Exam 4: Hip (Biomech) Flashcards

between femoral head and acetabulum

stability

large torques to generate ambulation/movement

• union of 3 bones: ilium, pubis, ischium

• 3 noticeable features:
  • iliac fossa (iliac muscle attachment)
  • articular surface (articulate w/ sacrum @sacroliac joint)
  • iliac tuberosity (sacroiliac ligament attachment)

• pubic crest (upper part+attach with rectus abdominus muscle))
• pubic tubercle (inguinal ligament attachment)
• inferior pubic ramus (body to ischium junction)
• pubic symphysis joint+disk (midline of 2 pubic bones)
• interpubic disc (p. symp joint bounding)

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• very stable // force transmission // giant pressure, fitting ring
• ischial spine (BEHIND + ischium + below greater SN)
• lesser sciatic notch (below spine)
• lesser sciatic foramen (sacrospinous + sacrotuberous ligament)
• ischial tuberosity (attachment for hamstrings/adductor magnus)
• ischial ramus

• deep, circular socket (ilium + ischium= 75%, pubis = 25%)(little vinegar cup)

• longest + strongest bone in body
• force travels up the head //allowing for a deep socket cover
• angle = where ground reaction goes
• shaft = bowing with body weight,
  • compressed (along post, shaft)
  • tension (along ant. shaft)
• lesser trochanter: post-medial direction, distal attachment for iliopsoas muscle (hip flexor+vertical stabilizer)

• normal (125 degrees)
• coxa vara (105 degrees)
  • bowing in legs
• coxa valga (140 degrees)
  • bowing in legs
  • in childhood from crawling

• EX. ant: in kids // 35 degrees
• pigeon walking
• femur tilt forward (affects hips) // "in-toeing" improves joint congruity

• normal ant (15 degrees_)
• excessive ant (35 degrees)
• retroversion (15 degrees)

• boney anatomy: resist/counterforce
• tension+compression+shear tension => VERY DYNAMIC SYSTEM
• compact + TROCHLEAR bone: thick sides resist tension + shear

• 2/3 of a perfect sphere
• increased blood flow in children
• ligament teres (ligament to head of femur)
• fovea: prominent pit

• horseshoe shape represents THICKNESS
  • top = more cartilage (x3.5 more thicker)
  • bottom = less cartilage

• deep in socket (additional labrum) = adds 30% of depth
• very hard to dislocate hips = strong vacuum mechanism (negative pressure), grips femoral head in socket
• poorly vascularized: slow healing

• central edge angle = 35 degrees
  • how much acetabulum covers the femoral head, good for stable + mobility
• LOW (<35 degrees) = less acetabulum cover, 50% less joint pressure, premature degeneration/osteoarthritis
• HIGH (>35 degrees) = more ACT. cover+stable, lead to impingement/injury, can't sit down

• angle = 20 degrees
• anterior to posterior coverage
• back cover = deeper (squat

• nature's duct tape (giant ball of leather)
• lots of stuff = had to dislocate

• end range position + taut tissue
  • hip flexion (knee extended) => hamstring

• most stable passive position
• taut structures: ischiofemoral ligament, iliofemoral ligament, pubofemoral ligament
  • ischiofemoral ligament: extension + internal rotation
  • iliofemoral ligament: extension
  • pubofemoral ligament: extension and abduction

• extension + flexion
  • (TOP = P.on.F)(BOT= F.on.P)
• abduction + adduction
  • (TOP = P.on.F)(BOT= F.on.P)
• ext. rotation + ir. rotation
  • (BACK = P.on.F)(FRONT = F.on.P)

• femoral on pelvic hip rotation
• leg up (120 degrees)
• leg back (20 degrees)

• abduction // leg out to side (40 degrees)
• adduction // leg in (25 degrees)

• internal rotation // foot in (35 degrees)
  • piriformis // ischiofemoral ligament
• external rot // foot out (45 degrees)
  • pubofemoral + lliofemoral ligament

• pelvic on femoral hip rotation
• flexion (ant. pelvic tilt) // straighten back
  • slack iliofemoral ligament (30 degrees) + biceps femoris
• extension (post. pelvic tilt)
  • lliofemoral ligament (15 degrees) + rectus femoris

• abduction // leg weight shift out (30 degrees)
  • intertransverse ligament (in), pubofemoral lig (out), adductor brevis (out) // adductor longus (out + down)
• adduction // leg weight shift in(25 degrees)
  • intertransverse ligament (out+down), piriformis (out+down),tensor fasciae latae + iliotibial band(out + down)

• internal rotation // lean forward (15 degrees)
• external rot // lean backward (15 degrees)

• "ipsidirectional" // bend forward // flexion
  • TOGETHER = lumbar spine + pelvis rotate
• "contradirectional" // bend back // extension
  • OPPOSITE= lumbar spine (back) + pelvis rotate (forward)

• HINGE JOINT
• longitude: abduction and adduction
• transverse: internal + external rotation
• axis of rotation: flexion and extension

• spin foward + spin back

• roll up + slide down

• roll up + slide down

• rectus femoris: straight up (superior)
• illiosas: small mnt arm, UP force b/c beefy
• glute max: UP force // LOW mnt arm
• groups work together: line of pull go across+in front/overlap
• NO force vector force => just angle pull
• mnt arm changes w/ mvt

• primary vs. secondary muscles

• illiosoas: most potent
• sartorius: hacky sack mvt // external rot

• turn on tilt muscles + muscles that keep body foward
• rectus femoris: keeps body stable

• lateral: looking at back side // abduction
• medial: looking at front side// adduction

• Producing force in 3 planes
  • deep layer (anterior head // adductor magnus // posterior head)
  • middle layer (adductor brevis)
  • superficial layer (pectineus // adductor longus // gracillis)
• Adduction longus + hip extension
  • adductor magnus + longus
• adduction longus as hip flexor\
  • adductor longus + rectus femoris

• In the anatomic position, there are NO primary IRs
• external factors = ABOVE axis

• (PRISIFORM)

• lunge w/ foward lean
  • glute prominent
• lunge w/ back lean
  • hamstreing prominent
• SLDL vs. DL
• Posterior chain: all muscles work together // contribution just changes

• jump box squat
• high demand: hip, knee, ankle, low back extensors,

• glute medius
  • 60% of cross-section of all muscles
  • internal + external rot
  • no one muscle directly through point (GRAPH)
    • must have synergy for pure adduction

• counterclockwise: internal torque
  • HAF * D // hip abductor force * moment arm
• clockwise: external torque
  • BW * D1 // body weight * external moment arm

• old people walk = weak glutes
• not use abductors = weak walk
• NORMAL: need to work at 20% of capacity
• T. Sign: lost of 80% of full function

• compress the articular surfaces of the hip joint
• muscles
  • piriformis. // gemellus superior and inferior // obturator internus and externus // quadratus femoris // gluteus maximus

• at rest: 130 degree deflection (pulley through lesser sciatic notch)
• compression force (@joint): muscle contraction

• right external rotator msucles @ pelvis-on-femoral ext. rot of right hip
• back muscles: rot. lower left trunk

1. extensor: most torque @ sagittal plane
   1. good + moving foward (straight line spread) (UP torque)(LOW speed/NOT fast)
2. Flexors @ sagittal plane: counters extensors (isometric)
3. adductors @ frontal plane: help with flex+ ext
4. abductors: keeps pelvis level
5. internal +external rot: not too forceful / horizontal stuff

Pass in front and behind medial lateral axis

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