Anterior Cruciate Ligament Tunnel Research Articles

Variability in ACL Tunnel Placement

Background: Multicenter and multisurgeon cohort studies on anterior cruciate ligament (ACL) reconstruction are becoming more common. Minimal information exists on intersurgeon and intrasurgeon variability in ACL tunnel placement. Purpose/Hypothesis: The purpose of this study was to analyze intersurgeon and intrasurgeon variability in ACL tunnel placement in a series of The Multicenter Orthopaedic Outcomes Network (MOON) ACL reconstruction patients and in a clinical cohort of ACL reconstruction patients. The hypothesis was that there would be minimal variability between surgeons in ACL tunnel placement. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Seventy-eight patients who underwent ACL reconstruction by 8 surgeons had postoperative imaging with computed tomography, and ACL tunnel location and angulation were analyzed using 3-dimensional surface processing and measurement. Intersurgeon and intrasurgeon variability in ACL tunnel placement was analyzed. Results: For intersurgeon variability, the range in mean ACL femoral tunnel depth between surgeons was 22%. For femoral tunnel height, there was a 19% range. Tibial tunnel location from anterior to posterior on the plateau had a 16% range in mean results. There was only a small range of 4% for mean tibial tunnel location from the medial to lateral dimension. For intrasurgeon variability, femoral tunnel depth demonstrated the largest ranges, and tibial tunnel location from medial to lateral on the plateau demonstrated the least variability. Overall, surgeons were relatively consistent within their own cases. Using applied measurement criteria, 85% of femoral tunnels and 90% of tibial tunnels fell within applied literature-based guidelines. Ninety-one percent of the axes of the femoral tunnels fell within the boundaries of the femoral footprint. Conclusion: The data demonstrate that surgeons performing ACL reconstructions are relatively consistent between each other. There is, however, variability of average tunnel placement up to 22% of mean condylar depth, likely reflecting the difference in individual surgeons’ preferred tunnel locations. Individual surgeons are relatively consistent in their cases of ACL tunnels.

Intertunnel Relationships in Combined Anterior Cruciate Ligament and Posterolateral Corner Reconstruction

Background: Combined anterior cruciate ligament (ACL) and posterolateral corner (PLC) injuries are relatively common, and tunnel convergence could occur in combined ACL and PLC reconstruction. Purpose: This study sought to elucidate the ranges of angles and distances of lateral collateral ligament (LCL) and popliteus tendon (PT) femoral tunnels that do not violate the intercondylar notch distally and ACL tunnels proximally during combined ACL and PLC reconstruction. Study Design: Descriptive laboratory study. Methods: Three-dimensional anatomic knee models were developed using customized software from computed tomography images of 14 patients at 0°, 90°, and 120° of flexion. Single-bundle (SB) and double-bundle (DB) ACL tunnels using the transtibial method for anteromedial bundles and the anteromedial portal method for posterolateral bundles were created. The ranges of safe angles and distances were measured at 10° and 20° posterior, neutral (0°), and 10° and 20° anterior on the horizontal plane relative to the transepicondylar axis from the isometric LCL and PT femoral insertions. The SB ACL reconstruction using the accessory medial portal and LCL reconstruction using the anatomic footprint were also analyzed. Results: Distal and proximal angles from insertions of the LCL and PT, not violating the intercondylar notch or the ACL tunnels, increased as the LCL or PT headed from a posterior to anterior direction. Safe distances from the LCL and PT femoral insertions were approximately over 35 mm distally and 30 mm proximally. For SB ACL reconstruction using the accessory medial portal, safe angles were larger proximally than those of SB ACL reconstruction using the transtibial technique. For LCL reconstruction using the anatomic footprint, proximal angles were significantly smaller than those of the isometric LCL. Conclusion: Considering the relationship between the LCL and PT tunnels and fixation strength, tunneling will be safe when the LCL and PT are positioned at an angle of approximately 20° anterior and 10° proximal to the transepicondylar axis. Clinical Relevance: These results will help to reduce the incidence of tunnel convergence in combined ACL and PLC reconstructions.

Medial portal technique for single-bundle anatomical Anterior Cruciate Ligament (ACL) reconstruction

The aim of the paper is to describe the medial portal technique for anatomical single-bundle anterior cruciate ligament (ACL) reconstruction. Placement of an ACL graft within the anatomical femoral and tibial attachment sites is critical to the success and clinical outcome of ACL reconstruction. Non-anatomical ACL graft placement is the most common technical error leading to recurrent instability following ACL reconstruction. ACL reconstruction has commonly been performed using a transtibial tunnel technique in which the ACL femoral tunnel is drilled through a tibial tunnel positioned in the posterior half of the native ACL tibial attachment site. ACL reconstruction performed using a transtibial tunnel technique often results in a vertical ACL graft, which may fail to control the combined motions of anterior tibial translation and internal tibial rotation which occur during the pivot-shift phenomenon. The inability of a vertically oriented ACL graft to control these combined motions may result in the patient experiencing continued symptoms of instability due to the pivot-shift phenomenon. The medial portal technique in which the ACL femoral tunnel is drilled through an anteromedial or accessory anteromedial portal allows consistent anatomical ACL tunnel placement. This paper describes the advantages of the medial portal technique, indications for the technique, patient positioning, proper portal placement, anatomical femoral and tibial tunnel placement, graft tensioning and fixation.

Femoral Tunnel Drilling Angles for the Posterolateral Corner in Multiligamentary Knee Reconstructions: Computed Tomography Evaluation in a Cadaveric Model

The goal of this study was to determine the best angle at which to drill the femoral tunnels of the popliteus tendon (PT) and fibular collateral ligament (FCL) in combined reconstructive procedures so as to avoid either short tunnels or tunnel collisions with the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) femoral tunnels. Eight cadaveric knees were studied. ACL/PCL femoral tunnels were arthroscopically drilled. PT and FCL tunnels were drilled at 0° and 30° axial and coronal angulations. They were scanned by computed tomography todocument relations of the PT and FCL tunnels to the intercondylar notch and ACL/PCL tunnels. A minimum tunnel length of 25 mm was required. Drilling the PT tunnel at 0° axial angulation was associated with an increased risk of tunnel collision with the ACL (P < .001). Interference with the PCL tunnel can be avoided only if the K-wire guiding the PT tunnel is drilled with 30° coronal angulations (P < .001). The minimum tunnel length of the PT could be obtained only with both axial and coronal angulations of 30° (P= .003). Sufficient tunnel lengths of the FCL were obtained at all angulations evaluated (P= .036). However, only the tunnels drilled at 30° axial and 0° coronal angulations did not collapse with the ACL tunnels (P < .001). No intersections between FCL and PT tunnels were observed. When posterolateral reconstructions are performed in combination with concomitant anterior and posterior cruciate procedures, PT tunnels should be drilled at 30° axial and 30° coronal angulations. FCL tunnels should be drilled at 30° axial and 0° coronal angulations. These angulations should minimize such potential complications as short tunnels or collisions with the ACL/PCL tunnels. Specific drilling angles are necessary to avoid short tunnels or collisions between the drilled tunnels when FCL and PT femoral tunnels are performed in multiligament knee reconstructions.

Arthroscopic Agreement Among Surgeons on Anterior Cruciate Ligament Tunnel Placement

Background: Little is known about surgeon agreement and accuracy using arthroscopic evaluation of anterior cruciate ligament (ACL) tunnel positioning. Purpose: To investigate agreement on ACL tunnel position evaluated arthroscopically between operating surgeons and reviewing surgeons. We hypothesized that operating and evaluating surgeons would characterize tunnel positions significantly differently. Study Design: Controlled laboratory study. Methods: Twelve surgeons drilled ACL tunnels on 72 cadaveric knees using transtibial (TT), medial portal (MP), or 2-incision (TI) techniques and then completed a detailed assessment form on tunnel positioning. Then, 3 independent blinded surgeon reviewers each arthroscopically evaluated tunnel position and completed the assessment form. Statistical comparisons of tunnel position evaluation between operating and reviewing surgeons were completed. Three-dimensional (3D) computed tomography (CT) scans were performed and compared with arthroscopic assessments. Arthroscopic assessments were compared with CT tunnel location criteria. Results: Operating surgeons were significantly more likely to evaluate femoral tunnel position (92.6% vs 69.2%; P = .0054) and femoral back wall thickness as “ideal” compared with reviewing surgeons. Tunnels were judged ideal by reviewing surgeons more often when the TI technique was used compared with the MP and TT techniques. Operating surgeons were more likely to evaluate tibial tunnel position as ideal (95.5% vs 57.1%; P < .0001) and “acceptable” compared with reviewers. The ACL tunnels drilled using the TT technique were least likely to be judged as ideal on the tibia and the femur. Agreement among surgeons and observers was poor for all parameters (κ = −0.0053 to 0.2457). By 3D CT criteria, 88% of femoral tunnels and 78% of tibial tunnels were placed within applied criteria. Conclusion: Operating surgeons are more likely to judge their tunnels favorably than observers. However, independent surgeon reviewers appear to be more critical than results of 3D CT imaging measures. When subjectively evaluated arthroscopically, the TT technique yields more subjectively poorly positioned tunnels than the TI and MP techniques. Surgeons do not agree on the ideal placement for single-bundle ACL tunnels. Clinical Relevance: This study demonstrates that surgeons do not currently uniformly agree on ideal single-bundle tunnel placement and that the TT technique may yield more poorly placed tunnels.

Reliability of Tunnel Measurements and the Quadrant Method Using Fluoroscopic Radiographs After Anterior Cruciate Ligament Reconstruction

Background: Anterior cruciate ligament (ACL) reconstruction tunnel placement is often evaluated by radiographs. This study examines the interobserver reliability of various radiographic measurements of ACL tunnels. Hypothesis: When ideal radiographic views are obtained, the interobserver reliability of the measurements among experienced surgeons would be good to excellent. Study Design: Descriptive laboratory study. Methods: Tunnels for single-bundle ACL reconstruction were drilled and filled with metal interference screws or a tibial reamer on 73 cadaveric knees. Ideal fluoroscopic radiographs were obtained. Three independent reviewers performed 18 measurements including a modification of the grid method. For the grid method analysis, reviewers fit a 16 × 12 grid to the lateral knee radiograph, and the center of the femoral tunnel was marked. Interobserver reliability of the measurements was performed using intraclass correlation coefficients (ICCs). A precision grouping analysis was performed for the grid measurements to calculate the mean radius and standard deviation grouping distances. Results: The ICCs were excellent (>.75) for the tibial tunnel angles and tunnel measurements, the clock face measurement, and the Aglietti et al and Jonsson et al measurements. The ICCs were good (.4-.75) for an estimation of graft impingement, Harner et al measurements, and notch height. The mean radius for grid measurements was 0.6 ± 0.4 units (range, 0-2.36 units), with each unit being 1 box in the 16 × 12 grid. When a circle was constructed with a 1.3-unit radius, 95% of the 3 surgeons’ measurements would be included in the area of that circle. Conclusion: Reliability of ACL tunnel measurements was good to excellent under ideal circumstances for the majority of measurements. The modified grid method demonstrated very acceptable reliability. Clinical Relevance: Measurements with good to excellent reliability can be used to evaluate ACL tunnel placement when ideal radiographic views are obtained.

Do Large-Diameter Hamstring Grafts in Young Patients Prevent Knee Osteoarthritis After ACL Reconstruction?

Do Large-Diameter Hamstring Grafts in Young Patients Prevent Knee Osteoarthritis After ACL Reconstruction?

Anatomic Landmarks Utilized for Physeal-Sparing, Anatomic Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament (ACL) injury and reconstruction in the skeletally immature patient are becoming more common. The purpose of this study was to develop a reproducible anatomic ACL reconstruction technique, based on intra-articular and extra-articular landmarks, that reliably produces a femoral tunnel of adequate length and diameter while avoiding the distal femoral physis. Magnetic resonance images (MRIs) of one hundred and eighty-eight children (age range, six to seventeen years) were evaluated. Two extra-articular landmarks, the femoral insertion of the popliteus tendon and the lateral femoral epicondyle, and one intra-articular landmark, the central portion of the femoral footprint of the ACL, were identified. Computer software was used to plot these landmarks in all three planes and to draw lines representing two potential femoral tunnels. The first line connected the center of the ACL femoral footprint with the insertion of the popliteus tendon, and the second connected the center of the ACL femoral footprint with the lateral femoral epicondyle. The length of each tunnel, the shortest distance from the center of each tunnel to the distal femoral physis, and the height of the lateral femoral condyle from the physis to the chondral surface and to the base of the cartilage cap were calculated. A three-dimensional MRI reconstruction was used to confirm that placement of a femoral tunnel with use of the chosen landmarks would avoid the distal femoral physis. The mean distance from the center of the preferred ACL tunnel, which connected the center of the ACL femoral footprint with the insertion of the popliteus tendon, to the distal femoral physis was 12 mm, independent of sex (p = 0.94) or age, and the shortest distance was 8 mm. The length of this proposed tunnel averaged 30.1 mm in the boys and 27.4 mm in the girls (p &lt; 0.001), and it averaged 25.4 mm at an age of six years and 29.7 mm at an age of seventeen years. The mean distance from the center of the alternative tunnel, which connected the center of the ACL femoral footprint with the lateral epicondyle, to the distal femoral physis was 8.8 mm in the boys and 8.9 mm in the girls (p = 0.55). The mean length of this alternative tunnel was 34.3 mm in the boys and 31.6 mm in the girls (p &lt; 0.001). Drilling from the center of the ACL femoral footprint to the insertion of the popliteus tendon would have resulted in a mean tunnel length of 27 to 30 mm, and it would have allowed the safe placement of a femoral tunnel at least 7 mm in diameter in a patient six to seventeen years old. The center of the ACL femoral footprint and the popliteus insertion are easily identifiable landmarks and will allow safe, reproducible, anatomic ACL reconstruction in the skeletally immature patient.

Lateral Femoral Cortical Breach During Anterior Cruciate Ligament Reconstruction: A Biomechanical Analysis

The purpose of our study was to determine whether secondary fixation is needed when lateral femoral wall breach occurs and whether the diameter of the femoral tunnel affects the cyclical and ultimate load to failure of 3 different suspensory fixation devices. Sixty fresh-frozen porcine femora were dissected to isolate the anterior cruciate ligament (ACL) footprint. Femoral ACL tunnels were then drilled at diameters of 7, 8, 9, and 10 mm. We conducted 5 separate cyclical and ultimate load testing trials, at each tunnel diameter, for 3 different cortical suspension devices. The mean load to failure decreased as the tunnel size enlarged for all 3 devices. In 7-mm tunnels, mean failure load ranged from 1,163.7 to 1,455.0 N across the 3 devices; in 8-mm tunnels, 1,154.7 to 1,643.2 N; in 9-mm tunnels, 820.8 to 1,125.21 N; and in 10-mm tunnels, 314.7 to 917.8 N. Modes of failure also varied as the tunnel sizes enlarged. The ultimate load was not different among the 3 manufacturers (P = .08), but there was a difference in the ultimate load across the 4 tunnel diameters (P < .05), except when we compared the 7-mm tunnel with the 8-mm tunnel (P = .91). With 7- and 8-mm-diameter tunnels, failure loads with each of the suspensory devices tested exceeded the documented interference screw load to failure. Our findings suggest that, for soft-tissue ACL grafts, femoral tunnels of 8 mm or less can be drilled through the lateral femoral cortex while still using a suspensory device for graft fixation. With pediatric, double-bundle, and anatomic ACL reconstructions, smaller and shorter tunnels are routinely used. Thus, breaching the lateral cortex when using suspensory fixation may increase tunnel length while still achieving stable fixation.

Comparison of Anterior Cruciate Ligament Tunnel Position and Graft Obliquity With Transtibial and Anteromedial Portal Femoral Tunnel Reaming Techniques Using High-Resolution Magnetic Resonance Imaging

Using 3-dimensional high-resolution magnetic resonance imaging (MRI), we sought to compare femoral and tibial tunnel position and resultant graft obliquity with single-bundle anterior cruciate ligament (ACL) reconstruction using transtibial (TT) or anteromedial (AM) portal femoral tunnel reaming techniques. Thirty patients were prospectively enrolled after primary, autogenous bone-patellar tendon-bone ACL reconstruction by 2 groups of high-volume, fellowship-trained sports medicine surgeons. With the TT technique, an external starting point was used to maximize graft obliquity and femoral footprint capture. By use of high-resolution MRI and imaging analysis software, bilateral 3-dimensional knee models were created, mirrored, and superimposed. Differences between centroids for each femoral and tibial insertion, as well as corresponding ACL/graft obliquity, were evaluated with paired t tests and 2-sided Mann-Whitney nonparametric tests, with P < .05 defined as significant. No significant differences were observed between groups in position of reconstructed femoral footprints. However, on the tibial side, AM centroids averaged 0.8 ± 1.9 mm anterior to native ACL centroids, whereas the TT group centered 5.23 ± 2.4 mm posterior to native ACL centroids (P < .001). Sagittal obliquity was closely restored with the AM technique (mean, 52.2° v. 53.5° for native ACL) but was significantly more vertical (mean, 66.9°) (P = .0001) for the TT group. In this clinical series, AM portal femoral tunnel reaming more accurately restored native ACL anatomy than the TT technique. Although both techniques can capture the native femoral footprint with similar accuracy, the TT technique requires significantly greater posterior placement of the tibial tunnel, resulting in decreased sagittal graft obliquity. When a tibial tunnel is drilled without the need to accommodate subsequent femoral tunnel reaming, more accurate tibial tunnel position and resultant sagittal graft obliquity are achieved. Level III, retrospective comparative study.

Anterior Cruciate Ligament Tunnel Position Measurement Reliability on 3-Dimensional Reconstructed Computed Tomography

The purpose of this study was to evaluate intraobserver and interobserver reliability of anterior cruciate ligament tunnel location measurement by use of 3-dimensional reconstructed computed tomography (CT). Three-dimensional reconstructed CT images of 31 cadaveric knees were used in this study. Twenty-one knees were operated on with a double-bundle technique, and ten knees were operated on with a single-bundle technique. Femoral tunnel location was measured with 3 methods on the medial-lateral view of the lateral femoral condyle in the strictly lateral position. Tibial tunnel location was measured in the top view of the proximal tibia. The images were evaluated independently by 2 orthopaedic surgeons. A second measurement was performed, by both testers, after a 4-week interval. The 3 methods of femoral tunnel location measurement had intraobserver intraclass correlation coefficients (ICCs) that ranged from 0.963 to 0.998 and interobserver ICCs that ranged from 0.993 to 0.999. Tibial tunnel measurement had intraobserver ICCs that varied between 0.957 and 0.998 and interobserver ICCs that varied between 0.993 and 0.996. The measurement of the anterior cruciate ligament tunnel location on 3-dimensional reconstructed CT provided excellent intraobserver and interobserver reliability. Three-dimensional reconstructed CT can be used for further studies to assess the effect of tunnel position on knee stability and patient outcomes.

The Location of Femoral and Tibial Tunnels in Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Analyzed by Three-Dimensional Computed Tomography Models

Characterization of the insertion site anatomy in anterior cruciate ligament reconstruction has recently received increased attention in the literature, coinciding with a growing interest in anatomic reconstruction. The purpose of this study was to visualize and quantify the position of anatomic anteromedial and posterolateral bone tunnels in anterior cruciate ligament reconstruction with use of novel methods applied to three-dimensional computed tomographic reconstruction images. Careful arthroscopic dissection and anatomic double-bundle anterior cruciate ligament tunnel drilling were performed with use of topographical landmarks in eight cadaver knees. Computed tomography scans were performed on each knee, and three-dimensional models were created and aligned into an anatomic coordinate system. Tibial tunnel aperture centers were measured in the anterior-to-posterior and medial-to-lateral directions on the tibial plateau. The femoral tunnel aperture centers were measured in anatomic posterior-to-anterior and proximal-to-distal directions and with the quadrant method (relative to the femoral notch). The centers of the tunnel apertures for the anteromedial and posterolateral tunnels were located at a mean (and standard deviation) of 25% +/- 2.8% and 46.4% +/- 3.7%, respectively, of the anterior-to-posterior tibial plateau depth and at a mean of 50.5% +/- 4.2% and 52.4% +/- 2.5% of the medial-to-lateral tibial plateau width. On the medial wall of the lateral femoral condyle in the anatomic posterior-to-anterior direction, the anteromedial and posterolateral tunnels were located at 23.1% +/- 6.1% and 15.3% +/- 4.8%, respectively. The proximal-to-distal locations were at 28.2% +/- 5.4% and 58.1 +/- 7.1%, respectively. With the quadrant method, anteromedial and posterolateral tunnels were measured at 21.7% +/- 2.5% and 35.1% +/- 3.5%, respectively, from the proximal condylar surface (parallel to the Blumensaat line), and at 33.2% +/- 5.6% and 55.3% +/- 5.3% from the notch roof (perpendicular to the Blumensaat line). Intraobserver and interobserver reliability was high, with small standard errors of measurement. This cadaver study provides reference data against which tunnel position in anterior cruciate ligament reconstruction can be compared in future clinical trials.

Navigation for anterior cruciate ligament surgery

Anterior cruciate ligament (ACL) reconstruction is a common and generally successful surgical procedure. Recent studies, however, have demonstrated a failure of traditional techniques to restore knee kinematics. Surgical navigation allows for an augmented three dimensional view of the surgical field and can provide quantitative feedback to supervise surgical decision-making. In addition, knee kinematics can be accurately tracked using these systems. These computer-assisted surgery systems have been proposed for refinement of tunnel positioning in ACL surgery. Navigation systems, however, are best used when clearly defined targets have been established. To date, controversy remains concerning optimal positioning of ACL tunnels; as such, it remains unclear which targets should be used for navigation. Navigation systems have become an increasingly popular tool to track intraoperative knee kinematics. Studies have demonstrated that the systems are accurate in quantifying uniplanar examinations such as the Lachman and arcs of rotation at a defined flexion angle, as well as complex multiplanar examinations such as the pivot shift. The repeatability of standardized load application, however, limits the generalizability of quantitative data. Never-the-less, these tools have proven valuable in the basic science arena and have been used to assess the time zero performance of various ACL reconstruction constructs. In the future, standardized mechanical testing devices and non-invasive tracking strategies may allow for longitudinal use of navigation systems for outcome analysis. In addition, if targets can be identified for optimal tunnel positions, navigation may become valuable in refining surgical techniques.

Mini-incision Patellar Tendon Harvest and Anterior Cruciate Ligament Reconstruction Using Critical Bony Landmarks

Graft choice remains an area of contention in anterior cruciate ligament reconstruction. Poorer cosmetic results and anterior knee pain remain a problem in the use of autologous patellar tendon grafts despite excellent clinical results when compared with autologous hamstring tendon grafts. Using a 2-incision technique to harvest the patellar tendon grafts has been shown to decrease the risk of anterior knee pain to a level comparable to hamstring tendon grafts. Proper graft tunnel placement and orientation also remain controversial with several recent researchers arguing the ability to perform an anatomic reconstruction using a conventional endoscopic transtibial technique. We will describe a relatively simple and cosmetically acceptable 2-incision technique for harvesting a bone-tendon-bone graft. In addition, we will describe the bony landmarks that should be used to ensure proper anatomic graft placement and the appropriate angles that need to be used for the tibial tunnel to drill the femoral tunnel in an anatomic position and carry out a successful endoscopic transtibial tunnel anterior cruciate ligament reconstruction.

Rectangular Tunnel Double-Bundle Anterior Cruciate Ligament Reconstruction with Bone–Patellar Tendon–Bone Graft to Mimic Natural Fiber Arrangement

We describe our current technique of anatomic, double-bundle (DB), rectangular tunnel anterior cruciate ligament (ACL) reconstruction with bone–patellar tendon–bone (BPTB) graft. This technique mimics the natural, or anatomic, arrangement of the native ACL fibers. This technique has the following advantages: (1) creation of a DB ACL reconstruction with a single BPTB graft; (2) maximization of graft–tunnel contact area; (3) containment of the tunnel apertures within the anatomic ACL attachment footprint; (4) rotational control of the graft within the tunnels during and after fixation; and (5) preservation of notch anatomy.

Tunnel Positioning of Anteromedial and Posterolateral Bundles in Anatomic Anterior Cruciate Ligament Reconstruction

Background The interest in double-bundle anterior cruciate ligament (ACL) reconstructions has recently reawakened. Hypothesis The center of the femoral posterolateral (PL) bundle and the center of the femoral anteromedial (AM) bundle are not within the same plane and change their orientation throughout passive knee flexion. Additionally, the tibial center of the AM bundle is aligned with the anterior horn of the lateral meniscus and the center of the PL bundle lies at the recommended tibial tunnel position for single-bundle ACL reconstruction reconstruction, 7 to 9 mm anterior to the posterior cruciate ligament. Study Design Descriptive laboratory study. Materials In 20 human cadaveric knees (age range, 45–87 years) the distances from the center of the AM and PL bundle to the articular cartilage were measured. Radiographic analyses were performed using the techniques of Bernard and Hertel at the femur as well as the method by Stäubli and Rauschning at the tibia. Results The center of the AM bundle was at a point 5.3 mm (± 0.7) from the roof of the notch and 5.7 mm (± 0.5) from the intercondylar line. The center of the PL bundle is located at 6.5 mm from the shallow cartilage margin and 5.8 mm from the inferior cartilage margin. On the tibia, the center of the AM bundle is aligned with the anterior horn of the lateral meniscus, while the center of the PL bundle was located 11.2 mm (± 1.2) posterior and 4.1 mm (± 0.6) medial to the anterior insertion of the lateral meniscus. Radiographically, the center of the PL bundle is anterior along Blumensaat's line and lower in the femoral notch along the height of the condyles than the center of the AM bundle. At the tibia, the center of the AM bundle is at 30% and the PL bundle is located at 44% using the method of Stäubli and Rauschning. Conclusion The center of the femoral PL bundle is shallow and inferior to the AM bundle. On the tibia, the AM bundle lies anterior when compared with the typical single-bundle ACL tunnel that reflects the PL bundle. Clinical Relevance To imitate the anatomy of the intact ACL, it is mandatory to place the tunnels exactly within the femoral origin and tibial insertion of the ACL.

Tunnel Convergence in Combined Anterior Cruciate Ligament and Posterolateral Corner Reconstruction

To examine the geometric relationship between tunnels created in the lateral femoral condyle in reconstruction of the anterior cruciate ligament (ACL) and the posterolateral structures. The geometric relationship between a standard ACL tunnel and 11 lateral femoral tunnel variations in synthetic femur specimens was examined. Tunnel collision frequency and tunnel separation were measured radiographically. Subsequent evaluation was performed on 7 paired cadaveric specimens (14 knees) to access the efficacy of 2 configurations. Phase I-Tunnel collision frequency was 0% and 58% for 25-mm and 30-mm tunnel depths, respectively. Axial angles greater than 40 degrees and coronal angles > or =20 degrees resulted in unsafe configurations. The safest position for lateral tunnel placement was straight lateral approach (0 degrees in the coronal plane) with increased axial plane orientation (hand dropped toward the floor 40 degrees). The safe zone for lateral tunnel configuration was determined to be between [0,0] and [0,40] ([coronal, axial]). Phase II--Control group ([0,0]) collision frequencies were 43% and 86% for the 25-mm 30-mm tunnels, respectively. Experimental group ([0,40]) collision frequencies were 29% and 43% for the 25-mm and 30-mm tunnel, respectively. In femoral condyles measuring <35 mm, collision rates were 100% versus 0% in the control group ([0,0]) versus the experimental group ([0,40]). In specimens where no collision was seen, tunnel separation distance was 4.5 +/- 4.4 mm and 5.8 +/- 2.2 mm for the control and experimental groups, respectively (P = .39). Tunnel collision occurred often. Tunnel collision is dependent on femoral condyle geometry, tunnel depth, and tunnel configuration. To minimize the potential for tunnel collision, the surgeon should maintain a neutral alignment in the coronal plane, limit lateral tunnel depth to < or =25 mm, and direct the lateral tunnel anteriorly in the axial plane to a maximum of 40 degrees. This study describes guidelines for tunnel placement to prevent tunnel collision when performing combined ACL and posterolateral corner reconstruction.

Single-Staged Anterior Cruciate Ligament Revision Reconstruction Using Autologous Hamstring Tendons

Summary: With the increasing number of primary anterior cruciate ligament (ACL) reconstructions, it must be expected that ACL revision surgery will also become more frequent. The goals of revision ACL reconstruction are equal to primary ACL reconstruction, including stabilization of the knee, prevention of further injury to articular cartilage and menisci, and recovery of knee function. In primary ACL reconstruction, tunnel malplacement and unrecognized associated ligamentous pathologies often are responsible for postoperative graft failure. Thus, preoperative planning begins with detailed analysis of failure mechanisms by thorough preoperative history-taking, comprehensive physical examination, and appropriate radiographic evaluation. Treatment plan addresses issues of hardware removal, need for a staged procedure or concomitant surgery, graft source, tunnel placement, and graft fixation. Successful revision ACL surgery requires a motivated and compliant patient and an experienced surgeon who is proficient in a variety of different surgical techniques, graft sources, and graft fixation techniques. However, because clinical outcome is reported to be worse in revision compared with primary ACL reconstruction, the importance of counseling the patient preoperatively regarding less satisfactory results than in most primary ACL reconstructions must be emphasized. This article provides a summary of indications, surgical techniques, and clinical outcome in single-staged hamstring tendon ACL revision reconstruction.

The incidence and significance of femoral tunnel widening after quadrupled hamstring anterior cruciate ligament reconstruction using femoral cross pin fixation

Purpose: The purpose of this study was to evaluate the amount of femoral tunnel widening that occurred after anterior cruciate ligament reconstruction using quadrupled hamstring autografts and to determine the clinical significance of any such tunnel enlargement. Type of Study: Retrospective clinical analysis. Methods: Twenty-nine patients who had undergone reconstruction of a torn anterior cruciate ligament with quadrupled hamstring autograft and cross pin femoral fixation were evaluated to determine the incidence and significance of postoperative femoral tunnel widening. A single surgeon performed all procedures, and average follow-up was 18.4 months (range, 12 to 31.5 months). All patients underwent flexion posteroanterior and lateral radiographs, an examination for determination of an International Knee Documentation Committee (IKDC) rating, had KT-1000 data collected, and completed Lysholm and Knee Outcome Survey functional questionnaires. Femoral tunnels were clearly seen in 27 patients. The tunnel diameters were measured at the opening of the tunnel, at the widest part of the tunnel, and just proximal to the cross pin. The amount of tunnel widening for each patient was then compared with the individual’s KT-1000 data, IKDC rating, and Lysholm and knee outcome survey scores to assess correlation. Results: Four different tunnel morphologies were noted, with the linear type being the most common. The widening at the greatest tunnel diameter was 65.5% on average. Side-to-side KT-1000 differences averaged 1.04 mm at 30 lb, and 1.10 mm at manual maximum. Eleven patients had IKDC overall ratings of normal, 13 had ratings that were nearly normal, and 2 had abnormal. Average Lysholm and knee outcome survey scores were 92.6 and 93.9, respectively. A significant correlation was found only between F2 and F3 widening with Lysholm scores. However, the significance was eliminated with removal of 2 outliers. Conclusions: The exact etiology of postoperative anterior cruciate ligament tunnel widening remains unknown. The present study reveals that significant tunnel widening occurs with quadrupled hamstring autografts and femoral cross pin fixation. However, the widening does not appear to have a significant effect on postoperative ligament laxity or functional knee scores, at least in the short term.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 5 (May-June), 2003: pp 470–476

Anterior cruciate ligament tunnel placement: Comparison of insertion site anatomy with the guidelines of a computer-assisted surgical system

Purpose: With the development of computer-assisted surgery (CAS) systems, the surgeon’s ability to operate a CAS planning station will become essential. For example, default parameters in computed tomographic (CT) data are being used to place tunnels in anterior cruciate ligament (ACL) reconstruction. The goal of this study was to compare the location of the insertion sites in ACL reconstruction anatomically, via roentgenographic images and via CT scan data and to validate these tunnel placement parameters. Type of Study: Cadaveric analysis. Methods: Eight human cadaveric knees were marked with 6 copper wires 1 mm in diameter around the circumference of the insertions of the ACL. Using lateral roentgenograms and CT scans that were subsequently transferred to the CAS planning station, the tunnel locations were determined. These were based on a distance from the back of the condyle (location A) and from the roof of the notch (location B) on the femur and on a distance posterior from the tuberosity to the posterior margin along the tibial plateau, which is set as the CAS planning station’s default. Locations according to roentgenograms and CT scans were then compared and the accuracy of the CAS planning station was assessed. Results: Comparison of roentgenograms and CT revealed a femoral insertion at 27.5% ± 3.2% and 26.9% ± 3.5% (roentgenograms) and 26.6% ± 1.9% and 26.3% ± 2.4% (CT), respectively. The CAS planning station provided a tunnel location that was 1.3 ± 1.0 mm (0.3 to 2.5 mm) away from the actual femoral ACL insertion. The tibial tunnel was placed according to the copper wire markers and was found to be at 46.2% ± 2.8% (roentgenograms) and 45.4% ± 2.1% (CT). No statistical differences between position in CT and roentgenograms could be detected (P > .05). Conclusions: The compared methodologies showed similar locations of the ACL insertions, assuring accurate preoperative planning with the CAS system. However, the CAS system requires adjustment to each individual knee anatomy.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 2 (February), 2003: pp 154–160