Midterm Review Flashcards
Synovial Membrane and Fluid
Membrane is made of 2 layers: Intima and Subintima
Subintima is vascularized and innervated
Functions of synovial membrane
2 Functions
Produces and resorbs synovial fluid
Provides immunity to joint cavity (sub)
Fibrous capsule Function
Support/stabilize
Guide and limit motion
Absorb shock
Fibrous capsule components
Capsular ligaments
Extracapsular ligs
Attachment sites
Vascularized and innervated
Extremity Joint components
Subchondral bone (10x stiffer than bone) Articular cartilage Intra-articular cartilage Fibrous capsule Synovial membrane Synovial cavity Synovial cavity Periosteum
Synovial Fluid
Rich in GAG's especially Hyaluronic Acid Shock absorption Lubrication Nutrient supply to cartilage Waste product removal from cartilage
Bursae - General
Synovial membrane lined extra-capsular pockets or pouches
Some communicate with the synovial cavity
Bursae Function
Lubrication
Padding the joints
Articular Cartilage
Hyaline is most common
Joints lined by fibrocartilage: AC, SC, TMJ, 1/2 of SI
Main Components of Articular Cartilage
Low cell population density
H2O (80% of total weight)
Collagen (60-70% of dry weight)
GAG (proteoglycans , 30-40% of dry weight)
Function of collagen
Provide cartilaginous framework
Provide tensile strength
Sources of Nutrition for Articular Cartilage
Synovial fluid
Subchondral bone
Two types of Intra-Articular Cartilage
Disc - AC, SC, TMJ, T.F.C
Meniscus - AC, knee
Intra-Articular Cartilage (Innervation, vascularized, function)
Innervated:
Outer transition with capsule
Proprioception
Nociception
Vascularized:
Outer - 1/3
Functions: Increased shock absorption Increased congruency increased stability Decreased function Increased motion
Cartilage loads
Small compressive loads only:
Weak ionic bonding
Fails @ high compressive loads
Large compressive loads —> squeezes fluid film out of the cartilage
Slow oscillations are good: Stimulates matrix synthesis and inhibits chondrolysis
Rapid oscillations or no oscillations are bad: Supresses matrix synthesis and enhances chondrolysis
Changes in DJD (Articular Cartilage)
Cell numbers, GAGs, lubrication decreases. Serous fluid, calcification increases
Changes in DJD (Subchondral Bone)
Increase calcification: Increase rigidity
Increase thickness: impedes waste removal and nutrient delivery
Decrease shock absorption
Changes in DJD (Intra-articular cartilage decreases)
Vascularization, chondrocyte population, GAGS and collagen, shock absorption and flexibility
Spheroid
Ball and socket
Arthroid
Planar/gliding
Sellar
Saddle
Ellipsoid
Condyloid
Gingylmus
Hinge
Trochoid
Pivot
Osteokinematics
Uniaxial, biaxial, polyaxial, nonaxial
2 types of motion:
Spin - Stationary mechanical axis
Swing - Mechanical axis moves
Conjoint/conjunct rotation:
Involuntary movement that occurs during swing
Screw home mechanism
Convex Rule
Convex on Concave surface movement the convex surface will roll and slide in the opposite direction
Rolls in the same direction as angular motions
Slides in the opposite direction of angular motion
GH JOINT
Concave Rule
for a concave on convex movement. Concave slides and rolls in the same direction as the movement
Roll is in the same direction as angular motion
Slide is in the same direction as angular motion
Tibia on Femoral Extension
Closed
Open
Resting position
Neutral position
Tight packed position
Loose packed position
Joint capsule is most relaxed
Joint position at zero degrees
Gait cycle terms (R/L Step Length, R/L Foot Angle, Step width, Stride Length)
Step length is the length of one foot fall to the other during walking
Foot angle is the angular deviation of the forefoot from the hind foot
Step width is the lateral difference between foot landings
Stride length is the length from one step to the same foot during walking
Step Width avg
8-10 cm
Foot Flare/Angle avg
5-7 degrees when walking
Increase stress on lower extremity leads to injury
inefficient motion leads to increased muscle work and decreased stride length
Phases of gait cycle
Swing - toe off to foot strike, recovery
Stance - Foot strike to toe off, support
Walking stances
60% stance, 40% swing
Double support
Running stances
60% Swing, 40% Stance
Float
Foot Strike
lands ahead of COG
Absorbs shock and adapts to the ground
Foot lands 2 degrees supinated and then pronates
Eversion of calcaneus
abduction of foot and the calcaneus
Dorsiflexion of calcaneus
Tibia and femur Internally Rotate
Rearfoot striker
Walking, jogging, slow running
foot and talus plantar flexes
Tibialis anterior eccentrically controls the plantar flexion and pronation of the foot
Forefoot striker
Fast running
Foot dorsiflexes
Gastroc-Soleus controls dorsiflexion
Tibialis anterior and posterior control pronation
Midstance
COG is directly over the stance limb
Foot is pronates relative to neutral
Inversion, adduction and plantar flexion of the calcaneus
Tibia and femur extend and externally rotate
Take off
COG is anterior to the stance foot
Tibialis anterior rapidly inverts the calcaneus. This will help to lengthen the leg so that the opposite foot does not hit the ground
Weight of plantar surface shifts medially across metatarsal break
Peroneus longus lifts cuboid and lateral foot and depresses and plantar flexes first ray
Slight pronation occurs at the end of take off
Swing phases
Initial swing
Mid swing
Terminal swing
Stance phases
Footsrike
Midstance
Take off
Initial swing
knee flexes and tibia internally rotates
Hip extends and externally rotates
Hip flexors eccentrically decelerate
Mid-swing
Hip flexors contract to accelerate leg
Gluteals and hamstrings eccentrically contract to decelerate the limb
Foot goes from neutral to slightly dorsiflexed to avoid contact with the ground
Terminal Swing
Hip extensors and knee flexors accelerate the limb backwards
Hamstrings
6 important joints of the foot and ankle
Talocrural Subtalar (pronation and supination Choparts or midtarsal Lisfranc’s Tarsometatarsal jont Metatarsalphalangeal
Rear foot bones
Calcaneus and talus
Midfoot bones
Navicular, cuboid, cuneiforms
Forefoot
metatarsals, phalanges (also called rays)
Arches of the foot KEYSTONES
Medial: talus
Lateral: cuboid
Transverse: 2nd metatarsal
Arches of the foot STAPLES
Medial: spring ligament
Lateral: plantar ligament
Transverse: transverse metatarsal ligament
Arches of the foot TIEBEAMS
Plantar fascia
Intrinsic muscles
Arches of the foot SUSPENSORS
Medial: anterior and posterior tibialis
Lateral and transverse: Peroneus longus and brevis
Plantar Fascia
Inelastic tiebeam
Medial and lateral calcaneal tubercle to the bones and fascia of the toes
Tenses when someone rises on toes or walks
Windlass effect
Intrinsic muscles of the foot
act as springlike tie beams to support the arch
can fatigue with pronation syndrome and overuse
Subtalar joint
Locks and unlocks the transverse tarsal joint
in a pronated state the transverse tarsal joints are parallel and unlocked - increased flexibility
In a supinated position the joints are twisted and locked - increased stiffness
Pes cavus - Supinated foot
High arch Inverted heel Curved, stiff Decreased shock absorption Lateral shoe wear down Weakened tibialis anterior allows peroneus longus to pull foot into plantar flexion
Metatarsalgia and stress related injuries
Metatarsals are at a greater angle to the ground
Static Listings of Pes Cavus
Inverted, anterior calcaneus Lateral talus Superior navicular Plantar flexed metatarsal Extended proximal phalanges
Supinated weight bearing foot lengthens the lower limb
Pes Planus - Pronated foot
Low arch, arch appears normal when unweighted but drops when under load
Everted heel (rearfoot valgus)
Straight and usually flexible
Decreased shock absorption
Medial shoe breakdown
Overstretched or weakened spring ligament, plantar fascia, and tibialis posterior tendon
Pes planus - Static listings
Everted, posterior calcaneus Medial talus Inferior navicular Dorsiflexed metatarsals Flexed proximal phalanges Pronated weight bearing foot shortens the lower extremity
Rearfoot Varum
Inverted position of the hind foot
common cause of pronation syndrome
Forefoot varum
Medial forefoot is elevated
Excessive pronation that lasts into takeoff
Inhibited supination during takeoff
Forefoot Valium
Lateral forefoot is elevated
Often leads to decreased pronation and ankle sprains
Posting and shoes
Forefoot varus - medial forefoot post
Rearfoot varus - medial rearfoot post
Forefoot valgus - lateral forefoot post
