Can Surgeons Identify ACL Femoral Ridges Landmark and Optimal Tunnel Position? A 3D Model Study.
ABSTRACT: Purpose:To examine the ability of surgeons to identify the osseous landmarks associated with the femoral anterior cruciate ligament (ACL) footprint and locate optimal tunnel placement on 3-dimensional (3D) printed models compared with intraoperative placement. Methods:Twelve sports fellowship-trained orthopaedic surgeons were asked to identify a femoral landmark and an ACL footprint on 10 different 3D printed knees. The 3D models were made based on 20 real patients with different anatomical morphology who later received ACL reconstructive surgery using independent drilling. ImageJ software was used to quantify the measurements, which were then analyzed using descriptive statistics. Results:Overall, none of the surgeons were able to consistently identify the junction of the bony ridges. The mean error per participant ranged from 2.81 to 7.34 mm in the proximal direction (P = 3.30e-05) and from 2.42 to 8.05 mm in the posterior direction (P =4.88e-12). None of the surgeons were able to appropriately identify the center of the femoral footprint on the anatomic 3D models. The difference between the center of the footprint surgeons identified on the 3D model and the tunnel graft location in surgery was significantly different (P = .0046). On average, the magnitude of the error when the surgeons performed the actual surgery was 3.72 ± 2.43 mm, whereas on the 3D models it was 5.82 ± 1.97 mm. Conclusions:Experienced sports fellowship-trained orthopaedic surgeons were unable to correctly identify the junction of the intercondylar and bifurcate ridges and the native ACL footprint on 3D models. Operatively placed tunnels were more accurate implying that looking either through a scope or soft-tissue landmarks play a significant role in surgeons ACL footprint localization. Clinical Relevance:The graft position for ACL reconstruction plays an important role on the kinematics of the knee. This paper shows that soft tissue landmarks are needed to provide reliable reference points for reconstruction.
Project description:Purpose:The purpose of this study was to use 3-dimensional magnetic resonance imaging modeling of the skeletally immature knee to help characterize safe and reproducible tunnel positions, diameters, lengths, trajectories, and distances from anatomic landmarks and the physeal and articular cartilage for physeal-sparing anterior cruciate ligament (ACL) reconstructive surgery. Methods:Magnetic resonance imaging from 19 skeletally immature knees with normal anatomy were gathered. The 3-dimensional models were created, and the relevant anatomic structures were identified. Cylinders simulating tunnel length, diameter and trajectory were superimposed onto the models, and descriptive measurements were performed. Results:A safe position for the creation of an 8 mm diameter femoral tunnel was described in the lateral femoral condyle. The femoral tunnel length averaged 25.5 ± 2.6 mm. The bony entry point was located 3.8 ± 2.4 mm proximally and 12.7 ± 2.2 mm posteriorly to the lateral epicondyle. The shortest distance from the tunnel edge to the physis and femoral articular cartilage was 2.8 ± 0.7 mm and 3.7 ± 0.9 mm, respectively. The safe position for an 8 mm diameter tibial tunnel was also identified and described in the proximal tibia. The epiphyseal tibial tunnel length from the ACL footprint to the physis averaged 15.5 ± 1.6 mm. The proximal tibial epiphysis was found to accommodate a tibial crosspin measuring 63.5 ± 5.9 mm in length and 8.2 ± 1.5 mm in diameter without disrupting the physis or articular cartilage. Conclusions:Three-dimensional modeling created from magnetic resonance imaging can help define important anatomic relationships for physeal-sparing ACL reconstructive surgery in skeletally immature knees and may assist in reducing the risk of injury to local anatomic structures. Clinical Relevance:Knowledge of the anatomic relationships in skeletally immature knees serves as a valuable reference for surgeons performing physeal-sparing ACL reconstruction surgery.
Project description:Although the transtibial (TT) technique for single-bundle (SB) arthroscopic anterior cruciate ligament (ACL) reconstruction has been widely used, surgeons often disadvantageously create the femoral bone tunnel at the arthroscopically noon position, which is alleged the “ACL isometric point,” when the femoral bone tunnel could be created behind the resident’s ridge with TT-SB ACL reconstruction by paying attention to the location of the tibial tunnel inlet and the angle of tibial tunnel. This alternative approach preserves ACL remnant tissue, which might contribute to better postoperative remodeling and regeneration of proprioceptive mechanoreceptors. This technique reduces surgical invasiveness and can enhance postoperative graft remodeling and proprioceptive recovery. To successfully use the devices required for this procedure, surgeons must understand the proper techniques. Hence, this technical note aims to demonstrate TT-SB ACL reconstruction with remnant tissue preservation. Technique Video Video 1 Anterior cruciate ligament (ACL) reconstruction is carried out under regional or general anesthesia without a pneumatic tourniquet. The patient is placed in a supine position with the operative knee held in the leg drop position at 90° flexion. Standard anterolateral and anteromedial portals are made. After routine arthroscopic observation, the ACL remnant tissue is pulled with a probe and confirmed to be Crain type 3. The proximal end of the remnant femoral stump located behind the resident’s ridge is minimally debrided using a shaver, and a thermal device is used to create the femoral bone tunnel. During this procedure, careful attention should be made to the ACL remnant tissue so that it is not injured and to preserve the continuity and maximize the amount of ACL remnant tissue. Anatomic insertion of the femoral anteromedial bundle (AMB) is identified behind the resident’s ridge via the anteromedial portal. Then, a longitudinal slit is made at the center of the tibial ACL remnant tissue, into which the tibial ACL guide is inserted. The center of the tibial bone tunnel is placed at the AMB footprint from the lateral to the medial tibial spine. The center of the AMB insertion is defined according to 3 surrounding landmarks, namely, the anterior ridge, lateral groove, and intertubercular fossa, and bony prominences corresponding to the ACL tibial footprint are identified. The coronal angle relative to the tibial axis averages 25.5°, and the sagittal angle relative to the tibial axis was averages 52.3°. Then, a tibial tunnel with a diameter of 8.5 to 9 mm is made. The femoral bone tunnel insert is positioned inferior to the “over-the-top” position. The 6-mm femoral aimer is inserted through the tibial tunnel to prevent posterior wall blowout with varus and internal rotation of the tibia, thus resulting in a figure-four position. Hence, the femoral bone tunnel is created lower and deeper, thus placing it behind the resident’s ridge. The 2.4-mm guide pin insertion point is confirmed via anteromedial portal considering the location behind the resident’s ridge. Then, 4.5-mm arthroscopic drilling accompanied by an 8-mm over drilling is performed to create a socket-shaped tunnel. When the femoral tunnel cannot be created behind the resident’s ridge, surgeons should consider creating a femoral tunnel using the outside-in technique or transportal technique. The length of the femoral bone tunnel is measured using a depth gage and the length of suspensory fixation device is calculated. A hamstring graft is introduced into the joint cavity through the tibial tunnel and ACL remnant tissue and then placed in the femoral socket.
Project description:Purpose:To assess intra-articular tunnel aperture positioning after primary anterior cruciate ligament (ACL) reconstruction with either the reference standard method or the intercondylar area method in a single center using 3-dimensional (3D) computed tomography (CT) scans and to evaluate the intra-articular position of the tibial tunnel relative to the ACL footprint. Methods:3D CT scans were performed after 120 single-bundle primary ACL reconstruction cases. The center of the tibial tunnel aperture and the center of the ACL footprint were referenced on axial views of the tibial plateau in the anteroposterior (AP) and mediolateral (ML) planes according to a centimetric grid system including the whole plateau (reference standard). This was compared with a grid system based on intercondylar area bony anatomy. The posterior aspect of intertubercular fossa, anterior aspect of the tibial plateau, medial intercondylar ridge, and crossing point between lateral intercondylar ridge and posterior margin were used as landmarks to define the grid. Results:According to the reference standard method, the center of the tibial tunnel aperture was positioned 0.57 ± 2.62 mm more posterior and 0.67 ± 1.55 mm more medial than the center of the footprint. According to the intercondylar area method, the center of the tibial tunnel aperture was positioned 1.32 ± 2.74 mm more posterior and 0.66 ± 1.56 mm more medial than the center of the footprint. The position difference between the center of the tunnel aperture and the center of the footprint were statistically correlated for both grids, with r = -0.887, P < .001 for AP positioning and r = 0.615, P < .001 for ML positioning. Conclusion:This intercondylar area method using arthroscopic landmarks can be used to assess tunnel placement on 3D CT scans after ACL reconstruction. Level of Evidence:III, retrospective comparative study.
Project description:<h4>Purpose</h4>Recently, the configuration of the anterior cruciate ligament (ACL) from its direct femoral insertion to midsubstance was found to be flat. This might have an important impact for anatomical ACL reconstruction. The purpose of this anatomical study was to evaluate the macroscopic appearance of the ACL from femoral to midsubstance.<h4>Methods</h4>The ACL was dissected in 111 human fresh frozen cadaver knees from its femoral insertion to midsubstance, and the shape was described. The anatomical findings were documented on digital photographs and on video. Thirty knees were sent for computed tomography (CT), magnetic resonance imaging (MRI) and histology of the femoral ACL insertion.<h4>Results</h4>Two millimetres from its direct femoral insertion, the ACL fibres formed a flat ribbon in all dissected knees without a clear separation between AM and PL bundles. The ribbon was in exact continuity of the posterior femoral cortex. The width of the ribbon was between 11.43 and 16.18 mm and the thickness of the ACL was only 2.54-3.38 mm. 3D CT, MRI and the histological examination confirmed above findings.<h4>Conclusion</h4>This is a detailed anatomical study describing the ribbon-like structure of the ACL from its femoral insertion to midsubstance. A key point was to carefully remove the surface fibrous membrane of the ACL. A total of 2-3 mm from its bony femoral insertion, the ACL formed a flat ribbon without a clear separation between AM and PL bundles. The ribbon was in exact continuity of the posterior femoral cortex. The findings of a flat ligament may change the future approach to femoral ACL footprint and midsubstance ACL reconstruction and to graft selection.
Project description:Pediatric anterior cruciate ligament (ACL) tears present a technical dilemma for orthopaedic surgeons. Multiple surgical techniques have been described to protect the distal femoral and proximal tibial physes. We present an ACL reconstruction technique performed on a 12-year-old girl with open physes who sustained an ACL tear after a noncontact twisting injury while playing soccer. A hamstring autograft reconstruction was performed by use of a posteromedial portal to drill the femoral tunnel in an all-epiphyseal fashion at the anatomic footprint of the native ACL. This case provides a new surgical technique to achieve anatomic fixation for ACL reconstruction in a skeletally immature individual using a posteromedial portal to drill a physeal-sparing lateral femoral tunnel for anatomic ACL reconstruction. This advancement may make drilling the femoral tunnel less technically challenging compared with other proposed methods while maintaining the lateral wall of the distal femur.
Project description:A double-bundle anterior cruciate ligament (ACL) reconstruction associated with an anterolateral ligament (ALL) reconstructions is performed. The semitendinosus and gracilis are harvested. At knee maximum flexion, the anteromedial (AM) femoral tunnel is performed in the AM footprint area. Through the anterolateral portal, the tip of the outside-in femoral guide is placed in the posterolateral footprint area. The guide sleeve is pushed onto the lateral femoral cortex at the ALL attachment. At 110° knee flexion, the posterolateral-ALL tunnel is performed. The tibial ACL tunnel is performed as usual. The tibial guide is placed between the ALL tibial attachment and the tibial ACL tunnel entrance to perform the ALL tibial tunnel. The gracilis graft is introduced from caudal to cranial, achieving fixation with a 6-mm diameter screw (outside-in). The AM femoral fixation is achieved with a suspension device. ACL tibial graft fixation is achieved with a screw. Afterward, the gracilis is passed under the fascia lata to the tibial entry point. A 6-mm diameter screw is placed from the external cortex into the tibial ALL tunnel. The biomechanical advantage of the double-bundle ACL reconstruction with the biomechanical advantage of the ALL anatomic reconstruction is achieved.
Project description:<h4>Background</h4>Anterior cruciate ligament (ACL) rupture is the most common ligament injury treated surgically by orthopaedic surgeons. The gold standard for the treatment of the majority of primary ACL tears is ACL reconstruction. However, novel methods of repair, such as bridge-enhanced ACL repair (BEAR), are currently being investigated as alternatives to reconstruction. To assess patients for midsubstance repair suitability, clarify the prognostic implications of injury location and damage, and evaluate the results of a repair technique, it is important to have a baseline classification system or grading scale that is reproducible across surgeons, particularly for multicenter collaboration. Currently, no such system or scale exists.<h4>Purpose</h4>To develop an arthroscopic ACL tear classification system and to evaluate its interobserver reliability.<h4>Study design</h4>Cohort study (diagnosis); Level of evidence, 3.<h4>Methods</h4>Eleven fellowship-trained orthopaedic surgeon investigators reviewed 75 video clips containing arthroscopic evaluation of a torn ACL and then completed the 6-question ACL Pathology Evaluation Form. Agreement statistics including exact agreement, Fleiss ?, Gwet agreement coefficient 1 (AC1), and Gwet AC2 were then calculated to assess interobserver reliability.<h4>Results</h4>In aggregate, the multiple assessments of observer reproducibility revealed that surgeon participants in this study, when evaluating the same injury, agreed roughly 80% of the time on whether (1) at least 50% of the tibial footprint remained, (2) the remaining tibial stump was ?10 mm, and (3) the injury was therefore reparable using the BEAR procedure. Participants also agreed roughly 60% of the time on exactly how many suturable bundles were available. These characteristics are believed to be most important, among those studied, in determining whether a torn ACL is amenable to midsubstance repair.<h4>Conclusion</h4>This study is the first of its kind to demonstrate the interobserver reliability of arthroscopic classification of ACL tears. We have demonstrated that this classification system, though not ideally reproducible, is reliable enough across surgeons at multiple institutions for use in multicenter studies.<h4>Registration</h4>NCT03776162 (ClinicalTrials.gov identifier).
Project description: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.
Project description:<h4>Background</h4>In an attempt to improve the accuracy and reproducibility of tunnel positioning, radiographs are being analyzed in an attempt to recreate the native anatomy of the ACL. Understanding the native ACL radiographic anatomy is an essential prerequisite to understand the relevance of postoperative tunnel position.<h4>Questions/purposes</h4>We performed a systematic review of the literature to delineate the radiographic location of the native ACL femoral and tibial footprints.<h4>Methods</h4>A search was performed in March 2014 in PubMed, the Cochrane Collaboration Library, and EMBASE to identify all studies that evaluated the native anterior cruciate ligament (ACL) anatomy on radiographs. Various measurement methods were used in each study, and averages were obtained of the data from studies with the same measurement methods.<h4>Results</h4>Fifteen papers were identified (which included data on 177 femora and 207 tibiae in total). Evaluation of the femoral footprint using the quadrant method on lateral knee radiographs showed that the average percent distance location of the anteromedial (AM) bundle and posterolateral (PL) bundle was 22.8% (95% confidence interval (CI) 16.59-28.90) and 32.5% (95% CI 27.71-37.26) from the posterior condyle, respectively, and 23.2% (95% CI 19.52-26.94) and 50.0% (95% CI 46.16-53.76) from Blumensaat's line, respectively. Using the Amis and Jacob method, the tibial footprint on the lateral knee radiograph average percent distances was 35.1% (95% CI 34.46-35.72) for the center of the AM bundle and 47.3% (95% CI 41.69-52.95) for the center of the PL bundle of the ACL. The femoral and tibial ACL footprints on the anteroposterior (AP) views of the knee were not well delineated by these studies.<h4>Conclusion</h4>The information presented in this systematic review offers surgeons another important tool for accurate ACL footprint identification.
Project description:Accurate positioning of the femoral tunnel in the native femoral anterior cruciate ligament (ACL) footprint requires drilling through an accessory medial portal (AMP). The AMP is located far medial and at a low level. Despite the benefits of drilling through the AMP, it is possible that the drill bit head will injure the articular cartilage of the medial femoral condyle as it slides along the guide pin to the femoral insertion of the ACL. Because more surgeons are now performing anatomic ACL reconstructions and shifting from transtibial drilling toward transportal drilling, the risk of this injury might be increasing, especially during the beginning of their learning curve. To avoid such injury, a bio-interference screw sheath is used. It is inserted through the AMP over the guide pin until it reaches near the medial wall of the lateral femoral condyle. The drill bit is inserted over the guide pin and through the bio-interference screw sheath. Using the bio-interference screw sheath not only protects the articular cartilage of the medial femoral condyle but also protects the medial meniscus, posterior cruciate ligament, and skin of the AMP from injury because of the close proximity of the drill bit head to these structures during transportal drilling.