Modified Transtibial versus Anteromedial Portal Technique in Single Bundle ACL Reconstruction: Tomographic Comparision Femoral Tunnel Location

OBJECTIVES: The aim of this study is to determine whether it is possible to achieves a similar anatomical placement of the femoral tunnel with a modified transtibial ACL single bundle reconstruction tecnique compared to anteromedial transportal technique. Results were evaluated by tomographic comparisons between patients from both groups. METHODS: 36 patients (36 knees) who were candidates for an ACL single bundle reconstruction with patellar bone graft were included in the study. Patients were randomly allocated using a computerized sequence into two groups. 18 patients were assigned each group (modified transtibial vs AM transportal technique). Surgery was performed by the same surgical team in both groups. Femoral tunnel quadrant placement, oblicuity in the coronal and sagittal planes and diameter of the femoral tunnel were assesed tomographically blinded by two observers and statistical comparison between groups was realized. RESULTS: Average distance measured from posterior edge of the condyle to the femoral tunnel ( measured as a proportion respect to the T line) was similar in both groups ( Group I : 32.7 % +- 5.1% ; Group 2: 32.4 % +-4.4% , p = 0.85). Average distance measured from the Blumensaat line to the femoral tunnel (measured as a proportion respect to the H line) was similar in both groups ( Group I: 28.5% 4.49 % Group II , 31.5% of 4.83% p = 0.06). Average angulation values of the femoral tunnel in the coronal plane were lower in Group I than in Group II (Group I = 34.8 ° range 32.7 ° - 38.6 ° and 41.2 ° range Group II 36.7 ° - 43.1 ° P = 0.0016 ). Average angulation values of the femoral tunnel in the sagittal plane were similar in both groups (Group I 40.2 ° range 38.4 ° - 43.4 ° ; Group II 38 1 ° range 36.6 ° - 40.2 ° p = 0.17).. The average diameter of the femoral tunnel was significantly higher in group I than in Group II (Group I 11 mm 0.84 mm and 10.2 mm Group II 0.65mm p = 0.007) . CONCLUSION: The modified transtibial technique for single bundle ACL reconstruction has proved to be suitable to reproduce the anatomic placement of the femoral tunnel compared to the transportal AM technique.