Joints and Joint Problems

Question 1

What are the three types of joints?

Answer 1

Fibrous; bones connective with fibrous connective tissue (collagen fibres)

Cartilaginous; bones connected by cartilage

Synovial; joints articulating with synovial fluid

Question 2

What are some fibrous joints?

Answer 2

• Periodontal ligament
• Cranial sutures
• Interosseus membranes (i.e. between radius and ulna)

Question 3

What makes up a primary cartilaginous joint?

Answer 3

Only hyaline cartilage

i.e. synchondrosis (almost immovable between bones)

Question 4

What makes up a secondary cartilaginous joint?

Answer 4

Hyaline and fibrocartilage

i.e. symphysis intervertebrqal disc

Question 5

What are common features of a synovial joint?

Answer 5

• Synovial cavity (fluid-filled)
• Articular cartilage
• Fibrous capsule
• Synovial membrane

May also have

• articular discs
• ligaments
• bursae

Question 6

What are the subtypes of synovial joints?

Answer 6

• plane
• condylar (ellipsoid)
• hinge
• saddle
• pivot
• ball and socket

Question 7

Describe the arrangement of articular cartilage (hyaline)

Answer 7

Superficial/tangential layer; flattened chondrocytes that produce collagen and glycoproteins

Transitional layer; round chondrocytes that produce proteoglycans such as aggrecan

There is a change in collagen orientation from superficial to deep layers

> 75% water

Question 8

What layer of articular cartilage produces collagen and glycopreoteins?

Answer 8

Superficial layer

Produced by the flattened chondrocytes

Question 9

What layer of articular cartilage produces proteoglycans i.e. aggrecan?

Answer 9

Transitional layer

Produced by round chondrocytes

Question 10

What are glycoproteins?

Answer 10

e.g. lubricin

Proteins to which oligosaccharide chains are attached

i.e. more protein than carbohydrate

Question 11

What are proteoglycans?

Answer 11

e.g. aggrecan

Proteins that are heavily glycosylated (+ a protein core to which one or more GAGs attach)

i.e. more carb than protein

Question 12

What are glycosaminoglycans (GAGs)?

Answer 12

e.g. hyaluronic acid

Long unbranched polysaccharides, highly polar and thus attract water

Question 13

What is the general thicknesses of articular cartilage?

Answer 13

Average; 2-3mm

Interphalangeal joint; 1mm

Patella; 5-6mm

Question 14

Describe the synovium

Answer 14

Synovial membrane which produces the synovial fluid

Synoviocytes produce the fluid

Rich capillary network

No epithelial lining

Direct exchange of oxygen, CO2, metabolites between blood and synovial fluid

Question 15

Describe type A synoviocytes

Answer 15

Look like macrophages

Remove debris

Contribute to synovial fluid production

Question 16

Describe type B synvoviocytes

Answer 16

Fibroblast like

Main producer of synovial fluid

Question 17

Describe synovial fluid

Answer 17

Viscous fluid, hyaluronic acid and lubricin, fluid component form blood plasma

Small volumes; knee joint ).5ml)

Rapid turnover ~2hours

Question 18

What are the functions fo synovial fluid?

Answer 18

Nutrition of cartilage (articular c, menisci/discs)

Removal of waste products

Lubrication - less friction - less wear

Question 19

Describe joint lubrication

Answer 19

Boundary; glycoproteins i.e. lubricin bind to receptors on articular surfaces to form thin film

Hydrodynamic; surfaces kept apart by liquid pressure, viscosity changes with load and velocity of movement

Weeping; fluid that is present in cartilage squeezed out into synovial cavity to increase fluid vol

Question 20

Describe the effect of ageing on joints

Answer 20

Viscosity of synovial fluid increases; slower joint movement and reduced lubrication

Water content of cartilage decreases; reduced shock absorption

These cause less protection of articular surfaces and increased risk of damage

Question 21

Describe the pathologenesis of osteoarthritis

Answer 21

Trauma and mechanical imbalance

Inflammation and pain

Repair processes around the joint

Question 22

How is osteoarthritis diagnosed?

Answer 22

45+ years

Activity related joint pain + either no morning joint stiffness or morning stiffness lasting no longer than 30mins

ATTENTION! Trauma, prolonged morning-related stiffness, rapid deterioration of symptoms, hot swollen joint

Question 23

What are possible differential diagnoses in osteoarthritis?

Answer 23

• gout
• other inflammatory arthritis
• septic arthritis
• malignancy

Question 24

What is the investigation for suspected OA?

Answer 24

Generally X-Ray to confirm clinical diagnosis

Question 25

Describe the management of OA

Answer 25

Non-pharmacological

• thermotherapy
• electrotherapy
• aids and devices
• manual therapy
• NICE don’t recommend acupunture, nutraceuticals

Pharmacological

• oral; paracetamol, NSAIDs
• topicals; NSAIDs, capsaicin
• intra-articular injection; steroid

Surgery if substantial impact on QoL

Question 26

How are hip fractures classified?

Answer 26

Intracapsular
- edge of femoral head to capsule of hip joint

Extracapsular
- trochanteric/subtrochanteric (lesser trochanter is division line)

GARDEN system is one classification method

Question 27

Describe the treatment of an undisplaced intracapsular hip fracture

Answer 27

Internal fixation or hemiarthroplasty if unfit

Question 28

Describe treatment of a displaced intracapsular hip fracture

Answer 28

young and fit i.e. <70yrs : reduction and internal fixation

Older and reduced mobility: Hemiarthroplasty or total hip replacement if fit

Question 29

Describe treatment of an extracapsular hip fracture

Answer 29

dynamic hip screw

If reverse oblique, transverse or subtrochanteric : intramedullary device