Robert R' Bleakney

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Essentials of Musculoskeletal Radiology

• Robert R. Bleakney
• Mount Sinai Hospital
• University Health Network
• University of Toronto

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• Modalities of MSK
• Approach to fractures
• Approach to bony lesions
• Approach to arthritis

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Modalities

• plain film
• computed tomography
• ultrasound
• nuclear medicine
• interventional
• magnetic resonance imaging

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Plain Film

• mainstay of bone and joint imaging, particularly
  in trauma
• advantages
• fast
• inexpensive
• readily available
• good for assessing bones and joints

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Plain Film

• mainstay of bone and joint imaging, particularly
  in trauma
• disadvantages
• uses ionising radiation (x rays)
• limited information regarding soft tissues

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Computed Tomography (CT)

• x ray tube rotated around the patient
• cross sectional imaging capability
• reformatting in other planes and 3D
• best for bony cortex and calcification
• good at evaluation of comminuted fractures to
  complex structures
• pelvis
• calcaneus
• wrist

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calcaneal fracture
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coronal and sagittal reformatting
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Computed Tomography (CT)

• disadvantages
• radiation dose to patient
• metal artefact
• poor soft tissue characterization

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CT MRI
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Ultrasound

• relatively inexpensive
• sound waves reflecting from soft tissue
  interfaces
• no ionizing radiation
• MSK applications
• infants for DDH
• tendon injuries especially rotator cuff
• soft tissue masses
• US guided biopsy

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normal supraspinatus tendon longitudinal trans
verse
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normal supraspinatus tendon longitudinal trans
verse
full thickness supraspinatus tear
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Nuclear Medicine

• entire skeleton at once
• bone scan is an indicator of bone turn over
• very sensitive, not specific
• fracture
• tumour
• arthritis
• infection
• metabolic bone disease

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Nuclear Medicine

• Non-specific uptake xiphoid process region of
  the sternum. Correlation with clinical
  examination suggested.
• Unless there has been trauma to these sites I
  cannot exclude metastatic disease and further
  radiologic correlation is recommended.
• This likely represents a normal variant,
  however, correlation with x-ray is recommended to
  rule out loosening or other pathology.
• Clinical correlation and further investigation
  with a left shoulder radiograph is recommended.
• Suspected degenerative change midcervical spine,
  radiograph would be confirmatory.
• Possible traumatic injury to the
  sternoclavicular joints bilaterally. Radiographic
  correlation is recommended.
• Mild focal activity within the left acetabulum
  anteriorly which is non-specific and could be
  related to either degenerative changes or a
  metastatic deposit.

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Nuclear Medicine

• Non-specific uptake xiphoid process region of
  the sternum. Correlation with clinical
  examination suggested.
• Unless there has been trauma to these sites I
  cannot exclude metastatic disease and further
  radiologic correlation is recommended.
• This likely represents a normal variant,
  however, correlation with x-ray is recommended to
  rule out loosening or other pathology.
• Clinical correlation and further investigation
  with a left shoulder radiograph is recommended.
• Suspected degenerative change midcervical spine,
  radiograph would be confirmatory.
• Possible traumatic injury to the
  sternoclavicular joints bilaterally. Radiographic
  correlation is recommended.
• Mild focal activity within the left acetabulum
  anteriorly which is non-specific and could be
  related to either degenerative changes or a
  metastatic deposit.

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bone scan normal multiple metastases
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normal plain film bone scan multiple bony
metastases
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Interventional

• arthrography
• joint injections and aspiration
• biopsy
• ultrasound guided
• CT guided
• spinal interventional
• nerve root blocks
• facet joint injections
• discograms

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Magnetic Resonance Imaging (MRI)
Press Release The 2003 Nobel Prize in Physiology
or Medicine 6 October 2003 The Nobel Assembly at
Karolinska Institutet has today decided to award
The Nobel Prize in Physiology or Medicine for
2003jointly to Paul C Lauterbur and Peter
Mansfield for their discoveries concerning
magnetic resonance imaging"
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Magnetic Resonance Imaging (MRI)

• patient in a strong magnetic field
• multiplanar imaging
• excellent soft tissue contrast
• ideally suited for MSK

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coronal sagittal axial
soft tissue contrast and multiplanar imaging help
pre-operative assessment of MSK tumours
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soft tissue contrast
CT MRI T1 MRI T2 fat sat
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soft tissue contrast
CT MRI T1 MRI T2 fat sat
tumour proximal humerus rim of calcification best
seen on CT soft tissue anatomy best on MR tumour
best seen on T2 MR image
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Magnetic Resonance Imaging (MRI)

• disadvantages
• contraindications
• orbital metallic foreign bodies
• pacemakers
• neurostimulatory devices
• claustrophobia
• 1st trimester theoretical risk
• artefacts from ferromagnetic objects
• imaging of osseous anatomy, fractures and
  calcification lacking

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CT
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MRI
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interlocking intramedullary nail distal femur
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complex hip surgery causing artefact on MRI
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MSK MRI at Mount Sinai Hospital and the
University Health Network
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• routine sequences for MRI knee
• menisci
• ligaments
• muscles
• tendons
• cartilage
• bone
• effusion
• loose bodies
• bursae

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Approach to fractures
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Ideally include joint above and below,
particularly when there are paired bones i.e.
tibia and fibula / radius and ulna
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Description of fracture

• closed vs. open (compound)
• simple vs. comminuted (complex)
• extra-articular vs. intra-articular
• path of the fracture line
• position of fracture

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Closed (no communication with the outside
environment) vs. open or compound fracture
(communication with the outside environment)
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Simple vs. Comminuted (complex) - two vs. more
than two bone fragments
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Extra-articular vs. intra-articular Intra-articula
r fractures involve the articular surface of the
adjacent joint
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Path of the fracture line
transverse oblique spiral longitudinal
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Path of the fracture line
transverse oblique spiral longitudinal
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Position of fracture

• Angulation - degree of angular deformity created
  by fracture fragments
• Displacement - is a change in the anatomic axis
  of one fragment with respect to another (as
  produced with side-to-side movement)
• Distraction - is a separation of fragments that
  have been pulled apart
• Impaction - occurs when fragments have been
  driven together
• Foreshortening - occurs when fragments override
  each other

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position of fracture
medial lateral lateral / valgus
medial / varus displacement
displacement angulation angulation
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position of fracture
internal external overriding with
distraction rotation
rotation foreshortening
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Fractures in children

• Plastic Bowing - fracture without disruption of
  cortex
• Torus - buckled cortex
• Greenstick - cortex broken on one side of the
  bone and only bent or buckled on the other side
• Salter-Harris fracture - a fracture which
  involves an open growth plate

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plastic bowing torus / buckle greenstick
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Torus / buckle fracture
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Torus / buckle fracture
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Greenstick fracture
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Salter Harris Classification of Growth Plate
Fractures
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Salter Harris Classification of Growth Plate
Fractures
S A L T R
slipped above lower through ruined
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Salter Harris type 2 fracture
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Salter Harris type 3 fracture
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Special fractures

• Fatigue fracture
• summation of microfractures caused by repeated
  trauma (frequently seen in athletes)
• normal bone abnormal load
• Insufficiency fracture
• osteoporotic / osteomalacic bone fractured by
  normal stress
• abnormal bone normal load
• Pathologic fracture
• fracture which occurs in a bone already weakened
  by a pathologic abnormality which may be either
  benign or malignant.

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Special fractures
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Fatigue fracture 3rd metatarsal (march fracture)
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Insufficiency fracture calcaneus
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Insufficiency fracture femoral neck
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Pathological fractures
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Approach to Bony Lesions
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Approach to Bony Lesions

• Where
• Lytic vs. sclerotic
• Margins
• Matrix
• Overlying cortex
• Periosteal reaction
• Soft tissue mass
• Pathological fracture

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where location, location, location
diaphyseal
metaphyseal
epiphyseal
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lucent bony lesions

• epiphyseal
• Chondroblastoma
• GCT
• Geode
• Osteomyelitis

Fibrous Dysplasia Osteoblastoma Giant Cell
Tumor Metastasis / Myeloma Aneurysmal Bone Cyst
Chondroblastoma / Chondromyxoid Fibroma
Hyperparathyroidism (brown tumors) / Hemangioma
Infection Non-ossifying Fibroma Eosinophilic
Granuloma / Enchondroma Solitary Bone Cyst
F O G M A C H I N E S
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Lytic vs. sclerotic
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Margins
geographic ill defined moth-eaten
permeative
less aggressive more aggressive
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geographic well defined thin sclerotic border
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geographic no sclerotic border ill defined
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moth-eaten multiple ill defined foci of lucency
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permeative - boundary between normal and
abnormal bone lost
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Margins
geographic ill defined moth-eaten
permeative
less aggressive more aggressive
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Matrix

• none - lytic / lucent
• fibrous - hazy, ground glass
• cartilaginous - calcification, punctate,
  popcorn, rings and whorls
• osseous - dense, bony trabeculae, cloud-like,
  mashed potatoes

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none fibrous cartilaginous osseous
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Periosteal reaction

• non aggressive
• none
• smooth
• aggressive
• lamellated (onion skinning)
• sunburst / hair on end
• Codman's triangle

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none
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smooth
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onion skinning
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sunburst
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hair on end
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Codmans triangle
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large partly ossified soft tissue mass
surrounding the distal femoral diaphysis poorly
marginated patchy sclerosis in the underlying
bone irregular circumferential periosteal
reaction
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MRI local staging for surgical planning
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staging for distant metastases
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staging for distant metastases
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advances in limb preserving surgery
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Approach to Arthritis

• soft tissues
• (swelling, calcification)
• bone density
• joint spaces
• erosions
• new bone
• (osteophytes, periostitis)
• pattern
• symmetry

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Approach to Arthritis

• osteoarthritis
• erosive arthritis
• rheumatoid arthritis
• psoriatic arthritis
• gout
• infective

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Osteoarthritis

• DIPs, PIPs, 1st CMC, STT
• osteophytes
• asymmetric joint space narrowing
• subchondral sclerosis
• subchondral cysts
• no marginal erosions
• done density preserved

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Osteoarthritis
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Osteoarthritis
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Osteoarthritis
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Osteoarthritis
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Osteoarthritis
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Osteoarthritis
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Osteoarthritis
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Osteoarthritis
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Osteoarthritis
subchondral cyst / geode vs erosion
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Osteoarthritis
subchondral cyst / geode vs erosion
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Osteoarthritis
subchondral cyst / geode vs erosion
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Setting sun sign of erosion
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Geode
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Geode
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Geode
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Erosive arthritis
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erosions
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erosions
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Rheumatoid arthritis

• wrist, MCPs, PIPs
• DIPs spared
• symmetrical
• osteopenia
• marginal erosions
• diffuse joint space narrowing
• fusiform soft tissue swelling
• subluxations

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Rheumatoid arthritis
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Rheumatoid arthritis
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Rheumatoid arthritis
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Rheumatoid arthritis
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Psoriatic arthritis

• hands gt feet
• DIPs predominantly (also PIPs and MCPs)
• preservation of bone density
• periostitis
• sausage digit
• erosion of terminal tufts

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Psoriatic arthritis
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Psoriatic arthritis
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Psoriatic arthritis
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Psoriatic arthritis
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Psoriatic arthritis pencil in cup
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Gout

• asymmetric
• most commonly at 1st MTP joint
• olecranon bursitis common
• punched out erosions with overhanging edges
  (rats bite)
• lumpy bumpy soft tissue swelling
• dense soft tissue deposits (tophi)

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Gout
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Gout olecranon bursitis
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Gout
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Infectious arthritis

• single joint
• joint effusion
• periarticular osteopenia
• destruction of articular cartilage
  and sub-articular cortex
• rapid course
• usually staph. aureus

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Infectious arthritis
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Infectious arthritis
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• Modalities of MSK
• Approach to fractures
• Approach to bony lesions
• Approach to arthritis