Orthopaedics I Flashcards
(34 cards)
Clinical features of acute [3] and chronic osteomyelitis [3] ?
Acute osteomyelitis:
- Pain is the most common symptom
- Warm and erythema
- Systemic symptoms
Chronic osteomyelitis:
- Tends to present only with local symptoms such as swelling, erythema and pain
- Systemic symptoms such as fever are often ABSENT
- Often secondary to DM vascular injury - diabetics with ulcers >2cm2 are very likely to have osteomyelitis, even if no bone is visible
- A draining sinus tract may be seen - this is pathognomonic of osteomyelitis
-
In patients with a history of intravenous drug use, what organism is the most common cause for osteomyelitis?
Salmonella spp.
S. aureus
P. aeruginosa
E. coli
In patients with a history of intravenous drug use, what organism is the most common cause for osteomyelitis?
Salmonella spp.
S. aureus
P. aeruginosa
E. coli
Investigations for osteomyeltis? [+]
Serology:
- Acute = raised WCC / CRP
- Chronic = often has normal WCC
- Blood cultures are positive in around half of cases
X-ray:
- Acute = first two weeks of infection may show normal
- Soft tissue swelling, osteopaenia (bone thinning), bone destruction, periosteal reaction (changes to the surface of the bone), endosteal scalloping and new bone apposition
MRI:
- Best imaging for dx
- Sequestrum: Refers to a dead piece of devitalised bone that has been separated (i.e. sequestered) due to necrosis from the surrounding bone.
- Involucrum: New growth of periosteal bone around a sequestrum.
- Cloaca: An opening in an involuvcrum that allows the internal necrotic bone and pus to discharge out.
Label A-C
Sequestrum: Refers to a dead piece of devitalised bone that has been separated (i.e. sequestered) due to necrosis from the surrounding bone.
Involucrum: New growth of periosteal bone around a sequestrum.
Cloaca: An opening in an involuvcrum that allows the internal necrotic bone and pus to discharge out.
Describe the difference between sequestrum vs involucrum? [1]
A sequestrum is the necrotic bone which has become walled off from its blood supply and can present as a nidus for chronic osteomyelitis.
An involucrum is a layer of new bone growth outside existing bone seen in osteomyelitis.
Describe the treatment for osteomyelitis [3]
Antibiotics +/- surgical debridement forms the mainstay of management.
Abx:
- Should be held until bone cultures are completed
- Guided by microbiology
- BNF: flucloxacillin for 6 weeks; possibly with rifampicin or fusidic acid added for the first 2 weeks
- Chronic osteomyelitis usually requires 3 months or more of antibiotics.
- Clindamycin in penicillin allergy
- Vancomycin or teicoplanin when treating MRSA
Surgery:
- More common in non-haem. spread
- infected necrotic bone must be removed
- Irrigation & debridement - sequestrum must be eliminated from the body, or infection is likely to recur; replace dead bone and scar tissue with vascularized tissue
Describe the different causes of septic arthritis
When septic arthritis is caused by haematogenous spread it may be a result of:
Bacterial migration from a distant site
* Abscesses and wounds
* Septicaemia
Disseminated infection
* Gonorrhoea
OR
When septic arthritis is caused by direct inoculation it may be a result of:
Iatrogenic procedures
* Joint injections (e.g. steroid injections)
* Joint arthrocentesis
* Athroscopy
Traumatic injuries
* Infected wounds around the joint
* Penetrating injuries from foreign objects
Describe investigations for septic arthritis? [2]
Joint aspiration is key and should be obtained prior to antibiotics (whenever possible):
- Also decompresses joint space
- synovial fluid appearance: often yellow/green and turbid on aspiration compared to uninfected fluid which is clear and usually colourless.
- Cultures of synovial fluid in cases of gonococcal septic arthritis yield positive results in only 25% of cases.
- Synovial fluid WCC: is often raised with neutrophil predominance. WBC: >50 000 cells/mm3 with Neutrophils: >75 %
The Kocher criteria for the diagnosis of septic arthritis is [4]
The Kocher criteria for the diagnosis of septic arthritis:
* fever >38.5 degrees C
* non-weight bearing
* raised ESR
* raised WCC
Describe the management plan for septic arthritis
First: rule out sepsis
Empirical IV antibiotics should be given until the sensitivities are known. Often following are given:
* Flucloxacillin (often first-line)
* Clindamycin (penicillin allergy)
* Vancomycin (if MRSA is suspected)
* Ceftriaxone if gonorrhoea
Antibiotics are typically continued IV for 2 weeks before switching to PO if the patient is improving.
A patient presents with ?osteomyelitis. An MRI is performed.
What does the arrow point at? [1]
involucrum: formation of new bone around an area of bony necrosis
A patient presents with ?osteomyelitis. An MRI is performed.
What does the arrow point at? [1]
sequestrum: devitalized bone that serves as a nidus for infection
Describe the positions of a sequestrum vs a involucrum [2]
A sequestrum is the necrotic bone which has become walled off from its blood supply and can present as a nidus for chronic osteomyelitis.
An involucrum is a layer of new bone growth outside existing bone seen in osteomyelitis.
State causes of secondary osteoporosis [+]
Endocrine:
- DM
- Cushings
- Hyperparathyroidism
- Hyperthyroidism
- Low testosterone
Malabsorptive
- IBD
- Coeliac
COPD
CKD
Chronic liver disease
How would you differentiate osteoporosis and osteomalacia?
- presentation [2]
- investigations [1]
osteomalacia may cause generalised bone pain, tenderness and myopathy
- low Ca and PO4 serum; high ALP and PTH
Describe the treatment algorithm for osteoporosis [4]
First line: Bisphosphonates
- oral alendronate or risedronate weekly oral
- zoledronic acid - yearly infusion
- MOA: interfering with the way osteoclasts attach to bone, reducing their activity and the reabsorption of bone.
Second line: Denosumab:
- monoclonal antibody agaisnt RANK ligand, inhibits osteoclasts
- SC every 6 months
- can be used for osteoporosis in post-menopausal women or OP In men
- can be used for patients on steroids
Raloxifene
- Raloxifene is approved for the treatment and prevention of osteoporosis in postmenopausal women
- selective oestrogen receptor modulator (SERM)
HRT: unopposed oestrogen or O&P
- Prevention of fracture in women at high risk. It is normally reserved for use in younger women as the side effect profile is better.
Clinical scenarios
- if a patient is deemed high-risk based on a QFracture or FRAX score they should have a DEXA scan to assess bone mineral density (BMD): if T-score of - 2.5 SD or below start bisphosphinates
- A postmenopausal woman, or a man age ≥50 has a symptomatic osteoporotic vertebral fracture: above
start treatment straight away - oral bisphosphonates are used first-line e.g. alendronate or risedronate
- following a fragility fracture in women ≥ 75 years, a DEXA scan is not necessary to diagnose osteoporosis and hence commence a bisphosphonate
Which groups are bisphosphinates CI in? [3]
Severe renal impairment (renally excreted)
Hypocalcaemia
Upper GI disorders
Smokers and dental disease should be cautioned because of jaw necrosis risk
In which patient groups is raloxifene CI In? [1]
history of venous thromboembolism or if a patient has prolonged immobilisation due to risk of VTE
Name three side effects of raloxifene [3]
Side effects include hot flushes, vaginal dryness and leg cramps.
NB: Raloxifene is a selective oestrogen receptor modulato
Name two side effects of denosumab [2]
In which patient populations is it CI In? [3]
Side effects include cellulitis and hypocalcaemia
CI in hypocalcaemia and hypersensitivity and avoided in pregnancy.
heparin
Name the clinical presentation of the hand signs of OA [5]
Heberden’s nodes (in the DIP joints)
Bouchard’s nodes (in the PIP joints)
Squaring at the base of the thumb (CMC joint)
Weak grip
Reduced range of motion
NICE CG 226: Osteoarthritis in over 16s: diagnosis and management (2022) advise a clinical diagnosis (without imaging) can be made when a patient: [3]
- Is 45 or over and
- Has activity-related joint pain and
- Has either no morning joint-related stiffness or morning stiffness that lasts no longer than 30 minutes.
