Anterior Cruciate Ligament Footprint Research Articles

Radiographic Anatomy of the Native Anterior Cruciate Ligament: a Systematic Review.

In an attempt to improve the accuracy and reproducibility of tunnel positioning, radiographs are being analyzed in an attempt to recreate the native anatomy of the ACL. Understanding the native ACL radiographic anatomy is an essential prerequisite to understand the relevance of postoperative tunnel position. We performed a systematic review of the literature to delineate the radiographic location of the native ACL femoral and tibial footprints. A search was performed in March 2014 in PubMed, the Cochrane Collaboration Library, and EMBASE to identify all studies that evaluated the native anterior cruciate ligament (ACL) anatomy on radiographs. Various measurement methods were used in each study, and averages were obtained of the data from studies with the same measurement methods. Fifteen papers were identified (which included data on 177 femora and 207 tibiae in total). Evaluation of the femoral footprint using the quadrant method on lateral knee radiographs showed that the average percent distance location of the anteromedial (AM) bundle and posterolateral (PL) bundle was 22.8% (95% confidence interval (CI) 16.59-28.90) and 32.5% (95% CI 27.71-37.26) from the posterior condyle, respectively, and 23.2% (95% CI 19.52-26.94) and 50.0% (95% CI 46.16-53.76) from Blumensaat's line, respectively. Using the Amis and Jacob method, the tibial footprint on the lateral knee radiograph average percent distances was 35.1% (95% CI 34.46-35.72) for the center of the AM bundle and 47.3% (95% CI 41.69-52.95) for the center of the PL bundle of the ACL. The femoral and tibial ACL footprints on the anteroposterior (AP) views of the knee were not well delineated by these studies. The information presented in this systematic review offers surgeons another important tool for accurate ACL footprint identification.

Optimal entry position on the lateral femoral surface for outside-in drilling technique to restore the anatomical footprint of anterior cruciate ligament.

To investigate the optimal starting points for drilling on the lateral femoral condyle for better coverage of the anatomical footprint of the anterior cruciate ligament (ACL) using the outside-in (OI) technique in a single-bundle ACL reconstruction. Femoral tunnel drilling was simulated on three-dimensional bone models from 40 subjects by connecting the centre of the ACL footprint with various points on the lateral femoral surface. The percentage of the femoral footprint covered by apertures of the virtual tunnel sockets with 9mm diameter was calculated for each tunnel. The mean percentages of the femoral footprint covered by the apertures of the virtual tunnel sockets were significantly higher when drilled at 2 and 3cm from the lateral epicondyle on a 45° line and a 60° line anterior from the proximal-distal axis than the other points. However, articular cartilage damage was occurred in nine subjects at 3cm on a 60° line and eight subjects at 3cm on a 45° line. Posterior wall blowout occurred in five subjects at 3cm on a 45° line. Thus, OI drilling at 3cm from the epicondyle has a risk of these complications. During the OI drilling of the femoral tunnel, connecting the centre of the anatomical footprint of the ACL and the entry drilling point at 2cm from the lateral epicondyle on between the 45° line and the 60° line anterior from the proximal-distal axis provides an oval-shaped socket aperture that covers and restores the native ACL footprint as nearly as possible. III.

Radiologic and Clinical Evaluation of Anatomic and Transtibial ACL Reconstruction in a Population Excluding Professional Athletes

Objectives:Two different approaches for drilling the femoral tunnel are commonly used in single-bundle anterior cruciate ligament (ACL) reconstruction: creating the femoral tunnel through the tibial tunnel or drilling the tunnel through a low anteromedial portal. The purpose of this retrospective study was to compare the radiological and clinical outcomes of hamstring ACL reconstruction using the transtibial (TT) versus the anteromedial portal (AM) technique for drilling the femoral tunnel by two different surgeons in non-professional athletes.Methods:Using the elevator system with hamstring tendons, single-bundle ACL reconstruction was applied to 24 patients with the TT technique and to 15 patients with the AM technique. Radiological outcome was evaluated by the postoperative X-rays and MRI images at the 6-9 month and clinical outcomes by the modified Cincinnati Knee Score. The angle made by the tunnel with the anatomic axis of the femur (FTA) and the angle made by the tunnel with the anatomic axis of the tibia (TTA) were examined on direct radiographs and the angular difference between the tunnels was evaluated. On MRI, evaluation was made of the anterior length in the sagittal plane of the exit point of the tibial tunnel in the joint (TAS) in ratio to the whole plateau (TSR) and the posterior length in the sagittal plane of the entrance point of the femoral tunnel in the femoral lateral condyle (FPS) in ratio to the anterior posterior diameter of the whole condyle (FCR) and the height of the lateral condyle location in the sagittal plane (FH).Results:The FH height ratio of the TT group was statistically significant when compared to the AM group (p<0.01). No statistically significant difference was found between the groups in respect of FPS (p>0.05). The mean femoral tunnel angle of the AM group was statistically significant compared to that of the TT group (p<0.01). The mean tibial tunnel angle of the TT group was statistically significant compared to that of the AM group (p<0.01). The angular difference of the AM group was statistically significant compared to that of the TT group (p<0.01). In both the AM and TT groups, the increase seen in the postoperative clinical scores compared to the preoperative scores was determined to be statistically significant (p<0.01). No statistically significant relationship was determined in either the AM group or the TT group between the postoperative clinical scores and the femoral tunnel angle, the tibial tunnel angle and the angular difference (p>0.05).Conclusion:When using a transtibial drilling technique, the location of the femoral tunnel is restricted by the angulation of the tibial tunnel in the coronal plane and may lead to a high placement of the femoral tunnel in a non-anatomical position. The use of the anteromedial portal (AMP) for the femoral drilling provides the surgeon with more freedom to anatomically place the tunnel in the natural femoral ACL footprint, thus improving rotational stability. In this early stage study of individuals not participating in professional sports, although a significant difference was seen in favour of the anatomic group, in the radiological measurements between the anatomic and transtibial groups, no significant difference was determined in respect of clinical results. This can be considered to be due to a low requirement for rotational stability in individuals who do not participate sports.

Consequences of Tibial Tunnel Reaming on the Meniscal Roots During Cruciate Ligament Reconstruction in a Cadaveric Model, Part 1

Background: The current standard for treating complete tears of the anterior cruciate ligament (ACL) is reconstruction, which requires reaming a tibial tunnel. Based on recent anatomic and biomechanical studies, this reconstruction tunnel may cause injuries to the anterior meniscal root attachments. Purpose/Hypothesis: The purpose was to determine if injuries occurred to the anteromedial (AM) and anterolateral (AL) meniscal root attachments because of reaming a tibial reconstruction tunnel in the anatomic center of the ACL footprint. It was hypothesized that tibial tunnel reaming for ACL reconstruction would result in significant decreases in the attachment area and in ultimate failure strength for the AL root. Study Design: Controlled laboratory study. Methods: Twelve matched pairs of human cadaveric knees were tested. One knee from each pair remained intact, while the contralateral knee was reamed with a tibial tunnel for an anatomic ACL reconstruction. The attachment areas of the anterior meniscal roots were measured with a coordinate measuring device before and after tunnel reaming. The anterior meniscal roots were then pulled to failure with a dynamic tensile testing machine. Results: There was a significant mean decrease in the attachment area for the AL root (%Δ, 38%; 95% CI, 25-51) after ACL tunnel reaming compared with the intact state (P = .003). The mean ultimate failure strength of the native AL root (mean, 610 N; 95% CI, 470-751) was significantly stronger (P = .015) than that of the AL root with a reamed ACL reconstruction tunnel (mean, 506 N; 95% CI, 353-659). Tunnel reaming did not significantly affect the AM root attachment area or ultimate failure strength. Conclusion: Tibial tunnel reaming during anatomic single-bundle ACL reconstruction significantly decreased the AL meniscal root attachment area and ultimate failure strength. The AM root was not significantly affected by reaming of the ACL reconstruction tunnel. Future studies should investigate the clinical importance of these iatrogenic injuries to the AL root. Clinical Relevance: The ACL reconstruction tunnels reamed in the center of the ACL tibial footprint caused a significant decrease in the attachment area and ultimate strength of the AL meniscal root attachment. Clinically, repositioning guide pins placed in the lateral aspect of the ACL attachment before tibial tunnel reaming may minimize iatrogenic injuries to the AL meniscal root attachment.

Quantitative topographic anatomy of the femoral ACL footprint: a micro-CT analysis.

The femoral footprint of the anterior cruciate ligament (ACL) is a much-studied anatomic structure, predominantly due to its importance during ACL reconstruction surgery. A new technique utilising high-resolution micro-computed tomography (micro-CT) is described, allowing detailed three-dimensional (3D) quantitative analysis of this structure. Seven cadaveric knees were scanned using micro-CT, yielding 3D data with a reconstructed voxel size of 60μm. A novel method of 3D surface extraction was developed and validated, facilitating both qualitative observation of surface details and quantitative topographic assessment using colour-coded relief maps. Images were displayed on an immersive 3D visualisation wall, and ten experienced ACL clinicians were surveyed as to the presence and morphology of osseous landmarks, providing qualitative assessment of whether such features can be reliably identified for navigation during surgery. Both quantitative analysis and qualitative assessment of the footprints in this study showed significant variability in the presence and morphology of osseous landmarks, with the lateral intercondylar ridge being objectively present in four out of seven relief maps, although reportedly seen in six out of seven cases in the qualitative study, suggesting an element of subjectivity and interpretation. This is the first study to utilise micro-CT in the study of ACL anatomy.

Effect of tibial tunnel diameter on femoral tunnel placement in transtibial single bundle ACL reconstruction.

The purpose of this study was to identify the impact of tibial reamer size and placement on the position of femoral tunnel placement via a transtibial approach for anterior cruciate ligament (ACL) reconstruction. Eight cadaveric knee specimens were fixed to a stationary table at 90° of flexion and neutral rotation. After removing the anterior capsule and patella, native joint anatomy was recorded with a digitizer (MicroScribe™; CNC Services, Amherst, VA) accurate to 0.05 mm. Tibial and femoral tunnels were drilled via a transtibial ACLR technique using the optimal tibial starting point described by Piasecki et al. On the tibial side, tunnels were drilled progressively with 6-, 7-, 8-, 9-, 10-, and 11-mm reamers. After each reaming, a beath pin was placed in the posterior aspect of the tibial tunnel, positioned relative to the native anatomic ACL femoral footprint, and digitized. Rhino software (McNeel, Seattle, WA) was used to geometrically determine the center of the native femoral footprint and measure in millimeters the relationship of this point with the femoral position achieved using a 7-mm offset femoral guide with each tibial tunnel size. The surface areas of each tibial and femoral insertion were measured using the insertional periphery data recorded with the digitizer. Statistical analysis of continuous variable data was performed with t tests; P values below 0.05 were deemed significant. The center of the femoral ACL footprint was reached with a 9-mm tibial tunnel in six knees, and with an 8-mm tunnel in two knees. A 6- or 7-mm tibial tunnel did not allow for anatomic positioning in any specimen, with femoral positioning significantly more superior than that achieved with a 9-, 10-, or 11-mm tibial tunnel (P < 0.01). The 6- and 7-mm tunnels produced errors of 4.6 ± 1.6 and 2.9 ± 0.5 mm, respectively. After use of the 11-mm tibial reamer, the average tibial tunnel length was 32.1 ± 2.6 mm. Limitations of a transtibial ACLR technique may result in non-anatomic femoral tunnel placement with tibial tunnel sizes smaller than 9 mm. However, tibial tunnels placed in the proximal entry position with at least a 9-mm tunnel size allowed anatomic femoral tunnel placement via a transtibial approach.

Origin of the anterior cruciate ligament and the surrounding osseous landmarks of the femur.

The aims of this study were to evaluate the discernibility of the LIR (lateral intercondylar ridge) and the LBR (lateral bifurcate ridge) and show their reliability in femoral tunnel placement in ACL (anterior cruciate ligament) reconstruction. Additionally, their position to the femoral axis, their course, and the ACL footprint were analyzed. For this study, 235 human femora were evaluated. Of these, 166 specimens originated from the Museum of Natural History (group A), and 69 were obtained from fixed cadavers at the Anatomic Institute (group B). The femoral footprint and the osseous landmarks were identified macroscopically and labeled in the photographs. A coordinate system was outlined, and the dimensions, position, and orientation of the femoral footprint of the ACL were measured. The LBR was found in 24.7% of the specimens in group A and in only 13.2% of the specimens in group B. The LIR was found in 97.9% and 85.3% of the specimens in groups A and B, respectively. The area of the ACL footprint was 127.21 ± 32.54 mm(2) in group A and 119.58 ± 34.84 mm(2) in group B. The shapes and angles of the osseous landmarks near the line of Blumensaat were highly variable. The LBR is an unreliable intraoperative landmark for arthroscopic ACL reconstruction due to its low incidence. Other anatomical structures, such as the LIR or the osteochondral border, may be more helpful and reliable landmarks to guide proper tunnel placement.

ACL reconstruction

An anterior cruciate ligament (ACL) tear is one of the most common injuries seen by orthopaedic surgeons and is the most common complete ligamentous injury in the knee. Recent reports indicate that over 250,000 ACL reconstructions are performed each year in United States. Recent studies have emphasized the importance of anatomic tunnel placement during ACL reconstruction in an effort to restore normal knee kinematics, stability, and improve outcomes. ACL reconstruction was first described as an open technique, followed shortly by the outside-in, two-incision techniques, both of which provided relatively anatomic reconstruction methods. The transtibial technique became popular with the advent of offset guides early in the 1990s. The current trend appears to be shifting back towards anatomic reconstruction of the ACL through outside-in drilling or anteromedial-portal drilling. The objective of anatomic single- or double-bundle reconstruction is to restore a maximal percentage of the native ACL footprint attachment on the femur and tibia and thereby stability of the knee. This article discusses the most up-to-date literature on the anatomic considerations in ACL reconstruction, with a primary emphasis on restoring the anatomic footprint.

Ribbon like appearance of the midsubstance fibres of the anterior cruciate ligament close to its femoral insertion site: a cadaveric study including 111 knees.

Purpose Recently, the configuration of the anterior cruciate ligament (ACL) from its direct femoral insertion to midsubstance was found to be flat. This might have an important impact for anatomical ACL reconstruction. The purpose of this anatomical study was to evaluate the macroscopic appearance of the ACL from femoral to midsubstance.MethodsThe ACL was dissected in 111 human fresh frozen cadaver knees from its femoral insertion to midsubstance, and the shape was described. The anatomical findings were documented on digital photographs and on video. Thirty knees were sent for computed tomography (CT), magnetic resonance imaging (MRI) and histology of the femoral ACL insertion.ResultsTwo millimetres from its direct femoral insertion, the ACL fibres formed a flat ribbon in all dissected knees without a clear separation between AM and PL bundles. The ribbon was in exact continuity of the posterior femoral cortex. The width of the ribbon was between 11.43 and 16.18 mm and the thickness of the ACL was only 2.54–3.38 mm. 3D CT, MRI and the histological examination confirmed above findings.ConclusionThis is a detailed anatomical study describing the ribbon-like structure of the ACL from its femoral insertion to midsubstance. A key point was to carefully remove the surface fibrous membrane of the ACL. A total of 2–3 mm from its bony femoral insertion, the ACL formed a flat ribbon without a clear separation between AM and PL bundles. The ribbon was in exact continuity of the posterior femoral cortex. The findings of a flat ligament may change the future approach to femoral ACL footprint and midsubstance ACL reconstruction and to graft selection.Electronic supplementary materialThe online version of this article (doi:10.1007/s00167-014-3146-7) contains supplementary material, which is available to authorized users.

Proportional evaluation of anterior cruciate ligament footprint size and knee bony morphology.

The purpose of this study was to reveal the correlation in size between the native anterior cruciate ligament (ACL) footprint and the femoral intercondylar notch and the tibia plateau, and to calculate the proportion in size between the ACL footprint and knee bony morphology. Twenty-six non-paired human cadaver knees were used. All soft tissues around the knee were resected except the ACL. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch. The ACL was carefully dissected, and the periphery of the ACL insertion site was outlined on both the femoral and tibial sides. An accurate lateral view of the femoral condyle and an axial view of the tibial plateau were photographed with a digital camera, and the images were downloaded to a personal computer. The size of the femoral and tibial ACL footprints and the area of the lateral wall of the intercondylar notch and the tibia plateau were measured with Image J software (National Institution of Health). The sizes of the native femoral and tibial ACL footprints were 69.8 ± 25 and 133.8 ± 31.3 mm(2), respectively. The areas of the lateral wall of the intercondylar notch and the tibia plateau were 390.5 ± 70.5 and 2,281.7 ± 377.3 mm(2), respectively. The femoral ACL footprint area and the area of the lateral wall of the femoral intercondylar notch (Pearson's correlation coefficient = 0.603, p = 0.001), and the tibial ACL footprint area and the area of the tibia plateau (Pearson's correlation coefficient = 0.452, p = 0.02) both showed significant correlation. The femoral ACL footprint was 17.8 ± 4.9 %, the size of the lateral wall of the femoral intercondylar notch, and the tibial ACL footprint was 5.9 ± 1.3 %, the size of the tibia plateau. For clinical relevance, the femoral ACL footprint is approximately 18 %, the size of the intercondylar notch, and the tibial ACL footprint is approximately 6 %, the size of the tibia plateau. It might be possible to predict the size of the ACL measuring these parameters preoperatively.

Femoral Tunnel Apertures on the Lateral Cortex in Anterior Cruciate Ligament Reconstruction: An Analysis of Cortical Button Fixation

If the aperture of the oval-shaped femoral tunnel on the lateral cortex becomes bigger than half the size of the cortical button, the risk of fixation failure increases. This study investigated the effect of the location of the entry point and diameter of the femoral tunnel on the length of the major axis of the tunnel aperture in anterior cruciate ligament (ACL) reconstruction using an outside-in technique. Simulation of femoral tunnel drilling was performed on computed tomography (CT)-based 3-dimensional (3D) bone models obtained from 40 participants. The tunnel connected the center of the ACL footprint and various points on the lateral femoral surface. The diameter of the tunnel was set at 4.2 mm, 5.2 mm, or 6 mm, depending on the commercially available outside-in surgical systems (Arthrex, Naples, FL and Smith & Nephew, Andover, MA). The length of the major axis of the oval-shaped aperture on the lateral femoral surface was measured. When the tunnel was introduced at 2 cm from the lateral epicondyle in a 45° anteroproximal direction, the major axis was lengthened to 130.7% ± 9.0% (P < .001) of the tunnel diameter, and it was more than 6.5 mm in 65% of participants in whom a 5.2-mm-diameter tunnel was drilled. When the entry point was 3 cm from the lateral epicondyle, 60% of participants had an oval-shaped aperture with a major axis of more than 6.5 mm, even though the diameter of the tunnel was only 4.2 mm. The risk of fixation failure of a cortical button increases if the entry point for drilling is 2 cm or further from the lateral epicondyle and the tunnel diameter is more than 5mm. This study indicates the potential risk of cortical button fixation failure caused by an oval tunnel aperture on the lateral femoral surface in ACL reconstruction using the outside-in technique.

Size correlation between the tibial anterior cruciate ligament footprint and the tibia plateau

The purpose of this study was to reveal the correlation between the size of the native anterior cruciate ligament (ACL) footprint and the size of the tibia plateau. Twenty-four non-paired human cadaver knees were used. All soft tissues around the knee were resected except the ACL. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch. The ACL was carefully dissected, and the periphery of the ACL insertion site was outlined on both the femoral and tibial sides. An accurate lateral view of the femoral condyle and the tibial plateau was photographed with a digital camera, and the images were downloaded to a personal computer. The size of the femoral and tibial ACL footprints, and anterior-posterior (AP) and medial-lateral (ML), lengths of the tibia plateau and area of tibia plateau were measured with Image J software (National Institution of Health). The sizes of the native femoral and tibial ACL footprints were 72.3±24.4 and 134.1±32.4mm(2), respectively. The AP lengths of the whole, medial and lateral facet of the tibia plateau were as follows: 44.5±4.1, 40.8±4.1 and 36.8±4mm, respectively. The ML length of the tibia plateau was 68.3±5.5mm. Total area of tibia plateau was 2,282.9±378.7mm(2). The AP length of the lateral facet of the tibia plateau (Pearson's correlation coefficient=0.508, p=0.011) and the total area of tibia plateau (Pearson's correlation coefficient=0.442, p=0.031) were significantly correlated with the size of the tibial ACL footprint. For clinical relevance, the AP length of lateral facet of the tibia plateau and total area of tibia plateau are significantly correlated with the size of the tibial ACL footprint. It might be possible to predict the size of the ACL measuring these parameters.

Evaluation and Comparison of Femoral Tunnel Placement During Anterior Cruciate Ligament Reconstruction Using 3-Dimensional Computed Tomography: Effect of Notchplasty on Transtibial and Medial Portal Drilling.

Background:Advocates of medial portal drilling claim that the transtibial technique results in a more vertical positioning of the graft, which could lead to subsequent failure and/or a residual pivot shift on postoperative examination. However, advocates of transtibial drilling state that with appropriate placement and adequate notchplasty, their technique places the graft in a more anatomically correct position on the wall, negating the resultant potential for pivot shift and early postoperative failure.Hypothesis:Transtibial femoral drilling can adequately reproduce the femoral origin of the anterior cruciate ligament (ACL) and place the graft in an anatomical position equivalent to medial portal drilling.Study Design:Controlled laboratory study.Methods:Ten matched-pair cadaveric knees (N = 20) were scanned using computed tomography (CT), and 3-dimensional images of the native ACL origin were reconstructed. The matched pairs were then randomized into transtibial and medial portal groups. The femoral tunnel was drilled in each knee according to group. A bamboo skewer was placed in the femoral tunnel, and the knees underwent a second CT scan. Arthroscopic notchplasty was performed, and the femoral tunnels were redrilled. Radiographs confirmed placement, and the post-notchplasty tunnel was reamed with a 4-mm reamer. The knees underwent a third CT scan. CT scans compared femoral tunnel placement with the native ACL footprint before and after notchplasty.Results:The post-notchplasty transtibial group revealed an average of 68.3% coverage of the native ACL femoral origin. The medial portal group revealed an average of 60.8% coverage, with 1 instance of perforation of the posterior cortex. There were no instances of perforation in the transtibial group.Conclusion:Both drilling techniques place the graft in an anatomically correct position.Clinical Relevance:Transtibial drilling of the femur can adequately place the entry tunnel at the origin of the ACL’s native footprint.

Anterior Cruciate Ligament Tunnel Placement

The purpose of this cadaveric study was to analyze variation in anterior cruciate ligament (ACL) tunnel placement between surgeons and the influence of preferred surgical technique and surgeon experience level using three-dimensional (3D) computed tomography (CT). In this study, 12 surgeons drilled ACL tunnels on six cadaveric knees each. Surgeons were divided by experience level and preferred surgical technique (two-incision [TI], medial portal [MP], and transtibial [TT]). ACL tunnel aperture locations were analyzed using 3D CT scans and compared with radiographic ACL footprint criteria. The femoral tunnel location from front to back within the notch demonstrated a range of means of 16% with the TI tunnels the furthest back. A range of means of only 5% was found for femoral tunnel low to high positions by technique. The anterior to posterior tibial tunnel measure demonstrated wider variation than the medial to lateral position. The mean tibial tunnel location drilled by TT surgeons was more posterior than surgeons using the other techniques. Overall, 82% of femoral tunnels and 78% of tibial tunnels met all radiographic measurement criteria. Slight (1-7%) differences in mean tunnel placement on the femur and tibia were found between experienced and new surgeons. The location of the femoral tunnel aperture in the front to back plane relative to the notch roof and the anterior to posterior position on the tibia were the most variable measures. Surgeon experience level did not appear to significantly affect tunnel location. This study provides background information that may be beneficial when evaluating multisurgeon and multicenter collaborative ACL studies.

Anatomic Single Bundle Anterior Cruciate Ligament Reconstruction Using Two Cross Pins: Cadaveric Study and Clinical Application

Background: Anatomic single bundle is a widely accepted technique for anterior cruciate ligament (ACL) reconstruction. The research question: are transverse pins safe to fix the ACL graft on the femoral side in anatomic single bundle ACL reconstruction? Material and Methods: Ten cadaveric femoral dry bones were tested in this study. Thirty mm long sockets were prepared in the center of the anatomic ACL footprints. Transverse pin guide for soft tissue graft was used to prepare pin sites through the femoral sockets using three different positions. The positions (A) and (B) had a lateral entry point and differ in their inclination in relation to the joint line; while (A) has a 15° open laterally plane, (B) has a 15° closed laterally. The last position (C) had a medial entry point for the transverse pins. The relations of the transverse pins to the anatomic landmarks (lateral epicondyle and articular cartilage) in addition to the path of the pins within the femoral sockets were recorded. Results: Pins inserted while the guide in position (A) crossed the center of the femoral sockets and were fully seated within the bone of the distal femur. Distal pins inserted through inclination (B) were found to penetrate the posterior cortex of the distal femur proximal to the lateral femoral condyle. Pins inserted from the medial side (C) achieved central position through the femoral tunnel. The entry point for transverse pins through lateral entry points was very close to the attachment of the lateral collateral ligament at the lateral epicondyle while medial entry point avoided important structures. Conclusion: Transverse pins inserted through the lateral entry point carry the risk of penetrating the posterior cortex of the femur and/or damage the attachment of the lateral collateral ligament. Medial entry point may give a safer approach but needs further adjustments of the guides and clinical trials of the technique.

Physeal-Sparing Technique for Femoral Tunnel Drilling in Pediatric Anterior Cruciate Ligament Reconstruction Using a Posteromedial Portal

Pediatric anterior cruciate ligament (ACL) tears present a technical dilemma for orthopaedic surgeons. Multiple surgical techniques have been described to protect the distal femoral and proximal tibial physes. We present an ACL reconstruction technique performed on a 12-year-old girl with open physes who sustained an ACL tear after a noncontact twisting injury while playing soccer. A hamstring autograft reconstruction was performed by use of a posteromedial portal to drill the femoral tunnel in an all-epiphyseal fashion at the anatomic footprint of the native ACL. This case provides a new surgical technique to achieve anatomic fixation for ACL reconstruction in a skeletally immature individual using a posteromedial portal to drill a physeal-sparing lateral femoral tunnel for anatomic ACL reconstruction. This advancement may make drilling the femoral tunnel less technically challenging compared with other proposed methods while maintaining the lateral wall of the distal femur.

Three-dimensional computed tomography evaluation of anterior cruciate ligament footprint for anatomic single-bundle reconstruction

Femoral and tibial footprint coordinates have been well studied in double-bundle anterior cruciate ligament (ACL) reconstruction. However, in a single-bundle reconstruction approach, the central coordinate of femoral and tibial footprints have not been determined. The purpose of this study was to describe the central point locations of the ACL footprints visualized by three-dimensional computed tomography (3D CT) images and analysed by the quadrant method. Eight cadaveric knees were dissected, and the central points of ACL femoral and tibial footprints were marked and analysed using 3D CT images. In the present study, the means (and standard deviation) of ACL femoral footprint dimensions were in the ventral-dorsal plane and in the cranial-caudal plane 9.4 ± 0.8 and 15.6 ± 0.9 mm, respectively. In the tibial side, the means of ACL footprint dimensions were in the anterior-posterior and in the medial-lateral 18.5 ± 1.9 and 15.5 ± 1.0 mm, respectively. In the tomographic analyses, the means of femoral central location coordinates in the ventral-dorsal (y) and in the cranial-caudal (x) axes were 35.3 ± 4.5 and 30.0 ± 1.6 %, respectively. The means of tibial central location coordinates were in the anterior-posterior (y) and in the medial-lateral (x) axes, respectively: 40.5 ± 5.3 and 50.2 ± 1.3 %, respectively. These computed tomographic coordinates might help future studies as a reference on ACL single-bundle anatomic reconstruction, with respect to the management of ACL revision surgery or in symptomatic patients after ACL reconstruction. Improvements in three-dimensional image acquisition could facilitate its intraoperative applicability in the coming years.

Effect of Medial-Lateral Position of the Tibial Anteromedial Bundle Tunnel on Knee Biomechanics

Effect of Medial-Lateral Position of the Tibial Anteromedial Bundle Tunnel on Knee Biomechanics

Coverage of the Anterior Cruciate Ligament Femoral Footprint Using 3 Different Approaches in Single-Bundle Reconstruction

Background: Performing a single-bundle anterior cruciate ligament (ACL) reconstruction within the femoral footprint is important to obtain a functional graft and a stable knee. Hypothesis: There will be a significant difference in the ability of 3 ACL reconstruction techniques to reach and cover the native femoral footprint. Study Design: Controlled laboratory study. Methods: The percentage of the ACL footprint covered by the femoral tunnel was compared after 3 different techniques to target the footprint: transtibial (TT), inside-out/anteromedial (IO), and outside-in/transfemoral (OI). Fourteen cadaveric knee specimens with a mean age of 67.5 years were used. For each knee, the TT technique utilized a 7.5-mm offset guide, the IO technique was performed through an accessory anteromedial portal, and the OI technique was carried out through the femur from the external wall of the lateral condyle. Entry points in the footprint were spotted with markers, and orientations (sagittal and frontal) of each drill guide were noted. The distal femurs were sawed and scanned, and 3-dimensional image reconstructions were analyzed. The virtual drilled area (reamer diameter, 8 mm) depending on the entry point and the sagittal/frontal orientation of the drill guide was calculated and reported for each of the 3 techniques. The distance from the tunnel center to the ACL center, percentage of the femoral tunnel within the ACL footprint, and percentage of the ACL footprint covered by the tunnel were calculated and statistically compared (analysis of variance and t test). Results: The average distance to the native femoral footprint center was 6.8 ± 2.68 mm for the TT, 2.84 ± 1.26 mm for the IO, and 2.56 ± 1.39 mm for the OI techniques. Average percentages of the femoral tunnel within the ACL footprint were 32%, 76%, and 78%, and average percentages of the ACL footprint covered by the tunnel were 35%, 54%, and 47%, for the TT, IO, and OI techniques, respectively. No significant difference was observed between the IO and OI techniques (P = .11). The TT approach gave less satisfactory coverage on all testing criteria. Conclusion: The IO and OI techniques allowed for creation of a tunnel closest to the ACL femoral footprint center. Despite this fact and even if the average percentage of the drilled area included in the femoral footprint was close to 80% for these 2 techniques, the average percentage of the ACL footprint covered by the tunnels was <55% for all 3 techniques. Coverage of the ACL footprint depended on the entry point, orientation, and diameter of the drilling but also on the size of the footprint. Clinical Relevance: To improve the coverage of the native femoral footprint with a single-bundle graft, in addition to the entry point it may also be necessary to consider the orientation of the drilling to increase the dimensions of the area while respecting the anatomic constraints of the femoral bone and graft geometry.

A Rare Technical Complication Causing ACL Graft Failure: Aberrant Femoral Tunnel Trajectory and Posterolateral Corner Compromise: A Case Report.

In order to o reproduce normal joint kinematics of the knee following anterior cruciate ligament (ACL) injury, anatomic reconstruction has been advocated1-6. This can be achieved best by recreating the native ACL footprints. Matching the location of the intra-articular apertures of the femoral and tibial tunnels to the anatomic footprints of the native ACL has been reported to be accomplished most accurately with techniques other than traditional transtibial drilling7-11. In the pediatric population, the trajectory of the femoral tunnel is more heavily scrutinized because of its relationship to the distal femoral physis. However, in adults, clinical evidence is sparse regarding the appropriate tunnel trajectory. Cadaveric studies detailing the anatomic relationships of the femoral tunnel to the structures of the lateral aspect of the knee also have been reported12-16. The proximity of the lateral exit point of the femoral tunnel to critical lateral structures placed with an independent tunnel drilling technique has been shown to be a potential source of iatrogenic injury15. To our knowledge, there are no reports in the literature of injury to the posterolateral corner (PLC) as a result of femoral tunnel placement in ACL reconstruction. We present a case of PLC compromise and ACL graft failure following aberrant femoral tunnel placement in a revision ACL reconstruction. The patient was informed that data concerning the case would be submitted for publication, and he provided consent. A twenty-one-year-old male intercollegiate football player presented after sustaining a knee injury while performing a lateral shuffling drill during an off-season workout. He had been treated by two different orthopaedists and had undergone two surgeries on the affected knee for treatment of ACL insufficiency prior to this most recent injury. Three years prior to presentation, he had ruptured his …