Study On Secure Tunnel In The Fixation Of Talar Neck Fracture Based On Digital Technology

ObjectiveTo investigate the option parameters including the passways, length and angel using canulated screws to fix talar neck fracture while the screws were inserted through the medial wall of talus in order to give valuable reference for clinical treatment.MethodsWith the permission to utilize the skeletal images of volunteers’,the conditions should be defined.Inclusion criteria:The age of volunteers was from20to60,the height of male volunteers was from165to185centimeters,and the femal’s was from155to175centimeters.The body mass index(BMI) was less than25.The volunteers who were not heavy manual workers or standing working for long time had no history of ankle or foot fractures,and there were no evidence of degeneration changes of ankle joints in X-ray.At last there were33males joined in this study with an average age of43.7(21-59) years and with an average height of176.0(168-184) centimeters. There were22females joined in this study with an average age of43.2(22-60) years and with an average height of165.4(158-172) centimeters. After the volunteers’ankel joints and feet were scaned by CT scanner,the reconstructed images were stroed in CD cards and the slice thickness is0.75milimeters.The SuperImageTM Orthopedics Edition1.1software was used to display the images and performed three dimensional reconstruction.Then we observed the height of talar neck and tarsal canal. We built the three dimensional reconstructed models that screws passed through tarsal canals. We observed the maximal length and angle that screws were inserted at the middle1/3medial wall of talus and at the inferior1/3medial wall of talus and the Screws were inserted in two directions.At last, the data were analysed with SPSS13.0software. ResultsThe height of talar neck and tarsal canal had no significant difference between left and right side in same gender (P>0.05).The height of male’s talar neck was greater than the female’s (P<0.05).The models of screws passing trough tarsal canals was gained.The screws’length and angle in and different directions of scerws fixation were also obtained.The male screws’length were longer than female (P<0.05),and there was no significant difference in the angel of fixation (P>0.05).The maximal length of screws had no difference in the same gender between two sides of the feet (P>0.05).When the screws were inserted in the middle1/3of the medial wall of talus,The angle of fixation was much wider than that when the screws were inserted in the inferior1/3of the medial wall of talus.The maximal length was obtained in the direction of the screw that arrived at the superior border of lateral wall of talus while the screw was inserted in the middle1/3of the medial wall of talus.When screws were inserted in the inferior1/3of the medial wall of talus,the maximal length was gained in the direction of the screw closed to the tarsal canal,and the minimal length was gained in the direction of the screw arriving at the depression of the lateral wall of talus.At last,we calculated the safty range of the length and angel of screws’ fixation.ConclusionWe should avoid damaging the blood of talus while the screws that passed in the tarsal canal and destroyed the tarsal canal artery were inserted in the medial wall of talus.The middle1/3of the medial wall of talus is the most favourable choice to the fixation. The length of screws are different between male and femail because of physiological diversities.So surgeons should select screws appropriately. Combining the digital technology with internal fixation to talar neck fracture is beneficial to make preoperative plan and could promote the operation’s security and feasibility.