abs: K-Wire Insertion Angle
_{Small Animal Scientific Abstracts}

Medial patellar luxation is a common condition affecting the canine femoropatellar joint. Complications have been recorded in ≤48% of cases and include re-luxation or implant failure, often requiring revision surgery. Tibial tuberosity transposition (TTT) is an important surgical procedure to prevent re-luxation. Our objective was to evaluate the influence of k-wire insertion angle and tension band-wire-fixation (TBWF) following TTT in dogs. 24 pairs (n=48) cadaveric tibia were randomly assigned to one-of-four treatment groups (n=12/group). K-wires were placed at 0°, 30°, 0°+TBWF, and 30°+TBWF. Constructs were tested to failure with evaluation of K-wire angle, variance between K-wire angle, yield, peak, failure loads, construct stiffness and failure method were compared between groups. K-wire angles were 1.1±2.2°, 30.5±2.3°, 1.0±1.9°, and 29.4±2.5° respectively and differed between 0° and 30° groups (P <0.0001) regardless of TBWF. Yield (P=0.0095), peak (P<0.024) and failure loads (P <0.030) were significantly greater for 0° compared to 30° group constructs. Yield (P <0.004), peak (P<0.003) and failure force (P <0.003) was also significantly greater for 0°+TBWF compared to 30°+TBWF group. Addition of TBWF increased all assessed biomechanical parameters (P <0.0001) except stiffness, which did not differ among groups (P=0.068). Mode of failure differed (P=0.001) and occurred by TT avulsion in 0° and 30° group. Placement of K-wires perpendicular (0°) to the TT was biomechanically superior to those placed caudodistally (30°) in constructs regardless of TBWF augmentation. K-wire orientation is an important consideration during TTT in dogs with K-wire placed at 0° conferring increased strength to the repair.