Femoral Tunnel Aperture Research Articles

Effects of femoral bone tunnel characteristics on graft-bending angle in double-bundle anterior cruciate ligament reconstruction: a comparison of the outside-in and transportal techniques.

Bone tunnel creation techniques influence the 3-dimensional (3D) position of bone tunnels and graft-bending angle in anterior cruciate ligament (ACL) reconstruction. This study assessed graft-bending angle and 3D characteristics of femoral bone tunnels and compared them between outside-in (OI) and transportal (TP) techniques. Participants comprised 64 patients who underwent anatomic double-bundle ACL reconstruction, allocated to OI and TP groups (n=32 each). The graft orientation plane exhibiting the largest graft-bending angle at the femoral tunnel aperture with the knee in extension was reconstructed from CT data using 3D imaging software. In this plane, graft-bending angle was compared between the OI and TP techniques. Although positionings of the intra-articular apertures of the femoral and tibial bone tunnels were similar, several spatial parameters of bone tunnels differed between techniques. Graft-bending angles of both anteromedial and posterolateral bundles were significantly more acute with the OI technique than with the TP technique. On coronal-plane CT, angle of the bone tunnel axis relative to the distal condylar axis correlated negatively with graft-bending angle, while in the axial plane, angle of the bone tunnel axis relative to the posterior condylar axis correlated positively with graft-bending angle. Lysholm score, pivot shift test, and anteroposterior laxity at >2.5-year follow-up demonstrated no significant differences between techniques. Different bone tunnel directions in OI and TP techniques substantially affected graft-bending angle , despite similar positionings of the intra-articular apertures. Graft-bending angle with the OI technique was acute, but risk of posterior blowout of the lateral femoral condyle was decreased. Surgeons should create the femoral tunnel while considering an obtuse graft-bending angle without increasing the risk of posterior blowout. III.

Femoral and Tibial Graft Tunnel Parameters After Transtibial, Anteromedial Portal, and Outside-In Single-Bundle Anterior Cruciate Ligament Reconstruction

Background: Anatomic graft tunnel placement is recommended in anterior cruciate ligament (ACL) reconstruction to restore knee joint stability and function. Transtibial (TT), anteromedial portal (AMP), and outside-in (OI) retrograde drilling surgical techniques have been described for tibial and femoral bone tunnel preparation. Purpose/Hypothesis: The purpose of this study was to evaluate the bone tunnel parameters and compare the ability of 3 different surgical techniques to achieve placement of the ACL femoral and tibial bone tunnels at the center of the native ACL femoral and tibial attachment sites. The hypothesis was that tunnel placement using an AMP or OI technique would result in optimized tunnel parameters and more closely reconstruct the center of the native ACL femoral attachment site. Study Design: Cohort study; Level of evidence, 3. Methods: The study population consisted of 100 patients undergoing anatomic single-bundle ACL reconstruction using multiple-stranded hamstring tendon grafts. In group 1 (n = 36), the femoral tunnel was drilled using a TT surgical technique; in group 2 (n = 32), the femoral tunnel was drilled through an AMP; and in group 3 (n = 32), the femoral tunnel was created by use of an OI technique with retrograde drilling. Computed tomography (CT) scans were obtained postoperatively, and characteristics of femoral and tibial tunnel apertures were correlated to femoral and tibial measurement grid systems. The position of the resulting tibial and femoral bone tunnels for each group was compared with the center of the native ACL attachment sites. Results: There were statistically significant differences (P < .05) for the ACL femoral tunnel between the 3 groups with respect to intercondylar height, total tunnel length, graft fixation length, tunnel axis, and tunnel entry angle. Statistically significant differences (P < .05) were found for the ACL tibial tunnel with respect to anteroposterior tunnel position and sagittal tunnel axis between the TT and both the OI and AMP techniques. The OI surgical technique produced more oblique and anatomically correct femoral tunnel apertures and longer femoral tunnel lengths compared with the AMP technique. Both AMP and OI techniques resulted in a more precise replication of intercondylar tunnel depth and height. There was no statistically significant difference for graft fixation length between the AMP and OI techniques. Conclusion: The AMP and OI surgical techniques were superior in positioning the ACL femoral tunnel at the center of the native ACL attachment site compared with the TT technique. An acceptable graft fixation length was obtained for all 3 surgical techniques.

Comparison of femur tunnel aperture location in patients undergoing transtibial and anatomical single-bundle anterior cruciate ligament reconstruction

Although three-dimensional computed tomography (3D-CT) has been used to compare femoral tunnel position following transtibial and anatomical anterior cruciate ligament (ACL) reconstruction, no consensus has been reached on which technique results in a more anatomical position because methods of quantifying femoral tunnel position on 3D-CT have not been consistent. This meta-analysis was therefore performed to compare femoral tunnel location following transtibial and anatomical ACL reconstruction, in both the low-to-high and deep-to-shallow directions. This meta-analysis included all studies that used 3D-CT to compare femoral tunnel location, using quadrant or anatomical coordinate axis methods, following transtibial and anatomical (AM portal or OI) single-bundle ACL reconstruction. Six studies were included in the meta-analysis. Femoral tunnel location was 18% higher in the low-to-high direction, but was not significant in the deep-to-shallow direction, using the transtibial technique than the anatomical methods, when measured using the anatomical coordinate axis method. When measured using the quadrant method, however, femoral tunnel positions were significantly higher (21%) and shallower (6%) with transtibial than anatomical methods of ACL reconstruction. The anatomical ACL reconstruction techniques led to a lower femoral tunnel aperture location than the transtibial technique, suggesting the superiority of anatomical techniques for creating new femoral tunnels during revision ACL reconstruction in femoral tunnel aperture location in the low-to-high direction. However, the mean difference in the deep-to-shallow direction differed by method of measurement. Meta-analysis, Level II.

Relationship between femoral tunnel location and graft bending angle in outside-in and transportal technique for ACL double bundle reconstruction in 3D-CT study.

In anterior cruciate ligament (ACL) reconstruction, sharp angulation of the graft at tunnel aperture increases local strain to the graft. The purpose of this study is to investigate the relationship between femoral tunnel location and femoral graft bending angle after ACL double bundle reconstruction (ACL-DBR) with two different drilling techniques. In ACL-DBR, femoral tunnel was created by two techniques; outside-in technique (26 patients, group A) and transportal technique (25 patients, group B). CT scan was taken at 1week postoperatively. The position of femoral tunnel exit on the lateral femoral cortex, and intra-articular femoral and tibial tunnel aperture of the anteromedial bundle (AMB) and postero-lateral bundle (PLB) was measured using a rectangular frame on three-dimensional CT images. Femoral graft bending angle was measured using two-dimensional CT images. Femoral tunnel exits of AMB and PLB in group A were significantly anterior and proximal than those in group B (p<0.05), while there was no significant difference in intra-articular femoral and tibial tunnel apertures between group A and B. A mean femoral graft bending angle of AMB was 80.3° in group A and 69.2 degrees in group B, respectively (p<0.05). A mean femoral graft bending angle of PLB was 66.3° in group A and 64.6° in group B, respectively. In both groups, a significant (p<0.05) correlation (r<-0.4) was observed between the position of the femoral tunnel exit (anterior-posterior ratio from femoral anterior border line) and the femoral graft bending angle in AMB. Since the femoral tunnel exit in outside-in technique was located more anterior and proximal, femoral graft bending angle of AMB in outside-in technique was greater than that in transportal technique. Anterior position of the femoral tunnel exit in AMB increased femoral graft bending angle in outside-in and transportal techniques.

Anatomic Single-bundle Anterior Cruciate Ligament Reconstruction Using the Flexible Drilling/Reaming system: A Preliminary Experience

Introduction: The purpose of anatomic anterior cruciate ligament (ACL) reconstruction is to restore the normal function of the ACL. Therefore, the ACL should be reconstructed at its original footprint. There are many different methods to create the femoral tunnel, including the transtibial, transportal, and outside-in techniques. Each method has different benefits and limitations. Thus, we used the flexible reamer system to perform the anatomic ACL reconstruction. Materials and methods: From May 2014 to Feb 2015, 26 patients in our hospital received single-bundle ACL reconstructions using the flexible reamer system. Twenty men and 6 women with a mean age of 30.6 years were included. The EndoButton was applied for femoral site fixation and tibial site was fixed with the PLLA-HA interference screw and one post screw. After the operation, the patients' knee joints were protected with the range of motion (ROM) brace at zero degree for 2 weeks. The range motion of the brace was subsequently adjusted to 60, 90, and 120 degrees at the 2nd, 4th, and 6th postoperative week, respectively. Results: No major complications, including wound infection, vascular or nerve injuries, were reported in these patients. However, breakage of the flexible guidewire occurred in one patient, which was smoothly resolved subsequently. The average femoral tunnel angle was measured. Post-operative three-dimensional computed tomography scans were also performed to check the femoral tunnel aperture location. Conclusion: Individualized anatomic ACL reconstruction is essential for ACL-deficient patients. With the flexible reaming system, the surgeon can easily create the femoral tunnel at the anatomic position. However, the surgeons should ensure the durability and sharpness of the guidewires and reamers by prior to the procedures.

An in Vivo 3D Computed Tomographic Analysis of Femoral Tunnel Geometry and Aperture Morphology Between Rigid and Flexible Systems in Double-Bundle Anterior Cruciate Ligament Reconstruction Using the Transportal Technique

The aim of this study was to compare femoral tunnel length, femoral graft-bending angle, posterior wall breakage, and femoral aperture morphologic characteristics between rigid and flexible systems after double-bundle (DB) anterior cruciate ligament (ACL) reconstruction using the transportal (TP) technique. We evaluated 3-dimensional computed tomography (3D-CT) results for 54 patients who underwent DB ACL reconstruction using the TP technique with either a flexible system (n= 27) or a rigid system (n= 27). The femoral tunnel length, femoral graft-bending angle, posterior wall breakage, femoral tunnel aperture height to width (H:W) ratio, aperture axis angle, and femoral tunnel position were assessed using OsiriX Imaging Software and Geomagic Qualify 2012 (Geomagic, Cary, NC). The mean anteromedial (AM) femoral tunnel length of the flexible group was significantly longer than that of the rigid group (P= .009). The mean femoral graft-bending angles in the flexible group were significantly less acute than those in the rigid group (AM, P < .001; posterolateral [PL], P= .003]. Posterior wall breakage was observed in both groups (P= 1.00). The mean H:W ratios in the rigid group were significantly larger (more elliptical) than those of the flexible group (AM, P < .001; PL, P= .006). The mean aperture axis angle of the PL femoral tunnel in the rigid group was more parallel to the femoral shaft axis than that in the flexible group (P < .001). There were no significant differences in femoral tunnel position between the 2 groups. The AM femoral tunnel length and the AM/PL femoral graft-bending angle of the flexible system were significantly longer and less acute than those of the rigid system. However, the aperture morphologic characteristics of the AM/PL femoral tunnel and the aperture axis angle of the PL femoral tunnel in the rigid system were significantly more elliptical and closer to parallel to the femoral shaft axis than those of the flexible system. Level III, retrospective comparative study.

Eccentric Graft Positioning Within the Femoral Tunnel Aperture in Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Using the Transportal and Outside-In Techniques

Background: Ellipticity of the femoral tunnel aperture, which is considered to better restore the native anterior cruciate ligament (ACL) footprint after ACL reconstruction, is different according to the femoral tunneling technique used. How much of the femoral tunnel aperture is filled with graft in different tunneling techniques has yet to be evaluated. Purpose: The aim of this study was to evaluate and compare the graft filling area and graft position within the femoral tunnel aperture in ACL reconstruction using the transportal (TP) and outside-in (OI) techniques. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 70 patients were randomized to undergo double-bundle ACL reconstruction using either the TP (n = 35) or OI (n = 35) technique. The aperture filling was evaluated by calculating the ratio of the cross-sectional area of the graft to that of the femoral tunnel, and the graft center position within the tunnel was assessed using immediate postoperative magnetic resonance imaging. Results: The cross-sectional area of the femoral anteromedial (AM) tunnel aperture in the TP group (605.5 ± 112.7 mm2) was larger than that in the OI group (537.9 ± 126.8 mm2). The cross-sectional area of the femoral posterolateral (PL) tunnel aperture in the TP group (369.9 ± 88.3 mm2) did not differ significantly from that of the OI group (387.9 ± 87.0 mm2). The grafts filled only 52.0% of the AM tunnel and 55.3% of the PL tunnel in the TP group, compared with 54.9% of the AM tunnel and 54.4% of the PL tunnel in the OI group, but there was no statistically significant difference (P > .05). The AM graft center was positioned 1.7 ± 0.6 mm from the center of the tunnel aperture in the TP group and 1.6 ± 0.5 mm in the OI group, and the PL graft center was positioned 1.4 ± 0.4 mm from the center in the TP group and 1.3 ± 0.4 mm in the OI group, with no significant intergroup differences (P = .406 and P = .629, respectively). In the OI group, the PL graft center was positioned more perpendicular to the Blumensaat line in relation to the tunnel aperture center (−10.8° ± 7.6°) compared with the TP group (−4.0° ± 11.8°) (P = .04). Conclusion: The grafts did not fill the tunnel aperture area in either group, and the centers of the grafts differed slightly from the centers of the tunnel apertures. The finding of eccentric graft positioning in the tunnel with condensation in a particular direction in each technique might suggest the necessity of an underreamed femoral tunnel for graft. In addition, it may be useful to standardize the starting position of the femoral tunnel according to anatomic landmarks.

Comparison of Clinical and Radiological Parameters with Two Different Surgical Methods for Anterior Cruciate Ligament Reconstruction

Objectives:We investigated the effects anatomic or nonanatomic femoral tunnel positions and tunnel fixation methods obtained using two different surgery methods on tunnel widening and clinical results in anterior cruciate ligament (ACL) reconstructions.Methods:Patients with isolated anterior cruciate ligament rupture are included to study who don’t have intra-and extra-articular additional pathology of the knee, without previously a history of operations of both knees. 2 groups were created. Group 1 Aperfix implant were used which can be able to perform non anatomical femoral tunnel and intra tunnel fixation with transtibial technique. In Group 2 Endobutton CL implant were used which can make fixation from outside the cortex with anatomic femoral tunnel in use of anteromedial portal techniques. 27 patients (average age 29,33, range 18 to 55 years) in group 1 and 27 patients (average age 27,51, range 16 to 45 years) in group 2 totally 54 patients were performed surgery. All patients were assessed using the IKDC (International knee documentation committee), Tegner Activity Scala and Lysholm II Functional Scores. Muscle strength measurements in both groups compared to intact knee was measured with an isokinetic dynamometer Biodex System 3 Pro. The location of the femoral tunnel aperture and tunnel widening were imaged with 3D reconstructive computed tomography. All measurements were performed using the same software application by the same radiologist.Results:The two groups were similar with respect to age and sex distribution, operated side, the size of the tunnel created, and follow-up period (p>0.05). After surgery in both groups, the clinical scores showed significant improvement compared to preoperative (p=0,0001). However, postoperative clinical outcomes in the two groups did not show a difference significantly (p>0,005). Isokinetic muscle strength study showed significant differences between the two groups (p=0,0001). Location of femoral tunnel aperture on the medial wall of the lateral femoral condyle showed a significant differences in the two groups (p=0,0001). The expansion of proximal and distal femoral tunnel in two groups showed significant differences (p=0,0001). There was relationship between distal femoral tunnel widening and location of femoral tunnel aperture.Conclusion:Although there is no statistically significant difference between the two groups clinically, difference noticed in terms of isokinetic muscle strength may be due to differences in the degree of shift as a result of multiple loading depending on the biomechanical properties of materials. We thought that the difference seen in the widening of tunnel in the proximal or distal may be due to, the technique of graft fixation, the distance between the fixation point and the joint, and to the location of the femoral tunnel aperture on medial wall of lateral condyle from anatomical or non anatomical region. There is no golden standard in neither surgical technique nor material of fixation. Proper theoretical knowledge and extensive clinical experience are important in the light of an accurate surgical technique applied. We thought that information we have reached in our study should be supported by biomechanical studies

The predictive effect of anatomic femoral and tibial graft tunnel placement in posterior cruciate ligament reconstruction on functional and radiological outcome.

Biomechanical reports have advocated anatomic graft tunnel placement for reconstruction of the posterior cruciate ligament (PCL) to restore knee joint stability and facilitate optimal functional outcome. However, in vivo investigations that correlate tunnel position to functional results are lacking so far. This study evaluates the anatomic accuracy of femoral and tibial tunnel apertures on postoperative computed tomography (CT) scans and compares these findings to subjective and objective clinical outcome parameters. After single-bundle PCL reconstruction, 29 patients were stratified into several subgroups according to the anatomic accuracy of femoral and tibial tunnel apertures measured on postoperative CT scans. A threshold value for the centres of the tunnel apertures was determined using a measurement grid system as a radiographic reference. To evaluate the functional and radiological results, visual analogue scale, International Knee Documentation Committee (IKDC), Tegner, Lysholm, Knee Injury and Osteoarthritis Outcome Score and osteoarthritis scores were obtained. Comparison between functional outcome and tunnel position yielded a statistically significant difference for subjective IKDC score and angle segment α and for objective stability and tunnel position P3 but no statistically significant difference with respect to intercondylar depth, intercondylar height and tibial tunnel position P2. No correlation was found between anatomic tunnel position and present or progressive osteoarthritis on follow-up. Of the patients, 72 % classified their result as excellent and good and 90 % would repeat surgical treatment. Despite a small sample size and subject to the threshold values we used, our data indicate a potentially minor effect of anatomic tunnel placement on midterm functional outcome following PCL reconstruction.

Creation of femoral tunnel by outside-in technique for ACL reconstruction: an analysis.

To study the outcome of ACL reconstruction by retrograde outside-in (OI) creation of femoral tunnel. ACL reconstruction was done in 41 cases by OI technique. The tip of 115° femoral guide was placed at posterior aspect of femoral foot print of ACL. Reaming was done from outside-in over guide pin. The length of femoral tunnel was obtained by measuring guide pin. The location of intra-articular femoral tunnel aperture and graft was recorded. Tibial tunnel was created with 50° guide placed at tibial foot print of ACL. Post-operative digital radiograph was taken. Antero-posterior view was used to calculate coronal inclination of femoral tunnel. On lateral view femoral tunnel location was marked in relation to the intersection of Blumensaat line and posterior femoral cortical line. Lysholm scoring and pivot shift test were performed at follow-up. Objective measurement of anterior tibial translation was done by rolimeter (aircast) at 1 year. The mean femoral tunnel length recorded was 39.5 mm (±3.4). There was no incidence of femoral tunnel blow out or graft impingement. All cases had femoral tunnel aperture location posterior to posterior femoral cortical line and inferior to Blumensaat line. The mean coronal angle of femoral tunnel was 30.39° (±4.6). The mean preoperative Lysholm score of 53.5 (±13) increased to 95.2 (±3.5) 1 year after surgery. All the patients had full range of motion. The pivot shift test was negative and instrumented measurement of anterior translation of tibia was near normal in all cases. OI technique of ACL reconstruction is a simple reproducible technique. The unconstrained placement and angling of femoral guide result in a femoral tunnel which is through footprint of ACL. The graft is placed very low, oblique and as posterior as possible on femoral side mimicking the native ACL. III.

Morphological changes in femoral tunnels after anatomic anterior cruciate ligament reconstruction.

Few studies investigated the enlargement inside the tunnel as well as the morphological change at the aperture after anterior cruciate ligament (ACL) reconstruction, whereas the tunnel enlargement has been well documented. The purposes were to evaluate the change in the cross-sectional area along the femoral tunnel and to morphologically clarify the enlargement at the femoral tunnel aperture after anatomic triple-bundle (ATB) ACL reconstruction. The study included 15 patients with unilateral ACL rupture. ATB ACL reconstruction was performed using semitendinosus tendon autografts. Three-dimensional computer models of the femur and bone tunnels were reconstructed from computed tomography images obtained 3 weeks and 1 year postoperatively. The cross-sectional area at the aperture as well as inside the tunnel was compared between the two periods. Likewise, the location of tunnel walls and center in the tunnel footprint were evaluated. The cross-sectional area enlarged by 22.7 % for anteromedial/intermediate graft (P = 0.002) and 28.6 % for posterolateral graft (P = 0.002) at the aperture, while decreased by 36.2 % at 10 mm from the aperture for anteromedial/intermediate graft (P = 0.004). Both the anterior and posterior walls shifted anteriorly, while the distal wall shifted distally in both tunnels. Consequently, the center in the footprint significantly shifted anteriorly (4.9-6.6 %) and distally (2.2-2.6 %) in both tunnels. The femoral tunnel enlargement occurred at the aperture after ATB ACL reconstruction, but did not occur in the middle of the femoral tunnel. The morphology at the aperture changed with time after surgery as the tunnel walls translated anteriorly and distally. Case series, Level IV.

Skeletal imaging following reconstruction of the posterior cruciate ligament: in vivo comparison of fluoroscopy, radiography, and computed tomography.

Intra- and postoperative validation of anatomic footprint replication in posterior cruciate ligament (PCL) reconstruction can be conducted using fluoroscopy, radiography, or computed tomography (CT) scans. However, effectiveness and exposure to radiation of these imaging modalities are unknown. The objective of this study was to evaluate the comparative effectiveness of fluoroscopy, radiography, and CT in detecting femoral and tibial tunnel positions following an all-inside reconstruction of the PCL ligament in vivo. The study design was a retrospective case series. Intraoperative fluoroscopic images, postoperative radiographs, and CT scans were obtained in 50 consecutive patients following single-bundle PCL reconstruction. The centers of the tibial and femoral tunnel apertures were identified and correlated to measurement grid systems. The results of fluoroscopic, radiographic, and CT measurements were compared to each other and accumulated radiation dosages were calculated. Comparing the imaging groups, no statistically significant difference could be detected for the reference of the femoral tunnel to the intercondylar depth and height, for the reference of the tibial tunnel to the mediolateral diameter of the tibial plateau and for the superoinferior distance of the tibial tunnel entry to the tibial plateau and to the former physis line. Effective doses resulting from fluoroscopic, radiographic, and CT exposure averaged 2.9mSv, standard deviation (±SD) 4.1mSv, to 1.3 ± 0.8mSv and to 3.6 ± 1.0mSv, respectively. Fluoroscopy, radiography, and CT yield approximately equal effectiveness in detecting parameters used for quality validation intra- and postoperatively. An accumulating exposure to radiation must be considered.

In vivo evaluation of femoral and tibial graft tunnel placement following all-inside arthroscopic tibial inlay reconstruction of the posterior cruciate ligament

The arthroscopic all-inside tibial inlay technique represents a novel procedure for posterior cruciate ligament (PCL) reconstruction. However, in vivo investigations that evaluate the accuracy of this technique regarding anatomic graft tunnel placement are few. The objective of this study was to analyse the femoral and tibial tunnel apertures using computed tomography (CT) and compare these findings to recommendations in the literature. CT scans were obtained in 45 patients following single-bundle PCL reconstruction. The centres of the tibial and femoral tunnel apertures were correlated to measurement grid systems used as a radiographic reference. The centre of the femoral tunnel aperture was located at 42.9% ± 9.4% of the total intercondylar depth and at 12.9% ± 7.2% of the total intercondylar height. The angle α for the femoral tunnel position was measured at 64.2° ± 10.0°. The centre of the tibial tunnel aperture was found at 51.8% ± 4.1% of the total mediolateral diameter of the tibial plateau. The superoinferior distance of the tibial tunnel aperture to the joint line was 9.6 mm ± 4.4 mm on frontal and 9.3 mm ± 3.4 mm on sagittal 3D-CT scans. The distance of the tibial tunnel aperture to the former physis line averaged to 0.8 mm ± 3.4 mm. Comparison to the corresponding reference values revealed no statistically significant difference. Arthroscopic tibial inlay reconstruction is an efficient procedure for precise replication of the anatomical footprint of the PCL. IV, prospective case series.

Is the native ACL insertion site "completely restored" using an individualized approach to single-bundle ACL-R?

The goal of individualized anatomic anterior cruciate ligament reconstruction (ACL-R) is to reproduce each patient's native insertion site as closely as possible. The amount of the native insertion site that is recreated by the tunnel aperture area is currently unknown, as are the implications of the degree of coverage. As such, the goals of this study are to determine whether individualized anatomic ACL-R techniques can maximally fill the native insertion site and to attempt to establish a crude measure to evaluate the percentage of reconstructed area as a first step towards elucidating the implications of complete footprint restoration. This is a prospective pilot study of 45 patients who underwent primary single-bundle anatomic ACL-R from May 2011 to April 2012. Length and width of the native insertion site were measured intraoperatively. Using published guidelines, reconstruction technique and graft choice were determined to maximize the percentage of reconstructed area. Native femoral and tibial insertion site area and femoral tunnel aperture area were calculated using the formula for area of an ellipse. On the tibial side, tunnel aperture area was calculated with respect to drill diameter and drill guide angle. Percentage of reconstructed area was calculated by dividing total tunnel aperture area by the native insertion site area. The mean areas for the native femoral and tibial insertion sites were 83±20 and 125±20mm(2), respectively. The mean tunnel aperture area for the femoral side was 65±17, and 86±17mm(2) for the tibial tunnel aperture area. On average, percentage of reconstructed area was 79±13% for the femoral side, and 70±12% for the tibial side. Anatomic ACL-R does not restore the native insertion site in its entirety. Percentage of reconstructed area serves as a rudimentary tool for evaluating the degree of native insertion site coverage using current individualized anatomic techniques and provides a starting point from which to evaluate the clinical significance of complete footprint restoration. IV.

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.

Eccentric Femoral Tunnel Widening in Anatomic Anterior Cruciate Ligament Reconstruction

The purpose of this study was to retrospectively evaluate femoral tunnel widening (TW) and migration of the femoral tunnel aperture after anatomic anterior cruciate ligament (ACL) reconstructions with hamstring grafts and bone-patellar tendon-bone (BPTB) grafts. Of the 105 consecutive patients who underwent ACL reconstruction, the 52 patients who underwent isolated ACL reconstruction and in whom tunnel measurement could be obtained by computed tomography were included in this study. In 26 patients, double-bundle reconstruction (DBR) of the ACL using hamstring tendons was performed. These patients were compared with 26 patients in whom rectangular tunnel ACL reconstruction using BPTB grafts (BPTBR) was performed. Femoral tunnel aperture positioning and TW were investigated postoperatively using 3-dimensional computed tomographic images, which were performed a week and a year after surgery in all patients. In DBR, the average diameter of the anteromedial (AM) femoral tunnel increased by 34.0% in the horizontal direction and 28.2% in the vertical direction, whereas that of the posterolateral (PL) femoral tunnel increased by 58.2% and 73.4%, respectively, at 1 year after surgery compared with 1 week after surgery. The percentage TW value of the PL tunnel was significantly greater than that of the AM tunnel. In BPTBR, the average diameter increased by 22.0% and 17.1%, respectively. The percentage TW value of the PL tunnel in DBR was significantly greater than that of the femoral tunnel in BPTBR. Each tunnel aperture migrated distally ("shallow") in the horizontal direction and high in the vertical direction. AM and PL tunnel apertures in DBR migrated in the vertical direction significantly more than they did in BPTBR. No significant differences between the 2 groups were found in clinical outcomes. The femoral PL tunnel aperture in DBR showed significantly more widening than did the AM tunnel aperture in DBR and the femoral tunnel aperture in BPTBR. Also, greater migration of the femoral tunnel aperture in the vertical direction because of TW was observed in DBR than in BPTBR. Level IV, therapeutic case series.

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.

A modified quadrant method for describing the femoral tunnel aperture positions in ACL reconstruction using two-view plain radiographs

A modified quadrant method was developed for description of femoral tunnel aperture positions on the sagittal plane after double-bundle anterior cruciate ligament (ACL) reconstruction, which can be measured by using two-view radiographs. The purpose of the study is to provide a new measurement method and to evaluate the reproducibility and accuracy of the method. Forty-one patients who had undergone a double-bundle ACL reconstruction were investigated. Two-view plain radiographs, a 45-degree-flexion posterior-anterior standing (Rosenberg) and a lateral view, were taken at 1year postoperatively, and the femoral tunnel positions were measured. Intra- and inter-observer reproducibility was calculated by means of intra-class correlation coefficient (ICC). Also, the accuracy of the method was evaluated by comparing the measurement from three-dimensional computed tomography (3D-CT). Intra-observer reproducibility was excellent (ICC>0.9). Inter-observer reproducibility of antero-medial (AM) tunnel position was almost perfect (ICC>0.8) and that of postero-lateral (PL) tunnel was substantial (ICC>0.7). The accuracy of the method was assessed by comparing the measurement from 3D-CT and was found to be almost perfect (ICC>0.8). With the modified quadrant method, the average height of AM and PL tunnels were 17.8 and 44.4%, respectively, and the depth of AM and PL tunnels were 25.5 and 36.7%, respectively. A modified quadrant method was found to have acceptable reproducibility and accuracy. The method is useful for describing the femoral tunnel aperture positions in ACL reconstruction because of its easiness and simplicity. By using this method, it is possible to analyse the femoral tunnel position even in the cases without CT analysis. IV.

Comparison of tendon–bone healing between autografts and allografts after anterior cruciate ligament reconstruction using magnetic resonance imaging

The purpose of the study is to compare tendon-bone healing between autograft tendons and allograft tendons after anterior cruciate ligament (ACL) reconstruction using 3.0T magnetic resonance imaging. A total of 36 participants (18 with autograft and 18 with allograft reconstruction) underwent MRI scans at least 2years after the ACL reconstruction operation. Oblique axial images were obtained on three-dimensional dual-echo steady-state images and imported into solid modelling software for three-dimensional model reconstruction of the bone tunnel. The graft signal intensity in the tunnel, tendon-bone interface, tunnel morphology, and tunnel area was analysed using the Siemens software packages to determine the tendon-bone healing between the groups. For the tunnel morphology, both groups exhibited bone tunnel enlargement either at the femoral or tibial tunnel aperture. For the tendon-bone interface, one patient in the autograft group and two patients in the allograft group exhibited a significant fibrous scar tissue bands at the tendon-bone interface. The graft signal/noise quotient values of the allograft group were higher than the autograft group. However, there was no significant difference in the tunnel area between the allograft group and the autograft group. Although the autograft tendons exhibited a better remodelling effect than did the allograft tendons in the bone tunnel, there was no significant difference in the tendon-bone healing between the autograft tendons and the allograft tendons postoperatively. These findings indicate that the biomechanical effect of graft motion may play a significant role in the tunnel aperture. III.

Clinical outcome of anatomic double-bundle ACL reconstruction and 3D CT model-based validation of femoral socket aperture position

The purpose of this study was to evaluate the clinical results of anatomic double-bundle (DB) anterior cruciate ligament (ACL) reconstruction in which anatomic position of femoral socket apertures was validated using three-dimensional (3D) computed tomography (CT) modelling. Anatomic DB ACL reconstructions with hamstring autografts were performed in 34 patients. Two femoral sockets were created through a far anteromedial (AM) portal behind the lateral intercondylar ridge with the assistance of intraoperative 3D fluoroscopic navigation. Femoral tunnel aperture positioning was investigated postoperatively using 3D CT images in all patients. Clinical results were also evaluated subjectively and objectively at least up to 2 years. Measurement of the AM and the posterolateral (PL) femoral socket locations on the 3D CT images using the quadrant method showed that the centre of the AM socket aperture was located at a depth of 21.0 ± 4.1% and a height of 30.5 ± 9.3% and that of the PL socket aperture was located at a depth of 31.3 ± 5.8% and a height of 57.2 ± 7.7%. The femoral socket locations were considered as anatomic in accordance with previous cadaveric studies examining the positions of ACL femoral insertion site. Subjectively, the mean Lysholm score was 96.9 ± 4.0 points. According to IKDC final objective scores, 26 knees (76%) were objectively graded as normal, 8 (24%) as nearly normal, and 0 (0%) as abnormal or severely abnormal. Postoperative side-to-side anterior translation measured with a KT-2000 arthrometer averaged 0.7 ± 1.2 mm. DB ACL reconstructions in which femoral socket apertures were validated anatomically using 3D CT provided satisfactory short-term results. Case series, Level IV.