Knee

"W" sitting position may lead to what? what is stressed in this position?

"W" sitting position may lead to excessive *lateral tibial torsion* MCL is stressed

what connects the lateral meniscus to the femur?

*Anterior and posterior meniscofemoral ligaments* connecting the lateral meniscus to the femur may also be present.

patellofemoral instability

*Instability includes subluxation or dislocation related to a single episode or recurrent episodes.* Instability may be related to an abnormal - Q-angle - dysplastic trochlea (shallow groove or flat lateral femoral condyle) -patella alta -tight lateral retinaculum -or inadequate medial stabilizers (vastus medialis oblique muscle and medial patellofemoral ligament). Patellar instability is most often in a *lateral direction. * Dislocation may derive from direct trauma to the patella or from a *forceful quadriceps contraction* while the foot is planted and the femur is externally rotating while the knee is flexed. Recurrent dislocation is usually an indication for surgery to reorient the stabilizing forces across the PF joint.

Tears of the Collateral Ligaments: LCL and MCL what type of force? which ligament is most commonly injured?

*The lateral collateral ligament is injured from a varus force.* The medial collateral ligament is typically injured as a result of a valgus force. The medial ligament is the more commonly injured collateral and is often associated with tears of the joint capsule and medial meniscus, to which it is firmly attached. Severe injuries will damage the anterior cruciate ligament as well; *this combination of injuries is referred to as O'Donoghue's terrible (orunhappy)triad*

what meniscus is more prone to injury if discoid meniscusis is present?

*The lateral meniscus is more prone to injury, however, if a developmental abnormality often referred to as a discoid meniscusis* present. A discoid lateral meniscus is an enlarged, thickened meniscus, theorized to be caused by repetitive movements. *An abnormally wide lateral radiographic joint space may be evident on the AP knee projection if this condition exists.* • Discoid meniscus instead of being C shape it's a zero shape

Patellofemoral Subluxations

Acute traumatic dislocations of the patellofemoral joint are not uncommon . The usual mechanism is a *direct blow to a flexed knee, as in a motor vehicle accident*, or a *powerful quadriceps contraction superimposed on a rotary or valgus force at the knee*, as when a *runner is cutting* to the direction opposite his or her planted foot. Chronic subluxations of the patella are much more common than true dislocations.

if misalignments are excessive what can it lead to? These excessive differences are referred to as what? and include what?

Alignment is often different between males and females. Some of these misalignments, if excessive, can lead to *patellofemoral symptoms or instability.* These excessive differences are sometimes referred to as miserable malalignment syndrome and can include *anterior pelvic tilt, increased hip anteversion, decreased tibiofemoral angle, genu recurvatum, navicular drop, and increased foot pronation.*

AP stability of the knee is provided by what?

Anteroposterior stability is provided by the *cruciate ligaments; mediolateral stability is provided by the medial (tibial) and lateral (fibular) collateral ligaments (MCL and LCL),*

Osteochondritis Dissecans (OCD) Mechanism

As in the case of osteochondral fracture, shearing and rotational forces act to detach a fragment of articular cartilage and subchondral bone. o Hope to patch the piece up if it has subchondral bone

Axial rotation occurs between what bones? due to what? in non weight bearing during extension and flexion what direction does the tibia rotate?

Axial rotation occurs between the tibia and femur as the knee flexes and extends due to the asymmetrical condyles. *In nonweight bearing extension the tibia rotates laterally on the femur, and with flexion it rotates medially.*

what meniscus has a greater chance of sustaining tears and why?

Because the medial meniscus has more extensive attachments than the lateral meniscus, it has a greater chance of sustaining a tear when there is trauma to the knee.

Hip muscle weakness.

Hip abductor and external rotator weakness may result in femur adduction and knee valgus and contribute to increased medial rotation of the femur observed under weight bearing in subjects with patellofemoral pain syndrome.

Impairments that may contribute to biomechanical dysfunction of PF include (4)

Impairments that may contribute to biomechanical dysfunction include: - a tight lateral retinaculum -weak vastus medialis obliquus (VMO) muscle -neuromuscular deficits in the hip musculature -and generalized joint hypermobility. These impairments usually result in clinical evidence of abnormal patellar tracking, and there may be *discordant firing of the quadriceps muscle.*

what provides the patella dynamic stabilization?

In addition to the bony restraints of the trochlear groove (femoral sulcus), the patella is stabilized by passive and dynamic restraints. -The superficial portion of the *extensor retinaculum, to which the vastus medialis (VM) and vastus lateralis (VL) muscles attach, provides dynamic stability to the patella in the transverse plane.*

lateral meniscus cyst

More inferior and lateral swelling

Normal female alignment (8)

Normal female alignment with wider pelvis, femoral anteversion, genu valgum, hyperflexibility, lateral tibial torsion, and narrow notch

normal male alignment

Normal male alignment demonstrates a narrower pelvis, more developed musculature, genu varum, medial or neutral tibial torsion, and wider notch.

what type of problems can occur at the PF jt?

Patellofemoral could have instability problems an/or patellar pain due or not due to malignment

Anterior Instability anterolateral instability (2) Anteromedial instability (1)

anterolateral instability: ACL and ITB Anteromedial instability: MCL (deep and superficial )

Ligament Injuries in Female Athletes Risk Factors (4)

biomechanical, neuromuscular, structural, and hormonal

Hormonal

differences between males and females may also be a factor related to the increased incidence of female ACL injuries. There are hormone receptor sites for estrogen, progesterone, and testosterone in the ACL of humans. The sex hormones have a time-dependency effect that influences ACL tissue characteristics, such as increasing risk of injury during the pre-ovulatory phase of the menstrual cycle in females. • Menses

Structural risk factors

include *femoral notch size, ACL size, and lower extremity alignment.* The femoral notch height is smaller and notch angle larger in the male compared to the female, which may affect ACL size. The female ACL is smaller than the male ACL even when adjusted for body size. The ACL in the female has a lower modulus of elasticity (i.e., less stiff) and lower failure strength (i.e., fails at a lower load), leading to greater joint mobility than in the male. • Bony stuff

Biomechanical risk factors

include the effect of the total chain (trunk, hip, knee, and ankle) on ACL injuries, including awkward or improper dynamic body movements during activities such as deceleration and changes of direction. For example, *increased hip adduction is related to increased knee valgus, which is associated with ACL injury risk in the female. Also, decreased hip and knee flexion angles have been demonstrated during cutting activities in the female athlete. *

Passive lateral glide test

move lateral more 50 %-> hypermobile at risk for sublux Passive medial and lateral movement of the patella is also carried out to determine its mobility and to compare it with the unaffected side. Normally, the patella should move up to half its width medially and laterally in extension (Figure 12-32). When the patella is pushed medially or laterally, the examiner should note whether it stays parallel to the femoral condyles or whether it tilts or rotates. For example, if pushed medially when the medial structures are tight, the lateral border of the patella tilts up. Likewise, tight lateral structures cause the medial border to tilt up. If the lateral structures are tight superiorly, the inferior pole of the patella medially rotates

Sinding-Larsen-Johansson disease Osgood-Schlatter disease

•Sinding-Larsen-Johansson disease refers to the disorder at the proximal patellar attachment, and Osgood-Schlatter disease refers to the disorder at the distal patellar attachment. o Schlatter is the distal patellar attachment o Larsen: proximal patella attachment

Genu Varum

•The etiology of genu varum may also be highly varied, related to renal or dietary rickets, epiphyseal injury, osteogenesis imperfecta, or medial tibial osteochondritis, known as Blount's disease.

what is the most common noncontact occurs through what?

•The most common noncontact injury occurs through a rotational mechanism in which the tibia is *externally rotated on the planted foot.* Literature supports that this mechanism accounts for as many as 78% of all ACL injuries. The second most common noncontact mechanism is forceful *hyperextension of the knee.*

Increased Q-angle: what happens during knee flexion during wb? structurally what causes Q angle? (5) what lower extremity motion increases the Q angle (4)?

•With an increased Q-angle, there may be increased force between the *lateral patellar facet and lateral femoral condyle *when the knee flexes during weight bearing. Structurally, an increased Q-angle may occur with a *wide pelvis, femoral anteversion, coxa vara, genu valgum, and/or laterally displaced tibial tuberosity.* Lower extremity motions in the transverse plane that may increase the Q-angle are *external tibial rotation, internal femoral rotation, and a pronated subtalar joint*. Dynamic knee valgus (see Fig. 21.9), where the knee joint center moves medially relative to the foot during weight-bearing activities, also increases the Q-angle.

Screw-Home Mechanism what is it? unlocking th knee occurs indirectly and directly from what?

-*The axial rotation that occurs between the femoral condyles and the tibia during the final degrees of extension is called the locking, or screw-home, mechanism.* - When the tibia is fixed with the foot weight bearing on the ground, terminal extension results in the femur rotating internally (the medial condyle slides farther posteriorly than the lateral condyle). Concurrently, the hip moves into extension. Tension in the iliofemoral ligament, which occurs with hip extension, reinforces the medial rotation of the femur to lock the knee. As the knee is unlocked, the femur rotates laterally. -*Unlocking of the knee occurs indirectly with hip flexion and directly from action of the popliteus muscle. Individuals who cannot lock their knee into extension because they lack full hip extension (hip flexion contracture) are unable to benefit from this passive stabilizing function during standing.*

ACL injuries can occur from what? what is the most common contact mechanism? what does it injure?

-ACL injuries can occur from both *contact and noncontact mechanisms* (Fig. 21.12). -The most common contact mechanism is a force applied to *the lateral side of the knee that results in a large valgus moment.* -This mechanism can injure not only the *ACL, but also the MCL and the medial meniscus.* Such an injury is termed the *"unholy triad" or "terrible triad"* injury because of the frequency with which these three structures are injured in a single trauma (Fig. 21.13).

KT-1000 arthrometer

-How much laxity there is, it gives you a number -Quantifying device -anterior and posterior drawer

what are the specific alignment alterations for the PF jt? (2)

-Patella alta or baja -lateral patellar tilt are specific alignment alterations possible at the patellofemoral joint.

what provides the patella passive stabilization?

-The *medial and lateral patellofemoral* ligaments, which attach to the *adductor tubercle* medially and *iliotibial (IT) band laterally*, provide passive restraints to the patella in the transverse plane.

what stabilizes the patella against the superiorly directed pull of the quadriceps?

-The *medial and lateral patellotibial* ligaments and *patellar tendon* combine to stabilize the patella against the superiorly directed pull of the quadriceps muscle group.

The menisci improves what? how are they connected to the tibial condyles and capsule? to each other? patella ?

-The menisci improve the *congruency of the articulating surfaces. * -They are connected to the tibial condyles and capsule by the *coronary ligaments, to each other by the transverse ligament, and to the patella via the patellomeniscal ligaments. *

patellar malaligment and tracking problems are caused by what?

-increased Q angle - muscle and fascial tightness -Hip muscle weakness

Baker's Cyst

: *posterior capsule is more lax than it should be.* Lock knee's see it extension of the synovium coming out through the back. Could put pressure on nerve endings=pain. such as a popliteal (Baker's) cyst, which is caused by herniation of synovial tissue through a weakening in the posterior capsule wall

what are the two articulations in the knee jt?

A lax joint capsule encloses two articulations: the tibiofemoral and the patellofemoral joints

Meniscus Tears: Common Impairments and Activity Limitations

A meniscus tear can cause *acute locking of the knee or chronic symptoms with intermittent catching/locking. * There is joint swelling and some degree of quadriceps atrophy, with pain along the joint line during forced hyperextension or maximum flexion due to stress to the coronary ligament. When there is joint catching/locking, the knee does not fully extend and there is a springy end feel with passive extension. When the joint is swollen, there is usually end-range flexion or extension motion limitation. The McMurray test or Apley's compression/distraction test may be positive. -With an *acute meniscus* tear the patient may be unable to bear weight on the involved side. *Unexpected locking or giving way during ambulation often occurs, causing safety problems.*

Muscle and fascial tightness: what prevent the medial translation of the patella? tight what results in pronation of the foot? what happens when the ankle dorsiflexes? what two muscles may affect the knee and lead to compensations?

A tight *IT band and lateral retinaculum* prevent medial translation of the patella. *Tight ankle plantarflexors* result in *pronation* of the foot when the ankle dorsiflexes, causing *lateral torsion of the tibia* and functional lateral displacement of the tibial tuberosity promoting an increased lateral force on the patella.*Tight rectus femoris and hamstring* muscles may affect knee mechanics and lead to compensations.

Patellofemoral jt characteristics what type of bone is the patella? it articulates with what? on the anterior aspect of the distal femur? how is it connected to the tibia?

Characteristics. The patella is a *sesamoid bone in the quadriceps tendon.* It articulates with the *intercondylar (trochlear) groove* on the anterior aspect of the distal femur. Its articulating surface is covered with smooth hyaline cartilage. The patella is embedded in the anterior portion of the joint capsule and is connected to the tibia by the *ligamentum patellae.* Many bursae surround the patella.

When you flex and extend the leg what direction does the tibia rotate?

Flexion with medial rotation Extension with lateral rotation

Fractures of the Distal Femur Mechanism

Fractures of the distal femur occur when great force is applied, as in *motor vehicle accidents or falls from great heights*. Low-level forces or *minor falls can cause fracture if the bone is weakened by preexisting osteoporosis* or other pathology.

Fractures of the Proximal Tibia Mechanism : (3)

Fractures of the proximal tibia in adults occur most frequently at the *medial and lateral tibial plateaus, when varus or valgus forces* combined *with axial compression* cause the hard femoral condyle to impact and depress the softer tibial plateau. A common mechanism of injury is a *car-pedestrian accident* in which the *car's bumper strikes the pedestrian's knee* (Fig. 13-46). Elderly patients with *osteoporosis* are more likely to sustain a tibial plateau fracture than a soft tissue injury after a *twisting injury* to the knee.

Meniscal Tears : Mechanism of injury

Mechanism of Injury Meniscal tears occur during *shear, rotary, and compression forces that abnormally stress* the fibrocartilaginous tissues. The *medial meniscus is more frequently injured than the lateral meniscus* because of its greater peripheral attachment and decreased mobility, impairing its ability to withstand imposed forces.

Tears of the Cruciate Ligaments Mechanism of Injury PCL ACL knee dislocations rupture what? (4) what can be limb threatening?

Mechanisms of injury to the *posterior cruciate ligament involve external forces that strike the anterior aspect of the knee, as in dashboard injuries *(Fig. 13-60). Mechanisms of injury to the* anterior cruciate ligament involve noncontact forces that place great valgus and rotary stresses on the knee*, as when an athlete suddenly decelerates, turns, and hears the classic "pop" of a rupture Knee dislocation, a rare occurrence caused by high-energy trauma, ruptures at least three of the four major ligamentous structures of the knee. Knee dislocation, a rare occurrence caused by high-energy trauma, ruptures at least three of the four major ligamentous structures of the knee. *Knee dislocations rupture the cruciates and cause, at varying degrees, injury to the collaterals, capsule, and menisci (Fig. 13-62). Associated neurovascular injury can be limb threatening. * • Knee dislocation: cruciate and collateral

Meniscal Tears Clinical Presentation

Meniscal tears are *common sports-related and age-related injuries.* Isolated tears present with intermittent clicking and eventually chronic *blocking or locking of knee joint *motion, accompanied by episodes of *effusion and pain*.

Miserable malalignment syndrome (5)

Miserable malalignment syndrome is a term coined to describe patients who have *increased femoral anteversion, genu valgum, vastus medialis obliquus (VMO) dysplasia, lateral tibial torsion, and forefoot pronation.* These factors create excessive lateral forces and contribute to patellofemoral dysfunction.

Posterior Posteromedial (6) Posterolateral (3)

Posteromedial: sartoirus, gracilis, semimembranosus, semitendinosus, medial gastro, PCL, Posterolateral: lateral gastro, popliteal tendon , LCL

Tibiofemoral Joint Resting Position CPP CP

Resting position: 25° flexion Close packed position: Full extension, lateral rotation of tibia Capsular pattern: Flexion, extension

PF Pain Without Malalignment: Soft Tissue lesions (5) (7)

Soft tissue lesions: Soft tissue lesions include: • plica syndrome • fat pad syndrome • tendonitis • IT band friction syndrome • prepatellar bursitis. • Tight medial and lateral retinacula or patellar pressure syndrome. • Osteochondritis dissecans of the patella or femoral trochlea. • Traumatic patellar chondromalacia. • PF OA. • Apophysitis. • Symptomatic bipartite patella. • Trauma.

what position maintains normal medial torsion?

Tailor position maintains normal medial tibial torsion.

The _____ bony partner is composed of two asymmetrical condyles on the distal end of the femur. The _____ condyle has a longer surface than the _____ condyle, which contributes to what?

The *convex* bony partner is composed of two asymmetrical condyles on the distal end of the femur. The *medial* condyle has a longer surface than the *lateral condyle,*which contributes to the locking mechanism at the knee.

Meniscus: Mechanisms of Injury what injures more frequently?

The *medial meniscus is injured more* frequently than the lateral meniscus. Meniscal injuries may occur during femur on tibia rotation during weight bearing when the foot is firmly fixed on the ground, as when pivoting, *getting out of a car, or in many sport- or work-related activities.* *Medial meniscus injuries often accompany ACL tears*. Simple *squatting or high-force* trauma may also cause a meniscus tear.

Q- Angle: norm

The Q-angle is the angle formed by two intersecting lines: one from the anterior superior iliac spine to the midpatella and the other from the tibial tubercle through the midpatella. A normal Q-angle, which tends to be *greater in women* than men, *is 10° to 15°.* A higher Q-angle suggests greater *lateral bowstring forces on the patella*.

The ______ bony partner is composed of two tibial plateaus on the proximal tibia with their respective fibrocartilaginous menisci. The ______ plateau is larger than the ______ plateau.

The concave bony partner is composed of two tibial plateaus on the proximal tibia with their respective fibrocartilaginous menisci. The medial plateau is larger than the lateral plateau.

The lateral meniscus attaches to what?

The lateral meniscus attaches to the *PCL and the tendon of the popliteus muscle through capsular connections.*

The medial meniscus is firmly attached to the joint capsule as well as ? (4)

The medial meniscus is firmly attached to the joint capsule as well as to the *MCL, anterior and posterior cruciate ligaments (ACL and PCL), and semimembranosus muscle.*

Articulation between patella and femur The odd facet does not come into contact with the femoral condyles until what?

The odd facet does not come into contact with the femoral condyles until at least 135° of flexion is reached.

Patellar Loading with Activity

Walking: 0.3 times the body weight Climbing stairs: 2.5 times the body weight Descending stairs: 3.5 times the body weight Squatting: 7 times the body weight

Closed Chain: slide in what direction?

With motions of the femur on a fixed tibia while in a weight-bearing, closed kinematic chain, the convex condyles slide in the direction opposite to the bone motion

Open chain: plateuas slide in what direction?

With motions of the tibia while in a nonweight-bearing, open kinematic chain, the *concave plateaus slide in the same direction* as the bone motion

what motion is important to get first? and what is the resting position for a swollen knee?

extension and slightly flexed position If there is intracapsular swelling, or at least sufficient swelling, the knee assumes a position of 15° to 25° of flexion, which provides the synovial cavity with the maximum capacity to hold fluid. This position is also called the resting position of the knee. Is the swelling intracapsular or extracapsular? Intracapsular swelling is evident over the entire joint; extracapsular swelling tends to be more localized

what is an example of extracapsular swelling?

extracapsular swelling tends to be more localized

, The circles depicted on the patella indicate the point of maximal contact between the patella and the femur. As the knee is extended, the contact point on the patella migrates where?

from superior to inferior pole. Note the suprapatellar fat pad deep to the quadriceps

Neuromuscular risk factors

have an influence on biomechanical factors in that neuromuscular control influences joint position and movement. *Valgus collapse at the knee and decreased use of the hip extensors* have been reported to be more common in women who have sustained an ACL injury than in men with an ACL injury. It is suggested that this is related to increased anterior shear of the tibia and strain of the ACL during deceleration such as landing with hip-knee flexion following a jump. Not only are females weaker in hip and knee strength compared to males (normalized to body weight), but *muscle timing and activation patterns of the quadriceps, hamstrings, and gastrocnemius muscles also differ between males and females.* • Timing issues • Awareness issues such as dynamic valgus

DJD what is it? primary causes? Secondary causes? (3)

• Degenerative joint disease (DJD), or *osteoarthritis*, of the knees is present radiographically to some degree in the majority of people over age. Repetitive *mechanical and compressive stresses from occupational, recreational, athletic, and normal activities* of daily living over many decades typically result in degenerative changes in the joints. Also, *secondary degenerative changes are long-term sequelae of previous fracture, meniscal, or ligamentous injury*.

Active Movements of the Knee Complex

• Flexion (0° to 135°) • Extension (0° to 15°) • Medial rotation of the tibia on the femur (20° to 30°) • Lateral rotation of the tibia on the femur (30° to 40°) • Repetitive movements (if necessary) • Sustained postures (if necessary) • Combined movements (if necessary)

Passive Movements of the Knee Complex and Normal End Feel

• Flexion (tissue approximation) • Extension (tissue stretch) • Medial rotation of tibia on femur (tissue stretch) • Lateral rotation of tibia on femur (tissue stretch) • Patellar movement (tissue stretch—all directions)

Resisted Isometric Movements of the Knee Complex

• Flexion of the knee • Extension of the knee • Ankle plantar flexion • Ankle dorsiflexion • Hip abductors (in alignment cases) • Hip lateral rotators (in alignment cases)

Osteochondral fractures Mechanism

• It is most often *sports-related injuries involving combinations of shear, rotation, and impaction* forces at the knee that damage the *articular cartilage* (chondral fracture) or the articular cartilage and underlying subchondral bone (osteochondral fracture).

Instabilities About the Knee

• One-plane medial instability • One-plane lateral instability • One-plane anterior instability • One-plane posterior instability • Anteromedial rotary instability • Anterolateral rotary instability • Posteromedial rotary instability • Posterolateral rotary instability

Genu Valgum

• The etiology may be familial, related to hip or foot positioning, associated with trauma to the physeal plate, fractures, or neurological deficits, or it may be idiopathic. The AP radiograph of the entire lower extremity adequately demonstrates this deformity.

Fractures of the Patella two injuries? avulsion?

• The patella is vulnerable to two types of injury. *Falls or dashboard impactions* fracture the patella as it is compressed against the femur. *Avulsion fractures occur when the patella is pulled apart by forceful contraction of the quadriceps coupled with passive resistance of the patellar ligament*. This is seen when a person attempts to keep from falling after tripping. o Soccer player

Osteochondritis Dissecans (OCD)

• This condition is seen in older children, teenagers, and young adults, particularly those active in sports. Dull pain and chronic joint effusions are exacerbated with weight-bearing activity. *OCD has come to be considered a chronic form of osteochondral fracture. The non-weight-bearing medial femoral condyle is involved 85% of the time. *

Sequential Functional Tests for the Knee (10)

• Walking • Ascending and descending stairs (walking → running) • Squatting (both knees should flex symmetrically) • Squatting and then bouncing at the end of the squat (again, the two knees should act symmetrically) • Running straight ahead • Running straight ahead and stopping on command • Vertical jump • Running and twisting (figure-eight running, carioca) • Jumping and going into a full squat • Hard cuts, twists, pivots

Osteochondral fractures

• are commonly seen in young athletes. The *femoral condyles, tibial plateaus, or patella may sustain an osteochondral fracture.* The *lateral femoral condyle* is often involved, and the injury may be related to a *transient patellar dislocation.* The severity of the injury may range from only a minor indentation of the articular cartilage to a portion of the articular cartilage becoming detached, often taking with it a piece of subchondral bone. o Patella dislocates laterally o Hit condyle hard