## 4 Discussion  
External fixators are valuable for the treatment of open and infected fractures involving the horizontal part of the mandible [5; 8; 9]. Like any other methods, external fixation has its advantages and disadvantages. The following advantages offered by this fixator can be distinguished: Easy application, easy removal, minor application- and removal-related tissue injury, small size that does not hinder everyday functioning of the patient (drinking and eating), and the possible use in open and infected fractures. This method ensures a good view of the wound and its possible treatment. General anesthesia is not necessary to remove implants from the bone, while the entire fixator can be removed in a stable, without the need to transport the patient to a clinic. The main rod, with arms and pin couplings, is mounted at some distance so that the fixation is not too rigid, which promotes the formation of abundant bone scarring. On the other hand, the following disadvantages have to be taken into consideration: transmission of infection along the implants, and implant loosening. These phenomena are rather distinct after several weeks of treatment because this period of time is usually sufficient to achieve desired bone union. Pinkless external fixator (PEF) created by Swiss scientists has many advantages, like easy application, easy removal, minimal soft tissue trauma, but the biggest disadvantages are its large construction, high risk of unintended removal, and clamps loosening [8; 9]. While attempting to design the fixator, the following requirements set for good fixators were taken into account:  
1. Easy application--the time needed to place the fixator should be as short as possible, which is of great importance for the patient's safety. The longer the patient remains under anesthesia, the greater the risk of possible complications. In order to place the fixator, it is necessary to insert four implants into the bone and connect them with the fixator. Four holes with a diameter of 4.5 mm have to be drilled to insert pins into the bone. Thus, time and bone damage are not extensive. The use of an appropriate driller for this task makes it much easier. Due to self-tapping pins, there is no need to tap holes into the bone, which significantly shortens time. The fixator can be assembled in advance before the surgery so that time is saved at this stage. It is mounted with pins in a rather short time provided that appropriate assembly tools are available. In this case, application of special tools significantly reduces time to insert the pins and to place the fixator. Its elements are external to the bone, eliminating issues related to a small amount of soft tissue, which in turn, poses a challenge in case of plates use (difficulties with stitching the wound and hiding the plates under the skin). Surgery is conducted at a certain distance from the fracture site, therefore, reducing the risk of infection. Comparing the easy applications of other fixators, the PEF is the easiest one [8; 9]. 2. Easy removal--it is often more difficult to remove plates and screws than to place them due to bone scarring and lesions in the surrounding soft tissue. Removing the fixator and pins from the bones is very easy and quick. It is worth emphasizing that no general or local anesthesia is needed. At most, it may be necessary to sedate the patient as the sounds made by the tools may cause the horse to become anxious. Unscrewing the individual elements of the fixator is painless, similar to the removal of pins from bone. This is an important factor taken into account when deciding whether to start treatment. The ultimate cost is substantially reduced and, furthermore, the patient is not exposed to additional general anesthesia and the possible risks arising from it. The fixator may be successfully removed under field conditions without the need to transport the horse to the clinic. Often, horses sustain serious injuries during transport. 3. Minor tissue injury related to both placement and removal.