mechanism

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

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

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

Definition

Coronal plane fracture of distal femoral condyle

- intra-articular

- often only attachment is posterior capsule

Epidemiology

Rare

Mechanism

Usually a severe valgus trauma

Xray

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

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

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

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

Mechanism

Direct blow

- most common

Indirect

- forced knee flexion with foot fixed / maximally contracted quadriceps

Types

1.  Vertical

2.  Transverse

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