The Relationship between the Angle of the Tibial Tunnel in the Coronal Plane and Loss of Flexion and Anterior Laxity after Anterior Cruciate Ligament Reconstruction

Abstract

Tension in an anterior cruciate ligament graft is greater with the knee in flexion when the angle of the tibial tunnel in the coronal plane is vertical or more perpendicular to the medial joint line of the tibia; however, the relationship of the angle of the tibial tunnel to knee function has not been studied. Greater graft tension may limit knee flexion or stretch the graft and increase anterior laxity. Five surgeons treated 119 subjects by reconstructing a torn anterior cruciate ligament using a double-looped semitendinosus and gracilis graft and a standardized technique. The femoral tunnel was drilled through the tibial tunnel. Radiographs were analyzed for tibial tunnel placement and a clinical evaluation was made 4 months postoperatively. Knees were assigned to subgroups according to the angle of the tibial tunnel in the coronal plane (65 degrees to 69 degrees, 70 degrees to 74 degrees, 75 degrees to 79 degrees, 80 degrees to 84 degrees, and 85 degrees to 89 degrees), with the angle of the latter subgroup being most vertical. Loss of flexion increased significantly from 0.5 degrees to 6.5 degrees and anterior laxity increased significantly from 0.5 to 2.2 mm as the tunnel angle was increased. The average angle of the tibial tunnel varied significantly, 11 degrees between surgeons (range, 69 degrees to 80 degrees). We found a tibial tunnel angle of 75 degrees or more is associated with greater loss of flexion and anterior laxity. Surgeons do not drill the angle of the tibial tunnel in the coronal plane accurately. We now routinely drill the tibial tunnel at an angle of 65 degrees to 70 degrees in the coronal plane because it may reduce loss of flexion and anterior laxity.

Reconstruction Technique Affects Femoral Tunnel Placement in ACL Reconstruction

“…In the current study, we also had difficulty placing the guide pin near the center of the ACL attachment using the transtibial technique in every specimen. The transtibial tunnel was drilled at 65°in the coronal plane [28,45] to enable placement of the guide pin lower on the wall of the notch. Using the offset guide in the over-the-top position allowed the femoral guide pin to be positioned at a desired distance from the posterior cortex but did not define the femoral tunnel location completely.…”

“…We placed the 7-mm tip extension of the marking hook against the base of the posterior cruciate ligament. The guide was angled to position the guide sleeve 1 cm above the pes anserinus and 2 cm medial of the tibial tubercle [38] to obtain sufficient tunnel length for the graft and form an approximately 65°angle [28,45] with Fig. 1 In the independent technique, a two-incision technique was used to place the femoral guide pin transfemorally from the outsidein, independently of the tibial tunnel.…”

Femoral tunnel drilling in anterior cruciate ligament reconstruction: Anteromedial or transtibial portal? Current review

“…Some studies have shown that with appropriate modifications of the TT surgical technique, better long-term outcomes and lower failure rates can be achieved [26][27][28] . These modifications include the use of an accessory transpatellar tendon portal for placement of the tibial aiming device; the use of a tibial tunnel starting point at the junction of pesanserinus and medial collateral ligament fibres; and adequate rotation of the 7 mm offset femoral wire aimer.…”

“…These modifications include the use of an accessory transpatellar tendon portal for placement of the tibial aiming device; the use of a tibial tunnel starting point at the junction of pesanserinus and medial collateral ligament fibres; and adequate rotation of the 7 mm offset femoral wire aimer. These modifications will improve lateralization and adjustment of the tibial aiming device to achieve 55°-60° of angulation of the tibial tunnel in the coronal plane [26][27][28] .…”

Reply to: Comments on Alentorn-Geli et al.: Anteromedial portal (AMP) versus transtibial (TT) drilling techniques in ACL reconstruction: a blinded cross-sectional study at two- to five-year follow-up

“…Studies referenced by Dr. Kini to support his first concern reported a tibial tunnel orientation of 60-70°in the coronal plane, but these angles were considered from the horizontal line, whereas the 20°in our study was considered from the vertical line [4,5,7]. Other authors perform the tibial tunnel with a mean angulation of 60.6°, ranging up to 74.2° [9].…”