KinesiologyQuiz3Weeks8-10 Flashcards
Inominate
union of ilium, pubis, and ischium; anterior connection is the pubic symphysis, posterior connection is the sacrum (SI joint)
What populations commonly injure the acetabular joint?
young (dislocation) and elderly (degenerative)
During standing, what is the alignment of the inominate?
ASIS to pubic tubercle (lateral view - sagittal plane view)
Where does the inguinal ligament attach?
pubic tubercle on the pubis
Pubic Symphysis
completes anterior pelvic ring, hyaline cartilage (synarthrosis - relatively immobile), stress relief - walking, childbirth (moves slightly)
What separates the greater sciatic and lesser sciatic notch?
ischial spine
Femur - Angle of Inclination
angle within the frontal plane for optimal alignment of joint surfaces, normal angle is 125 degrees, starts larger, in coxa valga, but decreases due to loading (SAID)
Femur
longest and strongest bone, convex head, natural valgus at knee, bowing effect - anterior convexity, linea aspera - prominent line muscular attachment of v. medialis & v. intermedius
Coxa Vara
angle of inclination markedly less than 125 degrees, stress fractures in neck in elderly, sharp angle causes femur to rotates medially in the frontal plane to compensate sharp angle (more fractures in femoral neck)
Coxa Valga
angle of inclination markedly greater than 125 degrees, arthritis common because acetabulum is not sharing forces, femur rotates laterally in the frontal plane to compensate large angle (more dislocations)
Femur - Torsion Angle
normal anteversion - 15 degrees, anything markedly greater is excessive anteversion and markedly less is retroversion
Femur Torsion Angle Compensatory Mechanisms
abnormal anteversion - in-toeing; retroversion - out-toeing
What type of bone primarily occupies the femoral head and why?
cancellous bone, absorbs stress
The femoral head contacts the acetabulum surface through what structure?
lunate surface - thickest cartilage is along the superior-anterior to the fovea
What is the primary function of the lunate surface?
flattens slightly as the acetabular notch widens slightly, thereby increasing contact area as a means to reduce peak pressure
What is the fovea?
pit that contains ligamentum teres & branch of the obturator artery (some vascularity), most vascularity is through the joint capsule
Why could avascular necrosis of the femoral neck and head occur?
because most of the vascularity in this region is in the joint capsule rather than the bone itself
Describe the change in the area of joint surface contact during swing phase to mid stance phase of walking.
20% of the lunate surface during the swing phase to about 98% during the mid stance phase
Acetabular Alignment
acetabulum projects laterally from the pelvis with a varying amount of inferior and anterior tilt
Center Edge Angle
extent to which acetabulum covers femoral head within frontal plane, 35-40 degrees is normal, lower angle = increased risk of dislocation
Acetabular Anteversion Angle
extent acetabulum surrounds femoral head in horizontal plane, normal is 20 degrees, high angle = anterior hip dislocation
Which ligaments reinforce the hip joint capsule?
iliofemoral, pubofemoral, ischiofemoral
Iliofemoral Ligament
Y ligament, thick and strong, taut in extension & lateral fibers with external rotation, femoral head rests on it during full extension
Pubofemoral Ligament
taut with hip abduction and extension
Ischiofemoral Ligament
superficial fibers - taut in internal rotation and extension, superior fibers - taut in adduction, inferior fibers - taut in flexion
What is closed pack position for the hip?
full extension, slight abduction, slight internal rotation (taut position of ligaments)
What is maximal joint congruency for the hip?
90 degrees of flexion, moderate abduction and external rotation (most contact area)
Which ligament of the hip would a quadraplegic rely on to stand?
iliofemoral ligament
Why would someone with capsular swelling in the hip walk hunched over?
attempting to achieve 60 degrees of hip flexion where intracapsular pressure is least (shortened and tight iliopsoas, erector spinae are stretched and weak)
Femoral-on-Pelvic Flexion/Extension
sagittal plane, 120 degrees flexion and 20 degrees extension, dependent on knee flexion/extension, extension stretches iliofemoral ligament & hip flexors when knee is straight but rectus femoris when knee bent
Femoral-on-Pelvic Abduction/Adduction
frontal plane, 40 degrees abduction limited by pubofemoral ligament, add. muscles, hamstrings and 25 degrees adduction limited by abd. muscles, IT band, superior fibers of the ischiofemoral ligament
Femoral-on-Pelvic Internal/External Rotation
horizontal plane, 35 degrees internal rotation limited by ischiofemoral ligament and ER muscles and 45 degrees external rotation limited by iliofemoral ligament
Describe ipsidirectional lumbopelvic rhythm.
lumbar spine and pelvis rotate in the same direction, amplifying overall trunk motion and maximizing angular displacement for extremity movement
Describe contradirectional lumbopelvic rhythm.
lumbar spine and pelvis rotate in opposite directions, important for postural reactions, used during walking
Would pelvic-on-femoral osteokinematics assume ipsidirectional or contradirectional lumbopelvic rhythm?
contradirectional lumbopelvic rhythm, in many cases the amount of pelvic-on-femoral rotation is restricted by natural limitations of movement within the lumbar spine
Pelvic-on-Femoral Sagittal Plane Movement
flexion - anterior pelvic tilt (taut biceps femoris), extension - posterior pelvic tilt (taut iliofemoral ligament and rectus femoris)
Pelvic-on-Femoral Frontal Plane Movement
abduction (taut intertransverse, pubofemoral ligaments and add. muscles) and adduction (taut intertransverse ligament, piriformis, TFL, IT)
Pelvic-on-Femoral Horizontal Plane Movement
internal and external rotation, about 15 degrees each way
Arthrokinematics of the Hip (Paths for Hip Motion)
abduction/adduction - longitudinal diameter of joint surfaces; internal/external rotation - transverse diameter of joint surfaces (with hip extended); flexion/extension - spin
Which muscles are innervated by the lumbar plexus?
anterior and medial thigh, including quadriceps femoris
Which muscles are innervated by the sacral plexus?
posterior and lateral hip, posterior thigh, and entire lower leg
Which roots form the lumbar plexus?
ventral rami of spinal nerve roots T12-L4
What are the two primary nerve branches from the lumbar plexus and what are their roots?
femoral nerve and obturator nerve, both nerves are formed from L2-L4 nerve roots
Which muscles receive motor innervation from the femoral nerve?
hip flexors, knee extensors, sartorius and part of pectineus
What is the sensory distribution of the femoral nerve?
anterior-medial thigh via anterior femoral cutaneous nerve and anterior-medial lower leg via saphenous cutaneous nerve
Describe the motor and sensory aspects of the obturator nerve.
motor - hip adductors; sensory - medial thigh
Where does the obturator nerve split into anterior and posterior branches?
obturator foramen
Which nerve roots form the sacral plexus?
ventral rami of L4-S4 spinal nerve roots
Through what do most nerves from the sacral plexus exit the pelvis and which muscles are innervated (in general)?
greater sciatic foramen, posterior hip musculature
What nerves make up the sacral plexus?
3 nerves that innervate ER musculature (nerve by name), superior gluteal nerve (glut. med. and min.), inferior gluteal nerve (glut. max.), sciatic nerve
Sciatic Nerve
widest and longest in the body, exits pelvis through greater sciatic foramen inferior to piriformis, consists of tibial nerve and common peroneal nerve (division can occur in different locations)
Why would children complaining of knee pain actually have a hip pathology?
hip capsule receives sensory innervation by the same nerve roots that supply the overlying muscles, anterior capsule receives fibers from femoral nerve while medial aspect of hip and knee receive fibers from obturator nerve
What are two considerations for muscular function at the hip?
1) line-of-force of each muscle does not represent a force vector, only the overall direction of muscle force 2) line-of-force and subsequent lengths of the moment arms apply only to anatomic position
What are the primary hip flexor muscles?
iliopsoas - iliacus and psoas major; primary hip flexor both femoral-on-pelvic and pelvic-on-femoral; iliacus - anterior tilting pelvis and can accentuate lumbar lordosis without ab stabilizing; psoas major - vertical stability to the lumbar spine
Name the hip flexor muscles.
iliopsoas, sartorius, tensor fascia latae, rectus femoris, pectineus, adductor longus
Sartorius
originates at the ASIS, combined action of hip flexion, external rotation, abduction
Tensor Fascia Latae
attaches to the ilium just lateral to sartorius, short muscle that attaches distally to proximal IT band, primary flexor and abductor secondary internal rotator
Rectus Femoris
two joint muscle, 1/3 of total isometric flexor torque at hip, primary knee extensor
Describe the pelvic-on-femoral hip flexion resulting in anterior pelvic tilt.
force-couple between hip flexors and low back extensors, increase in lordosis at lumbar spine, increases compression on lumbar apophyseal joints (normal lordosis optimizes alignment of entire spine)
Which muscles are synergistic with hip flexors during femoral-on-pelvic hip flexion and what would result if these muscles were weak?
abdominal muscles, anterior pelvic tilt and then increased lumbar lordosis will occur if abdominals do not stabilize and initiate posterior pelvic tilt so hip flexors can initiate flexion
Which muscles would fire to prevent further hip flexion if the psoas major were tight (hip flexion contracture on biomechanics of standing)?
gluteus maximus, adductor magnus, hamstrings
List primary hip adductors.
pectineus, adductor longus, gracilis, adductor brevis, adductor magnus
List secondary hip adductors.
biceps femoris, gluteus maximus (inferior fibers), quadratus femoris
Which muscles compose the superficial, middle, and deep layers of hip adductors?
superficial - pectineus, gracilis, adductor longus; middle - adductor brevis; deep - adductor magnus (anterior and posterior heads)
What is unique about the adductor longus muscle?
can be extensor (when hip flexed) or flexor (when hip extended) based on the position of the hip in addition to its primary movement of adduction
Which muscles are primarily responsible for hip internal rotation (anatomic position)?
anterior fibers of gluteus med. and min., adductors, and TFL (no primary hip internal rotators exist)
How is internal rotation affected by flexing the hip to 90 degrees?
internal rotation torque potential of the internal rotator muscles dramatically increases (50%), several external rotator muscles switch (piriformis), angle of insertion changes to near 90 degrees
How do the hip internal rotators function while walking?
rotate the pelvis in the horizontal plane over a relatively fixed femur during stance phase
Name the primary hip extensor muscles.
gluteus maximus, hamstrings, posterior head of the adductor magnus
Name the secondary hip extensor muscles.
posterior fibers of gluteus medius, adductor muscles (only when hip is flexed beyond 50-60 degrees)
At 75 degrees of hip flexion, which muscles would account for 90% of the total extensor torque potential at the hip?
hamstrings and adductor magnus
Describe the motion involved with posterior pelvic tilt (which muscles function in the force-couple).
hip extensor and abdominal muscles act in force-couple (pelvic-on-femoral hip extension), causes a decreased lumbar lordosis
Function of Hip Extensors
control forward lean of the body, slightly flexed posture is minimal activation of glut. max. and hamstrings, flexed position has greater hamstring activation, glut. max. relatively low effort throughout
Femoral-on-Pelvic Hip Extension
large extensor torque to accelerate body forward and upward (when flexed hip), adductor muscles assist
List the primary hip abductors.
gluteus medius, gluteus minimus, TFL
List the secondary hip abductors.
piriformis and sartorius
Which muscle has the greatest abductor moment arm?
gluteus medius, 60% of total abductor CSA, anterior fibers internally rotate the hip (slight), posterior fibers extend and externally rotate
How does the function of gluteus minimus differ from medius?
similar but it has the potential for flexion and IR in the anterior fibers
Which muscle is the smallest of the three primary hip abductors?
TFL, 11% of total abductor CSA
What role does hip abduction play in walking?
control of frontal plane stability of the pelvis during walking, stance phase of gait, primarily glut. med., this is case for all WB activities
Approximate Joint Reaction Force Through Hip During Walking
2.4 times BW (up to 5.5 times during running)
In what position would the hip abductors be able to produce the greatest torque?
slight adduction
List the primary hip external rotators.
piriformis, obturator internus, gemellus superior, gemellus inferior, quadratus femoris, gluteus maximus, sartorius
List the secondary hip external rotators.
posterior fibers of the gluteus medius, biceps femoris, obturator externus
Which muscle of the six “short external rotators” is not considered to be a PRIMARY external rotator?
obturator externus, very close to the axis of rotation
How would you stretch the piriformis if the hip were not flexed?
adduction and internal rotation
In which plane of motion is the average maximal-effort torque produced by the muscles of the hip greatest? The least?
greatest in the sagittal plane (extension and flexion), least in the horizontal plane (internal and external rotation)
What two primary factors contribute to hip fractures in elderly?
osteoporosis and increased risk of falling
What are some signs and symptoms of hip osteoarthritis?
pain, synovitis, loss of joint space, muscle atrophy, hypertrophic bone formation, reduced range of motion, abnormal gate
Why would you want a patient with hip issues to use a cane contralateral but carry a load ipsilateral?
this reduces joint forces caused by hip abductor force on the affected hip
Why would a coxa vara or valga procedure be performed?
to improve the congruency of the weight-bearing surfaces of the hip
What are the positive and negative effects of coxa vara?
positive - increased moment arm for hip abductor force, alignment may improve joint stability; negative - increased shear force across femoral neck, decreased functional length of hip abductor muscles
What are the positive and negative effects of coxa valga?
positive - decreases shear force across femoral neck, increased functional length of hip abductor muscles; negative - decreased moment arm for hip abductor force, alignment may favor joint dislocation
The knee consists of which joints?
lateral and medial compartments of the tibiofemoral joint and the patellofemoral joint
What is more responsible for the stability of the knee: soft-tissue constraints or bony configuration?
soft-tissue constraints (ligaments, joint capsule and menisci, large muscles)
What forms the passageway for the cruciate ligaments of the knee?
intercondylar notch
What structures attach to the head of the fibula?
LCL and biceps femoris
Why is a fracture of the fibula not as problematic?
fibula has no direct function at the knee, only accepts minimal weight (10%)
Describe the surface of the tibia plateau (medial and lateral condyles).
medial slightly concave and lateral slightly convex BUT menisci make both surfaces concave
What attaches to the apex of the patella?
patella tendon (distal point)
What does the articular surface of the patella contact?
intercondylar groove of the femur (patellofemoral joint)
Describe normal genu valgum.
knee forms an angle on its lateral side of about 170 to 175 degrees due to medial angulation of the femur (125 degree angle of inclination of the femur)
Composition of the Anterior Capsule of the Knee
quadriceps muscle, patellar tendon, patellar retinacular fibers
Composition of the Lateral Capsule of the Knee
LCL (outside joint), lateral patellar retinacular fibers, iliotibial tract, biceps femoris, popliteus, lateral head of the gastrocnemius
Composition of the Posterior Capsule of the Knee
oblique popliteal ligament, arcuate popliteal ligament, popliteus, gastrocnemius, hamstring muscles especially through tendon of semimembranosus tendon (muscles and the posterior capsule ligament hyperextension)
Describe excessive frontal plane deviation of the knee.
excessive genu valgum - knock-knee (180 degrees)
Composition of the Posterior-Lateral Knee Capsule
arcuate ligament, LCL, tendon of the popliteus muscle (often referred to as a whole as the arcuate complex)
Composition of the Medial Capsule of the Knee
MCL, medial patellar retinacular fibers, expansions from the tendon of the semimembranosus, further reinforced by the tendons of the sartorius, gracilis, and semitendinosus (pes anserinus)
The knee has as many as ___ bursae and are often associated with ____ _____. They may be formed external to the capsule.
14, fat pads
Incomplete reabsorption of mesenchymal tissues during embryonic development of the knee result in the formation of what structure? Where are their three primary locations?
plica; superior, inferior, medial
The tibiofemoral joint is not very congruous in terms of fit; which structures provide support in the knee?
muscular control, ligamentous support, menisci, capsule
Describe the basic anatomy of the menisci.
crescent-shaped, fibrocartilagenous discs, attached to tibia and adjacent capsule by coronary ligaments, quadriceps and semimembranosus attach to both menisci while popliteus attaches to lateral menisci
Explain blood supply to the mensici.
greatest near the peripheral border, blood comes from the capillaries located within the adjacent synovial membrane and capsule, internal border is essentially avascular
What is the basic shape of the menisci?
medial mensicus - oval or C shape, external border attaches to the deep surface of the MCL and capsule; lateral meniscus - circular or O shape, external border attaching only to lateral capsule, tendon of popliteus passes between LCL and external border of lateral meniscus
The lateral meniscus also attaches to the femur via the _______ ____________ ligament (ligament of Wrisberg).
posterior meniscofemoral
List the functions of the menisci.
reduce the compressive stress at the tibiofemoral joint (primary - occurs through force distribution), stabilizing the joint during motion, lubricating the articular cartilage, reducing friction, guiding the knee’s arthrokinematics
True or false. The coronary ligaments are relatively loose, thereby allowing the menisci to pivot freely during movement.
True, especially the lateral meniscus
What is the primary mechanism through which the mensici reduce pressure on the articular cartilage (compression forces at the knee joint routinely reach approx. 2-3x body weight)?
increasing area of joint contact by deforming peripherally as they are compressed at every step
Osteokinematics of Tibiofemoral Joint
2 degrees of freedom, IR and ER only when flexed; motion is described as tibial-on-femoral or femoral-on-tibial
Knee Flexion and Extension in the Sagittal Plane
5-10 degrees of extension beyond the 0 degree position, 140 degrees of flexion; medial-lateral axis of rotation
During internal and external rotation of the knee, the rotating femur moves in the _______ direction of the knee rotation.
opposite, ex. external rotation of the knee occurs by internal rotation of the femur and vice versa
What is “the evolute?”
flexing knee generates a migrating medial-lateral axis of rotation; migrates with the femoral condyles
What is the biomechanical and clinical implication of the migrating axis of rotation?
alters the length of the internal moment arm of the flexor and extensor muscles of the knee (maximal effort torque varies across ROM), many external devices that attach to the knee rotate about a fixed axis of rotation but care must be taken to align the fixed axis closest to the average axis of rotation which is closest to the lateral epicondyle of the femur
Internal and External (Axial) Rotation of the Knee
vertical axis of rotation, freedom increases with knee flexion, external rotation exceeds internal rotation 2:1
In full extension, describe axial rotation of the knee.
essentially absent as it is blocked by passive tension in the stretched ligaments and the increased bone congruity within the joint
Arthrokinematics at the Tibiofemoral Joint
tibial-on-femoral extension - concave tibia on convex femoral condyles (roll and slide same direction); femoral-on-tibial extension - femoral condyles roll anteriorly and slide posteriorly on the tibia
Describe the “screw-home” rotation of the knee.
locking the knee in full extension requires 10 degrees of external rotation, observable twisting during the last 30 degrees of extension, rotation is mechanically linked and cannot be performed independently
What is the difference between open and closed chain in regards to “screw-home” rotation of the knee.
open chain - tibia externally rotates on fixed femur; closed chain - femur internally rotates on fixed tibia
What are the driving factors “screw-home” rotation of the knee?
shape of the femoral condyle (most important factor), passive tension in the ACL, lateral pull of the quadriceps muscle
During active knee flexion, what action is primarily responsible for “unlocking” the fully extended knee?
popliteus muscle; rotates the femur externally to initiate femoral-on-tibial flexion, rotates the tibia internally to initiate tibial-on-femoral flexion
Flexed Knee Arthrokinematics of Internal and External Rotation
spin between menisci and articular surfaces of tibia and femur, menisci to deform slightly as they are compressed between spinning femoral condyles, menisci stabilized by connections from active musculature (popliteus and semimembranosus)
What stabilizes the patellofemoral joint?
quadriceps muscle, articular joint surfaces, retinacular fibers stabilize the joint
PF Joint Kinematics at 135 degrees of Flexion
patella contacts femur near its superior pole, patella bridges the intercondylar notch of the femur, lateral edge of the lateral facet and the “odd” facet of the patella share articular contact with the femur
PF Joint Kinematics at 90 Degrees of Flexion
contact region migrates inferiorly
PF Joint Kinematics between 90 and 60 degrees of flexion
greatest contact area is present (still only about 30% of the total surface area of the patella)
PF Joint Kinematics in last 20 degrees of flexion
contact point of patella migrates to inferior pole
Location of patella in full extension
rests completely above the intercondylar groove, against the suprapatellar fat pad
Describe the MCL.
very vascular; flat, broad structure that spans medial side of the joint; anterior part is larger and blends with the medial patellar retinacular fibers before attaching to the medial-proximal aspect of the tibia; posterior part is short set of fibers with distal attachments to the posterior-medial joint capsule, medial meniscus, and tendon of the semimembranosus muscle
Describe the LCL.
vascular; round, strong cord that runs nearly vertical between the lateral epicondyle of the femur to the head of the fibula (does not attach to the adjacent meniscus)
Collateral Ligament Function
primary - limit excessive motion in the frontal plane, MCL resists valgus stress, LCL resists varus stress; secondary - limit extremes of knee extension (shared with posterior capsule, oblique popliteal ligament, knee flexor muscles, and ACL)
What is the primary restraint of valgus force at the knee?
MCL, especially superficial fibers
What is the primary restraint of varus force at the knee?
LCL
Which structure would likely be damaged by forceful posterior translation of the tibia i.e. “dashboard” injury?
PCL
Most fibers of this ligament resist extension in the knee.
ACL
Most fibers of this structure resist knee flexion.
PCL
These ligaments resist extremes of knee valgus, varus, and axial rotation (most resistant to anterior-posterior shear forces).
ACL and PCL
Describe the location of the ACL.
from distal attachment, runs from anterior intercondylar area of tibial plateau obliquely in a posterior, slightly superior, and lateral direction to attach on the medial side of the lateral femoral condyle (posterior-lateral bundle is main component of ACL)
When do most fibers of the ACL become taut?
as the knee approaches full extension
Which structures help stabilize the extended or near-extended knee?
posterior capsule, collateral ligaments, hamstring muscles, ACL
Why would the manual test for ACL integrity (anterior drawer test) not be the most sensitive to determine ACL injury?
secondary restraints such as the posterior capsule, collateral ligaments, flexor muscles (spasm in hamstring muscles)
The oblique manner in which the ACL courses through the knee allows it to resist the extremes of _____ movements.
ALL
Common mechanism for ACL injury?
excessive hypertension of the knee with foot planted, frequently involves trauma to the collateral ligaments and the posterior capsule
Severe valgus force can result in an “unhappy triad” involving which structures?
MCL, ACL, medial meniscus
Describe the location of the PCL.
courses from posterior intercondylar area to the lateral side of medial femoral condyle, 2 bundles, thicker than ACL
Which muscles pull the PCL taut and which muscles slacken the PCL?
taut - hamstring contraction; slacken - quadriceps contraction
What test is used for the PCL?
posterior drawer, PCL limits anterior translation of the femur over the fixed tibia
PCL Injury
incidence 5-20% of ligamentous knee injuries, often associated with injuries to other structures, patellofemoral tendinitis, hyperflexion, hyperextension
Which muscles account for 80% of the total extension torque in the knee?
vasti
How does the patella contribute to knee extension leverage?
anterior displacement of the quad tendon/patella tendon increases internal moment arm to enhance torque potential
Describe the difference in internal torque potential in tibial-on-femoral versus femoral-on-tibial extension.
tibial-on-femoral - increasing demand on quadriceps approaching full extension; femoral-on-tibial - decreasing demand on quadriceps approaching full extension
When is the knee extension torque potential greatest?
between 45-60 degrees of flexion (extension torque influenced by both internal moment arm and muscle length)
In regards to the patellofemoral joint, how does a deep squat compare to climbing stairs?
3.3x body weight climbing stairs vs. 7.8x body weight during deep squat, increased angle results in increased resultant joint forces, force and contact area greatest within PF joint at 60-90 degrees
A Q-angle greater than ___ degrees increases _______ pull of the patella.
15, lateral
Which structures guide patellofemoral tracking?
quadriceps muscle (superior and lateral), quad tendon (lateral bias), vastus medialis oblique, retinacular fibers (medial and lateral), lateral femoral condyle (raised - resists lateral)
Which structures contribute to lateral directed forces of the patella?
iliotibial band, lateral patellar retinacular fibers (bowstringing force of the patella caused by pull of quadriceps and patellar tendons)
Which structures contribute to medial directed force of the patella?
vastus medialis (oblique fibers), raised lateral facet of the intercondylar groove, medial patellar retinacular fibers
What movements would increase the lateral bowstringing of the patella?
excessive knee external rotation and valgus
When reaching around to catch a ball (figure 13-32 pg. 551), the right knee acts as an important pivot point. Which structures accelerate and decelerate the external rotation of the knee?
decelerators - pes anserinus muscles, stretched MCL and oblique popliteal ligament; accelerator - short head of biceps femoris
Which muscles contribute to flexion and medial rotation of the knee?
semimembranosus, semitendinosus, sartorius, gracilis
Which muscles contribute to flexion and lateral rotation of the knee?
biceps femoris
Where is the maximal torque production potential greatest for the knee flexors?
greatest near full extension although internal moment arm greatest at 45 degrees, length-tension relationship is most influential rather than internal moment arm
Describe the location of the popliteus muscle.
attachment to lateral condyle of the femur between LCL and lateral meniscus, fibers attach to lateral meniscus and blend with arcuate popliteal ligament
Knee Extensor to Flexor Peak Torque Ratios
extensors 2/3 greater than flexors, decreases as speed of contraction increases
Describe control of tibial-on-femoral extension during running.
tibia deceleration, dampen impact of full knee extension at end of swing phase, shorten limb to swing during running
During walking, greater compression force is generated over the ______ articular surface of the knee.
medial
During excessive genu varum, excessive forces pass through the ______ compartment of the knee.
medial
Excessive genu valgum will result in excessive compressive forces on the _______ compartment of the knee.
lateral (associated with coxa vara)
What is genu recurvatum?
> 10 degrees hyperextension, results in weak hip flexors, weak quadriceps, overstretched posterior capsule and paralyzed knee flexors
What is the significance and primary function of the foot and ankle?
shock absorption and propulsion; importance in weight bearing, gait, and function; needs pliability but also rigidity and abnormalities will lead to multiple problems up the kinetic chain
What joint is primarily associated with the ankle?
talocrural joint
What joint is associated with the rearfoot?
subtalar joint
The fibula articulates with the tibia distally on what triangular concavity?
fibular notch
What is the result of lateral tibial torsion and how much is normal?
foot is in slight external rotation (toe out); 20-30 degrees (excessive could contribute to knee injuries)
What is the significance of the talus?
primary weight acceptor, articulates with calcaneus (subtalar joint), trochlear surface is site of articulation with tibia (talocrural joint)
What bone is the largest tarsal bone?
calcaneus
What site serves as the attachment site for the Achilles tendon?
calcaneal tuberosity (medial and lateral process - plantar fascia attach)
What is the sinus tarsi?
sulci formation from talus and calcaneus on lateral side of subtalar joint
What is sustentaculum tali?
shelf for the talus, medial side of subtalar joint
What bones articulate with the navicular?
concave proximal to articulate with head of the talus, flat distal to articulate with cuneiforms
What is the significance of the navicular tuberosity?
medial tubercle, attachment of posterior tibialis, “keystone to the arch,” navicular tuberosity drop may be associated with many types of injuries such as ACL tears
What contributes to the convexity of the dorsum of the foot (transverse arch)?
cuneiforms, distal to navicular
What does the cuboid articulate with?
calcaneus, lateral cuneiform, 4th and 5th metatarsals
The plantar surface of the cuboid has a groove for which muscle’s tendon?
peroneus longus
What are the major joints of the foot and ankle?
talocrural, subtalar, transverse tarsal; talus is important - involved in all three joints, 70% covered with articular cartilage
How many degrees of freedom in the ankle?
3; DF and PF in sagittal, inversion and eversion in frontal, abduction and adduction in horizontal
Describe the axis of rotation of the ankle.
oblique axis of rotation, all movements perpendicular to this axis
What movements are associated with pronation?
abduction, eversion, dorsiflexion
What movements are associated with supination?
adduction, inversion, plantarflexion
Describe the proximal tibiofibular joint.
head of fibula and posterior-lateral aspect of lateral condyle of the tibia, capsular ligaments transfer force of biceps femoris and LCL to tibia
Describe the distal tibiofibular joint.
convex medial distal fibula and concave fibular notch of tibia
Which ligaments contribute to the support of the tibiofibular joints?
interosseous, anterior and posterior distal tibiofibular ligaments
Explain the structure of the talocrural joint.
convex trochlea of the talus articulates with concavity formed by tibia and medial and lateral malleolus, ankle “mortise”
On the medial side of the ankle, which ligament provides support and what are the major bundles?
deltoid ligament; tibionavicular attaches to navicular tuberosity, tibiocalcaneal attaches to sustentaculum tali, tibiotalar attaches to medial tubercle and side of talus (not often injured)
Name the lateral ligaments of the ankle.
anterior talofibular (ATF), calcaneofibular (CF), posterior talofibular (PTF)
Which ligament of the ankle is most commonly injured?
ATFL (inversion or adduction with plantarflexion)
Which movements would contribute to injury of the CFL?
inversion with dorsiflexion
The primary function of this ligament is to stabilize the talus within the mortise, and limit abduction of talus when DF.
PTFL
Anterior translation of the talus stresses which ligaments of the ankle?
deltoid (tibionavicular) and anterior talofibular (ATF)
Osteokinematics of the Talocrural Joint
1 degree of freedom, axis through body of talus and tips of both malleoli, DF associated with slight abduction and eversion, PF associated with slight adduction and inversion
Posterior translation of the talus stresses which ligaments of the ankle?
deltoid (tibiotalar), calcaneofibular (CF), posterior talofibular (PTF)
Arthrokinematics of Dorsiflexion of Talocrural Joint
convex talus rolls forward and slides posterior, ligaments that resist posterior translation become taut with full dorsiflexion (deltoid - tibiotalar, CF, PTF)
Arthrokinematics of Plantarflexion of Talocrural Joint
convex talus rolls backward and slides anterior, ligaments that resist anterior translation become taut with full plantarflexion (deltoid - tibionavicular, ATF)
Talocrural Joint and Stabilization During Gait
dorsiflexion occurs near end range of heel-off - increased stability, tension of overstretched ligaments and PF muscles, tight congruency of talus in mortise, concavity of mortise spreads out with superior migration of fibula and external rotation
While going from squatting to standing, what motion occurs at the ankle and what is the arthrokinematics?
plantarflexion, concave tibia rolls and slides anterior on convex talus at talocrural joint
Describe what occurs during full dorsiflexion.
widening of mortise, superior glide of fibula and slight external rotation, stress up to proximal tibiofibular joint, stress on distal tibiofibular ligament (high ankle sprain), stress on interosseous membrane
Which movement would be associated with high ankle sprains?
forced, full dorsiflexion
Explain what occurs with full plantarflexion.
loose pack position, decreased tension of mortise, unstable/susceptible to injury
What is responsible for the strongest bond between talus and calcaneus?
interosseous and cervical ligaments (located deep in tarsal sulcus)
At the subtalar joint, which ligaments limit inversion?
cervical and calcaneofibular
At the subtalar joint, which ligaments limit eversion?
talocalcaneal and tibiocalcaneal (deltoid)
Kinematics of Subtalar Joint
arthrokinematics - sliding between three facets; osteokinematics - two degrees of freedom (inversion/eversion and abduction/adduction)
Explain closed pack position of the subtalar joint.
full supination, inversion of calcaneus causes talonavicular joint and calcaneocuboid joint “twist,” increased rigidity not joint congruency
What is open pack position of the subtalar joint?
full pronation, eversion of calcaneus results in parallel orientation of midfoot
Explain subtalar neutral position.
baseline position or neutral measure of position of subtalar joint, position aligns both sides of talus equally within mortise (1/3 from full eversion)
What is the significance of the transverse tarsal joint and what two articulations compose it.
allows foot to adapt to surface contours (pronation and supination), works in conjunction with subtalar joint; talonavicular (proximal medial), calcaneocuboid (proximal lateral)
Talonavicular Joint
convex head of talus and concave proximal navicular (anterior joint)
Calcaneonavicular Ligament (Spring)
floor of talonavicular joint, attach sustentaculum tali (calcaneus) to plantar surface of navicular, contributes to stability of head of talus and prevents dropping with weight bearing (keep arch upward)
Which ligaments stabilize the talonavicular joint?
posterior - interosseous ligament, dorsal - dorsal talonavicular ligament, lateral - calcaneonavicular fibers of bifurcated ligament, medial - anterior edge of deltoid ligament (twisting effect of midfoot due to ball-in-socket like articulation)
Which ligaments stabilize calcaneocuboid joint?
dorsal calcaneocuboid ligament, lateral part of bifurcate ligament, long and short plantar ligament
Kinematics of Transverse Tarsal Joint
pronation and supination; if calcaneus fixed most motion will occur through mid foot but if calcaneus free most will occur through summation of rear foot and mid foot
Arthrokinematics of Midfoot
pivoting of navicular with supination/pronation (posterior tibialis supinates and peroneus longus pronates), concave navicular spins on talus
Medial Longitudinal Arch of Foot
concave in-step at medial side of foot, keystone located near the talonavicular joint, primary load-bearing and shock absorption structure
Which structures contribute to height and shape of the medial longitudinal arch?
plantar fascia, spring ligament, stability of medial tarsometatarsal joints, short plantar ligament, muscles of the foot
Toe extension stretches ______ _____ and increases tension in medial longitudinal arch.
central band
What is significant about the plantar fascia?
provides primary support for the arch, central fibers are the main portion, cover MTP joints and sheaths and flexor tendons of digits
Explain the passive support in the medial longitudinal arch.
body weight distributed across MLA and to fat pads and thick dermis at heel and ball of foot; weight depresses talus inferior and flattens MLA, tension in deep plantar fascia, rearfoot pronates slightly (calcaneus everts/valgus position), posteror tibialis and intrinsic muscles are activated
Pes Planus
flat foot, plantar fascia overstretched, subtalar joint pronated, rearfoot valgus, decreased ability to transfer loads, intrinsic and extrinsic muscles activate to compensate for lack of ligament support
What is the difference between rigid and flexible pes planus?
rigid - dropped arch whether weight bearing or not (congenital); flexible - arch appears normal until weight bearing (more common, acquired, associated with other conditions and overuse injuries)
Pes Cavus
abnormally raised arch, metatarsal heads more perpendicular to ground, callus formation, claw toes, tight plantar fascia
Explain movement at the subtalar joint during the stance phase of walking.
during early stance (30%), subtalar joint pronates (everts) to allow flexibility, late stance it inverts (supinates) to create rigidity in midfoot and prepare for pushoff
What movements are associated with pronation immediately after heel strike during walking?
calcaneus everts due to ground reaction forces, head of talus pushed medially and inferior, contact with ground results in dorsiflexion with subtalar abduction = pronation, internal rotation of femur and tibia/fibula steers subtalar joint into further pronation
Which muscle is eccentrically activated during normal pronation which dissipates IR of femur and lower leg during early stance phase of gait?
tibialis posterior
Which joints transfer pronation/supination through medial midfoot to forefoot?
cuneonavicular joints
What occurs during mid-to-late stance (supination)?
20% into gait cycle, stance limb reverts back to ER, pronated (everted) subtalar joint gradually starts to supinate at about 30-35% into cycle, by late stance the full supination and elevated arch convert midfoot into rigid lever
Which joints form the transverse arch of the midfoot?
intercuneiform and cuneocuboid joints (weight distribution to metatarsal heads)
Why would navicular drop contribute to ACL tears?
increased pronation linked to increased IR torsion leading to potential increased stress on knee
Which ray is the central pillar?
2nd
What is unique about the 1st MTP?
sesmoid bones imbedded in flexor hallicus brevis
MTP Joint Surfaces
convex head of metatarsal and concave proximal end of proximal phalanx
MTP Joint Kinematics
2 DOf, flexion/extension and abduction/adduction, pushoff with walking = 65-85 degrees of hyperextension (flexion 30-40 degrees)
Hallux Rigidus
osteophytes may limit hyperextension and interfere with push-off
Hallux Valgus
lateral deviation of the first toe, excessive adduction of the first TMT, proximal phalanx abducts and rotates, medial collateral ligament at MTP fails, weight bearing avoided at first ray
At the IP joints of the foot, which motion exceeds (flexion or extension)?
flexion (extension limited by flexor muscles and plantar ligaments)
What is the Windlass Effect?
hyperextension of MTP stretches plantar fascia within MLA and stabilizes the midfoot and forefoot for push-off (primary mechanism used to lift the arch)
Learn the muscles in the “muscles” folder.
The link is on facebook or ask Kaley, she is better at those things.
Lateral Compartment and Gait
most active through mid to late stance, decelerate supination of subtalar, neutralize inversion bias of PF
When raising up on your toes, which muscles’ actions provide a sling support of MLA and transverse arch?
peroneus longus and tibialis posterior
What is in the tarsal tunnel?
tibialis posterior, flexor digitorum longus, flexor hallicus longus, posterior tibial artery and nerve
Plantarflexion is typically associated with supination, but which two muscles contribute to PF and NOT supination?
peroneus longus and brevis
The torque of which motion exceeds max torque of all other motions of the ankle COMBINED.
PF
Why could closed chain dorsiflexion cause knee flexion?
if soleus is weak and is unable to decelerate ankle dorsiflexion shifts body weight and buckles knee
Pes Equinovarus
shortening of gastrocnemius, soleus, posterior tibialis (injury to common branch of peroneal nerve - paralysis of EV and DF)
Injury to deep branch of peroneal nerve could result in what abnormality?
foot drop (DF muscles)
Injury to the superficial branch of the peroneal nerve could result in what abnormality?
pes varus (EV muscles)
Injury to tibial nerve could result in what?
pes calcaneus and pes calcaneovalgus
Plantar Layer 1
flexor digitorum brevis, abductor hallucis, abductor digiti minimi
Plantar Layer 2
quadratus plantae, lumbricals
Plantar Layer 3
adductor hallucis, flexor hallucis brevis, flexor digiti minimi
Plantar Layer 4
plantar and dorsal interossei
In sprinting, as the individual pushes off (plantar flexion), how is over stretching prevented?
knee extension (gastroc lengthening) occurring simultaneous to plantar flexion prevents over shortening and allows large torque through great range of motion
