Functional Anatomy and Biomechanics of Hip and Pelvis Region

Question 1

Introduction

Answer 1

• hip is 2nd largest joint in body
• hip establishes link between LE and trunk: absorbs high forces, supports body’s mass
• LE links with trunk at pelvic girdle
• any movement in trunk pelvis or LE involves/influences hip joint
• important to evaluate movement and actions of both limbs, pelvis, and trunk: rather than to focus on single joint, improves evaluation, treatment, and outcomes
• one area in ____ system with noticeable differences between sexes: female pelvis typically lighter, thinner and wider than in males; this can affect motion in the trunk, pelvis, and LE

Question 2

Osteology

Answer 2

• pelvis: fibrous union of 3 bones
• ilium superior, ischium posteroinferior, pubis anterior inferior
• separate at birth but typically fused by 15-17 years
• proximal femur

Question 3

The Pelvis

Answer 3

• ilium, pubis, and ischium
• right and left sides joint sacrum to form a ring or hoop aka pelvis or pelvic girdle
• connect anteriorly through pubic symphysis
• connect posteriorly through sacrum

Question 4

Ilium

Answer 4

• landmarks of note on external surface: ASIS and AIIS, iliac crest, PSIS and PIIS, greater sciatic notch and greater sciatic foramen
• landmark on ote on internal surface: iliac fossa, auricular surface, iliac tuberosity

Question 5

Pubis

Answer 5

• landmarks of note:
• superior pubic ramus
• body
• pectineal line
• pubic tubercle
• inferior pubic ramus
• symphysis pubis

Question 6

Ischium

Answer 6

• landmarks of note:
• ischial spine
• lesser sciatic notch
• lesser sciatic foramen
• ischial tuberosity
• ischial ramus

Question 7

Acetabulum

Answer 7

• formed at junction of the 3 bones in hip
• located above obturator foramen
• concave joint surface
• joins with femoral head

Question 8

Acetabular Orientation

Answer 8

• center edge angle: aka angle of wilberg 35-50* provides best containment of femoral head
• acetabular anteversion angle ~20* marked variation of this angle can contribute to dislocation

Question 9

Femur

Answer 9

• landmarks of note:
• femoral head
• femoral neck
• intertrochanteric line
• greater trochanter
• lesser trochanter
• intertrochanteric crest
• quadrate tubercle
• linea aspera
• spiral line
• gluteal tuberosity
• adductor tubercle

Question 10

Femoral Angle of Inclination

Answer 10

• measured angle
• between femoral neck and medial side of femoral shaft
• typically ~125* in mature skeleton ~140-150* at birth
• influences: effectiveness of hip abductors, limb length, forces imposed on hip joint
• variations in adulthood: coxa vara (<125) coxa valgus (>125)

Question 11

Femoral Torsion Angle

Answer 11

• another measured angle
• describes the “twist” between femoral neck and femoral shaft
• normal anteversion ~10-15* anterior to frontal plane
• some have structural variation from normal anteversion: may affect individual movement patterns or function
• excessive anteversion ~35* anterior to frontal plane
• retroversion ~0* to frontal plane
• individual may demonstrate some NM compensations for structural variations

Question 12

Key Points on Angle of Inclination/Femoral Torsion

Answer 12

• both identified with diagnosti imaging
• neither can changed by PT in adults
• we can change movement patterns: place less stress on area, better help to compensate for structural variation, etc; strengthen target muscles, stretch target muscles
• important to differentiate things PT can change from those it can’t

Question 13

Pubic Symphysis

Answer 13

• site where right and left sides of pelvis connect
• cartilaginous joint with fibrocartilage joint
• end of each pubis covered with hyaline cartilage
• pubic ligament supports pubic symphysis: anterior, posterior, and superior sides of joint
• limited motion at pubic symphysis

Question 14

Sacroiliac Joint

Answer 14

• connects pelvis to sacrum
• synovial joint with strong ligamentous support
• these ligaments are the strongest in the body
• transmits force between LE and spine
• movement occurs at SI joint: varies considerably between individuals and sexes
• males: have thicker stronger ligaments; 3 of 10 have fused SI joints
• females: have greater ligamentous laxity

Question 15

SI Joint Motion

Answer 15

• sacrum is actually 5 fused vertebrae
• top of sacrum is base
• sacral flexion occurs when base moves anteriorly aka nutation, occurs with lumbar extension
• sacral extension occurs when base moves posteriorly aka counternutation occurs with lumbar flexion
• sacral torsion occurs with rotation of the left and right halves about the medial lateral axis: right rotation occurs if anterior surface of sacrum faces right, left rotation occurs if anterior surface of sacrum faces left

Question 16

Movements of the Pelvis

Answer 16

• described by monitoring ASIS/AIIS
• anterior tilt is forward tilting and downward movement of the pelvis
• occurs when: the trunk flexes as in standing forward bend, sitting with exaggerated lumbar arch
• posterior tilt: occurs when the trunk extends as in standing back bend, sitting in slouched position
• tuck butt (posterior tilt) vs. duck butt (anterior tilt)
• lateral tilt: right or left, aka pelvic obliquity, controlled by muscles
• rotation occurs about longitudinal axis in the horizontal plane
• as R leg swings forward pelvis rotates to the L vice versa when L leg swings forward

Question 17

Hip Joint

Answer 17

• ball and socket joint
• 3 degrees of freedom
• femoral head: 2/3 of a perfect sphere, entire head is covered by cartilage (except fovea)
• ligamentum teres attach fovea to acetabulum
• acetabulum is incomplete near inferior acetabular ligament
• a labrum helps to deepen this joint
• spongy trabecular bone in femoral head and acetabulum helps to absorb forces
• articular cartilage on femoral head is thickest centrally-most load supported here
• 70% of femoral head articulates with acetabulum 25% in glenohumeral joint

Question 18

Ligaments in Hip Joint

Answer 18

• loose but strong capsule surrounds the joint

- reinforced by iliofemoral, pubofemoral, and ischiofemoral ligaments

Question 19

Osteokinematics at Hip Joint

Answer 19

• hip flexion: 120* with flexed knee 80* with extended knee
• hip extension: 20* with extended knee 10* with flexed knee
• hip abduction 40-45*
• hip adduction 25* past midline
• hip internal rotation 35*
• hip external rotation 45*

Question 20

Arthrokinematics at Hip Joint

Answer 20

• joint orientation: acetabulum-anterior, lateral, inferior; femoral head-posterior, medial, superior
• concave surface: acetabulum
• loose-pack position: 30* flexion, 30* abduction, slight LR
• close-pack position: full extension, abduction, and MR
• flexion/extension: spinning, little or no roll or glide
• abduction: upward roll, downward glide
• adduction: downward roll upward glide
• IR: femoral head rolls anteriorly, glides posteriorly
• ER: femoral head rolls posteriorly, glides anteriorly

Question 21

Lumbopelvic Rhythm

Answer 21

• occurs with forward bend
• coordinated movement of pelvis and lumbar spine
• spinal flexion and anterior pelvic tilt

Question 22

Gross Hip ROM and Functional Activities

Answer 22

• 80* flexion/extension needed for stand to sit
• 100* flexion/extension need for sit to stand
• 60* flexion needed to climb a stair
• 24-30* needed for descent of same stair
• during walking 35-40* flexion during late swing, full extension during heel off
• abduction/adduction: most activities require 20* or less, walking requires 12, full squat requires 18-20 abd: tie shoes, etc
• IR/ER: both increase with thigh flexion; full squat requires 10-15* ER, tie shoes etc

Question 23

Innervation in Hip Region

Answer 23

-supplied by lumbosacral plexus

Question 24

Muscular Control of the Pelvic Girdle

Answer 24

• sit of muscular attachment of 28 trunk and thigh muscles: none positioned to act solely on pelvic girdle
• proper positioning of pelvic girdle necessary and thigh necessary for efficient movement

Question 25

Hip Flexors

Answer 25

• primary: iliopsoas, rectus femoris, TFL, sartorius, adductor longus, pectineus
• secondary: adductor brevis, gracilis, gluteus minimus

Question 26

Hip Extensors

Answer 26

• primary: glute max, biceps femoris, semitendinosus, semimembranosus, adductor magnus
• secondary: gluteus medius

Question 27

Hip Abductors

Answer 27

• primary: glute medius, minimus, TFL

- secondary: piriformis, sartorius

Question 28

Hip Adductors

Answer 28

• primary: adductor longus, adductor brevis, pectineus, gracilis, adductor magnus
• secondary: biceps femoris, quadratus femoris, glute max

Question 29

Internal Rotators of Hip

Answer 29

-glute min, med, TFL, adductor longus, adductor brevis, pectineus, semitendinosus, semimembranosus

Question 30

External Rotators of Hip

Answer 30

• primary: glute max, piriformis, obturator internus, gemelli, quadratus femoris, sartorius
• secondary: glute med, min, obturator externus, biceps femoris

Question 31

Muscular Actions in Hip Region-Flexion

Answer 31

• important in activities requiring quick leg action
• elite athletes usually stronger hip flexors and abs
• fatigue may lead to altered running gait, increased risk of injury
• iliopsoas is strongest hip flexor
• contribution of rectus femoris depends on knee joint position

Question 32

Muscular Actions in Hip Region-Extension

Answer 32

• hip mm are strongest in extension
• important supporter of body weight for many functional tasks
• counteracts gravitational pull during walking, running, jumping, etc
• hamstrings contribute to hip extension at all points (can generate more force when knee extended)
• hamstring problems can create postural problems and lessen quality of movement
• glut max recruited if more vigorous action needed-helps to prevent trunk flexion at foot strike
• loss of glut max not as detrimental compared to loss of hamstring

Question 33

Muscular Actions in Hip Region-Abduction

Answer 33

• greatest ABD force at neutral
• important in dance and gymnastic skills
• hip stabilization during gait
• glute med weakens presents as trendelenburg gait
• glute min, TFL, piriformis also contribute

Question 34

Muscular Actions in Hip Region-Adduction

Answer 34

• muscles bring thigh to body’s midline
• collectively form large muscle mass
• also work to maintain stability in frontal plane during gait

Question 35

Muscular Actions in Hip Region-External Rotation

Answer 35

• preparation for power production

- preventing excessive IR during loading response, landing

Question 36

Muscular Actions in Hip Region-Internal Rotation

Answer 36

-weakest of hip motions

Question 37

Therapeutic Exercise for Hip Region

Answer 37

• complete isolation specific muscle very difficult
• secondary to many LE muscles work in combo functionally
• modify modify modify

Question 38

Contusions in Hip Region

Answer 38

• MOI: blunt trauma
• common at iliac crest, buttocks, femoral triangle, trochanter
• clinical presentation: antalgic gait, ecchymosis, loss of ROM secondary to pain, palpation painful to specific tissues

Question 39

Groin Strain

Answer 39

• may involve many tissues
• common
• attachment of iliopsoas at l trochanter common site
• hx: often related to extension force to thigh
• common findings: ROM often painful with IR and/or with passive extension; resisted is painful with hip flexion

Question 40

Bursitis in Hip Region

Answer 40

• many bursa located here
• commonly seen in PT…
• trochanteric bursitis-under glut max over trochanter
• iliopectineal bursitis-under iliopsoas, over anterior ligaments
• ischial gluteal bursitis-may be caused by prolonged sitting

Question 41

DJD in Hip

Answer 41

• osteoarthritis
• common condition secondary to wt bearing stress
• leads to deterioration of articular cartilage, overgrowth of periarticular bone
• x-rays show decreased joint space and osteophytes

Question 42

Pelvic Fractures

Answer 42

• less common in kids d/t elasticity in bones, usually requires severe trauma
• adults d/t violent impacts
• stable: non-displaced
• unstable: often require fixation (characterized by complete separation of symphysis pubis and opening in pelvic ring)

Question 43

Femoral Fractures

Answer 43

• intracapsular and trochanteric 2 most common
• 80% in 60+ more often in women
• 20% die within 1 year status post
• common MOI: osteoporosis –> fracture –> pt falls