Modified tibial tunnel placement for single-bundle posterior cruciate ligament reconstruction reduces the "Killer Turn" in a biomechanical model

Anatomic versus Low Tibial Tunnel in Double-Bundle Posterior Cruciate Ligament Reconstruction: Clinical and Radiologic Outcomes with a Minimum 2-Year Follow-Up

There is currently no consensus on the optimal placement of the tibial tunnel for double-bundle posterior cruciate ligament (PCL) reconstruction. The purpose of this study was to compare the clinical and radiologic outcomes of double-bundle PCL reconstruction utilizing anatomic versus low tibial tunnels. We conducted a retrospective cohort study involving patients who underwent double-bundle PCL reconstruction between Jan 2019 and Jan 2022, with a minimum follow-up of 2 years (n = 36). Based on the tibial tunnel position on postoperative computed tomography, patients were categorized into two groups: anatomic placement (group A; n = 18) and low tunnel placement (group L; n = 18). We compared the range of motion, stability test, complications, and side-to-side differences in tibial posterior translation using kneeling stress radiography between the two groups. There were no significant differences between the groups regarding clinical outcomes or complication rates. No significant differences in the posterior drawer test and side-to-side difference on kneeling stress radiography (2.5 ± 1.2 mm in group A vs. 3.7 ± 2.0 mm in group L; p = 0.346). In conclusion, the main findings of this study indicate that both anatomic tunnel and low tibial tunnel placements in double-bundle PCL reconstruction demonstrated comparable and satisfactory clinical and radiologic outcomes, with similar overall complication rates at the 2-year follow-up.

A modified anatomical posterior cruciate ligament reconstruction technique using the posterior septum and posterior capsule as landmarks to position the low tibial tunnel

BACKGROUND

Lowering the exit position of the tibial tunnel can improve the clinical efficacy of posterior cruciate ligament (PCL) reconstruction, however, there is no unified positioning standard. This study aimed to use novel soft tissue landmarks to create a low tunnel.

METHODS

A total of 14 human cadaveric knees and 12 patients with PCL injury were included in this study. Firstly, we observed the anatomical position between the PCL, posterior septum, and other tissue, and evaluated the relationship between the center of the low tibial tunnel (SP tunnel) and posterior septum and distal reflection of posterior capsule, and using computed tomography (CT) to evaluate distance between the center of the SP tunnel with bony landmarks. Then, evaluated the blood vessels content in the posterior septum with HE staining. Finally, observed the posterior septum and distal reflection of the posterior capsule under arthroscopy to explore the clinical feasibility of creating a low tibial tunnel, and assessed the risk of surgery by using ultrasound to detect the distance between the popliteal artery and the posterior edge of tibial plateau bone cortex.

RESULTS

In all 14 cadaveric specimens, the PCL tibial insertions were located completely within the posterior medial compartment of the knee. The distance between the center of the SP tunnel and the the articular surface of tibial plateau was 9.4 ± 0.4 mm. All SP tunnels retained an intact posterior wall, which was 1.6 ± 0.3 mm from the distal reflection of the posterior capsule. The distances between the center of the SP tunnel and the the articular surface of tibial plateau, the champagne glass drop-off were 9.2 ± 0.4 mm (ICC: 0.932, 95%CI 0.806-0.978) and 1.5 ± 0.2 mm (ICC:0.925, 95%CI 0.788-0.975) in CT image. Compared with the posterior capsule, the posterior septum contained more vascular structures. Last, all 12 patients successfully established low tibial tunnels under arthroscopy, and the distance between the posterior edge of tibial plateau bone cortex and the popliteal artery was 7.8 ± 0.3, 9.4 ± 0.4 and 7.4 ± 0.3 mm at 30°, 60° and 90° flexion angels after filling with water and supporting with shaver in posterior-medial compartment of knee joint.

CONCLUSIONS

A modified low tibial tunnel could be established in the PCL anatomical footprint by using the posterior septum and posterior capsule as landmarks.

Biomechanical evaluation of a novel transtibial posterior cruciate ligament reconstruction using high-strength sutures in a porcine bone model

Background:

Multiple techniques are commonly used for posterior cruciate ligament (PCL) reconstruction. However, the optimum method regarding the fixation of PCL reconstruction after PCL tears remains debatable. The purpose of this study was to compare the biomechanical properties among three different tibial fixation procedures for transtibial single-bundle PCL reconstruction.

Methods:

Thirty-six porcine tibias and porcine extensor tendons were randomized into three fixation study groups: the interference screw fixation (IS) group, the transtibial tubercle fixation (TTF) group, and TTF + IS group (n = 12 in each group). The structural properties of the three fixation groups were tested under cyclic loading and load-to-failure. The slippage after the cyclic loading test and the stiffness and ultimate failure load after load-to-failure testing were recorded.

Results:

After 1000 cycles of cyclic testing, no significant difference was observed in graft slippage among the three groups. For load-to-failure testing, the TTF + IS group showed a higher ultimate failure load than the TTF group and the IS group (876.34 ± 58.78 N vs. 660.92 ± 77.74 N [P < 0.001] vs. 556.49 ± 65.33 N [P < 0.001]). The stiffness in the TTF group was significantly lower than that in the IS group and the TTF + IS group (92.77 ± 20.16 N/mm in the TTF group vs. 120.27 ± 15.66 N/m in the IS group [P = 0.001] and 131.79 ± 17.95 N/mm in the TTF + IS group [P < 0.001]). No significant difference in the mean stiffness was found between the IS group and the TTF + IS group (P = 0.127).

Conclusions:

In this biomechanical study, supplementary fixation with transtibial tubercle sutures increased the ultimate failure load during load-to-failure testing for PCL reconstruction.

All-Autograft Multiligament Knee Reconstruction of the Posterior Cruciate Ligament, Anterior Cruciate Ligament, and Posterolateral Corner (KD-IIIL)

Multiligament knee reconstruction constitutes a challenging entity. While allograft use gained popularity in this scenario because it can reduce surgery time and the risk of donor-site morbidities, in some places high-quality allografts are not readily available. In addition, allografts are subjected to some disadvantages compared with autografts, including slower biological incorporation and risk of disease transmission. Choosing and using wisely autografts to address these cases becomes valuable for these reasons. In this manuscript a technique is described for performing all-autograft multiligament knee reconstruction of the posterior cruciate ligament, anterior cruciate ligament and posterolateral corner.

Comparable Clinical and Radiologic Outcomes Between an Anatomic Tunnel and a Low Tibial Tunnel in Remnant-Preserving Posterior Cruciate Ligament Reconstruction

Background:

There is currently no consensus on the optimal placement of the tibial tunnel for remnant-preserving posterior cruciate ligament (PCL) reconstruction.

Purpose/Hypothesis:

The purpose of this study was to compare the clinical and radiologic outcomes of remnant-preserving PCL reconstruction using anatomic versus low tibial tunnels. We hypothesized that the outcomes of low tibial tunnel placement would be superior to those of anatomic tibial tunnel placement at the 2-year follow-up after remnant-preserving PCL reconstruction.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

We retrospectively reviewed the data for patients who underwent remnant-preserving PCL reconstruction between March 2011 and January 2018 with a minimum follow-up of 2 years (N = 63). On the basis of the tibial tunnel position on postoperative computed tomography, the patients were divided into those with anatomic placement (group A; n = 31) and those with low tunnel placement (group L; n = 32). Clinical scores (International Knee Documentation Committee subjective score, Lysholm score, and Tegner activity level), range of motion, complications, and stability test outcomes at follow-up were compared between the 2 groups. Graft signal on 1-year follow-up magnetic resonance imaging scans was compared between 22 patients in group A and 17 patients in group L.

Results:

There were no significant differences between groups regarding clinical scores or incidence of complications, no between-group differences in posterior drawer test results, and no side-to-side difference on Telos stress radiographs (5.2 ± 2.9 mm in group A vs 5.1 ± 2.8 mm in group L; P = .900). Postoperative 1-year follow-up magnetic resonance imaging scans showed excellent graft healing in both groups, with no significant difference between them.

Conclusion:

The clinical and radiologic outcomes and complication rate were comparable between anatomic tunnel placement and low tibial tunnel placement at 2-year follow-up after remnant-preserving PCL reconstruction. The findings of this study suggest that both tibial tunnel positions are clinically feasible for remnant-preserving PCL reconstruction.

Graft bending angle of the reconstructed posterior cruciate ligament gradually decreases as knee flexion increases

PURPOSE

The purpose of the study was to determine the change in the graft bending angles at the femoral and tibial tunnel aperture in single-bundle posterior cruciate ligament (PCL) reconstruction. It was hypothesized that different knee flexion and different tunnel directions may affect changes of the femoral and tibial graft bending angle.

METHODS

The right knees of 12 male subjects were scanned with a high-resolution computed tomography scanner at 4 different knee flexion angles (0°, 45°, 90° and 135°). To begin with, the 3D knee models were created and manipulated with the use of several modeling programs. Single-bundle PCL reconstruction was then virtually conducted in a 90° flexion model: The femoral and tibial graft bending angle, according to the various knee flexion angles, was calculated using a special software program.

RESULTS

The femoral graft bending angle significantly decreased as the knee flexion increased between 0° and 135° (all p < 0.001). The femoral graft bending angle of the AL graft showed the most obtuse angles among the three types of the graft beyond 45° of knee flexion. For the tibial graft bending angle, the anteromedial tunnel group showed significantly more acute tibial graft bending angle than the anterolateral tunnel group in all three types of the graft at all flexion angles (all p < 0.001).

CONCLUSION

Changes in the femoral graft bending angle were generally affected by different knee flexion angles. The effect of tibial tunnel direction on the tibial graft bending angle was found to be significant. The clinical relevance is that a mostly obtuse femoral graft bending angle was shown by the AL graft among three types of the graft.