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.

In vitro comparison of V-Loc™ versus Biosyn™ in a one-layer end-to-end anastomosis of equine jejunum.

OBJECTIVE: To compare a unidirectional barbed suture (V-Loc™) to its suture material equivalent (Biosyn™) in a single-layer end-to-end anastomosis of equine jejunum. STUDY DESIGN: Experimental in vitro study. ANIMALS: Jejunal sections from adult horses (n = 5) without gastrointestinal disease. METHODS: Jejunal end-to-end anastomoses (n = 9) were performed for each group (V-Loc™, Biosyn™) with a continuous Lembert pattern with an interruption every 120°. Anastomosis construction time, luminal diameter, and number of suture bites were recorded. Anastomosis constructs were distended with fluid at 1 L/min until failure. Location and intraluminal pressure at failure were recorded and all measurements were compared between groups. RESULTS: V-Loc™ anastomoses were significantly faster to perform (13.1 ± 0.35 minutes) when compared to the Biosyn™ group (15.6 ± 0.72 minutes; P = .0004). No differences were observed for anastomotic index or number of suture bites. V-Loc™ anastomosis constructs had a significantly decreased bursting pressure (160 ± 11.6 mmHg) compared to Biosyn™ constructs (184 ± 16.9 mmHg; P = .01). CONCLUSIONS: V-Loc™ allowed faster construction time and did not cause a decreased anastomosis luminal diameter when compared with Biosyn™. V-Loc™ had a decreased bursting strength compared with Biosyn™, albeit well above pathologic pressures encountered clinically. Use of V-Loc™ may be beneficial for decreasing the amount of exposed suture material because of the absence of knots after construction and has the potential to result in decreased adhesions.

A polymer network architecture provides superior cushioning and lubrication of soft tissue compared to a linear architecture.

We report the relationships between linear vs. network polymer architecture and biomechanical outcomes including lubrication and cushioning when the polymers are applied to the surface of articulating knee cartilage. Aqueous formulations of the bioinspired polymer poly(2-methacryloyloxylethyl phosphorylcholine) (pMPC) exhibit tuneable rheological properties, with network pMPC exhibiting increased elasticity and viscosity compared to linear pMPC. Application of a polymer network, compared to a linear one, to articulating tissue surfaces reduces friction, lessens tissue strain, minimizes wear, and protects tissue - thereby improving overall tissue performance. Administration of the network pMPC to the middle carpal joint of skeletally mature horses elicits a safe response similar to saline as monitored over a 70 day period.