Unit 6B - Surgical Fracture Fixation Flashcards
What is the most commonly used material in fracture fixation?
Stainless steel
What are the 3 parts of a screw?
Head
Shaft
Tip
What 3 factors determine the strength of a screw fixation?
- Strength of screw
- Strength of bone
- Design of screw thread
What are the functions of the head of a screw?
- Provides a butters to stop the hold screw sinking into the bone
- Provides a connection with the screwdriver
Name 3 type sof screw head shapes?
- Hexagonal
- Crosshead
- Star
Name the 3 different screw diameters to consider?
- Core diameter
- Shaft diameter
- Thread diameter
What is the pitch of a screw?
The linear distance travelled by the screw for a compete turn of the screw
Why are cortical screws not self-tapping?
Self tapping would cause damage to the bone and make screw impossible to insert due to excessive torque required
In engineering process of compressing two objects together is sometimes called what?
Lagging
Name 5 applications of orthopaedic screws?
- To prevent sideways displacement of fragments
- To hold a plate against bone
- To increase the grip of an intramedullary nail one the bone
- To permit displacement in an axial direction
- As part of an external fixator assembly
What is osteosynthesis?
Reconstruction of a fractured bone by surgical and mechanical means
When is the use of plates indicated?
- When anatomical alignment must be restored accurately
- Where the use of screws alone is inadequate
- When load sharing may be achieved with confidence
Name 4 areas of the body where plates are commonly used?
- Around joints
- In bones of the forearm
- On the pelvis
- On the face and jaw
What is the primary function of K-wires?
To maintain fragments in alignment by pushing them or holding them together
Flexible wire is used to induce compression in which 2 ways?
- Used statically by enclosing or crossing the fragments (clerage)
- Used dynamically as a tension band
Why is wire fixation becoming less popular than it used to be?
Due to it being awkward to use and because nails and screws can offer easier options
What is a cerclage wire?
A wire that crosses or encircles a fracture fragment
In which bones are pins commonly used in fracture fixation?
Small bones and upper limb bones in small children
Modern nailing is a technique whereby the nail is inserted into the bone from one end whilst not disturbing the fracture site at all - what is this called?
Antegrade technique
What are the 3 most important factors that determine the effectiveness of a nail?
- Material of which it is made
- How much of the nail is in contact with the bone for any particular fracture
- The dimensions and shape of the nail, and its wall thickness if it is hollow
Name 5 uses of intramedullary nails?
- Transverse and short oblique fractures of the trial and femoral shafts
- Comminuted fractures of tibia and femur, provided cross looking capabilities are available
- Pathological shaft fractures, especially in osteoporotic bone
- Delayed or non-union fractures of the shafts of the femur or tibia
- Selected open fractures
What are the main functions of cross screws?
- Hold apart bone fragments
2. Provide rotatory control
Name 5 uses of external fixation in orthopaedics?
- Limb lengthening
- Limb shortening
- Joint fusion (arthrodesis)
- Correction of angulatory or rotatory deformity
- Bone segment transportation
Name 2 uses of external fixation post-trama?
- Temporary
2. Definitive
What is dynamisation of an external fixator?
Release of a fixator to allow axial (proximal-distal) movements
What are the 2 principles for external fixator configuration?
- The bone/frame construct should be stable (i.e. not rigid)
- Pin placement must not tether soft tissue or restrict access to wounds
When is dynamisation usually used?
- The soft tissues are well on the way to healing
2. The simple unilateral frame is to be used for definitive fracture control
What are the advantages of using external fixators?
- Can be assembled and fitted quickly which is of value in emergencies
- They can be adjusted at a later time
- Can remove beam of the fixator to take clear x-rays
- Fixators are versatile enough to use in many sites
- Excellent access to soft tissues
What are the 3 main disadvantages of external fixators?
- Infection of bone-pin interface
- Pin loosening if weight bearing is applied
- Soft tissue tethering by pins between skin and bone
Name 3 complications of external fixation?
Pins may loosen
Pin tract infection
Soft tissue tethering
