Mechanical comparison of application of locking intramedullary nail to locking compression plate in the ovine metatarsus.

Background: The metatarsal bone is commonly utilized in preclinical fracture models in sheep. A majority of studies achieve fracture stabilization with bone plating, but more recently intramedullary interlocking nails (IMN) have been utilized. The mechanical properties of this unique surgical technique utilizing an IMN has not yet been fully elucidated or compared to the traditional locking compression plating (LCP) technique. We hypothesize that a mid-diaphysis metatarsal critical-sized osteotomy stabilized with an IMN will provide equivalent mechanical stability to LCP with less variance of mechanical properties across specimens. Methods: Sixteen ovine hind limbs were transected at the mid tibia with soft tissue intact and utilized for implantation. A 3-cm osteotomy was created in the mid-diaphysis of all metatarsi. For the IMN group, a 147 mm × 8 mm IMN was implanted from distal to proximal through the sagittal septum of the distal metatarsus and the bolts locked in place using an IMN guide system. For the LCP group, a 3.5-mm 9-hole LCP was secured to the lateral aspect of the metatarsus with three locking screws in the proximal and distal holes leaving the central three holes empty. All metatarsal constructs were fitted with three strain gages on proximal and distal metaphyses and the lateral aspect of the IMN or LCP at the osteotomy site. Non-destructive mechanical testing was performed in compression, torsion, and four-point bending. Results: The IMN constructs showed overall greater construct stiffness with less variance in strain between constructs than the LCP constructs in 4-point bending, compression, and torsion. Conclusions: IMN constructs may provide superior mechanical properties for a critical-sized osteotomy model of the ovine metatarsus when compared to lateral LCP constructs. Further in vivo investigation comparing characteristics of fracture healing between IMN and LCP is warranted.

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

OBJECTIVE: To report the radiographic, surgical and postoperative features in horses with unstable oblique mandibular fractures secured with polyaxial pedicle screws (PPS) external fixation construct and intraoral wiring. ANIMALS: Three client-owned horses. STUDY DESIGN: Short case series. METHODS: Two horses each had a unilateral fracture, which did not improve after conservative management, and one horse had bilateral fractures. Clinical and radiographic features were documented. Polyaxial pedicle screw external fixators and intraoral tension band wiring were applied in standing horses after combining sedation and regional nerve anesthesia. Intraoral wires were implanted through a lateral buccotomy between teeth (two horses) or burred through exposed crown (one horse) and then secured around the incisors. The PPS were inserted under radiographic guidance to avoid tooth roots. Healing was assessed with radiographic examination. The PPS external fixator rod and intraoral wires were removed first. The mandible was manipulated, and, if it was stable, the PPS were removed. RESULTS: Implants were removed at 6, 8, or 10 weeks after the mandibles were palpably stable. Complications included broken wires in one horse, bone sequestration in one horse, and infection in one horse. Follow-up communication with the owners 12 to 18 months later confirmed complete healing without further complications of the fractured mandibles or teeth. CONCLUSION: Polyaxial pedicle screw external fixation led to fracture healing and a return to function in all three horses. The complications encountered did not preclude a successful outcome. CLINICAL SIGNIFICANCE: Polyaxial pedicle screw external fixation coupled with intraoral wiring provides an alternative to treat unstable equine mandibular fractures without general anesthesia.

Geographic Disparities in Clinical Characteristics of Duodenitis-Proximal Jejunitis in Horses in the United States.

Duodenitis-proximal jejunitis (DPJ) is an idiopathic and potentially fatal disease of horses characterized by abdominal pain, proximal intestinal inflammation, and subsequent gastric and small intestinal fluid accumulation. Although this disease is known to be costly and life threatening in the equine industry, the severity of clinical signs can vary widely, and an exact etiology has yet to be elucidated. This study looked to identify differences in clinical parameters of horses with DPJ between geographic regions in an effort to corroborate anecdotal reports and support theories of differing etiologies. Case records were compared from veterinary academic referral hospitals in three different geographic locations in the United States to determine if significant differences in clinical, clinicopathologic, and prognostic characteristics exist among horses with DPJ. Clinical measurements on presentation that were significantly different between regions included heart rate, peritoneal total protein, albumin, anion gap, aspartate aminotransferase, gamma-glutamyl transferase, sodium, chloride, potassium, and creatinine. Duration of hospitalization and maximum body temperature while hospitalized were also different between regions. There were no significant differences in peritoneal cell count, total white blood cell count, neutrophil count, band neutrophils, calcium, total plasma protein, temperature on presentation, duration of reflux, total reflux volume, or age between hospitals. The mortality rates between hospitals were not significantly different. Increased severity of clinical signs and biochemical abnormalities were identified in the Southeastern United States hospital compared with the Northeastern and Western hospitals. A prospective, multicenter case-control study could identify risk factors contributing toward regional differences in this disease in the future.