Musculoskeletal System Flashcards
When answering the questions, what should be considered for each pathology?
For each pathology: -
- Patient presentation
- Potential pathway
- Differential diagnosis (DD)
- Appropriate imaging/diagnostics
What imaging modality is best used for bones and complex fractures?
CT
MRI is the best imaging modality for?
Joints and soft tissue structures
What is US used for in relation to MSK pathology?
Studies of joint
Fluid filled structures
Superficial structures
Some trauma cases (operator dependent - long wait)
What is RNI used for?
Fracture/ neoplasm detection
What is DEXA and Arthrography used for?
DEXA - Bone density
Arthrography - Assessment of joints
Why is CT most commonly used?
- Widely available
- Quick, easy and safe in trauma/emergency situation
- MPR and 3D recon in complex fractures –(full assessment/ongoing pathway planning)
- The spinal canal is well visualised and bone fragments impinging on the spinal cord can be seen
- Sensitive for cortical destruction and soft tissues (good resolution)
- Staging – distant
Why is MRI used?
- Can diagnose bone bruising (early sign of trauma), and avascular necrosis (later)
- Useful in the carpus, especially occult fractures of the scaphoid which are often missed on conventional images)
- MRI provides superior ST definition & is invaluable for diagnosing injuries to joints/soft tissues, e.g. ligament laxity/tears, meniscal tears, cartilage and bone injuries
- Accurate definition of tumor extent within marrow and into soft tissues
- Very sensitive in the arthritides
- Both sensitive and specific in the diagnosis of occult fractures
What are the negatives of using MRI?
- Time consuming and not always readily available
- Must consider magnet safety (patients with ferrous foreign objects etc.) and patient acceptability (claustrophobia)
- Limited sensitivity in diagnosis of fractures at the time of the injury (high false positive rate)
What is MR Arthrography used for?
Used for diagnosis of internal shoulder joint derangements
Assess the joint capsule in shoulders
For looking at inside the shoulder joint to assess for injury/wear and tear
Can diagnose tendon tears, ligament detachments and cartilage damage
What contrast agent is used in MR Arthrography?
Gadolinium and Iodinated contrast
What are the negatives with using contrast for MR Arthrography?
- Slightly invasive technique as contrast is injected directly into the joint
- Joint is painful afterwards plus possible complication of infection in the joint
Why is US useful in MSK imaging?
No radiation dose
Fast, cheap and readily available
Assessing neurovascular structures (soft tissues, fluid filled & superficial structures)
Good ST assessment & useful for image guided biopsy
What pathologies on the knee is US widely used for?
- Patellar tendonitis/apexitis – “jumper’s knee”
- Medial meniscus tears
- Quadriceps insertion tendinopathy with tendinosis, and calcifications
- Joint effusion/cysts
How is Patellar tendonitis/apexitis – “jumper’s knee” visualised on US?
The patellar tendon is inflamed and thickened
Intrasubstance high signal intensity
Partial tearing of the proximal patellar tendon
What is tendinosis?
Tendinosis is the non-inflammatory degeneration of a tendon. This degeneration can include changes to the structure or composition of the tendon.
These changes often result from repetitive strain-injuries to a tendon without adequate time to heal.
What are the signs & symptoms of Achilles Tendinopathy?
- Aching (occasionally sharp) pain in the heel.
- Pain isaggravated by activity or pressure to the area.
- Stiffness in the tendon, which may occur in the morning or after a period of prolonged sitting.
- Tenderness, swelling, and crepitus along the tendon.
Why is RNI used for MSK?
- High sensitivity for bony pathology and trauma, identifies cellular function
- Can be combined PET/SPECT
- Used in screening for metastatic bone disease
- Confirming occult fractures and identifying areas of bone infection/osteomyelitis
- Investigating metabolic bone disease, e.g. Paget’s
What are the negatives of using RNI?
- Less readily available/longer examinations
- Ionising radiation & aftercare requirements
- Lack of specificity in disease characterisation, e.g. # scaphoid v. OA CMC joint thumb
What is DEXA used for in MSK imaging?
To assess bone density and also risk osteoporosis
What are the indications required for a DEXA scan?
Fracture: minor fall or injury
Early menopause
Ovaries removed (before 45)
Hasn’t had a HRT
Post-menopausal who smokes and drinks heavily
Family history of hip fractures
BMI < 21
Condition such as RA that leads to low bone density (male and female)
Large gaps between periods (> year)
Oral glucocorticoids for > 3 months (male and female)
Why is Arthrography used?
Examines the inside of a joint to assess an injury or symptom (shoulder, knee, wrist, ankle)
The most sensitive non-invasive examination for the evaluation of the joint capsule in shoulders
How is Arthrography conducted?
The contrast medium is injected into the joint capsule, which outlines the soft tissue structures (ligaments and cartilage)
Done under fluoroscopy to guide the placement of the needle for the contrast to be administered
It can be done using CT, US or MRI
What are the radiological features of tumors?
Solitary or multiple
Lytic or sclerotic
Type of bone (long bone, vertebra)
Where in the bone is the lesion (cortex, medulla, shaft)?
well-defined margin?
Cortical destruction?
Bony reaction?
Central calcification?
Soft tissue involvement?
What are solitary bone cysts?
- Asymptomatic unless fractured, then pain and limited ROM
- Solitary lytic metaphyseal lesion
well-defined (possibly thin sclerotic) margin; narrow zone of transition - ‘Fallen fragment sign’ when fractured
Healing fracture results in disappearance of the cyst
What is Osteochondroma?
–> Most common benign bone tumors: distal femur, proximal tibia, iliac crest (<age 20; M:F = 3:1)
–> Overgrowth of cartilage at margin of physis (grow away from it); ossification then produces a bony protuberance with a cartilage cap
–> Stop growing at skeletal maturity
often incidental finding but can produce a mass
–> Usually asymptomatic, they vary in size
Visible on x-ray/CT, and cartilage cap on US, MRI is the best
What is multiple Myeloma?
Cancer of the plasma (white blood cells)
M:F = 2:1
Multiple sites - vertebra, ribs, skull, shoulder, pelvis, long bones
What is the clinical presentation of multiple myeloma?
Presents with bone pain and associated fatigue +/- weight loss, anaemia
What are the radiological signs of multiple myeloma?
Early onset shows widespread osteoporosis and prominent trabeculae (spine ‘punched out’ lesions, ‘moth eaten’ pattern)
What imaging modality and treatment are required for multiple myeloma?
Skeletal survey first; MRI and PET
Chemotherapy; palliative radiography for painful lesions or lesions likely to develop pathological #
What is Osteosarcoma?
The most common primary malignant bone tumour in older children (rare <5)
May be seen in adults as a result of previous radiotherapy or Paget’s disease
It arises in medullary canal and grows out and through the periosteum into surrounding ST’s
Long bone metaphyses, but will cross the physis before plate closure (>75% cases)
What is the clinical presentation of osteosarcoma?
Pain - constant, worse at night and gradually increasing in severity
A palpable lump may be present later; +/- pain on examination
What is the imaging modality and radiolographic appearance of osteosarcoma?
CT/MRI to assess tumour extent; RNI bone scan for further lesions; CXR/CT chest for mets
Radiologically: large bone lesion when detected; mixed density; ill-defined margins; bone destruction and cortical disruption; often associated aggressive periosteal reaction
What is Ewing Sarcoma?
2nd most common malignant bone tumour in children
M>F; 5-30 yrs; rare >30
Arise in medullary cavity of long bones (pelvis, femur)
What is the clinical presentation of ewing sarcoma?
Localised pain and swelling; also fever, weight loss and anaemia
What is the radiographic appearance of Ewing sarcoma?
Ill-defined
Lytic
Destructive lesion; associated soft tissue mass/infiltration; and periosteal reaction
Mets may be present in 30% of cases at initial involvement
What imaging modalities are used for Ewing sarcoma and why?
MRI for full evaluation (ST involvement; also staging)
RNI bone scan for mets
CT for bone destruction/extra-osseous involvement
Where are bony metastases common?
In vertebrae
Pelvis
Proximal femur
Proximal humerus
Lung
Kidney
Prostate (male)
Breast (female)Wh
What are the clinical presentations of bony mets?
It depends on the primary but rest pain and night pain are ‘red flag’ symptoms
Bony pain, systemic upset and pathological #
Sudden onset pain in elderly
Incidental finding on staging
What are the radiological aprearence of the bony mets?
Lytic: kidney, lung, thyroid, breast
Sclerotic: prostate, breast, stomach
Bone destruction; wide zone of transition
What imaging modality is used to define bony mets distribution?
RNI bone scan
Where does fibrous cortical defect/non-ossifying fibroma occur in?
Femur and tibia
What is the radiological appearance of fibrous cortical defect/non-ossifying fibroma?
Lucent lesion with well-defined sclerotic margin
May be loculated
Arises from cortex
Slightly expansile
What is the potential patient pathway for arthritis?
GP
Often, incidental findings on images
Specialist referral (rheumatology clinic)
What is Osteoarthritis?
Degenerative joint disorder
Progressive loss of articular cartilage and new bone formation
Can be secondary (trauma to the joint)
In what part of the body is osteoarthritis more common?
In weight bearing joints -
- hip
- knee
- spine (‘spondylosis’)
- IP joints (females)
What is the clinical presentation of osteoarthritis?
Pain (morning or after rest)
Aggravated by exertion (adjacent joint)
Stiffness after inactivity (constant with disease progression)
Soft tissue swelling
What are the radiological apprearance of osteoarthritis?
Bone density preserved
Joint space narrowing
Subchondral sclerosis
Marginal osteophytes
Subarticular cysts
What is the best imaging modality for osteoarthritis?
MRI to identify cartilage loss, effusions and cysts
What is rheumatoid arthritis?
Chronic inflammatory disease affecting synovium and articular surface
M=F (F>M in earlier years)
Articular erosion and destruction results in joint deformity and disability
Late joint destruction and deformity
What are the clinical presentation of rheumatoid arthritis?
Fever
Hot joints - Swollen and painful
Effusion/bursitis
Malaise
Weight loss
Weakness
What other body systems are affected by rheumatoid arthritis?
Chest - pulmonary interstitial fibrosis aka ‘rheumatoid lung’
What are the early radiological signs of rheumatoid arthritis?
ST swelling
Local osteopaenia
Marginal and central bone erosions
Joint space widening
What are the late radiological signs of rheumatoid arthritis?
Loss of joint space
Marked destructive changes
Subluxations
Fragmentation
Fractures and
Ankylosis (fusion)
What imaging modality is best used to visualise rheumatoid arthritis?
MRI and US
What is MRI used for RA?
Assessment of peripheral joints for active inflammation in the form of joint effusions, synovitis
Assessment of structural lesions e.g. articular cartilage damage, cortical bone erosions and tendons tears
Assessment of inflammatory changes and post-inflammatory complications in the spine, i.e. assessment of inflammatory activity
Why is US used in RA?
High availability
low cost
high patient acceptance compared to MRI
Assessment of peripheral joints for active inflammation in the form of effusion, synovitis, etc.
Assessment of structural lesions such as tendons tears (cortical bone erosions and articular cartilage damage can be seen to some extent)
Dynamic examination of peripheral joints, useful in the assessment of inflammatory changes
Measurements of inflammation (intensity of vascularization, thickness of synovium)
What is metabolic bone disease?
Disorders of bone strength, usually caused by abnormalities of minerals (e.g. calcium, phosphorus), vitamin D, bone mass or bone structure, but can also be due to e.g. prolonged steroid use
What does metabolic bone disease include?
Osteoporosis
Paget’s disease
Patients who suffer bone pain due to metabolic disease are more predisposed to what?
Fractures including vertebral compression, which leads to loss of height
What is osteoporosis?
Systemic skeletal disease characterised by low bone mass and deterioration of bone tissue
Systemic skeletal disease characterised by low bone mass and deterioration of bone tissue
Vertebral fractures often asymptomatic and discovered incidentally; kyphosis and loss of height can result from vertebral compression fractures
Who is most affected by osteoporosis?
Post-menopausal women
What is the prevalence of osteoporosis?
Increases with age
What is the imaging modality for osteoporosis?
DEXA is investigation of choice for diagnosis
What is the aetiology for paget’s disease?
Unknown aetiology; causes abnormal remodelling of bone – thickened, disorganised fragile trabeculae result
What is the radiological appearance of paget’s disease?
Radiologically: “cotton wool bones”; thickened cortices, coarse trabeculae; cyst-like areas during early lytic phase
What is the prognosis of pagets disease?
Poor - Potential for sarcomatous change
What part of the body is affected by paget’s disease?
pelvis
lumbar and thoracic vertebrae, proximal femur, skull and tibia
What is acute osteomyelitis?
Pathological sequence is inflammation, suppuration, necrosis, new bone formation, resolution
How does acute osteomyelitis spread?
Spread via blood supply (haematogenous) or direct implantation from trauma
Who are affected by acute osteomyelitis?
Majority children
Immunocompromised adults (diabetes, drugs, disease)
Adults (spine or lower extremities in diabetics)
What is the patient presentation of acute osteomyelitis?
Feverish and general malaise
Severe pain
Later – local erythema, oedema, warmth
Beware adults with new onset back pain with associated systemic upset
Lymphadenopathy present but not specific
Infants may present as non-specific failure to thrive
Symptoms may also be mild in elderly and immuno-suppressed
What imaging modalities are used for acute osteomyelitis?
Plain imaging initially likely to be normal
Look for displacement of fat planes – due to soft tissue swelling or accumulation of fluid
Visible lucency ~5-7 days
Bony necrosis and periosteal reaction ~10-14 days
MRI useful in early stages – bone marrow changes
NM bone scans useful
What are the future trends and treatments for spinal stenosis?
Neurosurgical treatment
Physical therapy
Medicine (muscle relaxant)
Steroid Injection
What are the MSK interventions?
Facet joint injection (fluro/ CT)
Nerve root block (Fluoro)
Radio-frequency ablation (Fluoro, CT, MRI)
Thermal ablation (CT, MRI, or US)
Discography
Percutaneous vertebroplasty/balloon kyphoplasty
What is the future trend for MSK pathologies?
Digital Tomosynthesis:
An imaging technique that uses standard X-ray equipment with digital flat panel detectors to create tomographic images from very low-dose projections obtained at different angles
Why is digital tomosynthesis used?
Lower dose to CT and standard radiography
It is superior to conventional radiography when there are bone superimpositions or when metal structures hide regions of interest
The high resolution and its ability to perform examinations in weight-bearing positions are some of the main advantages of this technique
