Tunnel Collision Research Articles

Collision causal discovery and real-time prediction of freeway tunnels: A novel dual-task approach

Although tunnels are critical traffic nodes in freeway networks, academic research addressing their real-time traffic safety is noticeably lacking. This study proposes a novel dual-task approach to analyze causal precursors and predict real-time collision risks in freeway tunnels. Unlike traditional models, which often trade off between predictive accuracy and causal depth, the proposed approach achieves both high causal interpretability and predictive performance. The approach utilizes a structural agnostic model (SAM) to discover causal precursors of freeway tunnel collisions using observational data. The collision causal graph data is then constructed based on the causal relationships identified by SAM. Additionally, the Causal Directed Graph Convolutional Networks (CDGCN) model is developed to capture causal relationships in the graph for real-time collision prediction. Utilizing freeway tunnel collision analysis data collected from the Caltrans Performance Measurement System, the approach performs dual tasks: identifying causal precursors of collisions and predicting future collisions in real time. The SAM results reveal five critical causal precursors influencing the likelihood of collisions. Comparative analyses with existing interpretable machine learning models show similarities between the causal precursors of tunnel collision risk revealed by SAM and the important correlation precursors identified by the comparative models. However, correlation is not the same as causation. When tested against current state-of-the-art real-time collision predictive models, the proposed CDGCN model demonstrates superior accuracy, especially on datasets containing causally relevant precursors, highlighting the potential of this approach for feature selection and risk prediction. This advancement not only provides a practical framework for mitigating collision risks in freeway tunnels but also makes a significant contribution to traffic safety research.

Anterior Cruciate Ligament Over-The-Top Plus Lateral Plasty and Minimally Invasive Double-Bundle Posteromedial Corner Reconstruction

The medial collateral ligament (MCL) and the posteromedial corner (PMC) of the knee are essential structures for maintaining medial knee stability. Chronic MCL instability is infrequent but can necessitate surgical intervention. Various surgical techniques have been described, but they often involve the use of tibial tunnels, which may complicate concurrent ligament reconstructions. This study aims to present a minimally invasive double-bundle PMC reconstruction technique that avoids the use of tibial tunnels. Knee evaluation was performed using standard clinical tests and 1.5-Tesla magnetic resonance imaging. Patients with grade III Hughston MCL injuries were considered for surgery. The technique employs either an autologous semitendinosus graft or a fresh-frozen allograft, usually tibialis anterior, to reconstruct both the superficial MCL and the posterior oblique ligament. The technique described avoids the use of tibial tunnels, preserving tibial bone stock for any future procedures. The graft is secured at the femoral and tibial insertions using bioabsorbable interference screws and titanium staples, respectively. Our minimally invasive double-bundle PMC reconstruction technique offers a feasible and effective solution for patients with chronic medial knee instability. It is particularly beneficial for patients requiring multiple ligament reconstructions, as it avoids tunnel collision and preserves tibial bone stock.

An Antegrade Soft Anchor in a Retrograde Drilling for Medial Meniscus Root Repair with High Tibial Osteotomy: A Modified Approach to Avoid Tunnel Collision

An Antegrade Soft Anchor in a Retrograde Drilling for Medial Meniscus Root Repair with High Tibial Osteotomy: A Modified Approach to Avoid Tunnel Collision

Poster 351: Relation Between Femoral Anterior Cruciate Ligament Tunnel Orientation and Anterolateral Ligament Tunnel Collision in a 3D-CT Model

Poster 351: Relation Between Femoral Anterior Cruciate Ligament Tunnel Orientation and Anterolateral Ligament Tunnel Collision in a 3D-CT Model

Lateral augmentation procedures in anatomic anterior cruciate ligament reconstruction. How to avoid tunnel collision with intraoperative tunnel visualization: A technical note

Lateral extra-articular tenodesis (LET) or anterolateral ligament (ALL) reconstruction can be used as an augmentation procedure in anatomic anterior cruciate ligament (ACL) reconstruction and are thought to minimize rotational instability, lower re-rupture rates of the ACL graft and improve functional outcomes after surgery. Young patients with high-grade pivot shift or generalized laxity participating in high demand/pivoting sports are considered as the ideal candidates for such a procedure. Both in LET and in ALL reconstruction, femoral fixation of the graft using an interference screw remains a challenge due to the possibility of tunnel convergence of the two tunnels created in the femur, namely the ACL femoral tunnel and the tunnel created in the lateral femur for the LET or ALL procedure. With this technical note, we aim to describe a safe approach for femoral tunnel creation by providing the surgeon not only with instructions for a safe orientation but also with the possibility to check for a possible tunnel collision by using the arthroscope through the anteromedial portal. Although instructions can be used both for LET and ALL reconstruction (same femoral tunnel), a modified Lemaire LET is extensively described since this procedure is the authors’ preference for augmenting anatomic ACL reconstruction.

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.

Optimal Combination of Femoral Tunnel Orientation in Anterior Cruciate Ligament Reconstruction Using an Inside-out Femoral Technique Combined With an Anterolateral Extra-articular Reconstruction

Background: The optimal orientation of the anterolateral extra-articular reconstruction (ALLR) femoral tunnel to avoid collision with the anterior cruciate ligament reconstruction (ACLR) femoral tunnel is not clearly defined in the literature. Purpose: To define the optimal combination of orientations of the ALLR femoral tunnel and the ACLR femoral tunnel using an inside-out technique to minimize risk of collision between these tunnels. Study Design: Descriptive laboratory study. Methods: Three-dimensional reconstruction of magnetic resonance imaging scans of 40 knees after an isolated ACLR with an inside-out femoral technique was used to assess the collision risk between ACLR and virtual ALLR tunnels. The optimal ACLR tunnel orientation was defined as having the safest distance from the ALLR tunnel. A second collision analysis was performed on all patients presenting with an optimal orientation of the ACLR tunnel to then define the optimal ALLR tunnel orientation. The potential for trochlear damage was also studied. A collision risk of 0% to 5% was considered acceptable and referred to as “low risk.” Results: The only ALLR tunnel orientation presenting a low risk of collision with the ACLR tunnel was with an axial angle of 40° anteriorly and a coronal angle of 0°. This orientation presented a 48% risk of trochlear damage with the guide wire of the ALLR tunnel. The more posterior the orientation of the ACLR, the larger the distance from the ALLR tunnel. Among the 22 patients presenting with an optimal ACLR tunnel (alpha angle superior to 40°), the ALLR tunnels aimed with 1 of these 3 orientations presented a low risk of tunnel collision and trochlear damage: 40° axial and 10° coronal, 35° axial and 5° coronal, or 30° axial and 0° coronal. Conclusion/Clinical Relevance: To minimize risk of tunnel collision or trochlear damage when combining an inside-out ACLR with an ALLR, the ACLR tunnel should be performed with a posterior orientation (alpha angle >40°), and the ALLR tunnel should be aimed with 1 of 3 orientations: 40° axial and 10° coronal, 35° axial and 5° coronal, or 30° axial and 0° coronal.

Risk of femoral tunnel collision in combined and independent anterolateral and anterior cruciate ligament reconstruction with outside-in femoral drilling

Objectives:In combined ACL and anterolateral ligament (ALL) reconstruction with outside-in femoral drilling, there is a risk of femoral tunnel collision. The objective was to determine the optimal combination of ACL and ALL femoral tunnel orientation to minimize the risk of collision.Methods:Forty patients with isolated ACLR with inside-out femoral drilling were included. For each patient, a postoperative MRI of the femur was reconstructed in 3D. An ALL tunnel was modeled virtually with a pair of coronal and axial angles varying from 0° to 40°. The minimum distance to the existing ACL tunnel was measured for each pair of angles. For each patient, based on the optimal ALL orientation identified, a correlation between the ACL angle in relation to the axial plane and the distance between the ACL and the ALL tunnel was established.Results:The lowest collision rate between the ACL and ALL tunnels was measured at 0% with a 0° coronal and 40° anterior axial ALL fixation angle. In order to avoid the risk of femoral trochlea breaking when the ALL femoral tunnel is being created, it should not exceed 30 mm in length. In this context, the risk of trochlea breaking by the guide pin was evaluated at 42%. The closer the orientation of the ACL tunnel to the axis of the femoral shaft, the greater the distance to the ALL tunnel, which decreases the risk of collision of the 2 tunnels. A fixation system without guide wire should be used if trochlear breaking of the ALL guide pin is to be avoided.Conclusion:In a combined inside-out ACL and ALL reconstruction, we recommend creating the ALL tunnel with a 0° coronal and 40° axial fixation angle and the ACL tunnel with the orientation closest to the axis of the femoral shaft.

The Modified Ellison Technique: A Distally Fixed Iliotibial Band Transfer for Lateral Extra-articular Augmentation of the Knee

Lateral extra-articular augmentation (LEA) of anterior cruciate ligament reconstructions significantly reduces graft failure rates. Currently, proximally fixed LEA procedures are popular techniques. However, there are concerns about these techniques regarding anterior cruciate ligament tunnel collision, kinematic overconstraint, and increasing lateral-compartment contact forces. These issues are potentially avoided by the modified Ellison procedure, which is a distally fixed LEA technique. This article describes the surgical details of this easily reproducible technique.

An Analysis of the Femoral Drilling Angle to Avoid Tunnel Collision during Double-Bundle Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction on the Knee.

Concomitant anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction has been reported as an effective technique for providing rotational control of the knee. However, the intraoperative risk of collision with an ACL tunnel during the drilling for the femoral ALL tunnel has been described. The purpose of this study was to investigate the various femoral drilling procedures to avoid tunnel collisions during combined double-bundle ACL and ALL reconstruction. Nine cadaveric knees were used in this study. ACL drilling was performed through the anteromedial portal to footprints of the posterolateral bundle at 120° (PL120) and 135° (PL135) knee flexion and the anteromedial bundle at 120° (AM120) and 135° (AM135) knee flexion. ALL drilling was performed at 0° (Cor0-ALL) and 30° (Cor30-ALL) coronal angles using a Kirschner wire (K-wire). The distance between the ALL footprint and ACL K-wire outlets, axial angles of ALL K-wires colliding with ACL K-wires, and distances from the ALL footprint to the collision point were measured. From these values, the safe zone, defined as the range of axial angles in which no collisions or penetrations occurred, was identified by simulation of tunnels utilized for reconstruction grafts in each drilling procedure. The point-to-point distance from the ALL footprint to the K-wire outlet was significantly greater in the AM120 than the AM135 (13.5 ± 3.1, 10.8 ± 3.2 mm; p = 0.048) and in the PL135 than the PL120 (18.3 ± 5.5, 16.1 ± 6.5 mm; p = 0.005) conditions, respectively. During an ACL drilling combination of PL135/AM120, a safe zone of > 45° in Cor30-ALL was identified. With a narrow safe zone during the PL135/AM120 combination only, the risk of femoral tunnel collisions in combined double-bundle ACL and ALL reconstruction is high. AM drilling at 120° and PL drilling at > 135° knee flexion, combined with ALL drilling at 30° coronal angle and > 45° axial angle, may reduce this risk.

Proximal Tibiofibular Joint Stabilization With Concurrent Posterolateral Corner Reconstruction in Multiligamentous Knee Injury

Proximal tibiofibular joint (PTFJ) instability is a rare knee injury, accounting for less than 1% of knee injuries. It causes significant lateral sided knee pain and functional deficits and can be associated with up to 9% of multiligament knee injuries. Concurrent surgical treatment of posterolateral corner (PLC) and PTFJ instability poses technical challenges due to the limited working space of the fibula head and inherent risk of collision between grafts, bone tunnels, and implants. In this Technical Note, we detail our senior author’s technique for PTFJ reconstruction without the use of additional bone tunnels or implants in the fibula head, to reduce the risk of overcrowding and tunnel collision. ClassificationsLevel I: knee; Level II: other, proximal tibiofibular joint.

High incidence of tunnel collision in combined ACL reconstruction and LET

Aims and Objectives:Lateral extra-articular tenodesis (LET) procedures are being increasingly performed as concomitant procedures to both primary and revision intra-articular ACL reconstructions with the purpose of controlling excessive anterolateral rotatory instability and to reduce tension on the ACL graft.There is, however, a lack of evidence on benefits and pitfalls of different femoral LET attachment positions.The purpose of this study was to assess the risk of tunnel convergence in combined ACL and LET procedures comparing two different femoral attachment sites (Lemaire and MacIntosh).Materials and Methods:10 fresh-frozen cadaver knees were examined. In each specimen an anatomic ACL femoral tunnel and two LET tunnels were drilled applying the Lemaire and MacIntosh position. Following knee dissection, minimal distances between ACL and LET tunnels were directly measured on the lateral femoral cortex. Furthermore, computed tomography (CT) scans were obtained to measure inter-tunnel convergence and lateral femoral condyle (LFC) width. Based on 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 inter-tunnel 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 position was 3.1±4.6 mm and 9.8±5.4 mm, respectively.Conclusion:A high risk of tunnel convergence was 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 can significantly reduce the risk of tunnel collision. These findings help to intraoperatively raise the awareness for the risk of tunnel convergence in combined ACL and LET procedures.Adjustments on ACL reconstruction techniques and especially on the femoral fixation have to be considered when applying an additional Lemaire reconstruction.

ACL and Posterolateral Corner Injuries.

The importance of the posterolateral corner (PLC) with respect to knee stability, particularly in the setting of anterior cruciate ligament (ACL) deficiency, has become more apparent in recent years. The purposes of this article are to review the current concepts of PLC injuries and to address their role in the ACL-deficient and ACL-reconstructed knee. Recent literature demonstrates that a single staged, combined reconstruction is optimal. Studies further provide more thorough insight into avoidance of tunnel collision during the multiligament reconstruction. In total, reconstruction procedures have demonstrated successful outcomes in over 90% of patients. In summary, we report that in the setting of suspected concomitant PLC and ACL injury, it is essential to address both injuries; appreciating the local anatomy, diagnostic modalities, and surgical techniques are each crucial to achieving desirable clinical outcomes.

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.

Risk analysis of tunnel collision in combined anterior cruciate ligament and anterolateral ligament reconstructions

BackgroundTo assess the risk of tunnel collision in combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstructions. MethodsThree-dimensional (3D) CT reconstructions of 32 knees after transtibial (TT) (N = 16) or anteromedial portal (AMP) (N = 16) ACL reconstruction were used to simulate potential tunnel collision of the femoral ACL tunnel if combined with a virtual ALL reconstruction. The minimal distance between tunnels, the ALL tunnel length, and the lateral femoral condyle (LFC) width were measured. Moreover, the relationship between the ALL tunnel and the intercondylar notch, trochlear groove and posterior femoral cortex was determined. ResultsThe highest rate of tunnel collision (81%) was observed when the ALL tunnel was aimed at 20° in the coronal plane and 0° in the axial plane. However, by aiming the ALL tunnel at 0° coronal and 40° axial angulation, collision was avoided in all patients and no violation of the trochlea was observed. Tunnel collision rate was significantly higher (P = 0.002) when the ACL tunnel was drilled by the AMP technique. ConclusionsRisk of tunnel collision was significantly increased when the tunnel was drilled at 0° in the axial plane. Tunnel collision was avoided by aiming the ALL tunnel 40° anteriorly and perpendicular to the anatomical axis of the femur. A more horizontal orientation of the ACL with the AMP technique is a risk factor for tunnel conflicts. Clinical relevanceALL tunnel orientation needs to be adjusted to avoid tunnel conflicts in combined ACL–ALL reconstructions.

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.

Medial collateral ligament reconstruction using bone-patellar tendon-bone allograft for chronic medial knee instability combined with multi-ligament injuries: a new technique

BackgroundThe medial collateral ligament (MCL) is the main static stabilizer of the medial knee. The surgical treatment was recommended in cases with serious medial collateral ligament insufficiency combined with multi-ligament injuries and chronic symptomatic medial instability. Several surgical techniques have been described for the MCL reconstruction, while potential problems including donor site morbidity, complicated procedure, and high risk of femoral tunnel collision were reported. In order to minimize such potential limitations, we describe a new medial reconstruction technique for MCL injury using bone-patellar tendon-bone (BPTB) allograft.MethodsA longitudinal incision at the medial knee was made. The centers of femoral and tibial attachments were gained through repeated isometricity test. Then, the bone grooves were made around the femoral and tibial centers. The appropriate BPTB allograft was selected, and both ends were trimmed. The prepared bone blocks were embedded into the grooves and fixed with cancellous screws. The programmed rehabilitation exercises were performed after the operation.ResultsA strong graft and bone-to-bone healing on both femoral and tibial attachment sites were obtained, and femoral tunnel collision during multi-ligament reconstruction was avoided. Satisfactory valgus and rotatory stability were gained.ConclusionsThis novel MCL reconstruction technique using BPTB allograft can be safely performed, and the clinical outcome was favorable with satisfactory valgus and rotatory stability. More cases and additional follow-up results are needed to verify the overall effect of this technique.

Femoral Tunnel Drilling Angles for Posteromedial Corner Reconstructions of the Knee

To determine the best angle to drill the femoral tunnels of the superficial medial collateral ligament (sMCL) and posterior oblique ligament (POL) with concomitant posterior cruciate ligament (PCL) reconstruction to avoid either short tunnels or tunnel collisions. Eight cadaveric knees were studied. Double-bundle PCL femoral tunnels were arthroscopically drilled. Drilling of the sMCL and POL tunnels was performed in 4 different combinations of 0° and 30° axial (anteriorly directed) and coronal (proximally directed) angulations. Specimens were scanned with computed tomography to document the relations of the sMCL and POL tunnels to the intercondylar notch and PCL tunnels. A minimum tunnel length of 25 mm was required. When the sMCL femoral tunnel was drilled at 0° axial and 30° coronal (proximally directed) angulations or 30° axial (anteriorly directed) and 0° coronal angulations, the risk of tunnel collision with the PCL tunnels increased in comparison with the remaining evaluated angulations (P < .001). No POL tunnels collided with either PCL tunnel bundle with the exception of tunnels drilled at 0° axial and 30° coronal (proximally directed) angulations, which did so in 3 of 8 cases (P < .001). The minimum required tunnel length was obtained in all the sMCL and POL tunnels (P < .001 and P = .02, respectively). However, some of those angled at 0° on the axial plane violated the intercondylar notch. When one is performing posteromedial reconstructions with concomitant PCL procedures, the sMCL and POL femoral tunnels should be drilled anteriorly and proximally at both 30° axial and 30° coronal angulations. The POL femoral tunnel may also be angled 0° in the coronal plane. Tunnels at 0° axial angulations showed a shorter distance to the intercondylar notch and a higher risk of collision with the PCL tunnels. Specific drilling angles are necessary to avoid short tunnels or collisions between the drilled tunnels when sMCL and POL femoral tunnels are placed with concomitant PCL reconstruction.

How to avoid collision between PCL and MCL femoral tunnels during a simultaneous reconstruction.

The purpose of the present study was to assess the risk of femoral tunnel collisions between the medial collateral ligament (MCL) and the posterior cruciate ligament (PCL) tunnels during a simultaneous PCL and MCL reconstruction. Fourth generation medium and large synthetic femur bones were used. On each femur, a MCL tunnel and a PCL tunnel were reamed. The MCL tunnel was drilled at 0°, 20° and 40° of axial and coronal angulations. The PCL femoral tunnel was reamed to simulate two different tunnel directions that could be obtained through an inside-out and outside-in technique. Tunnels were filledwith epoxy resin augmented with BaSO4, and a multidetector CT examination of each specimen was performed. High rate of tunnel collision (62.5%) was found when the MCL femoral tunnel was reamed with a coronal angulation of 0° and 20°. The rate of tunnel collision significantly decreased (0%) when the MCL tunnel was reamed proximally with a coronal angulation of 40°. No differences were found between the two PCL tunnel directions in terms of tunnel collision. The results of this study can help surgeons to better direct the femoral MCL tunnel in order to avoid a collision between femoral tunnels during a combined MCL and PCL reconstruction. In order to minimize such potential complications, the MCL tunnel should be created limiting the axial angulation and it should be drilled with a proximal angulation from 20° to 40°, depending on the medial condyle width.