External Coaptation

External skeletal fixation in large animals: A review

“…Bilateral uniplanar structures (type II) project from both sides of the limb (180° to each other) but are restricted to one plane (usually mediolateral). Bilateral biplanar ESF (type III) are threedimensional structures whose pins are externally interconnected by three sidebars, projecting from two different sides of the limb and occupying two planes (Auer 2019;Palmer 2012;Wright 2022). Biplanar ESF exhibits greater sagittal stability and better bone healing than uniplanar fixators (Figure 1).…”

“…Biplanar ESF exhibits greater sagittal stability and better bone healing than uniplanar fixators (Figure 1). In humans and small animals, these three-dimensional configurations optimize the resistance to torsional, shear, and compression forces to protect the bone from fracture propagation through the posterior holes (Lewis et al 2001;Wright 2022).…”

“…The technique of transfixation casting may be indicated for comminuted metacarpal/metatarsal fractures, fractures of the proximal and middle phalanges, and articular fractures (Figure 3). This consists of placing two or three proximal pins, proximal from the fracture focus, associated with the pins distal to the fracture, promoting symmetrical stress distribution (Auer 2019;Rossignol et al 2014;Wright 2022).…”

“…The design of the implant and the position of the insert in the fixator configuration significantly affect the strength and rigidity of the construction. The pin-bone interface is the most fragile point of all external fixation techniques, and premature failure of the transfixation screws can occur in these portions; this failure is considered the most common complication (Elce et al 2006;Wright 2022). Positive profile pins (with an external thread diameter greater than the core diameter) have higher stiffness than negative profile pins and are currently recommended by the literature for the construction of ESF in large animals (Auer 2019;Lescun et al 2007;Lewis et al 2001;Wright 2022) (Figure 4).…”

“…In cases of transfixation casting, the authors suggest that the pins be located in the bone epiphysis to reduce the risk of catastrophic fractures (Joyce et al 2006;Lescun et al 2007;Rossignol et al 2014;Williams et al 2014;Wright 2022). The use of three pins is recommended to maximize stiffness while preserving bone strength.…”