Pelvis and Lower Limb Trauma Flashcards
Explain the polo mint theory
It applies to the pelvic ring
(the pelvic ring is formed by the sacrum, ilium, ischium & pubic bones)
If the pelvic ring is disrupted in one place, there is invariably a further disruption elsewhere in the ring
What are the 3 main patterns of injury that occur in the pelvis?
- A lateral compression fracture
- A vertical shear fracture
- An anteroposterior compression injury
Discuss lateral compression fractures of the pelvic ring
- occurs with a side impact
- one half of the pelvis is displaced medially
- fractures through the pubic rami or ischium are accompanied by a sacral compression fracture or SI joint disruption
Discuss vertical shear fractures of the pelvic ring
- occurs due to axial force on one hemipelvis where the affected hemipelvis is displaced superiorly
- sacral nerve roots and lumbosacral plexus are at high risk of injury and major haemorrhage may occur
- the leg on the affeced side will appear shorter
Discuss anteroposterior compression injury
- may result in wide disruption of the pubic symphysis, the pelvis opening up like the pages of a book: “open book pelvic fracture”
- substantial bleeding from torn vessels occurs and as the pelvic volume increases exponentially with the degree of displacement
- with widely displaced injury the pelvis can contain several litres of blood (i.e. the entire circulating volume) before tamponade and clotting will occur
We know that pelvic injuries are usually high energy and so involve other systems. What systems might this include?
Bladder and urethral injuries (blood at the urethral meatus) may also occur and urinary catheterisation may risk further injury!
Urological assessment and intervention may be required.
What exam MUST you do to a patient presenting with a pelvic fracture?
A PR exam is mandatory to assess sacral nerve root function and to look for the presence of blood.
Why is it important to do a PR exam in someone presenting with a pelvis injury?
Blood on a PR exam would indicate a rectal tear rendering the injury an open fracture and carries a higher risk of mortality.
An elderly patient presents with a low energy pubic rami fracture. What type of fracture is it likely to be?
Tends to be minimally displaced lateral compression injuries (with sacral fracture or SI joint disruption posteriorly) and settle with conservative management over time.
A car driver’s knees collide with the dashboard in a RTA. What injury might they have?
Posterior wall fractures of the acetabulum may be associated with a hip dislocation.
In these cases, the posterior wall of the acetabulum is fractured as the head of the femur is pushed out the back of the joint.
What imaging investigation is most appropriate for suspected acetabulum fractures?
CT Scan
The pattern of the fracture can be difficult to determine on plain X-Rays (oblique views may help) and CT scans help to determine the pattern of the fracture and are essential for surgical planning.
Non-operative management of hip fracture is just as risky as operative management
T/F
Yes
Almost all hip fractures undergo surgery within the first 24 hours unless time is required for medical optimisation
Describe the arterial supply of the femoral head
comes from a ring anastomosis of the circumflex femoral arteries at the insertion of the hip capsule at the base of the femoral neck
The medial and lateral circumflex femoral arteries are branches of the profunda femoral artery
Arteries from the ring anastomosis travel up the femoral neck and into the femoral head
For which patients are hemi-arthroplasties more appropriate than a total hip replacement?
those with restricted mobility and the cognitively impaired
Extra-capsular hip fractures are more associated with AVN than intra-capsular hip fractures
T/F
FALSE
Extracapsular hip fractures should not cause AVN and have a high union rate
What is the typical surgical management of an extra-capsular hip fracture?
Internal fixation, keeping the patient’s own natural hip joint. Either:
- compression
- dynamic hip screw
Which patient and MoI is most common in subtrochanteric hip fractures?
Usually occur in elderly patient with osteoporosis & fall onto the side
If a femoral shaft fracture hasn’t occurred as a high energy injury, what risk factors might the patient have that contributed to this injury?
- osteoporosis
- metastatic disease
- Paget’s disease
- paradoxically long term bisphosphonate use for osteoporosis
(in terms of stablisation) what are the roles of the medial and lateral collateral ligaments?
resist valgus and varus stresses respectively
(in terms of stablisation) what are the roles of ACL and PCL?
stabilise the tibia in the sagittal and rotational planes
What position is usually adopted by those with a distal femoral fracture?
Flexed position due to the pull of the gastrocnemii muscles
Is a knee dislocation a surgical emergency?
A knee dislocation is a surgical emergency with a high incidence of vascular injury (intimal tears, vascular occlusion, complete transection), nerve injury and compartment syndrome
What way does the patella usually dislocate?
Laterally
due either to a direct blow or a contraction of the quadriceps with a rotational force with the patella not engaged in the trochlea
What are tibial plataeu fractures?
They are intra-articular fractures with either:
- a split in the bone,
- a depression of the articular surface
- or a combination of both.
A patient presents with a valgus stress injury to the knee. Waht do you think has happened?
(there may be)
a lateral plataeu fracture with a failure of the MCL and possibly ACL with increasing force
A patient sustained a direct blow from a car bumper as they were using the zebra crossing.
What injury might they have sustained?
Proximal fibular fracture and injury to the common peroneal nerve with foot-drop
A patient presents with a varus injury.
What do you think may have happened?
Medial plateau fracture (less common than lateral i think?) with potential for LCL rupture and stretch injury to the common peroneal nerve
Which fractures are the commonest cause of compartment syndrome after trauma?
Tibial shaft fractuers
(esp. anterior compartment of the leg)
What is a “pilon” fracture?
Intra-articular fractures of the distal tibia are termed “pilon” fractures.
They generally require ORIF to ensure a congruent articular surface.
What movements are most ankle injuries caused by?
An inversion injury
and/or rotational force on a planted foot
How might a sprain of ankle ligaments present?
And which ligaments are likely to be sprained?
- pain
- bruising
- mild to moderate tenderness over involed ligaments
Sprains of the lateral ankle ligaments (anterior & posterior talofibular ligaments and calcaneofibular ligament) are commonplace
What criteria is used to identify suspected ankle fracture and give guidance as to which ankle injuries require an X-Ray?
the Ottawa criteria
What merits an X-Ray with a suspected ankle fracture?
Bony tenderness of the distal tibia or fibula
or inability to weight bear for four steps
