LP10-11 (The knee) Flashcards
What is the knee, along with the hip & ankle designed for
Designed for mobility and stability. Along with hip and ankle;
- Supports the body when standing
- Functional unit with walking, climbing, sitting
What are the articulations of the knee
- 2 condyles at distal femur
- 2 tibial plateaus on prox tibia.
Large sesamoid bone in quadriceps tendon
Patella
Separates jt. capsule than tibiofemoral jt.
-functions with ankle
Prox. tibiofibular joint
Characteristics of the tibiofemoral joint
Modified hinge joint (BIAXIAL) -Distal femur -Medial condyle locking mechanism of the knee (screw home mechanism) -Two tibial plateaus which are Concave -Medial plateau is larger
ligaments of the tibiofemoral joint
- Anterior cruciate lig
- Posterior cruciate lig
- medial & lateral collateral ligaments
- coronary ligaments
- transverse ligaments
Intracapsular attaching to tibia and femur.
- Named for their attachment on the tibia
- Provide Anterior and posterior support
ACL & PCL
Provide Medial and lateral support
- Medial- attach from the femoral condyle to tibial condyle
- Lateral- attach from the femoral condyle to fibular head.
Medial & lateral collateral ligaments
Connects tibial condyles, meniscus and capsule
Coronary ligaments
Connect anterior menisci to eachother
Transverse ligaments
Joint is covered by medial & lateral fibrocartilaginous menisci
- Two menisci supported by ligaments and muscles
- improve congruency of articulating surfaces
Menisci of the tibiofemoral joint
firmly attached to joint capsule, medial collateral ligament, anterior and posterior cruciate ligaments, semimembranosus
-More secure attachment on the medial meniscus– greater chance of sustaining a tear when there is a lateral blow to the knee
Medial meniscus
attaches to posterior cruciate and the tendon of the popliteus mm through capsular connections.
Lateral meniscus
Arthrokinematics of the tibiofemoral joint
Joint mechanics affected by open and closed chained positions
-rotation occurs with flexion and extension
Tibial motion (open chain) -what is the roll & slide with flexion
Roll: posterior & medial rotation
Slide: Posterior
Tibial motion (open chain) -What is the roll & slide with extension
Roll: Anterior & lateral rotation
Slide: Anterior
Femoral motion (closed chain) -what is the roll & side with flexion
roll: posterior & lateral rotation
slide: anterior
femoral motion (closed chain) -what is the roll & slide with extension
roll: anterior & medial rotation
slide: posterior
concave plateau slides in same direction as physiological movement
Open chain
tibia fixed; convex condyles slide in the opposite direction as physiological movement
Closed chain
Rotation that occurs between femoral condyles and tibia during final degrees of extension.
- Closed chain- tibia fixed with foot on the ground.
- Femur rotates internally – medial condyle slides further posteriorly
- Hip moves into extension
- As knee is unlocked, the femur rotates laterally. This action occurs from the popliteus muscle.
- Pathology or injury to any of the structures affects these movements resulting in the inability to stand upright – lacking this passive stabilizing function.
Screw home mechanism or locking
Characteristics of the patellofemoral joint
Sesamoid bone in quadriceps tendon
- Articulates with intercondylar groove of the anterior distal femur
- Articulating surface covered with smooth hyaline cartilage
- Embedding in anterior portion of joint capsule
- Patellar ligament connects patella to tibia oMany bursa surround patella
Mechanics of the patellofemoral JT
oKnee Extension – patella slides superiorly
oKnee Flexion – patella slides inferiorly
Patellar function
Increase the moment arm of the quadriceps in its function to extend the knee
-The cartilaginous surface of the patella also reduces friction and dissipates forces between the patella and the femoral condyles.
patellar alignment
- Q angle
- Greater in women (approx 10-15degrees)
Formed by two intersecting lines
-ASIS to mid patella & mid patella to tibial tuberosity
Q angle
Patellar Malalignment & Tracking problems:
Increased Q-angle
- Muscle and fascial hypertonicity
- Hip muscle weakness
Posterior patella is not completely congruent as it articulates with femur
- Full extension – patella is superior to patellar groove -15 degrees of flexion – inferior patella begins to articulate with femur -Increased patellar contact as the knee is flexed
- At 90 degrees – patella inferior to patellar groove, quadriceps tendon is in contact.
Patellar contact
Compression force
Full extension – no compression of articular surfaces, little compressive loading from quadriceps due to parallel placement of femur and tibia
- Joint reaction forces rise between 30 and 60 degrees -Peak compression – 75 degrees during open chain movements
- Increase in Q-angle causes an increase lateral pressure as knee flexes
Tibia and fibula bound together by interosseous membrane
- Strong anterior and posterior inferior tibiofibular ligaments at distal tibiofibular articulation
- Strong joint capsule at proximal tibiofibular articulation
- Slight movement between the two bones allows for greater movement of the ankle joint
leg
3 segments of the foot
- hindfoot
- midfoot
- forefoot
talus & calcaneus
hindfoot
navicular, cuboid, & 3 cunieforms
midfoot
5 metatarsals, 14 phalanges
forefoot
Sagittal plane motion around a frontal (coronal axis)
Dorsiflexion (extension)
-Plantarflexion (flexion) oFlexion & extension of the toes
frontal plane motion around a sagittal axis (anteroposterior)
- inversion
- everison
transverse plane motion around a vertical axis
- abduction
- adduction
Pronation/ supination Dorsiflexion/ plantarflexion Eversion/ inversion Abduction/ adduction Lower arch during weight bearing Supination of the forefoot Extension of the 1st metatarsal Flexions of the 5th metatarsal
triplanar motions
superior and inferior tibiofibular joints are separate from the ankle
- Provide accessory motions that allow for greater movement of the ankle
- Ankle mortise
Tibiofibular joint
distal ends of the tibia and fibula form the proximal surface of the ankle or talocrural joint
Ankle mortise
characteristics of superior tibiofibular joint
plane synovial joint
- Articulations are the fibular head and the facet on the posterior aspect of the lateral tibial condyle
- Facet faces posteriorly, inferiorly and laterally
- Has its own joint capsule
- Supported by anterior and posterior tibiofibular ligaments
inferior tibiofibular joint characteristics
Syndesmosis fibrosis joint
- Fibroadipose tissue between articulating surfaces
- Supported by crural tibiofibular interosseous ligament, anterior and posterior tibiofibular ligaments
Tibiofibular Joints Accessory Motions
Fibular accessory movements with plantarflexion and dorsiflexion
-Necessary movement to allow full range of the talus in the mortise during ankle dorsiflexion
Characteristics of the ankle (talocrural) joint
Synovial hinge joint
- Formed by mortise (Tibia & Fibula) and trochlea of the talus
- Thin weak capsule
- Along with Subtalar joint – supported by medial collateral ligaments (deltoid) and lateral collateral ligaments (anterior and posterior talofibular and calcaneofibular ligaments)
- Lateral malleolus extends further distally and posteriorly
- Surface of the mortise is congruent with articulating surface of the body of the talus
wedge-shaped, wider anteriorly, cone shaped apex pointing medially
talus
when foot dorsiflexes what happens to the talus
abducts and everts
when the foot plantarflexes what happens to the talus
adducts and inverts
closed packed position of the talus
dorsiflexion
open packed position of the talus
plantarflexion
Arthrokinematics of the talus
Concave mortise
- Convex talus
- Slide opposite direction of physiological movement
Characteristics of the subtalar (talocalcaneal) joint
The calcaneus and the talus are not lined up equally and work together
- Talus is oriented more medially and the calcaneus more laterally
- 3 articulations between talus and calcaneal
- Biomechanically angular in its orientation
- Multiple planes in which movement occurs
- Pronation and supination in a transverse and sagittal plane
- Eversion and inversion in the frontal plane (isolated only with passive motion)
what are the 3 articulations between talus and calcaneal
posterior, anterior, and middle
what is the subtalar (talocalcaneal) joint supported by
Medial and lateral collateral ligaments (same supporting structures as talocrural joint)
- Interosseous talocalcaneal ligament in tarsal canal
- Posterior and lateral talocalcaneal ligaments
posterior articulation of the subtalar (talocalcaneal) joint
concave talus, calcaneus convex (independent joint capsule)
anterior and middle articulations of the subtalar (talocalcaneal) joint
convex talus, calcaneus concave
open chained position of the subtalar (talocalcaneal) joint
convex posterior portion of calcaneus slides opposite to motion
-concave middle and anterior portions side same direction (like a door knob/tap)
Talonavicular joint
supported by a series of ligaments
- Articulation with the talus (allows for functions with subtalar joint) – triplanar motions of the subtalar joint
- During weight bearing the talus moves plantarward and medially, decreasing the medial longitudinal arch= pronation oResults in a upward and outward motion of navicular
- Opposite occurs with supination
Arthokinematics of the Talonavicular joint
Head of talus – convex
-Articulation with navicular – concave oNavicular sides in the same direction of motion of forefoot
open chained position for the Talonavicular joint (w/ supination & pronation)
pronation – navicular slides dorsally and laterally
Supination – navicular slides plantarly and medially
characterics of the transverse tarsal joint
joint between hindfoot and midfoot
- Triplanar motions of the foot and makes compensatory movements to adjust to variations in the ground
- The calcaneocuboid is a saddle joint
Convex dorsal to plantar
concave medial to lateral
calcaneus
opposite of calcaneus
cuboid
intertarsal & tarsometatarsal joints
Plane joints
Reinforce the function of transverse tarsal joint
During weight bearing – help regulate the position of the forefoot on the ground
metatarsophalangeal & interphalangeal joints
same as MCP and IP joints of the hand
Extension more important than flexion, opposite to the hand
Necessary for normal walking (especially extension of the MTP joints)
Large toe does not function separately, unlike the hand
convex, two asymmetrical condyles
Distal femur
longer, contributes to locking mechanism of the knee (screw home mechanism) -Two tibial plateaus which are Concave
medial condyle
