Anterior Cruciate Ligament Tibial Tunnel Research Articles

The "N+10 Rule" to Avoid Graft-Tunnel Mismatch in Bone-Patellar Tendon-Bone ACL Reconstruction Using Independent Femoral Tunnel Drilling.

Graft-tunnel mismatch (GTM) is a common problem in anterior cruciate ligament (ACL) reconstruction (ACLR) using bone-patellar tendon-bone (BPTB) grafts. Application of the "N+10 rule" in endoscopic ACLR with BPTB grafts will result in acceptable tibial tunnel length (TTL), minimizing GTM. Controlled laboratory study. Endoscopic BPTB ACLR was conducted on the paired knees of 10 cadaveric specimens using 2 independent femoral tunnel drilling techniques-accessory anteromedial portal and flexible reamer. The graft bone blocks were trimmed to 10 × 20 mm, and the intertendinous distance (represented by "N") between the bone blocks was measured. The N+10 rule was used to set the angle of the ACL tibial tunnel guide to the appropriate number of degrees for drilling. The amount of excursion or recession of the tibial bone plug in relation to the anterior tibial cortical aperture was measured in both flexion and extension. A GTM threshold of ±7.5 mm was set based on prior studies. The mean BPTB ACL intertendinous distance was 47.5 ± 5.5 mm. The mean measured intra-articular distance was 27.2 ± 3 mm. Using the N+10 rule, the mean total (flexion plus extension) GTM was 4.3 ± 3.2 mm (GTM in flexion, 4.9 ± 3.6 mm; GTM in extension, 3.8 ± 3.5 mm). In 18 of 20 (90%) cadaveric knees, the mean total GTM fell within the ±7.5-mm threshold. When comparing the actual measured TTL to the calculated TTL, there was a mean difference of 5.4 ± 3.9 mm. When comparing femoral tunnel drilling techniques, the total GTM for the accessory anteromedial portal technique was 2.1 ± 3.7 mm, while the total GTM for the flexible reamer technique was 3.6 ± 5.4 mm (P = .5). The N+10 rule resulted in an acceptable mean GTM in both flexion and extension. The mean difference between the measured versus calculated TTL using the N+10 rule was also acceptable. The N+10 rule is a simple and effective intraoperative strategy for achieving desired TTL regardless of patient-specific factors to avoid excessive GTM in endoscopic BPTB ACLR using independent femoral tunnel drilling.

Revision Anterior Cruciate Ligament Reconstruction and Increased Tibial Slope: When to Perform a Slope-Altering High Tibial Osteotomy

Background: Slope-correcting high tibial osteotomy (HTO) is gaining popularity for mitigating the impact of posterior tibial slope (PTS) on graft failure in patients requiring revision anterior cruciate ligament (ACL) reconstruction surgery. Biomechanical and clinical studies have demonstrated that PTS reduction results in decreased graft forces and satisfactory patient outcomes, making it an important technique in the setting of complex revision ACL reconstruction (ACL-R). Indications: Slope-correcting HTO can be performed for the management of recurrent knee instability after ACL-R due to a high PTS of 12° or greater. Technique Description: A 3- to 4-inch incision is made along the tibia using an anteromedial approach, and the exposed patellar tendon is protected using a retractor. The anterior compartment is exposed by an incision in the tibialis anterior fascia, followed by elevation of the tibialis anterior and placement of a Hohmann retractor. Subperiosteal elevation of the medial collateral ligament (MCL) is performed on the medial side of the tibial tubercle. The position of eventual screw fixation is marked, and a straight tubercle osteotomy is performed without anteriorization, leaving a freely exposed proximal tibia. Two K-wires are used to mark the location of the osteotomy. Soft tissue structures are protected with Hohmann retractors on both sides while using an oscillating saw to perform the osteotomy. A few degrees (1°-3°) of overcorrection are preferred. The osteotomy is completed, retaining 1cm of posterior hinge. The wedge is removed and reduced by hyperextending the knee under gentle manual traction. Pre-contoured, low-profile plates with locking screws are placed, with 3 screws proximally and another 3 distally. During concurrent ACL-R, the screws should leave room for drilling of the ACL tibial tunnel. Results: Studies investigating the effects of slope-correcting HTO concurrent to revision ACL-R have reported reduced anterior tibial translation and rotatory knee instability, improved patient-reported outcomes, and a reduction in graft failure risk. Description/Conclusion: Slope-reducing HTO is an essential technique in the arsenal of complex ACL surgeons aiming to correct the detrimental effect of an increased PTS on ACL graft integrity in the setting of revision ACL-R.

LATERAL MENISCUS TEARS IN ACL INJURED KNEE

Anterior cruciate ligament (ACL) tears can be associated with injuries to the lateral meniscus (LM) in about 20-30% cases. The lateral meniscus is more mobile than the medial and besides contributing to load transmission, it also stabilizes the knee in pivot-shift testing. The LM tears more often in the acute setting and its incidence does not rise in cases of chronic ACL instability. Lateral meniscus tears can be minor or major depending how severely the knee function gets impaired. Major tears are the complete radial tears, longitudinal bucket handle tears and posterior root tears. Male gender, high body mass index and contact injury mechanism are all risk factors for an LM tear. Anatomic factors which can contribute to LM tears include a high posterior tibial slope, varus malalignment and greater asymmetry between medial and lateral slopes. The lateral meniscus must be saved and repaired whenever possible to prevent residual knee instability and progressive lateral compartment arthritis, which can set in soon after a meniscectomy. The development of techniques and technology have rendered most tears amenable to repair. Longitudinal tears can be repaired by the all-inside or inside-out technique and the needles and devices must be inserted through a high anteromedial or transpatellar portal to prevent injury to the popliteal neurovascular structures. A lateral safety incision must always be used for inside-out repairs. Radial tears can be repaired by two horizontal sutures, a cross stich, a cross-tag or a hash-tag suture configuration. Lateral meniscus posterior root repairs are repaired by transtibial technique, either by drilling an independent anatomic tunnel or the sutures pulled out via the ACL tibial tunnel. The lateral meniscus has high healing rates and repairs yield improvement in functional outcome, beside delaying radiographic arthritis.

Tibial Spine Location Influences Tibial Tunnel Placement in Anatomical Single-Bundle Anterior Cruciate Ligament Reconstruction.

The purpose of this study was to assess the influence of tibial spine location on tibial tunnel placement in anatomical single-bundle anterior cruciate ligament (ACL) reconstruction using three-dimensional computed tomography (3D-CT). A total of 39 patients undergoing anatomical single-bundle ACL reconstruction were included in this study (30 females and 9 males; average age: 29 ± 15.2 years). In anatomical single-bundle ACL reconstruction, the tibial and femoral tunnels were created close to the anteromedial bundle insertion site using a transportal technique. Using postoperative 3D-CT, accurate axial views of the tibia plateau were evaluated. By assuming the medial and anterior borders of the tibia plateau as 0% and the lateral and posterior borders as 100%, the location of the medial and lateral tibial spine, and the center of the tibial tunnel were calculated. Statistical analysis was performed to assess the correlation between tibial spine location and tibial tunnel placement. The medial tibial spine was located at 54.7 ± 4.5% from the anterior border and 41.3 ± 3% from the medial border. The lateral tibial spine was located at 58.7 ± 5.1% from the anterior border and 55.3 ± 2.8% from the medial border. The ACL tibial tunnel was located at 34.8 ± 7.7% from the anterior border and 48.2 ± 3.4% from the medial border. Mediolateral tunnel placement was significantly correlated with medial and lateral tibial spine location. However, for anteroposterior tunnel placement, no significant correlation was found. A significant correlation was observed between mediolateral ACL tibial tunnel placement and medial and lateral tibial spine location. For clinical relevance, tibial ACL tunnel placement might be unintentionally influenced by tibial spine location. Confirmation of the ACL footprint is required to create accurate anatomical tunnels during surgery. This is a Level III; case-control study.

ACL Roof Impingement Revisited: Does the Independent Femoral Drilling Technique Avoid Roof Impingement With Anteriorly Placed Tibial Tunnels?

Background:Anatomic femoral tunnel placement for single-bundle anterior cruciate ligament (ACL) reconstruction is now well accepted. The ideal location for the tibial tunnel has not been studied extensively, although some biomechanical and clinical studies suggest that placement of the tibial tunnel in the anterior part of the ACL tibial attachment site may be desirable. However, the concern for intercondylar roof impingement has tempered enthusiasm for anterior tibial tunnel placement.Purpose:To compare the potential for intercondylar roof impingement of ACL grafts with anteriorly positioned tibial tunnels after either transtibial (TT) or independent femoral (IF) tunnel drilling.Study Design:Controlled laboratory study.Methods:Twelve fresh-frozen cadaver knees were randomized to either a TT or IF drilling technique. Tibial guide pins were drilled in the anterior third of the native ACL tibial attachment site after debridement. All efforts were made to drill the femoral tunnel anatomically in the center of the attachment site, and the surrogate ACL graft was visualized using 3-dimensional computed tomography. Reformatting was used to evaluate for roof impingement. Tunnel dimensions, knee flexion angles, and intra-articular sagittal graft angles were also measured. The Impingement Review Index (IRI) was used to evaluate for graft impingement.Results:Two grafts (2/6, 33.3%) in the TT group impinged upon the intercondylar roof and demonstrated angular deformity (IRI type 1). No grafts in the IF group impinged, although 2 of 6 (66.7%) IF grafts touched the roof without deformation (IRI type 2). The presence or absence of impingement was not statistically significant. The mean sagittal tibial tunnel guide pin position prior to drilling was 27.6% of the sagittal diameter of the tibia (range, 22%-33.9%). However, computed tomography performed postdrilling detected substantial posterior enlargement in 2 TT specimens. A significant difference in the sagittal graft angle was noted between the 2 groups. TT grafts were more vertical, leading to angular convergence with the roof, whereas IF grafts were more horizontal and universally diverged from the roof.Conclusion:The IF technique had no specimens with roof impingement despite an anterior tibial tunnel position, likely due to a more horizontal graft trajectory and anatomic placement of the ACL femoral tunnel. Roof impingement remains a concern after TT ACL reconstruction in the setting of anterior tibial tunnel placement, although statistical significance was not found. Future clinical studies are planned to develop better recommendations for ACL tibial tunnel placement.Clinical Relevance:Graft impingement due to excessively anterior tibial tunnel placement using a TT drilling technique has been previously demonstrated; however, this may not be a concern when using an IF tunnel drilling technique. There may also be biomechanical advantages to a more anterior tibial tunnel in IF tunnel ACL reconstruction.

Femoral and Tibial Graft Tunnel Parameters After Transtibial, Anteromedial Portal, and Outside-In Single-Bundle Anterior Cruciate Ligament Reconstruction

Background: Anatomic graft tunnel placement is recommended in anterior cruciate ligament (ACL) reconstruction to restore knee joint stability and function. Transtibial (TT), anteromedial portal (AMP), and outside-in (OI) retrograde drilling surgical techniques have been described for tibial and femoral bone tunnel preparation. Purpose/Hypothesis: The purpose of this study was to evaluate the bone tunnel parameters and compare the ability of 3 different surgical techniques to achieve placement of the ACL femoral and tibial bone tunnels at the center of the native ACL femoral and tibial attachment sites. The hypothesis was that tunnel placement using an AMP or OI technique would result in optimized tunnel parameters and more closely reconstruct the center of the native ACL femoral attachment site. Study Design: Cohort study; Level of evidence, 3. Methods: The study population consisted of 100 patients undergoing anatomic single-bundle ACL reconstruction using multiple-stranded hamstring tendon grafts. In group 1 (n = 36), the femoral tunnel was drilled using a TT surgical technique; in group 2 (n = 32), the femoral tunnel was drilled through an AMP; and in group 3 (n = 32), the femoral tunnel was created by use of an OI technique with retrograde drilling. Computed tomography (CT) scans were obtained postoperatively, and characteristics of femoral and tibial tunnel apertures were correlated to femoral and tibial measurement grid systems. The position of the resulting tibial and femoral bone tunnels for each group was compared with the center of the native ACL attachment sites. Results: There were statistically significant differences (P < .05) for the ACL femoral tunnel between the 3 groups with respect to intercondylar height, total tunnel length, graft fixation length, tunnel axis, and tunnel entry angle. Statistically significant differences (P < .05) were found for the ACL tibial tunnel with respect to anteroposterior tunnel position and sagittal tunnel axis between the TT and both the OI and AMP techniques. The OI surgical technique produced more oblique and anatomically correct femoral tunnel apertures and longer femoral tunnel lengths compared with the AMP technique. Both AMP and OI techniques resulted in a more precise replication of intercondylar tunnel depth and height. There was no statistically significant difference for graft fixation length between the AMP and OI techniques. Conclusion: The AMP and OI surgical techniques were superior in positioning the ACL femoral tunnel at the center of the native ACL attachment site compared with the TT technique. An acceptable graft fixation length was obtained for all 3 surgical techniques.

Comparison of MRI Results of Grafts Obtained by Unilateral Anterior Cruciate Ligament Reconstruction Either Using Anteromedial Portal Only or Transtibial Method with Contralateral Healthy Knee

Objectives:Our aim is to compare graft angles and tibial tunnel insertion in patients undergone single bundle ligament reconstruction using anatomical anteromedial (AM) and transtibial (TT) method with the contralateral healthy knee by using MR imaging. And to investigate correlation of this evaluation with functional results.Methods:We investigated 96 knees of 48 patients undergone anterior cruciate ligament (ACL) reconstruction with AM or TT method. 23 of 48 patients were operated with AM method. These patients were named as Group A. 25 patients were operated with TT method and named as group B. MRI was taken for both knees in each group postoperatively at the mean 10.47 (9-15) and 11.72 (9-17) months, respectively. Angle between ACL graft and anatomical axis of tibia in coronal and sagittal plane, [Sagittal ACL graft angle (SAGA), Frontal ACL graft angle (FAGA)], middle insertion point on tibial articular surface, [ Sagittal ACL middle point (SGMP), Frontal ACL tibial tunnel middle point (FTMP), and Sagittal ACL tibial tunnel middle point(STMP)] was assessed by three orthopaedic surgeons. Values in both groups, inter observer, values between operated and healthy knees and differences between two groups were statistically evaluated. Functional scores between operated and healthy knees were evaluated with the Lysholm scoring system.Results:Inter observer results were statistically significant in group A between operated and healthy knees for 1st and 2nd observers in SAGA values and for 1st and 3rd, and 2nd and 3rd observers in FAGA values (p<0.05). In group B there was statistically significant difference in SAGA values for 1st and 2nd, and for 2nd and 3rd observers and in FTMP values for 1st and 3rd, and 2nd and 3rd observers (p<0.05). Statistically significant difference was detected between SAGA, FAGA and SGMP values of operated and healthy knees of A and B groups in all three observers’ evaluation (p<0.05). No statistically significant difference was detected between STMP values of operated knees and SGMP values of healthy knees in both groups (p>0.05). Statistically significant difference was detected between SAGA and FAGA values of operated knees in both groups (p<0.05). There was statistically significant difference in Lysholm scores between group A and B (p<0.05). Nonetheless there was no statistically significant difference between the Lysholm scores of operated knees in A and B groups (p>0.05).Conclusion:ACL reconstruction surgery with TT and AM methods do not provide anatomical reconstruction in Sagittal plane. Moreover, functional results were not as good as contralateral healthy knees. Although tibial tunnel was in anatomical position in both TT and AM methods, the posterior insertion of graft is thought to be the result of anterior placement of interference screw.

Effect of Reamer Design on Posteriorization of the Tibial Tunnel During Endoscopic Transtibial Anterior Cruciate Ligament Reconstruction

Background: It is known that small alterations in tunnel positioning during anterior cruciate ligament (ACL) reconstruction significantly affect ACL length and tensioning patterns as well as alter force vectors and joint kinematics. Purpose: To compare the amount of inadvertent posteriorization of the ACL tibial tunnel anatomy during transtibial ACL femoral reaming in the “over-the-top” position with a full femoral reamer versus a half femoral reamer, in comparison to the native tibial ACL footprint. It is hypothesized that the half reamer will result in less distortion of tibial tunnel anatomy and improved anatomic footprint coverage. It is also hypothesized that the true center of the tibial ACL footprint lies more anterior than previously described. Study Design: Controlled laboratory study. Methods: Eight cadaveric knee specimens were securely fixed to a stationary table at 90° of flexion and neutral rotation. After removal of the anterior capsule and patella, native joint anatomy was precisely recorded with a digitizer accurate to 0.05 mm. Tibial and femoral tunnels were then drilled in the manner of transtibial ACL reconstructions using the optimal tibial starting point of 15.9 mm below the medial plateau and 9.8 mm posteromedial to the medial margin of the tibial tubercle. After the 11-mm tibial tunnel was drilled, femoral tunnels were first drilled with a 10-mm half-fluted reamer, followed by a 10-mm full reamer. Each tibial tunnel’s location and geometry relative to the native ligamentous insertion sites and joint anatomy were digitized. Results: Digitized measurements of ACL insertional anatomy demonstrated that the center of the native ACL tibial footprint was 2.0 ± 0.49 mm (range, 1.1-2.7 mm) anterior to the posterior aspect of the lateral meniscus’ anterior horn. Use of the 10-mm full femoral reamer resulted in a tibial-articular aperture that had a posterior edge 4.35 mm more posterior (P = .049) and extra-anatomic (P = .006) than the footprint of the 10-mm half femoral reamer. Conclusion: Half-fluted reamers may be more advantageous for femoral tunnel reaming with a more oblique transtibial approach, as they result in less posterior tibial tunnel expansion than full reamers, possibly leading to improved graft function. Based on the digitized anatomy, the center of the tibial attachment site is anterior to the posterior aspect of the lateral mensicus’s anterior horn, which has been traditionally described as the anatomic center. Clinical Relevance: Use of half-fluted reamers for transtibial femoral tunnel reaming could lead to more anatomic tunnel placement and possibly improved graft mechanics after transtibial single-bundle ACL reconstruction.

Tibial Tunnel Aperture Irregularity After Drilling With 5 Reamer Designs

Background: There is limited information in the literature on comparisons of antegrade versus retrograde reaming techniques and the effect on the creation of anterior cruciate ligament (ACL) tibial tunnel entry and exit apertures. Hypothesis: Proximal and distal apertures of ACL tibial tunnels, as created with different reamers, will be affected by type of reamer design. Study Design: Controlled laboratory study. Methods: Forty skeletally mature porcine tibias with bone mineral density values comparable with a young athletic population were included in this study. Five 9-mm reamer models were used (3 antegrade: A1, smooth-bore reamer; A2, acorn-head reamer; A3, flat-head reamer; 2 retrograde: R1, retrograde acorn reamer; R2, single-blade retrograde reamer), and a new reamer was used for each tibia (8 reamer-tibia pairs per reamer model). All specimens underwent micro–computed tomography scanning, and images were reconstructed and analyzed using 3-dimensional image analysis software. Aperture rim fractures were graded on a 0-IV scale that described the proportion of the fractured aperture circumference. Specimens with incomplete apertures were also recorded. Because of the unique characteristics of various tunnels, intratunnel characteristics were observed and recorded. Results: In sum, 1 proximal and 7 distal aperture rim fractures were found; 3, 0, and 4 distal aperture rim fractures were found with groups A1, A2, and A3, respectively. Incomplete apertures were more commonly found at the distal aperture (n = 15) than the proximal aperture (n = 8); there were no tibias with this finding at both apertures. All incomplete distal apertures occurred with the retrograde technique, and all incomplete proximal apertures occurred with the antegrade technique, most commonly with reamer design A3. An added finding of tunnel curvature at the distal aspect of the tunnel was observed in all 8 tibias with R1 reamers and 5 tibias with R2 reamers. This phenomenon was not observed in any of the tibias reamed with the antegrade technique. Conclusion: Anterior cruciate ligament tibial tunnel aperture characteristics were highly dependent on reamer design. Optimal proximal aperture characteristics were produced by the retrograde reamers, whereas optimal distal aperture characteristics were obtained with the antegrade reamers. In addition, a phenomenon of tunnel curvature in retrograde-type reamers was found, which may have effects on ACL graft or screw fixation. Clinical Relevance: Differences in tunnel aperture shapes and fractures depend on reamer design. This information is important for the creation of ACL reconstruction tunnels with different reamer designs.

The Effect of Interference Screw Diameter on Fixation of Soft-Tissue Grafts in Anterior Cruciate Ligament Reconstruction

The purpose of this study was to evaluate the effect that interference screw diameter has on fixation strength of a soft-tissue anterior cruciate ligament (ACL) graft. We prepared 32 fresh-frozen bovine tibiae with 9-mm ACL tibial tunnels. Accompanying 9-mm soft-tissue bovine Achilles grafts were also prepared. Bioabsorbable interference screws of increasing diameters were used for tibial fixation. There were 4 groups, consisting of 8-, 9-, 10-, and 11-mm screws for fixation of the 9-mm graft in the 9-mm tunnel. Tensile testing and cyclic loading from 50 to 250 N at 2 Hz for a total of 1,500 cycles were performed with a hydraulic biaxial materials testing machine. Graft slippage was measured with a video analysis technique with photo-reflective markers. At the end of cyclic testing, the grafts were loaded to failure, and the ultimate strength was recorded. All grafts failed at the tendon-bone-screw interface. The ultimate strength (+/- SD) was greatest for the 11-mm screw (624 +/- 133 N), with slightly decreased strength for the 10-mm (601 +/- 54 N), 9-mm (576 +/- 85 N), and 8-mm (532 +/- 185 N) screws. Graft slippage (+/- SD) was least for the 9-mm screw (2.65 +/- 2.38 mm). There were no statistically significant differences in ultimate strength and graft slippage between screws (P = .45 and P = .34, respectively). All interference screws tested provided adequate fixation strength. The results of this study show no statistical significance for ultimate strength or graft slippage with variable screw diameter. Aperture fixation with the interference screw technique provides adequate stability for soft-tissue grafts in ACL reconstruction. Although no statistical significance was found, there was a trend toward less graft-site motion when we used a screw diameter equal to tunnel size.

The 1:1 versus the 2:2 Tunnel-Drilling Technique

Background Double-bundle anterior cruciate ligament (ACL) reconstructions involve drilling 2 tibial tunnels separated by a narrow 2-mm bone bridge. The sequence of reaming and drilling the tibial tunnels for double-bundle ACL reconstructions has not been defined. Hypothesis Fixing a graft in the posterolateral ACL tibial tunnel before reaming the anteromedial tibial tunnel will reduce the number of complications, as compared with drilling both the anteromedial and posterolateral tunnels before graft fixation, when performing double-bundle ACL reconstructions. Study Design Controlled laboratory study. Methods Twelve porcine tibias were divided into 2 groups of 6 specimens. Fresh bovine extensor tendons grafts were fixed in 7-mm tunnels reamed using an inside-out method. Grafts were fixed in a retrograde fashion with 7-mm bioabsorbable retrograde screws. The tibias in group 1 were reconstructed by reaming and reconstructing the posterolateral tunnel before reaming and securing the graft for the anteromedial tunnel (ie, 1:1 method), whereas those in the second group were reconstructed by reaming both tunnels before graft fixation in either (ie, the 2:2 method). The specimens were biomechanically tested with cyclic and load-to-failure parameters. Results Cyclic testing revealed no significant difference between the 2 methods in displacement or stiffness. In load-to-failure testing, the 1:1 group withstood significantly higher initial failure loads and ultimate loads. Pullout displacement was significantly higher for the 1:1 group. Whereas no tibias in the 1:1 group sustained fractures, 4 from the 2:2 group demonstrated a bone bridge fracture. Conclusion Soft tissue ACL grafts fixed in the tibia with the 1:1 method withstood significantly higher initial and ultimate failure loads and were stiffer than the grafts fixed with the 2:2 method. Tibias fixed with the 1:1 method were also less susceptible to bone bridge fracture. Clinical Relevance The potential for a lower complication rate and greater pullout strength seen with the 1:1 method may prove useful to surgeons performing anatomic double-bundle ACL reconstructions, in addition to other procedures involving reconstructing 2 closely positioned tunnels, including anatomic posterolateral corner and medial collateral reconstructions.

Posterolateral Sling Reconstruction of the Popliteus Tendon: An All-Arthroscopic Technique

Abstract Injuries to the posterolateral corner of the knee present with variable injury patterns that have produced a number of reconstructive procedures in the literature. We present an all-arthroscopic technique that reconstructs the popliteus tendon using either a semitendinosus autograft or an anterior tibialis allograft. After exposure of the posterior tibia by use of the posteromedial and trans-septal portals for visualization and posterolateral portal as a working portal, the popliteus musculotendinous junction is identified. In preparation for tibial tunnel drilling, a Kirschner wire is passed from the Gerdy tubercle to the popliteus musculotendinous junction on the posterior tibia, which is localized by use of an anterior cruciate ligament tibial tunnel guide brought in through the posterolateral portal. The 6-mm tibial tunnel is then created. The femoral insertion site is identified by use of the anterolateral portals for visualization and by use of the accessory superolateral portal for debriding the synovial fold at the insertion of the popliteus tendon. A K-wire is inserted, and a socket is established. The selected graft is then implanted by passing the graft through the tibial tunnel from anterior to posterior with a passing suture and pulling it up anteriorly and superiorly to the femoral socket. The graft is tensioned with the knee in 90° of flexion and in neutral rotation before fixation of both ends of the graft with bio-interference screws.