Plate failure by bending following tibial fracture stabilization in ten cats

July 30, 2015

This article describes the clinical findings and management of tibial fractures in cats in which plate osteosynthesis failed due to plate bending.

A.P. Morris1; A. A. Anderson1; D. M. Barnes2; S. R. Bright3; C. S. Knudsen4; D. D. Lewis5; A. Pozzi5; S. J. Langley-Hobbs6

1Anderson Abercromby Veterinary Referrals, Ockley, Surrey, UK; 2Eastcott Referrals, Swindon, Wiltshire, UK; 3Northwest Surgeons, Sutton Weaver, Cheshire, UK; 4Department of Veterinary Medicine, University of Cambridge, Cambridge, UK; 5Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA; 6Department of Clinical Veterinary Sciences, University of Bristol, Bristol, UK.

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ABSTRACT

This article describes the clinical findings and management of tibial fractures in cats in which plate osteosynthesis failed due to plate bending.

INTRODUCTION

The objective of this study was to retrospectively assess the clinical and radiographic features of cat tibial fractures in which plate osteosynthesis failed due to plate bending. The subsequent management of these fractures was also described

MATERIALS AND METHODS

Clinical history and radiographs of ten cats that had suffered plate bending following plate or plate-rod fixation of tibial fractures were reviewed for signalment, fracture configuration and repair method, initial post-operative and post-failure tibial alignment, revision treatment and outcome. Tibial alignment post-operatively and post-failure was compared using a paired T-test.

Figure 2B

RESULTS

All ten cats had sustained complete fracture of the tibia with an accompanying fracture to the fibula. Tibial fractures were generally oblique (4/10) or spiral (4/10) with mild comminution (8/10) and located in the middle (3/10) or distal (6/10) third of the tibia. Initial fracture stabilisation was with a plate (6/10) or plate-rod combination (4/10) with the plate applied to the medial tibial surface. Non-reduced, lateral tibial wedge fragments were present in five fractures. Mean time to implant failure was 24 days (range 2 – 56 days). Mean tibial valgus angle increased from 12.9° to 30.9° following bending of the plate (p=<0.01). Revision surgery was performed in 6/10 cats using orthogonal plating (4/10), stacked medial plates (1/10) or a combination of a stacked medial plate with an orthogonal cranial plate (1/10). Short-term outcome following revision surgery was favourable with improvement in tibial valgus in all the five fractures with follow-up data (p-<0.05).

REVISION SURGERY

DISCUSSION

Bending of plates applied to stabilise tibial fractures in these ten cats caused tibial valgus deformation. Implant failure was commonly associated with a reduced cis-cortex, but a non-reduced trans-cortex wedge fragment. Attention to plate and/or pin selection and application should be made to avoid a plate strain environment that exceeds the yield point of the plate. Revision using orthogonal plating or stacked medial plates was uniformly successful.

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