Joint structures and function

In detail description of bones, joints, types of bones and joints, and joint function along with biomechanical laws related to joint functions

1. Joint Structure and
Function
RADHIKA CHINTAMANI
ASST. PROFESSOR
OMT

2. Joint: definition, structures in and around the joint
Basic Principles: 1, 2, 3, 4, 5.
Wolf’s Law: explanation
Structure of Connective tissue: Cellular and
Extracellular {interfibrillar and fibrillar}
Cellular: Connective tissue cell type
Extracellular matrix:
a.Fibrillar component: collagen and elastin.
b.Interfibrillar component: water, proteins:
glycosaminoglycans and proteoglycans(PG’s)
CONTENTS

3. It is an articulation connecting two or more components
of a structure. - Cynthia Norkin.
Joint structure consists of: bony articular parts, meniscii,
cartilage, synovial fluid, capsule, ligaments, tendons, fat
pads, bursae, nerves and blood vessels.
Structures in and around are classified into two types:
intra-articular strutures and extra-articular structures.
Joint

4. Intra-articular Structures Extra-articular Structures
Articular surfaces Tendons
Meniscii Bursae
Cartilage Ligaments
Synovial lining along with synovial fluidMuscles
Capsule

5. 1.The design of a joint and the materials used in its
construction depend partly on the function of the
joint and partly on the nature of components.
2.Joints providing stability have different design than
those providing mobility.
3.The compelxity of design and composition matches
the range of functional demands- i.e. the more varied
the demand the more complex the joint.
4.Human joints serve many functions, hence are more
complex than most-man made joints.
5.Wolff’s law
Basic Principles

6. By Julius Wolff
Year: 19
th
century
Definition: Changes occur in joint structures in order to
allow them to meet functional demands. – Cynthia
Norkin.
Mechanism: if loading on a particular bone increases it
tends to remodel itself over time hence resisting that
amount of load in future.
The law doesn’t only pertain to bone but, as well as to
tendon and ligaments.
Wolff’s Law

7. Connective tissue
Cellular matrix
Extra cellular matrix
Contents

8. It is a type of tissue that supports, binds, connects or
separates other tissue from each other, embedded with
few cells in a matrix.
Connective tissue is further made up of cellular (fixed
and transient) & extracellular (interfibrillar and
fibrillar)
Connective tissue

10. Cellular Matrix: a. Fixed type
NAME LOCATION FUNCTION
Fibroblast Found in tendon, ligament, skin,
bone. etc
Creates mostly type I
collagen
Chondrobalst These are differentiated
fibrobalsts found in cartilage
Type II collagen
Osteoblast bone Type I collagen and
production of
hydroxyapetite
Osteocalst bone Bone resorption
Mast cells Various connective tissue Inflammatory cells
Adipose cells Adipose tissue Produce and store fat
Mesenchyme
cells
Embryos and bone marrow Differentiate into
connective tissue

11. Cellular Matrix: b. Transient type
NAME FUNCTION
Lymphocytes Have surface protein specific for antigen
Neutrophils Involved in fighting infection
Macrophages Involved in immune response
Plasma cells Produce antibodies

12. The interfibrillar component of connective tissue is
composed of hydrated networks of proteins: primarily
glycoproteins and proteoglycans (PGs)
PG: the PGs are found mainly in connective tissues,
where they contribute to the organization and physical
properties of the ECM.
GAG’s: The GAGs are all very similar to glucose in
structure and are distinguished by the number and location
of the amine and sulfate groups that are attached. The
major types of sulfated GAGs include chondroitin 4 and
chondroitin 6 sulfate, keratan sulfate, heparin,
heparan sulfate, and dermatan sulfate.
Extracellular Matrix: a. Interfibrillar

13. Glycoproteins such as fibronectin, laminin,
chondronectin, osteonectin, tenascin, and entactin
play an important role in fastening the various
components of the ECM together and in the adhesion
between collagen and integrin molecules in the cell
membranes of the resident cells of the tissue.

14. The fibrillar, or fibrous, component of the ECM
contains two major classes of structural proteins:
collagen and elastin.2
Collagen: has a tensile strength and is responsible for
the functional integrity of connective tissue structures
and their resistance to tensile forces.
Elastin: Each elastin molecule uncoils into a more
extended conformation when the fiber is stretched and
will recoil spontaneously as soon as the stretching force
is relaxed.
b. Fibrillar

15. Bone contains two principle structural components:
collagen (Type I) and hydroxyapatite (HA).
Organic components of bone make up approximately
40% of the bone’s dry weight, and collagen is
responsible for about 90% of bone’s organic content.
The inorganic, or mineral, components make up
approximately 60% of the bone’s dry weight.
The primary mineral component is HA, which is a
calcium phosphate–based mineral: Ca10(PO4)6(OH)2.
The HA crystals are found primarily between the
collagen fibers
Bone

16. types II, IX, and X are known as cartilage-specific
collagens because they seem to be found only in
cartilage.
Because HA is a ceramic, bone can be expected to have
ceramic-like properties. For example, ceramics are
generally brittle, tolerating little deformation before
fracture.
Ceramics and bone are also relatively strong in
compression but weak in tension.
The structure of human bone changes with age.
REMEMBER

17. Immature bone: weaker, flexible and seen in children.
Mature Bone: stronger, more rigid and seen in adults.
Cancellous Bone: spongy or trabecular, not dense as
cortical.
Cortical Bone: compact bone, is hard and dense.
BONE TYPES

18. Wolff observed that bone, especially cancellous bone,
is oriented to resist the primary forces to which bone is
subjected.
Wolff suggested that “the shape of bone is determined
only by static loading”
Note

19. Flat: Ribs, occiput, frontal
Long: humerus, femur, tibia, fibula
Short: tarsals, carpals
Irregular: vertebrae, pubis, ilium, ischium
Sesamoid: patella
Classification of bones

20. Provides structural support
Protect the vital organs
Allows body to move through muscles, or perform any
other activity
Depending on kinematic chain it varies: stability and
mobility
Functions of bones

21. Bone is isotropic transversely and anisotropic
longitudinally.
Stress-strain curves for bone demonstrate that cortical
bone is stiffer than cancellous (trabecular) bone,
meaning that cortical bone can withstand greater stress
but less strain than the cancellous bone.
Cancellous bone can sustain strains of 75% before
failing in vivo, but cortical bone will fail if strain
exceeds 2%.
Bone can withstand greater stress, and will undergo
less strain, in compression than in tension.
Principle features of bone

22. The physiologic response of trabecular bone to an
increase in loading is hypertrophy. If loading is
decreased or absent, the trabeculae become smaller and
weaker.
Repeated loadings, either high repetition coupled with
low load or low repetition with high load, can cause
permanent strain and lead to bone failure. Bone loses
stiffness and strength with repetitive loading.
Bone loses stiffness and strength with repetitive
loading as a result of creep strain. Creep strain occurs
when a tissue is loaded repetitively during the time
the material is undergoing creep.

23. Synarthrosis:
a.Fibrous joints: sutures, ghomphoses, syndesmoses.
b.Cartilagenous joints: symphysis, synchondroses.
Diarthrosis:
Classification of joints

24. The material used to connect the bony components in
synarthrodial joints is interosseus connective tissue.
Divided into two types based on the type of connective
tissue used to connect the bones.
a.Fibrous: fibrous tissue directly unites the bone.
b.Cartilagenous: cartilage is used to connect the bones
forming joint; either fibrocartilagenous or hyaline
cartilage.
Synarthrosis

25. 1. Sutures: two bony components are united by
collagenous sutural ligament or membrane.
The ends of the bony components are shaped so that
the edges interlock or overlap one another.
Eg: skull bones
Fibrous

26. 2.Gomphosis joint: surfaces of bony components are
adapted to each other like a peg in hole.
Component parts are connected by fibrous tissue.
Eg: tooth, mandible or maxilla.
3.Syndesmosis: Two bony components are directly
connected by interosseous membrane.
Eg: radio-ulnar joint and tibio-femoral joints.

27. Symphysis: two bony components are covered with a
thin lamina of hyaline cartilage and directly joined by
fibrocartilage in the form of disks or pads
EG: Intervertebral joints, pubic symphysis
Synchondrosis: material used for connecting the two
components is hyaline cartilage. The cartilage forms a
bond between two ossifying centers of bone. The
function of this type of joint is to permit bone growth
while also providing stability and allowing a small
amount of mobility.
Eg: first costosternal joint.
Cartillagenous

28. The system of joints and links is constructed so that motion of
one link at one joint will produce motion at all of the other
joints in the system in a predictable manner. The kinematic
chain can be open or closed.
In an open kinematic chain, one joint can move
independently of others in the chain.
When one end of the chain remains fixed, it creates a closed
system or closed kinematic chain.
Under these conditions, movement at one joint automatically
creates movement in other joints in the chain.
KINEMTICS

29. Range of motion: the range or the arc through which the
movement of one bony lever occurs with respect to another.
There are two types of ROM’s:
a.Anatomical ROM: Movement of the joint within
anatomical limits.
b.Physiological ROM: movement of the joint beyond the
anatomical limit.
Joint motion

30. The extent of the anatomic range is determined by a number
of factors, including the shape of the joint surfaces, the joint
capsule, ligaments, muscle bulk, and surrounding
musculotendinous and bony structures.
Eg:
i.The humeroulnar joint at the elbow is limited in extension
by bony contact of the ulna on the olecranon fossa of the
humerus.
ii.The tibifemoral joint at the knee is limited in flexion by soft
tissue approximation at the popliteal fossa.

31. Given by cyriax
Experience felt by the therapist during the motion carried out
passively at the end of the range of passive physiologic ROM.
End feel

32. Hypermobility
Hypomobility
Ankylosed
Pathological ROM

33. Osteokinematics refers to the movement of the bones
in space during physiologic joint motion.
 These are the movements in the sagittal, frontal, and
transverse planes that occur at joints.
The movements are typically described by the plane
in which they occur, the axis about which they occur,
and the direction of movement.
Eg: Osteokinematic movements at the ulnohumeral
joint include flexion or extension (direction) of the
ulna on the humerus (or humerus on the ulna) in the
sagittal plane about a frontal axis.
Osteokinematics

34. Physiologic joint motion involves motion of bony
segments (osteokinematics) as well as motion of the
joint surfaces in relation to another.
Accompany voluntary movements, but can’t be
produced voluntarily.
The term arthrokinematics is used to refer to these
movements of joint surfaces on one another.
Arthrokinematics

35. 3 movements clustering
arthrokinematics of joint
The arthrokinematic motion
of the moving
segment is described in
relation to the nonmoving
segment.

36. Roll:
Rolling of one joint surface on another, as in a tire rolling on
the road.
The direction of rolling is described by the direction of
movement of the bone; thus, the femur rolls forward during
knee extension in standing.
During a pure rolling motion, a progression of points of contact
between the surfaces occurs.
Eg: In the knee, the femoral condyles roll on the fixed tibial
surface during knee flexion or extension in standing.

37. Slide:
Pure translatory motion.
Gliding of one component over another, as when a
braked wheel skids. The point of contact changes in the
fixed component as the sliding component moves over it.
Eg: In the hand, the proximal phalanx slides over the
fixed end of the metacarpal during flexion and extension.

38. Spin:
Spin is a pure rotatory motion. The same points remain
in contact on both the moving and stationary
components.
Eg: elbow, the head of the radius spins on the
capitulum of the humerus during supination and
pronation of the forearm.

39. Convex-concave rule: Convex joint surfaces roll
and glide in opposite directions, whereas concave
joint surfaces roll and slide in the same direction.
CONVEX: OPPOSITE
CONCAVE: SAME
CONCAVE-CONVEX RULE

40. OVOID SELLAR
One surface is convex and other
surface is concave
Each joint surface is both convex and
concave
DEPENDING ON THE SAHPE OF
ARTICULAR SURFACES

41. Joint motions commonly include a combination of
sliding, spinning, and rolling.
Although we typically describe the axis of rotation for
various joints in the body and use anatomical
landmarks to represent these axes, the combination of
sliding and spinning or rolling produces curvilinear
motion and a moving axis of motion.
The axis of rotation at any particular point in the
motion is called the instantaneous axis of rotation
(IAR).
NOTE

42. Combination motions, wherein a moving component
rolls in one direction and slides in the opposite
direction, help to increase the ROM available to the
joint and keep opposing joint surfaces in contact with
each other. Another method of increasing the range of
available motion is by permitting both components to
move at the same time.

43. All connective tissues will adapt to increased load
through changes in structural and/or material properties
(form follows function).
The load must be gradual and progressive; as the tissue
adapts to the new loading conditions, the load must
change to induce further adaptation.
The type of connective tissue formed will match the
type and volume of the load:
i.compression: cartilage or bone
ii.tension: ligament or tendon
Connective Tissue Response to
loads

44. Fracture
Subluxation
Dislocation
Avulsion fracture
Overuse injury
Pathological effects