PhD student Mississippi State University Starkville, Mississippi
Bending of the Kirschner-wire or cutting the wire flush with the bone is commonly performed in clinical cases to reduce soft tissue irritation at the tibial tuberosity, however, no studies have evaluated the biomechanical characteristics of these techniques in dogs. Our objective was to evaluate the biomechanical properties and failure mode of the Kirschner-wire bending technique in a canine tibial tuberosity (TT) osteotomy fixation model. 24 tibias were harvested and randomly assigned to 1-of-2 groups (n=12/group). A standardized osteotomy of the TT was performed and fixed using two parallel 0.062” Kirschner-wires. Limbs acted as their own control with one receiving Kirschner-wire bending vs. the other group where the Kirschner-wire was cut flush with the bone following placement. Biomechanical testing was performed with the evaluation of yield, peak and failure loads, stiffness, and failure mode. Constructs in the bending group had significantly greater yield (P=0.001), peak (P=0.025), and failure loads (P=0.014). There was no difference in construct stiffness between groups (P=0.789). Tibial crest avulsion with concurrent Kirschner-wire pull out occurred in the bending group (12/12; 100%), which differed from the no bending group (12/12; 100%) were tibial crest avulsion and Kirschner-wire pulled through the TT (P>0.001). Bending the cranio-proximal free end of both Kirschner-wires following TT osteotomy fixation had superior biomechanical properties compared to Kirschner wires that were not bent at the enthesis. Further studies are warranted to determine the clinical significance of these findings in-vivo.
