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Huang's Orthopaedic Surgery > Hip, Pelvis & Acetabulum > Flashcards

Hip, Pelvis & Acetabulum Flashcards

0
Q

What is an innominate bone?

A

The bone formed at maturity by the fusion of the ossification centres of the ilium, ischium and pubis through the triradiate cartilage

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1
Q

What structures make up the pelvic ring?

A

Sacrum and two innominate bones joined anteriorly at the pubic symphysis and posteriorly at the sacroiliac joints

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2
Q

What is the pelvic brim?

A

Structure formed by the Arcuate lines that join the sacral promontory posteriorly and the superior pubis anteriorly.

Basically it’s the pelvic inlet

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3
Q

What does the pelvic brim separate?

A

The true/lesser pelvis (containing the pelvic viscera) and the false/greater pelvis, (representing the inferior portion of the abdominal cavity)

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4
Q

Broadly speaking, which groups of ligamentous structures provide stability to the pelvis?

A

Ligaments from sacrum to ilium
Ligaments from pubis to pubis
Ligaments from lumbar spine to pelvic ring

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5
Q

What are the ligaments, running from sacrum to ilium, that provide inherent stability to the pelvis?

A

Superior to inferior:
Sacroiliac Iigament complex
- Divided into posterior (long & short) & anterior
Sacrospinous ligament:
- Lateral sacrum to ischial spine
Sacrotuberous ligament
- From posterolateral aspect of sacrum to dorsal iliac spine and ischial tuberosity

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6
Q

What are the main functions of the ligaments of the pelvis running from sacrum to innominate?

A

Sacroiliac ligament: provides most of overall stability (posterior portion)
Sacrospinous ligament: maintains rotational control of pelvis if posterior SI ligament is intact
Sacrotuberous ligament: maintains vertical stability of the pelvis

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7
Q

What is the ligament between the two pubic bones at provides stability to the pelvis?

A

Symphyseal ligament

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8
Q

What ligaments from the lumbar spine to the pelvis aid in stability?

A 
Iliolumbar ligaments (TP of L4-5 to posterior iliac crest)
Lumbosacral ligaments (TP of L5 to sacral ala)
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9
Q

What ligaments of the pelvis resist rotational forces?

A 
The transversely placed ligaments, including:
Short posterior SI ligament 
Anterior SI ligament
Iliolumbar ligament
Sacrospinous Iigament
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10
Q

What ligaments of the pelvis resist shear forces?

A

The vertical positioned ligaments, including:
Long posterior SI ligament
Sacrotuberous ligament
Lateral lumbosacral ligaments

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11
Q

What injury pattern will result in an AP force applied to the pelvis?

A

ER of hemipelvis

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12
Q

In an AP force applied to the pelvis, what ligament is generally intact?

A

Posterior SI ligaments - the hemipelvis is ER, hinging on the posterior SI ligament

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13
Q

Where is the force applied in an LC injury to the pelvis to create a stable pelvis injury?

A

Posterior half of the ilium

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14
Q

What injury results when an LC force is applied through the anterior half of the ilium?

A

IR/LC injury of the ipsilateral hemipelvis +- ER injury on the contralateral side

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15
Q

What acetabular injury are LC forces directed at the GT associated with?

A

Transverse acetabular fractures

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16
Q

What does an ER abduction force lead to?

A

Tearing of hemipelvis from sacrum.

Lead to a completely unstable fracture with triplane instability (AP, vertical shear, rotation) due to tearing to sacroiliac, sacroinous and sacrotuberous ligaments

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17
Q

Why is it important to minimize clinical exam of a suspected pelvic fracture (ie perform AC-LC test only once)?

A

So as to not disrupt any clot formed

First clot is the best clot bc:
Body has used up thrombotic factors
Thrombotic factors diluted bc of fluid resus

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18
Q

Where must you look for open fractures in pelvic injury?

A

Perineum, rectum and vagina (via rectal & vaginal exam)

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19
Q

What pelvic injuries are an AP pelvis good at looking for?

A

Anterior lesions: pubic rami fractures, symphysis displacement
SI joint and sacral fractures
Iliac fractures
L5 TP fractures

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20
Q

How do you do an inlet view of the pelvis? What is it good at looking for?

A

Patient supine and beam directed 60 deg caudally, perpendicular to the pelvic brim

Good for looking at: AP displacement of SI joint, sacrum, or Iliac wing
My determine IR deformities of the ilium and sacral impaction

21
Q

How do you do an outlet view of the pelvis? What is it good for?

A

Patient supine and beam directed deg cephalad.

Good for looking at vertical displacement of hemipelvis
May help with subtle signs of disruptions of the posterior elements (SI joint, sacrum)

22
Q

Name the radiographic signs of pelvic instability:

A

SI joint displacement of 5mm in any plane
Posterior fracture gap (rather than impaction)
Avulsion of:
- L5 TP (iliolumbar, lumbosacral
- Lateral border of sacrum (sacrotuberous ligament)
- Ischial spine (sacrospinous ligament)

23
Q

Describe the Young & Burgess classification of pelvic fracture:

A 
Based on mechanism of injury:
Lateral compression (LC)
- Type 1, 2, 3
AP compression (APC)
- Type 1, 2, 3
Vertical shear (VS)
Combined mechanical (CM)
24
Q

Describe the Y&B LC type injury:

A

Implosion of the pelvis secondary to laterally applied force
Shortens the anterior SI, sacrospinous and sacrotuberous ligaments
May see oblique fractures on pubic rami on ipsilateral or contralateral side
3 types:
- Type 1: sacral impaction on side of impact. Transverse fractures of pubic rami are stable
- Type 2: posterior iliac wing fracture (crescent) on side of impact. Variable disruption of posterior ligamentous structures so variable rotational instability. Maintains vertical stability
- Type 3: Windswept pelvis: LC-1 or 2 injury on side of impact with ER rotation injury contralaterally. SI, sacrotuberous and sacrospinous ligament injury

25
Q

Describe the Y&B APC type pelvic injury:

A

Anteriorly applied force. Results in: symphyseal diastasis, ER rotation injuries, longitudinal rami fractures
3 types:
- Type 1: 2.5cm of symphyseal diastasis. SI joint widening 2o to anterior SI lig disruption. Open book injury with IR/ER rotational instability 2o to disruption of sacrotuberous, sacrospinous and symphyseal ligament with intact posterior SI ligs. Vertical stability maintained.
- Type 3: complete disruption of symphysis, sacrotuberous, sacrospinous and SI ligaments. Results in extreme rotational instability and lateral displacement. No cephaloposterior displacement. Completely unstable type with highest rate of associated vascular injury/blood loss

26
Q

Describe the Y&B VS type injury:

A

Vertically or longitudinally applied force.
Typically, compete disruptions of symphysis, sacrotuberous, sacrospinous, SI ligaments.
Extreme instability mostly in cephaloposterior direction bc of inclination of pelvis
High incidence of neurovascular and vascular injuries

27
Q

Describe the Y&B CM type injury:

A

Combination of injuries often resulting from crush injuries.
Most common are VS and LC

28
Q

Describe the Tile classification of pelvic fractures:

A

Type A: stable
- A1: fracture of pelvis not involving the ring; avulsion injuries
- A2: stable, minimal displacement of the ring
Type B: rotationally unstable, vertically stable:
- B1: ER rotation instability: open book injury
- B2: LC injury: IR instability; ipsilateral only
- B3: LC injury: bilateral rotational instability (bucket handle)
Type C: rotationally and vertically unstable
- C1: unilateral injury
- C2: bilateral injury: one side rotationally unstable, the other vertically unstable
-C3: bilateral injury. Both sides rotationally and vertically unstable with an associated acetabular fracture

29
Q

Name 7 factors increasing mortality in pelvic ring injury:

A
  • Type of injury: posterior disruption is associated with higher mortality (APC-3, VS, LC-3)
  • High injury severity score
  • Associated injuries (head and abdominal: 50% mortality)
  • Hemorrhagic shock on admission
  • Requirement for large quantities of blood
  • Perineal lacations
  • Increased age
30
Q

What is a Morel-Lavalle lesion?

A

Skin degloving injury associated with pelvic injuries.

Colonized in up to 1/3 of cases
Requires thorough debridement before definitive fixation

31
Q

Which Y&B fracture types are amenable to non-operative fixation?

A

Most LC-1 and APC-1 fractures

Gapping of the pubic symphysis < 2.5cm (APC-1)

32
Q

What are absolute indications of operative management of pelvic fractures?

A

Open pelvic fractures
Pelvic fractures with associated visceral perforation requiring operative intervention
Open-book pelvic fractures or vertically unstable fractures with associated patient hemodynamics instability

33
Q

Name 5 relative indications for operative management of pelvic fractures:

A 
Symphyseal diastasis >2.5cm (indicates loss of mechanical stability aka disruption of ligaments)
Leg-length discrepancy >1.5cm
Rotational deformity
Sacral displacement >1cm
Intractable pain
34
Q

What are the clinical signs for associated urethral injury in pelvic fractures?

A

Blood at the meatus

High riding prostate on rectal exam

35
Q

What is the management of associated urethral and bladder injuries of pelvic fractures?

A

Urethral: retrograde urethrogram in suspected patients with repair on a delayed basis
Bladder:
Intraperitoneal bladder ruptures: repaired
Extraperitoneal bladder ruptures may be observed

36
Q

What are the Judet-Letournel acetabular fracture patterns?

A 
10 fracture patterns, 5 elementary, 5 associated 
Elementary:
- Posterior wall
- Posterior column
- Anterior wall
- Anterior column
- Transverse
Associated:
- T-shaped 
- Posterior column & posterior wall
- Transverse & posterior wall
- Anterior column & posterior hemitransverse
- Both column
37
Q

What does an obturator oblique radiograph look at?

A

Anterior column

Posterior wall

38
Q

What does the iliac oblique radiograph look at?

A

Posterior column

Anterior wall

39
Q

Which acetabular fractures involve fractures of the obturator ring?

A

Both column

T-Type

40
Q

Which acetabular fracture types involve disruption of both the iliopectineal and ilioischial lines?

A 
Both column
T-Type
Transverse
Transverse + posterior wall
Anterior + posterior hemitransverse
41
Q

What is a spur sign?

A

Radiographic sign pathognomonic for both column acetabular fracture

  • Indicates disruption of sciatic buttress and dissociation of the acetabulum from the axial skeleton
  • Shows up as a shard of bone extending posteriorly at the level of the superior acetabulum
42
Q

In which spatial orientation is the transverse acetabular fracture oriented in? Why?

A

(Closer to) the sagittal plane

  • Because it is transverse in relation to the acetabulum, which is normally tilted inferiorly and anteverted, resulting in the fracture line being closer to the sagittal plane
  • It is transverse if you look at the acetabulum En face
43
Q

What is an APC IIa & IIb injury?

A

APC IIa: Posterior SI ligaments intact as 1cm VERTICAL displacement of pubis on dynamic stress view
- In APC IIa, do not need posterior stabilization, whereas APC IIb requires posterior stabilization

44
Q

What is the Multiple Binder method of pelvic stabilization?

A

In addition to pelvic binding at the GT, additional binding at the femur, knees and ankles to provide secondary, indirect closing of the pelvis

45
Q

What should be used to hold a pelvic binder in place?

A

Clamps. Do not tie a knot as this will cause pressure points/sores

46
Q

What types of bleeds do angiography and pelvic binding address? Can they be used together?

A

Angiography: arterial bleed
Pelvic binding: venous bleeds/bone ooze
They can, and SHOULD, be used in concert

47
Q

What is a locked symphysis?

A

LC type injury resulting in symphysis tear and the intact pubic body crossing over to the uninjured side and getting locked in the obturator ring

48
Q

How can you reduce a locked symphysis?

A

Grapsing iliac crests, using a figure-4 position.
Open reduction if this fails
Careful as there is usually a bladder or urethral injury

49
Q

What is a tilt fracture?

A

Superior ramus rotates through the symphysis and is pushed posteriorly and inferiorly into the perineum

50
Q

What are the common sequelae of pelvic fractures?

A 
Dyspareunia (56% of women & all patients with bladder rupture)
Sexual dysfunction (61% men) & erectile dysfunction (19% men) - this is not helped with fixation of pelvis
Post-traumatic pain, up to 90% depending on type
51
Q

What is the ideal placement for cannulated screws of femoral neck fractures?

A

3 screws in an inverted triangle position.

1st: posteroinferior (adjacent to calcar)
2nd: posterosuperior
3rd: anterosuperior

Huang's Orthopaedic Surgery (15 decks)

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