Graft Bending Angle at the Intra-articular Femoral Tunnel Aperture After Single-Bundle Posterior Cruciate Ligament Reconstruction: Inside-Out Versus Outside-In Techniques

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.

All-Inside PCL Reconstruction, Double Bundle, With Internal Brace Augmentation

PCL reconstructive techniques are constantly evolving, and further clinical studies are needed to definitively understand the potential benefits of internal brace augmentation and anatomic double-bundle PCL reconstruction. This Technical Note reports an arthroscopic all-inside anatomic double-bundle PCL reconstruction with internal brace augmentation that is effective and reproducible.

Safe femoral tunnel drilling angles avoid injury to the medial and posteromedial femoral anatomic structures during single-bundle posterior cruciate ligament reconstruction with the inside-out technique

PURPOSE

To investigate the relationship between the medial and posteromedial femoral anatomic structures and the femoral tunnel exit produced by different tunnel orientations when creating the femoral tunnel for posterior cruciate ligament reconstruction (PCLR) using the inside-out (IO) technique and to estimate safe tunnel orientations to minimize the risk of iatrogenic injury to these structures.

METHODS

Eleven cadaveric knees were used. The medial and posteromedial aspects of each knee joint were dissected to reveal the "safe zone," which is a bony area that avoids the distribution or attachment of at-risk structures (MCL, PMC structures, and articular cartilage), while remaining 10 mm away from the articular cartilage. The hypothesis of this study was that by creating the femoral tunnel at specific angles using the IO technique, the tunnel outlet would be as close to the safe zone as possible, protecting the at-risk structures from damage. Femoral tunnels were drilled at 20 different angle combinations on each specimen: 0°, 15°, 30°, 45°, and 60° relative to a line parallel to the transepicondylar axis in the axial plane, as well as 15°, 30°, 45°, and 60° relative to a line parallel to the femoral axis in the coronal plane. The positional relationship between each tunnel exit and the safe zone was recorded, and the shortest distance between the exit center and the safe zone boundary was measured.

RESULTS

The risk of iatrogenic injury differed depending on the drilling orientation (χ² = 168.880, P < 0.001). Femoral drilling angle combinations of 45/45°, 45/60°, 60/30°, 60/45°, and 60/60° (axial/coronal) were considered relatively safer than other orientations (P < 0.05). The shortest distance between the tunnel exit and the safe zone boundary was negatively correlated with the angle in the axial plane (P < 0.001, r = - 0.810).

CONCLUSIONS

When creating the IO femoral tunnel for single-bundle PCL reconstruction, angle combinations of 45/45°, 45/60°, 60/30°, 60/45°, and 60/60° (axial/oblique coronal) could be utilized to prevent at-risk structures from being damaged. The drilling angles and the safe zone can be employed to optimize the femoral tunnel in PCLR.

Different femoral tunnel placement in posterior cruciate ligament reconstruction: a finite element analysis

BACKGROUND

At present, there is no consensus on the optimal biomechanical method for Posterior cruciate ligament (PCL) reconstruction, and the "critical corner" that is produced by the femoral tunnel is currently considered to be one of the main reasons for PCL failure. Thus, the purpose of this study was to identify one or several different tunnels of the femur, thereby reducing the influence of the "critical corner" without reducing the posterior stability of the knee.

METHODS

CT and MRI data of the knee joint of a healthy adult man were collected, and computer-related software was used to reconstruct the finite element model of the knee joint, to provide different properties to different materials and to allow for the performance of a finite element analysis of the reconstructed model. The position of the femoral tunnel was positioned and partitioned according to anatomical posture, and three areas were divided (the antero-proximal region, the antero-distal region and the posterior region). In addition, we applied a posterior tibial load of 134 N to the reconstructed model, recorded and compared different tunnels of the femur, conducted peak stress at the flexion of the knee joint of 0°, 30°, 60° and 90°, and elicited the displacement of the proximal tibia.

RESULTS

Among the 20 different femoral tunnels, the graft peak stress was lower in tunnels 4, 12 and 18 than in the PCL anatomical footpath tunnel 13, especially at high flexion angles (60° and 90°). These three tunnels did not increase the posterior displacement of the proximal tibia compared with the anatomical footpath tunnel 13.

CONCLUSION

In summary, among the options for PCL reconstruction of the femoral tunnel, the tunnels located 5 mm distal to the footprint and 5 mm anterior to the footprint could reduce the peak stress of the graft; additionally, it may reduce the "critical corner" and was shown to not reduce the posterior stability of the knee joint.

Effects of flexible reamer on the femoral tunnel characteristics in anterior cruciate ligament reconstruction

To compare the femoral tunnel characteristics using a rigid versus flexible reamer during anterior cruciate ligament reconstruction. It was hypothesized that the employment of a flexible reamer along with femoral tunnel would exhibit longer tunnel length and more acute femoral graft tunnel angle compared to the case of a rigid reamer.The study population included 28 patients who underwent anatomical single-bundle anterior cruciate ligament reconstruction using transportal technique and were able to take postoperative computed tomography (CT) evaluation. Of these, the femoral tunnel of 14 cases was drilled with a flexible reamer (group I) and in another 14 cases drill was performed with a conventional rigid reamer (group II). The femoral tunnel in group I was made at 90° of knee flexion. In group II, the femoral tunnel was created at 120° of knee flexion. The parameters of the femoral tunnels were compared in terms of the femoral tunnel length and femoral graft tunnel angle. Special software was used to create and manipulate (3-D) 3-dimensional knee models.The difference in the mean femoral tunnel locations expressed in percentage distance between the 2 groups was not significantly different. The mean femoral tunnel length of group I was significantly longer than that of group II, (P = .03, 36.7 ± 2.9 vs 32.9 ± 9.0 mm). The angle formed by the femoral tunnel and the graft in group I was significantly smaller than in group II (P = .01, 109.8° ± 9.4° vs 118.1° ± 7.2°).Our data suggest that the flexible reamer can provide sufficient tunnel length for the suspensory fixation with a fixed loop. Whereas, the femoral graft-tunnel angle through flexible reaming at 90° of knee flexion was more acute compared to rigid reaming at 120° of knee flexion.Study Design: level of evidence III.

Editorial Commentary: The Posterior Cruciate Ligament Posteromedial Bundle Is Small but Vital to Posterior Cruciate Ligament Biomechanics: Don't Ignore the Underdog

Posterior cruciate ligament (PCL) reconstruction leads to outcomes less favorable than those of anterior cruciate ligament reconstruction. In recent years, we have seen a surge of publications regarding PCL anatomy, isometry, and reconstruction techniques. PCL reconstruction has been revolutionized with lessons learned from analysis of PCL behavior, such as the distinct role of the posteromedial bundle (PMB) in the biomechanics of the knee at different flexion angles, as well as its co-dominant role with its counterpart, the anterolateral bundle. With the knee in extension, the PMB serves to restrict posterior translation, whereas in knee flexion, the PMB restricts internal rotation. It is rather too early to know whether the biomechanical advantage of double-bundle reconstruction will result in better clinical outcomes in the long term; however, the increased interest and the refinement of both single- and double-bundle reconstruction techniques will certainly advance our knowledge, ultimately translating into better patient outcomes.

Lower Tibial Tunnel Placement in Isolated Posterior Cruciate Ligament Reconstruction: Clinical Outcomes and Quantitative Radiological Analysis of the Killer Turn

Background

The "killer turn" effect after posterior cruciate ligament (PCL) reconstruction is a problem that can lead to graft laxity or failure. Solutions for this situation are currently lacking.

Purpose

To evaluate the clinical outcomes of a modified procedure for PCL reconstruction and quantify the killer turn using 3-dimensional (3D) computed tomography (CT).

Study design

Case series; Level of evidence, 4.

Methods

A total of 15 patients underwent modified PCL reconstruction with the tibial aperture below the center of the PCL footprint. Next, 2 virtual tibial tunnels with anatomic and proximal tibial apertures were created on 3D CT. All patients were assessed according to the Lysholm score, International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, Tegner score, side-to-side difference (SSD) in tibial posterior translation using stress radiography, and 3D gait analysis.

Results

The modified tibial tunnel showed 2 significantly gentler turns (superior, 109.87° ± 10.12°; inferior, 151.25° ± 9.07°) compared with those reconstructed with anatomic (91.33° ± 7.28°; P < .001 for both comparisons) and proximal (99° ± 7.92°; P = .023 and P < .001, respectively) tibial apertures. The distance from the footprint to the tibial aperture was 16.49 ± 3.73 mm. All patient-reported outcome scores (mean ± SD) improved from pre- to postoperatively: Lysholm score, from 46.4 ± 18.87 to 83.47 ± 10.54 (P < .001); Tegner score, from 2.47 ± 1.85 to 6.07 ± 1.58 (P < .001); IKDC sports activities score, from 19 ± 9.90 to 33.07 ± 5.35 (P < .001); and IKDC knee symptoms score, from 17.87 ± 6.31 to 25.67 ± 3.66 (P < .001). The mean SSD improved from 9.15 ± 2.27 mm preoperatively to 4.20 ± 2.31 mm postoperatively (P < .001). The reconstructed knee showed significantly more adduction (by 1.642°), less flexion (by 1.285°), and more lateral translation (by 0.279 mm) than that of the intact knee (P < .001 for all).

Conclusion

Lowering the tibial aperture during PCL reconstruction reduced the killer turn, and the clinical outcomes remained satisfactory. However, SSD and clinical outcomes were similar to those of previously described techniques using an anatomic tibial tunnel.

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.

[The killer turn in the posterior cruciate ligament reconstruction: mechanism and improvement]

OBJECTIVE

To summarize the research progress of killer turn in posterior cruciate ligament (PCL) reconstruction.

METHODS

The literature related to the killer turn in PCL reconstruction in recent years was searched and summarized.

RESULTS

The recent studies show that the killer turn is considered to be the most critical cause of graft relaxation after PCL reconstruction. In clinic, this effect can be reduced by changing the fixation mode of bone tunnel, changing the orientation of bone tunnel, squeezing screw fixation, retaining the remnant, and grinding the bone at the exit of bone tunnel. But there is still a lack of long-term follow-up.

CONCLUSION

There are still a lot of controversies on the improved strategies of the killer turn. More detailed basic researches focusing on biomechanics to further explore the mechanism of the reconstructed graft abrasion are needed.

Posterior Cruciate Ligament All-Inside Reconstruction

Several techniques for posterior cruciate ligament (PCL) reconstruction have been described. Reported clinical outcomes for the various techniques are often affected by concomitant injuries. Therefore, the optimal surgical technique choice remains controversial. Variations include transtibial versus tibial inlay, single-bundle versus double-bundle, and autograft versus allograft. The all-inside technique has recently been described as a transtibial method that uses adjustable loop suspensory fixation through sockets rather than tunnels on both the femur and tibia. This technique preserves more bone and may decrease the risk of tunnel convergence during multiligament reconstruction or concomitant meniscus procedures. This paper outlines the options available to surgeons performing PCL reconstruction and describes the authors' preferred technique for all-inside PCL reconstruction.

Influence of Graft Bending Angle on Graft Maturation, the Femoral Tunnel, and Functional Outcomes by 12 Months After Anterior Cruciate Ligament Reconstruction

Background:

The graft bending angle (GBA), the angle between the femoral bone tunnel and the line connecting the femoral and tibial tunnel apertures, has been proven to influence stress within the graft and could be an important factor in graft healing within the joint and bone tunnel. However, the influence of the GBA on functional outcomes, particularly on return to sports (RTS), is rarely reported.

Purpose/Hypothesis:

The purpose of this study was to investigate the influence of the GBA on graft maturation, the femoral tunnel, and functional outcomes at 12 months after anterior cruciate ligament reconstruction (ACLR). We hypothesized that a greater GBA might be related to bone tunnel widening, poor graft healing, and inferior functional outcomes after ACLR.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A total of 43 consecutive patients who underwent unilateral ACLR with hamstring tendon autografts participated in this study. Their knees were evaluated using functional scores (International Knee Documentation Committee [IKDC] score, Lysholm knee activity score, Tegner activity scale, RTS) and the anterior tibial translation side-to-side difference (ATTD), as measured using a KT-1000 arthrometer and 3.0-T magnetic resonance imaging (MRI), at 12 months after surgery. Based on MRI, the signal/noise quotient (SNQ) of the graft, the GBA, and the femoral tunnel diameter were measured.

Results:

The mean GBA was 56° (range, 41°-69°). The GBA had a significant positive correlation with the SNQ (rho, 0.45; P = .003) and bone tunnel diameter (rho, 0.35; P = .02), but it had no significant correlation with any functional scores. Patients were divided into 3 groups based on GBA values: low GBA (LGBA; 40° < GBA ≤ 50°), middle GBA (MGBA; 50° < GBA ≤ 60°), and high GBA (HGBA; 60° < GBA ≤ 70°). The HGBA group had a significantly higher mean SNQ than both the LGBA (P = .01) and MGBA groups (P = .02). It also had a greater mean tunnel diameter than the LGBA group (P = .04). There was no significant difference in IKDC scores, Lysholm scores, ATTD, Tegner scores, or rates of RTS among groups.

Conclusion:

The GBA did not affect functional outcomes at 12 months after ACLR, although it affected the SNQ of the graft and the femoral tunnel diameter.

Variation in Graft Bending Angle During Range of Motion in Single-Bundle Posterior Cruciate Ligament Reconstruction: A 3-Dimensional Computed Tomography Analysis of 2 Techniques

PURPOSE

To compare variations in femoral graft bending angle during range of motion (ROM) of the knee between inside-out (IO) and retro-socket outside-in (OI) techniques in posterior cruciate ligament (PCL) reconstruction using in vivo 3-dimensional (3D) computed tomography analysis.

METHODS

Ten patients underwent PCL reconstruction by the IO technique (5 patients) or the retro-socket OI technique (5 patients) for suspensory femoral fixation. After PCL reconstruction, 3D computed tomography was performed in 0° extension and 90° flexion to reconstruct 3D femur and tibia bone models using Mimics software. Positions of femur and tibia at 30°, 45°, and 60° flexion were reproduced by determining the kinematic factors of anteroposterior translation, mediolateral translation, and internal-external rotation angle of each patient based on previously measured kinematic data. Variation in graft bending angle according to the flexion range of the knee was calculated by the difference in graft angulation measured at each flexion angle. The results were compared between the 2 techniques.

RESULTS

There was significant difference in variation of femoral graft bending angle between IO and retro-socket OI techniques from 0° to 90° flexion of the knee (P = .008). Significant difference was also noticed at 30° to 45° (P = .008), 45° to 60° (P = .008), and 60° to 90° (P = .016) ROM of the knee between the 2 groups.

CONCLUSIONS

The retro-socket OI technique resulted in less variation in femoral graft bending angle compared with the IO technique during knee ROM. We recommend the retro-socket OI technique for femoral tunnel placement to reduce the graft motion at the intra-articular femoral tunnel aperture.

CLINICAL RELEVANCE

The retro-socket OI technique produces significantly less variation in femoral graft bending angle when compared with the IO technique. Such reduction in variation of femoral graft bending angle might be related to lower stress at the femoral tunnel aperture.

Editorial Commentary: Posterior Cruciate Ligament Femoral Techniques: The "Critical Corner" Is Just Not as Exciting as the "Killer Turn"

The "killer turn" between the graft and tibial tunnel in posterior cruciate ligament reconstruction has always been of technical and clinical importance. The "critical corner" of the graft and femoral tunnel has garnered less interest. Technical advances in arthroscopic instrumentation have allowed a move from inside-out to outside-in techniques, which can assist with tunnel placement and drilling. While these techniques do not impact the "killer turn," they have been demonstrated to decrease the acuity of the "critical corner," but there remains no evidence of impact on graft rupture or clinical outcomes.

Graft bending angle affects allograft tendon maturity early after anterior cruciate ligament reconstruction

PURPOSE

The aim of this study was to clarify the association of the anterior cruciate ligament (ACL) graft bending angle and graft maturity of autograft and allograft tendons using high-resolution MRI.

METHODS

Patients with unilateral ACL reconstruction were invited to participate in this study, and they were examined using a 3.0-T MRI scan at 3, 6 and 12 months after the operation. Anatomic single-bundle ACL reconstruction was performed on 48 patients using the trans-portal technique, including 28 with autograft hamstring tendons and 20 with allograft tendons. To evaluate graft healing, the signal/noise quotient (SNQ) was measured in four regions of interest (ROIs) of the femoral tunnel, proximal, midsubstance and distal ACL grafts. The graft bending angle was defined as the angle between the femoral bone tunnel and the line connecting the femoral and tibial tunnel apertures. Graft SNQ and graft bending angle were assessed at 3, 6 and 12 months postoperatively, and the association between SNQ and the average graft bending angle was analyzed.

RESULTS

Generally, the mean graft bending angle of this cohort increased gradually with time. The SNQ value of each graft region increased from 3 to 6 months and then decreased from 6 to 12 months. In the whole cohort, the graft bending angle had a significant positive association with graft SNQ in the femoral tunnel or proximal site. In the allograft subgroup, the graft bending angle had a significant positive association with the graft SNQ in the femoral tunnel or proximal site at 6 months after surgery, while there was no association between the graft bending angle and SNQ at 12 months. In the autograft subgroup, the graft bending angle had a significant positive association with graft SNQ in the femoral tunnel or proximal site at 12 months after surgery.

CONCLUSION

Generally, the graft bending angle was correlated with a high signal intensity of the proximal graft in the early postoperative period for allograft tendons and in the late postoperative period for allograft tendons. This suggests that the biomechanical effect from the graft bending angle on graft healing may be different for allografts and autografts after ACL reconstruction.

LEVEL OF EVIDENCE

III.

Location of the femoral tunnel aperture during single-bundle posterior cruciate ligament reconstruction: outside-in versus inside-out techniques

PURPOSE

Placement of the femoral tunnel is critical to graft function after posterior cruciate ligament (PCL) reconstruction. To date, however, the location of the femoral tunnel aperture has not been compared by in vivo 3-dimensional computed tomography (3D-CT) during PCL reconstruction with the outside-in (OI) and inside-out (IO) techniques. This study used 3D-CT analysis to compare the location of the femoral tunnel aperture in patients who underwent PCL reconstruction with the OI and IO techniques.

METHODS

A total of 77 patients underwent single-bundle PCL reconstruction using the OI (n = 46) or IO (n = 31) technique. The location of the femoral tunnel aperture was assessed by 3D-CT and measured by the anatomic coordinate axis method to construct 3D surface models.

RESULTS

The mean location of the femoral tunnel aperture in the low-to-high direction did not differ significantly in the OI and IO groups (75.0 vs. 75.2%, P = 0.869). However, in the deep-to-shallow direction, the femoral tunnel aperture was positioned more shallowly in the IO than in the OI group (75.7 vs. 81.1%, P < 0.001).

CONCLUSION

The IO technique of single-bundle PCL reconstruction yielded a shallower femoral tunnel in the deep-to-shallow direction than did the OI technique. However, femoral tunnel location in the low-to-high direction was similar using the two techniques.

Combined reconstruction of the posterior cruciate ligament and medial collateral ligament using a single femoral tunnel

PURPOSE

Lesions of the medial collateral ligament (MCL) are the most common knee ligament injuries, and lesions associated with the anterior cruciate ligament or the posterior cruciate ligament (PCL) in knee dislocations should be reconstructed to prevent failure of the central pivot reconstruction. The purpose of this study was to evaluate the outcomes of combined PCL/MCL reconstruction using a single femoral tunnel with a minimum 2-year follow-up.

METHOD

A retrospective study of thirteen patients with combined PCL/MCL injuries was conducted. The patients underwent PCL and MCL reconstruction using an Achilles tendon allograft with a single tunnel in the medial femoral condyle, thereby avoiding tunnel conversion.

RESULTS

All patients achieved a range of motion of at least 100°. The mean loss of extension and flexion values compared to the contralateral side was 1° ± 2° and 9° ± 10°, respectively. Our results included 26 reconstructions with three (11.5 %) failures, two in the PCL (15.3 %) and one in the MCL (7.6 %), in three different patients. In the final evaluation, the mean IKDC subjective score was 71.63 ± 16.23, the mean Lysholm score was 80.08 ± 13.87, and the median Tegner score was 6 (range = 2-7).

CONCLUSION

The PCL/MCL reconstruction technique using a single femoral tunnel and an Achilles tendon allograft is safe, avoids the convergence of tunnels in the medial femoral condyle, has excellent results, and is reproducible.

LEVEL OF EVIDENCE

IV.

Evaluating the Femoral-Side Critical Corner in Posterior Cruciate Ligament Reconstruction: The Effect of Outside-In Versus Inside-Out Creation of Femoral Tunnels on Graft Contact Pressure in a Synthetic Knee Model

PURPOSE

To characterize and compare the graft contact characteristics of outside-in (OI) and inside-out (IO) femoral tunnels during single-bundle reconstruction of the anterolateral bundle of the posterior cruciate ligament in a synthetic knee model.

METHODS

Femoral tunnels were separately made in 16 synthetic femora (8 OI and 8 IO). Achilles tendon allografts were fixed using suspensory fixation with a pressure sensor between the allograft and femoral tunnel. Grafts were cyclically loaded; force, contact area, contact pressure, and peak pressure at the aperture were measured. This process was repeated using the same allograft to assess the other tunnel angle in a separate specimen.

RESULTS

IO specimens showed higher mean contact pressure at all loading cycles, with significance shown at 50 N (P = .02). Peak pressure was also greater in IO specimens at all loading cycles and reached statistical significance at 100 N (P = .04). IO specimens had a lower contact area at 150 N (P = .04). No statistically significant differences in force were observed between the 2 groups.

CONCLUSIONS

OI creation of the femoral tunnel for anterolateral bundle reconstruction of the posterior cruciate ligament resulted in decreased mean and peak contact pressures at the femoral aperture compared with IO tunnel creation at the specific trajectories and loading parameters tested in this synthetic femoral model. These biomechanical data suggest that OI creation of the femoral tunnel may help reduce in vivo graft contact pressure at the femoral aperture.

CLINICAL RELEVANCE

These data suggest that a tunnel drilled from OI may result in less graft pressure at the femoral aperture, which may prevent graft elongation and optimize graft survival.