Chapter 36- Injuries to the pelvis and acetabulum Flashcards
What are the two major functions of the pelvis
- Transmits load (body weight mostly) during sitting and walking
- It provided an anchor for muscles acting on the trunk above and the lower limbs below
Which major blood vessels lie on the inner wall of the pelvis or in close relation to the pelvis
- Internal iliac
- Superior and inferior gluteal
- External iliac
Which organs are at risk with major pelvic disruptions?
- Bladder
- Ureters and urethra
- Rectum
- Bowel
- Vagina
What are the types of stable injuries to the pelvis
- No break in the ring: caused by direct force of avulsion of muscle attachment
- Break in the ring: Usually pubic rami fractures. Always look carefully to exclude a disruption in another part of the ring
Describe the Young and Burgess classification of unstable injuries to the pelvis- list from most stable to least unstable.
- AP compression: Disruption of symphysis by a AP directed force. If associated with opening of the sacro-iliac ligaments = open book fracture
- Lateral compression fracture: lateral force may fracture sacrum, iliac wing or pubic rami (Ramus fracture may cause bladder perforation)
- Vertical shear fracture: High impact loading force on one leg –> one hemi-pelvis is sheared off and displaced vertically. Clue to the injury is fracture of L5 transverse process
what should one exclude in pelvic injuries resulting from minor or low energy injuries?
-Exclude bone abnormalities causing weakness such as a metabolic bone disorder (osteopaenia, Paget’s) or neoplasm (usually secondary)
What is the order or priority on examination in a pelvic injury
- Breathing, bleeding, belly, bowel, bladder, bone
Why is it important to check for any skin lacerations on the perineum?
-May be a need for defunctioning colostomy
Why should applying pressure on the pubic symphysis only be performed once
Repeat examinations may lead to dislodging of formed clots
What does it imply if lacerations are found on PR examinations?
Potential contamination of pelvic fracture by bowel flora
What is the implication of a limb with a feeble or absent pulse and neural loss?
-May be closed hindquarter avulsion or amputation. It is a life threatening emergency and an urgent hindquarter amputation is necessary to remove the dead limb
What Xrays are done first in suspected pelvic injury? What views are then requested on secondary survey?
- An AP xray is done first
- If fracture identified on the AP view, then inlet and outlet views are obtained during secondary survey
What direction of displacement do the inlet and outlet views of the pelvis show?
- Inlet: displacement in the AP plane
- Outlet: Displacement in the longitudinal plane
Which fractures of the pelvis is a CT scan the most sensitive modality for
- Posterior ring injuries and their degree of displacement
- Four fractures are seen in specific anatomic regions: sacro-iliac dislocations, sacral fractures, iliac wing fractures, sacro-iliac fracture dislocations
What are the prime goals in the acute management of pelvic injuries
Haemodynamic stability and skeletal stability
What are the main causes of bleeding within the pelvis following a pelvic injury
-Bleeding is usually from fracture surfaces and venous plexuses (arterial bleeding is less common)
How is skeletal stabilisation achieved in the resuscitative management of a pelvic injury?
- Application of a pelvic binder or a sheet around the pelvis
- External fixators are used in unstable open fractures
What are the benefits of using a pelvic binder/ sheet around the pelvis in the initial managment of a pelvic injury
- benefits patients by decreasing the pelvic volume and effecting tamponade
- Highly effective in open book fractures
- Can be rapidly applied without the need to transfer the patient to theatre
- no orthopaedic expertise is required
- Inexpensive
What is the initial, acute management of open pelvic fractures
- ATT ?
- Initial wound care
- ?Colostomy
- ?Ext fixator
If patients have arterial bleeding following a pelvic injury, what are the 2 most likely sources? what is the treatment for each?
- Large named vessels eg iliac or femoral arteries- Often die at the scene or require massive blood transfusions, surgical intervention may also be required
- Smaller named arteries eg superior gluteal - angiography and embolisation of the vessels are usually required
Definitive management of avulsion fractures
- Symptomatic pain relief by medication
- Rest if necessary
- Return to activity as pain allows
Where do avulsion fractures of the pelvis usually occur
These occur at sites of muscle attachment. In children this will be an apophyseal separation
eg. Ant. sup iliac spine: sartorius
Ischial tuberosity: hamstring
Definitive management of iliac blade fractures
Bed rest and analgesia
ORIF indicated if grossly displaced
Definitive management of sacral fractures
- May have associated sacral nerve root injury
- Treat conservatively if undisplaced
- ORIF or percutaneous fixation if displaced
Definitive management of pubic rami fractures
symptomatic: analgesia and bed rest until pain settles
mobilise with support when pain permits
Definitive management of open book fracture
- Apply binder initially
- Conservative management if diastasis is less than 2.5 cm
- ORIF with plate and screws if diastasis is more than 2.5 cm
definitive management of lateral compression fractures?
ORIF is indicated in displaced and/or unstable fractures
Definitive management of vertical shear fracture
Reduce by application of skeletal traction to the affected limb
ORIF is preferred to allow early mobilisation
-ORIF undertaken once patients are haemodynamically stable and fit for anaesthesia
- Thrombo-prophylaxis as soon as patients haemodynamically stable
What are the advantages of minimally invasive percutaneous surgery for injuries to the pelvis
- Less soft tissue disruption
- less bleeding and no disruption of the pelvic haematoma
- Shorter surgical time
- Reduced exposure related hazards
What are the long term complications of pelvic injuries
- Pain
- leg length discrepancy (malunited vertical shear fractures)
- Pelvic obliquity with sitting difficulty
- None union (rare)
- Dyspareunia - unreduced spike of ramus fractures
- nerve damage - injury related or iatrogenic during surgery
What are the two groups that make up a majority of acetabular fracture patients
- High energy trauma in young, active patients and these are frequently polytrauma victims
- Elderly patients with poor bone stock who frequently present with complex fracture patterns
Why is the treatment of acetabular fractures such a challenge?
- Irreversible damage to the articular surface
- Comprehension of fracture patterns requires detailed understanding of 3D patho-anatomy
- Difficult surgical access
- Prolonged rehabilitation
- Significant potential post-operative complications
What factors affect the fracture pattern of acetabular fractures?
- position of the femoral head at time of injury
- Magnitude of the force
- Age of the patient
Why is careful assessment of the neurovascular status necessary in fractures of the acetabulum?
- Sciatic nerve injury may be present in up to 40 percent of posterior column disruptions
- Femoral artery may be compromised by anterior column injury
- Fracture displacement into the sciatic notch can cause injury to the superior gluteal artery (diagnosed and treated with angiography and embolisation)
What views are necessary for the radiographic examination of the acetabulum?
AP and judet views (iliac and obturator obliques)
What are the anatomic landmarks in the AP view of the acetabulum?
- iliopectineal line
- ilioiscial line (corresponds to posterior column)
- The U composed laterally of the most inferior and anterior portion of the acetabulum and medially of anterior flat part of quadrilateral surface of the iliac bone
- dome of acetabulum
- Edge of anterior wall
- Edge of posterior wall
What do the judet views of the acetabulum help visualise?
- Obturator oblique demonstrates the obturator ring, posterior wall and the lower portion of the anterior column. Best view to observe the spur sign
- Iliac oblique demonstrates the iliac wing, greater sciatic notch, posterior column and edge of the anterior wall
What information does a CT scan provide in fractures of the acetabulum
- Fracture pattern assessed in more detail
- More information regarding comminution, marginal impaction (in wall fractures), retained bone fragments in the joint and sacro-iliac joint disruption
- 3D reconstruction allows for digital subtraction of the femoral head –> full delineation of the acetabular surface
Acetabular fractures are frequently associated with dislocation, what is a dislocated femoral head more susceptible to?
- Cartilage damage at time of dislocation
- Point loading with displaced fractures
- Avascular necrosis
How is an acetabular fracture reduced?
Patient placed in skeletal or skin traction to allow for initial soft tissue healing, allow associated injuries to be addressed, maintain the length of a limb and maintain femoral head reduction within the acetabulum
When is a fine cut CT scan indicated in the initial management of an acetabular fracture?
If there is incongruent reduction on the AP pelvis Xray ot the patient is being considered for operative management
(Rules of intra-articular fragments)
What are indications for non-operative management of acetabular fractures?
- undisplaced and minimally displaced (<3 mm) fractures
- Congruent both column fractures
- Wall fractures with sufficient intact wall to maintain hip stability
- Displaced column fractures that only involve the inferior part of the acetabulum
- Co-morbidities limiting physiological reserve
- Insufficient bone stock to allow adequate fixation
- Local soft tissue problems such as infection and wounds
- Presence of suprapubic catheter is a contraindication to surgical treatment by the ilio-inguinal approach
What is the non-operative management of acetabular fractures?
-Patient kept non-weight bearing for 4- 8 weeks. Skeletal or skin traction may be appropriate to prevent further displacement
What is the operative management of acetabular fractures?
ORIF is the treatment of choice
Prophylactic antibiotics are mandatory pre-operatively
When is urgent ORIF indicated for an acetabular fracture?
- Reduction of an associated dislocation of femoral head cannot be maintained
- Retained intra-articular fragments
- Closed reduction not possible
- Closed reduction has resulted in new onset neurological deficit
- Open fracture
When is an ORIF not indicated in acetabular fracture and what is the alternative operative management?
- ORIF is not indicated in elderly patients, especially if there is evidence of impaction or osteoporosis
- Limited reconstruction and total hip replacement may be considered
- Total hip replacement in acute setting may be associated with complications eg dislocation
What are complications of a fracture of the acetabulum?
- Surgical and wound infections (higher with abdominal and pelvic visceral injuries)
- Heterotrophic ossification (indomethacin and low dose radiation to prevent)
- Avascular necrosis
- Chondrolysis
- Nerve injury (Sciatic, femoral, superior gluteal nerves)
- Vascular injury (femoral artery)
- Thromboembolic complications
- Intra-articular screw penetration
- Failure of fixation
- non-union
What fractures are associated with hip dislocation
Posterior or anterior wall fractures
What is the mechanism of injury in a posterior hip dislocation?
-Axial load transmitted up the femur to the hip joint, which is in flexion (eg. dashboard injury in MVA)
What are the examination findings in posterior hip dislocation?
-Leg lies in internal rotation, adducted, slightly flexed and is shorter than uninjured limb
What associated injuries should you look for on examination of posterior hip dislocation?
- Patellar fracture (if direct force)
- Sciatic nerve impairment- common peroneal nerve component especially
- In a driver: associated fracture and/or dislocation of the foot bones
Findings on AP Xray of a posterior hip dislocation
- Acetabulum may appear empty
- Femoral head lies above the acetabulum
- Shenton’s line broken
- Femur adducted
- Lesser trochanter small or not visible because it is internally rotated
Treatment of posterior hip dislocation
- Urgent reduction under GA with muscle relaxant
- Place patient on floor
- Assistant graps iliac blades from above and holds the pelvis firmly down
- Apply traction in the line of the deformity until the hip is flexed to +- 90 degrees and in adduction
- Reduction will be evidenced by audible clonk
- Obtain post-reduction Xray to confirm reduction
- CT scan must be done in a fracture dislocation to exclude loose bone fragment. If present, should be removed as soon as possible
What is the mechanism of injury in Anterior dislocation of the hip
Forced abduction of the leg
occurs in motorcyclists and horseriders
Examination findings of anterior dislocation of the hip?
- Leg lies in abduction, external rotation and flexion
- Femoral head may be palpable in inguinal region
Findings on AP Xray of an anterior hip dislocation
- Empty acetabulum
- Broken Shenton’s line
- Prominent lesser trochanter
- Abducted femur
Treatment of anterior hip dislocation
- Reduce urgently because of femoral vessel and nerve compression
- Manipulate under GA
- Apply axial femoral traction with internal rotation and then adduct as the head reduces
- Lateral traction with folded towel or sheet may be helpful
- Post-reduction: Obtain Xray and CT scan, bed rest with skin traction until pain settles
- Mobilise with crutches partial weight bearing
Complications of hip dislocations
- Nerve palsy: peroneal component of sciatic nerve in posterior dislocation and the femoral nerve in anterior dislocation
- Avascular necrosis of the femoral head: occurs with delayed reduction (aim for reduction within 6- 8 hours of dislocation)
- Osteoarthritis: due to damage to the articular cartilage, especially when it involves a weight-bearing area.
