The Use of Multiple Pin and Methylmethacrylate External Skeletal Fixation for the Treatment of Orthopaedic Injuries in the Dog and Cat

SummaryMultiple pin and methylmethacry-late external fixation devices were applied in 74 animals to successfully treat several different types of orthopaedic injuries. The major advantages associated with use of the technique included increased versatility in the location and angle of fixation pin place-ment and greater ease in placement of the connecting bar when compared with conventional clamp and connecting bar systems, particularly with transarticular placement of a device. The major disadvantages associated with the technique included, increased difficulty compared to conventional K-E systems regarding postoperative adjustment of the device and difficulty in removing individual pins that were loose or infected. Generally, removal of the device was not a problem, provided sufficient space was left between the connecting bar and the skin surface.Complications associated with the technique were similar to studies which have evaluated other types of external fixation and include fixation pin loosening, pin tract drainage or infection, fixation failure, osteomyelitis, angular limb deformity, mal-union, delayed union and nonunion.The multiple pin and methylmethacrylate external fixator provides a useful and effective method of repair for a wide variety of orthopaedic injuries. The use of methylmethacrylate as a connecting bar is a helpful adjunct to standard external fixation systems.The use of multiple pin and methylmethacrylate external fixation (MPMF) increases the versatility of the external fixation technique in small animal orthopaedic injuries. Disadvantages include difficulty in removing or replacing individual fixation pins.

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Analysis of the lower jaw exoskeleton in finite element programs

Medical alphabet ◽

10.33667/2078-5631-2021-24-88-92 ◽

2021 ◽

pp. 88-92

Author(s):

D. Yu. D’yachenko ◽

A. A. Vorob’ev ◽

Iu. A. Makedonova ◽

О. N. Kurkina ◽

S. V. D’yachenko ◽

...

Keyword(s):

Finite Element ◽

External Fixation ◽

3D Model ◽

Bone Fractures ◽

Maxillofacial Region ◽

Lower Jaw ◽

Fixation Devices ◽

Bone Fragments ◽

External Fixation Device ◽

Medical University

A special place in the methods of surgical treatment of bone fractures is occupied by transosseous osteosynthesis using external fixation devices of various designs.Objective: to analyze the lower jaw exoskeleton in finite element programs.Materials and research methods. During the research, 36 human lower jaws were involved from the museum of the Department of Oper-ative Surgery and Topographic Anatomy of the Volgograd State Medical University. They were scanned in 3D. All obtained images were loaded into a virtual scene reconstruction program. Fractures of the lower jaws in the corner area were modeled, an apparatus for external fixation of the lower jaw exoskeleton was installed, and the chewing load on the lower jaw was simulated. The place of application of the force was an area on a small fragment of a repositioned 3D model of the mandibular bone corresponding to the place of attachment of the masseter muscle. The evaluation of virtual studies was carried out according to the results of the stress-strain states of the bones and apparatus, the schedule of displacements of objects and the results of the analysis of the safety factor.Research results and discussion. In the course of evaluating the virtual placement of the mini-fixator wires of the apparatus for external fixation of the lower jaw exoskeleton, it was revealed that the main load is applied to the mini-fixator wires on a large fragment and the bone in the area of the wires. For the possibility of precise positioning of the osteofixers of the external fixation device, a device for the safe installation of the spokes of the lower jaw exoskeleton was also developed.Conclusion. Thus, on the basis of computer mathematical analysis, it can be argued that the developed design of the apparatus for external fixation of the lower jaw exoskeleton works under conditions of the maxillofacial region, performs reposition and fixation of bone fragments of the lower jaw under conditions of chewing functioning of the restored fracture of the lower jaw.

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