Session 1: Joint Pathology

Synovial joint features

1) Capsule

Fibrous Outer Membrane

Inner Synovial Membrane

2) Synovial Fluid

3) Hyaline cartilage

4) Other Structures

Ligaments

Menisci

Bursae

Tendons

Osteoarthritis

Degenerative disorder of synovial joints

Primary OA

Idiopathic

Secondary OA

Related to trauma, congenital abnormalities, infection, or necrosis

Risk factors for OA

Non-modifiable

Age

Female

Genetics

Joint misalignment

Modifiable

Obesity

Exercise/occupational stress

Muscular weakness

Presentation of OA

- Pain at end of day

- Older people

- Crepitus

- ↓ ROM

- Morning stiffness only lasts <30 min

- Bouchard and Heberden nodes

Investigations OA

Routine x-ray of the affected joints is not usually needed to confirm diagnosis

Consider arranging x-ray (depending on clinical judgement)

X-ray (weight bearing)

Loss of joint space

Osteophytes

Subchondral cysts

Subchondral sclerosis

First and second line of management for OA (according to NICE guidelines)

First Line

- Education

- Therapeutic exercise

- Weight loss

- Adjuncts: medication (NSAIDs, PPIs), manual therapy for hip/knee OA

Second Line

- Corticosteroid injection

- Surgical interventions: partial/total joint replacement, joint preservation surgery (e.g., debridement)

Which joints are commonly affected in OA

Proximal interphalangeal joints (PIP)

Distal interphalangeal joints (DIP)

Deformities of OA

Heberden's at DIPs

Bouchard's nodes at PIPs

Rheumatoid Arthritis (RA)

Chronic, systemic, inflammatory disease affecting the synovial membranes (inflammation) of multiple joints, eventually resulting in crippling deformities

Production of autoantibodies, pathogenesis not fully elucidated. Autoimmune disease.

Risk factors RA

FHx

Female

Obesity

Heavy smoker

Presentation RA

Symmetrical pain

Swelling

Warm joints (erythema)

Stiffness

Symptoms better with activity

Stiffness is worst in morning (>1hr waking)

Poor function

Which joints are most commonly affected in RA

Metacarpophalangeal joints

Carpometacarpal joints

Signs of RA

SWELLING / DEFORMITITES = LOOK WARM / TENDER / EFFUSIONS = FEEL

STIFFNESS / REDUCED ROM = MOVE

DIFFICULT FIST FORMING / PAINFUL MCPJ SQUEEZE = SPECIAL TESTS

RHEUMATOID NODULES / SYSTEMIC FEATURES / VASCULITIS / SCLERITIS = EXTRA-ARTICULAR FEATURES

Specific deformities of RA

Special test for RA

Positive (painful) metacarpophalangeal joint squeeze (MCPJ) test

Clinically suspected arthralgia score of >4 in any of the following is considered high-specificity for RA...

1) Joint symptoms with onset in last year

2) Symptoms involving MCP joints

3) Morning stiffness (>1hr)

4) Positive squeeze test on MCP joints

5) Difficulty forming fist

6) First-degree relative with RA (FHx)

Investigations for RA

Blood tests

Anti-cyclic citrullinated peptide antibodies

Rheumatoid factor

ESR, CRP, FBC

Imaging

X-ray: narrowed joint space

Soft tissue swelling

Subluxation

Marginal erosions

Function

Health assessment questionnaire

Disease activity score

Management of RA

The aim of management of RA is to manage pain, improve functioning & prevent deformities

Primary care

- Low dose NSAIDs

- Rheumatology referral

Secondary care

- 1st line = oral methotrexate DMARDs & bridge with corticosteroids

- 2nd line = biologics

Surgical referral

- Acute tendon rupture

- Infection

- Correcting deformities

Osteoarthritis vs Rheumatoid Arthritis

Gout

Acute inflammation as result of monosodium urate crystals accumulating in the joint. Urate is a purine metabolite excreted by renal and GI systems.

Risk factors for gout

- FHx

- CKD

- Diabetes

- Hypertension

- Diet (alcohol, meat, seafood)

- Obesity

- Age

- Male > female

Presentation of gout

Acute onset (overnight usually)

Severe pain, red, hot, swollen joint

Usually monoarticular

Often affecting metatarsal phalangeal joint

Differential diagnosis of gout

Pseudogout: deposit of calcium pyrophosphate crystals

Investigations for gout

Blood tests

- Blood urate >360 micromol/L

Joint aspiration

- MCS, gram-stain

- Crystal analysis = needle-shaped, negatively bifringent for urate crystals

- Do not aspirate if joint is prosthetic (refer to ortho)

Management of gout

- Medications to help excrete uric acid

- Ice on area

- No weight bearing

- NSAIDs e.g., Naproxen (+PPI) colchicine, oral corticosteroids

- Education

- Low purine (protein) diet and increased fluids

Septic arthritis

Inflammation of the joint caused by infection

Name some causes of septic arthritis in neonates

S. aureus

N. Gonorrhoea

Group B Strep

Name some causes of septic arthritis in children

S. aureus

Name some causes of septic arthritis in adults

S. aureus

N. Gonorrhoeae

S. Pneumoniae

Pseudomonas (trauma/puncture wounds)

Salmonella in sickle cell

Pathophysiology of septic arthritis

Irreversible joint damage within 6 hours

Organism releases chondrocyte proteases

Host inflammatory response

Medical emergency

Risk factors of septic arthritis

Abnormal joint: OA, RA, prosthetic joint, Gout

Age > 80

DM

IV drug abuse, alcoholism

Intra-articular glucocorticoid injections

Presentation (Hx) of septic arthritis

Acute onset

Monoarticular (knee = adults, hip in children)

Pain, swollen, red, warm joint

Systemic symptoms = fever, rigors, myalgia and malaise

Investigations for septic arthritis

Blood tests

FBC, CRP, ESR, blood cultures

Micro: MCS, gram stain, crystal analysis, WCC

STI screening

Urine/vaginal swab/throat swab/rectal swab NAATs

Imaging

X-ray

Kocher criteria

Used to distinguish septic arthritis (SA) from transient synovitis in children with hip pain

Each positive increases the likelihood of septic arthritis

- Non-weight bearing

- Temperature >38.5

- ESR >40

- WCC >12

Management of septic arthritis

Flucloxacillin + Gentamicin

Review antibiotics with culture results

4-6 weeks in total

Other differentials for arthralgia (joint pain)

Psoriatic arthritis

- Psoriasis

- Nail changes

- Enthesitis

- Dactylitis

Reactive arthritis

- Previous GI/GU infection

- Urethritis

- Conjunctivitis

Autoimmune connective tissue disorders

- SLE

- Sjogren's

Tendonitis

Inflammation of tendon

Bursitis

Inflammation of bursa from trauma, infection, crystalopathy, inflammatory arthropathies

Labral tear

Tear of the fibrocartilage glenoid labrum or the acetabular labrum from the bone