msk - cortex notes Flashcards
What is an echondroma
Benign bone tumour that is intramedullary adn usually a metaphyseal cartilaginous tumour caused by failure of normal echondral ossification at the growth plate
Can weaken the bone leading to pathological fractures
Can occur in the femur, humerus, tibia and small bones of hand and feet
Can be scraped out
What is a simple bone cyst
A single cavity of benign fluid filled cyst in bone
Usually a growth defect from the physis
Can cause weakness > pathological fracture
Treatment = curettage and grafting
What is an aneurysmal bone cyst
Contains lots of chambers filled with blood or serum
- the different chambers may be seen on x-ray
Due to small arteriovenous malformation
Occur in the metaphyses of long bones , flat bones, and vertebral bodies
This lesion is LOCALLY AGGRESSIVE causing cortical expansion and destruction and so is painful
Treatment = curettage
What is a giant cell bone tumour ?
Can be LOCALLY AGRESSIVE AS WELL AS ANEURYSMAL BONE CYST
Most commonly occur in the knee, distal radius, spine and pelvis
5% can met. To the lung
Treatment = intralesional excision with use of phenol, bone cement or liquid nitrogen
May need joint replacement with very aggressive lesions
*soap bubble appearance on x-ray
Giant cell bone tumour
Which benign bone tumours are locally invasive
Giant cell
Aneurysmal cyst
What is fibrous dysplasia
Benign bone tumour which occurs in adolescence where a genetic mutation results in fibrous tissue lesions and immature bone
Can get defective mineralisation
Treatment = Biphosphonates (reduce pain and risk of pathological fractures)
What is an osteoid osteoma
Benign bone tumours of immature bone surrounded by intense sclerotic halo
Commonly in adolescence and most common site is the proximal femur (long bones)
Intense and constant pain, worse at night
Treatment = NSAIDs, CT guided radio frequency ablation (if doesn’t resolve spontaneously)
Investigation = CT + bone scan to confirm diagnosis
Investigation for osteoid osteoma
CT + bone scan are both needed to confirm diagnosis despite them being seen on x-ray
*brodie’s abscess
Subacute osteomyelitis
*brown tumours
Indicate hyperparathyroidism
Are malignant primary bone tumours common ?
No ! Very rare
But other cancers metastasising to bone is very common
Most common malignant primary bone tumour
Osteosarcoma - seen in younger age groups
60% involving knee bones
Treatment of osteosarcoma
Since they are not radiosensitive
Adjuvant chemotherapy can prolong survival
What is a chondrosarcoma
Malignant cartilage producing primary bone tumour
Less common
Not as aggressive as osteosarcoma
What are fibrosarcoma and malignant fibrous histiocytoma
Fibrous malignant primary bone tumours which tend to occur in abnormal bone ie bone infarct, fibrous dysplasia
What is Ewing’s sarcoma
A malignant tumour of primitive cells in the marrow
2nd most prevalent primary bone tumour
Has the poorest prognosis
Most cases are between the ages of 10-20 years
Staging investigation for primary bone tumours
Bone scan and CT chest
what investigation are helpful to determine local extent of tumours and involvement of muscle, nerve adn vessels
MRI and CT
Treatment of primary bone tumours
Normally surgery to remove the tumour and any surrounding tissue
> limb salvage surgery is better than amputation
Also chemotherapy and radiotherapy
Diagnosis of myeloma
Plasma protein electrophoresis
What are the top5 cancers that metastasise to bone (In order of frequency)
- Breast
- Prostate
- Lung
- Renal cell
- Thyroid adenocarcinoma
Suspected bone cancer investigation
X-ray
What investigation tells you the extent of bony mets. ?
Bone scan
What bone area is considered an ‘at risk’ area for cortical thinning
Subtrochanteric area of the femur
Treatment of fractures / impending fractures ?
Stabilisation via long rods (inrtamedullary nails)
Treatment of joint destruction
Joint replacement
What is the most common benign sot tissue tumour ?
Lipoma
what is a ganglion cyst
Occurs around a synovial joint or tendon sheath
May results as herniation/ out-pouching of weak portion of joint capsule etc
Excision may be required
Can be quite firm and they transilluminate
what is bursitis
A nurse is a small fluid filled sac lined by synovium around a joint which prevents friction (for everything)
Inflamed bursae will usually occur after repeated pressure or trauma which may present as a soft tissue swelling
Excision may be required - there are issues with scarring
Do sebaceous cysts require any treatment ?
Yes - excision and/or biopsy
They are implantation of dermoids
Treatment of abscesses ?
Antibiotics alone is not enough
Need incision + drainage
Risk factors of AVN
Trauma
Idiopathic
Alcoholism (coagulability)
Steroid use - as in long term use of prednisolone (coagulability)
Primary lipidaemia (coagulability)
Weird causes of AVN
Caisson’s disease Aka decompression sickness
Due to nitrogen bubbles forming in the circulation
What happens after AVN
Get osteoarthritis of the area affected
How to treat AVN if the articular surface hasn’t collapsed yet and is in an amenable site ?
‘ Drilling’ with fluoroscopy to decompress the bone - prevent further necrosis and aid healing
Otherwise joint replacement is needed
Disease which put you more at risk of AVN
Thrombophlebitis
Sickle cell disease
Antiphospholipid disease
Primary hyperlipidaemia
(All to do with coagulability)
Osteochondroma
- produces a bony outgrowth on surface of cartilaginous cap
- is the most common
- 1% chance of malignant transformation
what type of bone us this ? (It’s either cancellous or cortical)
It cancellous .
Why ? Cos its at the epiphysis of the bone and it looks like a fine meshwork
Cortical bone makes up the shaft if the bone (diaphysis)
What are A and B
A = epimysium
B = endomysium
A group of muscle fibres are called what ?
Fascicles
What are these lines
Cement lines
What are all these?
what are the cells the arrows are pointing at - and what is the space these cell are located in and also maintain (as they secrete)
Chondrocytes = the cells
Matrix = lacuna (the ECM)
Features that are suggestive of a potential malignant soft tissue neoplasm
Large lesions >5cm
Rapid growth in size
Solid lesion
Illdefined border
Irregular surface
Lymphadenopathy
Systemic upset
What type of muscle is shown here
Skeletal muscle
Peripheral nuclei + striations
Treatment for pathological fracture Of clavicle causing weakness due to simple bone cyst
Should be managed conservatively
*shepherd crook deformity
Fiberous dysplasia
What investigation tells of bone mineral density
DEXA scan
Osteoporosis by DEXA = a score of <2.5
Tool to help evaluate fracture risk
FRAX
5 risk factors for the development of osteoporosis
Lack of sunlight
Female
Increased alcohol intake
Inactivity
Smoking
*bone enlargement, thickened cortices, thickened trabeculae, mixed areas of lyses and sclerosis
Paget’s disease
What are the smallest contractile elements in striated muscle cells
Sarcomere
‘The unit of contraction’ of muscle cell
‘The sarcomere is defined as the region from one Z-disk to the next’
Which cell lays down new lamellar bone
Osteoblasts
Which cells congregate and drill into the bone to form a tunnel
Osteoclasts
DEXA of osteopenia
<1.0 - 2.5
(Whether DEXA of osteoporosis is <2.5, osteopenia is like an intermediate stage)
When do we start losing bone mineral density
Around 30
Why does menopause drive osteoporotic pathway ?
Due to an increase in osteoclastic bone reabsorption
With the loss of protective effects of oestrogen
What are the 2 types of osteoporosis
Type 1 = menopausal
Type 2 = of old age
What fractures are more commonly seen in type 1 osteoporosis
Colles and vertebral insufficiency fractures
What fractures are more commonly seen in type 2 osteoporosis
Femoral neck fractures, vertebral fractures
Investigation of osteoporosis
DEXA
What are 2 things that can increase bone mineral density
A cat purring on top of you
Exercise
Are there any treatments to increase bone mineral density
Nope
Management of osteoporosis = prevent further deterioration ie calcium, vit D supplements, Biphosphonates, desunomab, strontium and zolendronic acid
Treatment of osteoporosis
Vitamin D and calcium supplementation
Biphosphonate
Desonumab
Strontium
Zolendronic acid - once yearly
Can you use intranasal calcitonin for osteoporosis ?
No extra benefit over other treatments and has a an association with increase in cancer
SO NO DO NOT USE
Just for interest
MoA of Biphosphonates
Reduces osteoclastic resorption
MoA desunomab
It’s a monoclonal antibody which reduces osteoclastic activity
MoA strontium
Increases osteoblastic replication and reduces resorption
Difference between osteoporosis and osteomalacia
Osteoporosis = quantitive defect (not enough of)
Osteomalacia = qualitative defect (bone is shit quality bruv)
What is osteomalacia
Abnormal softening of the bone due to deficient mineralisation of osteoid (immature bone) secondary to inadequate amounts of calcium and phosphorus
Is rickets osteomalacia ?
Yes but just in children so has subsequent effects on growing skeleton
Causes of osteomalacia
Malnutrition
Malabsorption
No sunlight exposure (no activation of Vit D)
Hypophosphataemia (re-feeding syndrome/ alcohol abuse)
CKD
Long term anticonvulsant use
*pseudofracture on x-ray
Osteomalacia
Treatment of osteomalacia
Vitamin D therapy with calcium and phosphate supplementation ›
What to remember with hyperPARAthyroidism
Painful moans, renal stones, abdominal groans and psychic overtones
(Overproduction of PTH = hypercalcaemia, = fatigue, depression, myalgia , nausea, thirst, polyuria, renal stones, osteoporosis)
Bone biochemistry for hyperparathyroidism
Serum PTH = ++
Calcium = ++
Phosphate = normal/low
*brown tumours
Hyperparathyroidism fragility fracture
How to treat hypercalcaemia
Emergency
IV fluids
Biphosphonates
Calcitonin
What is renal dystrophy
Describes bone change due to CKD
Reduced phosphate excretion and inactive Vit D results in secondary hyperparathyroidism
What is Pagets
Chronic disorder which results in thickened, brittle misshapen bones
Aka brittle bone disease
Pathophysiogoy of pagets
Increased osteoclastic activity (due to an exaggerated response to vitamin D) leads to osteoblasts trying to catch up and correct excessive bone resorption. The new bone formed fails to remodel sufficiently and so even tho the bone is thick and denser it is brittle and fractures easily
Bones commonly affected in pagets
Pelvis
Femur
Skull
Tibia
Ear ossicles
Hearing problem associated with pagets ?
Conductive deafness due to misshapen ear ossicles
Virus associated with pagets
Paramyxovirus
Bone biochemistry of pagets
Serum alkaline phosphatase is raised
Calcium and phosphorus are usually normal
Treatment of pagets
Biphosphonates or calcitonin if lots of breakdown of bone
Also joint replacement may be necessary
Management of intracapsular displaced hip fractures
Garden III or IV
Either tota hip replacement or hemiarthroplasty ( due to Avascular necrosis of the femoral head )
Management of intracapsular non-displaced hip fracture
This means the blood supply to the femoral head is intact still so can preserve the femoral head
Can be treated therefore with internal fixation (screws) to hold femoral head in place while the bone heals over
Management of extra-capsular intertrochanteric fractures (hip)
Dynamic hip screw
Management of extra-capsular subtrochanteric fracture (hip)
Intramedullary nail
Treatment of mechanical back pain
Analgesia and physio
*pain worse on coughing
Acute disc tear (coughing increases pressure)
Acute disc tear management
Analgesia and physio
Symptoms can take 2-3 months to settle
Commonest nerve roots that can herniate on an acute disc tear
L4 L5 S1 (sciatic nerves)
Damage to what nerve roots cause cauda equina
L1-L5 typically
A laterally placed prolapse between L4-L5 would compress which root ?
L4
A more central prolapse would compress L5
A completely central prolapse would cause cauda equina (C)
D - shows osteophyte formation causing compression
What is spinal stenosis
When multiple nerve roots can be compressed/irritated
Due to combination of spondylosis/bulging discs etc
Features of spinal stenosis
Pain is better walking up hill
Pain is burning
Pedal pulses are preserved
60+ ages and characteristically have pain in the legs when walking (claudication)
Affected sacral nerve roots in cauda equina
S4 and S5
These control defaecation and urination
*saddle anaesthesia
Cauda equina
What investigation is mandatory in cauda equina
PR
Investigation for cauda equina
URGENT MRI
PR exam
Red flags for back pain
- back pain in young <20 years
- new back pain in old people
- constant, severe, worse at night back pain
- systemic upset
Treatment of osteoporotic crush fracture on the vertebral body
Conservation - this fracture is stable
Can sometimes do a balloon vertebroplasty
*slow onset stiffness and pain in the neck which can radiate locally to shoulders and occiput
Cervical spondylosis
*subluxation of Atlanto-axial instability
Is suggestive of what conditions
Downs
RA
This is due to cervical spine instability
Which nerve passes through the carpal tunnel
Median
What is Tinel’s test
Percussion over the radial nerve
Can reproduce carpal tunnel symptoms
Nerve responsible for hip pain referring to groin radiating to knee
Obturator nerve
Muscles responsible for trendelenburg gait
Muscle weakness of gluteus minimus and mediu
