The influence of a tension band fixation as an adjunct for arthrodesis of the metacarpophalangeal joint in the horse.

Abstract

OBJECTIVES: To determine the influence of a stainless-steel cable (SSC) tension band fixation as an adjunct to a locking compression plate (LCP) for arthrodesis of the equine metacarpophalangeal (MCP) joint. STUDY DESIGN: Experimental. An ex vivo biomechanical paired equine cadaver limb study. SAMPLE POPULATION: Five MCP joint pairs were collected from adult Thoroughbred horses, euthanized for reasons unrelated to orthopedic disease. METHODS: Each pair of MCP joints were randomly implanted with either a dorsally placed 5.5&#x2009;mm LCP and a palmarly placed 2.0&#x2009;mm SSC or a dorsally placed 5.5&#x2009;mm LCP alone. Each construct was tested in cyclic loading followed by single cycle to failure in axial compression. Displacement at a target load of 1&#x2009;kN over 3600&#x2009;cycles at 1&#x2009;Hz was recorded prior to single cycle to failure testing. RESULTS: In cyclic testing, displacement was not significantly different between the first and last 5% of testing cycles regardless of construct. Maximum displacement of each construct during cyclic testing was <1.1&#x2009;mm. In single cycle testing, the observed yield point did not reveal any difference between LCP and LCP-SSC (p&#x2009;=&#x2009;.440). The maximum load at failure was significantly higher in LCP-SSC compared to constructs with the LCP alone (p&#x2009;=&#x2009;.046). CONCLUSION: The addition of the SSC to the LCP did not statistically affect construct displacement during cyclic loading or construct yield load during subsequent single cycle to failure. CLINICAL SIGNIFICANCE: This study provided much needed information regarding the necessity of a tension band SSC application in the arthrodesis of the MCP/MTP joint in horses.