Pelvis Flashcards
Discuss contributors to the stability of the pelvic ring
Anteriorly the symphysis pubis provides the major mechanical stability.
Posteriorly a composite of strong ligaments - the sacrospinous, sacrotuberous, iliolumber and anterior and posterior sacroiliac ligmanets maintain the integrity of the arch
Discuss Tile Classification of pelvic fractures
Type A: stable posterior arch intact; includes avulsions fractures, isolated iliac wing fracture, pubic rami fractures, minimally displaced ring fracture and transverse fracturs of the sacrum or coccyx
Type B: partially stable - incomplete disruption of the posterior arch incudes
- AP injuries: open book
- Lateral compression - may be unilateral or bilateral these injuries are rotationally unstable but vertically stable
Type C: unstable complete disruption of the posterior arch
-iliac and sacroiliac fractures and vertical sacral injuries that result from vertical shearing forces; may be unilateral or bilateral. These are both rotational and vertically stable
Discuss Young- Burgess calssification of pelvic fractures
AP compression
1) Symphasis diastasis <2.5cm
2) symphasis diastasis >2.5 cm - sacrospinous and anteiror sacroiliac disruption results in rotational instability
3) Symphasis diastasis >2.5 cm with complete disruption of the anterior and posterior sacroiliac ligament results in complete rotational and vertical instability
Lateral compression
1) sacral crush injury on ipsilateral side
2) sacral crush injury with disruption of posterior SI ligaments, iliac wing fracture may be present - rotationally unstable
3) Severe internal rotation of ipsilateral hemipelvis with external rotation of contralateral side (windswept pevlis) - rotationally unstable
- Contralatearl AP compression
Vertical shear
-vertical displacement of symphysis and CI joint resulting in complete rotational and vertical instbaility
Combined
Discuss stable pelvic fractures
The normal pelvis is not totally rigid because of the slight mobility at the SI joints. - A single break through the pelvic ring is generally considered stable.
Describe straddle fracutre
A four pillar injury involving fractures of both pubic rami on both sides of the symphysis pubis creating a buttfly segment.
Although these fracture can occur without posterior arch disruption four pillar injuries are commonly associatred with lateral compression or vertical sheer forces and evaluation for other injuries is required
High risk of associated injuries
-urological
Discuss transverse fractures of the sacrum
Not unstable
below the level of S4 unlikely to cause neurological deficit
Discuss AP compression fracture
Severe AP forces cause disruption at or near the symphysis pubis.
Symphysis widening of less than 2.5cm is considered a stable injury
With further force in the AP direction the hemipelvis externally rotates tearing the sacrospinous, sacrotuberous, and the anterior sacroiliac ligaments.
The SI joint opens and hinges on the intact posteior SI ligament. Rotationally unstable but veritcally stable due to intact posterior SI ligament
If diastisis is greater than 2.5cm the risk of complete disruption of the ligaments or vertical shear fracutres are high
The same force can also injury the neurological and vascualr structures of the posterior arch - these also increase the overall volume fo the pelvis facilitating the expansion of a retroperitoneal haematoma.
Discuss lateral compressions fractures
Lateral compression of the pelvis results in varying degrees of internal rotation of the affected hemipelvis.
THis initially causes buckling of the sacrum and horizontal pubic rami fractures.
As force increases the symphysis can be disruptued causing overlapping of the pubic bones.
Similar to AP as the disruption of the posteiror ligaments increases so does the lateral instability - AS force increase the contralateral side may extenral rotate leading to the windswept pevis
Vertical stabilty intact
Reduces space in the pelvis less risk of exanguantion into the pelvic rim
Discuss veritcal shear injury
Most unstable injuries and are associated with violent axial loading of the hemipelvis that causwe fractures in vertical planes.
anteriorly the symphysis and rami can be disrupture and posteirorly dross displacement and instability in the rotational and vertical planes may eb present through the sacrum, the SI joint or the ilium such that the hemipelvis is displaced posteriorly and cephalad.
Vertical sheer energy is also transmited throught the rich vascular network and nerve plexus directly adjacent to the bone.
Discuss vertical sacral fractures.
Vertical sacral fracture are caused by high energy injrues and do effect stability of the pelvic ring. They are classified by the Denis into
1) extending laterally to the sacral foramina
2) through the foramina
3) medially to the foraminia involve the central spinal canal
High risk of neurologic sequale increasing in risk as the grades increase
Discuss open pelvic fractures
Direct communication between the fracture site and a skin, rectal or vaginal wound. These are potentially lethal injuries especially if not recognized early.
Discuss associated pelvic injuries with pelvic fracture
urological
Bladder and urethral disruption.
Fractures of the anterior arch are the most common source of urological injuries
Gross haematurai indicates injury of the lower urinary tract. Bladder rupture is diagnosed in about 25% of patients with gross haematuria and pelvic fracture.
High riding prostate and blood at the meatus are signs of urethral inury and a retrograde urethrogram is mandatory prior to catheterisation
CT should be perfromed prior to retrograde urethrocystogram as it may interfere with the ability to identify extravasation of contrast
Sexual dysfunction is a recognised complications of pelvic trauma occuring in 44% of femals and 50% of males.
- Increases with instability of the pelvis
- Sacral fracrtures may lead to complete or incomplete caurda equina.
Discuss acetabular fractures
Broadly categorised into three types
A: 1) posterior wall fractures are the mose common acetbular injury and are generally caused by a forceful impact to a flexed knee. The force is transmitted up through the femur through the posterior acetabulum. An associated posterior hip dislocation is common. Hip dislocation is commonly asscoiated with sciatic nerve injury
2) anterior wall fractures are more commonly seen with extension of a superior ramus fracture.
B: Involve both anterior and posterior columns but a portion of the acetbaulum remains atached to the ilium
C: two column fracture with none of the articular surface remaining
Discuss IX of pelvic fracture
AP pelvis - insensitive, good if patient to unstable for CT, look at pubic symphasis diastasis
CT: best
US: not good at evaluation of retroperitoneal bleeding which is the most common place for pelvic bleeding
Disucss management of pelvic fracture
A- secure if needed
B:
C: Fluids resus 20ml/kg of crystaloid or straight to RBC resus TEG or ROTEM guided or 1:1:1
-two options
1) mechanical stabilization
-pelvic binder - most effective application site is the greater trochanters and symphysis pubis regions
- formal external fixation - should not be attempted if will dealy more definitive treatment of pelvic bleeding by angiography
2) angio + venography and embolisation
-although impossible to deliniate wether venous or arterial bleeding initially failure to respod to adequate resus ( failure to maintain systolic above 90 despite admin of 2 or more units of PRBC) or contrast extravasation are indicative of active arterial bleeding.
- posterior arch disruption should have early consideration
-Complications include gluteal muscle necrosis, surgical wound rbeakdown, infections impotence and bladder necrosis
