Anatomic Anterior Cruciate Ligament Reconstruction

Biomechanical alterations during gait following partial ACL injury and the effectiveness of anatomical reconstruction: an in-vitro robotic investigation

Background

The biomechanical alterations of the knee throughout the gait cycle following partial anterior cruciate ligament (ACL) injuries remain unclear.

Purpose

This study aimed to investigate the changes in intra-articular contact mechanics during gait following partial ACL injury and to evaluate whether anatomical single-bundle ACL reconstruction (ACLR) could restore these altered mechanics.

Methods

Seven fresh-frozen cadaveric knee specimens were used to evaluate tibiofemoral joint biomechanics under three ligamentous conditions: intact ACL, anteromedial bundle deficiency (AMD), and single-bundle ACLR. A 6 degree of freedom (DOF) robotic system simulated gait motion using physiological loading conditions derived from human. Biomechanical parameters, including peak contact stress, displacement of contact center of stress (CCS), and regional loading patterns, were analyzed at five key gait cycle stages. Statistical analyses were performed using repeated-measures ANOVA and paired t-tests, with significance set at p < 0.05.

Results

AMD knees demonstrated a slight posterior shift in the CCS (<2 mm) during the stance phase, with significant increases in medial compartment regional loading at heel strike (4.11 ± 1.5 N, p = 0.04) and terminal stance (6.31 ± 1.35 N, p = 0.048). ACLR knees exhibited greater posterior CCS displacement in the lateral compartment at heel strike (2.73 ± 1.98 mm vs 0.21 ± 1.97 mm, p = 0.022). The sustained posterior shift in CCS will lead to abnormal loading at the posterior horn of the lateral meniscus, potentially accelerating meniscal tears or degeneration and increasing the incidence of lateral osteoarthritis. Additionally, ACLR knees exhibited significant force increases across both compartments, including the lateral compartment at terminal stance (11.91 ± 2.58 N, p = 0.027) and the medial compartment at pre-swing (11.72 ± 2.17 N, p = 0.011).

Conclusion

Anteromedial bundle injury alters medial compartment loading during gait, causing a slight posterior shift of the center of CCS. And that anatomical single-bundle ACLR does not fully replicate the native anterior cruciate ligament's biomechanical function.

Eccentric Reaming to Correct Nonanatomic Anterior Cruciate Ligament Tibial Tunnel Placement

Anatomic tibial tunnel placement remains an essential aspect of anterior cruciate ligament reconstruction success. Incorrect placement is a common cause of failure and revision reconstruction. Our technique allows repositioning a suboptimal tibial tunnel without the need to remove the initial guide pin for proper tunnel placement. The use of the eccentric reaming technique allows for this to take place, ensuring the more likely success of anterior cruciate ligament reconstruction procedures.

The role of navigation technology in anterior cruciate ligament reconstruction bone tunnel positioning

In the past decade, navigation technology-assisted bone tunnels positioning for anterior cruciate ligament reconstruction (ACLR) has received great attention. The purpose of this review is to summarize the navigation technologies applied in ACLR, describe the tunnel positioning accuracy of these technologies, and summarize their advantages and disadvantages, providing a basis for navigation technology to assist ACLR. This review discusses the limitations of traditional bone tunnel positioning methods in ACLR and further introduces various navigation techniques, focusing on their positioning accuracy and postoperative outcomes for patients. Additionally, it presents commercial systems utilizing reality-based technologies and examines their impact on the arthroscopic learning curve for less experienced surgeons. The osseous landmarks are currently the most used positioning method, but they still have shortcomings. Navigation technologies primarily focus on computer-assisted navigation, which, however, requires additional incisions. Virtual reality and augmented reality are mainly utilized in preoperative planning, with the best-reported positioning accuracy of augmented reality being 0.32 mm, while most other accuracies are within 3 mm. Mixed reality offers a novel approach for precise positioning, resulting in more optimal and consistent postoperative tunnel placement. Navigation technology improves the positioning accuracy of the bone tunnels and achieves good short-term results. Key to the future is long-term follow-up to assess clinical outcomes of navigation techniques.

Comparison of the quadrant method measuring four points and bernard method in femoral tunnel position evaluation on 3-dimensional reconstructed computed tomography after anatomical single-bundle anterior cruciate ligament reconstruction

PURPOSE

This prospective study aimed to compare the postoperative evaluation of the quadrant method measuring four points and Bernard method in femoral tunnel position evaluation on 3-Dimensional (3D) reconstructed computed tomography (CT) following the arthroscopic single-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

Thirty-eight patients with ACL tears that were reconstructed using single-bundle ACL reconstruction between May 2021 and March 2023 were included in this study. Postoperative 3D CT images were obtained after the operation. The femoral tunnel position was measured by use of the quadrant method measuring four points and Bernard method.

RESULTS

Average mean position of the femoral tunnel insertion center on the 3D CT image was at 26.16 ± 6.27% in the x-coordinate and at 24.36 ± 5.52% in the y-coordinate according to the Bernard method. Meanwhile, the position of the femoral insertion of the ACL measured by the quadrant method measuring four points was 24.2% ± 6.86% in the x-coordinate and 21.16% ± 5.14% in the y-coordinate.

CONCLUSIONS

Both the quadrant method measuring four points and Bernard method were effective in femoral tunnel position evaluation on 3D reconstructed CT. Application of the quadrant method measuring four points on 3D CT showed the advantage that measurement can be taken regardless of the shape of the bone tunnel.

The apex of the deep cartilage is a stable landmark to position the femoral tunnel during remnant-preserving anterior cruciate ligament reconstruction

PURPOSE

The aim of this retrospective cohort study was to investigate whether the apex of the deep cartilage (ADC) could help surgeons position the femoral tunnel accurately in remnant-preserving anterior cruciate ligament (ACL) reconstruction (ACLR).

METHODS

In the current retrospective cohort study, a total of 134 patients who underwent ACLR between 2016 and 2020 were included. The femoral tunnel position was located using ADC as the landmark. The patients were divided into two groups: the remnant-preserving group (RP group, n = 68) underwent remnant-preserving ACLR, and the nonremnant group (NRP group, n = 66) underwent traditional ACLR with remnant removal. Postoperatively, the femoral tunnel position was evaluated on 3D-CT. The length from the ADC to the shallow cartilage margin (L) and to the centre of the femoral tunnel (l) and the length from the centre of the femoral tunnel to a low cartilage ratio in the direction from high to low (H) were measured.

RESULTS

The l/L values of the RP and NRP groups were both 0.4 ± 0.1 after rounding (n.s.), and the H values were 9.3 ± 1.6 mm and 9.3 ± 1.7 mm, respectively (n.s.). There was no significant difference in l/L or H between the two groups. The estimation plot also showed high consistency of H and l/L of the two groups. The inter- and intraobserver reliability of I, L, l/L, and H were almost perfect.

CONCLUSIONS

The apex of the deep cartilage is a good landmark for positioning the femoral tunnel in remnant-preserving ACL reconstruction.

LEVEL OF EVIDENCE

Level III.