Influence of plate type and placement on the immobilization of bilateral equine mandibular osteotomies: Ex vivo study

Abstract

Objective To determine the influence of plate fixation (locking or dynamic compression) and the site of application (ventral [V] or ventrolateral [VL]) on the resistance to bending of transverse mandibular fractures. Study design Ex vivo, simple randomized study. Sample population Mandibles harvested from adult equine cadavers (n = 18). Methods Bilateral osteotomies were created 1 cm caudal to the mental foramen and perpendicular to the long axis of each mandible. Mandibles were fixed with 1 of 3 methods: (1) VL dynamic compression plate (DCP), (2) V‐DCP, or (3) VL locking compression plating (LCP). Constructs were mounted on a custom testing jig and tested for resistance in bending by applying force to the rostral aspect of the mandible. Stiffness and change of distance of the dorsal osteotomy at 200 N were compared among constructs. Results VL‐LCP constructs were 5.25 and 2.42 times stiffer than V and VL constructs, respectively (P<.001). Change in the width of the osteotomy gap at 200 N of load was reduced 6.04 times when osteotomies were stabilized with VL compared to V (P<.001); no difference was detected between the VL and VL‐LCP constructs (P=.836). Conclusion Ventrolateral LCP fixation of equine transverse mandibular osteotomies provided greater resistance to bending compared with V and VL constructs. Clinical significance These results provide evidence to recommend fixation of transverse interdental mandibular fractures with VL‐LCP rather than with DCP in horses.

Polyaxial pedicle screw external fixation to stabilize oblique mandibular fractures in three standing, sedated horses

“…Neither PPS external fixation with intraoral wiring nor plate fixation of mandibular osteotomies achieved the stiffness, yield, and failure point of intact mandibles ex vivo. 5,6,16 Yield, failure, or osteotomy gap width up to 100-Nm torque were not different between LCP and dynamic compression plates. 16 Locking compression plates had higher stiffness and load to failure compared with PPS external fixators with intraoral wiring but no difference in yield.…”

“…1,2,4 Stabilization methods are chosen on the basis of the configuration, stability, and contamination of the fracture; accessibility of implants; and expertise and preference of the surgeon. Internal fixation allows a rigidly stable construct, 5,6 although it typically requires general anesthesia and implant placement beneath the skin in a frequently contaminated area. 4 Polyaxial pedicle screws (PPS) are frequently used in dogs and in man for spinal fusion and fixation, [7][8][9] and have recently been used in horses to achieve cervical vertebral stabilization.…”

“…Stabilization methods are chosen on the basis of the configuration, stability, and contamination of the fracture; accessibility of implants; and expertise and preference of the surgeon. Internal fixation allows a rigidly stable construct, 5,6 although it typically requires general anesthesia and implant placement beneath the skin in a frequently contaminated area 4 …”

External Unilateral Fixator of Own Design for the Treatment of Selected Mandibular Fractures in Horses

“…The best stabilization can be provided by the placement of an LCP plate at the ventrolateral site of the mandible [13,16,17]. In this particular situation involving unilateral fracture, strong fixation is not needed.…”

“…Depending on location and fracture configuration, the following surgical methods can be used: Wire loops in the oral cavity, wire loops enforced with synthetic materials, screws, Ushaped plate placed in the oral cavity, transmandibular Steinmann pins, steel plates (DCP, dynamic compression plates; LCP, locking compression plates) [10][11][12][13][14][15][16]. The use of DCP or LCP plates fixated directly on the bone at the ventrolateral site of the jaw provide the best stabilisation [17] but for opened infected fractures, this is not recommended. For the fixation of some fractures, only screws were needed.…”