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Introduction to Limb
Imaging 1
RAH Radiology
Topics for today
Overview:
– Film quality
– Anatomy
– Fractures
Case examples/quiz
Warnings:
This is a big topic. Importan...
Topics for next session
Overview:
– Other modalities
– Soft tissues
– Osteoarthritis
– Bone tumours?
Case examples/quiz
Overview:
– Film quality
– Anatomy
– Fractures
This is a frontal x-ray of the left
upper arm.
While there are standard tec...
Overview:
– Film quality
– Anatomy
– Fractures
Instead, most limb x-ray quality
issues relate to positioning.
Musculoskele...
Overview:
– Film quality
– Anatomy
– Fractures
This is often worse in children.
Achieving diagnostic views in young
childr...
Overview:
– Film quality
– Anatomy
– Fractures
The general rule of thumb is that
every study of a limb or joint should
hav...
Overview:
– Film quality
– Anatomy
– Fractures
The anatomy of the long bones is
fairly simple.
Every long bone has the sam...
Overview:
– Film quality
– Anatomy
– Fractures
Each part of a bone develops from an
ossification centre. Non-calcified
mat...
Overview:
– Film quality
– Anatomy
– Fractures
There are several different methods
to describe the long bones. The
easiest...
Overview:
– Film quality
– Anatomy
– Fractures
The “ends” of the bones are a but
trickier because they have specific
names...
Overview:
– Film quality
– Anatomy
– Fractures
The articular surfaces are covered in
cartilage, which protects the joint.
...
Overview:
– Film quality
– Anatomy
– Fractures
A good rule of thumb:
If it is a single rounded bulge, call it
the head.
If...
Overview:
– Film quality
– Anatomy
– Fractures
The other bones are also a bit more
complex, and have named parts.
In the h...
Overview:
– Film quality
– Anatomy
– Fractures
The flat bones are quite difficult to
assess, because they have many
overla...
Overview:
– Film quality
– Anatomy
– Fractures
The scapula can be divided into
broad regions:
• Scapula spine
• Supraspinu...
Overview:
– Film quality
– Anatomy
– Fractures
The neck of femur is a common site
of fracture of the elderly, as injuries
...
Overview:
– Film quality
– Anatomy
– Fractures
The blood supply to the head of the
femur is mostly via capsular vessels.
T...
Overview:
– Film quality
– Anatomy
– Fractures
The most common reason to perform
limb imaging is to look for fractures.
Di...
Overview:
– Film quality
– Anatomy
– Fractures
• Identifying fractures
• Displaced fractures can be seen
with a cortical s...
Overview:
– Film quality
– Anatomy
– Fractures
• Identifying fractures
• Undisplaced fractures are difficult
to appreciate...
Overview:
– Film quality
– Anatomy
– Fractures
• Identifying fractures
• Repeat imaging in two weeks
usually reveals an oc...
Overview:
– Film quality
– Anatomy
– Fractures
• Describing fractures
The major treatment decision for
fractures is whethe...
Overview:
– Film quality
– Anatomy
– Fractures
“Important” features:
• Degree of displacement
• Location of fracture
• Com...
“Important” features:
• Degree of displacement
A significantly displaced fracture will
not heal well (or at all if the fra...
“Less important” features:
• Direction of displacement
The direction of displacement may
suggest something about the
mecha...
“Less important” features:
• Tilt
The angulation or tilt through the
fracture is rarely important.
Most radiologists don’t...
“Important / less important” features:
• Location of fracture
The part of the bone involved almost
never decides managemen...
“Important” features:
• Comminution / fragmentation
Fractures with multiple fragments
often heal poorly. These injuries ar...
“Important” features:
• Compound / open
High impact trauma can push the
fracture through the skin.
These injuries require ...
“Less important” features:
• Fracture orientation
The orientation of a fracture is often
described, but has very little im...
Overview:
– Film quality
– Anatomy
– Fractures
• Special cases
The best way to assess the flat bones
is to follow the curv...
Overview:
– Film quality
– Anatomy
– Fractures
• Special cases
Like the pelvis, the scapula is best
assessed by following ...
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RAH Med 4 Ortho - Limb Imaging 1

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RAH Med 4 Ortho - Limb Imaging 1

  1. 1. Introduction to Limb Imaging 1 RAH Radiology
  2. 2. Topics for today Overview: – Film quality – Anatomy – Fractures Case examples/quiz Warnings: This is a big topic. Important phrases and concepts are bolded. Many of these topics have been simplified. The intent is to deliver useful basic skills, which can be later refined.
  3. 3. Topics for next session Overview: – Other modalities – Soft tissues – Osteoarthritis – Bone tumours? Case examples/quiz
  4. 4. Overview: – Film quality – Anatomy – Fractures This is a frontal x-ray of the left upper arm. While there are standard techniques (the humerus is imaged antero- posterior by convention), magnification is not an issue, because the whole limb is so close to the detector. The x-ray beam barely diverges at all.
  5. 5. Overview: – Film quality – Anatomy – Fractures Instead, most limb x-ray quality issues relate to positioning. Musculoskeletal injuries limit movement, so many positions are hard to achieve. Most limb x-rays are taken in the neutral or anatomic position. In the example here, the arm is abducted, which may limit assessement at the shoulder joint.
  6. 6. Overview: – Film quality – Anatomy – Fractures This is often worse in children. Achieving diagnostic views in young children with fractures can be very difficult, and often traumatic. In this example the elbow is almost lateral in orientation, but the wrist appears like a frontal view. Many subtle features can be missed.
  7. 7. Overview: – Film quality – Anatomy – Fractures The general rule of thumb is that every study of a limb or joint should have two orthogonal (at right angles) views. This usually means a frontal and lateral view. Oblique views reveal anatomy that is obscured by other structures. For example, the radial head view lifts the radius from behind the ulna.
  8. 8. Overview: – Film quality – Anatomy – Fractures The anatomy of the long bones is fairly simple. Every long bone has the same features, although they are confusingly called different things. The major “parts” are all defined in relation to the developmental anatomy.
  9. 9. Overview: – Film quality – Anatomy – Fractures Each part of a bone develops from an ossification centre. Non-calcified matrix is formed first, and this later calcifies. These growth centres are usually: • Shaft (in utero) • Proximal and distal, articular and ligament attachments In this wrist there is partial ossification of the distal radius, and no ossification of the distal ulna.
  10. 10. Overview: – Film quality – Anatomy – Fractures There are several different methods to describe the long bones. The easiest way is to identify the shaft and the proximal and distal “ends”. The shaft is the roughly parallel portion of the bone, before it flares at either end. The shaft is easiest to describe by splitting it into proximal, middle and distal thirds.
  11. 11. Overview: – Film quality – Anatomy – Fractures The “ends” of the bones are a but trickier because they have specific names in different bones. The flaring portion is called the metaphysis, although most doctors are happy for you to include this in the shaft if that is hard to remember. The most important part of the end of a long bone is the articular surface.
  12. 12. Overview: – Film quality – Anatomy – Fractures The articular surfaces are covered in cartilage, which protects the joint. The adjacent bone can always be described as sub-articular. Otherwise, the various ends of bones have a range of names, and most of the associated bony lumps have names too, so there isn’t an easy way to learn these details. Examples are labelled to the left. Femoral condyles Tibial plateau Fibular head
  13. 13. Overview: – Film quality – Anatomy – Fractures A good rule of thumb: If it is a single rounded bulge, call it the head. If it has multiple bulges … rote learning is the only way. Use Google as needed. Humeral head Radial head Humeral condyles Olecranon
  14. 14. Overview: – Film quality – Anatomy – Fractures The other bones are also a bit more complex, and have named parts. In the hands and feet: • The carpals and tarsals are all uniquely named (for example, the “lunate”). • The metacarpals / tarsals and phalanges are small “long bones”, with a base (proximal), a shaft, and a head (distal).
  15. 15. Overview: – Film quality – Anatomy – Fractures The flat bones are quite difficult to assess, because they have many overlapping parts. The pelvis can be divided into broad regions: • Iliac wing • Acetabular • Pubic rami • Sacrum
  16. 16. Overview: – Film quality – Anatomy – Fractures The scapula can be divided into broad regions: • Scapula spine • Supraspinus • Scapula body / infraspinus • Glenoid Not shown: coracoid process and acromion.
  17. 17. Overview: – Film quality – Anatomy – Fractures The neck of femur is a common site of fracture of the elderly, as injuries here have poor outcomes without surgical management. There are multiple named regions, but the important distinction in trauma is whether the fracture is within the joint capsule. The head and proximal neck of femur are intra- capsular. The distal neck and trochanteric region are not.
  18. 18. Overview: – Film quality – Anatomy – Fractures The blood supply to the head of the femur is mostly via capsular vessels. These can be disrupted by trauma, leading to avascular necrosis (AVN). This case shows early AVN after an inadequately treated subcapital fracture. The femoral head is deformed and sclerotic. Case contributed by Dr Chris O’Donnell at Radiopaedia.org
  19. 19. Overview: – Film quality – Anatomy – Fractures The most common reason to perform limb imaging is to look for fractures. Dislocations are less common and are usually more clinically apparent, so the imaging is more for prognosis than diagnosis; looking for associated fractures.
  20. 20. Overview: – Film quality – Anatomy – Fractures • Identifying fractures • Displaced fractures can be seen with a cortical step. Jagged or angular lines are rarely seen anatomically. • Fracture “lines”, seen as linear low densities crossing the bone are untrustworthy. Our brains misinterpret them. Note the black lines over the pelvis on this study, which are not fractures.
  21. 21. Overview: – Film quality – Anatomy – Fractures • Identifying fractures • Undisplaced fractures are difficult to appreciate, even for radiologists. The most useful sign will always be a tiny bit of cortical displacement. • Associated features like joint effusions and soft tissue swelling can help. There is an elbow joint effusion in this study, consistent with an occult fracture.
  22. 22. Overview: – Film quality – Anatomy – Fractures • Identifying fractures • Repeat imaging in two weeks usually reveals an occult fracture as the edges of the fracture becomes denser while healing. • This is usually performed if there is no risk to delaying diagnosis. • If the diagnosis cannot wait, CT, MRI or bone scan imaging is performed.
  23. 23. Overview: – Film quality – Anatomy – Fractures • Describing fractures The major treatment decision for fractures is whether they can be managed conservatively, or if they have to be fixed with an operation. This decision is about the predicted long-term function of the limb. There are many ways to describe fractures, but only some of the are relevant to this decision.
  24. 24. Overview: – Film quality – Anatomy – Fractures “Important” features: • Degree of displacement • Location of fracture • Comminution / fragmentation • Open / compound injury “Less important” features: • Direction of displacement • Tilt • Location of fracture • Fracture orientation
  25. 25. “Important” features: • Degree of displacement A significantly displaced fracture will not heal well (or at all if the fracture margins don’t touch). Such a fracture may require internal fixation if reduction cannot be achieved otherwise. The most universal way to describe displacement is by reference to the bone itself. “There is half a bone width of displacement”.
  26. 26. “Less important” features: • Direction of displacement The direction of displacement may suggest something about the mechanism of injury. For example, posterior displacement in a distal radius fracture usually suggests a “fall onto an outstretched hand” (FOOSH). That said, the direction of displacement will almost never alter management. If you want to mention it, displacement is always described in reference to the distal fragment. “There is medial displacement by around half a bone width”.
  27. 27. “Less important” features: • Tilt The angulation or tilt through the fracture is rarely important. Most radiologists don’t mention the degree or direction of tilt unless it is clearly non-anatomic, in which case the degree of displacement is a better feature for prognosis. If you want to mention it, tilt is described in reference to the distal portion of the distal fragment. “There is mild medial tilt without displacement.”
  28. 28. “Important / less important” features: • Location of fracture The part of the bone involved almost never decides management. There are several exceptions, however. • Intra-articular - Disruption of the cartilage results in severe degeneration at the joint. • Growth plate - In a child with unfused growth plates, unrepaired damage here will impair future growth (or even halt it completely). • Blood supply - Some fractures can impair blood supply to the bone, leading to AVN.
  29. 29. “Important” features: • Comminution / fragmentation Fractures with multiple fragments often heal poorly. These injuries are often treated with surgery. The most common term used is comminution, however this can be easy to confuse with the word compound. Alternative descriptive terms include fragmentation and multi-part. “There is a multi-part fracture of the mid tibia with a full bone width of medial displacement.”
  30. 30. “Important” features: • Compound / open High impact trauma can push the fracture through the skin. These injuries require surgical management even if they can be reduced. The protective skin barrier is broken, so the wound is soiled and at high risk of infection. Open is often used as a descriptive term instead of compound.
  31. 31. “Less important” features: • Fracture orientation The orientation of a fracture is often described, but has very little impact on management. Like the direction of displacement, they can imply a mechanism of injury. Common descriptive terms are: • Transverse • Oblique • Spiral “There is a multi-part spiral fracture of the distal humerus, with one cortical width of posterior displacement.”
  32. 32. Overview: – Film quality – Anatomy – Fractures • Special cases The best way to assess the flat bones is to follow the curving lines of cortex wherever you can. These lines often cross between bones (because they represent bone thickening along the plane of mechanical loading). Jagged or angular contours suggest fracture. “There is a cortical step in the right acetabular region”.
  33. 33. Overview: – Film quality – Anatomy – Fractures • Special cases Like the pelvis, the scapula is best assessed by following the curving lines of cortex. Jagged or angular contours suggest fracture. “There are multiple cortical steps involving the scapula spine, coracoid process and glenoid”.

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