Femoral Attachment Of Anterior Cruciate Ligament Research Articles

Comparison of Electrothermal Ablation and Electrolyte Plasmalization Devices Based on the Mechanical Properties of Anterior Cruciate Ligament Femoral Attachment Following Partial Debridement: A Biomechanical Study Using a Porcine Model.

Purpose This study aimed to clarify whether differences in ablation devices used in the knee joint during partial debridement of the proximal end of the femoral attachment of the anterior cruciate ligament (ACL) affect the mechanical properties of the femur-ACL-tibia complex. Methods Electrothermal ablation was generated from Vulcan for the left knees, and radiofrequency ablation was generated from Werewolf Flow 50 Wand for the right knees. The probes were set to the default setting of 120 W and 150 W for Vulcan and Werewolf Flow 50 Wand, respectively. To mimic partial debridement in remnant tissue-preserving (RTP) ACL reconstruction, the bipolar ablation mode and serpentine movements were employed while in contact with the femoral fan-like extension fibers of the ACL. To simulate the arthroscopic environment, the model was immersed in a saline solution. The probes were applied for 60 s, and their biomechanical properties were evaluated. Results A significant difference was observed in the upper yield load between the two groups (Vulcan group, 107.1 ± 93.4 N; Werewolf group, 177.9 ± 108.8 N; P = 0.045). However, no significant differences were noted in linear stiffness (Vulcan group, 47.6 ± 30.9 N/mm; Werewolf group, 50.1 ± 30.5 N/mm; P = 0.85), maximum load (Vulcan group, 276.2 ± 171.8 N; Werewolf group, 397.7 ± 150.8 N; P = 0.26), or elongation at failure (Vulcan group, 6.1 ± 0.9 mm; Werewolf group, 11.6 ± 10.4 mm; P = 0.20) between the two groups. Conclusion The mechanical properties of the ACL after partial ACL femoral attachment debridement for RTP-ACL reconstruction were better when an electrolyte plasmalization device was used. When performing RTP-ACL reconstruction, surgeons must consider that the device used for partial femoral ACL stump debridement may affect the mechanical properties of the ACL remnant tissue. Clinical relevance When performing RTP-ACL reconstruction, surgeons must consider that the device used for partial femoral ACL stump debridement may affect the mechanical properties of the ACL remnant tissue.

GENDER FEATURES OF THE AREAS OF ATTACHMENT OF THE ANTERIOR CRUCIATE LIGAMENT TO THE LATERAL FEMORAL CONDYLE FROM THE POSITION OF SURGICAL ANATOMY

Injury of the anterior cruciate ligament (ACL) remains the most common cause leading to limited knee function and earlier development of gonarthrosis. The results of ACL repair in male and female patients remain heterogeneous. Women have worse results of surgical treatment, as well as higher risks of ACL injuries (from 1,5 to 10 times) when playing sports. It is assumed that the features of the anatomical structure of the knee play the key role in this joint. We have studied 40 unpaired anatomical preparations of the human knee joint obtained from women and men.The morphometry of the distal femoral epiphysis was performed using a digital sliding caliper according to 16 parameters. When examining the areas of femoral ACL attachment, their shape, size, area, and center distance from individual bone structures were assessed. The data obtained were correlated with the type of structure of the knee joint. Were studied the anatomical features characteristic of the "female" type of structure of the knee joint. It was found that the type of structure of the knee joint affects the topography of the femoral attachment area of the ACL, which must be taken into account in anatomical ligament reconstruction.

Anterior cruciate ligament remnant\u2010preserving and re\u2010tensioning reconstruction: a biomechanical comparison study of three different re\u2010tensioning methods in a porcine model

BackgroundWith the developments in the arthroscopic technique, anterior cruciate ligament (ACL) remnant-preserving reconstruction is gradually gaining attention with respect to improving proprioception and enhancing early revascularization of the graft. To evaluate the mechanical pull-out strength of three different methods for remnant-preserving and re-tensioning reconstruction during ACL reconstruction.MethodsTwenty-seven fresh knees from mature pigs were used in this study. Each knee was dissected to isolate the femoral attachment of ACL and cut the attachment. An MTS tensile testing machine with dual-screw fixation clamp with 30° flexion angle was used. The 27 specimens were tested after applying re-tensioning sutures with No. 0 polydioxanone (PDS), using the single stitch (n = 9), loop stitch (n = 9), and triple stitch (n = 9) methods. We measured the mode of failure, defined as (1) ligament failure (longitudinal splitting of the remnant ACL) or (2) suture failure (tearing of the PDS stitch); load-to-failure strength; and stiffness for the three methods. Kruskal-Wallis test and Mann-Whitney U-test were used to compare the variance of load-to-failure strength and stiffness among the three groups.ResultsLigament failure occurred in all cases in the single stitch group and in all but one case in the triple stitch group. Suture failure occurred in all cases in the loop stitch group and in one case in the triple stitch group. The load-to-failure strength was significantly higher with loop stich (91.52 ± 8.19 N) and triple stitch (111.1 ± 18.15 N) than with single stitch (43.79 ± 11.54 N) (p = 0.002). With respect to stiffness, triple stitch (2.50 ± 0.37 N/mm) yielded significantly higher stiffness than the other methods (p = 0.001).ConclusionsThe results suggested that loop stitch or triple stitch would be a better option for increasing the mechanical strength when applying remnant-preserving and re-tensioning reconstruction during ACL reconstruction.

Gender Differences of the ACL Insertion Sites

Background. The modern principles of reconstruction of the anterior cruciate ligament (ACL) and well-known surgical techniques do not take into account the peculiarities of the anatomical structure of the female knee. This happens due to insufficient substantiation that these peculiarities could influence the results of the treatment. The purpose of this study was to obtain new data on the structure of the areas of the ACL attachment, taking into consideration patient’s gender and the surgical anatomy. Material and Methods. 40 unpaired “fresh” anatomical preparations of the human female and male knees were studied. After preparation of the knee joints, the morphometry of the distal femoral epiphysis and the proximal tibial epiphysis was carried out by a digital sliding caliper according to 16 parameters. The shape, size, area, and the distance of the ACL attachment center from individual bone structures were assessed. The obtained data were correlated with the gender type of the knee structure. Results. The distal femoral epiphysis of the “female” type knee joint compared with the “male” type revealed the significant differences (p0.05) in the following parameters: the width of the condyles at the level of the transepicondylar line, the width of the intercondylar fossa, the length and height of the lateral condyle, and the ratio of the condyles width at the level of the transepicondylar line to the height of the lateral condyle. The tibial proximal epiphysis showed the gender differences in the articular surface frontal and sagittal dimensions, the width of the intercondylar eminence and the posterior slope of the tibial epiphysis articular surface. These features determined the different proportions of the female knee structure. The area of the anterior cruciate ligament femoral attachment and its center in the “female” type of structure were located 3 mm distal and 1.5 mm posteriorly (anteriorly and downwardly in arthroscopic imaging). The area of the tibial attachment of the same ligament and its center were localized 2 mm anteriorly in comparison with the “male” type structure. Conclusion. The discovered anatomical differences made it possible to distinguish the “female” and “male” types of the knee structure. The topography of the anterior cruciate ligament attachment areas is gender specific. This should be taken into account in the anatomical reconstruction of the ligament.

Anatomical ACL Reconstruction can Restore the Natural Knee Kinematics than Isometric ACL Reconstruction During the Stance Phase of Walking

The attachment locations of anterior cruciate ligament (ACL) grafts during reconstruction have been reported to influence knee joint function. However, there are controversial opinions on femoral ACL attachment locations for restoring normal knee kinematics. The knee stability and ACL force by different ACL attachment locations could be predicted using the musculoskeletal model simulation. The objectives of this study are to develop a detailed musculoskeletal knee model and to quantify the effect of ACL graft attachment locations on knee kinematics and graft force. Five normal subjects walked at a self-selected speed, and motion data were captured. A detailed knee model including 14 ligaments was developed for dynamics simulation using cadaveric specimen data, which were previously published and are open to public access. The ACL bundles of the model were removed and replaced with ACL grafts to develop anatomical and isometric ACL-reconstructed knee models; the femoral anatomical footprint and isometric locations were used, respectively. After the knee models were embedded in a full-body template model from the AnyBody Managed Model Repository, the full-body musculoskeletal model was simulated using the measured gait data. The isometric reconstruction model had significantly large anterior translation and internal rotation than the intact and anatomical reconstruction model. The average differences between the isometric reconstruction and intact models were 4.5 mm and 3.0° for tibial anterior translation and internal rotation, respectively. The ACL tensional force in the isometric reconstruction model was significantly lower than that in the intact model. Anatomical reconstruction could closely restore the normal knee kinematics.

Behind-remnant approach for anatomic anterior cruciate ligament reconstruction

A newly proposed femoral tunnel creation concept, a behind-remnant (BR) approach, for remnant-preserving double-bundle (DB) anterior cruciate ligament (ACL) reconstruction, was introduced. In this technique, femoral tunnels are created based on the arthroscopic observation from behind the ACL remnant, using the remnant fold at the ACL femoral attachment and posterior cartilage margin as landmarks, without any removal of the remnant tissue. Graft tension changes and femoral tunnel position of the anteromedial bundle (AMB) and posterolateral bundle (PLB) in the BR approach (BR group, 23 patients) were compared with those in the control group (25 patients). Two-year clinical results in 48 patients who had DB ACL reconstruction using BR approach were evaluated. During passive knee movement, the control group indicated reciprocal tension pattern between the AMB and PLB. The PLB generally showed greater tension in extension than the AMB. The BR group indicated equivalent tension pattern between the AMB and PLB. The AM tunnel position was significantly more posterior in the BR group with the smaller variances than in the control group. During 2-year follow-up, there was 1 graft tear of the reconstructed ACL. Average KT measurements improved from 6.1 mm preoperatively to 0.6 mm. Lachman test became negative in all cases. Pivot shift result was also improved, although 6 cases had residual pivot shift test. Average Lysholm score was improved from 79 preoperatively to 98, and average time required to return to athletic activities was 8 months. The BR approach made femoral tunnel creation possible with better reproducibility. More posterior tunnel creation using BR approach indicated similar tension pattern between the AMB and PLB. Short-term clinical results after remnant-preserving DB ACL reconstruction using BR approach were satisfactory in both subjective and objective findings.

DEPENDENCE OF THE OUTCOMES OF ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION ON THE TUNNEL POSITIONING

Purpose of study: based on the analysis of clinical and radiation data to determine the most favorable positioning of the bone tunnels at different techniques of anterior cruciate ligament (ACL) reconstruction.Study design: retrospective analysis.Patients and methods. Face-to-face and a remote examination was performed in 202 patients at terms from 1.5 to 5 years after primary ACL autoplasty using the graft from the popliteal muscle tendons. All patients were divided into 3 groups depending on the technique of the bone tunnels formation. The patients from the 1stgroup (n=109) were operated on using transtibial technique, from the 2nd(n=52) and 3rd(n=41) groups – using anteromedial technique with the positioning of the femoral tunnel in the central and anteromedial part of ACL attachment, respectively. Bone tunnels positioning was determined using CT with 3D reconstruction. Subjective evaluation was performed by IKDS-2000, KOOS and Lysholm knee score. To assess the tibiofemoral dislocation the anterior drawer, Lachman and pivot shift tests as well as arthrometry (comparison with the healthy side) were performed.Results.In patients from group 1 the tibial tunnel was positioned in the plane of either central or posterolateral part of ACL attachment. In groups 2 and 3 the tunnel was positioned closer to the anteromedial part. In the majority of patients form group 1 the femoral tunnel was positioned in the zone or slightly forwards of the anteromedial part of ACL femoral attachment, in group 2 – in the plane of central or posterolateral part, in group 3 – in the anteromedial part. In patients from the 1st and 2nd groups the subjective evaluation by IKDS-2000, KOOS and Lysholm knee score was comparable and much higher in the 3rdgroup (p<0.05). Objective evaluation showed positive manual tests results in 47 patients (62%) from the 1st group, 19 patients (51%) – 2ndgroup and 4 patients (11%) – 3rdgroup. Arthrometry showed the increase of anteroposterior tibiofemoral dislocation by 3.4±2.6 mm in the 1st group, 3.1±2.7 mm in the 2nd group and 1.2±1.4 mm. Statistical analysis did not reveal significant difference in knee stability between the patients from the 1stand 2ndgroups.Conclusion.Positioning of the femoral tunnel in the plane of anteromedial part of ACL attachment ensures better surgical treatment functional results. In anteromedial technique the use of posterosuperior contour of the lateral femoral condyle as a reference point enables to improve the accuracy of femoral tunnel positioning as well as to minimize the error risk at intraoperative marking.

Dependence of the outcomes of anterior cruciate ligament reconstruction on the tunnel positioning

Purpose of study: based on the analysis of clinical and radiation data to determine the most favorable positioning of the bone tunnels at different techniques of anterior cruciate ligament (ACL) reconstruction. Study design: retrospective analysis. Patients and methods. Face-to-face and a remote examination was performed in 202 patients at terms from 1.5 to 5 years after primary ACL autoplasty using the graft from the popliteal muscle tendons. All patients were divided into 3 groups depending on the technique of the bone tunnels formation. The patients from the 1st group (n=109) were operated on using transtibial technique, from the 2nd (n=52) and 3rd (n=41) groups - using anteromedial technique with the positioning of the femoral tunnel in the central and anteromedial part of ACL attachment, respectively. Bone tunnels positioning was determined using CT with 3D reconstruction. Subjective evaluation was performed by IKDS-2000, KOOS and Lysholm knee score. To assess the tibiofemoral dislocation the anterior drawer, Lachman and pivot shift tests as well as arthrometry (comparison with the healthy side) were performed. Results. In patients from group 1 the tibial tunnel was positioned in the plane of either central or posterolateral part of ACL attachment. In groups 2 and 3 the tunnel was positioned closer to the anteromedial part. In the majority of patients form group 1 the femoral tunnel was positioned in the zone or slightly forwards of the anteromedial part of ACL femoral attachment, in group 2 - in the plane of central or posterolateral part, in group 3 - in the anteromedial part. In patients from the 1st and 2nd groups the subjective evaluation by IKDS-2000, KOOS and Lysholm knee score was comparable and much higher in the 3rd group (p

A study on associated injuries of anterior cruciate ligament tear

Introduction: Over the last decade, reconstruction of the anterior cruciate ligament (ACL) has evolved from a surgical technique in which the objectives were ‘isometric’ femoral tunnel placement and avoidance of inter-condylar notch roof impingement, towards an ‘anatomic’ surgical technique which attempts to restore the native ACL. Achieving the goals of isometric ACL graft placement and avoidance of roof impingement often resulted in the ACL femoral tunnel extending into the roof of the notch, outside of the native ACL femoral attachment site and the tibial tunnel being positioned in the posterior half of the native ACL tibial attachment site. Methodology: All patients admitted with clinico-radiological diagnosis of ACL tear with h/o injury (trauma) who met the inclusion criteria. This was a Prospective observational study with the minimum follow up 12 months. The sample size was 30. Results: A Total of 90% (27 cases) (n=27) patients had associated injuries usually the meniscal tear. Isolated medial meniscal tear were found in 33.3% (10 cases) (n=10) while isolated lateral meniscus tear were found in 33.3% (10 patients) (n=10) of cases. Combined medial and lateral meniscus tear were found in 23%% (7 cases) (n=7). Conclusion: Chondral changes were found in 30% (9 cases) (n=9) MCL, LCL and posterior cruciate ligament tear was found in none.

Comparison of Anterior Cruciate Ligament Graft Isometry between Paired Femoral and Tibial Tunnels.

Accurate tunnel placement is important for a successful anterior cruciate ligament (ACL) reconstruction. Controversy exists concerning the preferred method of femoral tunnel preparation, with proponents of both medial portal and transtibial drilling techniques. Current ACL literature suggests that placement of the femoral ACL attachment site posterior or "low" in the ACL footprint leads to more anatomically correct ACL mechanics and better rotational control. There is limited literature focusing on ACL graft displacement through knee range of motion based on specific paired placement of femoral and tibial tunnels. Our purpose was to assess ACL isometry between multiple combinations of femoral and tibial tunnels. We hypothesized that placement of the graft at the posterior aspect of the ACL footprint on the femur would be significantly less isometric and lead to more graft displacement as compared with central or anterior placement. The ACL of matched pairs of cadaveric knees was arthroscopically debrided while leaving the soft tissue footprint on the femur and tibia intact. One knee from each pair underwent notchplasty. In all knees, three femoral and three tibial tunnels were created at the anterior, central, and posterior aspects of the ACL footprint. A suture was passed through each tunnel combination (nine potential pairs), and the change in isometry was measured throughout full knee range of motion. Placement of the femoral tunnel along the posterior aspect of the ACL footprint was less isometric compared with a central or anterior position in the femoral footprint. Placement of a posterior tibial tunnel also led to decreased isometry, but tibial tunnel placement affected isometry to a lesser extent than femoral tunnel placement. The combination of a posterior femoral and posterior tibial tunnel resulted in greater than 1 cm of graft excursion from full flexion to extension. Placement of ACL tunnels at anisometric sites may adversely affect the mechanical properties and behavior of the ACL graft, resulting in either graft laxity in flexion or overconstraint and loss of extension.

Bony Morphology: Comparative Anatomy and its Importance for the Anterior Cruciate Ligament

Bone morphology is related to static and dynamic parameters during anterior cruciate ligament (ACL) kinematics and can affect injury mechanism patterns, gait analysis, biomechanical properties, and surgical references for ligament reconstructions. It does not only depend on mechanical factors but also reflects a developmental program with many other factor involved, including nutrition and hormones, especially those involved in the calcium metabolism. Although Wolff׳s law continues to be a dominant paradigm in Orthopaedics, in the past 15 years enormous advances have been made that have improved our understanding of how individual bones achieve their internal and external structure. Transition from the quadrupedal mode of locomotion to bipedalism compelled changes in the femur morphology and the modern human knee has an extensive history of modifications produced by natural selection acting on its function in habitually upright walking and running. The human ACL is a band-like structure of dense connective tissues that binds the femur to the tibia. The femoral ACL attachment is located on the posterior aspect of the medial surface of the lateral femoral condyle and is composed of both direct and indirect fibers; the central part of the insertion is constructed in the manner described by the classical 4-phase architecture (direct insertion), whereas the posterior margin of the insertion is composed of a 2-phase architecture more typical of indirect insertions. The knowledge of anatomy, comparative anatomy, evolution, and natural selection allows us to have a more profound understanding of the interaction between form and function; after all, as Theodosius Dobzhansky has stated, Nothing in biology makes sense except in the light of Evolution.

Biomechanical comparison of graft structures in anterior cruciate ligament reconstruction

PurposeDouble-bundle (DB) anterior cruciate ligament (ACL) reconstruction may offer kinematic restoration superior to anatomic single bundle (SB), but it remains technically challenging. The femoral attachment site has the most effect on ACL graft isometry, so a simplified three-socket (3S) construct which still uses two sockets to cover the femoral ACL attachment is attractive. It was hypothesised that ACL reconstruction using three- and four-socket techniques would more closely restore native knee kinematics compared to anatomic two-socket (SB) surgery.MethodsNine cadaveric knees were used to evaluate the kinematics of ACL-intact, ACL-deficient, anatomic SB, three-socket, and DB arthroscopic ACL reconstructions. Suspensory fixation was used, and grafts were tensioned to match the anterior draw of the intact knee at 20°. A six-degree-of-freedom robotic system measured knee laxity under 90 N anterior tibial force and rotational laxity under 5 N-m torque. Combined moments were applied to simulate the pivot-shift subluxation: 4 N-m internal rotation and 8 N-m valgus.ResultsSignificant differences between reconstructions were not found during anterior tibial loading, apart from SB being more lax than DB at 60° flexion. All reconstructions produced comparable laxity to the intact state, apart from SB at 60°. Significant differences between reconstructions were not found at any flexion angle during tibial internal/external applied torques. Under combined loading, DB produced significantly less laxity than SB constructs apart from anterior tibial translation at 0° and internal rotation at 45°. 3S and DB were comparable to the native knee throughout.ConclusionAlthough 3S restored laxities to a similar extent to DB, significant superiority over SB surgery was not observed. Although statistically significant differences were found between SB and DB surgery during anterior tibial and simulated pivot-shift loading, both remained similar to the native knee. The clinical relevance is that this study did not support an ACL graft construct more complex than an anatomic single bundle.

Height and Depth Guidelines for Anatomic Femoral Tunnels in Anterior Cruciate Ligament Reconstruction: A Cadaveric Study

To develop guidelines for femoral tunnel placement based on height and depth on the lateral wall of the notch and to apply these guidelines arthroscopically to show tunnel placements within the anterior cruciate ligament (ACL) femoral insertion site. Twelve cadaveric knees were dissected to define the centers of the femoral ACL attachment and its anteromedial (AM) and posterolateral (PL) bundles. In 90° of flexion, the height and depth of each center were determined relative to the low point on the lateral intercondylar notch. Radiographic grid measurements were made to validate these measurements. Subsequently, the measurement guidelines were applied arthroscopically in 10 new cadaveric knees to evaluate their accuracy for an anatomic single-bundle femoral tunnel. Interobserver reliability analysis was evaluated with the intraclass correlation coefficient. In 90° of flexion, the height of the ACL center was 8.7 ± 0.6mm from the low point of the lateral notch; PL center, 7.2 ± 1.2mm; and AM center, 9.6 ± 1.1mm. Relative to the low point, the ACL center was 1.7 ± 1.7mm posterior, the PL center was 3.4 ± 1.5mm anterior, and the AM center was 4.9 ± 1.7mm posterior (intraclass correlation coefficient, 0.859). Radiographic grid measurements were consistent with the direct measurements. Application of the guidelines arthroscopically with or without the assistance of a 7-mm offset aimer placed all guide pins for tunnels within the femoral ACL footprint, with 90% within 4mm of the ACL center. This study showed in cadaveric knees in 90° of flexion that the center of the ACL can be located on the lateral notch at a height of 8.7 ± 0.6mm from the lowest point and anterior 11.5 ± 1.3mm from the deepest point. How anatomic tunnels can be placed using these measurements was also shown in cadaveric knees. An anatomic femoral tunnel for ACL reconstruction can be placed using height and depth guidelines.

Finite element study on the anatomic transtibial technique for single-bundle anterior cruciate ligament reconstruction.

The anatomic transtibial (TT) technique is proposed as a new approach for single-bundle anterior cruciate ligament (ACL) reconstruction. Geometric models of the anatomic TT and anteromedial (AM) portal techniques were fabricated with a reconstructed knee joint model and virtual surgical operations. Grafts of 7 mm diameter were modeled and inserted into tunnels drilled in each model. In the models, the shape of the graft between the femur and the tibia, the lengths of the bone tunnels, and the femoral graft bending angles were evaluated. To evaluate the biomechanical effects of both techniques on the grafts, the contact pressures and maximum principal stresses in the grafts were calculated using the finite element method. The anatomic TT technique placed the femoral tunnel to the anatomic position of the native ACL femoral attachment site. In addition, it decreased the peak contact pressure and the maximum principal stress at the full extension position of the graft compared with the AM portal technique. The anatomic TT technique may be regarded as a superior surgical technique compared with the conventional TT and AM portal techniques. Because of the easy surgical operation involved, the technique decreases the operation time for ACL reconstruction and it provides a deformation behavior of grafts similar to that in the native ACL in a knee joint. With its few side effects, the anatomic TT technique may considerably help patients.

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.

The Role of Fibers in the Femoral Attachment of the Anterior Cruciate Ligament in Resisting Tibial Displacement

PurposeThe purpose was to clarify the load-bearing functions of the fibers of the femoral anterior cruciate ligament (ACL) attachment in resisting tibial anterior drawer and rotation.MethodsA sequential cutting study was performed on 8 fresh-frozen human knees. The femoral attachment of the ACL was divided into a central area that had dense fibers inserting directly into the femur and anterior and posterior fan-like extension areas. The ACL fibers were cut sequentially from the bone: the posterior fan-like area in 2 stages, the central dense area in 4 stages, and then the anterior fan-like area in 2 stages. Each knee was mounted in a robotic joint testing system that applied tibial anteroposterior 6-mm translations and 10° or 15° of internal rotation at 0° to 90° of flexion. The reduction of restraining force or moment was measured after each cut.ResultsThe central area resisted 82% to 90% of the anterior drawer force; the anterior fan-like area, 2% to 3%; and the posterior fan-like area, 11% to 15%. Among the 4 central areas, most load was carried close to the roof of the intercondylar notch: the anteromedial bundle resisted 66% to 84% of the force and the posterolateral bundle resisted 16% to 9% from 0° to 90° of flexion. There was no clear pattern for tibial internal rotation, with the load shared among the posterodistal and central areas near extension and mostly the central areas in flexion.ConclusionsUnder the experimental conditions described, 66% to 84% of the resistance to tibial anterior drawer arose from the ACL fibers at the central-proximal area of the femoral attachment, corresponding to the anteromedial bundle; the fan-like extension fibers contributed very little. This work did not support moving a single-bundle ACL graft to the side wall of the notch or attempting to cover the whole attachment area if the intention was to mimic how the natural ACL resists tibial displacements.Clinical RelevanceThere is ongoing debate about how best to reconstruct the ACL to restore normal knee function, including where is the best place for ACL graft tunnels. This study found that the most important area on the femur, in terms of resisting displacement of the tibia, was in the central-anterior part of the femoral ACL attachment, near the roof of the intercondylar notch. The testing protocol did not lead to data that would support using a large ACL graft tunnel that attempts to cover the whole natural femoral attachment area.

Assessing the accuracy of femoral tunnel placement in anatomic ACL reconstruction (913.13)

Current trends in Anterior Cruciate Ligament (ACL) Reconstruction favor anatomic positioning of ACL attachment sites. Surgical inaccuracy in femoral tunnel positioning can lead to potential early graft failure and early‐onset osteoarthritis.The purpose of this study was to evaluate accuracy of femoral tunnel positioning by orthopedic surgeons using five ACL femoral guides.Using a human cadaveric femur, the mathematical center of the ACL femoral attachment was determined to be the anatomically ideal location for femoral tunnel placement. Five orthopedic surgeons performed arthroscopic femoral tunnel pin placement on identical artificial femurs using 5 different femoral guides (ConMedTM Linvatec Offset &amp; BullseyeTM, Arthrex® Transportal, Stryker® VersiTomic®, Smith&amp;Nephew CLANCYTM). Tunnel placement was compared to the ideal position using virtual Computer Tomography. A total of 125 femurs were used.The Stryker® guide had greatest accuracy (distance from ideal footprint) at 3.9mm, and the most optimal tunnel length at 33.4mm. Only 8/125 iterations were within our set acceptable limit of 2mm from the ideal footprint.Tremendous variability of femoral tunnel positioning was observed with each guide. Only 6.4% of trials fell within our acceptable limit. Complimentary research is needed in cadavers and humans to fully elucidate anatomic accuracy and applicability to the operating room.

Reliability of Estimates of ACL Attachment Locations in 3-Dimensional Knee Reconstruction Based on Routine Clinical MRI in Pediatric Patients

Background: Current techniques of anterior cruciate ligament (ACL) reconstruction focus on the placement of femoral and tibial tunnels at anatomic ACL attachments, which can be difficult to identify intraoperatively. Purpose: To determine whether the 3-dimensional (3D) center of ACL attachments can be reliably detected from routine magnetic resonance imaging (MRI) in patients with intact ACLs and whether the reliability of this technique changes if the ACL is torn. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: A computer technique was developed in which users identify points along ACL attachments on routine clinical MRI of preoperative knees. These attachments are then displayed on a 3D MRI reconstruction, which can be used as a visual guide for the surgeon during arthroscopic surgery. Thirty-seven pediatric patients (age range, 10-17 years) with ACL tears and 37 controls with intact ACLs were examined. Two blinded observers identified cruciate ligament attachments on routine clinical 1.5-T MRI of knees. From the resulting 3D model, the location of the center of each ligament attachment site and its area were calculated and reliability assessed. Results: Mean interobserver variation of the centers of ACL attachments for the intact versus torn ACL was 1.7 ± 0.9 mm versus 1.8 ± 1.1 mm (femoral) and 1.4 ± 0.9 mm versus 1.7 ± 1.0 mm (tibial), respectively (P > .05). The 95% confidence interval for the center location was at most 4 mm. The identified ACL attachment areas were more variable, with interobserver reliability ranging from fair to excellent by the intraclass correlation coefficient. Overlap of ligament areas between observers for the intact versus torn ACL was 70% ± 15% versus 73% ± 12% (femoral) and 79% ± 9% versus 78% ± 10% (tibial), respectively (P > .05). In all cases, intraobserver reliability was superior to interobserver reliability. Conclusion: The 3D locations of ACL tibial and femoral attachment centers were identified from routine clinical MRI with variability averaging less than 2 mm between 2 observers. The margin of error was at most 4 mm, representing the thickness of a single axial MRI slice, whether the ACL was intact or torn. Remnant tissue at attachments allows a reliable assessment even of torn ligaments. Identification of the ligament attachment areas was more user dependent than was identification of the attachment centers.

Analysis of anatomic positioning in computer-assisted and conventional anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) reconstruction should be anatomic while achieving favorable anisometric behavior to avoid impingement with the femoral notch. Computerization enables these biomechanical conditions to be optimally fulfilled; but what of anatomic positioning? The present study compared the positioning of tibial and femoral tunnels, drilled using either a conventional ACL guide or a navigation system, using the anatomic foot-print areas of the native ACL. This cadaver study used computerized recording to compare tibial and femoral ACL attachment areas to the positioning of tunnels created either conventionally or under computer-guided navigation. Computer guidance enabled the tibial and femoral tunnels to be systematically positioned within the anatomic area and, as regards the tibial area, within the anterior third near to the medial tibial spine, without femoral notch impingement. Anisometry was in all cases favorable, at a mean 3.3 ± 0.7 mm; using a conventional guide, anisometry was favorable in only 50% of cases, at a mean 5.4 ± 1.2 mm. Computer-guided navigation ensured implant positioning within the so-called anatomometric area of the native ACL attachment, avoiding impingement with the femoral notch. Level 2.

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.