Download Orthopaedics 4 – Osteoarticular Infections

Orthopaedics 4 – Bone and Joint Infections
Anil Chopra
1. Describe the natural causes of infection; septic arthritis and osteomyelitis
2. Outline the iatrogenic causes of infection following implants
There are 3 common bone and joint infections:
• Septic arthritis
• Prosthetic joint infection
• Osteomyelitis
Blood supply of the bones:
 10-20% of CO
 Long bone (3 routes):
o Nutrient artery – most important source of arterial blood
o Periosteal arteries – supply outer layer of cortical bone
o Epiphyseal arteries
 Short, flat, irregular bone: superficial supply and nutrient artery
Rich supply of blood to areas of red marrow (<18yrs – long bone diaphysis, adulthood
– flat bones
Septic Arthritis
Septic arthritis is the infection of a joint.
Pathogenesis:
- The infection can spread in the blood
- Can occur as a result of a complication with a diagnostic or therapeutic procedure.
- In children it can be an extension of metaphyseal osteomyelitis.
- Normally occurs at the knee and hip joints.
- Common pathogens include
o 0-3months: S. areus . B streptococcus (E. Coli N. Gonorrhoea)
o 3-14 yrs: S. areus, Streptococcus pyrogens, Strep. Prenumonae H.
influenza
o 15-40 yrs: N. gonorrhoea, Streptococci, gram-negative bacilli
o 40+ yrs: Staph Aureus most common organism
o Chronic mono-articular septic arthritis: Brucella, Nosodia, Micro-bacteria
fungi
o Chronic polyarticular: Borrelia burgdorfei
Symptoms:
- Hot, red, swollen joint
- Fever
Complications:
- impaired range of movement
- pain
Tests:
- FBC, U&E, CRP, Blood cultures
- Aspiration
o Microscopy
o Culture
- Gram stain
- ZN stain for TB
- Arthroscopy
Management:
- wash out the pus from the joint
- intensive care
- antibiotics
- Rest
- Analgesic
Prosthetic Joint Infection
Pathogenesis:
- if it occurs in less than 2 years of having the prosthetic joint, then the pathogen
is likely to have come about as a result of surgery
- if it occurs in more than 2 years of having the prosthetic joint, then the
pathogen is likely to have spread haematogenously
- normally caused by coagulase negative staphylococci
Symptoms:
- pus discharge from infected joint
Management
- Surgical debridement (removal of dead, damaged or infective tissue)
- Intravenous antibiotics (vancomycin)
Osteomyelitis
Osteomyelitis is an infection of the bone itself.
Classical Acute Osteomyelitis
Pathogenesis
- infection arises in metaphysis.
- Spreads in blood
- People with sickle cell anaemia are vulnerable
- Longer bones normally affected
Pathophysiology of Hematogenous Seeding
When under pressure, exudates or abscess can extend through Volkmann canals into
subperiosteal region, and from there into medullary cavity or epiphysis.
Acute Haematogenous Osteomyelitis/ Septic Arthritis:
Detail history:
 Neonates – birth trauma, premature baby who needed invasive support treatment
(NICU)
 Children – antecedent URT infection, trauma (1-2% of ostemyelitis from puncture
wound through sole of trainer)
 Adult – STD, IV drug users
 Elderly – Recurrent bacteraemia from distant source (UTI)
Symptoms:
- bone dysfunction (limping)
- Pain
- Tenderness
- Fever
- Disability
- Deformity
Involucrum
Sequestrum
Septic
Arthritis
Investigations:
- bone scan – shows hotspots
- Ultrasound: Sub periosteal collection
- MRI: Shows Bone Marrow changes
- Full blood count: increased WBC, high C reactive protein, raised ESR
Management
- Antibiotics (oxacillin, third generation cephalosporin, vancomycin)
- surgery
- Rest the limb
- Drain or aspirate if abscess is obvious
Adult Osteomyelitis
Pathogenesis: caused by a number of infections
Vertebral osteomyelitis 1
Vertebral osteomyelitis 2
Diabetic foot infection
Osteomyelitis related to metalwork
Symptoms:
- bone and joint dysfunction
- night sweats
- infection of foot ulcer
- normally affects lumbar spine
- Red
- Hot
- Painful
- Pus
- Systemic upset (not in subacute / chronic)
- Nerve compression (spine)
Investigations:
- MRI
- Blood tests
o Hb
o ESR
o WCC
o CRP
- Microbiology very important
- Bone scan
Treatment:
- Laminectomy
- Antibiotics
- Joint immobility – (hard collar)
- Mantoux
- Aspirate
- Culture
- Diabteic control
Chronic osteomyelitis:
o Inappropriately treated acute
osteomyelitis/failure of treatment
of acute osteomyelitis
o Compromised blood supply
o Immunosuppresed
o Diabetic
o HIV/AIDS
Anatomical classification of adult
osteomyelitis 