Anatomic Tibial Tunnel Research Articles

Reliability of the Tibial Spine Versus ACL Stump in Assisting Tibial Tunnel Positioning During ACL Reconstruction: Analysis Based on 3-Dimensional Computed Tomography Modeling

Background: Several techniques have been used by surgeons for anatomic tibial tunnel placement in anterior cruciate ligament (ACL) reconstruction, including the ACL stump positioning (ASP) technique and the tibial spine positioning (TSP) technique. Purpose/Hypothesis: The purpose of this study was to evaluate whether bony landmarks (medial and lateral tibial spine [MLTS]) can be a reliable reference for improving the accuracy of tibial tunnel placement in anatomic single-bundle ACL reconstruction compared with the ACL stump. It was hypothesized that the MLTS would not be a reliable bony landmark for tibial tunnel placement. Study Design: Cohort study; Level of evidence, 3. Methods: The 3-dimensional computed tomography images of 111 patients who underwent ACL reconstruction between 2020 and 2021 were included in this study. For tibial tunnel placement, the ASP technique was used in 49 patients, and the TSP technique was used in 62 patients. The 3-dimensional computed tomography images were reconstructed to enable measurements of the locations of the MLTS and tunnel center based on a grid method. Statistical analysis was conducted to compare the MLTS location and tibial tunnel position as well as the accuracy (mean distance of each actual location from the anatomic center) and precision (standard deviation of the accuracy, indicating the reproducibility of the tunnel position) of the tunnel position between the ASP and TSP groups. Results: Significant differences were observed between the ASP and TSP groups in terms of the tibial tunnel position on the mediolateral axis (46.7% ± 2.0% vs 45.9% ± 2.2%, respectively; P = .034), while no significant differences were found in terms of the accuracy (4.1% vs 4.6%, respectively; P = .259) or precision (2.1% vs 2.1%, respectively; P = .259) of tibial tunnel positioning between the 2 groups. Conclusion: In anatomic single-bundle ACL reconstruction, the use of the MLTS for tibial tunnel placement achieved comparable accuracy and precision compared with the use of ACL remnants, supporting its role as a reliable bony landmark in tibial tunnel positioning.

Revision Posterior Cruciate Ligament Reconstruction Technique

Background: Revision posterior cruciate ligament reconstruction (PCLR) is challenging, especially in existing semi-anatomic tunnels, whereas there is an increased risk of overlapping with a new positioned anatomic tunnel. Few cases were published with no consensus regarding the optimal operative technique. Indications: A 22-year-old male patient, with failed PCLR with hamstring autograft in 2020 due to improper tunnels placement, presented for pain and instability of his right knee. Physical examination revealed a positive posterior drawer and reverse Pivot-Shift test, with no varus-valgus or rotational laxity. Radiograph showed no signs of arthritis, normal tibial slope, and normal long-leg standing axis. Magnetic resonance imaging showed rupture of the PCL graft with no meniscal, chondral, or concomitant ligament injuries. Technique Description: We described a single-bundle transtibial technique with a posterior transeptal portal approach to reconstruct the PCL. We started by preparing the allograft with an internal brace augmentation and an adjustable button (Arthrex) placed on the femoral side for cortical fixation. The old semi-anatomical femoral tunnel was drilled and grafted using an allograft bone dowel (Biobank), and a new anatomic femoral tunnel was drilled inside-out. Under direct visualization via posterior transeptal portals, a new anatomic tibial tunnel was drilled posterior to the existing nonanatomic tunnel. Using a shuttle suture, the transplant was passed and fixed by an adjustable button at the femur and by two interference screws and a backup fixation using a Swive-lock anchor at the tibia (Arthrex). Results: Favorable functional and clinical outcomes with improvement of anteroposterior stability. Significant improved side-to-side differences on posterior stress radiography and improved subjective and objective clinical scores. Satisfactory outcomes with 75% of patients returned to preinjury Tegner activity scale level of function. Discussion/Conclusion: The use of the posterior transeptal portals approach protects the vital neurovascular structures and ensures proper PCL tibial tunnel placement by providing direct visualization of the tibial attachment. Allograft bone dowels facilitate PCL revision in a one-stage procedure by filling the existing semi-anatomic tunnels and allowing to drill the new anatomic tunnels without tunnel overlap. The use of the internal brace augmentation strengthens the construct to protect the graft during the revascularization and remodeling process by facilitating tissue ingrowth and incorporation. In revision surgery, backup fixation is encouraged and often essential due to the compromised bone stock. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Is posterior knee arthroscopy using posterior portals necessary for orthopedic surgeons? The latest evidence on applications and techniques.

Various uses of posterior knee arthroscopy have been shown, including all-inside repair of posterior meniscal lesions, posterior cruciate ligament (PCL) reconstruction or PCL avulsion fixation, extensile posterior knee synovectomy for pigmented villonodular synovitis or synovial chondromatosis, posterior capsular release in the setting of knee flexion contractures, and loose bodies removal. Posterior arthroscopy provides direct access to the posterior meniscal borders for adequate abrasion and fibrous tissue removal. This direct view of the knee posterior structures enables the surgeon to create a stronger biomechanical repair using vertical mattress sutures. During PCL reconstruction, posterior arthroscopy gives the surgeon proper double access to the tibial insertion site, which can result in less acute curve angles and the creation of a more anatomic tibial tunnel. Moreover, it gives the best opportunity to preserve the PCL remnant. Arthroscopic PCL avulsion fixation is more time-consuming with a larger cost burden compared to open approaches, but in the case of other concomitant intra-articular injuries, it may lead to a better chance of a return to pre-injury activities. The high learning curve and overcaution of neuromuscular injury have discouraged surgeons from practicing posterior knee arthroscopy using posterior portals. Evidence for using posterior portals by experienced surgeons suggests fewer complications. The evidence suggests toward learning posterior knee arthroscopy, and this technique must be part of the education about arthroscopy. In today's professional sports world, where the quick and complete return of athletes to their professional activities is irreplaceable, the use of posterior knee arthroscopy is necessary.

Biomechanical comparison of proximal, distal, and anatomic tibial tunnel for transtibial posterior cruciate ligament reconstruction.

No consensus has been reached on the optimal position of PCL tibial tunnel. The purpose of this study was to compare the biomechanical properties of proximal, distal and anatomic tibial tunnel in transtibial posterior cruciate ligament reconstruction. An in-vitro model of transtibial posterior cruciate ligament reconstruction was simulated using porcine tibias and bovine extensor tendons. Two models of biomechanical testing, load-to-failure loading, and cyclic loading, were performed in this study. The load-to-failure loading found that distal tibial tunnel resulted in greater ultimate load and yield load than the anatomic and proximal tunnel group (p < 0.05), whereas there were no significant differences in mean tensile stiffness among three groups (p > 0.05). The cyclic loading found no differences in the graft displacement at 250, 500, and 1000 cycles among three groups (p > 0.05). It was found that distal tibial tunnel showed superior ultimate load and yield load in load-to-failure loading testing compared with proximal and anatomic tibial tunnels, whereas no significant difference was found in terms of the mean displacement of the survived grafts in cyclic loading testing among three groups.

Freehand Anatomic Transtibial Single-Bundle Anterior Cruciate Ligament Reconstruction

Creation of the femoral tunnel for single-bundle anterior cruciate ligament (ACL) reconstruction has a high rate of nonanatomic placement with the transtibial (TT) technique but yields better restoration with the anteromedial portal technique and close restoration of the anatomic femoral footprint with the outside-in technique. Modifications of the traditional (TT) technique have been described to restore the native femoral ACL footprint and to simulate double-bundle reconstruction. Modified TT techniques try to capture the anatomic femoral footprint through an anatomic tibial tunnel. In the technique described in this article, the anatomic femoral footprint is drilled first by the use of a 2.5-mm Kirschner wire through the parapatellar anteromedial portal, making an angle 30° to the sagittal plane and 20° to the horizontal plane. The wire is drilled while the knee is hyperflexed and then withdrawn from outside until its distal end reaches the intercondylar notch. The wire is then advanced in an antegrade manner while the knee is flexed 90° until it reaches the center of the marked tibial footprint. The angle of knee flexion may be slightly increased or decreased around 90° with or without slight internal rotation to capture the anatomic tibial footprint. The procedure is completed as a TT single-bundle ACL reconstruction.

An Anatomically Placed Tibial Tunnel does not Completely Surround a Simulated PCL Reconstruction Graft in the Proximal Tibia.

It is hypothesized that anatomic tunnel placement will create tunnels with violation of the posterior cortex and subsequently an oblique aperture that is not circumferentially surrounded by bone. In this article, we aimed to characterize posterior cruciate ligament (PCL) tibial tunnel using a three-dimensional (3D) computed tomography (CT) model. Ten normal knee CTs with the patella, femur, and fibula removed were used. Simulated 11 mm PCL tibial tunnels were created at 55, 50, 45, and 40 degrees. The morphology of the posterior proximal tibial exit was examined with 3D modeling software. The length of tunnel not circumferentially covered (cortex violation) was measured to where the tibial tunnel became circumferential. The surface area and volume of the cylinder both in contact with the tibial bone and that not in contact with the tibia were determined. The percentages of the stick-out length surface area and volume not in contact with bone were calculated. The mean stick-out length of uncovered graft at 55, 50, 45, and 40 degrees were 26.3, 20.5, 17.3, and 12.7 mm, respectively. The mean volume of exposed graft at 55, 50, 45, and 40 degrees were 840.8, 596.2, 425.6, and 302.9 mm3, respectively. The mean percent of volume of exposed graft at 55, 50, 45, and 40 degrees were 32, 29, 25, and 24%, respectively. The mean surface of exposed graft at 55, 50, 45, and 40 degrees were 372.2, 280.4, 208.8, and 153.3 mm2, respectively. The mean percent of surface area of exposed graft at 55, 50, 45, and 40 degrees were 40, 39, 34, and 34%, respectively. Anatomic tibial tunnel creation using standard transtibial PCL reconstruction techniques consistently risks posterior tibial cortex violation and creation of an oblique aperture posteriorly. This risk is decreased with decreasing the angle of the tibial tunnel, though the posterior cortex is still compromised with angles as low as 40 degrees. With posterior cortex violation, a surgeon should be aware that a graft within the tunnel or socket posteriorly may not be fully in contact with bone. This is especially relevant with inlay and socket techniques.

Comparable Clinical and Radiologic Outcomes Between an Anatomic Tunnel and a Low Tibial Tunnel in Remnant-Preserving Posterior Cruciate Ligament Reconstruction.

Background:There is currently no consensus on the optimal placement of the tibial tunnel for remnant-preserving posterior cruciate ligament (PCL) reconstruction.Purpose/Hypothesis:The purpose of this study was to compare the clinical and radiologic outcomes of remnant-preserving PCL reconstruction using anatomic versus low tibial tunnels. We hypothesized that the outcomes of low tibial tunnel placement would be superior to those of anatomic tibial tunnel placement at the 2-year follow-up after remnant-preserving PCL reconstruction.Study Design:Cohort study; Level of evidence, 3.Methods:We retrospectively reviewed the data for patients who underwent remnant-preserving PCL reconstruction between March 2011 and January 2018 with a minimum follow-up of 2 years (N = 63). On the basis of the tibial tunnel position on postoperative computed tomography, the patients were divided into those with anatomic placement (group A; n = 31) and those with low tunnel placement (group L; n = 32). Clinical scores (International Knee Documentation Committee subjective score, Lysholm score, and Tegner activity level), range of motion, complications, and stability test outcomes at follow-up were compared between the 2 groups. Graft signal on 1-year follow-up magnetic resonance imaging scans was compared between 22 patients in group A and 17 patients in group L.Results:There were no significant differences between groups regarding clinical scores or incidence of complications, no between-group differences in posterior drawer test results, and no side-to-side difference on Telos stress radiographs (5.2 ± 2.9 mm in group A vs 5.1 ± 2.8 mm in group L; P = .900). Postoperative 1-year follow-up magnetic resonance imaging scans showed excellent graft healing in both groups, with no significant difference between them.Conclusion:The clinical and radiologic outcomes and complication rate were comparable between anatomic tunnel placement and low tibial tunnel placement at 2-year follow-up after remnant-preserving PCL reconstruction. The findings of this study suggest that both tibial tunnel positions are clinically feasible for remnant-preserving PCL reconstruction.

Lower Tibial Tunnel Placement in Isolated Posterior Cruciate Ligament Reconstruction: Clinical Outcomes and Quantitative Radiological Analysis of the Killer Turn.

Background:The “killer turn” effect after posterior cruciate ligament (PCL) reconstruction is a problem that can lead to graft laxity or failure. Solutions for this situation are currently lacking.Purpose:To evaluate the clinical outcomes of a modified procedure for PCL reconstruction and quantify the killer turn using 3-dimensional (3D) computed tomography (CT).Study design:Case series; Level of evidence, 4.Methods:A total of 15 patients underwent modified PCL reconstruction with the tibial aperture below the center of the PCL footprint. Next, 2 virtual tibial tunnels with anatomic and proximal tibial apertures were created on 3D CT. All patients were assessed according to the Lysholm score, International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, Tegner score, side-to-side difference (SSD) in tibial posterior translation using stress radiography, and 3D gait analysis.Results:The modified tibial tunnel showed 2 significantly gentler turns (superior, 109.87° ± 10.12°; inferior, 151.25° ± 9.07°) compared with those reconstructed with anatomic (91.33° ± 7.28°; P < .001 for both comparisons) and proximal (99° ± 7.92°; P = .023 and P < .001, respectively) tibial apertures. The distance from the footprint to the tibial aperture was 16.49 ± 3.73 mm. All patient-reported outcome scores (mean ± SD) improved from pre- to postoperatively: Lysholm score, from 46.4 ± 18.87 to 83.47 ± 10.54 (P < .001); Tegner score, from 2.47 ± 1.85 to 6.07 ± 1.58 (P < .001); IKDC sports activities score, from 19 ± 9.90 to 33.07 ± 5.35 (P < .001); and IKDC knee symptoms score, from 17.87 ± 6.31 to 25.67 ± 3.66 (P < .001). The mean SSD improved from 9.15 ± 2.27 mm preoperatively to 4.20 ± 2.31 mm postoperatively (P < .001). The reconstructed knee showed significantly more adduction (by 1.642°), less flexion (by 1.285°), and more lateral translation (by 0.279 mm) than that of the intact knee (P < .001 for all).Conclusion:Lowering the tibial aperture during PCL reconstruction reduced the killer turn, and the clinical outcomes remained satisfactory. However, SSD and clinical outcomes were similar to those of previously described techniques using an anatomic tibial tunnel.

Placement of an anatomic tibial tunnel significantly improves the medial meniscus posterior extrusion at 90° of knee flexion following medial meniscus posterior root pullout repair.

The purpose of this study was to evaluate the influence of tibial tunnel position in pullout repair for a medial meniscus (MM) posterior root tear (MMPRT) on postoperative MM extrusion. Thirty patients (median age 63years, range 35-72years) who underwent transtibial pullout repairs for MMPRTs were included. Three-dimensional computed tomography images of the tibial surface were evaluated using a rectangular measurement grid for assessment of tibial tunnel position and MM posterior root attachment. Preoperative and postoperative MM medial extrusion (MMME) and posterior extrusion (MMPE) at 10° and 90° knee flexion were measured using open magnetic resonance imaging. Tibial tunnel centers were located more anteriorly and more medially than the anatomic center (median distance 5.8mm, range 0-9.3mm). The postoperative MMPE at 90° knee flexion was significantly reduced after pullout repair, although there was no significant reduction in MMME or MMPE at 10° knee flexion after surgery. In the correlation analysis of the displacement between the anatomic center to the tibial tunnel center and improvements in MMME, and MMPE at 10° and 90° knee flexion, there was a significant positive correlation between percentage distance and improvement of MMPE at 90° knee flexion. This study demonstrated that the nearer the tibial tunnel position to the anatomic attachment of the MM posterior root, the more effective the reduction in MMPE at 90° knee flexion. Our results emphasize that an anatomic tibial tunnel should be created in the MM posterior root to improve the postoperative MMPE and protect the articular cartilage in a knee flexion position. Placement of an anatomic tibial tunnel significantly improves the MMPE at 90° of knee flexion after MM posterior root pullout repair. IV.

Effects of the tibial tunnel position on knee joint stability and meniscal contact pressure after double-bundle anterior cruciate ligament reconstruction

BackgroundTo investigate the effect of the tibial tunnel position on knee stability and the maximum contact area and peak contact pressure on the menisci after double-bundle anterior cruciate ligament (ACL) reconstruction. MethodsTen human knee specimens (mean age: 74.1 ± 15.8 years) were used in this study. The anterior tibial loading test was conducted using a material testing machine at 30°, 60°, and 90° of knee flexion, with the anterior tibial translation (ATT) and the maximum contact area and peak contact pressure on the menisci measured. Outcome measures were compared between the following groups: 1) intact ACL (intact group); 2) anatomical tibial tunnel position (anatomical group) and 3) posterior tibial tunnel position (posterior group) with double-bundle reconstruction, and 4) ACL-deficient (deficient group). ResultsIn response to a 100 N anterior tibial load, the ATT was greater for the posterior and ACL-deficient groups compared to that in the intact group. The normalized maximum contact area of the medial meniscus significantly decreased for the posterior group compared to that in the intact group. The normalized peak contact pressure on the medial meniscus increased in all groups compared to that in the intact group, but with no between-group differences in pressure applied to the lateral meniscus. ConclusionsATT and contact pressure on the medial meniscus increased, concomitant with a decrease in contact area of the medial meniscus, as the position of the tibial tunnel position moved towards a posterior position.

Revision of Failed-Posterior Cruciate Ligament (PCL) Reconstruction Due To Tibial Tunnel Misplacement: A Case Report

Objectives:Posterior cruciate ligament (PCL) reconstruction failure is a rare condition found. The failure caused by some factors, including improper graft tunnel placement. The proper tibial tunnel placement in PCL reconstruction is still controversial. To have an anatomical tunnel is essential to decrease the risk of failure. The use of PCL jig only to guide the direction of the tibial tunnel may not always give good results.Case presentation:We report a case of a 29-year-old male with a total rupture of ACL and PCL that underwent reconstruction for both ligaments. We found the failure of the PCL graft 2 years after the surgery was related to the tibial tunnel placement which was placed not in proper anatomical site. We performed revision PCL surgery with a transseptal portal technique to ensure the tibial tunnel is placed inappropriate position.Result:The cause of failure was associated with the miss position of the tibial tunnel. The tibial tunnel performed in previous surgery was too anterior than the anatomical footprint. This condition might be caused by a surgical technique that depending only on PCL jig to guide the tibial tunnel direction and location. We performed a transseptal portal technique to get better visualization on the posterior aspect of the knee to achieve the proper direction of the tibial tunnel.Conclusion:The use of PCL jig as the only tool for guiding tibial tunneling should be avoided. An additional tool such as a transseptal portal is required to ensure the proper anatomical tibial tunnel to achieve good PCL graft placement.

Lateral location of the tibial tunnel increases lateral meniscal extrusion after anatomical single-bundle anterior cruciate ligament reconstruction

IntroductionThe tibial footprint of the anterior cruciate ligament (ACL) overlaps with the anterior lateral meniscal root (ALMR), and there is a possibility that an anatomical tibial tunnel reaming might damage the attachment of ALMR. The aim of this study was to investigate the relationship between tibial tunnel location and lateral meniscal extrusion (LME) after anatomical single-bundle ACL reconstruction.MethodsA prospectively collected database and associated intraoperative findings for 153 patients undergoing primary anatomical ACL reconstruction between October 2014 and July 2016 were investigated. Those cases with no meniscal injury seen at surgery and meeting the criteria (52/153) were included. Tibial plateau length (TPL), width (TPW), tibial tunnel location and LME were evaluated from postoperative high-resolution MRI. The location of the centre of the tibial tunnel was evaluated by the position relative to the medial tibial eminence with two measures, the medial–lateral distance (MLD) and anterior–posterior distance. These measures were expressed as a percentage of the TPW and TPL, respectively. The LME was also expressed as a percentage of TPW and correlated with tibial tunnel location.ResultsThere was a positive correlation between percentage of LME (%LME) and percentage of MLD (%MLD) (r=0.478; p<0.001). Applying receiver operating characteristic analysis, we determined that a cut-off value of 4 %MLD was significant. The mean percentage of LME was 1.20 for >4 %MLD, compared with 0.17 for ≤4 %MLD (p<0.001). No significant correlation was found between %LME and clinical outcomes at 1-year follow-up.ConclusionLateral location of the tibial tunnel increases the rate of LME after single-bundle ACL reconstruction.Level of evidenceLevel IV, Case series.

Mediolateral Differences of Proteoglycans Distribution at the ACL Tibial Footprint: Experimental Study of 16 Cadaveric Knees.

This study aimed to identify the staining pattern of ACL attachment blended with cartilage of the medial tibial plateau at the tibial insertion and histologically characterize the tibial footprint. Sixteen fresh frozen cadaveric knees (mean age: 52.0 ± 6.2 years) were used for this study. The specimens were bisected in the coronal plane, in accordance with the fiber orientation of the ACL tibial attachment. Adjacent sections were then stained with hematoxylin and eosin (H&E) to observe the morphology of the ACL insertion and with fast green and Safranin-O protocols to evaluate for collagen and proteoglycans (PG). The insertion area on the tibial footprint was divided into five zones in the medial to lateral direction, which was determined by division of the section from most prominent medial tibial spine to most lateral margin of ACL attachment. Then rectangular area with a vertical length that is twice the width of respective five zones was set. Stained areas of all images were quantified positively by using ImageJ software, and the value for staining area measured was defined in percentage by multiplying whole image area by 100. The mean proportion of Safranin-O staining is significantly greater nearer to the medial tibial spine (59% in zone 1, 32% in zone 2, 13% in zone 3, 13% in zone 4, and 4% in zone 5, P < 0.001). The medial section of the tibial insertion area grew in size and increased in PG staining with more densely organized collagen arrangement with more fibrocartilage cells. The ACL tibial insertion showed a medially eccentric staining pattern by histological evaluation of the ACL attachment to cartilage. Our histological results of the eccentric biomaterial property in the medial tibial spine of ACL insertion area can be considered in making a more functional anatomic tibial tunnel placement.

Comparison of Tibial Tunnel Techniques in Posterior Cruciate Ligament Reconstruction: C-Arm Versus Anatomic Fovea Landmark

PCL fovea landmark technique might be an alternative method to the fluoroscopic imaging technique for locating the anatomic tibial tunnel during trans-tibial PCL reconstruction. Tibial insertion of the posterior cruciate ligament (PCL) is in the posterior half of the PCL fovea, or that the center of the PCL working fibers was 7 mm anterior to the posterior cortex. Intraoperative fluoroscopic images are usually used for the creation of the tibial tunnel during trans-tibial PCL reconstruction. However, intraoperative fluoroscopic identification of the tibial insertion area of the PCL is often impaired by tibial rotation and overlapping anatomic structures. Therefore, the definition of reliable, arthroscopically identificable anatomic landmarks would be of great value for proper positioning of the tibial guide pin in arthroscopic trans-tibial PCL reconstruction. During our trans-tibial PCL reconstruction, a trans-septal portal is made just behind the PCL fibers and the margin of the PCL fovea can be palpated with the tip of the tibial guide. The purpose of this study was to evaluate the accuracy of the posterior cruciate ligament (PCL) fovea landmark against conventional fluoroscopic pin placement retrospectively using three-dimensional computed tomography (3D CT). Our hypothesis was that accurate tibial tunnel preparation would be possible without intraoperative fluoroscopic imaging using reliable anatomic landmarks of the PCL fovea. This retrospective comparison focused on the tibial tunnel locations determined in consecutive 26 patients using fluoroscopic imaging technique (group I) and in consecutive 23 patients using the PCL fovea landmark technique without the help of the fluoroscopy (group II) for the tibial tunnel formation. The 3D surface modeled tomography (CT) images that appropriately located the position of PCL fovea on the tibial plateau were used. Ratios between total length of the fovea and length of the tunnel center from the medial border (coronal) and posterior edge (sagittal) were evaluated. The ratios between sagittal tunnel length and total sagittal length for groups I and II were 35.4 ± 12.2 % and 44.1 ± 23.1 %, respectively (p=0.07). The ratios between the coronal tunnel lengths and total coronal lengths for groups I and II were 47.3 ± 9.2 % and 57.3 ± 18.1 %, respectively: group II showed more laterally positioned tibial tunnel than did group I (p=0.03). More laterally located tibial tunnel was produced using a PCL fovea landmark technique. However, the differences in centers were small and probably not clinically relevant. Therefore, PCL fovea landmark technique might be an alternative method to the fluoroscopic imaging technique for locating the anatomic tibial tunnel during trans-tibial PCL reconstruction.

Anatomic Anterior Cruciate Ligament Reconstruction: The Use of the Anterior Horn of the Lateral Meniscus as a Guide to Tibial Tunnel Placement

Anatomic anterior cruciate ligament reconstruction has been shown to reduce the risk of graft failure and to improve patient-related clinical outcomes. The posterior border of the anterior horn of the lateral meniscus is a useful marker for anatomic tibial tunnel placement. Assessment of a preoperative magnetic resonance imaging scan can allow surgical planning of tibial tunnel placement to allow for anatomic, patient-specific tibial tunnel placement during anatomic anterior cruciate ligament reconstruction. We present this technique to show how to use the posterior border of the anterior horn of the lateral meniscus clinically.

Does Proximal-Distal Tibial Tunnel Placement for PCL Reconstruction Matter?

The purpose of this study was to investigate the biomechanical effects of proximal-distal tibial tunnel placement on posterior laxity in PCL reconstruction. Eighteen human cadaveric knees were studied, consisting of nine matched pairs. Transtibial PCL reconstruction was performed using a simulated arthroscopic technique. The native PCL was resected, and Achilles tendon autografts were used for PCL reconstruction. The specimens were divided into two groups based on tibial tunnel placement: 1) anatomic tunnel and 2) non-anatomic tunnel. The anatomic tibial tunnel was placed at the footprint of the PCL, 1 cm distal to the joint line, while the non-anatomic tibial tunnel was placed more proximal to this, at the joint line. A 150-N cyclic posterior tibial load was applied using a Materials Testing System (MTS) machine at 0⁰, 30⁰, 60⁰, and 90⁰ of knee flexion. In 10 specimens, a static 250-N posterior tibial load was applied at 90⁰ of knee flexion. Posterior tibial translation in the sagittal plane was recorded. A Mann-Whitney U test was used to compare posterior tibial translation between the two groups. Statistical significance was set defined as p <0.05. With application of a 150-N posteriorly directed cyclic force, the anatomic tunnel group demonstrated significantly less posterior tibial translation than the non-anatomic tunnel group at 0⁰, 30⁰, 60⁰, and 90⁰ of knee flexion (p <0.05). The anatomic tunnel group also demonstrated significantly less posterior tibial translation than the non-anatomic tunnel group at 90⁰ with a static 250-N posteriorly directed force applied (p <0.05). Anatomic distal tibial tunnel placement recreating the tibial origin of the PCL provided significantly greater restraint to posterior tibial translation than proximal non-anatomic tunnel placement. We recommend careful placement of an anatomic distal tibial tunnel during PCL reconstruction for avoidance of posterior laxity.

Nonanatomic Tibial Tunnel Placement for Single-Bundle Posterior Cruciate Ligament Reconstruction Leads to Greater Posterior Tibial Translation in a Biomechanical Model

To determine the effect of varying proximal-distal tibial tunnel placement on posterior cruciate ligament (PCL) laxity. Nine matched pairs (18 total) of cadaveric knees (mean age 79.3 years, range 60 to 89), were studied. The specimens from each pair were randomly divided into 2 groups based on tibial tunnel placement: (1) anatomic tunnel and (2) proximal nonanatomic tunnel. A 150-N cyclic posterior tibial load was applied using a Materials Testing System machine at 0°, 30°, 60°, and 90° of knee flexion. Each specimen completed 50 cycles at a rate of 0.2 Hz at each knee flexion angle. In 10 specimens, a static 250-N posterior tibial load was applied at 90° of knee flexion. Posterior tibial translation was recorded. Load to failure for all specimens was recorded. With application of a 150-N posteriorly directed cyclic force, the anatomic tunnel group had significantly less posterior tibial translation (millimeters, mean [standard deviation (SD)]) than the proximal nonanatomic tunnel group at 0°, 30°, 60°, and 90° of knee flexion: 1.1 (0.3) v 1.5 (0.4), P= .031; 1.1 (0.6) v 2.2 (0.9), P= .019; 0.9 (0.4) v 2.0 (0.6), P= .001; 0.9 (0.6) v 2.9 (0.7), P < .001, respectively. The anatomic tunnel group also demonstrated significantly less posterior tibial translation (millimeters, mean [SD]) than the nonanatomic tunnel group at 90° with a static 250-N posteriorly directed force applied (P <.05): 2.3 (1.3) v 6.1 (2.3), P= .016. Four pairs were excluded from the 250-N results because of prior load to failure testing. Anatomic tibial tunnel placement re-creating the tibial origin of the PCL results in significantly less posterior tibial translation than proximal nonanatomic tibial tunnel placement. Correct placement of the tibial tunnel during PCL reconstruction is essential for avoidance of posterior laxity. Anatomic tibial tunnel placement during PCL reconstruction may ensure a more stable reconstruction.

The Lateral Meniscus as a Guide to Anatomical Tibial Tunnel Placement During Anterior Cruciate Ligament Reconstruction.

Purpose: The aim of the study is to show, on an MRI scan, that the posterior border of the anterior horn of the lateral meniscus (AHLM) could guide tibial tunnel position in the sagittal plane and provide anatomical graft position.Method:One hundred MRI scans were analysed with normal cruciate ligaments and no evidence of meniscal injury. We measured the distance between the posterior border of the AHLM and the midpoint of the ACL by superimposing sagittal images.Results:The mean distance between the posterior border of the AHLM and the ACL midpoint was -0.1mm (i.e. 0.1mm posterior to the ACL midpoint). The range was 5mm to -4.6mm. The median value was 0.0mm. 95% confidence interval was from -0.5 to 0.3mm. A normal, parametric distribution was observed and Intra- and inter-observer variability showed significant correlation (p<0.05) using Pearsons Correlation test (intra-observer) and Interclass correlation (inter-observer).Conclusion:Using the posterior border of the AHLM is a reproducible and anatomical marker for the midpoint of the ACL footprint in the majority of cases. It can be used intra-operatively as a guide for tibial tunnel insertion and graft placement allowing anatomical reconstruction. There will inevitably be some anatomical variation. Pre-operative MRI assessment of the relationship between AHLM and ACL footprint is advised to improve surgical planning.Level of Evidence:Level 4.

Comparison of Tibial Tunnel Techniques in Posterior Cruciate Ligament Reconstruction: C-Arm Versus Anatomic Fovea Landmark

To evaluate the accuracy of the posterior cruciate ligament (PCL) fovea landmark against conventional fluoroscopic pin placement retrospectively using 3-dimensional computed tomography (3D CT). This retrospective comparison focused on the tibial tunnel locations determined in consecutive 26 patients using the fluoroscopic imaging technique (group I) and in consecutive 23 patients using the PCL fovea landmark technique without the help of thefluoroscopy (group II) for tibial tunnel formation. The 3D surface-modeled CT images that appropriately located the position of the PCL fovea on the tibial plateau were used. Ratios between total length of the fovea and length of the tunnelcenter from the medial border (coronal) and posterior edge (sagittal) were evaluated. The ratios between sagittal tunnel length and total sagittal length for groups I and II were 35.4% ± 12.2% and 44.1% ± 23.1%, respectively (P= .07). The ratios between the coronal tunnel lengths and total coronal lengths for groups I and II were 47.3% ± 9.2% and 57.3% ± 18.1%, respectively: group II showed a more laterally positioned tibial tunnel than did group I (P= .03). A more laterally located tibial tunnel was produced using the PCL fovea landmark technique. However, the differences in centers were small and probably not clinically relevant. Therefore, the PCL fovea landmark technique might be an alternative method to the fluoroscopic imaging technique for locating the anatomic tibial tunnel during transtibial PCL reconstruction. Level III, retrospective comparative study.

Inside-Out Antegrade Tibial Tunnel Drilling Through the Posterolateral Portal Using a Flexible Reamer in Posterior Cruciate Ligament Reconstruction

Posterior cruciate ligament (PCL) reconstruction using the transtibial drilling or arthroscopic tibial-inlay technique has a risk of injury to the popliteal neurovascular bundle because a pin is drilled anterior to posterior. Intraoperative fluoroscopy is used to decrease the risk of neurovascular injury. In addition, graft passage in the transtibial technique may be problematic because of a sharp turn when placing the graft into the tibial tunnel, which may damage graft fibers. In the surgical technique described in this report, the posteromedial portal is used for visualization and the posterolateral portal is used for debridement of the PCL tibial footprint and the synovial fold closest to the PCL. A curved guide is placed from the posterolateral portal to the tibial footprint, and a flexible pin is drilled across the tibia. The tibial tunnel is then created using a flexible reamer under direct visualization up to the desired length, and a graft can be positioned in the tibial tunnel through the posterolateral portal. This technique has the potential advantages of decreasing the risk of injury to the popliteal neurovascular bundle (use of anteriorly directed, inside-out drilling), avoiding a sharp turn during graft passage, and allowing accurate and anatomic tibial tunnel placement without intraoperative fluoroscopy.