Attempts to perform direct reduction of highly comminuted long-bone fractures are rarely successful. An open surgical approach followed by internal fixation using bridge/buttress plating with bone plate and intramedullary rod (plate/rod) constructs is a commonly utilized stabilization method. Although this technique provides appropriate biomechanical stabilization, it results in additional surgical trauma to the surrounding soft tissue envelope and vasculature, which may result in delayed healing in some instances. The concept of a biological osteosynthesis was developed in order to preserve the integrity of the soft tissue envelope while concurrently achieving fracture stabilization using a variety of implant systems applied in a non-traumatic or minimally-invasive manner. Commonly applied fixation systems utilized with biologic osteosynthesis include interlocking nails, lengthening plates, plate/rod constructs, as well as a variety of locking fixation systems such as the LCP, SOP, and FIXIN systems. Many general veterinary practices do not have a sufficient caseload to justify maintaining an array of costly or infrequently utilized fixation systems.
The Synthes® Clamp-Rod Internal Fixator (CRIF) was designed to be a highly versatile, functional, and inexpensive fracture fixation system, well suited for biologic osteosynthesis techniques. However, a complete understanding of the CRIF/rod construct is essential in order to properly predict its clinical performance. Although a single report has recently described the biomechanical properties of the CRIF system when applied as a sole fixation system in a gap model using bone substitutes, to the author’s knowledge a biomechanical study comparing CRIF/rod constructs to traditional plate/rod constructs when applied to canine long bones has yet to be performed. The objective of this study is to compare the biomechanical properties of a 5 mm CRIF/rod constructed and a 3.5 mm LC-DCP/rod construct implanted in canine femora using a gap model. Based on the structural properties of these two systems, we hypothesize that compared to a 3.5 mm LC-DCP/rod construct, the 5 mm CRIF/rod construct will demonstrate increased stiffness and load to failure in bending and decreased stiffness and load to failure in torsion.