Anterior Cruciate Ligament Femoral Tunnel Research Articles

Incidence of Convergence Between Distally and Anteriorly Oriented ALL Femoral Tunnels and ACL Femoral Tunnels in Combined ACL and ALL Reconstruction: 3-Dimensional Computed Tomography Analysis of 227 Patients

Background: Adjusting the direction of the anterolateral ligament (ALL) femoral tunnel is suggested to avoid tunnel convergence during anterior cruciate ligament (ACL) reconstruction. Yet, there has been no in vivo clinical study reporting the effect of changing the direction of the ALL tunnel on the incidence of convergence with the ACL tunnel. Purpose: To report the incidence of convergence between the ACL femoral tunnel and a distally and anteriorly directed ALL femoral tunnel and to determine a safe distal angle and anterior angle. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 227 patients undergoing concomitant ALL and anatomic single-bundle ACL reconstruction between January 2020 and December 2022 were retrospectively reviewed. The tunnel convergence rate, angular orientation of the tunnels, and distance between tunnels were obtained using postoperative computed tomography. The patients were grouped based on the direction of the ALL tunnel (transverse vs distal anterior) and the presence of tunnel convergence (convergence vs no convergence). Results: The overall tunnel convergence rate was 53.3% (121/227 patients). Tunnel convergence was observed less frequently in the distal anterior group (33.7%) than in the transverse group (65.2%) (P < .001). The no convergence group showed an ALL tunnel oriented more distally (20.2°± 11.1°) and anteriorly (19.5°± 10.2°) compared with the convergence group (8.7°± 6.5° and 6.9°± 5.3°, respectively) (P = .005 and P = .008, respectively). There were no cases of tunnel convergence for ALL tunnels >24.3° distally and >25.5° anteriorly. There was no difference in the angle of the ACL femoral tunnel between all groups. Conclusion: A distally and anteriorly directed ALL femoral tunnel reduced the incidence of convergence with the ACL femoral tunnel. A distal angle >24.3° and an anterior angle >25.5° of an ALL tunnel are suggested to safely avoid convergence with the ACL tunnel.

Lateral Extra-Articular Tenodesis Staple Risks Penetration of Anterior Cruciate Ligament Reconstruction Tunnel

To identify the risk of anterior cruciate ligament (ACL) femoral tunnel penetration with the use of a staple for lateral extra-articular tenodesis (LET) graft fixation and to determine whether this varied between 2 different techniques for ACL femoral tunnel drilling. Twenty paired, fresh-frozen, cadaver knees underwent ACL reconstruction with a LET. Left and right knees were randomized to ACL reconstruction with femoral tunnel creation by use of either a rigid guide pin and reamer through the accessory anteromedial portal or by the use of a flexible guide pin and reamer through the anteromedial portal. Immediately after tunnel creation, the LET was performed and fixated with a small Richard's staple. Fluoroscopy was used to obtain a lateral view of the knee to determine staple position, and visualization of the ACL femoral tunnel was performed with the arthroscope to investigate penetration of the staple into the femoral tunnel. The Fisher exact test was conducted to determine whether there was any difference in tunnel penetration between tunnel creation techniques. The staple was noted to penetrate the ACL femoral tunnel in 8 of 20 (40%) extremities. When stratified by tunnel creation technique, the Richards staple violated 5 of 10 (50%) of the tunnels made via the rigid reaming technique compared with 3 of 10 (30%) of those created with a flexible guide pin and reamer (P= .65). A high incidence of femoral tunnel violation is seen with lateral extra-articular tenodesis staple fixation. Level IV, controlled laboratory study. The risk of penetrating the ACL femoral tunnel with a staple for LET graft fixation is not well understood. Yet, the integrity of the femoral tunnel is important for the success of ACL reconstruction. Surgeons can use the information in this study to consider adjustments to operative technique, sequence, or fixation devices used when performing ACL reconstruction with concomitant LET to avoid the potential for disruption of ACL graft fixation.

ACL stump and ACL femoral landmarks are equally reliable in ACL reconstruction for assisting ACL femoral tunnel positioning.

This study aimed to comparatively evaluate the accuracy of femoral tunnel positioning after anatomic single-bundle anterior cruciate ligament (ACL) reconstruction performed with the remnant preservation (RP) technique versus the non-remnant preservation (NRP) technique. A retrospective review of 145 patients who underwent ACL reconstruction from May 2020 to May 2022 were performed in this single-surgeon study. A total of 120 patients met the inclusion criteria and were allocated into two groups according to the surgical technique (i.e. RP group and NRP group). The relative location of the femoral tunnel in the lateral condyle was evaluated as a percentage using a standardized grid system on the three-dimensional computed tomography (3D-CT) image. The accuracy and precision of the RP group were assessed based on published anatomical data in direct comparison with the NRP group. According to the surgical procedure, 57 of the 120 patients included were allocated into the RP group, and 63 into the NRP group. Significant differences were observed between the two groups in terms of tunnel position (posterior-to-distal (PD): 28.4 ± 5.4% (RP) vs. 31.8 ± 5.3% (NRP); P = 0.01), (anterior-to-posterior (AP): 32.6 ± 7.7% (RP) vs. 38.8 ± 7.7% (NRP); P = 0.00), while no significant differences were found in terms of the accuracy (8.6% (RP) vs. 8.9% (NRP); n.s) and precision (4.4% (RP) vs. 5.6% (NRP); n.s) of femoral tunnel positioning between the two groups. From this single-surgeon study, it was concluded that there were no differences in the creation of ACL femoral tunnel between the RP technique and the non-remnant preserving technique. Meanwhile, the RP technique would not sacrifice the ideal position of the femoral tunnel and is able to retain the possible benefits of the ACL stump. Level III.

The orientation of the ALL femoral tunnel to minimize collision with the ACL tunnel depends on the need or not of far-cortex drilling.

To (1) evaluate the optimal drill orientation of the anterolateral ligament (ALL) femoral tunnel to minimize collision with the anterior cruciate ligament (ACL) femoral tunnel during anatomical ACL reconstruction according to the need for far-cortex drilling and (2) investigate the geometric factors that affect tunnel collision secondary to drill orientation of the ALL femoral tunnel. A three-dimensional femoral model of patients who underwent anatomical single-bundle ACL reconstruction between 2015 and 2016 was constructed, and the geometric factors were evaluated. Virtual ALL femoral tunnels were created to simulate 45 drilling conditions. For each condition, whether the virtual ALL femoral tunnel and its trajectory violated the femoral cortex and the minimum distance between tunnels was investigated. Thirty-nine subjects were included. Overall violation rates of the femoral cortex by the ALL tunnels and its trajectories were 11.1% (195 of 1755 conditions) and 40.7% (714 of 1755 conditions), respectively. A drilling angle of axial 0° and coronal -40° showed the longest minimum distance between tunnels without femoral cortex violation by the ALL tunnel (6.3 ± 4.0mm; collision rate 2.6% [1 of 39 subjects]). With simultaneous consideration of the ALL tunnel's trajectory representing far-cortex drilling, a drill angle of axial 40° and coronal 10° showed the longest minimum distance between tunnels without femoral cortex violation (0.6 ± 3.9mm; collision rate 38.5% [15 of 39 subjects]). For surgical techniques requiring far-cortex drilling, regression analyses were performed on geometric factors that could affect tunnel collision, which revealed that the sagittal inclination angle of the ACL and the distance between the ACL femoral tunnel's outlet and ALL's femoral attachment were associated with tunnel collision. The optimal drill orientations of the ALL femoral tunnel to minimize collision with the ACL femoral tunnel were axial 0° and coronal -40° for surgical techniques not requiring far-cortex drilling and axial 40° and coronal 10° for techniques requiring far-cortex drilling. For techniques requiring far-cortex drilling, additional adjustment for orientation of the ACL femoral tunnel is required to reduce the risk of tunnel collision. Therefore, an individualized surgical strategy should be applied according to the graft fixation method of the ALL femoral tunnel.

State of the mineralized tissue comprising the femoral ACL enthesis in young women with an ACL failure.

Despite poor graft integration among some patients that undergo an anterior cruciate ligament (ACL) reconstruction, there has been little consideration of the bone quality into which the ACL femoral tunnel is drilled and the graft is placed. Bone mineral density of the knee decreases following ACL injury. However, trabecular and cortical architecture differences between injured and non-injured femoral ACL entheses have not been reported. We hypothesize that injured femoral ACL entheses will show significantly less cortical and trabecular mass compared with non-injured controls. Femoral ACL enthesis explants from 54 female patients (13-25 years) were collected during ACL reconstructive surgery. Control explants (n = 12) were collected from seven donors (18-36 years). Injured (I) femoral explants differed from those of non-injured (NI) controls with significantly less (p ≤ 0.001) cortical volumetric bone mineral density (vBMD) (NI: 736.1-867.6 mg/cm3 ; I: 451.2-891.9 mg/cm3 ), relative bone volume (BV/TV) (NI: 0.674-0.867; I: 0.401-0.792) and porosity (Ct.Po) (NI: 0.133-0.326; I: 0.209-0.600). Injured explants showed significantly less trabecular vBMD (p = 0.013) but not trabecular BV/TV (p = 0.314), thickness (p = 0.412), or separation (p = 0.828). We found significantly less cortical bone within injured femoral entheses compared to NI controls. Lower cortical and trabecular bone mass within patient femoral ACL entheses may help explain poor ACL graft osseointegration outcomes in the young and may be a contributor to the osteolytic phenomenon that often occurs within the graft tunnel following ACL reconstruction.

Novice Surgeon Portal Preference to Visualize the Femoral Anterior Cruciate Ligament Footprint: The Accessory Medial Portal Offers Improved Visualization

PurposeTo evaluate participant opinions on the appropriateness of different viewing angles by asking 8 questions, using visual content techniques.MethodsSurvey information from participants was used in this study. We used images of a patient who was operated on for symptomatic knee instability. Participants were asked whether the visual angle could determine the femoral tunnel entry point or evaluate anterior cruciate ligament (ACL) integrity.ResultsQuestionnaires were completed by 40 participants. When all responses were evaluated, participant opinions on the accessory medial portal (AMP) were more positive than opinions on images taken from the anterolateral portal (ALP). These observations were statistically significant (P < .005). Both ACL integrity assessments and femoral tunnel entry site questions were evaluated, we observed that participant opinions on the AMP for both types of evaluation were more positive than opinions on the ALP. This observation was statistically significant (P < .005). When evaluations with photos and video transcripts were compared, no significant differences in terms of participant opinions were observed (P < .005).ConclusionsAMP use may be a valuable tool for assistant and postgraduate education, as it offers a more suitable view angle for ACL reconstruction.Level of evidenceLevel V, survey study.

Repair of the Posterior Lateral Meniscal Root Tear: Suture Anchor Fixation Through the Outside-In Anterior Cruciate Ligament Reconstruction Femoral Tunnel

Posterior lateral meniscus root tears are defined as tears that occur within 9 mm of the posterior lateral meniscus insertion or as avulsions of the insertion. If root tears are left unrepaired, functional alterations and early degenerative changes occur in the affected compartment. Several surgical techniques have been described to reattach the posterior horn of the lateral meniscus, including transtibial pull-out technique and side-to-side repair technique. This surgical technique reports an alternative way to repair posterior lateral meniscus root tears that are associated with or without an anterior cruciate ligament graft tear. The technique involves the placement of a suture anchor on the lateral meniscus root footprint through the outside-in anterior cruciate ligament femoral tunnel, which minimizes the possibility of iatrogenic lesions and facilitates repair.

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.

Anterior Cruciate Ligament Femoral Tunnel Placement: An Analysis of the Intended Versus Achieved Position for 221 International High-Volume ACL Surgeons

Background: Femoral tunnels that are not anatomically placed within the native anterior cruciate ligament (ACL) footprint during ACL reconstruction are associated with residual instability, graft rupture, and poor clinical outcomes. Although surgeons may intend to place their femoral tunnels within the native ACL attachment, this is not always achieved. This study assesses the variation between intended and achieved femoral tunnel positions in a large cohort of experienced ACL surgeons. Hypothesis: The accuracy with which experienced ACL surgeons achieve their intended femoral tunnel position is dependent on viewing portal, localization strategy, and drilling technique. Study Design: Controlled laboratory study. Methods: A total of 221 surgeons indicated their intended femoral tunnel location on a true lateral radiograph of a cadaveric knee specimen and a scaled photograph. Each surgeon then arthroscopically demonstrated the femoral tunnel on the specimen. The position was captured using fluoroscopy. The Euclidean distance (the straight-line distance between 2 points) between the intended and achieved tunnel positions, referenced to a grid applied to the lateral femoral condyle, was compared. Data were analyzed according to surgeons’ viewing portal (anteromedial [AM] or anterolateral [AL]), tunnel localization strategy (offset aimer, estimation from landmarks, ACL ruler, or C-arm fluoroscopy), and stated drilling technique (transtibial, AM portal, or outside-in). Results: Surgeons who viewed the lateral intercondylar notch wall through the AM portal were closer (mean distance, 9.5) to their intended position than those who viewed through the AL portal (mean distance, 15.1; P < .0001). By localization strategy, the mean distance between achieved and intended tunnel positions was greater for surgeons who used an offset aimer (14.5) and estimated the femoral tunnel position (12.9) than for those using a malleable ACL ruler (8.1; P < .0001) and fluoroscopy (4.3; P < .0001). Surgeons’ preferred drilling technique (AM portal, transtibial, or outside-in) had no effect on distance between intended and achieved positions. However, the mean achieved position was higher in the intercondylar notch for those using transtibial drilling (P < .042). Conclusion: Surgeons using the AM portal to view the femoral attachment site were closer to their intended tunnel position than those who viewed it with the arthroscope in the AL portal. Surgeons who used fluoroscopy to localize femoral tunnel position were the closest to their intended position. Those who used estimation or an offset aimer had the farthest distance between achieved and intended tunnel positions. Clinical Relevance: Although accurate tunnel placement can be achieved using any method, given the disparity between intended and achieved tunnel positions, it may be advisable, even for high-volume surgeons, to verify the placement of their tunnels using either fluoroscopy or a malleable ACL ruler to ensure that they achieve their intended position. Fluoroscopy may be particularly useful for cases where the native femoral stump is no longer visible and for revisions. Viewing through the AM portal is recommended to aid accuracy of tunnel placement.

Evaluating for Tunnel Convergence in Anterior Cruciate Ligament Reconstruction With Modified Lemaire Tenodesis: What Is the Best Tunnel Angle to Decrease Risk?

The purpose of this study was to analyze postoperative computed tomography (CT) scan evaluations of patients who had undergone a combined anterior cruciate ligament (ACL) reconstruction and modified Lemaire anterolateral tenodesis (ALT) with femoral fixation through a bony tunnel. Postoperative CT scans of 52 patients who had undergone combined ACL and ALT were prospectively evaluated. ACL femoral tunnels were drilled through an anteromedial portal in the center of the native footprint. An ALT fixation tunnel was drilled 5mm proximal to the lateral epicondyle, aiming at an inclination of 30° proximally and 30° anteriorly. Two independent observers evaluated the CT scans measuring any degree of collision, the shortest distance between the tunnels, and the inclination of the ALT tunnels. Measurements were carried out at both the cortical level and on a plane passing 1cm deeper in the lateral condyle. At the level of the cortex, no convergence of the tunnels was identified. In 14 of 52 cases (26.9%), the shortest distance between the tunnels was less than 5mm. Tunnel collision occurred in 8 of 52 cases (15.4%), and the bone bridge between the tunnels was less than 5mm in 11 cases (21.1%) when the measurements were made on the deeper plane. When the inclination on the axial plane was less than 15°, a collision always (P < .001) occurs. When it was more than 20°, no collision occurred (P < .001). No correlation between convergence and the inclination of the ALT tunnel on the coronal plane was detected. To fix a modified Lemaire ALT through a femoral tunnel avoiding any interference with an anatomic femoral ACL tunnel, we recommend that the femoral tunnel be drilled with an inclination of at least 20° anteriorly. IV, therapeutic case series.

Do Rotation and Measurement Methods Affect Reliability of Anterior Cruciate Ligament Tunnel Position on 3D Reconstructed Computed Tomography?

Background:The literature has seldom investigated the anterior cruciate ligament (ACL) tunnel position while considering the effect of rotation of 3-dimensional computed tomography (3D-CT) images during measurements.Hypothesis:We hypothesized that (1) measurement of the ACL tunnel position in the femur and tibia through use of 3D-CT is considerably influenced by rotation of the 3D model and (2) there exists a reliable measurement method for ACL tunnel position least affected by rotation.Study Design:Controlled laboratory study.Methods:The 3D-CT images of 30 randomly selected patients who underwent single-bundle ACL reconstruction were retrospectively reviewed. For femoral tunnel assessments, rectangular reference frames were used that involved the highest point of the intercondylar notch and outer margins of the lateral femoral condyle (method 1), the highest point of the intercondylar notch and outer margins of the lateral wall of the intercondylar notch (method 2), and the lowest point of the intercondylar notch and outer margins of the lateral femoral condyle (method 3). For tibial tunnel assessments, rectangular reference frames with the cortical outline at the articular surface of the tibia (method A) and the cortical outline of the proximal tibia (method B) were used. For both femoral and tibial assessments, the tunnel positions at 5°, 10°, and 15° of rotation of the 3D model were compared with that at a neutral position.Results:The values measured by methods 1 and 3 showed significant differences at greater than 5° of rotation compared with the value at the neutral position, whereas method 2 showed relatively consistent results. However, the values measured with both methods A and B showed significant differences at greater than 5° of rotation compared with the value at the neutral position.Conclusion:The tunnel position on 3D-CT images was significantly influenced by rotation during measurements. For femoral tunnel position, measurement with a reference frame using the lateral wall of the intercondylar notch (method 2) was the least affected by rotation, with relatively consistent results.Clinical Relevance:This study demonstrates that measurement using the lateral wall of the intercondylar notch might be a consistent and reliable method for evaluating the ACL femoral tunnel position considering the effect of 3D-CT image rotation during measurements. However, both methods to measure tibial tunnel position described in this study were similarly affected by rotation.

High Risk of Tunnel Convergence in Combined Anterior Cruciate Ligament Reconstruction and Lateral Extra-articular Tenodesis

Background: Lateral extra-articular tenodesis (LET) is being increasingly added to primary and revision anterior cruciate ligament (ACL) reconstruction to address residual anterolateral rotatory instability. However, currently there is a lack of knowledge on how close the femoral tunnels are when combining these procedures. Purpose/Hypotheses: To assess the risk of tunnel convergence in combined ACL and LET procedures using 2 different surgical techniques (Lemaire and MacIntosh). It was hypothesized that the risk of tunnel convergence would be greater when using the more distally located Lemaire position. The authors further hypothesized that tunnel proximity would be influenced by knee size. Study Design: Controlled laboratory study. Methods: Ten fresh-frozen cadaveric knees were used for this study. In each specimen, an anatomic ACL femoral tunnel and 2 LET tunnels were drilled using the Lemaire and MacIntosh positions, respectively. After knee dissection, minimal distances between each ACL and LET tunnel were directly measured on the lateral femoral cortex. Furthermore, computed tomography scans were obtained to measure intertunnel convergence and lateral femoral condyle (LFC) width. On the basis of the average LFC width, knees were divided into large and small knees to determine a relationship between knee size and tunnel convergence. Results: Convergence of ACL and LET tunnels occurred in 7 of 10 cases (70%) using the Lemaire attachment position. All tunnel collisions occurred directly on the lateral femoral cortex, while intertunnel (intramedullary) conflicts were not observed. Collisions emerged in both small (n = 4) and large (n = 3) knees. Critical tunnel convergence did not occur using the MacIntosh position. The mean minimal distance between the LET and ACL tunnel using the Lemaire and MacIntosh positions was 3.1 ± 4.6 mm and 9.8 ± 5.4 mm, respectively. Conclusion: Tunnel convergence was more frequently observed in combined ACL and LET reconstruction using the Lemaire technique, independent of the knee size. LET femoral tunnel positioning according to the MacIntosh reconstruction was not associated with tunnel collision. Clinical Relevance: These findings help to raise the awareness for the risk of tunnel convergence in combined ACL and LET procedures. Surgeons may contemplate adjustments on the ACL femoral tunnel drilling technique or fixation device when applying an additional Lemaire procedure. However, in the absence of clinical outcome studies comparing different LET techniques, it remains unclear which technique is superior in a clinical setting.

Safe drilling angles avoid femoral tunnel complications during combined anterolateral ligament and anterior cruciate ligament reconstruction.

To determine the best angle to drill the femoral tunnels of an anterolateral ligament (ALL) anatomic reconstruction combined with a single-bundle anterior cruciate ligament (ACL) reconstruction to avoid tunnel collisions and cortical disruption. Ten cadaveric knees were studied. Single-bundle anatomic ACL femoral tunnels were arthroscopically drilled. The starting point of the ALL femoral tunnel was located posterior and superior to the lateral epicondyle. ALL tunnels were drilled at four different angulations: (1) 0° axial/0° coronal, (2) 0° axial/30° coronal superior, (3) 30° axial anterior/0° coronal, and (4) 30° axial anterior 30° coronal superior. Specimens were scanned by computed tomography to measure the relations of each trajectory with the ACL socket and the nearest cortical bone. None of the four trajectories studied presented risk of collision with the ACL. The tunnel at 30° anterior/30° proximal presented the safest distance to the ACL socket (P = 0.01) [mean distance 18.6mm (SD ± 6.7)]. However, both tunnels angled at 0° in the axial plane presented a high risk of posterior femoral cortex disruption (P = 0.01), either by close proximity or direct contact in some specimens (mean distance 3.1mm (SD ± 2.8) at 0° axial/0° coronal and 3.7mm (SD ± 2.2) at 0° axial/30° coronal). When performing simultaneous ACL and ALL ligament reconstruction, the ALL femoral tunnel should be drilled with an angle of 30° anterior in the axial plane and 30° proximal in the coronal plane. Tunnels with an angle of 0° in the axial plane showed high risk of contact and disruption of the posterior femoral cortex; thus, these angles should be avoided. The clinical relevance of this work is that an ALL anatomical reconstruction does not represent a risk when performing a simultaneous ACL reconstruction as long as the ALL tunnel is reamed with a proximal and anterior angulation.

High risk of tunnel convergence during combined anterior cruciate ligament and anterolateral ligament reconstruction.

To assess the risk of femoral tunnel convergence in combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstructions. The hypothesis was that a more proximal and anterior orientation of the ALL femoral tunnel should reduce the risk of convergence with the ACL femoral tunnel. 15 fresh-frozen cadaver knees were examined. An anatomic ACL femoral tunnel was drilled arthroscopically in each specimen and ALL tunnels were made in two directions: (1) 0° coronal angulation and 20° axial angulation, (2) 30° coronal angulation and 30° axial angulation. Computed tomography scans were performed to investigate tunnel convergence and to measure the minimal distance between tunnels, tunnel length and the LFC width. Tunnel convergence occurred in 20 of 30 cases (67%). Convergence was significantly reduced when tunnels were drilled at 30° coronal and 30° axial angulation (p < 0.05). The mean length of the ALL tunnel was 15.9mm [95% CI (13.6; 18.1)] and was independent of ALL tunnel angulation. The mean minimal distance between the ALL and ACL tunnel was 3.1mm [95% CI (2.1; 4.1)]. The odds ratio for tunnel convergence was 3.5 for small LFC, relative to large LFC (n.s.) CONCLUSION: A high risk of tunnel convergence was observed when performing combined ACL and ALL reconstructions. The clinical relevance of this work is that the occurrence of tunnel conflicts can be reduced by aiming the ALL tunnel in a more proximal and anterior direction. Surgeons should be aware of this, since tunnel convergence could jeopardize the ACL reconstruction and fixation.

All-Epiphyseal Anterior Cruciate Ligament Femoral Tunnel Drilling: Avoiding Injury to the Physis, Lateral Collateral Ligament, Anterolateral Ligament, and Popliteus—A 3-Dimensional Computed Tomography Study

To investigate the relation of the at-risk structures (distal femoral physis, lateral collateral ligament, anterolateral ligament, popliteus, and articular cartilage) during all-epiphyseal femoral tunnel drilling. A second purpose was 2-fold: (1) to develop recommendations for tunnel placement and orientation that anatomically reconstruct the anterior cruciate ligament (ACL) while minimizing the risk of injury to these at-risk structures, and (2) to allow for maximal tunnel length to increase the amount of graft in the socket to facilitate healing. Three-dimensional models of 6 skeletally immature knees (aged 7-11years) were reconstructed from computed tomography and used to simulate all-epiphyseal femoral tunnels. Tunnels began within the ACL footprint and were directed laterally or anterolaterally, with the goal of avoiding injury to at-risk structures. The spatial relation between the ideal tunnel and these structures was evaluated. Full-length tunnels and partial length condyle sockets were simulated in the models using the same trajectories. An anterolateral tunnel could be placed to avoid direct injury to lateral structures. The safe zone on the anterolateral aspect of the femur was larger than that of a tunnel with a direct lateral trajectory (median 127mm2 vs 83mm2, P= .028). Anterolateral tunnels were longer than direct lateral tunnels (median 30mm vs 24mm, P= .041). Safe angles for anterolateral tunnels were 34° to 40° from the posterior condylar axis; direct lateral tunnels were drilled 4° to 9° from the posterior condylar axis. Sockets could be placed without direct injury to structures at risk with either orientation. An all-epiphyseal ACL femoral tunnel can be placed without causing direct injury to at-risk structures. Atunnel angled anterolaterally from the ACL origin is longer and has a larger safe zone compared with the direct lateraltunnel. The largest safe zone for femoral all-epiphyseal ACL drilling was (1) anterior to the lateral collateral ligament origin, (2) distal to the femoral physis, and (3) proximal to the popliteus tendon origin. A direct lateral tunnel may also be used, but has a smaller safe zone. Sockets or partial length tunnels may have a lower risk of injury to at-risk structures.

A study on associated injuries of anterior cruciate ligament tear

Introduction: Over the last decade, reconstruction of the anterior cruciate ligament (ACL) has evolved from a surgical technique in which the objectives were ‘isometric’ femoral tunnel placement and avoidance of inter-condylar notch roof impingement, towards an ‘anatomic’ surgical technique which attempts to restore the native ACL. Achieving the goals of isometric ACL graft placement and avoidance of roof impingement often resulted in the ACL femoral tunnel extending into the roof of the notch, outside of the native ACL femoral attachment site and the tibial tunnel being positioned in the posterior half of the native ACL tibial attachment site. Methodology: All patients admitted with clinico-radiological diagnosis of ACL tear with h/o injury (trauma) who met the inclusion criteria. This was a Prospective observational study with the minimum follow up 12 months. The sample size was 30. Results: A Total of 90% (27 cases) (n=27) patients had associated injuries usually the meniscal tear. Isolated medial meniscal tear were found in 33.3% (10 cases) (n=10) while isolated lateral meniscus tear were found in 33.3% (10 patients) (n=10) of cases. Combined medial and lateral meniscus tear were found in 23%% (7 cases) (n=7). Conclusion: Chondral changes were found in 30% (9 cases) (n=9) MCL, LCL and posterior cruciate ligament tear was found in none.

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.

Biomechanical Comparison of Fixed-Loop and Adjustable-Loop Cortical Suspensory Devices for Metaphyseal Femoral-Sided Soft Tissue Graft Fixation in Anatomic Anterior Cruciate Ligament Reconstruction Using a Porcine Model

To compare the displacement, stiffness, and ultimate failure load of a fixed-loop cortical suspensory device with 2 adjustable-loop devices when positioned on metaphyseal bone. Thirty devices (10 of each device) were positioned on the metaphyseal cortex of 30 porcine femora simulating anatomic anterior cruciate ligament femoral tunnel placement. Bovine tendons were used for soft tissue grafts, and the constructs were then cycled 1,000 times and pulled to failure, measuring displacement, stiffness, and failure load. Initial displacement, cyclic displacement, and total displacement were 2.98mm, 2.09mm, and 5.08mm for the Endobutton CL (ECL), 2.82mm, 2.27mm, and 5.09mm for the Tightrope (TRT), and 4.25mm, 3.19mm, and 7.44mm for the adjustable-loop ToggleLoc Inline with Ziploop (TLZ), respectively. There was no difference between the ECL and the TRT on any measured outcome. Differences between theTLZ and ECL were statistically significant (initial displacement P= .024, cyclic displacement P < .001, and total displacement P < .001), as were those between the TLZ and TRT (initial displacement P= .010, cyclic displacement P=.001, and total displacement P < .001). Failure loads were 804N, 801N, and 682N for the TRT, ECL, and TLZ, respectively, with no statistically significant difference. When positioned on the metaphyseal cortex, there was no difference in the biomechanical performance of the fixed-loop ECL and adjustable-loop TRT, and no lengthening of the TRTs was observed during cycling. However, the TLZ showed statistically significantly lower stiffness and more displacement during cycling with lengthening of the adjustable loop, the clinical significance of which is unknown. When used for femoral-sided soft tissue graft fixation in an anatomically placed femoral tunnel, the adjustable-loop TRT was biomechanically equivalent to the fixed-loop ECL. However, the adjustable-loop TLZ showed displacement during biomechanical testing that could potentially contribute to clinical failure after anterior cruciate ligament reconstruction. However, the clinical significance was not directly tested.

Multiple Ligament Reconstruction Femoral Tunnels: Intertunnel Relationships and Guidelines to Avoid Convergence

Background: Knee dislocations often require multiple concurrent ligament reconstructions, which involve creating several tunnels in the distal femur. Therefore, the risk of tunnel convergence is increased because of the limited bone volume within the distal aspect of the femur. Purpose: To assess the risk of tunnel convergence and determine the optimal reconstruction tunnel orientations for multiple ligament reconstructions in the femur. Study Design: Descriptive laboratory study. Methods: Three-dimensional knee models were developed from computed tomography scans of 21 patients. Medical image processing software was used to create tunnels for each of the primary ligamentous structures, replicating a surgical approach that would be used in multiple ligament reconstructions. Thereafter, the tunnel orientation was varied in surgically relevant directions to determine orientations that minimized the risk of tunnel convergence. The orientation of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) tunnels was held constant throughout the study, while the orientation of the fibular collateral ligament (FCL), popliteus tendon (PLT), superficial medial collateral ligament (sMCL), and posterior oblique ligament (POL) tunnels was varied to avoid convergence. Results: A high risk of tunnel convergence was observed between the FCL and ACL tunnels when the FCL tunnel was aimed at 0° in the axial and coronal planes. Aiming the FCL tunnel 35° anteriorly minimized convergence with the ACL tunnel. No tunnel convergence was observed for the PLT tunnel aimed 35° anteriorly and parallel to the FCL tunnel. To avoid convergence between the sMCL and PCL tunnels, the sMCL tunnels should be aimed 40° proximally in the coronal plane and 20° to 40° anteriorly. During concomitant POL reconstruction, the sMCL should be aimed 40° proximally and anteriorly and the POL 20° proximally and anteriorly. The PLT and POL tunnels aimed at 0° in both the coronal and axial planes had an increased risk of violating the intercondylar notch. Conclusion: Femoral tunnel orientations during multiple ligament reconstructions need to be adjusted to avoid tunnel convergence. On the lateral side, aiming the FCL and PLT tunnels 35° anteriorly eliminated convergence with the ACL tunnel. On the medial side, tunnel convergence was avoided by orienting the sMCL tunnel 40° proximally and anteriorly and the POL tunnel 20° proximally and anteriorly. The POL and PLT tunnels aimed at 0° in the axial plane had an increased risk of violating the intercondylar notch. Clinical Relevance: The risk of tunnel convergence with the ACL and PCL femoral tunnels can be reduced by adjusting the orientation of the FCL and PLT tunnels and the sMCL and POL tunnels, respectively.

Utilization of Osseous Landmarks for Anatomic Anterior Cruciate Ligament Femoral Tunnel Placement.

Accurate placement of the femoral tunnel is critical for long-term clinical success following anterior cruciate ligament (ACL) reconstruction. The purpose of the present study is to evaluate the accuracy of femoral tunnel placement when referencing osseous landmarks during ACL reconstruction. We hypothesize that referencing osseous landmarks during ACL reconstruction consistently results in anatomic placement of the ACL femoral tunnel. This study was a retrospective case series. We reviewed 83 consecutive ACL reconstructions performed by a single surgeon. The lateral intercondylar ridge and lateral bifurcate ridge were referenced intraoperatively for anatomic placement of the ACL femoral tunnel during single-bundle reconstruction. Using these landmarks, the femoral tunnel was placed in the center of the anteromedial bundle footprint on the lateral wall of the intercondylar notch. We reviewed all operative notes and intraoperative arthroscopic images to assess tunnel placement. Postoperative anteroposterior and lateral radiographs were obtained in all patients. Anatomic placement was confirmed by review of lateral radiographs utilizing both the quadrant method (QM) and Blumensaat-ridge ratio (BRR). We used a total of 80 patients for our study. Review of arthroscopic images confirmed anatomic placement of the ACL femoral tunnel in all patients. All patients demonstrated that the femoral tunnel was placed anatomically according to the BRR method. Using the QM, all femoral tunnels were placed anatomically except for one tunnel that was placed slightly anteriorly. There was excellent agreement between the two radiographic measurement techniques. The principal finding of this study indicates that the lateral intercondylar ridge and the lateral bifurcate ridge are reliable landmarks for anatomic placement of the ACL femoral tunnel. Referencing osseous landmarks during surgery can help surgeons avoid nonanatomic placement of the ACL femoral tunnel, especially in cases where the soft-tissue footprint is no longer present. Furthermore, both the radiographic QM and the BRR are valid techniques to assess for anatomic ACL femoral tunnel placement both intraoperatively and postoperatively.