Anterior Cruciate Ligament Tibial Footprint Research Articles

What Effect Does Anterior Cruciate Ligament Tibial Guide Orientation Have on Tibial Tunnel Length?

To evaluate the effects of alteration in tibial guide pin insertion angle and external starting point on tibial tunnel length for anterior cruciate ligament (ACL) reconstruction. Ten cadaveric tibial specimens were used. One pin was placed at each of variable insertion angles (55°, 50°, and 45°) of the tibial targeting device aimed at the center of the tibial ACL footprint. These 3 pins started externally along the anterior border of the superficial medial collateral ligament. A fourth pin at 50° was placed at a different external tibial starting point 1.5 cm anterior to the anterior border of the superficial medial collateral ligament. The intraosseous length of each pin was measured. Statistic analyses were performed with the Kruskal-Wallis test, with significance set at P < .05. The mean length for the 55° tibial tunnel was 50.3 mm (range, 42 to 56 mm); for the 50° tunnel, it was 48.9 mm (range, 44 to 55 mm); for the 50° anterior tunnel, it was 47.6 mm (range, 39 to 55 mm); and for the 45° tunnel, it was 47.3 mm (range, 41 to 52 mm). Changing the angle of the tibial guide did not significantly affect the length of the tibial tunnel (P = .18). Changing the external tibial starting point did not affect the length of the tibial tunnel (P = .39). Changing the tibial guide angle between 45°, 50°, and 55° does not appreciably change tibial tunnel length. Moving the starting point anterior 1.5 cm toward the tibial tubercle also has no effect on the tibial tunnel length. The lack of significant changes in tunnel length with these interventions may reflect the associated changes that occur in proximal tibial morphometry with change in external tibial starting position. Changing tibial tunnel length in ACL reconstruction likely requires more distalization of the external tibial starting point than is achieved simply by altering the tibial aiming guide angle by 10° or less.

A 3.5-mm-Diameter Anterior Cruciate Ligament Tibial Retrograde Socket Drilling Pin Is More Accurate Than a 2.4-mm-Diameter Pin

The purpose of this study was to evaluate the accuracy of a 3.5-mm-diameter anterior cruciate ligament (ACL) tibial retrograde socket drilling pin versus a standard, 2.4-mm drill-tipped guide pin. A secondary purpose was to evaluate surgeon precision in identifying the true (anatomic) center of the ACL tibial footprint using arthroscopic visualization. Six matched pairs of cadaveric knees were disarticulated, leaving a well-defined footprint of the ACL on the tibial plateau. The tibial footprint was digitally recorded by a bioengineer, and the true center of the footprint was calculated. Next, using arthroscopic visualization, a surgeon identified and marked his estimation of the true center of the ACL tibial footprint. This mark was then digitally recorded by the bioengineer and compared with the calculated center, allowing quantification of surgeon anatomic precision. Finally, under arthroscopic visualization, the surgeon was given 1 attempt to aim and drill the guide pin to his mark. Pin position was digitally recorded; the distance of the drill pin from the mark quantified drill pin placement accuracy. Mean accuracy for the 3.5-mm retrograde socket drilling pin was 1.06 ± 0.75 mm versus 3.03 ± 1.00 mm for the 2.4-mm pin. The difference was significant (P < .005). Surgeon anatomic precision was 2.7 ± 1.4 mm. Our results show that a 3.5-mm-diameter ACL tibial retrograde socket drilling pin is significantly more accurate than a 2.4-mm-diameter pin. The 3.5-mm pin accuracy is within the range of surgeon precision; the 2.4-mm pin accuracy is not. Pin accuracy and surgeon precision are clinically relevant measures because anatomic tunnel placement is a determinant of ACL reconstruction outcome.

Transtibial Versus Anteromedial Portal Reaming in Anterior Cruciate Ligament Reconstruction: An Anatomic and Biomechanical Evaluation of Surgical Technique

The purpose of this study was to objectively evaluate the anatomic and biomechanical outcomes of anterior cruciate ligament (ACL) reconstruction with transtibial versus anteromedial portal drilling of the femoral tunnel. Ten human cadaveric knees (5 matched pairs) without ligament injury or pre-existing arthritis underwent ACL reconstruction by either a transtibial or anteromedial portal technique. A medial arthrotomy was created in all cases before reconstruction to determine the center of the native ACL tibial and femoral footprints. A 10-mm tibial tunnel directed toward the center of the tibial footprint was prepared in an identical fashion, starting at the anterior border of the medial collateral ligament in all cases. For transtibial femoral socket preparation (n = 5), a guidewire was placed as close to the center of the femoral footprint as possible. With anteromedial portal reconstruction (n = 5), the guidewire was positioned centrally in the femoral footprint and the tunnel drilled through the medial portal in hyperflexion. An identical graft was fixed and tensioned, and knee stability was assessed with the following standardized examinations: (1) anterior drawer, (2) Lachman, (3) maximal internal rotation at 30°, (4) manual pivot shift, and (5) instrumented pivot shift. Distance from the femoral guidewire to the center of the femoral footprint and dimensions of the tibial tunnel intra-articular aperture were measured for all specimens. Statistical analysis was completed with a repeated-measures analysis of variance and Tukey multiple comparisons test with P ≤ .05 defined as significant. The anteromedial portal ACL reconstruction controlled tibial translation significantly more than the transtibial reconstruction with anterior drawer, Lachman, and pivot-shift examinations of knee stability (P ≤ .05). Anteromedial portal ACL reconstruction restored the Lachman and anterior drawer examinations to those of the intact condition and constrained translation with the manual and instrumented pivot-shift examinations more than the native ACL (P ≤ .05). Despite optimal guidewire positioning, the transtibial technique resulted in a mean position 1.94 mm anterior and 3.26 mm superior to the center of the femoral footprint. The guidewire was positioned at the center of the femoral footprint through the anteromedial portal in all cases. The tibial tunnel intra-articular aperture was 38% larger in the anteroposterior dimension with the transtibial versus anteromedial portal technique (mean, 14.9 mm v 10.8 mm; P ≤ .05). The anteromedial portal drilling technique allows for accurate positioning of the femoral socket in the center of the native footprint, resulting in secondary improvement in time-zero control of tibial translation with Lachman and pivot-shift testing compared with conventional transtibial ACL reconstruction. This technique respects the native ACL anatomy but cannot restore it with a single-bundle ACL reconstruction. Eccentric, posterolateral positioning of the guidewire in the tibial tunnel with the transtibial technique results in iatrogenic re-reaming of the tibial tunnel and significant intra-articular aperture expansion. Anteromedial portal drilling of the femoral socket may allow for improved restoration of anatomy and stability with ACL reconstruction compared with conventional transtibial drilling techniques.

Postoperative evaluation of tibial footprint and tunnels characteristics after anatomic double-bundle anterior cruciate ligament reconstruction with anatomic aimers

Following anatomic double-bundle anterior cruciate ligament (ACL) reconstruction with hamstring tendon autografts, 38 consecutive patients were evaluated with high-speed three-dimensional computed tomography. Scans were performed within 3 days following surgery. The length and width of the reconstructed ACL footprint were measured on axial images. Then, 3D images were converted into 2D with radiologic density for measurement purposes. Tunnel orientation was measured on AP and lateral views. In the sagittal plane, the center of the anteromedial (AMB) and posterolateral bundle (PLB) tibial attachment positions was calculated as the ratio between the geometric insertion sites with respect to the sagittal diameter of the tibia. In addition, the length from the anterior tibial plateau to the retro-eminence ridge was measured; the relationship of this line with the centers of the AM and PL tunnels was then measured. The AP length of the reconstructed footprint was 17.1 mm ± 1.9 mm and the width 7.3 mm ± 1.2 m. The distance from retro-eminence ridge to center of AM tunnel was 18.8 mm ± 2.8 mm, and the distance from RER to center of PL tunnel was 8.7 mm ± 2.6 mm. The distance between tunnels center was 10.1 mm ± 1.7 mm. There were no significant differences between the intra- and inter-observer measurements. The bone bridge thickness was 2.1 mm ± 0.8 mm. In the sagittal plane, the centers of the tunnel apertures were located at 35.7% ± 6.7% and 53.7% ± 6.8% of the tibia diameter for the AMB and PLB, respectively. The surface areas of the tunnel apertures were 46.3 mm(2) ± 4.4 mm(2) and 36.3 mm(2) ± 4.0 mm(2) for the AM and PL tunnels, respectively. The total surface area occupied by both tunnels was 82.6 mm(2) ± 7.0 mm(2). In the coronal plane, tunnel orientation showed the AM tunnel was more vertical than the PL tunnel with a 10° divergence (14.8° vs. 24.1°). In the sagittal plane, both tunnels were almost parallel (29.9° and 25.4° for the AM and PL tunnels, respectively). When using anatomic aimers, the morphometric parameters of the reconstructed tibial footprint in terms of length and distances to the surrounding bony landmarks were similar to the native ACL tibial footprint. However, the native footprint width was not restored, and the surface area of the two tunnel apertures was in the lower range of the published values for the native footprint area.

Anterior Cruciate Ligament Tibial Guide Pin Accuracy and Surgical Precision: Comparing 3.0-mm and 2.4-mm Guide Pins

The purpose of this study was to evaluate the accuracy of a 3.0-mm-diameter anterior cruciate ligament (ACL) tibial guide pin versus a standard, 2.4-mm drill-tipped guide pin. A secondary purpose was to evaluate surgeon precision in identifying the true (anatomic) center of the ACL tibial footprint using arthroscopic visualization. Five matched pairs of cadaveric knees were disarticulated, leaving a well-defined footprint of the ACL on the tibial plateau. The tibial footprint was digitally recorded by a bioengineer, and the true center of the footprint was calculated. Next, using arthroscopic visualization, a surgeon identified and marked his estimation of the true center of the ACL tibial footprint. This mark was then digitally recorded by the bioengineer and compared with the calculated center, allowing quantification of surgeon anatomic precision. Finally, under arthroscopic visualization, the surgeon was given 1 attempt to aim and drill the guide pin to his mark. Pin position was digitally recorded; the distance of the drill pin from the mark quantifies drill pin placement accuracy. Mean accuracy for the 3.0-mm guide pin was 2.87 +/- 1.19 mm versus 6.98 +/- 1.29 mm for the 2.4-mm pin. The difference was significant (P = .005). Surgeon anatomic precision was 3.32 +/- 2.10 mm. Our results show that a 3-mm ACL tibial guide pin is significantly more accurate than a 2.4-mm-diameter pin. The 3-mm pin accuracy is within the range of surgeon precision; the 2.4-mm pin accuracy is not. Pin accuracy and surgeon precision are clinically relevant measures because anatomic tunnel placement is a determinant of ACL reconstruction outcome.

Anatomical analysis of the anterior cruciate ligament femoral and tibial footprints

BackgroundThe current trend in anterior cruciate ligament (ACL) reconstruction has shifted to anatomical double-bundle (DB) reconstruction, which reproduces both the anteromedial bundle (AMB) and the posterolateral bundle (PLB) of the ACL. Navigation systems have also been recently introduced to orthopedic surgical procedures, including ACL reconstruction. In DB–ACL reconstruction, the femoral and tibial tunnel positions are very important, but a representation of the ACL footprint under an arthroscopic view has not been established even though navigation systems have been introduced. The purpose of this study was to evaluate the anatomical footprints of both the AMB and the PLB using the representation method for application to arthroscopic DB–ACL reconstruction using a navigation system, and to evaluate the validity of the currently determined footprint position compared with other representation methods. MethodsThirty-six cadaveric knees were used for an anatomical evaluation of footprints of the AMB and PLB. On the tibial side, the ACL footprints were evaluated using an original method. On the femoral side, the ACL footprints were evaluated using Watanabe’s method and three other methods: (1) the quadrant method, (2) Mochizuki’s method, and (3) Takahashi’s method. ResultsThe central points of the ACL footprints were represented almost constantly. The present data is in accordance with previous measurement data. ConclusionThis study showed that the anatomical data of the ACL femoral and tibial footprints determined with Watanabe’s method at the femoral side and our original method at the tibial side were both applicable to arthroscopic surgery with a navigation system.

Anatomy of the Anterior Cruciate Ligament with Regard to Its Two Bundles

The anterior cruciate ligament (ACL) consists of two major fiber bundles, namely the anteromedial and posterolateral bundle. When the knee is extended, the posterolateral bundle (PL) is tight and the anteromedial (AM) bundle is moderately lax. As the knee is flexed, the femoral attachment of the ACL becomes a more horizontal orientation; causing the AM bundle to tighten and the PL bundle to relax. There is some degree of variability for the femoral origin of the anterome-dial and posterolateral bundle. The anteromedial bundle is located proximal and anterior in the femoral ACL origin (high and deep in the notch when the knee is flexed at 90 degrees ); the posterolateral bundle starts in the distal and posterior aspect of the femoral ACL origin (shallow and low when the knee is flexed at 90 degrees ). In the frontal plane the anteromedial bundle origin is in the 10:30 clock position and the postero-lateral bundle origin in the 9:30 clock position. At the tibial insertion the ACL fans out to form the foot region. The anteromedial bundle insertion is in the anterior part of the tibial ACL footprint, the posterolateral bundle in the posterior part. While the anteromedial bundle is the primary restraint against anterior tibial translation, the posterolateral bundle tends to stabilize the knee near full extension, particularly against rotatory loads.

Morphometric side-to-side differences in human cruciate ligament insertions

Graft placement in cruciate ligament reconstruction is known to significantly influence postoperative knee stability and range of motion. Improvement of bone tunnel positioning has been advocated by computer-assisted surgical procedures that require reliable input and reference data. This study validates the hypothesis that morphometric reference data can be obtained from the uninjured controlateral knee for accurate bone tunnel and graft positioning. Thirty pairs of human cadaver knees were dissected and the femoral and tibial footprints of the anterior and posterior cruciate ligaments (PCL) were radiopaquely marked. Radiographs were taken of the corresponding left- and right-sided femora and tibiae, and digitally processed. Controlateral specimens were mirrored and overlapped precisely, the areas and intersections of ligament insertion were digitally determined. There were no significant differences in the total area of cruciate ligament insertion between left and right knee specimens or between female and male specimens. Intersection areas (IAs) in femoral and tibial anterior cruciate ligament (ACL) insertions averaged 31.3 and 33.4% of the total insertion area, respectively. The center of gravity for the femoral and tibial ACL footprint differed by 4.7 and 4.5 mm between left and right knees, respectively. IAs in femoral and tibial PCL insertions averaged 46.1 and 61.3% of the total insertion area, respectively. The center of gravity for the femoral and tibial PCL footprint differed by 4.5 and 2.4 mm between left and right knees, respectively. Our study does not support the concept of obtaining morphologic reference data from the uninjured controlateral knee for individual bone tunnel placement.

The biology of integration of the anterior cruciate ligament

The anterior cruciate ligament (ACL) is a short, stout, intra-articular, extrasynovial structure which acts to control rotational movements and anterior translation of the femur upon the fixed tibia.[1][1] Rupture is a traumatic event, often as a consequence of twisting upon the weight-bearing limb