Femoral Tunnel Length Research Articles

Contact area between femoral tunnel and interference screw in anatomic rectangular tunnel ACL reconstruction: a comparison of outside-in and trans-portal inside-out techniques.

The purpose of this study was to compare the femoral tunnel length, the femoral graft bending angle at the femoral tunnel aperture, and the contact area between the femoral tunnel wall and an interference screw used for fixation in anatomic rectangular tunnel anterior cruciate ligament (ACL) reconstruction (ART ACLR). The study included 149 patients with primary ACL injury who underwent ART ACLR. Preoperatively, flexion angle of the index knee was checked under general anaesthesia. Those of less than 130° of passive flexion were assigned to the outside-in (OI) technique (78 patients), while the others to the trans-portal inside-out (TP) technique (71 patients). The patients underwent computed tomography with multiplanar reconstruction at 3-5weeks post-operatively. Femoral tunnel length, graft bending angle, and contact ratio between the IFS and femoral tunnel were assessed. P<0.05 was considered statistically significant. The femoral tunnel length in the OI technique was significantly longer than that in the TP technique (P<0.001). The femoral graft bending angle in the OI technique was significantly more acute than that in the TP technique (P<0.001). The contact ratio in the OI technique was significantly larger than that in the TP technique at every point in the femoral tunnel (P<0.001). The OI technique resulted in a more acute femoral graft bending angle, longer mean femoral tunnel length, and larger contact ratio than the TP technique after ART ACLR. Retrospective comparative study, Level III.

Transtibial Versus Anteromedial Portal ACL Reconstruction: Is a Hybrid Approach the Best?

Background:Improved biomechanical and clinical outcomes are seen when the femoral tunnels of the anterior cruciate ligament (ACL) are placed in the center of the femoral insertion. The transtibial (TT) technique has been shown to be less capable of this than an anteromedial (AM) portal approach but is more familiar to surgeons and less technically challenging. A hybrid transtibial (HTT) technique using medial portal guidance of a transtibial guide wire without knee hyperflexion may offer anatomic tunnel placement while maintaining the relative ease of a TT technique.Purpose:To evaluate the anatomic and biomechanical performance of the HTT technique compared with TT and AM approaches.Study Design:Controlled laboratory study.Methods:Thirty-six paired, fresh-frozen human knees were used. Twenty-four knees (12 pairs) underwent all 3 techniques (TT, AM, HTT) for femoral tunnel placement, with direct measurement of femoral insertional overlap and femoral tunnel length. The remaining 12 knees (6 pairs) underwent completed reconstructions to evaluate graft anisometry and tunnel orientation, with each technique performed in 4 specimens and tested using motion sensors with a quad-load induced model. Graft length changes and graft/femoral tunnel angle were measured at varying degrees of flexion.Results:Percentage overlap of the femoral insertion averaged 37.0% ± 28.6% for TT, 93.9% ± 5.6% for HTT, and 79.7% ± 7.7% for AM, with HTT significantly greater than both TT (P = .007) and AM (P = .001) approaches. Graft length change during knee flexion (anisometry) was 30.1% for HTT, 12.8% for AM, and 8.5% for TT. When compared with the TT approach, HTT constructs exhibited comparable graft–femoral tunnel angulation (TT, 150° ± 3° vs HTT, 142° ± 2.3°; P < .001) and length (TT, 42.6 ± 2.8 mm vs HTT, 38.5 ± 2.0 mm; P = .12), while AM portal tunnels were significantly shorter (31.6 ± 1.6 mm; P = .001) and more angulated (121° ± 6.5°; P < .001).Conclusion:The HTT technique avoids hyperflexion and maintains femoral tunnel orientation and length, similar to the TT technique, but simultaneously achieves anatomic graft positioning.Clinical Relevance:The HTT technique offers an anatomic alternative to an AM portal approach while maintaining the technical advantages of a traditional TT reconstruction.

Influence of the different anteromedial portal on femoral tunnel orientation during anatomic ACL reconstruction

ObjectiveThe purpose of this study was to evaluate the effect of femoral tunnel orientation, drilled through the accessory anteromedial (AAM) portal or the high AM portal in anatomic anterior cruciate ligament (ACL) reconstruction. MethodsIn 16 cadaver knees, using o'clock method, centers of the ACL femoral footprint were drilled with an 8-mm reamer via an AAM portal (eight knees) or a high AM portal (eight knees). Computed tomography (CT) scans were taken of each knee. Three-dimensional (3D) models were constructed to identify the femoral tunnel orientation and to create femoral tunnel virtual cylinders for measuring tunnel angles and length. ResultsIn two of the 16 specimens, we observed a posterior femoral cortex blowout (PFCB) when drilling through a high AM portal. When drilled through the high AM portal, the femoral tunnel length was significantly shorter than when using an AAM portal (30.3 ± 3.8 mm and 38.2 ± 3.1 mm, p < 0.001). The femoral tunnel length was significantly shorter in the group with PFCB compared to the group with no PFCB (25.9 ± 0.6 mm and 35.5 ± 4.5 mm, p = 0.011). The axial obliquity of the high AM portal was significantly higher than that of the AAM portal (52.2 ± 5.9° and 43.0 ± 2.3°, p = 0.003). ConclusionsIn anatomic ACL reconstruction, a mal-positioned AM portal can cause abnormal tunnel orientation, which may lead to mechanical failure during ACL reconstruction. Therefore, it is important to select accurate AM portal positioning, and possibly using an AAM portal by measuring an accurate position when drilling a femoral tunnel in anatomic ACL reconstruction.

Sagittal femoral condyle morphology correlates with femoral tunnel length in anatomical single bundle ACL reconstruction.

The purpose of this study was to reveal the correlation between femoral tunnel length and the morphology of the femoral intercondylar notch in anatomical single bundle anterior cruciate ligament (ACL) reconstruction using three-dimensional computed tomography (3D-CT). Thirty subjects undergoing anatomical single bundle ACL reconstruction were included in this study (23 female, 7 male: average age 45.5 ± 16.7). In the anatomical single bundle ACL reconstruction, the femoral and tibial tunnels were created close to the antero-medial bundle insertion site with trans-portal technique. Using post-operative three-dimensional computed tomography (3D-CT), accurate axial and lateral views of the femoral condyle were evaluated. The correlation of femoral tunnel length, which was measured intra-operatively, with the transepicondylar length (TEL), notch width index, notch outlet length, the notch area (axial), length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch was statistically analyzed. Tunnel placement was also evaluated using a Quadrant method. The average femoral tunnel length was 35.4 ± 4.4mm. The average TEL, NWI, notch outlet length, and the axial notch area, were 76.9 ± 5.1mm, 29.1 ± 3.8%, 19.5 ± 3.9mm, and 257.4 ± 77.4mm2, respectively. The length of Blumensaat's line and the height and area of the lateral wall of the femoral intercondylar notch were 33.8 ± 3.2mm, 22.8 ± 2.3mm, and 738.7 ± 129mm2, respectively. The length of Blumensaat's line, the height, and the area of the lateral wall of the femoral intercondylar notch were significantly correlated with femoral tunnel length. Femoral tunnel placement was 23.4 ± 4.5% in a shallow-deep direction and 35.4 ± 8.8% in a high-low direction. The length of Blumensaat's line, height, and area of the lateral wall of the femoral intercondylar notch are correlated with femoral tunnel length in anatomical single bundle ACL reconstruction. For clinical relevance, these parameters are useful in predicting the length of the femoral tunnel in anatomical single bundle ACL reconstruction for the prevention of extremely short femoral tunnel creation. Case controlled study, Level III.

Three-Dimensional Reconstruction Computed Tomography Evaluation of the Tunnel Location and Angle in Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction: A Comparison of the Anteromedial Portal and Outside-in Techniques

PurposeThe purpose of this study was to compare the geometry and position of the femoral tunnel between the anteromedial portal (AMP) and outside-in (OI) techniques after anatomic single-bundle anterior cruciate ligament (ACL) reconstruction.Materials and MethodsWe evaluated 82 patients undergoing single-bundle ACL reconstruction with hamstring autografts using either the AMP (n=40) or OI (n=42) technique. The locations of the tunnel apertures were assessed by postoperative 3-dimensional computed tomography imaging. The femoral graft bending angle, femoral tunnel aperture shape, femoral tunnel length, and posterior wall breakage were also measured.ResultsThe mean femoral tunnel position parallel to the Blumensaat line was more caudally positioned in the AMP group than in the OI group (p=0.025) The mean femoral graft angle in the OI group (99.6°±7.1°) was significantly more acute than that of the AMP group (108.9°±10.2°, p<0.001). The mean height/width ratio of the AMP group (1.21±0.20) was significantly more ellipsoidal than that of the OI group (1.07±0.09, p<0.001).ConclusionsThe mean femoral tunnel position was significantly shallower in the AMP technique than in the OI technique. The OI technique might be more disadvantageous than the AMP technique in terms of the more acute bending angle.

Three-Dimensional Reconstruction Computed Tomography Evaluation of the Tunnel Location and Angle during Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction

Purpose:Tibial tunnel-independent drilling has attracted increased interest in recent years for anatomic anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to compare the geometry and position of the femoral tunnel between the anteromedial portal (AMP) and outside-in (OI) techniques after anatomic single-bundle ACL reconstruction.Methods:We prospectively evaluated 82 patients undergoing single-bundle ACL reconstruction with hamstring tendon autografts using either the AMP (n=40) or OI (n=42) technique. The locations of the tibial and femoral tunnel apertures were assessed by immediate postoperative 3-dimensional computed tomography (3D CT) imaging with OsiriX imaging software. The femoral graft bending angle, femoral tunnel aperture shape (height/width ratio), femoral tunnel length, and posterior wall breakage were also measured.Results:The two techniques did not differ significantly in the femoral tunnel position perpendicular to the Blumensaat line. However, the mean femoral tunnel position parallel to the Blumensaat line was more caudally positioned in the AMP group than in the OI group (P=0.025) The two groups did not differ significantly in tibial tunnel position. The mean femoral tunnel length did not differ between the AMP (36.1±0.33 mm) and OI groups (35.6±0.37 mm; P=0.548) The mean femoral graft angle in the OI group (99.6°±7.1°) was significantly more acute than that of the AMP group (108.9°±10.2°) (p < 0.0001). The mean height/width ratio of the AMP group (1.21±0.20) was significantly more ellipsoidal than that of the OI group (1.07±0.09) (p < 0.0001). Posterior wall breakage was detected in 3 cases (7.5%), all in the AMP group.Conclusions:After single-bundle anatomic ACL reconstruction, 3D CT showed a significantly shallower femoral tunnel in the AMP group than in the OI group. The AMP group had a more ellipsoidal femoral tunnel with a risk of posterior wall breakage than the OI group. The OI group showed a more acute bending angle of the femoral tunnel than the AMP group.The femoral graft bending angle planeThe femoral graft bending angle plane, in which the centers of the extra- and intra-articular apertures of the femoral tunnel and the center of the intra-articular aperture of the tibial tunnel were viewed together, was selected to measure the femoral graft bending angle.three-dimensional computed tomographyOn the lateral femoral side of three-dimensional computed tomography, the location of the transtibial and tibial independent femoral tunnel are shown. The location of the tunnels was quantified and presented as the percentage distance from the deepest subchondral contour and the intercondylar notch roof to the center of the tunnel

Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction Using the Modified Transtibial Technique

We present a technique for anterior cruciate ligament (ACL) reconstruction using hamstring tendon autograft with a modified transtibial technique. Our modified transtibial technique has the advantages of the conventional transtibial technique that is familiar to surgeons and that allows the press-fit fixing and enables us to make a relatively long femoral tunnel. To make the femoral tunnel at the anatomic position, the triangular, funnel-shaped bony trough was made to slip the eccentrically positioned guide pin into the anticipated anatomic center with a free-hand technique after marking the anatomic ACL footprint using a microfracture awl through the anteromedial portal. Gradual femoral reaming was performed with knee angle changes, which reduces the chances of posterior wall blowout, increases the femoral tunnel length, and avoids breakage of guide pin at the bending point. Our modified transtibial technique is anticipated to provide a more anatomic placement of the femoral tunnel during ACL reconstruction than the previous traditional transtibial techniques.

Optimization of Anteromedial Portal Femoral Tunnel Drilling With Flexible and Straight Reamers in Anterior Cruciate Ligament Reconstruction: A Cadaveric 3-Dimensional Computed Tomography Analysis

To use 3-dimensional custom CAD technology to evaluate how knee flexion angle affects femoral tunnel length and distance to the posterior wall when using curved and straight guides for drilling through the anteromedial portal (AMP). Six cadaveric knees were placed in an external fixator at various degrees of flexion (90°, 110°, 125°, and maximum 135° to 140°). Computed tomography scans were obtained at all flexion points for 3-dimensional point-cloud models. Using custom CAD software, surgical guides through the AMP were replicated along with virtual tunnels at each flexion angle. Distance from the posterior cortex and tunnel dimensions were collected after 8-mm and 10-mm tunnel creation. At 90° of flexion, the average tunnel length down the posterior aspect of 8-mm tunnel was 25.0mm (95% confidence interval [CI] 16.2-33.8) and 12.0mm (95% CI 7.3-16.7) for curved and straight guides, respectively; 31.0mm (95% CI 26.8-35.2) and 28.6mm (95% CI 24.8-32.4) at 110°; 33.8mm (95% CI 30.1-37.5) and 31.1mm (95% CI 26.8-35.4) at 125°; and 35.0mm (95% CI 34.1-35.9) and 35.5mm (95% CI 34.2-36.8) with maximal flexion. Values between curved and straight guides are significantly different (P < .001), with straight guides breaching the posterior wall at 90° and 110° of flexion in some specimens. The average distance to the posterior wall cortex was 0.9mm (95% CI-1.5 to 3.3) and-0.6mm (95% CI-2.3 to 1.1) for curved and straight guides, respectively, at 90° of flexion (P= .014); 2.3mm (95% CI-0.2 to 4.8) and-0.1mm (95% CI-2.4 to 2.2) at 110° (P= .001); 4.4mm (95% CI 2.8-6.0) and 3.9mm (95% CI 1.9-5.9) at 125° (P= .299); and 6.7mm (95% CI 6.2-7.2) and 8.3mm (95% CI 6.1-10.5) at maximal flexion (P= .184). Posterior wall blowout was noted when using 10-mm straight guides at both 90° (2 specimens) and 110° (3 specimens). Using 10-mm curved guides posterior blowout was noted in 1 specimen at 90°. Maximum footprint coverage occurred at 110° for straight guides and 90° for curved guides. When using the AMP, flexible guides and reamers result in a greater distance of the tunnel to the femoral cortex while preserving adequate tunnel length at lower knee flexion angles. To create long femoral tunnels without breaching the posterior cortex, the knee should be flexed to at least 110° for curved reamers and 125° for straight. Femoral tunnel drilling through the AMP using curved and straight reamers requires different degrees of knee flexion to achieve optimal tunnel dimensions.

Is there a difference between the flexible and rigid reamer in femoral tunnel length in ACL reconstruction in anteromedial portal

Background: Anterior cruciate ligament (ACL) reconstruction was functionally done on trans-tibial section and was creating vertical long tunnel. Nowadays, it is done by modified trans-tibial and anterior-medial portal which creates short tunnel compared to trans-tibial approach. Objective: To compare femoral tunnel length using a flexible versus rigid reamer in ACL antero-medial portal reconstruction surgery. Materials and Methods: Retrospective medical record analysis of all ACL reconstruction surgeries performed between February and December 2014 among 3 surgeons in security force hospital in Riyadh was done. In all of these procedures, the femoral tunnel length was measured with digital calipers from 20 to 48 mm and was reported in mm. Result: A total of 309 ACL reconstructions were done, 151 (18.9%) using a flexible reamer and 158 (51.1%) with a rigid reamer. The overall mean tunnel length was 38.6 ± 5.2 mm. The mean tunnel length in cases that used the flexible reamer was 39.0 ± 4.9 mm, and the mean tunnel length in cases that used the rigid reamer was 38.1 ± 5.4 mm. The mean difference in the tunnel length between flexible and rigid reamer was 0.88 mm. There was no statistical difference between the mean tunnel lengths between flexible and rigid reamers. There were no significant differences in the tunnel length performed by 3 different surgeons. Conclusion: The femoral tunnel lengths were not significantly different with the use of a flexible or a straight reamer.

Correlation of femoral tunnel length with body height, limb length, and thigh length in Indian patients undergoing anterior cruciate ligament reconstruction.

To measure the femoral tunnel length created through a far medial portal and determine its correlation with body height, limb length, and thigh length in 404 Indian patients undergoing anterior cruciate ligament (ACL) reconstruction. 364 male and 40 female Indian patients aged 18 to 51 (mean, 26.8) years underwent ACL reconstruction by a single surgeon using the hamstrings tendon autograft. Their body height, limb length, and thigh length were measured by a single assessor, as was the femoral tunnel length. The mean femoral tunnel length was 34.5 mm. It was <30 mm in 28 patients and <25 mm in 2 patients. The correlation coefficients of the femoral tunnel length with body height, limb length, and thigh length were 0.485 (p<0.0001), 0.426 (p<0.0001), and 0.304 (p<0.0001). No patient had posterior wall blowout fracture. The femoral tunnel length positively correlated with body height, limb length, and thigh length in 404 Indian patients.

Intégration dans le tunnel fémoral du greffon dans les reconstructions du LCA : voie transportale versus technique outside-in

Purpose Although the independent drilling techniques using transportal portal or outside-in approaches in ACL reconstruction have some advantages over the trans-tibial technique in placing the anatomical femoral tunnel, these techniques may make an acute graft-bending angle at the femoral tunnel entry or result in a short femoral tunnel length. However, there have been no reports on whether an acute graft-bending angle of an independent drilling technique might result in poor graft healing or negatively affecting clinical outcomes. The purpose of this study was to compare femoral tunnel geometry including tunnel position, length, and graft bending angle between the transportal and the outside-in techniques in ACL reconstruction and discover whether such differences in tunnel geometry could influence graft healing or clinical outcomes. Methods Sixty patients with anatomical single-bundle ACL reconstruction performed with use of either the transportal technique (32 patients) or the outside-in technique (28 patients) were included for this study. The femoral tunnel location, length and graft-bending angle at the femoral tunnel were analyzed on the 3D CT knee model, and we compared the location and length of the femoral tunnel, and graft-bending angle between the two techniques. Each group underwent MRI scans at least 1 year (range of 1–2 years) following the ACL reconstruction. We confirmed that all patients showed an intact ACL graft on the MRI images. On the oblique axial image taken after the ACL reconstruction, to determine graft healing at the femoral and tibial tunnels, and the intra-articular portion, the graft signal intensity ratio was calculated by dividing signal intensity (SI) of the reconstructed ACL by that of the posterior cruciate ligament (PCL) in the region-of-interest (ROI). We also compared the clinical outcomes in terms of Tegner activity scores, the International Knee Documentation Committee (IKDC) scores and Lachman and pivot-shift test results. Results While the location of femoral tunnel was similar in both groups, the femoral tunnel length was a little bit longer in the outside-in technique (37 vs. 32 mm, P = 0.07). Meanwhile, the outside-in technique showed a more significant acute graft tunnel angle than the transportal technique (100 vs. 113, P = 0.04). However, the signal intensity ratios of the grafts (compared with SI of PCL) were similar in femoral tunnel, tibial tunnel or intrarticular portions. Moreover, there were no significant statistical differences between the two groups in terms of IKDC scores (86.1 vs. 91.0, P = 0.32) and Tegner activity scores (6.5 vs. 6.8, P = 0.79). We also could not find any significant differences in the results of Lachman and pivot-shift tests. Conclusions Even though the outside-in technique in ACL reconstruction created a more acute femoral graft bending angle and a longer femoral tunnel length than the transportal technique, these had no negative effects in graft healing. In addition, the transportal and outside-in techniques in ACL reconstruction showed similar femoral tunnel positions, and no significant differences in clinical outcome. Therefore, the outside-in ACL reconstruction can be considered as the more effective method for surgeons to overcome the weakness of the traditional transportal technique.

Clinical advantages of image-free navigation system using surface-based registration in anatomical anterior cruciate ligament reconstruction.

To evaluate the clinical advantages of a navigation system developed with an emphasis on attaining an appropriate femoral tunnel length and posterior wall margin with no posterior wall blowout, as well as having accurate tunnel positioning, in anatomical anterior cruciate ligament reconstruction (ACLR). Ten freshly frozen human knees were transected at mid-femur and mid-tibia. Each knee specimen underwent arthroscopic single-bundle anterior cruciate ligament reconstruction using the outside-in technique, with two knees by manual ACLR (control group) and another eight knees by only the navigational ACLR without arthroscopic assistance (experimental group). The position/orientation information of tunnel entry point, tunnel length, and posterior wall distance of pre-, intra-, and postoperative tunnel were recorded, and the reliability and errors among them were evaluated. From comparison of the 3D models for preoperative planning and postoperative reconstruction, the mean differences for navigational femoral tunnelling and arthroscopic-assisted femoral tunnelling were recorded, respectively: (1) tunnel entry position, 1.4mm (SD 0.3) versus 4.9mm; (2) tunnel length, 0.7mm (SD 0.2), similar to 0.6mm in arthroscopic-assisted femoral tunnelling, and (3) posterior wall distance, 0.5mm (SD 0.2), much smaller than 4.7mm for arthroscopic-assisted femoral tunnelling. The intraclass correlation coefficients, calculated to determine the accuracy and reliability of navigational femoral tunnelling, showed excellent internal consistency that ranged from 0.965 to 0.989 for tunnel length and from 0.810 to 0.953 for posterior wall distance. Navigation systems with enhancement of the registration accuracy by the developed system are feasible in anatomical ACLR, in reducing surgical failures such as short tunnel length or posterior wall breakage of distal femur. The present study revealed that computer navigation could aid in avoiding major mistakes in exact positioning and posterior wall blowout and help in attaining appropriate length for femoral tunnelling in anatomical ACLR.

Transtibial Versus Anteromedial Portal ACL Reconstruction

Objectives:A number of studies suggest improved biomechanical and clinical results when ACL grafts are placed anatomically. Worldwide, the most common transtibial (TT) technique has been shown less anatomic than an anteromedial portal (AM) technique, though is much more familiar and less technically challenging. A hybrid transtibial approach (HTT) - using AM portal guidance of a flexible transtibial guide wire without knee hyperflexion - may offer anatomic graft placement while maintaining the relative ease of a transtibial technique. Our objective is to evaluate the anatomic and biomechanical performance of HTT, when compared to TT and AM approaches.Methods:A total of 36 paired, fresh-frozen human knees were used. 24 knees (12 pairs) - each using a standard tibial tunnel - underwent all three techniques (TT, AM, HTT) for femoral tunnel placement, with direct measurement of femoral insertional overlap and femoral tunnel length for each technique. The remaining 12 knees (6 pairs) were used to evaluate graft kinematics and tunnel orientation. Among these knees, 3 size-matched groups (four specimens each) were assigned to each of TT, AM and HTT techniques. Specimens were tested in quad-load induced extension from 90o to 10o of flexion with a distal weight used to simulate half-shank, ankle and foot passive load. Bony kinematics were assessed using a trakSTAR motion tracking system with three sensors installed in each femur and tibia. After femoral tunnel preparation, two sensors were installed in each tunnel to relate tunnel orientation and tunnel inlet location within the joint to the sensors used for motion tracking for the femur and tibia of each specimen. Bone-patellar-bone autografts were harvested from each specimen and used for the assigned reconstructive technique. Analysis included determination of ACL graft length changes, ACL-to-femoral tunnel angle and ACL-to-tibial tunnel angle at five flex/ext angles. Data was analyzed for three flex/ext tests on each specimen.Results:Femoral tunnel length averaged 42.6 mm ±2.8 mm for TT, 38.5 ±2.0 mm for HTT and 31.6 ±1.6 mm for AM, with HTT tunnels being comparable to TT (p=0.12) but significantly longer than AM (p=0.0005). Percentage insertional overlap of the femoral tunnel aperture averaged 37.0% ±28.6% for TT, 93.9% ±5.6% for HTT, and 79.7% ±7.7% for AM, with HTT overlap significantly greater than both TT (p=0.007) and AM (p=0.001). Mean ACL percent increase in length at 10o of flexion was significantly greater in HTT constructs as compared with TT constructs (30.1% vs 8.5%). HTT constructs also exhibited a significantly lower mean ACL-to-femoral tunnel angle vs TT constructs at 10o flexion (150.6o vs 160.8o). AM constructs demonstrated significantly lower mean ACL-to-femoral tunnel angles vs TT constructs at 30o, 50o and 70o of flexion. All other comparisons between the three construct types at the reported flexion angles were statistically similar.Conclusion:Our findings suggest highly anatomic femoral tunnel apertures are achieved with this hybrid technique, yet with the advantage of long femoral tunnels and minimal tunnel angulation comparable to a traditional transtibial technique. Further, grafts placed with this technique demonstrated more normal, anisometric behavior. The HTT technique may offer a more anatomic alternative to an AM portal approach, while maintaining the technical ease and familiarity of a traditional transtibial technique.

Overestimation of femoral tunnel length during anterior cruciate ligament reconstruction using the retrograde outside-in drilling technique.

When the femoral tunnel socket is reamed in an oblique direction from the wall of inter-condylar notch in anterior cruciate ligament (ACL) reconstruction, the tunnel length can be shorter at the periphery than at the centre. Because surgeons can manipulate the direction of tunnel in the outside-in femoral tunnel drilling technique, this length mismatch would vary depending on the direction of the tunnel. The purpose of this study was to investigate this length mismatch when reamed in various directions. In total of thirteen points were defined as femoral drilling entry points on concentric lines with 0, 1, 2, and 3cm radius from the lateral epicondyle of a three-dimensional bone model from 40 subjects. Femoral tunnel drilling was simulated on the models by connecting the centre of the ACL footprint with each defined point on the lateral femoral surface. The mismatch length was measured between the centre and the shortest peripheral side of the tunnel socket. When the distance between the drilling entry point on the lateral femoral surface and the lateral epicondyle was increased to anterior proximal direction, there was a significant increase in the mismatch length. The mismatch length became more than 2mm when the entry point was located more than 2cm away from the lateral epicondyle. When the drilling entry point is set far away from the lateral epicondyle, a significant increase was observed in tunnel length mismatch between the centre of the tunnel and its shortest peripheral side. Because the tunnel length is measured with a guide pin introduced at the centre of the tunnel before reaming in retrograde outside-in technique, this length mismatch could cause an overestimation of the tunnel length. Surgeons should recognise this mismatch when preparing the length of graft and socket to optimise the graft insertion length into the socket.

Anterior cruciate ligament reconstruction with 70° arthroscope and flexible reamers – Early operative experience

Anatomical graft position for anterior cruciate ligament (ACL) reconstruction is desirable. However, visualisation and positioning are challenges with the standard technique. It is known that graft integration can be improved by maximising femoral tunnel length and graft failure reduced by limiting bending angle. We planned to evaluate the use of new techniques whilst monitoring femoral tunnel length and angle.A 70° arthroscope, through the anterolateral portal, provided improved footprint visualisation without the need to switch to a medial portal. A flexible reamer system created the femoral tunnel without hyperflexion of the knee. Femoral tunnel length was measured intra-operatively using the graduations on the reamer, and femoral tunnel angle was assessed on the post-operative radiograph (using a digital measuring tool).In a single-surgeon, consecutive series, 55 patients were treated. When compared to the surgeon's 65 previous cases, femoral tunnel length increased significantly by 3.11mm (40.1 (±3.49)° vs. 36.9 (±3.87)°; p<0.05) with no significant change in femoral tunnel angle (37.8 (±4.97)mm vs. 39.6 (±5.11)mm; p=0.075).We discuss this technique with reference to potential advantages and disadvantages of this technology.

Avoidance of Reamer Breakage During ACL Reconstruction With Flexible Reamer System: Letter to the Editor.

Dear Editor: I read with great attentiveness the article titled “Anterior Cruciate Ligament Reconstruction Using a Flexible Reamer System: Technique and Pitfalls” by Fitzgerald et al,1 published in July 2015. It is a perfectly timed article, as surgeons are actually looking to PubMed to know the tips, tricks, and results of the “flexible drilling system for anatomical ACL reconstruction” owing to recent promotion of the Clancy System by Smith & Nephew and the VersiTomic System by Stryker. The authors have rightly described the need to flex the knee to 110°. The article also precisely highlights the potential pitfall of the system: reamer breakage. However, I differ with this view of the authors: “Using an initial 4.5-mm reamer is often advantageous as it allows for button fixation passage out over the lateral wall of the femur and for accurately measuring the femoral tunnel length. Using a 4.5-mm reamer also allows mobility of the nitinol guide wire and can position the final reamer slightly superior or more toward the [posterolateral] bundle footprint; this is useful if the nitinol guide wire is initially positioned slightly inferior or too close to the [anteromedial] bundle footprint.”1 (p4) The 4.5-mm reamer must not be used before the reaming of the proposed femoral tunnel to the desired dimension and desired length, usually by an 8- or 9-mm reamer. To elaborate, the flexible guide wire remains in the femoral tunnel, binded by the cortex of the lateral femoral condyle and by lateral femoral condylar bone. The initial reamer that we use is determined by the diameter of the graft, usually 8 or 9 mm. This reamer is not blown through and through the lateral femoral condyle, and we usually leave 5 to 10 mm of lateral wall so that the guide wire does not leave its purchase in the bone and does not move with the reamers. This, in turn, allows a reasonable length of flexible guide wire coming out of the medial portal. As well, this leads to a long contact between the flexible guide wire and flexible reamer, thereby decreasing the possibility of reamer breakage. After this step, the 4.5-mm reamer is used so as to allow flipping of the suspensory fixation system that we intend to use. Additionally, I also differ with the authors’ view of using a fixed 55° tibial guide. The entry point of the tibial guide wire on the anteromedial tibial surface must be the determinant to the tibial guide angle and not vice versa.

Transportal femoral drilling creates more horizontal ACL graft orientation compared to transtibial drilling: A 3D CT imaging study

BackgroundThe principle of anatomic anterior cruciate ligament (ACL) reconstruction is to create a femoral and tibial tunnel that resembles the insertion of the native ACL. Anatomic reconstruction leads to a more horizontal graft orientation that provides more rotational stability.The aim of this study is to investigate the best method to achieve anatomical reconstruction of femoral insertion of the ACL and thus, a more horizontal orientation of the ACL. We compared tunnel position and orientation between transportal femoral drilling technique and transtibial technique. MethodsThirty-two patients were included. Post-operative CT scans were obtained and femur, tibia and ACL tunnels were reconstructed. The position and orientation of tibial and femoral tunnels were quantified using the quadrant method, and femoral tunnel length, ellipticity and posterior wall breakage were assessed. We also investigated clinical outcome. ResultsAnalyses show that transportal drilled femoral tunnels were situated significantly lower than transtibial drilled tunnels (p<0.0001), resulting in a significantly more horizontal oriented ACL in the transportal group in coronal (p<0.0001) and sagittal plane (p=0.01). No differences were observed in depth of femoral tunnel position (p=0.44). Femoral tunnel length was shorter in the transportal group (p=0.01) with a more ellipsoidal femoral aperture (p=0.01). There were no differences between both groups in tibial position. There were no differences in clinical outcome measure between the transportal and transtibial groups. ConclusionThis study indicates that transportal drilling of the femoral tunnel leads to a more horizontal graft orientation of the ACL, without differences in clinical outcome.

Graft Bending Angle at the Intra-articular Femoral Tunnel Aperture After Single-Bundle Posterior Cruciate Ligament Reconstruction

Background: To date, no in vivo 3-dimensional computed tomography (3D-CT) studies have compared graft bending angles at the femoral tunnel aperture and femoral tunnel length in patients who underwent posterior cruciate ligament (PCL) reconstruction with outside-in (OI) and inside-out (IO) techniques. Purpose/Hypothesis: This study used in vivo 3D-CT analysis to compare graft bending angles at the femoral tunnel aperture and femoral tunnel lengths after OI and IO femoral drilling techniques in single-bundle PCL reconstruction. It was hypothesized that the graft bending angle at the femoral tunnel aperture would be less acute with the OI compared with the IO technique, with no difference in femoral tunnel lengths. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Immediate postoperative in vivo 3D-CT and curved planar reformation were used to assess the graft bending angles and femoral tunnel lengths in the sagittal, axial, and coronal planes in 67 patients who underwent single-bundle PCL reconstruction with the OI (n = 37) and IO (n = 30) techniques. Results: The mean graft bending angles on the sagittal and axial planes were 8.2° more acute (23.5° vs 15.3°, P = .011) and 5.3° more acute (49.0° vs 43.7°, P = .013), respectively, with the IO compared with the OI technique, but the difference in the coronal plane was not statistically significant (25.3° vs 24.8°, P = .623). Femoral tunnel length was similar in the 2 groups. Conclusion: The graft bending angles in single-bundle PCL reconstruction were more acute in the sagittal and axial planes with the IO compared with the OI technique, but there was no difference in the coronal plane. In addition, femoral tunnel lengths did not differ significantly in patients who underwent OI and IO single-bundle PCL reconstructions. Although further biomechanical studies are needed to evaluate the effect on graft failure of a <10° difference in graft bending angle, the small magnitude of this difference would likely have little adverse effect on graft survival.

The correlation of femoral tunnel length with the height and area of the lateral wall of the femoral intercondylar notch in anatomical single-bundle ACL reconstruction.

The purpose of this study was to reveal the correlation between femoral tunnel length and the height and area of the lateral wall of the femoral intercondylar notch in anatomical single-bundle anterior cruciate ligament (ACL) reconstruction . Twenty-four subjects undergoing anatomical single-bundle ACL reconstruction were included in this study (19 females and 5 males; average age 45.5±16.7). In the anatomical single-bundle ACL reconstruction, the femoral and tibial tunnels were created close to the anteromedial bundle insertion site. Using post-operative three-dimensional computed tomography (3D-CT), an accurate lateral view of the femoral condyle was evaluated. The correlation of femoral tunnel length, which was measured intra-operatively, with the length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch was statistically analysed. Tunnel placement was also evaluated using 3D-CT (Quadrant method). The average femoral tunnel length was 35.3±4.9mm. The length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch were 33.6±3.4, 22.8±2.4, and 734.6±136mm2, respectively. Both the height and the area of the lateral wall of the femoral intercondylar notch were significantly correlated with femoral tunnel length. Femoral tunnel placement was 24.1±3.9% in a shallow-deep direction, and 33.5±7.7% in a high-low direction. The height and area of the lateral wall of the femoral intercondylar notch are correlated with femoral tunnel length in anatomical single-bundle ACL reconstruction. For clinical relevance, surgeons should be careful not to make the femoral tunnel too short in knees in which the femoral intercondylar notch is low in height or small in size. Case-controlled study, Level III.

Comparison of Femoral Tunnel Length and Obliquity Between Transtibial, Anteromedial Portal, and Outside-In Surgical Techniques in Single-Bundle Anterior Cruciate Ligament Reconstruction: A Meta-analysis

It is unclear whether femoral tunnel length and obliquity differ after transtibial and independent femoral drilling techniques of anterior cruciate ligament (ACL) reconstruction. This meta-analysis therefore compared femoral tunnel length and obliquity in patients who underwent ACL reconstruction by the transtibial, anteromedial (AM) portal, and outside-in (OI) techniques. In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, all studies comparing femoral tunnel length and obliquity with various measurement tools-from direct measurement to imaging methods such as plain radiography, computed tomography, or magnetic resonance imaging-in patients who underwent reconstruction by the transtibial or independent femoral drilling (AM portal or OI) techniques were included. Fourteen studies were included in the meta-analysis. The femoral tunnel length was 7.8 to 11.0 mm longer (P < .05) and coronal obliquity was 7.5° to 29.1° more vertical (P < .05) with the transtibial technique than with the AM portal or OI technique. Femoral tunnel and graft obliquity in the sagittal plane, however, did not differ significantly (P > .05). ACL reconstruction using the AM portal and OI femoral drilling techniques resulted in a shorter length and greater coronal obliquity of the femoral tunnel than did the transtibial technique. However, these 3 femoral drilling techniques resulted in similar obliquities of the femoral tunnel and graft in the sagittal plane. Level III, meta-analysis.