L13 Introduction to diseases of the MSK system

Question 1

Prefix - problems with bones

Answer 1

Osteo

Question 2

Prefix - problems with muscle

Answer 2

My/Myo

Question 3

Prefix - problems with joints

Answer 3

Arth

Question 4

Prefix - describes cartilage

Answer 4

Chond

Question 5

Bursitis

Answer 5

• Inflammation of bursa. Bursae are synovial membrane lined pockets that serve to allow free movement of adjacent structures where otherwise, there could be friction

Question 6

Enthesitis

Answer 6

• Inflammation of an enthesis. Entheses are the points where tendons, ligaments or joint capsules insert into bone
• The largest site is the achilles insertion

Question 7

Osteoporosis

Answer 7

• Reduced bone density

Question 8

Osteomalacia

Answer 8

• Poor bone mineralisation

Question 9

Osteomyelitis

Answer 9

• Bone infection

Question 10

Osteosarcoma

Answer 10

• An example of malignant bone tumour

Question 11

Myalgia

Answer 11

• Pain in muscles
• Very common
• Commonly associated with viral infections
• Can be drug induced (eg by statins)

Question 12

Myositis

Answer 12

• Inflammation of the muscles

- Far less common than myalgia and can be autoimmune

Question 13

What is a joint

Answer 13

• Formed where two or more bones meet each other

Question 14

Approach to a patient with MSK disorder

Answer 14

• Full history
• Physical examination
• Serological tests - help to support the diagnosis

Question 15

Some ways of classifying rheumatic disease

Answer 15

• Articular vs non articular/periarticular
• Inflammatory vs non- inflammatory/degenerative/mechanical
• Duration of onset

Question 16

What should be suspected in acute monoarthritis

Answer 16

• Infection

Question 17

Periarticular vs articular joint pain

Answer 17

Periarticular:
- Point tenderness over the involved structure, pain reproduced by movement involving that structure

Articular:
- Joint line tenderness, pain at the end range of movement in any direction

Question 18

Structures affected by periarticular joint pain

Answer 18

• Bursa
• Tendon
• Tendon sheath
• Ligament
• others

Question 19

What to look for if articular joint pain

Answer 19

• Any signs of inflammation

- Features of mechanical problem (locking, catching etc)

Question 20

Joint inflammation nomenclature

Answer 20

• Monoarthritis - arthritis affecting 1 joint
• Oligoarthritis - arthritis affecting 4 or fewer joints (2-4)
• Polyarthritis - arthritis affecting 5 or more joints(>=5)

Question 21

Soft tissue conditions

Answer 21

• Problems with radiolucent moving tissues

- Very common

Question 22

Examples of soft tissue conditions

Answer 22

• Tennis elbow (lateral epicondylitis)
• Golfers elbow (medial epicondylitis)
• Carpal tunnel (median nerve compression as it passes through the carpal tunnel in the wrist)

Question 23

Importance of rheumatic disease

Answer 23

• Common and getting more common
• Expensive
• Leading cause of disability

Question 24

Septic arthritis - differential diagnosis

Answer 24

• Differential diagnosis of hot swollen joint is wide

- Always consider joint aspiration and gram stain

Question 25

What can increase the possibility of a diagnosis being septic arthritis

Answer 25

- Always think about it in a patient with a (usually) single, hot and swollen joint - They do not have to be systemically unwell and they may be able to weight bear

Question 26

Most common organisms - septic arthritis

Answer 26

- Staph and strep

Question 27

Gout

Answer 27

- Most common inflammatory arthropathy worldwide - Serum urate levels > physiological saturation point (around 408 micromol/L) - Form and deposit cartilage, bone, and periarticular tissues of peripheral joints

Question 28

Who gets gout

Answer 28

- Men aged 40 years and over - Women over 65 years - It increases with age, affecting 15% of men aged over 75 in the UK

Question 29

Conditions associated with gout

Answer 29

- Metabolic syndrome and its components (insulin resistance, obesity, hyperlipidaemia, and hypertension)

Question 30

Risk factors for gout

Answer 30

- Male sex - Older age - Genetic factors (mainly reduced excretion of urate) - Chronic kidney disease(reduced excretion of urate) - Loop and thiazide diuretics(reduce excretion of urate) - Osteoarthritis(enhanced crystal formation) - Dietary factors(increased production of uric acid)

Question 31

Crystals in gout

Answer 31

- Gout is caused by negatively birefringent rods (monosodium urate) - Pseudogout (CPPD) by positively birefringent rhomboids - calcium pyrophosphate

Question 32

Management of gout

Answer 32

Acute attacks: - NSAIDs eg naproxen - Colchicine - Steroids Long term: - Urate-lowering therapy eg, allopurinol or febuxostat

Question 33

Rheumatoid arthritis

Answer 33

- Common, chronic, multisystem inflammatory condition affecting up to 0.5-1% of the world population - More common in women (3:1) - Peak onset is 45-65 years - Unknown cause with around 30% genetic susceptibility and the rest environmental

Question 34

Main problem in inflammatory arthritis vs osteoarthritis

Answer 34

- The main problem in inflammatory arthritis is with the synovium whereas in osteoarthritis, the main problem is with the cartilage

Question 35

Classification and disease duration - 'Normal'

Answer 35

Phase A/B - Genetic and environmental risk factors Phase C - Systemic autoimmunity Induction of autoimmunity

Question 36

Classification and disease duration - 'symptoms'

Answer 36

- symptoms - Phase D - Maturation of the antibody response 0-3 months from symptom onset

Question 37

Classification and disease duration - Swelling

Answer 37

- Unclassified arthritis - Swelling - Phase E 3-6 months from time of onset

Question 38

Classification and disease duration - Fulfilment of classification criteria

Answer 38

- Rheumatoid arthritis - Phase F - No additional changes 6-9 months from time of onset

Question 39

Rheumatoid arthritis pathophysiology

Answer 39

- Early lymphocyte invasion of the synovium - Acute inflammatory reaction - swelling and increased vascular permeability - Synovial proliferation - Pannus formation - Cartilage destruction and bone erosion

Question 40

Symptoms and signs of rheumatoid arthritis

Answer 40

- Onset varies, can be acute or chronic - Symmetrical pain and boggy swelling of the small joints of the hands and feet (MCP, PIP, wrist, MTP, subtalar, NOT the DIPs) - Early morning stiffness > 1 hr - Malaise and fatigue are common - Systemically unwell - Examination (look for pain, swelling and restriction of movement) - Also really important to examine other organ systems as RA is a systemic disease

Question 41

Extra-articular manifestations of RA

Answer 41

- Nodules(20%) - Bursitis/tensosynovitis - Eyes - dry eyes(secondary sjogren's syndrome)/scleritis/scleromalacia - Splenomegaly (felty's) - Anaemia of chronic disease - Lung fibrosis/effusion/nodules (caplan's) - Pericarditis - Neurological - atlanto-axial subluxation/ carpal tunnel syndrome/ mononeuritis multiplex - Renal amyloidosis - Leg ulcers/pyoderma gangenosum - Vasculitis - Increased risk of cardiovascular disease

Question 42

RA investigations

Answer 42

- ESR and CRP - FBC - Anaemia of chronic disease (normochronic normocytic) - Rheumatoid factor positive - IgM antibody against the Fc portion of human IgG antibodies (can be falsely elevated by illness, normal raised levels in 1 in 20 of population) - Anti CCP antibodies - cyclic citrullinated peptide antibodies - antigen present on inflamed synovium(98% specific for diagnosis of RA) - X-rays: normal in early disease...erosions/peri-articular osteoporosis and reduced joint space/ cysts

Question 43

RA principles of management 1

Answer 43

- Early and aggressive treatment to reduce inflammation and joint damage - Non-steroidal anti-inflammatory drugs for short periods - Corticosteroids (intra-articular joint injections if only 1 or 2 troublesome) - Systemic if many joints are a problem - The main routes are IM or PO though in severe disease, we may give IV steroid

Question 44

RA principles of management 2

Answer 44

- DMARDs - disease modifying anti-rheumatic drugs - Synthetic DMARDs - methotrexate, sulfasalazine, hydroxychloroquine, leflunomide - Biologic agents - anti TNF agents(Etanercept, adalimumab, infliximab), anti B-cell(rituximab), anti interleukin-6 receptor blocker (tociluzumab), anti T-cell - selective co-stimulation modulator - CTLA4-Ig (abatacept), Janus kinase inhibitor(JAK 2) (tofacinitib, baricitinib)

Question 45

RA principles of management 3

Answer 45

Multidisciplinary team input: - Nurse specialist(education and disease monitoring) - Physiotherapy (improve strength and stamina) - Occupational therapy (work, home environments) - Podiatry

Question 46

Osteoarthritis

Answer 46

- Common, degenerative disease of which the prevalence increases with age - Affects 70% of over 65 year olds - Most commonly clinically affects the knees, hips and small joints of the hands(DIP, PIP, 1st CMCJ) - Characterised by joint pain and very variable degrees of functional limitation

Question 47

Osteoarthritis pathophysiology

Answer 47

- Metabolically active, dynamic process involving all joint tissues(cartilage, bone, synovium, capsule, ligaments/muscles) - Focal destruction of articular cartilage - Remodelling of adjacent bone = hypertrophic reaction at joint margins(osteophytes) - Remodelling and repair process(efficient and SLOW) - Secondary synovial inflammation and crystal deposition

Question 48

Clinical features of osteoarthritis

Answer 48

- Age > 50 years - Morning stiffness < 30 mins - Persistent joint pain aggravated on use - Crepitus - No inflammation - Bony enlargement and/or tenderness

Question 49

OA investigations

Answer 49

- Blood tests not helpful - A clinical diagnosis - X-rays do not correlate well with symptoms

Question 50

RA vs OA

Answer 50

Synovial disease - cartilage disease Both bilateral and symmetrical MCPs and PIPs - DIPs and 1st CMCJs(humb bases) Stiffness in the morning > 30 mins - Can be stiff in morning but less significant Better after some activity (less stiff) - Worse on exertion and at the end of the day Raised inflammatory markers common - inflammatory markers not raised Extra-articular features may be present - is a joint disease Auto-immune - cause unknown but described to patients as 'wear and tear' Both have family history

Question 51

Systemic lupus erythematosus (SLE)

Answer 51

- Chronic, relapsing, remitting disease - Broad spectrum of clinical features involving almost all organs and tissues - Prevalence in the UK: 97 per 100,000 - Peak onset between 15-40 years - More common and severe in those of afro-caribbean, India, hispanic and chinese origin living in the USA and Europe > caucasians

Question 52

SLE pathophysiology

Answer 52

1. Genes C1q, C2, C4 HLA-D2,3, 8. MBL. FcR 2A, 3A, 2B, IL-10, MCP-1, PTPN22. Environment, UV light, gender and infection. 2. Abnormal immune response 3. Autoantibodies Immune Complexes 4. Inflammation - Rash, nephritis, arthritis, leukopenia, CNS dz, carditis, clotting --chronic inflammation and oxidation--> 5. Damage - Renal failure, atherosclerosis, pulm fibrosis, stroke and damage from Rx

Question 53

SLE - 2012 SLICC classification criteria

Answer 53

1) Acute cutaneous LE - malar rash, photosensitivity - positive ANA 2) Chronic cutaneous LE - dicoid rash - Anti - dsDNA 3) Oral or nasal ulcers - antiphospholipid antibodies 4) Nonscarring alopecia - low C3, C4, CH50 5) Non-erosive arthritis(jaccoud arthropathy) - direct coomb's test 6) Serositis 7) Renal disorder - 4/17 (at least 1 clinical) 8) Neruological disorder Haematological disorder: 9) Haemolytic anaemia 10) Leucopenia 11) Lymphopenia 12) Thrombocytopenia

Question 54

When is biopsy proven nephritis comparable with SLE

Answer 54

- In the presence of ANA antibodies or anti-dsDNA antibodies

Question 55

SLE investigations

Answer 55

Urinalysis - urinary protein:creatinine ratio FBC Urea and electrolytes ESR CRP Liver function test Antibodies: ANA; ENA; Anti-dsDNA; Lupus anticoagulant; Anti C1q; C3, C4

Question 56

Non-pharmacological management of SLE

Answer 56

- Sun protection - Smoking cessation - CVD RISK modification - Osteoporosis prevention

Question 57

Management of mild SLE

Answer 57

Mild(skin manifestations, arthritis) Treatment: HCQ or MTX +- CS(low dose)

Question 58

Management of moderate SLE

Answer 58

- Mild-to-moderate nephritis - Thrombocytopenia - Major serositis Treatment - Induction therapy - iv. MP(1 g/day for 3 days) followed by: AZA(2 mg/kg/day) or MMF(2-3g/day) GC(0.5-0.6 mg/kg/day for 4-6 weeks, then taper) Maintenance therapy - AZA(1-2 mg/kg/day) or MMF(1-2g/day), GC(0.25 mg/kg every other day)

Question 59

Management of severe SLE

Answer 59

- Severe nephritis (class IV, III + V, IV + V or III-V with renal impairment) - Severe refractory thrombocytopenia - Severe refractory hemolytic anaemia - Lung involvement (hemorrhage) - CNS(cerebritis, myelitis) - Abdominal vasculitis Induction therapy: iv. MP (1 g/day for 3 days) iv. CYC (1 g/m/month x 7 doses) Maintenance therapy: iv. CYC (1 g/m^2 every 3 months for 1 year) Add rituximab calcineurin inhibitors iv. IG