pins and wires Flashcards
Indications for Surgical Fracture Repair (Internal Fixation)
- Open fractures
- Fractures of the humerus, femur and some fractures of the pelvis, scapula, vertebral column, and skull
- Articular fractures
- Many oblique or comminuted fractures
- Avulsion fractures
Forces Neutralized by intramedullary Pinning
-intramedullary pins run right down the medulla of the bone
IM pinning rules
- Use a pin with a diameter 60-80% of the medullary canal at its narrowest point (unless combining with External skeletal fixation or plating, in which case diameter can be 30-50%)
- Spear the pin into the cortex at the other end of the bone (but do not penetrate this cortex!)
-Avoid threaded intramedullary pins.
They don’t prevent migration, and they
break.
- Anatomic fracture repair is required
bone which IM placement is good for
- Pin migration or bad placement can damage adjacent joints or soft
tissues - You need a nonarticular projection at one end of the bone to allow introduction or exit of your IM pin, if not then the pin will be invading the joint.
- Can be used for humeral, femoral, tibial, olecranon, calcaneal fractures, can use on bones which have “ends” nonarticular projections
- NOT good for radial fractures, has joints at both ends so no good place for pin to enter
cross pins placement and where are they used? what forces?
- Cross pins are short and do not control bending well
- Cross pin use is limited to
metaphyseal and physeal
fractures, where the adjacent joint will bend instead of the repair
Pin and tension band fixation when is it used?
Cerclage Wiring
(= circumferential wiring) uses? what forces?
- Helps control torsion and
compression that causes shearing - Minimal bending control
- Don’t use it alone!
Principles of Cerclage
- Cerclage wires must be
perpendicular to the bone, and they
must be tight - You must reconstruct the
cylinder of the bone…no gaps,
and no mushing. perfect O
-when the length of the fracture is 2x as long in a long oblique fracture. doesnt work in a short oblique fracture.
interlocking nails how they work
-Anatomic reconstruction of the fracture is not necessary with interlocking nail repair
Limitations of Interlocking Nails/ when they are used?
- Can be placed only in femur,
humerus, tibia - For repair of diaphyseal fractures
rather than fractures near bone
ends
external skeletal fixation ESF
- Transversely oriented pins connect the bone to a framework outside of the
limb - Controls all of the forces that act on a fracture, providing you choose a
strong enough configuration
transfixation pin types
-threaded pins are used most as they help the pin stay in place in the bone and not move
-there is a weak point at the interface of negative so make sure inside the bone
-no weak point in positive profile pins
rod and clamp system advantages
- Uniformly strong
- Bone is stabilized once you have the framework built
- Construct is adjustable if you don’t like the positioning of something
Rod-and Clamp System Disadvantages
- Pins have to be placed (more or less) in a straight line
- Limited angling possible
- Pins must be of similar size
Advantages of Acrylic and Thermoplastic
Connecting Bars
- Pins don’t have to be in a straight line
- Pin sizes can vary
- Many freeform configurations
possible - Cheap!
Disadvantages of Acrylic/Thermoplastic
Connecting Bars
- Fracture is not stable until connecting bar has set up; alignment must be held manually while this happens
- Not easily adjustable once connecting bar has set
IM pin- ESF tie in
- Good axial alignment of bone
- Good bending control with fewer
transfixation pins - IM pin can’t migrate
- Stronger than pin combined with
fixator but not tied in - Can only be used in bones appropriate for IM pinning (femur, tibia, humerus, a few etceteras)
transfixation cast
-common in people and LA
-cast provides bending and torsional control so you immobilize the joint above without having it be a long cast.
ESF transfixation pins rules
- Minimum of three pins per major fragment
- Fewer pins per fragment acceptable if ESF is tied in to IM pin (then a minimum of 1 pin per major fragment)
- Pins should not exceed 25% the diameter of the bone at that point
- All pins must fully penetrate both
cortices of the bone
Placement of Transfixation Pins
ESF connecting bar rules
- The closer the bar is to the bone, the
stronger the fixator…BUT - Clamps and rods too close to the skin
will cause nasty rub sores - Solution: place clamps/bars a finger’s
width away from the skin
ESF Postoperative Care
- Pins are placed through stab
incisions - It takes about 5 days for
granulation tissue to form in pin
tracks - Until that time, (Cover) with sterile gauze/fluff on soft tissues
between pins until day 5 then remove - After that, leave pin tracks open to
air; pad connecting bars
Advantages of ESF
- Minimal disruption of blood
supply to bone
-can remove hardware without GA when fracture is healed, removal can be staged to gradually transfer weightbearing forces back to the bone.
- Anatomic reconstruction of bone is
not necessary - Generally, ESF is the strongest
method for fixing tibial fractures - Good for fractures with relatively short
proximal or distal fragments - Joints can be spanned if necessary
- Relatively inexpensive setup
limitations of ESF
- Limited applicability for bones
with lots of muscle mass (femur,
humerus, ilium) - Some owner vigilance required
- Less familiar system for many
vets - Hardware does need to be
removed eventually
