Biomechanics WK2- DPT

types of joint surfaces

ovoid, planar, sellar

ovoid

most joints, convex and concave members

saddle

reciprocal surfaces, convex and concave members will switch depending on plane view

arthrokinematic movements

roll, glide, spin

roll movement

different points on the surface are in contact with different points on a second surface

glide movement

one point is in contact with different points on a second surface

rule for convex bone moving on concave

roll and glide occur in opposite direction

• bone end rolls in direction bone moves

• bone end glides in opposite direction

• (shoulder abducting)

rule for concave bone moving on convex

roll and glide occur in same direction

• bone end rolls in direction bone moves

• bone end glides in same direction

osteokinematic and arthrokinematic movements

classical and accessory

classical movement is split into…

active ROM and passive ROM

accessory movement is split into…

component and joint play

component movements can be split into

adjunct rotation and conjunct rotation

adjunct rotation

can control

occurs because of muscle force

conjunct rotation

cannot be controlled

occurs because of joint geometry

joint play movements

occur in response to external force

• medial/lateral glide

• anterior/posterior glide

• distraction/compression

• * some joint play is healthy to absorb shock

movements in the planar joint surface

osteo= translatory

arthro= glide

movements in the ovoid joint surface

osteo= swing osteo= spin

arthro= roll & glide arthro= spin

movements in the sellar joint surface

osteo= swing

arthro= roll & glide

2 joint positions

close packed position (CPP) and loose packed position (LPP)

close packed position

max congruency between articular surfaces

greatest tension in capsule & ligaments

creates compression of joint

loose packed position

rest position, greatest amount of wiggle in joint

positioning of the hip joint in LPP and CPP

LPP: 30° flex, 30° abd, slight lat rotation

CPP: ext, med rotation, abd

positioning of the knee joint in LPP and CPP

LPP: 25° flex

CPP: full ext and lat rotation of tibia

problems with manual muscle testing (MMT)

spasticity and return to sport

key points for positioning a patient for MMT

• free full ROM

• against gravity/ movement away from the floor

• minimize chance for muscle substitution

where and when to apply resistance during MMT

• perpendicular pressure at the distal end of the moving segment

• after seeing full ROM

types of resistance tests

• break test

• make test

• strength through range

break test

PT applies max force to move body part out of end range

make test (active resistance test)

PT slowly builds resistance to match patient’s force

strength through range

PT applies force but allows motion through full ROM

fair (3/5)

move through full ROM against gravity

good (4/5)

move through full ROM and somewhat less than max resistance

normal (5/5)

full ROM and full max resistance

poor (2/5)

full ROM in gravity lessened position

trace (1/5)

palpable muscle contraction, no visible movement

zero (0/5)

no movement or contraction

3+ / 5

can take little resistance at end ROM against gravity

3- / 5

more than ½ but not full ROM against gravity

2+ / 5

less than ½ but some ROM against gravity OR can take little resistance at end ROM in gravity lessened position

2- / 5

more than ½ but not full ROM in gravity lessened position

1+ / 5

less than ½ but some ROM in gravity lessened position

factors of MMT

• tester strength

• patient understanding/cooperation

• patient age

• pain

• limits in ROM

• fatigue

• muscle substitution

• upper motor neuron dysfunction

how to improve reliability in MMT

• proper positioning

• adequate stabilization

• non-painful contact

• consistent pressure and position

• avoid bias and change in patient instructions

acetabular labrum

cartilage ring around acetabulum, embraces femoral head

hip joint capsule

• strong and dense

• 2 types of fibers

  • longitudinal and zona orbicularis

• nearly complete socket for femoral head

• blood vessels supply head and neck

what lines non-articular surfaces

synovial membrane

ligaments of hip joint

• iliofemoral

• ischiofemoral

• pubofemoral

iliofemoral ligament

• Y ligament of Bigelow

• triangle shape

• 2 dense bands

pubofemoral ligament

from pubis to base of neck

ischiofemoral ligament

• posterior and inferior acetabulum to inner greater trochanter

• spiral course

• weakest

ligament function - abduction

pubofemoral taut

ligament function - adduction

lateral band of iliofemoral taut

ligament function - ER

iliofemoral and pubofemoral taut

ligament function - IR

ischiofemoral taut

ligament function - relaxed stance

hyperextended hip, iliofemoral ligament taut

trochanteric or gluteal bursitis

• pain posterior and superior to greater trochanter

• most common in hip region

ischial bursitis

• pain over ischial tuberosity

• common in individuals that sit for prolonged periods of time

iliopectineal bursitis

• causes anterior hip pain

• snapping hip syndrome

factors affecting muscle function

• weight bearing and non-weight bearing

• posture (bilateral or unilateral) (better balance side to side than front to back)

• size of muscle

• starting point of lower extremity

• fixation (2 joint muscles)

  • look at distal joint because it affect proximal joint

stability key points of hip joint

• relatively free mobile and stable

• less mobile than shoulder but more stable

• accommodate function

  • support body weight

  • allow for locomotion

factors improving stability

• gravity

• acetabulum, labrum, zona orbicularis fibers enclose femoral head

• atmospheric pressure

• balance between anatomic factors

  • strong ligaments and muscle pull approximates joint

• bony configuration

internal rotation limited by…

• posterior capsule

• ischiofemoral ligament

• tight external rotators

primary hip abductors

gluteus medius and gluteus minimus

secondary hip abductors

TFL and gluteus maximus

what muscle is the best hip abductor

gluteus medius

internal rotation is limited by…

• posterior capsule

• ischiofemoral ligament

• tight external rotators

pes anserine is the insertion of tendons…

• sartorius

• gracilis

• semitendinosus

primary hip flexors

• iliopsoas

• TFL

• rectus femoris

• sartorius

secondary hip flexors

• pectineus

• adductor longus

• gluteus minimus

main hip flexor

iliopsoas

hip flexion limited by

• soft tissue

• femoral neck on acetabular labrum

• tight hamstrings

• vertebral limitations

primary hip adductors

• adductor longus

• adductor brevis

• adductor magnus

• gracilis

secondary hip adductors

• pectineus

• hamstrings

• obturator internus and externus

• quadratus femoris

hip adduction limited by…

• superior capsule

• iliotrochanteric ligament

• abductor tightness

complexes of knee

• tibio-femoral joint

• patello-femoral joint

tibio-femoral joint

femoral condyles and tibial plateaus

what separates patellofemoral and tibiofemoral joints

medial and lateral grooves

femoral condyles

• biconvex

• each condyle convex both medial-lateral and anterior-posterior

• axes of condyles diverge posteriorly

• lateral facet is more prominent

lateral tibial tubercle

• “Gerdy’s tubercle”

• attachment of IT band

the tibial plateaus are… when menisci are attached

both concave in both planes

nerve that passes over fibular neck

common fibular nerve (peroneal nerve)

knee ligaments are responsible for …

keeping the knee stable

excessive genu valgum

• “knock kneed”

• angle of femur and tibia less than or equal to 165°

genu varum

• “bow-legged”

• angle of femur and tibia greater than or equal to 180°

hyperextension of the knee

• considered to be extension from 0-10°

  • greater than 10° termed genu recurvatum

menisci

• semi-lunar cartilage, moon shaped fibrocartilage structure

• flat interior surface attaches to tibial plateaus

medial meniscus characteristics

posterior horn broader than anterior

• semi-circular

lateral meniscus characteristics

more circular

posterior and anterior horns equal

menisci horns connect directly to

tibia

meniscus and coronary ligaments blend with

knee capsule

what separates lateral collateral ligament form meniscus

popliteus

You are testing your patient’s right shoulder abduction strength. Your patient is standing in front of you.  You ask your patient to abduct his arm over his head.  He is unable to move through full range but is able to move through about 75% of the motion.  He has full passive motion, but actively he can only raise his arm about 75% of the motion.  What is the manual muscle test grade of his right shoulder abductors:

3-

You then test the right shoulder abduction strength of another patient.  This patient is unable to raise her arm against gravity.  You then have the patient lie down supine.  You support the weight of her arm and again ask her to abduct her arm overhead.  She is able to move the arm through about 25% of the motion.  She has full passive motion, but actively she can only move her arm through 25% of the motion.  What is the manual muscle test grade of her right shoulder abductors:

1+

Thinking arthrokinematically, there are 3 basic types of joint surfaces.  Which of the following types is the MOST COMMON joint surface:

ovoid

The joint surface influences the type of arthrokinematic motions that can occur at that joint.  What type of joint surface do the femoral head and the pelvic acetabulum possess:

ovoid

In the hip joint, which joint surface is the CONVEX member:

femoral head

Osteokinematically, hip abduction and adduction are classified as rotary motions or more specifically swings.  What type of arthrokinematic motions occur during hip abduction and adduction:

roll and glide

The concave-convex rule dictates the pattern of rolling and gliding that occurs at a joint.  Which of the following statements best describes the arthrokinematics that occur with open chain shoulder abduction, the convex humeral head moving on the concave glenoid fossa:

humeral head rolls superiorly and glides inferiorly

Which of the following statements best describes the arthrokinematics that occur with open chain knee extension, the concave tibial plateaus moving on the convex femoral condyles:

tibia rolls and glides anterior

At the end of open chain knee extension, the tibia laterally rotates to put the knee into the "screw home" position.  The lateral rotation is a motion that accompanies knee extension.  It occurs because of the geometry of the knee joint and cannot be controlled voluntarily.  This type of motion is known as a:

conjunct rotation