MSK - Osteology (Complete)

The axial skeleton includes the

Skull, spine, and thorax

The appendicular skeleton includes the

Limbs, hands, feet, shoulder girdle, pelvis

Label the shoulder

bonus: which side is anterior?

1 - lesser tubercule

2 - acromion-clavicular joint

3 - clavicle

4 - glenoid cavity

5 - shaft of humerus

6 - head of humerus

7 - scapula

8 - coracoid process

9 - acromion process

bonus: the left side

Difference between male and female pelvis

What are accessory ossicles?

How do they form?

What can they be mistaken for?

Small extra bones near joints

Arise from unfused ossification centres

Can be mistaken for fractures and may become painful after trauma

3 types of accessory ossicles

Os trigonum

Accessory navicular

Fabella

Radiopaque and radiolucent meaning and examples

• Radiopaque means anything which appears WHITE on X-ray

• Radiolucent means anything which appears black or transparent

Bone, metal = radiopaque

tissue, fat and air = more radiolucent

What is each modality (CT, MRI, X-ray and ultrasound) best for:

• Assessing whether a tumor is benign or malignant

• Imaging muscle, tendon or ligaments

• Imaging soft tissue

• Imaging fractures

CT - to assess whether a tumor is benign or malignant

MRI - Muscle, tendon or ligaments

Ultrasound - Soft tissue

X-ray - Fracture

What are the 5 types of bone

Long

Short

Flat

Irregular

Sesamoid

Bone properties - explain what is meant by anisotropic

Bone strength varies with direction of force

strongest = the longitudinal axis

Intermediate strength = oblique angles

weakest = on the transverse axis

Bone properties - explain what is meant by viscoelasticity

Bones can deform under load and return to its original shape if force remains below the yield point

Forces beyond the yield point cause permanent damage/fracture

Bone properties - explain what is meant by Wolff’s Law

Bone adapts to the stresses placed upon it by altering its structure and mass

Increased loading = greater bone density

Decreased loading = lower bone density

Anatomy of the long bone

A - diaphysis

B - epiphysis

C - epiphyseal plate

D - metaphysis

E - medullary cavity

F - periosteum

G - articulated hyaline cartilage

Label the areas of the epiphyseal plate

What is the role of the epiphyseal plate?

Longitudinal bone growth in the immature skeleton

What is the role of each zone in the epiphyseal plate?

• Germination layer/resting zone - where chondrocytes (cartilage cells) are produced

• Proliferation zone - chondrocytes divide and form columns, driving bone length

• Hypertrophic zone - the weakest part of the plate, where chondrocytes lengthen, then enlarge and die

• Zone of provisional calcification — cartilage matrix calcifies, then osteoblasts move in and deposit bone

What are ossification centres and what can they be used for?

Meaning —> where bone ossification begins and spreads outward

Uses —> Identify bone growth deficiencies, identify the age of a child

State where each part of CRITOE is located (on which bone)

Capitulum

Radial head

Internal epicondyle

Trochlea

Olecranon

External epicondyle

Capitulum - distal humerus (lateral)

Radial head - proximal radius

Internal (medial) epicondyle - sticky out bit on the internal humerus

Trochlea - distal humerus (medial, right beside the capitulum)

Olecranon - proximal ulna (forms the point of the elbow)

External (lateral) epicondyle - sticky out bit on the lateral humerus

What is the Salter-Harris classification

Only used for paediatric

Grading scale to describe disruption of the epiphyseal growth plate from I-V (1-5). I is the least damaged with the best prognosis, V is the most damaged with the worst prognosis

Explain the Salter-Harris classification

S - Slipped - type I

A - Above (the growth plate) - type II

L - Lower (than the growth plate) = type III

TE - through everything = type IV

R - rammed = Type V

Use the Salter-Harris classification system to describe the fracture pattern

Type I - slipped

Use the Salter-Harris classification system to describe the fracture pattern

Type IV - though everything

Use the Salter-Harris classification system to describe the fracture pattern

Type III - lower than the growth plate

Use the Salter-Harris classification system to describe the fracture pattern

Type II - above the growth plate

Use the Salter-Harris classification system to describe the fracture pattern

Type V - growth plate rammed into the metaphysis

What is the Weber Classifaction?

Grading A-C used to describe ankle fractures based in the fibula’s level relative to the ankle joint

C is worse than A

What is the syndesmosis?

a fibrous joint where two bones, such as the tibia and fibula, are connected by strong ligaments and an interosseous membrane, allowing minimal movement

Explain Weber classification

A = Below the level of the syndesmosis (good prognosis)

B = at the level of the syndesmosis

C = above the level of the syndesmosis (makes the joint unstable, requires surgery)

Fractures of the proximal femur are either intracapsular or extracapsular. Describe what is meant by intracapsular fracture and the risk it poses

Intracapsular = involving femoral head and neck

Risk = can damage blood supply to femoral head, increasing the chance of

• avascular necrosis (cutting off the bones blood supply which can lead to death of the bone tissue)

• nonunion (bone fails to heal)

• malunion (bone heals in the wrong position)

Describe what is meant by extracapsular fracture and the risk it poses

Extracapsular - fractures below the femoral neck, or involving the trochanteric region

Risks

• high 1-year mortality (up to 50%)

• substantial bleeding

• risks related to immobility - deep vein thrombosis, chest infections, and pressure ulcers

Typical exam question: Using your knowledge of anatomy, pathology and pattern recognition can you explain the differences between the two X-ray images?

Image on the left shows intracapsualar hip fracture whereas the image on the right is normal.

Image on the left shows adequate exposure whereas image on the left is slightly underexposed.

Image on the left has lower bone density than image in the right

2 main processes by which bones form

state the role of osteoclasts and the epiphyseal plate

Intramembranous ossifcation - forms flat bones from fibrous membranes (eg forms the skull)

Endochondral ossification - forms most bones

Osteoclasts form the medullary cavity while the epiphyseal plate enables growth until maturity

Bone cells and their roles

Osteogenic cells

Osteoblasts

Osteocytes

Osteoclasts

Osteogenic cells - stem cells which divide and differentiate into osteoblasts

Osteoblast - build bone

Osteocytes - primary cell of the bone

Osteoclasts - break bone down

How bones heal

Stage 1 - a blood clots at the site, inciting inflammation (temporary scaffolding)

Stage 2 - soft callus hardens into a hard callus which closes the fracture gap

Stage 3 - the hard callus is remodelled into mature bone

Factors affecting bone healing (will be in exam)

Most to least important

Vascular integrity

Location

Type of fracture

Age

Metabolic factors

Osteoporosis - what is it and what causes it?

Radiographic appearance

A metabolic diseases which reduces bone mineral density, reducing it’s strength - mostly in older people

Radiographic appearance - The bone has a thinner cortex and larger trabecula.

Patient presentation for osteoporosis - physical signs and symptoms

Physical Signs

• Kyphosis/Hunchback

• Back pain

• Loss of height

Symptoms

• sudden fractures

• Back pain

• Weak grip strength

How can osteoporosis be imaged and which areas are looked at to assess bone density?

T-score diagnoses

DEXA scan - spine, forearm, left hip

T-scores

Normal between +1 and -1

Osteopenia between -1 and -2.5

Osteoporosis -2.5 or less

Osteomyelitis - what is it and what is it caused by?

Radiographic appearance

Inflammation of the bone caused by bacterial infection - often seen in diabetic patients

Radiographic appearance

• Lower bone density

• Lytic lesions - dark areas of bone with ‘moth-bitten appearance’

Patient presentation for osteomyelitis - physical signs and symptoms

Physical signs

• swollen, warm and tender limbs

Symptoms

• pain

• Limping

• Refusal to weight-bear

Which imaging methods can be used diagnose osteomyelitis?

CT, MRI, X-ray, Ultrasound

What is osteogenesis imperfecta and what causes it?

Radiographic appearance

A genetic mutation causing underproduction of collagen, resulting in brittle bones

Radiographic appearance

• decreased bone density

• Bowing of the bones

• Frequent and unexplained deformities leading to deformations

Patient presentation for osteogenesis imperfecta - physical signs and symptoms

Physical signs

• Bowed legs

• Short stature

Symptoms

• fragile bones which fracture easily

• Loose joints (hypermobility)

• Muscle weakness

Which imaging method can be used to diagnose osteogenesis imperfecta?

X-ray

Osteomalacia - what is it and what causes it?

Radiographic appearance?

‘Soft bone’ - caused by vitamin D, calcium or phosphate deficiency

Radiographic appearance

• incomplete fractures

• smudgy/erased looking trabeculae due to decreased bone density

• Looser zones (pseudofractures) appearing as lucent bands in the femoral neck

Patient presentation for osteomalacia - physical signs and symptoms

Physical signs

• bowed legs

• Waddling walk

• Dull persistent bone pain

Symptoms

• muscle weakness

• Cramps

• Fatigue

Which imaging methods can be use to diagnose osteomalacia?

CT, MRI, PET and X-ray

Osteosarcoma - what is it and what causes it?

Radiographic appearance?

Malignant bone cancer caused by genetic mutation. It is aggressive and can metastasize.

Radiographic appearance

• can appear totally sclerotic (dense)

• Lytic lesions

Patient presentation for osteosarcoma - physical signs and symptoms

Physical signs

• lump near joint

• Warmth

• Easily brushing

• Limping

Symptoms

• weight loss

• Fever

• Persistent bone pain

• Fatigue

What can be used to diagnose osteosarcoma?

CT, MRI, PET and X-ray

Preventing osteoporosis

Limit alcohol intake

Stop smoking

Take calcium and vitamin d supplements

Walk or jog regularly

Osteoporosis risk factors

Overconsumption of alcohol

Smoking

Lack of exercise

Lack of vitamin d and calcium

Poor diet

Genetics

Hormones