Bone and Joint Infection Osteomyelitis/Septic Arthritis Flashcards
What is the name of bone infection?
Osteomyelitis
What is the difference on x-ray between acute and chronic osteomyelitis?
Acute- no bone damage seen on x-ray
Chronic- bone damage seen on x-ray
Septic arthritis?
Infection of the joint
In which age group in acute osteomyelitis more common in?
Children
Boys > girls
->often in more deprived areas
Acute osteomyelitis can occur in adults, usually in those with underlying causes such as?
Usually some type of immunocompromise
e.g. diabetes, rheumatoid arthritis, steroids, sickle cell disease
What is usually the source of infection in acute osteomyelitis?
Usually haematogenous spread e.g. child scraping knee and entering through skin
Okay lets break this down a bit
In infants, what is the most common cause of infection which leads to acute osteomyelitis?
Infected umbilical cord
Okay lets break this down a bit
In children, what is the most common cause of infection which leads to acute osteomyelitis?
Boils, tonsillitis, skin abrasions
Okay lets break this down a bit
In adults, what is the most common cause of infection which leads to acute osteomyelitis?
UTI, arterial line, chest infection, gall bladder infection
What is the most common causative microorganism of acute osteomyelitis?
Staph. Aureus
What is the most common causative microorganism of acute osteomyelitis in infants <1yr?
Staph Aureus-most common
Group B streptococci- common in childbirth etc
E.Coli
What is the most common causative microorganism of acute osteomyelitis in older children?
Staph Aureus- most common
Strep pyogenes
Haemophilus influenzae
What is the most common causative microorganism of acute osteomyelitis in adults?
Staph Aureus- most common
Pseudomonas aeruginosa- often of foot
What would be the causative microorganism of patients with acute osteomyelitis and diabetic foot and pressure sores?
Mixed infection including anaerobes
Which microorganisms tend to cause vertebral osteomyelitis?
S.Aureus
TB
Which microorganisms tend to cause osteomyelitis related to sickle cell disease?
Salmonella
Which bones does acute osteomyelitis tend to affect more?
Long bones in the metaphysis- distal femur, proximal tibia/humerus
Which joints does acute osteomyelitis tend to affect more?
Joints with intra-articular metaphysis e.g. hip and elbow
How can a patient get septicaemia from osteomyelitis?
Build up of pus within bone- usually after trauma- which can burst out into the joint and cause infection of blood or septic arthritis
What is the treatment prognosis like for acute osteomyelitis?
As acute, can treat aggressively before bone destruction
Sequestrum?
Necrosis of bone, no blood supply
Involucrum?
Formation of new bone around the dead bone
No matter how much antibiotic is given, it cannot get into the sequestrum, why is this?
It’s dead bone with no blood supply
The extra involucrum around it isolates the dead bone even more
->these factors are seen in chronic osteomyelitis
What are the clinical features of acute osteomyelitis in infants?
Redness and infection around umbilicus
Failure to thrive
Not feeding
Pseudo-paralysis
What are the clinical features of acute osteomyelitis in children?
Severe pain
Reluctant to move
Swinging pyrexia
Malaise; vomiting, nausea
->classical presentation is injury a few days ago but then fine shortly after, sore the next day, fever the day after, and progresses like that
What are the clinical features of acute osteomyelitis in adults?
Backache- unremitting and at rest
History of UTI or urological procedure
->primary osteomyelitis most commonly seen in thoracolumbar spine hence backache
Who is secondary osteomyelitis more common in?
Adults
Often after an open fracture or surgery
Diagnosis of acute osteomyelitis and investigations?
History and clinical examination
Bloods: FBC, WBC, ESR, CRP
Blood cultures- repeated
U&E indicative of illness and dehydration
Bone biopsy occasionally to get organism and confirm diagnosis but not the common way of doing this
Bone scans
->some of these flashcards are a bit wordy but really recommend rewatching this lecture, really good
What are ESR and CRP markers of?
Markers of inflammation
X-ray can be done for acute osteomyelitis but what needs to be bared in mind?
Normal in first 10-14 days after injury
What is seen in x-ray in acute osteomyelitis after 10-20 days?
Early periosteal changes and medullary changes
What can be shown by x-rays later into osteomyelitis, when it is potentially reaching the chronic phases?
Sequestrum- bone necrosis
Involucrum - new bone
If giving a child an MRI, what may they need?
If less than six, a general anaesthetic so they stay still!!
What is done for a microbiological diagnosis of acute osteomyelitis?
Blood cultures
Potential bone biopsy if not sure of primary source of culture
Treatment of acute osteomyelitis?
Supportive- pain and hydration
Rest and splintage of limb
Antibiotics
->tends to be overtreated just to really reduce risks of chronic osteomyelitis which is a lifelong condition
Acute osteomyelitis is very rarely treated using surgery but what are some of the surgical indications?
If required to collect aspiration of pus for diagnosis and culture
For abscess draining if fever not responding to treatment
Debridement of dead or infected tissue
Complications of acute osteomyelitis?
Metastatic infection
Pathological fracture
Septic arthritis
Septicaemia, death
Altered bone growth
Chronic osteomyelitis
Chronic osteomyelitis is a lot rarer, especially in children, but can follow acute osteomyelitis.
However, why else may it occur?
Following operation
Following open fracture
Immunosuppressed, diabetics, drug abusers
Treatment of chronic osteomyelitis?
Long term antibiotics
Eradication of infected bone- often massive surgery
Amputation?
Complications of chronic osteomyelitis?
Chronically discharging sinus and flare-ups
Ongoing metastatic infection
Pathological fracture
Marjolin’s ulcer- very rare but a type of squamous cell carcinoma due to chronic discharge of bone and irritation of local tissues
What are some of the routes of infection of septic arthritis?
Haematogenous
Eruption of bone abscess
Direct invasion e.g. penetrating wounds
Most common causative microorganisms of septic arthritis?
Staph.Aureus
Haemophilus influenzae
Streptococcus pyogenes
E.Coli
Pathology behind septic arthritis?
Acute synovitis with purulent joint effusion
Articular cartilage attacked by toxins leading to destruction of the cartilage
Outcomes of acute septic arthritis?
Complete recovery
or
Partial loss of articular cartilage
or
Fibrous or bony ankylosis
How does septic arthritis present in neonates?
Irritability
Resistant of joint movement
Septicaemia
How does septic arthritis present in children?
Acute pain in single large joint
Tachycardia
Pyrexia
Tenderness
What is the difference between a child with a skin infection and a child with acute septic arthritis?
Acute septic arthritis has such severe pain that child will not let you touch the joint
Treatment of acute septic arthritis?
General supportive measures
Urgent surgical drainage
Antibiotics
Infected joint replacements
TB can affect bones and joins and is known as being the ‘great mimic’.
Where can TB impact?
Extra-articular
Intra-articular
Vertebral bodies- multiple lesions in 1/3 of patients
Clinical features of TB?
Insidious onset and general ill health
Contact with TB
Pain, esp at night
Sweating
Weight loss
Joint swelling
Low grade pyrexia
Progressive deformity
Where is commonly the primary TB infection found in the body?
Lung or gut
->this then spreads e.g. vertebral joints
Which investigations are used to diagnose TB?
Bloods; FBC, ESR
Sputum/urine culture
X-rays
Joint aspiration and biopsy
Treatment of TB?
Mostly antibiotics, combination of them
