mechanism

Vertical Shear

Vertical shear

 

Definition

 

Unstable injuries

Complete disruption of both the anterior and posterior ring

 

5 - 20% of pelvic fractures

 

Mechanism

 

Axial load

Motor vehicle accident

Fall from height

 

Pathology

 

Anterior ring

Internal snapping hip

Cause

 

Movement of iliopsoas tendon over femoral head / iliofemoral ridge / iliofemoral ligament

 

Symptoms

 

Audible or palpable snap in the groin

Hip moves from flexed / abducted / externally rotated position to extended / internally rotated position

 

Incidence

 

10% of the population - usually painless

 

Examination

 

Move hip from flexed / abducted / externally rotated position to extended / internally rotated position

Cuboid Fractures

Types

 

1.  Capsular avulsions

 

2.  Body / Nutcracker fracture

 

Nutcracker fracture

 

Epidemiology

- rare

 

Mechanism

- forced eversion / abduction of forefoot

- cuboid crushed between 4th and 5th MT and calaneum

 

Pathology

- displaced cuboid fracture with subluxation of tarsus

Hoffa fracture

Definition

Hoffa Fracture Xray

 

Coronal plane fracture of distal femoral condyle

- intra-articular

- often only attachment is posterior capsule

 

Epidemiology

 

Rare

 

Mechanism

 

Usually a severe valgus trauma

 

Xray

 

Central Cord Syndrome

Epidemiology

 

Most common pattern cord injury

 

Hyper-extension injury in middle aged man with osteoarthritic spine

 

Usually C3/4 and C4/5

 

Mechanism

 

Most common type / in older patient with pre-existing spondylosis / OPLL

- hyperextension injury

- compression of the cord

- anteriorly by osteophytes

- posteriorly by infolded ligamentum flavum

 

DIC

Definition

 

Disseminated Intravascular Coagulation

 

Pathology

 

Results from excessive activation of either extrinsic or intrinsic coagulation pathway

- multiple small clots 

- consumptive coagulopathy

 

1.  Excessive Extrinsic Activation

 

Secondary to extensive cellular destruction

- thromboplastins +++ released into circulation

Sacral Fractures

Mechanism

 

High energy usually

 

Occasionally osteoporotic fracture in elderly

 

Other

- radiotherapy

- fatigue fracture in children

 

Don't present as isolated injury

- associated with pelvic fracture

 

Denis Classification

 

Zone 1

- lateral to foramina

- neurologic injury from proximal migration & compression of L5 nerve root

Spinal Cord Concussion

Definition

 

Transient disturbance of spinal cord function

- +/- vertebral column injury

- no pathological changes in spinal cord

 

Mechanism

 

Rapid change in velocity following trauma

- football / ice hockey

 

Associations

 

Congenitally narrow spinal cord

Hypermobility

 

Radiotherapy

Definition

 

Use of ionising radiation to damage DNA to prevent cell replication

 

Mechanism

 

Most rapidly replicating cells affected the most

 

Radiosensitive tissue

- high turnover tissue

- high blood supply

 

Give DXRT in incremental radiation

 

Produce free radical by breakup of H2O

- H2O -> H+ + OH-

- free radicals denature DNA