Comparison of femoral tunnel length between transportal and retrograde reaming outside-in techniques in anterior cruciate ligament reconstruction

Purpose: To evaluate the accuracy of intraoperative femoral tunnel length measurement and to compare this between the transportal (TP) and outside-in (OI) techniques for double-bundle (DB) anterior cruciate ligament (ACL) reconstruction. Methods: Eighty patients underwent a DB ACL reconstruction using either the TP or the OI technique. The participants were randomized to either a TP group (I, 40 cases) or a OI group (II, 40 cases). The intraoperatively measured femoral tunnel length was recorded, and the postoperative femoral tunnel length was measured using computed tomography with OsiriX® imaging software. Results: The mean femoral tunnel lengths measured intraoperatively in Group II (38. 9 ± 3. 0 mm for anteromedial [AM], 39. 3 ± 3. 4 mm for posterolateral [PL]) were significantly longer than those of Group I (34. 8 ± 2. 7 mm for AM, 36. 0 ± 3. 2 mm for PL) (P < 0. 001). The mean AM femoral tunnel length measured postoperatively in Group II (33. 3 ± 3. 8 mm) was significantly longer than that in Group I (31. 1 ± 2. 9 mm) (P = 0. 006). The mean intraoperatively measured femoral tunnel length was significantly longer than that measured postoperatively in Groups I and II (P < 0. 001). Conclusion: After anatomic DB ACL reconstruction, the femoral tunnel length of the OI technique measured intraoperatively (AM/PL) and postoperatively (AM) was longer than those of the TP technique. The femoral tunnel length measured intraoperatively was longer than that measured postoperatively in both TP and OI technique. This study may help surgeons to measure femoral tunnel length accurately in anatomic DB ACL reconstruction with suspensory fixation device. Level of evidence: Prospective randomized controlled trial, Level I.