An Anatomical Study on the Safe Placement of Orthopedic Hardware for Syndesmosis Fixation.

Articular cartilage and bony contact at the distal tibiofibular cartilage contact zone (TFCCZ) is variable. The appropriate placement of syndesmotic hardware would benefit from a more accurate characterization of the proximal extent of the TFCCZ allowing surgeons to place hardware that simultaneously improves biomechanical stability and decreases the risk of iatrogenic cartilage damage. In addition, Ilizarov wire fixation through the distal fibula and tibia can pass through the syndesmosis recess. Anatomically defining the proximal extent of this recess can help decrease the risk of inadvertent capsular penetration. This study anatomically defines the TFCCZ and syndesmosis recess establishing a safe and biomechanically advantageous distance from the plafond for orthopedic fixation. This study measured the height of the TFCCZ and the syndesmotic recess in 3158 anatomical and cadaveric specimens. A TFCCZ was present in 59% of the Robert J. Terry Anatomical Collection specimens. Maximal height of the TFCCZ averaged 5.7±1.7 mm (99% confidence interval [CI], 5.6-5.8 mm) for anatomical specimens and 5.6±1.6 mm (99% CI, 4.6-6.5 mm) for cadaveric dissections. The maximum TFCCZ height was 11.71 mm. Maximal height of the syndesmotic recess averaged 12.8±2.1 mm for anatomical specimens and 13.7±2.7 mm for cadaveric specimens. The "3 cm rule" appears to be appropriate for fine wire fixation accounting for capsular distension that can be associated with injuries but not applicable for syndesmotic fixation. There is a less than 0.1% chance of encountering the TFCCZ cartilage at 10.9 mm above the plafond and a less than 0.01% chance at 12 mm above the plafond. [Orthopedics. 2017; 40(2):e329-e333.].