Femoral Attachment Of Anterior Cruciate Ligament Research Articles

Anatomic attachment of the ACL. Comparison between radiological and CT analysis

The following hypothesis was tested: the location of the tibial and femoral anterior cruciate ligament (ACL) attachments will differ according to the measurement technique (plain radiographs or CT-scan) in relation to the anatomic frame of reference. 10 gross specimens were studied. The location of metallic reference pins implanted around the tibial and femoral ACL attachments was recorded with reference to the bone contours with a caliper on the anatomic preparation, with standard plain AP and lateral radiographs and with a CT-scan. Results were compared with appropriate statistical tests at a 0.05 level of significance. The mean ratio between the antero-posterior tibia measurement and the center of the ACL tibial attachment varied from 50 to 52%. The mean ratio between the medio-lateral tibia measurement and the center of the ACL tibial attachment varied from 49 to 51%. The mean ratio between the antero-posterior femur measurement and the center of the ACL femoral attachment varied from 74 to 80%. The results were significantly different between the three techniques (respectively P=0.003, P=0.02 and P=0.045). The paired differences were small (3% at the tibia, 6% at the femur). There was a strong correlation and a good agreement between the three techniques. It is likely that the small differences on the tibia have few, if any, clinical relevance. Both radiographic and CT-scan measurement techniques used during the present study have the potential to be used as quality control after ACL replacement. Diagnostic study-investigating a diagnostic test. Development of diagnostic criteria in a consecutive series of patients and a universally applied "gold" standard, Level II.

Arthroscopically Pertinent Landmarks for Tunnel Positioning in Single-Bundle and Double-Bundle Anterior Cruciate Ligament Reconstructions

Background: Quantification of the overall anterior cruciate ligament (ACL) and anteromedial (AM) and posterolateral (PL) bundle centers in respect to arthroscopically pertinent bony and soft tissue landmarks has not been thoroughly assessed. Hypothesis: A standardized anatomical measurement method can quantitate the locations of the ACL and AM and PL bundle centers in reference to each other and anatomical landmarks. Study Design: Descriptive laboratory study. Methods: Quantification of the ACL and its bundle attachments was performed on 11 cadaveric knees using a radio frequency-tracking device. Results: The tibial ACL attachment center was 7.5 mm medial to the anterior horn of the lateral meniscus, 13.0 mm anterior to the retro-eminence ridge, and 10.5 mm posterior to the ACL ridge. The femoral ACL attachment center was 1.7 mm proximal to the bifurcate ridge and 6.1 mm posterior to the lateral intercondylar ridge. The tibial AM attachment center was 8.3 mm medial to the anteromedial aspect of the lateral meniscus anterior horn, 17.8 mm anterior to the retro-eminence ridge, and 5.6 mm posterior to the ACL ridge. The femoral AM attachment center was 4.8 mm proximal to the bifurcate ridge and 7.1 mm posterior to the lateral intercondylar ridge. The tibial PL bundle attachment center was 6.6 mm medial to the posteromedial aspect of the lateral meniscus anterior horn, 10.8 mm anteromedial to the root attachment of the lateral meniscus posterior horn, and 8.4 mm anterior to the retro-eminence ridge. The femoral PL bundle attachment center was 5.2 mm distal to the bifurcate ridge and 3.6 mm posterior to the lateral intercondylar ridge. Conclusion: The authors developed a comprehensive compilation of measurements of arthroscopically pertinent bony and soft tissue landmarks that quantitate the ACL and its individual bundle attachment centers on the tibia and femur. Clinical Relevance: These clinically relevant arthroscopic landmarks may enhance single- and double-bundle ACL reconstructions through improved tunnel placement.

Bone-to-Bone Fixation Enhances Functional Healing of the Porcine Anterior Cruciate Ligament Using a Collagen-Platelet Composite

The purpose of this study was to determine whether providing bony stabilization between the tibia and femur improves the structural properties of an "enhanced" anterior cruciate ligament (ACL) repair using a collagen-platelet composite when compared with the traditional (Marshall) suture technique. Twelve pigs underwent unilateral ACL transection and were treated with sutures connecting the bony femoral ACL attachment site to the distal ACL stump (ligament group) or to the tibia through a bone tunnel (tibia group). A collagen-platelet composite was placed around the sutures to enhance the biological repair in both groups. Anteroposterior knee laxity and the graft structural properties were measured after 15 weeks of healing in both the ACL-repaired and contralateral, ACL-intact joints. Enhanced ACL repair with bone-to-bone fixation significantly improved yield load and linear stiffness of the ACL repairs (P < .05) after 15 weeks of healing. However, laxity values of the knees were similar in both groups of repaired knees (P > .10). Using an enhanced ACL suture repair technique that includes bone-to-bone fixation to protect the repair in the initial healing stages resulted in an ACL with improved structural properties after 15 weeks in the porcine model. The healing response of an ACL suture repair by use of a collagen-platelet composite can be enhanced by providing bony stabilization between the tibia and femur to protect the graft during the initial healing process in a translational model.

Replication of the Range of Native Anterior Cruciate Ligament Fiber Length Change Behavior Achieved by Different Grafts

Background The native anterior cruciate ligament (ACL) does not behave as a simple bundle of fibers with constant tension but as a continuum of ligament fibers with differential length change during knee flexion/extension. Computer-assisted navigation can be used to assess length change in different fibers within the native ACL and to evaluate how different reconstruction grafts replicate the range of native ligament fiber length change behavior. Hypothesis Anterior cruciate ligament reconstruction graft size and configuration (single- vs double-bundle) are deciding factors as to how much of the native ACL fiber length change behavior is replicated. Study Design Controlled laboratory study. Methods The fiber length change behavior of the entire native ACL was assessed by measuring the length change pattern of representative anteromedial (AM) and posterolateral (PL) bundle fibers (1 at the center and 4 at the periphery of each bundle). The tibial and femoral ACL attachment areas in 5 fresh-frozen cadaveric knees were digitized, and the length change of each representative fiber was recorded during knee flexion/extension using an image-free, optical navigation system. Subsequently, single-bundle ACL reconstructions of different diameters (6, 9, and 12 mm) positioned at the center of the overall native femoral and tibial attachment sites were modeled to assess how much of the range of ligament fiber length change of the native ligament was captured. This was compared with a double-bundle graft using 6-mm-diameter AM and PL grafts positioned at the centers of the femoral and tibial attachment sites of each separate bundle. Results The 6-, 9-, and 12-mm single-bundle grafts simulated 32%, 51%, and 66% of the ligament fiber length change behavior of the native ACL, respectively. The length change patterns in these grafts were similar to the central fibers of the native ACL: the PL fibers of the AM bundle and AM fibers of the PL bundle. However, even a 12-mm graft did not represent the most AM and PL native fibers. The 6-mm AM and PL bundle grafts (equivalent in cross-sectional area to a 9-mm single-bundle graft) simulated 71% of the native ACL and better captured the extremes of the range of native ligament fiber length change. Conclusion Increasing single-bundle graft size appears to capture more of the range of native ACL fiber length change. However, for a similar graft cross-sectional area, a 2-bundle graft simulates the length change behavior of the native ligament more precisely and thus may better emulate the synergistic actions of anisometric and isometric fibers of the native ligament in restraining knee laxity throughout the range of flexion. Clinical Relevance The range of native ACL fiber length change behavior is better replicated by larger diameter grafts but may be best reproduced by double-bundle reconstruction.

Primary Repair Combined with Bone Marrow Stimulation in Acute Anterior Cruciate Ligament Lesions

Background The anterior cruciate ligament has been shown to have poor healing ability, and reconstruction is the standard treatment. Hypothesis Primary anterior cruciate ligament repair combined with bone marrow stimulation could restore stability and function in athletes with acute anterior cruciate ligament incomplete tears. Study Design Case series; Level of evidence, 4. Methods Among a group of 99 patients with clinically diagnosed anterior cruciate ligament acute lesions, 26 athletes with arthroscopically confirmed incomplete anterior cruciate ligament proximal tears were treated with primary repair combined with bone marrow stimulation of the anterior cruciate ligament femoral attachment site. Postoperatively, all patients underwent a specific rehabilitation program. All patients were prospectively evaluated; outcome measures were assessed using Marx, Noyes, Tegner, Single Assessment Numeric Evaluation, Lysholm, and International Knee Documentation Committee scores. Anterior tibial translation was measured using Rolimeter instrument under anesthesia and at final follow-up. Results All athletes were followed up for a mean 25.3 months (range, 17-38 months). Mean age was 26.6 years. Mean preinjury Tegner was 7.1 (SD, 1.1) and final Tegner 6.7 (SD, 1.4); mean preinjury Marx was 11.0 (SD, 3.4) and final Marx 9.6 (SD, 3.1); mean preinjury Noyes was 82.5 (SD, 5.8) and final Noyes 83.3 (SD, 7.2). These scores were not statistically different at P values of. 020,. 011, and. 303, respectively. Final Single Assessment Numeric Evaluation rating was significantly lower than was preinjury Single Assessment Numeric Evaluation rating. This was mainly related to decreased self-confidence in high-risk sports and fear of new injury. Final Single Assessment Numeric Evaluation rating and Tegner scores were significantly higher than were their respective preoperative values. Mean Rolimeter side-to-side difference of anterior knee translation was significantly reduced from 3.5 mm (SD, 0.7) preoperatively to 1.3 mm (SD, 0.8) postoperatively. Conclusion In this athletic population, anterior cruciate ligament primary repair in acute incomplete lesion combined with bone marrow stimulation effectively restored knee stability and function.

Osseous Landmarks of the Femoral Attachment of the Anterior Cruciate Ligament: An Anatomic Study

Anatomic tunnel placement is critical to the success of anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to determine qualitatively and quantitatively the osseous landmarks of femoral attachment of the ACL. The femoral attachment of the ACL was studied histologically in seven human fetuses, arthroscopically in 60 patients who underwent ACL surgery, and grossly in 16 cadaveric knees. Three-dimensional laser digitizer pictures of the cadaveric specimens were taken to quantify length, area, and angulations of the femoral attachment of the ACL. Two different osseous landmarks were detected. An osseous ridge that runs from proximal to distal ends was present in all the arthroscopic patients and cadaveric knees. It was named "lateral intercondylar ridge." Another osseous landmark between the femoral attachment of the anteromedial (AM) and posterolateral (PL) bundles running from anterior to posterior was observed in 6 out of 7 fetuses, 49 out of 60 arthroscopic patients, and 13 out of 16 cadaveric knees. It was named "lateral bifurcate ridge." A change of slope between the femoral attachment of the AM and PL bundles was observed in all specimens studied. The femoral attachment of the AM bundle formed an angle with the PL bundle of 27.6 degrees +/- 8.8 degrees and a radius of curvature of 25.7 +/- 12 mm. The area of the entire ACL footprint, AM, and PL bundle was 196.8 +/- 23.1 mm(2), 120 +/- 19 mm(2), and 76.8 +/- 15 mm(2), respectively. The ACL femoral attachment has a unique topography with a constant presence of the lateral intercondylar ridge and often an osseous ridge between AM and PL femoral attachment, the lateral bifurcate ridge. These findings may assist surgeons to perform ACL surgery in a more anatomic fashion.

Anatomical Limitations of Transtibial Drilling in Anterior Cruciate Ligament Reconstruction

Background Recommended techniques for transtibial drilling in anterior cruciate ligament reconstruction are based on strategies to prevent graft impingement and preserve tibial tunnel length. The limitations of this drilling technique may restrict the ability to centralize tunnels in the anterior cruciate ligament footprints. Hypothesis A transtibial drilling starting point to centralize the tibial and femoral tunnels in their respective footprints can be identified, but it will result in a short tibial tunnel. Study Design Descriptive laboratory study. Methods The femoral and tibial attachments of the anterior cruciate ligament were characterized in 12 fresh-frozen cadaveric knees. Knees were secured in 70° and 90° of flexion. A guide pin was drilled antegrade through the central femoral and proximal anterior cruciate ligament attachment sites through the central tibial anterior cruciate ligament attachment site to exit on the anterior tibia. Results In 90° of flexion using the central femoral and tibial attachment sites, the exit point of the pin on the anterior tibia was 14.1 mm from the tibial joint line and 20.9 mm anterior to the superficial medial collateral ligament. The length of the pin in the tibia was 30.6 mm. Extending the knee to 70° or directing the pin through the proximal femoral anterior cruciate ligament attachment moved the starting point less than 4 mm from this point. Conclusion The transtibial technique can produce tunnels centered in the anterior cruciate ligament footprints, but a starting point close to the tibial joint line is required. This will result in a relatively short tibial tunnel. Clinical Relevance If tunnels centered in the anterior cruciate ligament attachment sites are desired with the transtibial drilling technique, then a short tibial tunnel is necessary. A short tibial tunnel may compromise graft fixation and graft incorporation, or it may result in a tunnel length—graft length mismatch. An alternative drilling strategy might be employed.

Cadaveric Knee Observation Study for Describing Anatomic Femoral Tunnel Placement for Two-Bundle Anterior Cruciate Ligament Reconstruction

The recently developed 2-bundle anterior cruciate ligament (ACL) reconstruction lacks sufficient anatomic background. The purpose of this anatomic study was to describe functional anteromedial (AM) and posterolateral (PL) portions of the natural ACL and to provide a reproducible description of the graft placement. Our hypothesis was that the core functional area of the femoral ACL attachment will be revealed by removing the surface fibrous membranous tissue of the ACL midsubstance and the attachment area. The natural ACL was divided into 2 portions of AM and PL bundles in a flexion position; those bundles were most clearly defined when the knee was in flexion. The surface membrane of the ACL was removed and the margin was marked. The attachment site was removed after documenting its measurements. The knee position was corrected by digital photographs with the femoral bone in the correct lateral position. The length of the major axis of the AM and PL bundles averaged 9.2 +/- 0.7 mm and 6.0 +/-0.8 mm, respectively. Both lengths of the minor axis of AM and PL bundles averaged 4.7 +/-0.6 mm. The distance from the attachment center of each AM and PL bundle to the posterior bone and articular surface border averaged 6.3 +/- 0.6 mm and 8.6 +/- 0.6 mm, respectively. The center of the AM and PL bundles was described as 1:40 and 3:10 clock positions, respectively, as left knee when the point was defined on the "lateral wall clock" of the intercondylar notch. The study described the position and area of each 2-bundle of AM and PL portions of the natural ACL by describing its central structure with the surface membrane removed. The detailed anatomic description of the natural ACL femoral attachment might suggest to surgeons where to make femoral tunnels during 2-bundle reconstruction.

Sagittal Plane Imaging Parameters for Computer-Assisted Fluoroscopic Anterior Cruciate Ligament-Reconstruction

Reproducible graft placement in anterior cruciate ligament (ACL) reconstructions is considered to be a critical factor affecting the successful clinical outcome of the procedure. Many current ACL instrument systems rely on intra-articular landmarks to guide the ACL tunnel placement. However, most of these instrument systems use mobile soft tissues as landmarks. We hypothesize that consistently identifiable radiographic contour landmarks can be established that can be used to improve the reproducibility of graft tunnel placement in fluoroscopically and computerassisted ACL reconstructions. For the tibia, magnetic resonance imaging (MRI) scans showed the average ACL attachment site to be projected at 46% on a line extending from the anterior to the posterior cortices. Intraoperative fluoroscopic images were checked for the reproducibility of this line and its clinical use. For the femur, lateral radiographs demonstrated a consistent relationship between the intercondylar roof line (Blumensaat's line) and the nearly circular profile of the posterior and inferior contour of the lateral femoral condyle. The middle of this circular profile is consistently projected on Blumensaat's line at 66% of its anterior-to-posterior direction. Intraoperative images were used, which showed the aiming drill at the point of entering the lateral femoral condyle. Instead of determining the femoral attachment site relative to Blumensaat's line, we can thus determine its position relative to the center of the circle. Based on intraoperative x-rays, the proposed femoral ACL attachment site can be projected on a line parallel with the Blumensaat's line from the circle center in the posterior direction. Our results indicate that there are consistently identifiable radiographic features on the tibia and femur contours that can be used for fluoroscopic and computer-assisted guidance of ACL graft placement.

Sagittal plane imaging parameters for computer-assisted fluoroscopic anterior cruciate ligament reconstruction.

Reproducible graft placement in anterior cruciate ligament (ACL) reconstructions is considered to be a critical factor affecting the successful clinical outcome of the procedure. Many current ACL instrument systems rely on intra-articular landmarks to guide the ACL tunnel placement. However, most of these instrument systems use mobile soft tissues as landmarks. We hypothesize that consistently identifiable radiographic contour landmarks can be established that can be used to improve the reproducibility of graft tunnel placement in fluoroscopically and computer-assisted ACL reconstructions. For the tibia, magnetic resonance imaging (MRI) scans showed the average ACL attachment site to be projected at 46% on a line extending from the anterior to the posterior cortices. Intraoperative fluoroscopic images were checked for the reproducibility of this line and its clinical use. For the femur, lateral radiographs demonstrated a consistent relationship between the intercondylar roof line (Blumensaat's line) and the nearly circular profile of the posterior and inferior contour of the lateral femoral condyle. The middle of this circular profile is consistently projected on Blumensaat's line at 66% of its anterior-to-posterior direction. Intraoperative images were used, which showed the aiming drill at the point of entering the lateral femoral condyle. Instead of determining the femoral attachment site relative to Blumensaat's line, we can thus determine its position relative to the center of the circle. Based on intraoperative x-rays, the proposed femoral ACL attachment site can be projected on a line parallel with the Blumensaat's line from the circle center in the posterior direction. Our results indicate that there are consistently identifiable radiographic features on the tibia and femur contours that can be used for fluoroscopic and computer-assisted guidance of ACL graft placement.

Graft isometricity in unitunnel anterior cruciate ligament reconstruction: analysis of influential factors using a radiographic model.

A radiographic model was developed to investigate the influence of three surgical variables on the change in attachment point distance (CAPD) of a hypothetical graft using the unitunnel technique of anterior cruciate ligament (ACL) reconstruction. Using three different femoral target points, we tested the hypothesis that varying the angle of knee flexion between 70 degrees and 110 degrees and varying the tibial starting point over a 4-cm range do not result in a significant variation in CAPD. We also tested the hypothesis that the CAPD from 0 degrees to 135 degrees is greater than the CAPD from 0 degrees to 90 degrees. There was a statistically significant correlation (r = 0.8465, P < 0.0001) between radiographically estimated and isometer-measured values of CAPD. The tibial starting point and the femoral target point were found to affect the CAPD significantly (P < 0.005). A more proximal tibial starting point was associated with a lower CAPD. Both the center of the anatomic femoral attachment of the ACL, and a point 1 mm medial to the junction of the roof and lateral wall of the femoral intercondylar notch and 6 mm anterior to its posterior margin, were associated with lower CAPD values than a target point 5 mm superior and posterior to the center of the femoral ACL attachment. The angle of knee flexion did not significantly affect the CAPD. The CAPD [0 degrees-135 degrees] was significantly greater than the CAPD [0 degree-90 degrees] for all combinations of variables (P < 0.0005).(ABSTRACT TRUNCATED AT 250 WORDS)