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 #