By- Dr. Armaan SinghBy- Dr. Armaan Singh

Classification & Detail Info. Classification & Detail Info. {PPT.}{PPT.} of of Bones and JointsBones and Joints

Bone

CORTICAL BONE

• Dense, hard bone found in cortex

• Three quarters of skeletal tissue

• High mineral content

Carter & Hayes, 1976

• Stiffer than cancellous

• Withstands greater stress, less strain

• Fractures when strain exceeds

2% Carter & Hayes, 1976

Cortical Bone

• Low surface area

• Porosity 5-30%

• Slow metabolic rate

• Develops in line of stress

Einhorn,1996

Cortical Bone

TIBIA

• The shaft of the tibia is mainly compact bone

• A central medullary cavity containing mainly fat

• The ends are compact bone

• With an inner core of cancellous bone

• The periosteum is the vascular fibrous connective tissue investing bone

TRABECULAR OR CANCELLOUS BONE

• Found inside cortical shell e.g. Vertebrae

• Consists of horizontal and vertical plates

• Spaces are filled with bone marrow

• Large surface area

• Porosity is between 30-90%

• Greater capacity to store energy

• In vitro fractures at strains >75%

• Metabolically more active

• More sensitive to changes in endocrine hormones

Carter & Hayes,1976; Einhorn, 1996

Trabecular or Cancellous Bone

• Compressive strength is proportional to the square of the apparent density

• Small changes in density

• Large change in strength

Dalen et al., 1976

Cancellous Bone

• Organic matrix

• Type I collagen forms 90% of skeletal weight

• Mineral hydroxyapatite ratio

• Calcium 10

• Phosphate 6

• Carbonate 1

Bone

BONE REMODELLING

• Bone is a living tissue

• Osteoclastic activity i.e. bone resorption takes only few days

• Osteoblastic or bone formation takes several months

Bone Remodelling

Quiescence

Activation

Resorption

Formation

Quiescence

Normal bone turnover

Osteoporotic bone turnover

osteocytes

bone

osteoblastosteoidnew bone

osteoclast

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Phases of Bone Remodelling

A HEALTHY SKELETON DEPENDS ON A BALANCED RANK LIGAND:

OPG RATIO

Prevents Bone Loss

RANK Ligand

OPG

Increases Bone Loss

RANK

Ligand

OPG

RANK Ligand

OPG

A HEALTHY SKELETON REQUIRES A BALANCE OF BONE RESORPTION AND FORMATION

Resting Reversal

Activation

Adapted from Baron, R. General Principles of Bone Biology. In: Primer on the Metabolic Bone Diseases and Disorders of Mineral Metabolism. Favus MJ (Ed.) 5th Edition. American Society for Bone and Mineral Research, Washington DC, 2003: 1–8

When bone turnover is increased, bone loss

dominates

Formation: 3 months

Resorption: 10 days

REGULATION OF OSTEOCLASTOGENESIS

Osteoclast precursor

osteoblast

Osteoclast

RANKL

OPG

RANK

c-fms

M-CSF

differentiation

Monoclonal antibody to RANKLAMG 162

Bones Require

• Normal hormones

• Adequate calories

• Particular protein

• Calcium

• Vitamin D

• Regular weight bearing

• Exercise

Bone

• The rate of turnover is determined by hormonal and local factors

Bone

Four Mechanisms of Bone Mass Regulation

• Changes in bone function lead to changes in bone

• Bone is laid down where needed

• Bone is resorbed where it is not needed

Wolff, 1892

Wolff’s Law

• Osteogenesis is induced by dynamic not static strains

• The optimal type of osteogenic activity should provide relatively high levels of strain

Rubin & Lanyon, 1984

Mechanical Strain

• Tensile forces result in osteoclastic activity

• On the convex side of an angulated bone

• Compressive force results in osteoblastic activity on concave side

Bone

Bones require

• Normal hormones

• Adequate calories

• Particularly protein

• Calcium

• Vitamin D

• Regular weight bearing exercise

Bone

Age (years)

Attainment of Peak Bone Mass

Consolidation Age Related Bone Loss

Men

Women

Menopause

0 10 20 30 40 50 60

Fracturethreshold

1. Compston JE. Clinical Endocrinology 1990;33:653-682

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Age Related Changes in Bone Mass1

PEAK BONE MASS• Genetic

• Environmental factors

• Mechanical strain

• Hormones

PEAK BONE MASS• Weight bearing activity during

adolescence and early adulthood was a far more important predictor of peak bone mass than calcium intake

Welten et al., 1994

LOW PEAK BONE MASS• Growing bone has a greater capacity to

add new bone to skeleton than mature bone

Forwood & Burr, 1993

OSTEOGENESIS• Muscle action is main stimulus for

bone formation

• Mechanical force

• Weight bearing

Birge et al., 1968

CLASSIFICATION OF BONESBy Shape

• Long

• Short

• Flat

• Irregular

• Sesamoid

SHORT BONES

Short bones

• Found only in the hand and foot

• Vary in shape

FLAT BONES AND IRREGULAR BONESFlat bones

• Usually consist of two layers

of compact bone

• Cancellous bone lies in

between

• Found in the skull and

sternum

Irregular bones

• Occur in the face and

vertebrae

SESAMOID BONESSesamoid bones

• Develop in tendons where

they cross bone

• Or articular surfaces,

patella

• Sesamoids in relation to

thumb and hallux

LONG BONESLong bones

• Have a cartilaginous

ossification

• Are found mainly in the limbs

and consist of:

• Shaft (the diaphysis), which is ossified from the primary center of ossification during intrauterine life

• The cavity of the shaft, contains red marrow in the fetus, yellow fat in the adult

BONE GROWTH• Diaphysis: shaft ossified from primary

center of ossification which appears 6-8th week of intrauterine life

• Epiphysis: ossified from secondary center

• Growth plate is cartilage

• Injury of epiphysis affects growth

EPIPHYSIS• Is ossified from a secondary center of

ossification

• These usually appear shortly after birth

• Except for the lower end of the femur, which appears 9 months intrauterine life, just before birth

• Epiphysis unite with the diaphysis (shaft) from puberty to early twenties depending on the bone involved

METAPHYSIS• The portion of the diaphysis beside the

epiphysis is called the metaphysis

• This is the region where osteomyelitis tends to occur in young people

• The metaphyseal arteries are end arteries until ossification is completed i.e. the epiphyseal plate is ossified

BONES

• Long bones grow in length from epiphyseal plates

• Increase in width is from periosteum

• Damage to the epiphyseal growth plate can lead to premature closing and retards normal growth

• Anabolic steroids will also cause early closure

EPIPHYSES

• Traction epiphyses

• The tibial tuberosity

• Osgood-Schlatters

• Medial epicondyle of the humerus, in ‘little league elbow’

• Compression epiphysis

• The distal end of the humerus

MUSCULOSKELETAL PROBLEMS

• Younger athletes

• Suffer many of the same injuries and illnesses as adults

• Differences is the structure of growing bone

Avulsed epiphysis

LESIONS WHICH AFFECT GROWTH PLATEArticular

• Perthes: femoral

• Kienbock: lunate

• Kohler: navicular

• Freiberg: 2nd metatarsal

• Osteochondritis dissecans

• Lateral aspect medial femoral condyle

EPIPHYSEAL INJURIES

• Shearing forces

• Avulsion forces

• Compression fractures

• Metaphyseal

• Growth plate

• Avulsion

GROWTH PLATE FRACTURESSALTER-HARRIS CLASSIFICATION

• Type 1 and type 2 heal well

• Type 3 and type 4 involve joint surface as well as growth plate

• Type 5 compression of growth plate

• Difficult to detect

• Growth ceases

BLOOD SUPPLY OF BONE

• Periosteal arteries enter bone at several points to supply the compact bone

• Nutrient arteries supply spongy bone and bone marrow

BLOOD SUPPLY OF BONE

• Periosteal arteries enter the bone at several points to supply the compact bone

• Nutrient arteries supply the spongy bone and bone marrow

• Epiphyseal arteries supply the epiphysis

• Metaphyseal arteries supply the metaphysis

BLOOD SUPPLY OF BONE• Periosteal arteries occur particularly at the sites of

attachments of muscles and tendons

• If a group of muscles inserted into a bone is paralysed before puberty

• That bone will be shorter than the equivalent bone on the other side

• Due to reduced blood supply from the muscles involved

• The lack of stimulus to bone from lack of muscle contractions

• After puberty only muscle bulk is reduced

• Epiphyseal arteries supply the epiphysis

• Metaphyseal arteries supply the metaphysis

• These are end arteries until epiphysis unites with diaphysis

Blood Supply of Bone

AVASCULAR NECROSIS• Bones that have a large surface area covered

with articular cartilage tend to have a poorer blood supply

• Avascular necrosis occurs if blood supply is cut off due to fracture

• e.g. head of femur, due to fracture of neck of femur

• Proximal portion of the scaphoid

• Body of talus or dislocation e.g. lunate

APOPHYSIS• Tendon attachment to growth plate

• Traction injuries may occur

• Medial epicondylitis

• Limit numbers of pitches in baseball

• Osgood-Schlatters lesion of tibial tuberosity

• 12-16 year olds

AVULSION FRACTURES

Medial epicondyle

BONES IN CHILDREN

• More flexible

• More elastic

• Less brittle

• Growth plate is weakest link

• Periosteum thicker

• Articular cartilage thicker

• Junction between

• Metaphysis and epiphysis vulnerable

• Shearing forces

• Tendon attachment to apophysis weak

Bones in Children

EATING DISORDERSMay result in

• Delayed bone growth

• Delayed menarche

• Low peak bone mass

• Osteopenia or osteoporosis

• Increased musculo-skeletal problems

ARTICULAR CARTILAGE• The thickness of the cartilage

depends on the stress to which it is normally subjected

• Varies over the joint surface

• Patella has the thickest articular cartilage

• Articular cartilage is avascular

• Nourished by synovial fluid, from capillaries in the synovial membrane

• When the articular surfaces are in contact

Hollingshead, 1969

Articular Cartilage

MUSCULOSKELETAL INJURIES

Extrinsic factors

• Sport

• Contact sports

• Environment

• Equipment

• Protective

• Overuse

Intrinsic factors

• Physical

• Physiological

• Psychological

• Previous injury

BONE PAIN• Osteomyelitis

• Tumour (night pain)

• Osteochondritis

• Rheumatoid arthritis

STRESS FRACTURESSTRESS FRACTURES• Biomechanical causes

• Training errors

• Athletic triad

• Amenorrhea

• Eating disorders

• Osteoporosisor osteopenia

• X-ray many times negative

• MRI is extremely sensitive

• Stress fracture of the femoral neck is potentially serious and need often surgery

JOINT

• Junction between two bones

• Function and movement depends

• Size and shape of articular surfaces

• Soft tissues surrounding the joint

RANGE OF JOINT MOVEMENT• Shape of articulating surfaces

• Restraint due to ligaments and muscles crossing joint

• Pain, weakness, spasm or contracture of muscles

• Bulk of adjacent soft tissue

• Impingement of bony surfaces

• Scarring of skin due to injury or burns

MUSCLES• Muscle can only act on a joint, if it crosses

the joint

• Muscles that have a common action on the joint tend to have same nerve supply

• Usually nerve of compartment gives an articular branch to joint

• Exception, flexors of the elbow, where median, ulnar and radial all give branches

CLASSIFICATION OF JOINTS• Fibrous

• Cartilaginous

• Primary and secondary

• Synovial

FIBROUS JOINTS

• Fibrous union

• Slight movement

• Gomphosis i.e. tooth and its socket

• Sutures

• Syndesmosis

FIBROUS (SUTURE)• Consists of dense fibrous connective

tissue between the bones

• Periosteum covering the opposing surfaces of the bones

• Synostosis

• Fusion of the bones across the sutural joints continues throughout life

FIBROUS SYNDESMOSIS

• Interosseous membranes: radius and ulna, similar in lower limb and inferior tibio-fibular joint

PRIMARY CARTILAGINOUS• Cartilage continuous with bone

• No movement

• Rib and costal cartilage: costo-chondral joints

• First costal cartilage and sternum

• Diaphysis and epiphysis

• Epiphysis and diaphysis

• Rib and costal cartilage

• 1st costal cartilage and manubrium sternum

• No movement

Primary Cartilaginous

• Epiphysis and diaphysis

Primary Cartilaginous

SECONDARY CARTILAGINOUS• Hyaline cartilage

• Disc of fibro-cartilage

• Mid line joints

• Very little movement

• Intervertebral discs

• Manubrium and body of sternum

• Pubic symphysis

Secondary Cartilaginous

SYNOVIAL• Hyaline articular cartilage

• Capsule

• Synovial membrane lines capsule, non articular structures inside joint

• Never lines articular cartilage

• Discs or menisci are fibro cartilage

TYPES OF SYNOVIAL JOINTS

• Shape of articular surface

• Plane

• Hinge

• Condylar

• Pivot

• Saddle

• Ellipsoid

• Ball and socket

TYPES OF SYNOVIAL JOINTSSHAPE OF ARTICULAR SURFACE

• Plane: talo-calcaneal

• Hinge: elbow, interphalangeal joints

• Condylar: knee, metacarpophalangeal

• Pivot: superior radio-ulnar, atlanto-axial

• Saddle: trapezium-base first metacarpal

• Ellipsoid: wrist

• Ball and socket: hip, shoulder, talo-calcaneo-navicular

DESCRIPTION OF A JOINTClassify

• Shape of articular surfaces

• Cartilage covering surface

• Attachments of capsule

• Ligaments, disc

• Haversian pads of fats fill joint spaces

• Synovial membrane

• Movements

• Relations

• Blood and nerve supply

• Clinical significance

CAPSULE• Collagen

• Expanded tendon

• Sesamoid bone

• Thickened to form ligaments

• Haversian pads of fats fill joint spaces

PLANE JOINT

• Surface is flat

• Only allows gliding movement

• Non-axial e.g. facet joints of vertebrae

• Talo-calcaneal joint

Talo-calcaneal

HINGE JOINT

• Movement in one plane (uniaxial) e.g. elbow

• Interphalangeal joints in hand and foot

• Strong ligaments on sides, weaker anterior and posterior

PIVOT JOINT

• Allows rotation around a single axis

• Uni axial

• Atlanto axial

• Superior and inferior radioulnar joints

SADDLE JOINT

• Saddle-shaped concavo-convex surfaces

• Movement in two planes (biaxial) e.g. carpo-metacarpal of the thumb (trapezium and base of first metacarpal)

CONDYLARJOINT

• Two axes at right angles to each other

• Movement in two planes (biaxial)

• Meta-carpophalangeal

• Sternoclavicular

• Atlanto-occipital joints

BALL AND SOCKET JOINT• Allows movement in three axes

• Multiaxial

• Hip

• Shoulder

• Talocalcaneo-navicular joints

SYNOVIAL JOINTS• Discs of fibro cartilage or menisci in some joints

• Blood supply at periphery

• Increase the depth and mobility of the joint

• Synovial folds in joints

• Synovial membrane

• Nerve endings also in fat

• Infrapatellar fat pad

• Facet joints of lumbar vertebrae

• Elbow

CAPSULE• Consists of collagen (type I)

• Thickened to form ligaments

• Expanded quadriceps tendon

• Sesamoid bone in quadriceps tendon

• Synovial membrane lines the inner surface of the capsule and non articular structures inside capsule

FIBROCARTILAGENOUS DISCS

Infrapatellar fat pad

Lateralmeniscus

HAVERSIAN PADS OF FAT• Fat pads are semi-liquid at body

temperature

• They fill the changing spaces that occur during movement

• These pads help to reduce friction between moving tissues

SENSORY SUPPLY• Sensory nerves in fibrous capsule and

ligaments and synovial membrane

• Information about pain

• The position of the joint (proprioception)

• Poor proprioception predisposes to injury

Isakov & Mizrahi, 1997

SYNOVIAL JOINT

• The epiphyses of many long bones are intracapsular

• Injury to a joint, before the cessation of growth, may damage the epiphyseal cartilage

• The articular surfaces are covered by hyaline or articular cartilage

HYALINE CARTILAGE• Hyaline cartilage is avascular

• Nutrition is by diffusion from the synovial fluid

• Must be in contact with the opposing articular surface

OPEN AND CLOSED KINETIC CHAIN

• Open kinetic chain

• The distal segment is free in space

• Raising the hand in the air

• Closed kinetic chain

• The distal segment is fixed

THE DEGREES OF FREEDOM

• Joints can also be classified by degrees of freedom

• Reflects the axis of movement

• If a joint has only one axis

• It has only one degree of freedom

• Nonaxial: no axis of rotation

• Uniaxial: move in one axis

• Have one degree of freedom

• Acromioclavicular 1

• Elbow 1, radioulnar 1

• Proximal and distal interphalangeal 1

• Biaxial: move in two axes

• Have two degrees of freedom

• Metacarpophalangeal 2 +

• Wrist 2 +

• Multiaxial: move in three axes

• Have three degrees of freedom

• Maximum any joint can possess

• Shoulder 3

• Sternoclavicular 3

• Hip 3

• Talocalcaneonavicular 3

The Degrees of Freedom

CLOSE-PACKED

• Stable position

• Surfaces fit together

• Ligaments taut

• Spiral twist

• Screw home articular surface

• Stable position

LEAST-PACKED

• Joint more likely to be injured in least-packed position

• Capsule slackest

• Joint held in this

• Position when injured

• Fluid in knee held in 20° flexion

• Shape of articulating surfaces

• Restraint due to ligaments and muscles crossing joint

• Pain, weakness, spasm or contracture of muscles

• Bulk of adjacent soft tissue

• Impingement of bony surfaces

• Scarring of skin due to injury or burns

RANGE OF JOINT MOVEMENT