Locomotor

Question 1

What zones are in the growth plate?

What happens in each zone?

Answer 1

Proliferation zone
(cell division)

Resting zone (differentiation)

Hypertrophic zone (mineralisation)

Question 2

What are some ways to treat leg length discrepancy in children?

Answer 2

Epiphyseodesis - using curette to ablate part of the growth plate.

Using an 8-plate and pins - good for vargus (bowlegs) or valgus (kneeknock) deformities.

Question 3

What are Harris growth arrest lines?

Answer 3

Lines of increased bone density visible on radiograph that represent the position of the growth plate at the time of insult and formed on long bones due to growth arrest.

Can estimate age at which they were formed, often as a result of juvenile malnutrition, disease or trauma but can be due to normal growth spurts.

Question 4

What is the Ilizarov technique?

Answer 4

Treatment for Paget’s disease – (genetic skeletal disease causing bone weakening).

Uses an external frame for limb lengthening and straightening.

Question 5

What is a skier’s thumb?

Answer 5

Torn ulnar collateral ligament.

Question 6

What are the causes of osteoporosis?

Answer 6

Primary causes - bone resorption increase compared to deposition due to age, menopause (loss of oestrogen so increased osteoclast recruitment, decreased Ca absorption)

Secondary causes - endocrine, malnutrition, immobilisation.

Question 7

What is osteoarthritis?

Answer 7

Pain and stiff joints, initially episodic then continuous.

Age and obesity correlations and genetic predisposition

Biological basis - long-term, low grade inflammation - leads to cartilage loss, bone re-modelling and progressive joint degeneration.

No effective treatment - pain relief, NSAIDs (disease-modifying OA drugs in development)

Knee/hip arthroplasty, 85-90% prosthetic joints last 15-20 years. Revision common for loosening/’metalosis’.

Question 8

What is the Charnley hip-op?

Answer 8

Principles of the modern hip arthroplasty - total hip replacement.

Question 9

What is rheumatoid arthritis?

Answer 9

Long-term condition causing pain, swelling, stiffness of joints .

Inflammatory autoimmune disease - immune system attacks synovial cells, increasing inflammatory mediators, causing cartilage and bone destruction.

Genetic and environmental factors - can affect any age.

Rheumatoid factor (RF - an autoantibody) has systemic effects on other tissues (inflammation in around lung, heart, dry eye…)

Pain medications, steroid, NSAIDs; diseases modifying anti-rheumatic drugs slow progression (hydroxychloroquine, methotrexate…).

Question 10

Why is repair of connective tissue from so poor?

Answer 10

Poor vascular supply
Limited supply of nutrients
Very low synthesis rates of some tissue components Loss of cell-matrix interactions – leads to irreversible loss of phenotype
Integration of repair tissue very poor
Mechanical properties of repair tissue inferior/weak

Question 11

Describe the sliding filament theory.

Answer 11

During muscle contraction, actin is pulled in towards myosin.

Thin band proteins are actin.
Thick band proteins are myosin.

This makes a tiny contraction but this adds up so longer muscle means larger contraction.

Question 12

What are the types of bones?

Answer 12

Flat (sternum), irregular (vertebrae), long (femur), short (carpals), sesamoid (patella)

Question 13

What is the anatomy of bones?

Answer 13

Bone is not ‘static’/inert but metabolically active, under constant renovation.

Mixture of organic and inorganic compounds - mineral to make hard: hydroxyapatite (calcium phosphate), organic to make slightly flexible and stronger: collagen (mainly type I)

Stores Ca and can release into body if needed.
Matures white blood cells and makes red blood cells.

Question 14

What are the two types of bones?

Answer 14

Cortical/compact - rigid, tightly packed, formed of cylindrical structures (osteons).

Trabecular/spongy/cancellous - loosely arranged struts, inside bones to keep lighter and allow ends of bones to be more dynamic.

Question 15

What is the histology of bones?

Answer 15

Made of osteons which are cylindrical units made of rings of lamellae, aligned parallel to the long axis of the bone. At the centre of the osteon is the Haversian canal with blood vessels. Osteocytes lie between lamellae in spaces called lacunae.

Question 16

Describe the two types of bone development.

Answer 16

2 types:
Intramembranous - forms directly in soft tissue (mesenchyme)
Endochondral - cartilage template forms first.

Question 17

Describe Endochondral Ossification.

Answer 17

Bones form in stages;

Primary ossification centre (in-utero)
Secondary ossification centre (post-natal)

Growth plates separate these areas - cartilaginous region

Question 18

Describe how the shape and structure of muscles are relevant.

Answer 18

Form affects function:

Mass (amount of muscle) = magnitude (strength)

Arrangement of fascicles (feathering, heads…) = direction of action

Length of fibers = range of motion (how far it moves)

Question 19

What do agonist muscles do?

Answer 19

Provide the active movement.

Question 20

What do synergist muscles do?

Answer 20

Complement the active movement (agonist muscles) by supporting, guiding or providing more power.

Question 21

What do antagonist muscles do?

Answer 21

Opposes or counters agonist to unflex it, control the movement, or hold half-flexed.

Question 22

What do fixator muscles do?

Answer 22

Reduce movement in other nearby muscles you don’t want to move.

Question 23

What are the types of joints?

Answer 23

1. Fibrous joints (fibrous tissue)
2. Cartilaginous joints (cartilage)
3. Synovial joints (tube of fibrous tissue)

The first two are solid joints - don’t have that much movement (but can undergo synostosis sometimes).

The third (synovial) is cavitated joints - can move.

Question 24

What are the types of fibrous joints?

Answer 24

2 types:

1. Syndesmosis
   - ligament/membrane like interosseous membrane between radius/ulna, and inferior tibiofibular joint
2. Suture/sutural ligament - skull (inter-frontal suture normally undergoes synostosis/fuses by 6th year, but persistent metopic suture in 8%), and gomphosis peg and socket (tooth)

Question 25

What are the primary and secondary types of cartilaginous joints?

Answer 25

2 types;

1. Primary (synchondrosis) - unossified cartilage (epiphyseal cartilage, costal cartilage…); includes growth plates which disappear with age
2. Secondary (symphysis) - only in midline; 3 layer structure (hyaline plate-fibrocartilage-hyaline plate), (intervertebral disc, pubic symphysis)

Includes intervertebral discs with nucleus and annulus fibrosis

Thoracic cage has primary cartilaginous joint between sternum and ribs and secondary in midline

Question 26

What are the general features of a synovial joint?

Answer 26

1. Capsule (capsule ligaments)
2. Cavity
3. Synovial membrane
4. Articular cartilage
5. Ligaments
6. Movement

But there are atypical synovial joints - temporomandibular, sternoclavicular, acromioclavicular, sacroiliac; these are covered by fibrocartilage with incomplete discs.

Question 27

What are the intra-articular structures found in synovial joints?

Answer 27

1. Fat pads - spread out synovial fluid within joint)
2. Discs/menisci - fibrocartilage, incomplete/complete discs, splits joint into compartments/shock absorption
3. Labra - fibrocartilage, deepens joint surface for stability

Ligaments - within joint are to stabilise but not strong

Tendons - within joint like popliteus/long head biceps

Question 28

What are the two ways synovial joints can be classed?

Answer 28

Axes of movement: uni-axial, bi-axial, multi-axial

Shape of surfaces: homo-morphic, hetero-morphic

Question 29

How are synovial joints classified by the axes of movement?

Answer 29

Transverse axis - flexion/extension

Antero-posterior axis - abduction/adduction

Longitudinal axis - rotation

A joint can be uni-axial, bi-axial, multi-axial.

Question 30

How are synovial joints classified by shape of joint surfaces?

Answer 30

Homomorphic - plane, saddle

Heteromorphic: hinge, pivot, ellipsoid, ball & socket, condyloid

Question 31

What factors contribute to stability of joints?

Describe the trade-off experienced.

Answer 31

Bony, ligamentous, muscular factors (think about in that order).

Trade off between stability and mobility.

Question 32

How do synovial joints get their blood supply?

Answer 32

Blood supply - supplied by circulus vasculousus (arterial circle). Different in children and adults;

In children growth plate separates metaphysis and epiphysis
Metaphysis - blood supply from nutrient artery old (end artery)
Epiphysis - blood supply from circulus vasculousus

In adults, blood can flow between metaphysis and epiphysis so has single supply of the circulus vasculousus.

Question 33

What is Hilton’s Law?

Answer 33

The nerves that supply the muscles acting on a joint also supply the joint and the overlying skin.

This can lead to referred pain as some muscles act on multiple joint.

Question 35

Describe a tension pneumothorax.

Answer 35

Penetrating trauma makes whole in chest wall so air can be drawn into the thoracic cavity when patient breathes in, but seals shut when patient breathes out (like valve).
This creates buildup of pressure on mediastinum, pushing it over to the other side, compressing other side of the chest, decreasing venous return to the heart as pressure rises equal to great veins, leading to cardiac arrest.

Question 36

How do you identify a tension pneumothorax?

What is the treatment?

Answer 36

Decreased breath sounds on affected side, increased percussion note (hyper-resonant), engorged neck veins, reduced lung expansion, deviation of trachea to opposite side due to mediastinal shift.

High flow oxygen and needle decompression (2nd intercostal space/midclavicular line for children, 5th intercostal space/midaxillary line for adults), then definitive chest drain inserted (same location).

Question 37

What is an open pneumothorax?

How would you treat it?

Answer 37

Severe injury penetrating the lung; ‘sucking chest wound’, air passes into cavity through path of least resistance (which is now directly the chest) and exhales via this route (trachea not used) unable to properly oxygenate blood and breathing is ineffective.

Treat with oxygen and three-sided occlusive dressing (allows air out but not in). Definitive chest drain (4th or 5th intercostal space/midaxillary line.

Question 38

What is flail chest?

What is the treatment?

Answer 38

2 or more ribs fractured in 2 or more places, seperating a segment of thoracic cage that is unable to contribute to lung expansion.

Paradoxical movement of segment (drawn inwards as rest of ribs move out during inhalation). Effective ventilation prevented and underlying lung injuries like contusions/hemopneumothoraxes are common.

Fix fractures with plate and screws.

Question 39

What is problem with pelvic fractures related to circulation?

How can you prevent this?

Answer 39

Can be haemorrhagic and result in exsanguination.

Need to ‘close the book’ with a binder.

Question 40

What circulatory issue can arise from cardiac tamponade?

How can we deal with this?

Answer 40

Pericardium (fixed sac around heart) has small pressure increase due to blood.

This has a big effect, causing inability to pump during systole/dilate to fill during diastole.

Need to do a pericardiocentesis.

Question 41

What circulatory issue can arise from a massive haemothorax?

How can we deal with this?

Answer 41

Hemorrhagic condition can result in >1500mls blood in pleural cavity.

Need to give chest drain, blood products and cardiothoracic surgery.

Question 42

What is shock?

Answer 42

End-organ dysfunction due to inadequate oxygen delivery to tissues (perfusion). Cardiac, gut, brain, renal…

Delivery decreases due to anaphylactic, cardiogenic, haemorrhagic, neurogenic reasons - can’t meet demand.

Or demand increased too much for delivery - sepsis.

Question 43

What is haemorrhagic shock?

Answer 43

Normally trauma, body’s balance between blood loss and compensation fails.

Four classes based on blood volume:
i. <15%
ii. 15-30%
iii. 30-40%
iv. >40%
(circulating volume normally around 5L)

Question 44

How do you treat hemorrhagic shock?

Answer 44

Stop the bleeding.

Give blood products (RBCs, platelets, FFP), tranexamic acid (promotes clotting).

Permissive hypotension (low BP better in trauma - just enough to keep cerebral perfusion, not enough to start bleeding again, roughly 80mmHg systolic).

Question 45

What are the measures for disability?

Answer 45

GCS - best response eye opening, verbal, motor; total out of 15.

AVPU scale - alert, verbal, pain, or unresponsive

Temperature, blood glucose.

Question 46

What is the pneumonic for life-threatening trauma?

Answer 46

ATOMFC:

Airway obstruction
Tension pneumothorax
Open pneumothorax
Massive haemothorax
Flail chest
Cardiac tamponade