligaments located inside joint capsule

The knee joint is the largest joint in the body, and it is classified as a _________________ joint

synovial hinge (not a true hinge, because it has a rotational component)

points to remember

• The body commonly experiences forces such as traction, approximation, shear, bending, and rotation. These forces also have other names. • The muscle's point of attachment to the bone is used to determine leverage. With a second-class lever, resistance occurs between the axis and the force. With a third-class lever, force is in the middle. • The longer the force arm, the easier it is to move the part. Conversely, the longer the resistance arm, the harder it is to move the part. • End feel is the quality of the feel when slight pressure is applied at the end of the joint's passive range. • An open kinetic chain requires that the distal segment is free to move and the proximal segment(s) remains stationary. • To stretch a one-joint muscle, it is necessary to put any two-joint muscles on slack over the joint not crossed by the one-joint muscle. • To contract a two-joint muscle most effectively, start with it being stretched over both joints. • A muscle becomes actively insufficient when it contracts over all its joints as the same time. • When determining whether a concentric or eccentric contraction is occurring, decide • if the activity is accelerating against gravity or slowing down gravity, or • if a weight greater than the pull of gravity is affecting the activity. • Reversal of muscle action occurs when the origin moves toward the insertion.