Bone Infection (Acute, Subacute and Chronic Osteomyelitis, Acute Septic Arthritis, Tuberculous Osteomyelitis) Flashcards
How can bone infections spread?
Can occur from metastatic haematogenous spread (carried in the blood), or from local infeciton. They can also occur 2o to vascular insufficiency.
What organisms most commonly affect infants (<1yr)?
- Staph aureus
- Group B streptococci
- E. coli
What organisms commonly affect older children up to age of 4?
- Staph aureus
- Strep pyogenes
- Haemophilus influenzae
- Kingella kingae
What organisms commonly affect Adults?
- Staph aureus
- Coag negative staphylococci - prostheses
- Propionibacterium spp - prostheses
- Streptococcus pyogenes - infectious arthritis
- Mycobacterium tuberculosis
- Pseudomonas aeroginosa - esp. secondary to penetrating foot injuries, IVDAs
What is the pathogenesis of osteomyelitis?
The classical sequence of changes in osteomyelitis is as follows:
- Transient bacteraemia - e.g. Staphylococcus aureus
- Focus to metaphysis of long bone
- Acute inflammation - increased pressure within haversian canals in cortical bone and under periosteum ⇒ periosteum lifts off and interrupts blood supply to underlying bone
- SEQUESTRUM - Caused by necrosis of bone fragments
- INVOLCURM - New reactive bone formation created by the elevated periostium
-
Outcome ⇒ resolution or chronic osteomyelitis
- If untreated, sinuses form, draining pus to the skin surface via cloacae ⇒ Chronic Osteomyelitis
Predisposing conditions to osteomyelitis
- diabetes mellitus
- sickle cell anaemia
- intravenous drug user
- immunosuppression due to either medication or HIV
- alcohol excess
How do bone Abscesses form?
- Acute inflammatory response ⇒ granulation tissue ‘walls off’ sequestrum
- Bacterial proliferation in dead tissue ⇒ pressure & toxins
- Adjacent healthy bone devascularised, further destruction
- Fibrous membrane forms around abscess
- Reactive bone forms ⇒ involucrum ⇒ Bacteria isolated from host defences!
What is the pathophysiology of Chronic osteomyelitis?
- Cavities, poss. sinus(es)
- Cloacae
- Sequestrum + involcrum + sinus
What is the pathophysiology of Septic arthritis?
- Acute synovitis with purulent joint effusion
- Articular cartilage attacked by bacterial toxin and cellular enzyme
- Complete destruction of the articular cartilage
-
Sequelae (1 of the following):
- Complete recovery
- Partial loss of the articular cartilage and subsequent OA
- Fibrous or bony ankylosis
What is the pathophysiology of Tuberculous Arthritis?
- 2 phases
- Early short lived vascular
- Chronic avascular
- Obliterative endarteritis - poor entry of antibiotics
- Less plasminogen activation - less joint destruction
- Primary complex (in the lung or the gut)
- Secondary spread
- Tuberculous granuloma
What are the clinical features of Acute Osteomyelitis in infants?
May be minimal signs, or may be very ill
- FTT
- Possibly drowsy or irritable
- Metaphyseal tenderness + swelling
- Decreased ROM
*Commonest around the knee
What are the clinical feautrues of Acute Osteomyelitis in children?
Vascular bone most affected - long bone metaphyses, esp. distal femur, upper tibia
- Severe pain - May be tender and inlamed
- Reluctant to move - neighbouring joints held flexed
- Not weight bearing
- Fever (swinging pyrexia) + tachycardia
- Systemic features - Malaise fatigue, nausea, vomiting
What are the clinical features of Acute osteomyelitis in an adult?
- Fever
- Localized bone pain - gradual onset over the course of a few days
- Overlying tenderness, warmth and erythema
- Slight effusion in neighbouring joints
What is the presentation of subacute osteomyelitis?
- Long history
- Variable symptoms - pain, limp
- Local swelling/warmth, with Tenderness
- Brodie’s abscess - well defined cavity in cancellous bone
What are the clinical features of Chronic Osteomyelitis?
- Pain
- Fever
- Sequestra - small peice of dead bone separated from live bone
- Sinus suppuration (pathognomic)
-
Risk factors - Diabetic ulcer, Vascular insufficiency
- If bone can be felt on probing ulcer ⇒ CHRONIC OSTEOMYELITIS
What are the clinical features of acute septic arthritis in a neonate?
- Picture of septicaemia
- Irritability
- Resistant to movement
- Ill Child
What are the clinical features of Acute Septic arthritis in a child?
- Acute pain - in single large joint
- Reluctant to move the joint
- Increase temperature and pulse
- Tenderness
What are the clincal features of Acute Septic Arthritis in adults?
- Swelling
- Pain
- Decreased ROM
- Hot, swollen eythematous joint
- Fever and Malaise
What are the clincial featues of Tuberculous Osteomyelitis?
- Insidious onset & general ill health
- Pain - esp. at night
- Swelling
- Weight loss
- Low grade pyrexia
- Decreased ROM
- Ankylosis
- Deformity
What investigations would you do in the context of suspected osteomyelitis?
Clinical Diagnosis, plus
- Bloods - FBC,ESR, CRP, Blood cultures
- Imaging - X-Ray, USS, Isotope Bone Scan, Labelled white cell scan, MRI
- Specific - Biopsy, Tissue swabs, Aspiration
What investigations would you do if you suspected Acute Septic Arthritis?
Bloods
- FBC
- ESR, CRP
- Blood cultures
Imaging
- X ray
- Ultrasound
Other
- Joint Aspiration
What investigations would you perform if you suspected Tuberculous Osteomyelitis?
Clinical diagnosis
Bloods
- FBC
- ESR
Imaging
- X-ray - Soft tissue swelling, periarticular osteopaenia, articular space narrowing
Other
- Mantoux test
- Sputum/urine culture
- Joint aspiration and biopsy
How would you treat someone with Acute osteomyelitis?
Supportive treatment – general care, analgesia
Rest & splintage
Antibiotics
- Flucloxacillin +/- Rifampicin while waiting for cultures
- IV Vancomycin if MRSA
Surgery
- Aspiration of pus for diagnosis & culture
- Abscess drainage
- Debridement
What are the complications of acute osteomyelitis?
- Septicemia
- Pathological fracture
- Septic arthritis
- Altered bone growth
- Chronic osteomyelitis
How would you manage someone with chronic osteomyelitis?
-
Long-term antibiotics
- Local (gentamicin cement/beads, collatamp)
- Systemic (orally/ IV/ home AB)
-
Surgery
- Soft tissue injury
- Deformity correction
- Massive reconstruction
- Amputation
What are the complications of Chronic osteomyelitis?
- Chronically discharging sinus + flare-ups
- Ongoing (metastatic) infection (abscesses)
- Pathological fracture
- Epithelioma
- Growth disturbance + deformities
- Amyloidosis
- Squamous cell carcinoma (0.07%)
How would you treat someone with acute septic arthritis?
- General supportive measures
-
Antibiotics
- Flucloxacillin +/- Rifampicin
- IV Vancomycin (if MRSA)
- Emergency Surgical drainage & lavage where possible
What are the common orgasnisms which cause septic arthritis?
- Staphylococus aureus
- Haemophilus influenzae
- Streptococcus pyogenes
- E. coli
What is are causes of septic arthritis?
Direct invasion
- Penetrating wound (iatrogenic? – joint injection)
- Intra-articular injury
- Arthroscopy
Eruption of bone abscess - see picture
Haematogenous
Infected joint replacement
- Now most common cause of septic arthritis in adult
- Staph. aureus still most common organism
What is the differential diagnosis for someone who is presenting with symptoms of septic arthritis?
- Acute osteomyelitis
- Trauma
- Irritable joint
- Haemophilia
- Rheumatic fever
- Gout
- Gaucher’s disease
What is the differential diagnosis for someone who is presenting with symptoms of acute osteomyelitis?
- Soft tissue infection - Cellulitis, Erysipelas, Necrotising fasciitis, Gas gangrene, Toxic shock syndrome
- Acute septic arthritis
- Trauma
- Acute inflammatory arthritis
- Transient synovitis (“irritable hip”)
- Rare - sickle cell crisis, Gaucher’s disease, rheumatic fever, haemophilia
What is the treatment for Tuberculous Bone Infection?
-
6 months
- Rifampicin
- Isoniazid
-
First 2 months
- Ethambutol
- Pyrazinamide
What is the following?
Sinus caused by chronic osteomyelitis
What are the characteristics of an infected joint on examination?
Hot, swollen, tender, erythematous joint with decreased ROM. MAy or may not have a fever
What antibiotics might you use to empirically treat septic arthritis?
4-6 weeks
- IV Fluclox +/- rifampicin, then switch to oral
- Vancomycin if MRSA or penicillin allergic
Whats illiospoas abscess?
Collection of pus in iliopsoas compartment (iliopsoas and iliacus)
Causes of illiopsoas abscess?
-
Primary
- Haematogenous spread of bacteria
- Staphylococcus aureus: most common
-
Secondary
- Crohn’s (commonest cause in this category)
- Diverticulitis, Colorectal cancer
- UTI, GU cancers
- Vertebral osteomyelitis
- Femoral catheter, lithotripsy
- Endocarditis
Clinical features of illiopsoas abscess
- Fever
- Back/flank pain
- Limp
- Weight loss
Test for illiopsoas inflammtion
Place hand proximal to the patient’s ipsilateral knee and ask patient to lift thigh against your hand. This will cause pain due to contraction of the psoas muscle.
Lie the patient on the normal side and hyperextend the affected hip. In inflammation this should elicit pain as the psoas muscle is stretched.
Gold standard investigation illiopsoas abscess
CT is gold standard
Management of illiopsoas abscess
- Antibiotics
- Percutaneous drainage
- Surgery is indicated if:
- Failure of percutaneous drainage
- Presence of an another intra-abdominal pathology which requires surgery
