Accurate Positioning of Femoral and Tibial Tunnels in Single Bundle Anterior Cruciate Ligament Reconstruction Using the Indigenously Made Bernard and Hurtle Grid on a Transparency Sheet and C-arm

Marker-Less Navigation System for Anterior Cruciate Ligament Reconstruction with 3D Femoral Analysis and Arthroscopic Guidance

Accurate femoral tunnel positioning is crucial for successful anterior cruciate ligament reconstruction (ACLR), yet traditional arthroscopic techniques face significant challenges in spatial orientation and precise anatomical localization. This study presents a novel marker-less computer-assisted navigation system that integrates three-dimensional femoral modeling with real-time arthroscopic guidance. The system employs advanced image processing techniques for accurate condyle segmentation and implements the Bernard and Hertel (BH) grid system for standardized positioning. A curvature-based feature extraction approach precisely identifies the capsular line reference (CLR) on the lateral condyle surface, forming the foundation for establishing the BH reference grid. The system's two-stage registration framework, combining SIFT-ICP algorithms, achieves accurate alignment between preoperative models and arthroscopic views. Validation results from expert surgeons demonstrated high precision, with 71.5% of test groups achieving acceptable or excellent performance standards (mean deviation distances: 1.12-1.86 mm). Unlike existing navigation solutions, our system maintains standard surgical workflow without requiring additional surgical instruments or markers, offering an efficient and minimally invasive approach to enhance ACLR precision. This innovation bridges the gap between preoperative planning and intraoperative execution, potentially improving surgical outcomes through standardized tunnel positioning.

Location of the Anatomic Footprint Centers of the Anterior Cruciate Ligament Determined by Quadrant Method on Three-Dimensional Magnetic Resonance Imaging

Background

The quadrant method is widely used to determine the femoral footprint center (FFC) on radiographs or computed tomography (CT) and can also describe the tibial footprint center (TFC). However, its application on three-dimensional (3D) magnetic resonance imaging (MRI) has been limited. This study aims to describe the ACL footprint center position on 3D MRI of healthy knees using the quadrant method.

Methods

Proton density (PD) sequence 3D MRI was conducted on 45 intact knees, aged 18 to 45 years. The centers of the ACL footprints were determined, and 2D simulated radiographic images were generated from the 3D MRI data. The quadrant method was then applied to calculate the positions of the footprint centers.

Results

The FFC was located at 31.6% in the deep-shallow (DS) direction and 31.3% in the high-low (HL) direction. The TFC was positioned at 45.1% in the mediolateral (ML) direction and 39.9% in the anteroposterior (AP) direction.

Conclusions

The ACL footprint centers identified in this study were positioned similarly to previous studies, with the exception of the TFC in the ML direction, which was found to be more medial. This approach has the potential to enhance preoperative planning and intra-operative navigation in ACL reconstruction surgeries.

App-based analysis of the femoral tunnel position in ACL reconstruction using the quadrant method

PURPOSE

The purpose of this study was to examine the intra- and interobserver variability of an app-based analysis of the femoral tunnel position using the quadrant method in primary anterior cruciate ligament reconstruction.

MATERIALS AND METHODS

Between 12/2020 und 12/2021 50 patients who underwent primary anterior cruciate ligament reconstruction were included in this retrospective study. Intraoperative strictly lateral fluoroscopic images of the knee with marked femoral tunnel were analyzed by four observers using the quadrant method. For retest reliability analysis, measurements were repeated once by 2 observers after 4 weeks.

RESULTS

The femoral tunnel position of all included patients averaged 27.86% in the depth relation and 15.61% in the height relation. Statistical analysis showed an almost perfect intra- and interobserver reliability in the depth and height relation. The ICC was 0.92 in the depth relation and 0.84 in the height relation. The Pearson's correlation coefficient in the depth and height relation of observer 1 (0.94/0.81) was only slightly different from the Pearson's correlation coefficient of observer 2 (0.92/0.85). The app-based tunnel analysis took on average 59 ± 16 s per measurement.

CONCLUSION

The femoral tunnel analysis with the app-based quadrant method has an almost perfect intra- and interobserver reliability. By smartphone camera, a fast and highly accurate, if necessary also intraoperative, control of the tunnel position can be performed.

LEVEL OF EVIDENCE

Level 3-diagnostic retrospective cohort study.

App-Based Analysis of Fluoroscopic Images According to Bernard-Hertel Method for the Determination of Femoral Tunnel Positioning in Anterior Cruciate Ligament Reconstruction

The accurate positioning of the femoral tunnel is crucial for the success of anterior cruciate ligament reconstruction. Malpositioning of the tunnel is believed to be one of the most important reasons for graft failure. While use of anatomic landmarks and industry-supplied aiming devices aid the surgeon in placing the drill pin in the correct position, fluoroscopic imaging is an additional tool used intraoperatively to verify pin placement. While interpretation of fluoroscopic imaging is frequently based on eyeball measurement, a more accurate analysis of a lateral image uses the quadrant method by Bernard-Hertel. This method has been primarily used for scientific research due to its complexity and has not been integrated into clinical routine yet. We present a digital app-based approach to easily quantify the femoral pin position based on the quadrant method. This approach is mobile and easy to use. Quantification of pin position of femoral bone tunnel on a lateral fluoroscopic image may be used for quality control and teaching purposes or may provide the surgeon with additional information during ACL reconstruction.

Grid and Image Intensifier Improve Arthroscopic ACL Tunnel Position and Patient-Reported Outcomes

Purpose

To evaluate the accuracy in the femoral and tibial tunnel placement after the use of fluoroscopy along with an indigenously designed grid method to assist in arthroscopic anterior cruciate ligament reconstruction as compared with the tunnel placement without using them and to validate the findings with computed tomography scan performed postoperatively along with assessing the functional outcome at a minimum of 3 years of follow-up.

Methods

This was a prospective study conducted on patients who underwent primary anterior cruciate ligament reconstruction. Patients were included and segregated into a nonfluoroscopy (group B) and a fluoroscopy group (group A), and both had postoperative computed tomography scans so that femoral and tibial tunnel position could be evaluated. Scheduled follow-up occurred 3, 6, 12, 24, and 36 months' postoperatively. Patients were evaluated objectively with the Lachman test, measurement of range of motion, and functional outcome using patient-reported outcome measures, i.e., Tegner Lysholm Knee score, Knee injury and Osteoarthritis Outcome Score, and International Knee Documentation Committee subjective knee score.

Results

A total of 113 subjects were included. There were 53 in group A and 60 in group B. The average location of femoral tunnel showed significant differences between the 2 groups. However, the variability in femoral tunnel location was significantly lower in group A as compared with group B for proximal-distal planes only. The average location of the tibial tunnel as per the grid of Bernard et al. showed significant differences in both the planes. The variability in tibial tunnel was greater in the medial-lateral plane as compared with the anterior-posterior plane. There was a statistically significant difference in mean value of the 3 scores among the 2 groups. The variability of the scores was greater in group B as compared with group A. None of the patient was reported as a failure.

Conclusions

The results of our study suggests that fluoroscopy-guided positioning using a grid technique increases the accuracy of anterior cruciate ligament tunnel positioning with decreased variability and is associated with better patient-reported outcomes 3 years after surgery compared with tunnel positioning using landmarks.

Level of Evidence

Level II, prospective, comparative therapeutic trial.

Reconstruction of the Anterior Cruciate Ligament Using Ruler-Assisted Positioning of the Femoral Tunnel Relative to the Posterior Apex of the Deep Cartilage: A Single-Center Case Series

The techniques available to locate the femoral tunnel during anterior cruciate ligament (ACL) reconstruction have notable limitations. To evaluate whether the femoral tunnel center could be located intraoperatively with a ruler, using the posterior apex of the deep cartilage (ADC) as a landmark. This retrospective case series included consecutive patients with ACL rupture who underwent arthroscopic single-bundle ACL reconstruction at the Department of Orthopedics, Beijing Tongren Hospital between January 2014 and May 2018. During surgery, the ADC of the femoral lateral condyle was used as a landmark to locate the femoral tunnel center with a ruler. Three-dimensional computed tomography (CT) was performed within 3 days after surgery to measure the femoral tunnel position by the quadrant method. Arthroscopy was performed 1 year after surgery to evaluate the intra-articular conditions. Lysholm and International Knee Documentation Committee (IKDC) scores were determined before and 1 year after surgery. The final analysis included 82 knees of 82 patients (age = 31.7 ± 6.1 years; 70 males). The femoral tunnel center was 26 ± 1.5% in the deep-shallow (x-axis) direction and 31 ± 3.1% in the high-low (y-axis) direction, close to the "ideal" values of 27 and 34%. Lysholm score increased significantly from 38.5 (33.5-47) before surgery to 89 (86-92) at 1 year after surgery (p < 0.001). IKDC score increased significantly from 42.5 (37-47) before surgery to 87 (83.75-90) after surgery (p < 0.001). Using the ADC as a landmark, the femoral tunnel position can be accurately selected using a ruler.

Compressed Lateral and anteroposterior Anatomical Systematic Sequences «CLASS»: compressed MRI sequences with assessed anatomical femoral and tibial ACL's footprints, a feasibility study

Purpose

This study's main objective is to assess the feasibility of processing the MRI information with identified ACL-footprints into 2D-images similar to a conventional anteroposterior and lateral X-Ray image of the knee. The secondary aim is to conduct specific measurements to assess the reliability and reproducibility. This study is a proof of concept of this technique.

Methods

Five anonymised MRIs of a right knee were analysed. A orthopaedic knee surgeon performed the footprints identification. An ad-hoc software allowed a volumetric 3D image projection on a 2D anteroposterior and lateral view. The previously defined anatomical femoral and tibial footprints were precisely identified on these views. Several parameters were measured (e.g. coronal and sagittal ratio of tibial footprint, sagittal ratio of femoral footprint, femoral intercondylar notch roof angle, proximal tibial slope and others). The intraclass correlation coefficient (ICCs), including 95% confidence intervals (CIs), has been calculated to assess intraobserver reproducibility and interobserver reliability.

Results

Five MRI scans of a right knee have been assessed (three females, two males, mean age of 30.8 years old). Five 2D-"CLASS" have been created. The measured parameters showed a "substantial" to "almost perfect" reproducibility and an "almost perfect" reliability.

Conclusion

This study confirmed the possibility of generating "CLASS" with the localised centroid of the femoral and tibial ACL footprints from a 3D volumetric model. "CLASS" also showed that these footprints were easily identified on standard anteroposterior and lateral X-Ray views of the same patient, thus allowing an individual identification of the anatomical femoral and tibial ACL's footprints.

Level of evidence

Level IV diagnostic study

Femoral offset guide facilitates accurate and precise femoral tunnel placement for single-bundle anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to compare the accuracy and precision of femoral tunnel placement by expert and novice surgeons using an offset guide for single-bundle ACL reconstruction via the anteromedial (AM) portal.

METHODS

Twenty-five single-bundle ACL reconstructions performed by a novice surgeon were matched with 25 ACL reconstructions performed by an expert surgeon, based on one-to-one propensity score matching. The same technique was used by both groups for femoral tunnel placement using a 7-mm offset guide through the AM portal. Using the Bernard and Hertel grid method for postoperative three-dimensional reconstructed computed tomography, the accuracy and precision of various tunnel positions were compared.

RESULTS

No differences were found between the proximal-distal and anterior-posterior femoral tunnel placements by the two groups (proximal-distal; 30.5% involving experts, and 32.5% by novices, n.s) (anterior-posterior; 32.6% involving experts, and 31.6% by novice, n.s). The accuracy of the femoral tunnel positions, based on the average distance from the tunnel center to the center of ACL direct insertion, was similar between the two groups (n.s). No differences were found between the groups in terms of precision of femoral tunnel positions (n.s).

CONCLUSION

Novice surgeons can achieve accuracy and precision comparable to experts in creating femoral tunnels via single-bundle ACL reconstruction through the AM portal using a femoral offset guide. We recommend the use of a femoral offset guide for ACL reconstruction during the learning phase of a novice surgeon for effective tunnel placement to reduce the learning curve required to perform accurate and reproducible ACL reconstruction.

LEVEL OF EVIDENCE

Case-control study, Level III.