Trauma - Pelvis/Acetabulum (Complete) Flashcards
What is the clinical evaluation of a pelvic fracture?
[CORR trauma]
- ATLS
- Observation
- Open
- Blood at the meatus
- Morell-Lavalle
- Pelvis stability
- LLD
- Rectal exam
- Blood
- Tone
- High riding prostate
- Distal NV exam
When and how is a retrograde urethrogram performed?
- Insert foley catheter ~2cm into urethra
- Inflate balloon ~2-3mL of water
- Stretch penis to straighten and hold glans to maintain catheter in place
- Inject 20-30mL of water soluble contrast dye taking an xray after each 10mL
- If demonstrates intact urethra the balloon is deflated then advanced into the bladder and reinflated
- To perform cystogram:
- Inject 300mL of diluted contrast dye (1:1 with saline)
- Clamp the catheter and obtain xray
- Drain the bladder completely and repeat xray
- Alternative to bedside cystogram is a CT cystogram
- Does not require draining bladder
- Abnormal retrograde urethrogram
- Extravasation or urethral occlusion
- Consult urology
- Abnormal cystogram
- Extravasation
- Intraperitoneal extravasation
- Requires surgery
- Extraperitoneal extravasation
- Requires bladder decompression with foley
- Intraperitoneal extravasation
In cases of open pelvis fractures, what additional surgical procedure needs to be considered?
[Rockwood and Green 8th ed. 2015]
Diverting colostomy – 50% death rate if not done
What are the recommended routine radiographs for a pelvis fracture?
[J Orthop Trauma 2014;28:48–56]
- AP pelvis
- Inlet
- Outlet views
How do you obtain an inlet and outlet view?
[J Orthop Trauma 2014;28:48–56]
- Traditionally:
- Inlet - 45 degree caudal tilt
- Outlet - 45 degree cranial tilt
- Current recommendation:
- Inlet - 25 caudal tilt
- Outlet - 60 degree cranial tilt
What are the options for external fixation for pelvis fractures and how do you insert the pins?
[J Orthop Trauma 2014;28:48–56]
- Iliac crest/wing external fixation pins
* Start point- 3-4cm posterior to the ASIS centred between the inner and outer tables
* Fluoro image used: - Obturator outlet view
* Pin direction - Superior to inferior directed towards the supraacetabular bone
- 3-4cm posterior to the ASIS centred between the inner and outer tables
- Supraacetabular external fixation pins
- Start point
- Center of the teardrop visualized on obturator outlet view
- At least 2cm above superior acetabulum
- Fluoro image used:
- Obturator outlet view for start point
- And for visualization of pin along its entire length between inner and outer tables
- Iliac oblique view for depth and to ensure ~1-2cm above sciatic notch
- OO (start)–>IO (length/location)–>OO (trajectory)
- Obturator outlet view for start point
- Pin direction
- AIIS to PIIS
What are the advantages and disadvantages of supraacetabular ex-fix pins (Hannover technique)?
[Rockwood and Green 8th ed. 2015]
Advantages
- Pins are out of the way of abdominal procedures
- Two pins are sufficient (one on either side)
- Fixation is excellent
- Allows for direction of closure of open book injury in the same plane
- Biomechanically superior in resisting rotational forces and equal control of flexion/extension forces compared to iliac crest pins
Disadvantages
- More dependent on fluoro
How do you classify pelvic fractures?
[JAAOS 2013;21:448-457]
- Young-Burgess Classification
- Lateral compression (LC)
- LC-I
- Pubic rami fracture + sacral ala buckle fracture
- LC-II
- Pubic rami fracture + crescent fracture
- LC-III
- Windswept pelvis
- ***NOTE: pubic rami fracture is horizontal
- LC-I
- Anterior-Posterior compression (APC)
- APC-I
- Widening of the pubic symphysis <2.5cm
- APC-II
- Widening of the pubic symphysis >2.5cm + widening of anterior SI
- Posterior SI remains aligned
- Widening of the pubic symphysis >2.5cm + widening of anterior SI
- APC-III
- Complete disruption of the posterior pelvis
- Anterior and posterior SI joint disruption OR nonimpacted posterior fracture
- Complete disruption of the posterior pelvis
- APC-I
- Vertical shear (VS)
- Vertical displacement of a hemipelvis with complete disruption of the SI ligaments or a fracture through the sacrum or ilium
- Combined
2. Tile classification [Rockwood and Green 8th ed. 2015] - Type A – Pelvic Ring Stable
- A1
- Fractures not involving the ring
- Eg. avulsion, iliac wing or crest fractures
- Fractures not involving the ring
- A2
- Stable minimally displaced fractures of the pelvic ring
- A1
- Type B – Pelvic Ring Rotationally Unstable, Vertically Stable
- B1
- Open book
- B2
- Lateral compression, ipsilateral
- B3
- Lateral compression, contralateral, or bucket handle-type injury
- B1
- Type C – Pelvic Ring Rotationally Unstable and Vertically Unstable
- C1 = unilateral
- C2 = bilateral
- C3 = associated acetabular fracture
What radiographic feature has been described as a ‘sentinel sign’ of a vertical shear injury?
[Rockwood and Green 8th ed. 2015]
L5 transverse process fracture
What is considered pathognomonic radiographic feature for lateral compression injuries?
[Rockwood and Green 8th ed. 2015]
Rami fractures in the transverse plane on the inlet view
In a hypotensive patient with a pelvic ring fracture and no other sources of hemorrhage, what options should be considered to control the bleeding?
[Rockwood and Green 8th ed. 2015]
- Stabilization of unstable pelvic ring fractures
- Traction
- Pelvic binder
- External fixation
- Military antishock trousers
- Angiographic embolization
* Consider when contrast extravasation evident on CT - Retroperitoneal pelvic packing
What vessels are most commonly involved in arterial bleeds associated with pelvic ring fractures?
[Rockwood and Green 8th ed. 2015]
Branches of the internal iliac
- Superior gluteal artery
- Lateral sacral
- Internal pudendal
- Inferior gluteal
- Obturator artery
What are indications for nonoperative management of pelvic ring fractures?
[Rockwood and Green 8th ed. 2015]
- Stable pelvic ring fractures
- Stable sacral fractures
- Comorbidities precluding surgery
- Poor bone quality where screw purchase may be problematic
- Low-energy osteoporotic pelvic ring fracture
What are indications for anterior pelvis ring stabilization?
[Rockwood and Green 8th ed. 2015]
- >2.5cm of symphysis diastasis on either static or dynamic (EUA) imaging
- Augment posterior fixation in VS fractures
- Augmentation of posterior fixation in completely unstable pelvic fractures
- Augmentation of posterior fixation in osteopenic bone
- Significantly displaced rami fractures
- Locked symphysis
- Straddle fractures
- Pain and inability to mobilize (relative)
What are relative indications for posterior pelvic ring stabilization?
- Complete disruption of the SI joint
* Anterior and posterior SI ligaments - Vertical displacement
- Displaced crescent fractures
* Iliac wing fractures that enter and exit both crest and greater sciatic notch or SI joint - Displaced sacral fracture
- Complete sacral fractures with potential for displacement
- Lumbopelvic disassociation
What is the mainstay of anterior approaches for internal fixation of the pelvis?
[Rockwood and Green 8th ed. 2015]
Pfannenstiel incision
- Transverse incision 2cm above pubic symphysis
- Length is from one external inguinal canal to the other
- Allows identification and protection of spermatic cord/round ligament
- Linea alba is then split longitudinally
- Symphysis and pubic bodies are exposed
- Carefully separate the bladder from the posterior pubis and protect with a large malleable retractor
What are indications for surgical fixation of pubic rami fractures?
[Rockwood and Green 8th ed. 2015]
- Rami fractures associated with vertical shear injury
- Augmentation of posterior fixation when there is considerable instability
What are the surgical options for pubic rami fractures?
- Pelvic reconstruction plates
- Ex-fix
- Antegrade or retrograde percutaneous screw fixation
When should an antegrade screw be chosen over a retrograde screw for fixation of pubic rami fractures?
[Rockwood and Green 8th ed. 2015]
- When the fracture is:
- Lateral, near the pubic root
- In the middle of the ramus
- If the patient is morbidly obese
***Retrograde screws are for medially based fractures
What structures are at risk when placing a percutaneous screw for pubic rami fixation?
[Rockwood and Green 8th ed. 2015]
- External iliac vessels (superior)
- Acetabulum (inferior)
- Bladder (deep)
- Corona mortis (deep)
What are the important technical points for antegrade percutaneous screw fixation for pubic rami fractures?
[Rockwood and Green 8th ed. 2015]
- Screw type
* Cannulated partially threaded 6.5 or 7.3mm screw - Start point
* Midpoint on a line drawn between the tip of the GT and a spot about 4cm posterior to ASIS - Fluoro views used
* Obturator outlet view and inlet view to confirm within bone
What are the important technical points for retrograde percutaneous screw fixation for pubic rami fractures?
[Rockwood and Green 8th ed. 2015]
- Screw type
- 3.5 or 4.5 screw in AO lag screw fashion
- Or 6.5 or 7.3mm cannulated partially threaded screw
- Start point
* Incision made over contralateral pubic tubercle with blunt dissection towards ipsilateral pubic tubercle - Fluoro views used
* Obturator outlet view and inlet view to confirm within bone
How are LC-2 crescent fractures subclassified and what are the surgical options?
[Rockwood and Green 8th ed. 2015]
SI joint is divided into thirds (Day classification)
- Type I
- Anterior third
- Pelvic recon plates and lag screws
- Anterior approach
- Or LC-II screw
- Same path as supraacetabular ex-fix pin
- Type II
- Middle third
- Lag screws from PIIS directed toward sciatic buttress +/- recon plate for neutralization
- Posterior approach
- Type III
- Posterior third
- Lag screw (posterior approach) and SI screw
***Note = the crescent fragment is considered the ‘constant fragment’ and the ilium should be reduced to it
Successful closed reduction of an SI joint dislocation is required for percutaneous SI screw placement, what techniques can be used to obtain the closed reduction?
[Rockwood and Green 8th ed. 2015]
- IRTOTLE technique
* Internal rotation and taping of the lower extremities - Sheet wrapped at level of GTs
- Sheet wrapped around pelvis with holes cut for screw placement
What radiographic views are used to place an SI screw?
[Rockwood and Green 8th ed. 2015]
- Inlet view – AP screw position
- Outlet view – superior/inferior screw position
- Lateral sacral view (optional) useful to determine start point
What are the technical points of achieving a true inlet and outlet pelvis view?
[JBJS REVIEWS 2018;6(1):e7]
- Inlet view
* Superimposition of the anterior S1 and S2 alar opacities - Outlet view
* Superior portion of the pubic body and rami should be superimposed over the S2 sacral foramina
What are the radiographic landmarks on a lateral sacral view?
[Rockwood and Green 8th ed. 2015]
- Iliac cortical density (sacral ala)
- The entry point should be:
- Anterior in S1
- Inferior to the iliac cortical density (ICD)
- Parallels the sacral alar slope, usually slightly caudal and posterior
- Marks the anterosuperior boundary of the safe zone for an iliosacral screw which may injure the L5 nerve root if it penetrates this cortex. [AOfoundation]
- Sacral promontory
- Anterior aspect of the sacral canal
- Vestigial S1-S2 disc space
* Corresponds to S1 foramen
What are the important technical points for percutaneous SI screw placement?
[Rockwood and Green 8th ed. 2015]
- A 6.5, 7.3 or 8.0mm partially threaded cannulated screw is used with washer
- The screw is placed perpendicular to the SI joint
- The start point for the guidewire is confirmed on inlet, outlet and lateral sacral (optional) views
- Guidewire is advanced alternating between inlet and outlet views
- Ensuring on inlet view that it is anterior to the sacral canal and posterior to the sacral promontory
- Ensuring on outlet view that it is above the S1 foramen and below the superior endplate of S1
- Depth of guidewire is just adjacent or lateral to the opposite S1 sacral foramen on the outlet view
- After screw is placed, position is confirmed on standard AP pelvis, inlet and outlet views to confirm proper placement of screw in the S1 corridor
What are the features of sacral dysmorphism?
[Rockwood and Green 8th ed. 2015]
- Upper sacrum being collinear with the iliac crest (normally below)
- Presence of mammilary processes in the alar region
- Uppermost sacral foramina are larger, misshapen and irregular (i.e. oval, not circular)
- Residual disc space between S1 and S2
- Alar slope is more acute on lateral sacral view
* i.e. Not collinear with iliac cortical density - Tongue-in-groove SI articulation seen on CT
- Anterior cortical indentation is present in the dysmorphic sacral ala
NOTE: sacral dysmorphism present in up to 44% of population
How does sacral dysmorphism change SI screw placement?
[Rockwood and Green 8th ed. 2015]
- Screw must be placed obliquely in cephalad direction into S1
- Prevents through-and-through transiliac fixation
- S2 may be used instead of S1 for iliosacral or transiliac screw
How does the fracture pattern affect planning for SI screws?
- Sacral fractures
* Longer screws that traverse the spinopelvic region preferred - Pure SI joint instability
* Shorter screws - Comminuted sacral fractures
- Avoid compression of the neural foramen
- Consider fully threaded screw
- Simple sacral fractures
* Partially threaded screws - Vertically unstable, comminuted fractures
* SI screws alone do not provide adequate fixation
What forms the anterior column and posterior column?
[Rockwood and Green 8th ed. 2015]
Anterior column
- Anterior half of the iliac wing
- Adjacent pelvic brim
- Anterior half of the acetabular articular surface
- Including anterior wall
- Superior pubic ramus
Posterior column
- Begins at the superior aspect of the greater sciatic notch
- Includes the bone adjacent to the greater and lesser sciatic notches
- Posterior half of the acetabular articular surface
- Including posterior wall
- Ischial tuberosity
***Note: the columns are connected at the inferior aspect by the ischiopubic ramus and medially at the quadrilateral plate
- Sciatic buttress is what links the two columns to the SI articulation
What are the recommended routine radiographs for an acetabulum fracture?
[Instr Course Lec 2015; 64-139]
- AP pelvis
- Judet views
* Obturator oblique and iliac oblique views
What are the 6 acetabular landmarks seen on an AP radiograph?
[Instr Course Lec 2015; 64-139]
- Ilioischial line
- Iliopectineal line
- Anterior rim
- Posterior rim
- Roof
- Teardrop
Describe the Letournel Classification of acetabular fractures
[Rockwood and Green 8th ed. 2015]
- Elementary fracture patterns (5)
- Posterior wall
- Posterior column
- Anterior wall
- Anterior column
- Transverse
- Associated fracture patterns (5)
- Posterior column and posterior wall
- Transverse and posterior wall
- Anterior column (or wall) and posterior hemitransverse
- T-shaped
- Both column
Based on radiographs alone how do you determine which acetabular fracture pattern exists?
[JAAOS 2018;26:83-93]
- Both ilioischial and iliopectineal lines disrupted
- Obturator ring intact
- Posterior wall fracture seen on the obturator oblique view
- = Transverse and posterior wall
- Posterior wall fracture not seen on the obturator oblique view
- = Transverse fracture
- Posterior wall fracture seen on the obturator oblique view
- Obturator ring not intact
- Fracture does not involve ilium
- = T-type fracture
- Fracture does involve the ilium
- Spur sign seen on obturator oblique view
- = Associated both column
- Spur sign not seen on obturator oblique view
- = Anterior column posterior hemitransverse
2. Only Iliopectineal line disrupted = anterior column
3. Only Ilioischial line disrupted
- = Anterior column posterior hemitransverse
- Spur sign seen on obturator oblique view
- Fracture does not involve ilium
- Posterior wall fracture seen on the obturator oblique view
- = Posterior column and posterior wall
- Posterior wall fracture not seen on the obturator oblique view
- = Posterior column fracture
- Both ilioischial and iliopectineal lines intact
- Fracture seen on the obturator oblique view
- = Posterior wall fracture
- Fracture seen on the iliac oblique view
- = Anterior wall fracture
*****Liew 2-Column Algorithm (Based on AP Pelvis)
Is dome attached to ilium?
- No = ABC
- Yes = Is obturator ring Intact?
- Yes = Transverse
- No = Is Anterior column segmental?
- Yes = Ant Column + Post Hemi-transverse
- No = T-Type
How do you differentiate an anterior wall from an anterior column fracture on radiographs?
[Rockwood and Green 8th ed. 2015]
- Anterior wall has 2 breaks in the iliopectineal line
* Anterior column has 1 or none - Anterior column has a break in the ischiopubic ramus
* Anterior wall does not
What are the 3 classifications of anterior column fractures?
[Rockwood and Green 8th ed. 2015]
- High = fracture exits iliac crest
- Intermediate = fracture exits ASIS
- Low = fracture exits below AIIS
What are the 3 types of transverse acetabular fractures ?
[Rockwood and Green 8th ed. 2015]
- Transtectal
- Cross the weightbearing dome of the acetabulum
- More vertical fracture compared to infratectal and has less articular surface remaining
- Juxtatectal
* Cross the articular surface at the level of the top of the cotyloid fossa - Infratectal
* Cross the cotyloid fossa
What is the ‘gull wing sign’ in acetabular fractures?
[Rockwood and Green 8th ed. 2015]
Impaction of the medial acetabulum roof
- Occurs with anterior and posterior hemitransverse or isolated anterior column fractures
- Presence of this impaction is a poor prognostic sign
***Easily confused with “Gull sign”
- Initially described Letournel and Judet for variations of posterior column fractures where the posterior column displaces and takes the hind portion of acetabular roof
- Therefore the posterior segment loses its normal relationship with the segment still attached to anterior column and forms “an image like a gull in flight”
The ‘spur sign’ is pathognomonic for what fracture type?
[Rockwood and Green 8th ed. 2015]
Associated both column
- Best seen on the obturator oblique view
- Represents the intact iliac fragment
- Represents the external cortex of the most caudal portion of the intact ilium
How much fracture displacement involving the superior acetabular dome (WB surface) is acceptable to consider nonoperative management?
[Rockwood and Green 8th ed. 2015]
<2mm
What are the ‘roof arc measurements’ described be Matta and what are their significance?
[Rockwood and Green 8th ed. 2015]
- A vertical line is drawn through the centre of the femoral head
* Second line is drawn from the centre of the femoral head to the fracture location on the acetabular articular surface - The measurement is made on 3 views
- Medial roof arc measured on AP
- Anterior roof arc measured on obturator oblique
- Posterior roof arc measured on iliac oblique
- Significance
* Determines if the intact acetabulum is sufficient to maintain a stable and congruous relationship with the femoral head - Nonoperative treatment indicated if: [Vrahas et al JBJS 1999]
- Medial RAM > 45°
- Anterior RAM > 25°
- Posterior RAM > 70°
- ***Initial cutoff was 45 for medial, anterior and posterior
*** NOTE: not applicable to both column and posterior wall fractures
What is ‘secondary congruence’ in both column fractures?
[Rockwood and Green 8th ed. 2015]
- Describes congruency between the femoral head and the displaced acetabular articular surface without skeletal traction applied
* Parallelism between femoral head and acetabular articular surface must be seen on all three views - If present can treat nonop
* Unless hip motion will be limited or limb will be unacceptably shortened