Pins and nails Flashcards
Which technique has become the principle way to hold long bones of the leg and to a lesser degree the humerus?
Intramedullary nails
What care must be taken when imaging intramedullary nail insertion?
Radiation dose that the surgeon is subjected to
What are pins also known as?
K-wires
Describe the design of a pin
Have sharp “trochar points” or occasionlly threaded, self tapping ends
How are pins inserted?
Driven into bone fragments by hand driven T-handles or on hand or even air powered drills
When are pins most commonly used?
In small bones (e.g. foot and hands)
Occassionally in upper limb long bones in small children
Why are pins generally used in pairs?
To minimise the rotatory element in the final pin/bone construct
When might pins be used in conjunction with flexible wire?
To achieve compression between 2 small bone surfaces (e.g. patella fracture)
What 2 ways is flexible wire used?
Cerclage (static)
Tension band 9dynamic)
How are flexible wires used as cerclage?
Encircles or crosses the fragments pushing them together (e.g. cracked long bone)
Why have nails replaced cerclage in most situations?
Do less damage to the blood supply if used properly
Are much more robust
Give an example of when cerclage is useful
Around cracked fragments of bone around endoprostheses - during hip reviison surgery sometimes deliberately crack femur to remove primary prosthesis - cerclage can be used to maintain a medullary cavity so that the new prosthesis can still be inserted
How do wires work as a tension band?
Utilises the power of surrounding muscles to produce compression at a fracture site (e.g. patellar, olecranon and medial malleolar fractures) - the more the muscles work the more stable the fracture will be
Why is tension banding a useful way of rehabilitating damaged joints?
Movement promotes stability and encourages joint nutrition and cartilage as well as bone recovery
Why when using cerclage wires is it important, where possible, to work beneath the periosteum?
To avoid damage to blood supply
Why are wires still used extensively in spinal surgery?
It can be threaded through restricted holes and its versatility can produce powerful fiation
What is the principal reason that wire has fallen out of routine use?
Its awkwardness is use and the need to twist it properly (over-twisting causes breakages)
Also surgeons find other techniques more elegant
How do intramedullary nails work?
Placed in the medullary canal and fucntion as a form of internal splint which stabilises long bone fractures with minimal damage to the surrounding soft tissues
What are the advantages of intramedullary nails?
Minimal damage to surrounding soft tissues
Uusally withstand axial and bending stresses
Can achieve rotatory control when combined with screws and playes
Can be mobilised early after surgery with weight bearing before bony union
What is the antegrade technique?
Nail is inserted into the bone from one end whilst not disturbing the fracture site ata all
What is essential when attempting antegrade technique?
X-ray image intensifier
What is the retrograde technique?
Fracture site is opened by soft tissue dissection and the fracture end delivered into the wound for reaming and insertion of the nail
What is reaming?
Widening of the intramedullary canalthrough paring off the inner surface of the bone
What are current developments in nail design centred around?
Whether to ream or use nails which are solid and thinner so they they can be inserted without damage to the inner blood supply
