Tunnel position following posterior cruciate ligament reconstruction: an in vivo computed tomography analysis

Imaging Review of the Posterior Cruciate Ligament

Posterior cruciate ligament (PCL) injuries can often be missed on physical examination, especially in multiligament knee injuries. Therefore, a comprehensive approach to imaging the PCL should be implemented whenever history and examination findings indicate relative risk. Radiography, including a posterior-stress view, and magnetic resonance imaging, when available, provide consistently accurate diagnosis of PCL pathology and common knee comorbidities. Computed tomography and ultrasonography can be useful modalities with potential advantages with respect to availability and access, specific comorbidities, and/or cost-effectiveness.

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.

Tibial tunnel aperture location during single-bundle posterior cruciate ligament reconstruction: comparison of tibial guide positions

PURPOSE

We aimed to compare posterior cruciate ligament (PCL) tibial tunnel location after tibial guide insertion medial (between the PCL remnant and the medial femoral condyle) and lateral (between the PCL remnant and the anterior cruciate ligament) to the PCL stump as determined by in vivo 3-dimensional computed tomography (3D-CT).

METHODS

Tibial tunnel aperture location was analyzed by immediate postoperative in vivo CT in 66 patients who underwent single-bundle PCL reconstruction, 31 by over-the-PCL and 35 by under-the-PCL tibial guide insertion techniques. Tibial tunnel positions were measured in the medial to lateral and proximal to distal directions of the posterior proximal tibia.

RESULTS

The center of the tibial tunnel aperture was located more laterally (by 2.7 mm) in the over-the-PCL group than in the under-the-PCL group (P = .040) and by a relative percentage (absolute value/tibial width) of 3.2% (P = .031). Tibial tunnel positions in the proximal to distal direction, determined by absolute value and relative percentage, were similar in the 2 groups.

CONCLUSIONS

Tibial tunnel apertures were located more laterally after lateral-to-the-PCL tibial guide insertion than after medial-to-the-PCL tibial guide insertion. There was, however, no significant difference between these techniques in distance from the joint line to the tibial tunnel aperture. Insertion lateral to the PCL stump may result in better placement of the PCL in its anatomic footprint.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Optimal femoral tunnel positioning in posterior cruciate ligament reconstruction using outside-in drilling

PURPOSE

The goal of our study was to determine the precise femoral drill guide placement during reconstruction of the anterolateral bundle (ALB) of the posterior cruciate ligament (PCL) femoral footprint that would produce a minimum tunnel length of 25 mm, a maximum graft/femoral tunnel angle of 50°, and a minimum distance of 10 mm between the femoral socket and the subchondral bone of the weight-bearing surface of the medial femoral condyle.

METHODS

Using computer navigation, we used synthetic replicas of human femora to create a series of virtual femoral sockets. We then measured the bone tunnel length, angle of the femoral socket relative to the PCL footprint, and distance from the subchondral bone of the weight-bearing surface of the medial femoral condyle to the femoral socket at a series of guide pin sleeve positions. We positioned the guide pin using the following angle combinations: -20°, -10°, 0°, 10°, 20°, 30°, 40°, 50°, and 60° to a line perpendicular to the femoral axis in the coronal plane and -15°, 0°, 15°, 30°, 45°, and 60° to a line parallel to the transepicondylar axis in the axial plane. Using linear regression models, we determined the precise drill guide placement angles that would produce the optimal tunnel length, graft/femoral tunnel angle, and distance to the subchondral bone margin.

RESULTS

The results were consistent between small, medium, and large femora. We found that the optimal drilling angles for anatomic reconstruction of the femoral footprint of the ALB of the PCL were 0° to a line perpendicular to the femoral axis in the coronal plane and 15° to a line parallel to the transepicondylar axis in the horizontal or axial plane.

CONCLUSIONS

During outside-in drilling for PCL reconstruction, holding the guide pin sleeve at a position 0° to a line perpendicular to the femoral axis in the coronal plane and 15° to a line parallel to the transepicondylar axis in the horizontal or axial plane results in optimal bone tunnel length, graft/tunnel angle, and distance between the femoral socket and the subchondral bone of the weight-bearing surface of the medial femoral condyle.

CLINICAL RELEVANCE

We describe a precise femoral tunnel drill guide placement during outside-in PCL reconstruction that ensures an optimal femoral socket with a minimum bone tunnel length of 25 mm, maximum graft/femoral tunnel angle of 50°, and minimum distance of 10 mm between the subchondral bone of the weight-bearing surface of the medial femoral condyle and the femoral socket.

Transtibial Tunnel Placement in Posterior Cruciate Ligament Reconstruction: How It Relates to the Anatomic Footprint

Background:

It is common to place the posterior cruciate ligament (PCL) tibial tunnel with a transtibial technique using a guide that attempts to place the center of the tunnel 1 to 1.5 cm distal to the tibiofemoral joint. It is unknown how well this technique will re-create the native tibial footprint of the PCL.

Purpose:

To evaluate the accuracy of tibial tunnel placement using a transtibial technique.

Study Design:

Controlled laboratory study.

Methods:

Ten cadaveric knees from 10 donors underwent arthroscopic transtibial drilling of the tibial tunnel with use of a posteromedial portal for visualization. The transtibial guide was rested flush against the tibial spines to allow for the guide to be as distal as possible, which was between 1 and 1.5 cm distal to the tibiofemoral joint line. Using this technique, an attempt was made to place the tibial tunnels as close to the center of the PCL footprint as possible. All knees underwent computed tomography both pre- and postoperatively with a previously reported technique optimized for ligament evaluation. This allowed comparison of the anatomic PCL tibial footprint to the tibial tunnel aperture. The percentage of tunnel aperture contained within the native footprint as well as the distance from the center of the tunnel aperture to the center of the footprint was measured.

Results:

The percentage of tunnel aperture contained within the native footprint was 45.9% ± 23.1%. The distance from the center of the tibial tunnel aperture to the center of the tibial PCL footprint was 6.4 ± 2.3 mm. The tunnels were almost always (9/10) distal (or inferior) to the native footprint and either slightly lateral (5/10) or centered (5/10) in a medial to lateral direction.

Conclusion:

This study demonstrates that using the transtibial drilling technique in the tibia for PCL reconstruction places approximately half of the tibial tunnel aperture within the tibial footprint. Generally, the tunnel is distal to the footprint.

Clinical Relevance:

Consideration should be given to the fact that, using this transtibial technique, the tibial tunnel aperture is generally not placed in the center of the footprint. This may not be a negative issue, however, since there are other potential advantages from distal tunnel placement.

The use of the ligament augmentation and reconstruction system (LARS) for posterior cruciate reconstruction

PURPOSE

To systematically review and assess the use of the Ligament Advanced Reinforcement System (LARS; Surgical Implants and Devices, Arc-sur-Tille, France) for posterior cruciate ligament (PCL) reconstruction.

METHODS

A search of multiple databases was conducted using the following terms: (LARS[All Fields] AND posterior[All Fields]) OR (LARS[All Fields] AND PCL[All Fields]). The methodologic quality of each article was assessed by use of abridged Downs and Black criteria.

RESULTS

Fifty-four studies were found from the database search, of which 5 were included in the final review (4 case series and 1 case-control study). One hundred twenty-nine PCL reconstructions with LARS were performed. The mean patient age was 32.2 years, with 89 male and 40 female patients included. The mean follow-up time ranged from 10.5 to 44 months. Lysholm scores improved from a mean of 64.8 preoperatively to 89.8 postoperatively. No patients had International Knee Documentation Committee grade 1 or 2 preoperatively, with 93.0% achieving this postoperatively. Only 1 case of synovitis and 1 case of graft rupture were reported.

CONCLUSIONS

There is little evidence on the effectiveness of PCL reconstructions using LARS ligaments. What data there are show great promise, with short- and medium-term outcome data appearing favorable to autograft reconstruction. Complication rates are encouragingly low.

CLINICAL RELEVANCE

LARS has great potential for PCL reconstruction. Further studies are needed regarding the use of LARS ligaments during PCL reconstruction, including longer follow-up periods and investigation into the optimal timing for reconstruction. This may be best achieved by way of a multicenter study.

Accessory anterolateral portal in arthroscopic PCL reconstruction

PURPOSE

To evaluate the clinical and radiological results of arthroscopic PCL reconstruction using an accessory anterolateral portal for femoral tunneling and to compare these results with those of the conventional technique.

METHODS

We retrospectively reviewed the clinical and radiological results for 57 patients who underwent PCL reconstruction, including 31 patients who underwent arthroscopic PCL reconstruction with an accessory anterolateral portal (group A) and 26 patients who underwent conventional arthroscopic PCL reconstruction (group B). Lysholm score, IKDC score, simple radiographs (AP and lateral), and posterior drawer test results were evaluated preoperatively and at 3 years postoperatively.

RESULTS

No major complication was observed in group A. However, posterior cortical disruption due to improper placement of the femoral tunnel was observed in one patient in group B. The mean Lysholm knee scores increased from 41.5 ± 4.8 preoperatively to 92.5 ± 6.2 at final follow-up in group A (P < 0.001), and from 43.5 ± 3.4 preoperatively to 88.5 points ± 3.7 in group B (P = 0.002). Posterior stress radiographs with a KT-1000 showed that the mean side-to-side differences improved from 13.79 ± 5.1 mm preoperatively to 3.1 ± 0.7 mm postoperatively in group A and from 12.68 ± 6.3 mm preoperatively to 3.5 ± 0.5 mm postoperatively in group B. The sensitivity and specificity of the placement and direction of the femoral tunnel were significantly higher in group A than group B (P = 0.002).

CONCLUSION

Arthroscopic PCL reconstruction with an accessory anterolateral portal can provide a better surgical view than the conventional technique, and this can minimize the problems associated with femoral tunneling, such as inappropriate and inconsistent placement of the tunnel, abnormal angulation, and sliding of the guide tip. Moreover, this approach may have a shorter operative time and a better functional recovery than the conventional technique.

LEVEL OF EVIDENCE

Retrospective comparative study, Level IV.

Anatomic femoral tunnels in posterior cruciate ligament reconstruction: inside-out versus outside-in drilling

BACKGROUND

During posterior cruciate ligament (PCL) reconstruction, the placement and orientation of the femoral tunnel is critical to postoperative PCL function.

PURPOSE

To compare the ability of outside-in (OI) versus inside-out (IO) femoral tunnel drilling in placing the femoral tunnel aperture within the anatomic femoral footprint of the PCL, and to evaluate the orientation of the tunnels within the medial femoral condyle.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten matched pairs of cadaver knees were randomized such that within each pair, 1 knee underwent arthroscopic OI drilling and the other underwent IO drilling. All knees underwent computed tomography (CT) both pre- and postoperatively with a technique optimized for ligament evaluation (80 keV with maximum mAs). Commercially available third-party software was used to fuse the pre- and postoperative CT scans, allowing comparison of the PCL footprint to the drilled tunnel. The percentage of tunnel aperture contained within the native footprint, as well as the distance from the center of the tunnel aperture to the center of the footprint, were measured. In addition, the orientation of the tunnels in the coronal and axial planes was evaluated.

RESULTS

The OI technique placed 70.4% ± 23.7% of the tunnel within the native femoral footprint compared with 79.8% ± 16.7% for the IO technique (P = .32). The OI technique placed the center of the femoral tunnel 4.9 ± 2.2 mm from the center of the native footprint compared to 5.3 ± 2.0 mm for the IO technique (P = .65). The femoral tunnel angle in the coronal plane was 21.0° ± 9.9° for the OI technique and 37.0° ± 10.3° for the IO technique (P = .002). The tunnel angle in the axial plane was 27.3° ± 4.8° for the OI technique and 39.1° ± 11.5° for the IO technique (P = .01).

CONCLUSION

This study demonstrates no difference in the ability of the OI and IO techniques to place the femoral tunnel within the PCL femoral footprint during PCL reconstruction. With the technique parameters used in this study, the IO technique created femoral tunnels with a more vertical and anterior orientation than the OI technique.

CLINICAL RELEVANCE

Either technique can be used to place the femoral tunnel within the anatomic footprint. Consideration should be given to tunnel orientation following each technique, and what effect it has on graft bending angles, as these characteristics may affect graft strain and, ultimately, graft failure. In this regard, the IO technique likely produces gentler graft bending angles.

Greater axial trough obliquity increases the risk of graft extrusion in lateral meniscus allograft transplantation

BACKGROUND

In lateral meniscus allograft transplantation (MAT) using the keyhole method, precise trough drilling is critical for ensuring the graft is placed at the correct anatomic position to minimize the risk of extrusion. However, no study has focused on the effect of bony trough axial obliquity on graft extrusion. Our purpose was to investigate whether bony trough axial obliquity and bony trough position correlate with graft extrusion in lateral MAT using the keyhole method.

HYPOTHESIS

We hypothesized that drilling the tibial bony trough at a greater axial angle would increase the risk of graft extrusion.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The study involved 49 patients who underwent lateral MAT between 2009 and 2010 following total or subtotal meniscectomy. The mean patient age at the time of surgery was 34 years (range, 19-52 years). Graft extrusion and bony trough parameters (absolute and relative distance at the anterior, center, and posterior cuttings of the bony trough, and axial trough angle [ATA]) were assessed using conventional magnetic resonance imaging (MRI) performed on postoperative day 2. The correlation between graft extrusion and MRI trough parameters was analyzed, and multiple linear regression analysis was performed to identify predictors of graft extrusion.

RESULTS

Of the 7 MRI measurement parameters, the ATA (r = .355, P = .012), absolute anterior distance (r = .301, P = .031), and relative anterior distance (r = .307, P = .032) were found to positively correlate with absolute extrusion. The ATA (r = .296, P = .037) and relative anterior distance (r = .296, P = .039) were also found to correlate with relative extrusion. The ATA was found to be a predictor of absolute extrusion (β = .36, P = .012) and relative extrusion (β = .33, P = .019).

CONCLUSION

The risk of graft extrusion increases as the axial plane trough angle increases. The angle can be reduced by ensuring that the bony trough starting point is not created in too lateral a position.