Orthopedic fractures Flashcards
(34 cards)
Fracture reduction is the
process of either reconstructing fractured
bone fragments to their normal anatomic configuration or restoring normal limb alignment by reestablishing normal limb length and joint alignment while maintaining spatial orientation of the limb.
Closed reduction refers to
reducing fractures or aligning limbs without surgically exposing fractured bones.
Closed reduction enhances the biologic environment by
* preserving soft tissue and blood supply, which speeds healing
* decreasing risk of infection
* reducing operating time
Open reduction is
a surgical approach to expose fractured bone segments and fragments so that they can be anatomically reconstructed and held in position
with implants.
- “open but do not touch” reduction in which a lengthy exposure is made for realigning the bone and placing a plate but the fracture fragments and hematoma are not manipulated.
Advantages of open reduction: (4)
- visualization and direct contact with bone fragments can facilitate anatomic fracture reconstruction.
- direct placement of implants (e.g., cerclage wire, lag screws, and plates) is possible;
- bone reconstruction allows bone and implants to share loads, which results in stronger fracture fixation (i.e., improving the mechanical environment);
- cancellous bone grafts can be used to enhance bone healing
Disadvantages of open reduction: (4)
- increased surgical trauma to soft tissue and blood supply
- diminishing the biologic environment
- greater opportunity to introduce bacterial contamination
- increases the procedure/operation time
Indications for open reduction. (3)
- articular fractures
- simple fractures that can be anatomically reconstructed
- comminuted /fragmented nonreducible diaphyseal long bone fractures - use the “open, but do not touch” method
Indications for closed reduction. (2)
- greenstick and or nondisplaced fractures of long bones below the elbow of stifle
- fragmented nonreducible diaphyseal fractures of long bones treated with external fixators
Aims of osteosynthesis: (5)
¤ Repositioning of bone fragments
¤ Strong fixation
¤ Compression, ensuring constant contact of bone fragments
¤ Blood supply restoration in the fractured area (minimal damage of the surrounding soft tissues and faster regeneration)
¤ Restoration of the limb function
Methods of osteosynthesis (fracture fixation). (4)
¤ Intramedullary (IM) pins and cerclage wire
¤ Interlocking nails (ILNs)
¤ External skeletal fixators (ESFs)
¤ Bone plates and screws
Describe Intramedullary Fixation of bone fractures.
Intramedullary fixation is the method where bone
fragments are fixated with a construction that is placed inside a tubular bone, i.e. into medullary cavity.
Pins of different profile and length are used for fixation. The pins are inserted into the medullary cavity either through the fractured area or through the proximal or distal epiphyses.
The main principle of intramedullary fixation is to restore the axis of the fractured bone.
Intramedullary pins are used for diaphyseal (mid) fractures of the humerus, femur, tibia, ulna, and metacarpal and metatarsal bones.
Never place IM pins into the radius due to high likelihood of joint penetration into the carpus or articular surface of the radial head!
Never place IM pins into which long bone and why?
the radius due to high likelihood of joint penetration into the carpus or articular surface of the radial head!
The biomechanical advantage of IM pins is?
And disadvantage?
their resistance to applied bending loads.
Biomechanical disadvantages of IM pins include poor
resistance to axial (compressive) or rotational loads and lack of fixation (interlocking) with bone.
IM pins are
smooth, round, stainless steel rods.
The most common IM pins used in veterinary medicine
are Steinmann pins.
They can be single armed (one end with a point and one
end blunt) or double armed (a point at each end).
Describe Extramedullary fixation of bone fractures.
Extramedullary fixation is a method, where fractured
bone fragments are fixated with a construction that is
installed directly onto the fractured bone (screws).
Metal plates of various profiles and lengths are used for fixation and are attached to the cortex with screws or wire.
- cancellous screws (deeper threads)
- cortical screws (more shallow threads)
Describe cancellous bone screws.
Are for metaphyseal (neck of the bone) bone.
Designed to engage metaphyseal or epiphyseal bone, with larger outer diameter, deeper thread, and larger pitch.
Cancellous screws are either completely or partially threaded and are used primarily in the epiphysis or metaphysis.
epiphysis is the end of the bone, meta is the neck, dia is the shaft
Describe cortical bone screws.
Cortical screws for diaphyseal (midshaft) bone.
Designed to engage cortical bone, with smaller pitch
and less depth of the thread.
Cortical screws are fully threaded and designed for use in compact cortical bone.
Greater number of threads allows to engage the matrix of the relatively narrow-diameter cortical bone.
epiphysis is the end of the bone
What type of bone screw is this?
What type of bone screw is this?
What type of bone screw is this?
Describe orthopedic wire for bone fractures.
It is used in combination with other orthopedic implants to supplement axial, rotational, and bending support of fractures.
The term cerclage ligature is used to denote the use of orthopedic wire placed around the circumference of the bone.
Hemicerclage ligature or interfragmentary ligature
is the term used to denote wire that is placed through predrilled holes in the bone.
Describe traditional plates for bone fractures.
Such as the dynamic compression plate and limited contact dynamic compression plates.
Screws hold the plate in close contact with the bone, creating friction between the bone plate and bone and securing the construct.
The axial load through the bone actually creates a shearing force at the screw–bone interface.
Describe locking plates for bone fractures.
In locking plates, the screw heads thread into the plates, creating a locked fixed-angle system.
The axial force through the bone creates a compressive force at the screw–bone interface.
Locking plates create a stronger and stiffer construct compared with traditional plates.
Describe neutral fixation vs compression plates for bone fractures.
Neutral fixation (in plates): neutralizes physiologic forces acting on a section of bone that has been anatomically reconstructed and stabilized with screws and wire.
- A screw used in a neutral fashion (also known as a plate screw) is placed in the center of the screw hole (either round or oval shape) only to hold the plate in place.
A compression plate is used in case transverse or short oblique fractures, where it is possible to match the contact surface of the fracture line.
- A screw used in a compression fashion allows movement of the bone fragment relative to the plate as it is tightened, leading to compression of the fracture.
- Screw holes in compression plates have an oval shape that allows the screw to be placed at one end of the oval.
Describe Buttressing Versus Bridging in bone fixation.
A bone plate used in a buttressing fashion is
designed for metaphyseal fractures to prevent collapse of the area adjacent to an articular surface due to compressive forces. Supporting a broken bone from the side, like propping up a wall to prevent it from collapsing.
A plate used in a bridging fashion is designed to act as an internal splint to maintain the correct length and normal axial alignment when fracture ends cannot be anatomically reconstructed.
More simply, this placement bridges the fracture site to hold the bones in reduction and alignment, allowing the bone to heal.
Think of buttressing as holding something up, and bridging as holding something together.
meta = neck, epi = end, dia = mid
