Summary MUSCULOSKELETAL MLA MAPPING - for Medical Exams and Finals

Septic Arthritis
Anatomy & Risks
Most common organism = staph aureus
- Sexually active young adults = N. gonorrhoeae
- Normally due to haematogenous spread
o Can be from distant bacterial infections e.g., abscesses
Most common location = knee
Risk factors
- IVDU
- DM/immunosuppression/PVD/alcoholism
- Older age
- Underlying joint injury/disease/prosthesis
- Unprotected sex
Can be presenting sign of endocarditis

Symptoms & Complications
- Acute, swollen joint
o Restricted movement
o Warm to touch/fluctuant
- Fever

Investigations
- Synovial fluid sampling
o Before abx
- Blood cultures
- Joint imaging
o MRI rule out osteomyelitis

Treatment/Management & Side effects
- IV abx covering G+ve cocci
o Flucloxacillin (clindamycin if pen allergy)
o 4-6wks (except gonococcal – 2wks)
o Typically switched to PO after 2wks
- Needle aspiration to decompress joint

,Reactive Arthritis
Definition & DDx
HLA-B27 associated seronegative spondyloarthropathy

Anatomy & Risks
Triad of
- Urethritis
- Conjunctivitis
- Arthritis
‘Can’t see, pee or climb a tree’
Post-STI more common in men (chlamydia)
- Other causes = post-dysenteric
o Shigella
o Salmonella
o Yersinia
o Campylobacter

Symptoms & Complications
Typically develops within 4wks initial infection
- Sx last 4-6mths
Arthritis
- Asymmetrical oligoarthritis of lower limbs
- Dactylitis
Urethritis
Eye
- Conjunctivitis
- Anterior uveitis
Skin
- Circinate balanitis (painless vesicles on coronal margin of prepuce)
- Keratoderma blenorrhagica (waxy yellow/brown papules on palms/soles)

Investigations

Treatment/Management & Side effects
- Analgesia
o NSAIDs, intra-articular steroids
- Sx rarely last ≥12mths
- If persistent disease
o Sulfasalazine and MTX

,Osteomyelitis
Definition & DDx
Staph aureus = most common cause
- Salmonella most common in sickle cell anaemia
DDx
- Septic arthritis
- Ewing sarcoma
- Cellulitis
- Gout

Anatomy & Risks
Classified into haematogenous: Non-haematogenous:
- Bacteraemia - Contiguous spread from adjacent
- Monomicrobial soft tissues/direct bone injury
- Most common classification in - Polymicrobial
children - Most common classification in
- Vertebral most common location in adults
adults - Risks
- Risks o Diabetic foot
o Sickle cell anaemia ulcers/pressure sores
o IVDU o DM
o Immunosuppression o PAD
o IE

Symptoms & Complications
Acute
- Fever
- Pain at rest, worsening with weight-bearing
- Swelling
- Erythema of affected site
Chronic
- Long hx pain
- Persistently draining sinus tract/wound
- Soft tissue damage
- Presence of risk factors

Investigations
- MRI
- Blood cultures

Treatment/Management & Side effects
- 6wks flucloxacillin
o Clindamycin if pen allergy
- Surgical debridement
o Chronic osteomyelitis
o Associated collections

, Gangrene (Wet and Dry)
Definition & DDx
Wet = infectious; Includes:
- Necrotising fasciitis (strep. Pyogenes)
- Gas gangrene (clostridium perfringens)
- Gangrenous cellulitis (immunocompromised)
Dry = ischaemic (due to chronically reduced blood flow)
- Atherosclerosis due to PAD
- Thrombosis due to vasculitis/hypercoagulable state
- Vasospasm due to cocaine/Raynaud’s

Anatomy & Risks
Dry = more common
- Elderly
- Smokers
- PAD
- DM

Symptoms & Complications
Wet
- Necrotic area poorly demarcated
- Fever
- Sepsis
Dry
- Well demarcated necrotic area
- No signs of infection
- Auto-amputation often occurs

Investigations
- FBC/ESR/CRP, blood cultures, BMs, coagulation profile
- XR/doppler/USS/CT
- Tissue biopsy for causative organism


Treatment/Management & Side effects
Wet
- Surgical debridement/amputation
- Broad spec IV abx
Dry
- Surgical debridement/amputation
o Depends on severity and extent of necrosis