Intro to basic joint Biomechanics

osteokinematics

gross movement of bones

physiologic motion

motions take place in one of 3 planes

arthrokinematics

movement occurring at the joint

produced by external force

accessory or joint play motions(non-phyiologic) doesn’t equal conjunct rotation

slide/glide, spin, roll

convex - concave rule

what determines a joint’s function

its structure

synarthrosis

ex: fibrous and cartilaginous joints

minimal to no movement

reinforced by a combination of fibrous and cartilaginous connective tissues

pubic symphysis(cartilaginous), cranial sutures(fibrous)

Diarthrosis

aka synovial joint

fluid-filled joint cavity = moderate to extensive movement

degrees of freedom associated with each joint

7 types

synovial joint characteristics

articular cartilage, synovial membrane, synovial fluid, joint capsule, ligaments, blood vessels, nerves

which surface is AOR on

convex and it moves(I-AOR)

benefits of I-AOR

efficiency with movement/motion

improved congruency of the joint

produces a more fluid movement

Open-packed/loose-packed position

point of maximum in-congruency

capsule is loose

test joint mobility here

close-packed/closed-pack position

maximum congruency

joint capsule and ligaments are taut(can’t pull them apart)(feels tight)

extended elbow

open chain motion

distal end is free to move

kicking

closed chain motion

distal end is fixed

squat

joint congruence

how well two structures fit each other