Reconstruction technique affects femoral tunnel placement in ACL reconstruction

Is Anterior Cruciate Ligament Reconstruction "Silva Technique" Equal to All-Inside Techniques? A Prospective Single-Center Study: An Alternative ACL All-Inside Reconstruction Technique Using a Tibial Tunnel and Bone Graft

Background: The development of less invasive all-inside techniques regarding anterior cruciate ligament (ACL) reconstruction surgery has been associated with various advantages, including fewer complications and reduced postoperative pain. Silva et al. described a quadruple semitendinosus graft construct and suspensory button fixation for ACL reconstruction as an alternative technique. At the end of this technique, the tibial tunnel is filled with a bone autograft plug. This paper aims to examine the incorporation of the autograft and thus evaluate whether the "Silva technique" provides the same benefits as all-inside techniques. Methods: A prospective study assessed 31 patients undergoing ACL reconstruction surgery using the "Silva technique." The cases involved in the study were skeletally mature patients with no previous history of ACL surgery or multiligamentous instability. All patients followed the same rehabilitation program and were examined at three standardized follow-up visits: 4 months, 8 months, and 1 year postoperatively. Tegner-Lysholm knee score (TLKS), visual analog score (VAS) for pain, and the IKDC subjective knee score were completed at every visit. A knee MRI scan was performed at every scheduled visit to assess bone graft incorporation and remodeling. Results: TLKS scores revealed a considerable improvement compared to preoperative figures, from 57.2 points preoperatively to an average of 99.4 at the 12-month follow-up (p < 0.0001). VAS scores were substantially ameliorated after the operation and until the second follow-up visit, from 5 before surgery to zero 8 months after the operation, with no noteworthy alterations afterward (p < 0.0001). IKDC subjective knee score outcomes were found to have increased at the last follow-up, from 59.3 prior to surgery to 99.8 12 months postoperatively (p < 0.0001). Regarding the MRI features of the bone autograft, the tibial tunnel was entirely filled by bone formation at the last MRI scan, suggesting complete integration of the autograft in all patients. Conclusions: Bone autograft employed to seal the tibial tunnel was completely incorporated in all cases 1 year postoperatively. The "Silva technique" appears to feature all the avails of all-inside techniques, whilst it seems to be simpler and easier than them after the surgeon is familiarized with its particular aspects. It is a robust option in orthopedic surgeons' arsenal. However, further large-scale pertinent research is requisite to confirm the findings of this study.

Transtibial versus anteromedial transportal femoral tunnel in single-bundle anterior cruciate ligament reconstruction: a systematic review and meta-analysis of prospective randomized controlled trials

The purpose of this study was to systematically review and meta-analyze randomized controlled trials (RCTs) reporting the comparative clinical and functional outcomes, postoperative complications, and radiological outcomes of single-bundle anterior cruciate ligament reconstruction (ACLR) performed using the transtibial (TT) approach or anteromedial (AM) technique. A systematic review of the literature was performed according to Cochrane and PRISMA guidelines. RCTs comparing TT and AM techniques were considered only. The quality of the studies was defined using the GRADE system, and the risk of bias was assessed with the RoB 2 tool. The primary endpoint was to systematically review and meta-analyze the clinical outcomes, residual laxity and failure rate of both AM and TT techniques. In the current meta-analysis 13 RCTs involving 989 patients who underwent arthroscopic single-bundle ACLR (486 TT and 503 AM) were included. Patients undergoing AM technique resulted in higher objective-IKDC (p < 0.001) and Lysholm scores (p = 0.002), despite a lower incidence of pathological anterior tibial translation (p < 0.001) and positive pivot-shift test (p < 0.001). No differences were detected in IKDC subjective score (p = 0.26), Tegner activity scale (p = 0.18) and graft failure (p = 0.07). ACL reconstruction through AM portal technique provides better clinical outcomes and lower incidence of residual rotational and anteroposterior laxity in comparison with the TT technique. No statistically significant difference in subjective outcomes and graft failure was reported.

Optimal tibial tunnel angulation for anatomical anterior cruciate ligament reconstruction using transtibial technique

Numerous studies have suggested that the primary cause of failure in transtibial anterior cruciate ligament reconstruction (ACLR) is often attributed to non-anatomical placement of the bone tunnels, typically resulting from improper tibial guidance. We aimed to establish the optimal tibial tunnel angle for anatomical ACLR by adapting the transtibial (TT) technique. Additionally, we aimed to assess graft bending angle (GBA) and length changes during in vivo dynamic flexion of the knee. Twenty knee joints underwent a CT scan and dual fluoroscopic imaging system (DFIS) to reproduce relative knee position during dynamic flexion. For the single-legged lunge, subjects began in a natural standing position and flexed the right knee beyond 90° When performing the lunge task, the subject supported the body weight on the right leg, while the left leg was used to keep the balance. The tibial and femoral tunnels were established on each knee using a modified TT technique for single-bundle ACLR. The tibial tunnel angulation to the tibial axis and the sagittal plane were measured. Considering that ACL injuries tend to occur at low knee flexion angles, GBA and graft length were measured between 0° and 90° of flexion in this study. The tibial tunnel angulated the sagittal plane at 42.8° ± 3.4°, and angulated the tibial axis at 45.3° ± 5.1° The GBA was 0° at 90° flexion of the knee and increased substantially to 76.4 ± 5.5° at 0° flexion. The GBA significantly increased with the knee extending from 90° to 0° (p < 0.001). The ACL length was 30.2mm±3.0 mm at 0° flexion and decreased to 27.5mm ± 2.8 mm at 90° flexion (p = 0.072). To achieve anatomic single-bundle ACLR, the optimal tibial tunnel should be angulated at approximately 43° to the sagittal plane and approximately 45° to the tibial axis using the modified TT technique. What's more, anatomical TT ACLR resulted in comparable GBA and a relatively constant ACL length from 0° to 90° of flexion. These findings provide theoretical support for the clinical application and the promotion of the current modified TT technique with the assistance of a robot to achieve anatomical ACLR.

Evaluating femoral graft placement using three-dimensional magnetic resonance imaging in the reconstruction of the anterior cruciate ligament via independent or transtibial drilling techniques: a retrospective cohort study

PURPOSE

Anterior cruciate ligament (ACL) reconstruction is a common surgical procedure, yet failure still largely occurs due to nonanatomically positioned grafts. The purpose of this study was to retrospectively evaluate patients with torn ACLs before and after reconstruction via 3D MRI and thereby assess the accuracy of graft position on the femoral condyle.

METHODS

Forty-one patients with unilateral ACL tears were recruited. Each patient underwent 3D MRI of both knees before and after surgery. The location of the reconstructed femoral footprint relative to the patient's native footprint was compared.

RESULTS

Native ACL anatomical location of the native ACL had a significant impact on graft position. Native ACLs that were previously more anterior yielded grafts that were more posterior (3.70 ± 1.22 mm, P = 0.00018), and native ACL that were previously more proximal yielded grafts that were more distal (3.25 ± 1.09 mm, P = 0.0042). Surgeons using an independent drilling method positioned 76.2% posteriorly relative to the native location, with a mean 0.1 ± 2.8 mm proximal (P = 0.8362) and 1.8 ± 3.0 mm posterior (P = 0.0165). Surgeons using a transtibial method positioned 75% proximal relative to the native location, with a mean 2.2 ± 3.0 mm proximal (P = 0.0042) and 0.2 ± 2.6 mm posterior (P = 0.8007). These two techniques showed a significant difference in magnitude in the distal-proximal axis (P = 0.0332).

CONCLUSION

The femoral footprint position differed between the native and reconstructed ACLs, suggesting that ACL reconstructions are not accurate. Rather, they are converging to a normative reference point that is neither anatomical nor isometric.

Risk factors for reoperation for arthrofibrosis following primary anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study is to identify the rate and risk factors for a reoperation for arthrofibrosis following primary anterior cruciate ligament (ACL) reconstruction.

METHODS

Prospective data recorded in the New Zealand ACL Registry were cross-referenced with data from the Accident Compensation Corporation (ACC). Primary ACL reconstructions performed between April 2014 and May 2021 were analysed. The ACC database was used to identify patients who underwent a reoperation for a diagnosis of arthrofibrosis. Multivariable survival analysis was performed to compute adjusted hazard ratios (aHR) and 95% confidence intervals.

RESULTS

A total of 12,296 primary ACL reconstructions were analysed, of which 230 underwent a reoperation for arthrofibrosis (1.9%) at a mean follow-up of 3.6 years. A higher risk of arthrofibrosis was observed in females (aHR = 1.76, p = 0.001), patients with a history of previous knee surgery (aHR = 1.82, p = 0.04) and when a transtibial drilling technique was used (aHR = 1.53, p = 0.03). ACL reconstruction >6 months after injury had the lowest rate of arthrofibrosis (1.3%, aHR = 0.45, p = 0.01). There was no difference in risk between early surgery within 6 weeks versus delayed surgery between 6 weeks and 6 months after injury (2.9% versus 2.1%, aHR = 0.78, not significant).

CONCLUSION

Female sex, previous knee surgery and a transtibial drilling technique increased the risk of reoperation for arthrofibrosis. Early surgery within 6 weeks of injury was not associated with an increased risk when compared with surgery between 6 weeks and 6 months after injury.

LEVEL OF EVIDENCE

Level III.

Freehand vs. Medial Portal Offset Aimer Technique for Accurate Femoral Tunnel Placement in Arthroscopic ACL Reconstruction

Purpose

In this study, our aim was to reveal the effect of the medial femoral offset aimer usage through the femoral tunnel entry and exit points and the tunnel length during femoral tunnel drilling in arthroscopic anterior cruciate ligament (ACL) reconstruction.

Methods

One hundred patients who underwent arthroscopic single-bundle ACL reconstruction were included in the study. Group 1 consisted of 50 patients who underwent femoral tunnel drilling using a medial portal offset aimer device, while Group 2 consisted of 50 patients who were operated on using the freehand technique. Both groups were compared in terms of femoral tunnel and graft tunnel lengths, femoral tunnel angle in the coronal plane, and the location of the femoral tunnel entry and exit points.

Results

The mean femoral tunnel and graft tunnel lengths were significantly longer in Group 2 (p = 0.000). There was no significant difference in terms of localization of the femoral tunnel entry point in both the axial and sagittal planes. The tunnel exit point was located significantly more posterior in Group 1 in the axial plane (p = 0.028). There was no significant difference in terms of the coronal plane femoral tunnel angle between the two groups.

Conclusion

In arthroscopic ACL reconstructions, more successful results may be obtained with the freehand technique compared to drilling with a femoral offset aimer. For an experienced orthopedic surgeon, using a medial portal offset aimer device during femoral tunnel drilling does not seem necessary.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43465-023-00929-z.

Biomechanical Analysis of Ideal Knee Flexion Angle for ACL Graft Tensioning Utilizing Multiple Femoral and Tibial Tunnel Locations

Anterior cruciate ligament (ACL) graft failure rate has been reported to be greater than 5% at 5 years. Our study evaluated ACL excursion with anatomic and nonanatomic femoral and tibial tunnels to determine optimal flexion angle to tension the ACL to minimize excursion. Ten cadaveric knee specimens were used. The ACL was sectioned and the femoral and tibial attachments were marked. A 1/16-inch drill created a tunnel in the center of the ACL footprint on the tibia and femur and additional tunnels were made 5 mm from this. A suture was passed through each tunnel combination and attached to a string potentiometer. The knee was ranged from full extension to 120 degrees of flexion for 10 cycles while mounted in a custom fixture. The change in length (excursion) of the suture during movement was recorded for each combination of femoral and tibial tunnels. Anatomic reconstruction of the ACL with tunnel placement in the center of the femoral and tibial footprint did not result in an isometric graft, with excursion of the ACL during knee motion of 7.46 mm (standard deviation [SD]: 2.7mm), greatest at 2.84 degrees of flexion (SD: 4.22). The tunnel combination that resulted in the least excursion was a femoral footprint 5 mm anterior to the femoral and 5 mm posterior to the tibial footprint (4. 2mm, SD: 1.37 mm). The tunnel combination that resulted in the most excursion utilized femoral footprint 5 mm proximal to the femoral and 5 mm posterior to the tibial footprint (9.81 mm, SD: 2.68 mm). Anatomic ACL reconstruction results in significant excursion of the ACL throughout motion. If not tensioned properly, the ACL can stretch during range of motion, potentially leading to rerupture. To prevent stretching of the graft, the current biomechanical study recommends tensioning an anatomic ACL reconstruction at its point of maximal excursion, or between 0 and 5 degrees of flexion. The level of evidence is IV.

Effect of Surgical Design Variations on the Knee Contact Behavior during Anterior Cruciate Ligament Reconstruction

In this study, we aimed to develop an in-silico synthesis of the effect of critical surgical design parameters on articular contact behavior for a bone-patellar-tendon-bone anterior cruciate ligament reconstruction (ACL-R) surgery. A previously developed finite element model of the knee joint consisting of all relevant soft tissues was employed. The knee model was further updated with additional features to develop the parametric FE model of the biomechanical experiments that depicted the ACL-R surgery. The parametricity was created involving femoral tunnel architecture (orientations and locations) and graft fixation characteristics (pretension and angle of fixation). A global sensitivity analysis based on variance decomposition was used to investigate the contribution of the surgical parameters to the uncertainty in response to the ACL-R joint. Our examinations indicated that the total contact force was primarily influenced by either combined or individual action of the graft pretension and fixation angle, with a modest contribution of the graft insertion sites. The joint contact center and area were affected mainly by the angle of fixation and the tunnel placements. Graft pretension played the dominant role in the maximum contact pressure variability, an observation that has been well-documented in the literature. Interestingly, the joint contact behavior was almost insensitive to the tunnel's coronal and sagittal orientations. Our data provide an evaluation of how the surgical parameters affect the knee joint's contact behavior after ACL-R and may provide additional information to better explain the occurrence of osteoarthritis as an aftermath of such surgery.

Association Between Anteromedial Portal Versus Tibial Tunnel Drilling and Meniscal Reoperation Risk Following Anterior Cruciate Ligament Reconstruction: A Cohort Study

BACKGROUND

Anterior cruciate ligament reconstruction (ACLR) provides functional stability to an injured knee. While multiple techniques can be used to drill the femoral tunnel during ACLR, a single technique has yet to be proven as clinically superior. One marker of postoperative functional stability is subsequent meniscal tears; a lower risk of subsequent meniscal surgery could be expected with improved knee stability.

PURPOSE

To determine if there is a meniscal protective effect when using an anteromedial portal (AMP) femoral tunnel drilling technique versus transtibial (TT) drilling.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Data from Kaiser Permanente's ACLR registry were used to identify patients who had a primary isolated ACLR between 2009 and 2018; those with previous surgery in the index knee and meniscal pathology at the time of ACLR were excluded. The exposure of interest was TT (n = 2711) versus AMP (n = 5172) drilling. Multivariable Cox proportional hazard regression was used to evaluate the risk of a subsequent ipsilateral meniscal reoperation with adjustment for age, sex, femoral fixation, and graft choice. We observed a shift in surgeon practice from the TT to AMP over the study time frame; therefore, the relationship between technique and surgeon experience on meniscal reoperation was evaluated using an interaction term in the model.

RESULTS

At the 9-year follow-up, the crude cumulative meniscal reoperation probability for AMP procedures was 7.76%, while for TT it was 5.88%. After adjustment for covariates, we observed a higher risk for meniscal reoperation with AMP compared with TT (hazard ratio [HR], 1.53; 95% CI, 1.05-2.23). When stratifying by surgeon experience, this adverse association was observed for patients who had their procedure performed by surgeons with less AMP experience (no previous AMP ACLR: HR, 1.26; 95% CI, 0.84-1.91) while a protective association was observed for patients who had their procedure with more experienced surgeons (40 previous AMP ACLRs: HR, 0.34; 95% CI, 0.13-0.92).

CONCLUSION

Drilling the femoral tunnel via the AMP was associated with a higher risk of subsequent meniscal surgery compared with TT drilling. However, when AMP drilling was used by surgeons experienced with the technique, a meniscal protective effect was observed.

Transtibial versus independent femoral tunnel drilling techniques for anterior cruciate ligament reconstruction: evaluation of femoral aperture positioning

Background

Femoral tunnel can be drilled through tibial tunnel (TT), or independent of it (TI) by out-in (OI) technique or by anteromedial (AM) technique. No consensus has been reached on which technique achieves more proper femoral aperture position because there have been evolving concepts in the ideal place for femoral aperture placement. This meta-analysis was performed to analyze the current literature comparing femoral aperture placement by TI versus TT techniques in ACL reconstruction.

Methods

We performed a comprehensive systematic review and meta-analysis of English-language literature in PubMed, Cochrane, and Web of Science databases for articles comparing femoral aperture placement by TI versus TT techniques with aperture position assessed by direct measurement or by postoperative imaging, PXR and/or CT and/or MRI.

Results

We included 55 articles with study population of 2401 knees of whom 1252 underwent TI and 1149 underwent TT techniques. The relevant baseline characteristics, whenever compared, were comparable between both groups. There was nonsignificant difference between TI and TT techniques in the distance from aperture center to footprint center and both techniques were unable to accurately recreate the anatomic footprint position. TI technique significantly placed aperture at more posterior position than TT technique. TI technique significantly lowered position of placed aperture perpendicular to Blumensaat’s line (BL) than TT technique, and modifications to TT technique had significant effect on this intervention effect. Regarding sagittal plane aperture placement along both AP anatomical axis and BL, there was nonsignificant difference between both techniques.

Conclusion

Modifications to TT technique could overcome limitations in aperture placement perpendicular to BL. The more anterior placement of femoral aperture by TT technique might be considered, to some extent, a proper position according to recent concept of functional anatomical ACL reconstruction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03040-5.

Freehand Anatomic Transtibial Single-Bundle Anterior Cruciate Ligament Reconstruction

Creation of the femoral tunnel for single-bundle anterior cruciate ligament (ACL) reconstruction has a high rate of nonanatomic placement with the transtibial (TT) technique but yields better restoration with the anteromedial portal technique and close restoration of the anatomic femoral footprint with the outside-in technique. Modifications of the traditional (TT) technique have been described to restore the native femoral ACL footprint and to simulate double-bundle reconstruction. Modified TT techniques try to capture the anatomic femoral footprint through an anatomic tibial tunnel. In the technique described in this article, the anatomic femoral footprint is drilled first by the use of a 2.5-mm Kirschner wire through the parapatellar anteromedial portal, making an angle 30° to the sagittal plane and 20° to the horizontal plane. The wire is drilled while the knee is hyperflexed and then withdrawn from outside until its distal end reaches the intercondylar notch. The wire is then advanced in an antegrade manner while the knee is flexed 90° until it reaches the center of the marked tibial footprint. The angle of knee flexion may be slightly increased or decreased around 90° with or without slight internal rotation to capture the anatomic tibial footprint. The procedure is completed as a TT single-bundle ACL reconstruction.

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.

The Ideal Cortical Button Location on the Lateral Femur for Anterior Cruciate Ligament Suspensory Fixation is 30 mm Proximal to the Lateral Epicondyle

Purpose

To determine the ideal location for anterior cruciate ligament (ACL) suspensory cortical button placement on the lateral femur with the highest failure load and to establish the relationship of tunnel diameter and cortical thickness on load to failure.

Methods

Computed tomography (CT) data were obtained from 45 cadaveric distal femurs. A Cartesian coordinate system was established along the lateral femur with the lateral epicondyle (LE) as a reference point. Locations 0, 20 and 30 mm from the LE along lines 0°, 25°, 50°, and 75° posterioproximal from the axial plane were created. Tunnels connecting from each location to the center of the ACL footprint were simulated. Cortical thickness and long axis diameter of the oval cortical holes were determined for each location. Based on the CT data, custom drill guides were created and used to drill 4.5 mm tunnels at each lateral femur location to the ACL footprint on the cadaver femurs. Cortical buttons were placed at each location and pulled using a servohydraulic testing system. The correlation of tunnel diameter and cortical thickness to button failure load were analyzed using a regression analysis.

Results

Significant differences were found for failure load (P<.0001) and cortical thickness between the locations tested (P<.0001). The location 30 mm proximal from the LE and 75⁰ from the axial plane had the highest failure load of 573 N. A regression analysis (R² = .15) indicated that the cortical thickness was significantly correlated with load to failure (P <.0001), whereas the long-axis diameter was not (P = .33).

Conclusion

The ideal cortical button location on the lateral femur for ACL suspensory fixation was located 30 mm proximal from the lateral epicondyle, based on this area’s high failure load. Oblique tunnel drilling of this proximal location may cause a larger long-axis diameter cortical hole, but the cortex is also thicker, which is more closely correlated with failure load.

Clinical Relevance

Different ACL suspensory cortical button locations on the lateral femur have different failure loads based on the cortical thickness of the bone supporting the button. It is important for surgeons to understand which drilling techniques place the button in a proximal and posterior location, especially if the bone quality of the patient is of concern.

Influence of Graft Bending Angle on Femoral Tunnel Widening After Double-Bundle ACL Reconstruction: Comparison of Transportal and Outside-In Techniques

Background:

Previous studies have suggested that increased mechanical stress due to acute graft bending angle (GBA) is associated with tunnel widening and graft failure after anterior cruciate ligament (ACL) reconstruction. Few studies have compared the GBA between the outside-in (OI) and the transportal (TP) techniques.

Purpose:

To evaluate the influence of GBA on clinical outcomes and tunnel widening after ACL reconstruction with OI versus TP technique.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Included in the study were 56 patients who underwent double-bundle ACL reconstruction (n = 28 in the OI group and n = 28 in the TP group). Clinical outcomes (Lysholm, International Knee Documentation Committee, Tegner score, and knee laxity) 1 year postoperatively were evaluated. Computed tomography scans at 5 days and 1 year postoperatively were used for imaging measurements, and the femoral tunnel was divided into the proximal third, middle, and aperture sections. The GBA and cross-sectional area (CSA) were measured using image analysis software and were compared between groups. A correlation analysis was performed to determine if the GBA affected clinical outcomes or tunnel widening.

Results:

No significant difference was observed in clinical outcomes between the groups. The GBA of both the anteromedial (AM) and posterolateral bundles were more acute in the OI group compared with the TP group (P < .05). The CSA at the AM tunnel aperture increased significantly in the OI group (84.2% ± 64.3%) compared with the TP group (51.4% ± 36.7%) (P = .04). However, there were no differences in the other sections. In the Pearson correlation test, GBA was not correlated with tunnel widening or clinical outcomes.

Conclusion:

Regardless of technique, the GBA did not have a significant influence on tunnel widening or clinical outcomes. Considering a wider AM tunnel aperture, a more proximal and posterior AM tunnel position might be appropriate with the OI technique.

Clinical and Radiological Outcomes of Anteromedial Portal Versus Transtibial Technique in ACL Reconstruction: A Systematic Review

Background:

The drilling technique used to make a femoral tunnel is critically important for determining outcomes after anterior cruciate ligament (ACL) reconstruction. The 2 most common methods are the transtibial (TT) and anteromedial (AM) techniques.

Purpose:

To determine whether graft orientation and placement affect clinical outcomes by comparing clinical and radiological outcomes after single-bundle ACL reconstruction with the AM versus TT technique.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

Articles in PubMed, EMBASE, the Cochrane Library, ISI Web of Science, Scopus, and MEDLINE were searched from inception until April 25, 2020, using the following Boolean operators: transtibial OR trans-tibial AND (anteromedial OR trans-portal OR independent OR three portal OR accessory portal) AND anterior cruciate ligament.

Results:

Of 1270 studies retrieved, 39 studies involving 11,207 patients were included. Of these studies, 14 were clinical, 13 were radiological, and 12 were mixed. Results suggested that compared with the TT technique, the AM technique led to significantly improved anteroposterior and rotational knee stability, International Knee Documentation Committee (IKDC) scores, and recovery time from surgery. A higher proportion of negative Lachman (P = .0005) and pivot-shift test (P = .0001) results, lower KT-1000 arthrometer maximum manual displacement (P = .00001), higher Lysholm score (P = .001), a higher incidence of IKDC grade A/B (P = .05), and better visual analog scale score for satisfaction (P = .00001) were observed with the AM technique compared with the TT technique. The AM drilling technique demonstrated a significantly shorter tunnel length (P = .00001). Significant differences were seen between the femoral and tibial graft angles in both techniques. Low overall complication and revision rates were observed for ACL reconstruction with the AM drilling technique, similar to the TT drilling technique.

Conclusion:

In single-bundle ACL reconstruction, the AM drilling technique was superior to the TT drilling technique based on physical examination, scoring systems, and radiographic results. The AM portal technique provided a more reproducible anatomic graft placement compared with the TT technique.

ACL Reconstruction Graft Angle and Outcomes: Transtibial vs Anteromedial Reconstruction

BACKGROUND

The importance of creating an anatomic anterior cruciate ligament (ACL) reconstruction has been receiving significant attention. The best technique by which to achieve this anatomic reconstruction continues to be debated. The two most common methods are the transtibial (TT) and anteromedial (AM) techniques. Each has its advantages and disadvantages, and the literature comparing the two remains uncertain.

QUESTIONS/PURPOSES

In this prospective comparative study, we aimed to compare the ACL graft and tunnel angles achieved using the anatomic transtibial (TT) and anteromedial (AM) techniques; compare the ACL graft and tunnel angles in knees that have undergone ACL reconstruction and knees with intact ACLs; and determine whether differences in the graft or tunnel angle produce differences in clinical outcomes, as measured using both physical exam and patient-reported outcomes, after ACL reconstruction.

METHODS

Patients who underwent primary ACL reconstruction with bone-tendon-bone grafts using a TT or AM technique were included. Femoral graft angle (FGA), tibial graft angle (TGA), and sagittal orientation of the reconstructed ACL and contralateral native ACL were measured on post-operative magnetic resonance imaging. Post-operatively, patients underwent measurement of knee stability and completed the Knee Injury and Osteoarthritis Outcome Score (KOOS) survey.

RESULTS

Twenty-nine patients were enrolled (AM group, 14; TT group, 15); at follow-up, KOOS data were available for 26 patients (13 in each group). There were no differences in sagittal ACL graft angle between groups or in comparison with the normal knee. The FGA was more vertical after TT reconstructions; the TGA was comparable between groups. There were no significant differences in 2-year post-operative physical exam measurements or in KOOS scores.

CONCLUSION

Anatomic ACL angle was restored after reconstruction with both the TT and AM techniques, despite different FGAs. No significant differences in clinical outcome were noted between groups on physical exam or KOOS at 2 years after surgery. These results suggest that TT reconstruction results in a graft position similar to that seen in AM reconstruction and that the location of the intra-articular tunnel aperture matters more than the orientation of the tunnel.

Anterior Cruciate Ligament Graft Tunnel Placement and Graft Angle Are Primary Determinants of Internal Knee Mechanics After Reconstructive Surgery

BACKGROUND

Graft placement is a modifiable and often discussed surgical factor in anterior cruciate ligament (ACL) reconstruction (ACLR). However, the sensitivity of functional knee mechanics to variability in graft placement is not well understood.

PURPOSE

To (1) investigate the relationship of ACL graft tunnel location and graft angle with tibiofemoral kinematics in patients with ACLR, (2) compare experimentally measured relationships with those observed with a computational model to assess the predictive capabilities of the model, and (3) use the computational model to determine the effect of varying ACL graft tunnel placement on tibiofemoral joint mechanics during walking.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eighteen participants who had undergone ACLR were tested. Bilateral ACL footprint location and graft angle were assessed using magnetic resonance imaging (MRI). Bilateral knee laxity was assessed at the completion of rehabilitation. Dynamic MRI was used to measure tibiofemoral kinematics and cartilage contact during active knee flexion-extension. Additionally, a total of 500 virtual ACLR models were created from a nominal computational knee model by varying ACL footprint locations, graft stiffness, and initial tension. Laxity tests, active knee extension, and walking were simulated with each virtual ACLR model. Linear regressions were performed between internal knee mechanics and ACL graft tunnel locations and angles for the patients with ACLR and the virtual ACLR models.

RESULTS

Static and dynamic MRI revealed that a more vertical graft in the sagittal plane was significantly related (P < .05) to a greater laxity compliance index (R² = 0.40) and greater anterior tibial translation and internal tibial rotation during active knee extension (R² = 0.22 and 0.23, respectively). Similarly, knee extension simulations with the virtual ACLR models revealed that a more vertical graft led to greater laxity compliance index, anterior translation, and internal rotation (R² = 0.56, 0.26, and 0.13). These effects extended to simulations of walking, with a more vertical ACL graft inducing greater anterior tibial translation, ACL loading, and posterior migration of contact on the tibial plateaus.

CONCLUSION

This study provides clinical evidence from patients who underwent ACLR and from complementary modeling that functional postoperative knee mechanics are sensitive to graft tunnel locations and graft angle. Of the factors studied, the sagittal angle of the ACL was particularly influential on knee mechanics.

CLINICAL RELEVANCE

Early-onset osteoarthritis from altered cartilage loading after ACLR is common. This study shows that postoperative cartilage loading is sensitive to graft angle. Therefore, variability in graft tunnel placement resulting in small deviations from the anatomic ACL angle might contribute to the elevated risk of osteoarthritis after ACLR.

No difference in revision rates between anteromedial portal and transtibial drilling of the femoral graft tunnel in primary anterior cruciate ligament reconstruction: early results from the New Zealand ACL Registry

PURPOSE

The use of an accessory anteromedial portal to drill the femoral graft tunnel in primary anterior cruciate ligament (ACL) reconstruction was introduced in the 2000s in an effort to achieve a more anatomic femoral tunnel position. However, some early studies reported an increase in revision ACL reconstruction compared to the traditional transtibial technique. The aim of this study was to analyse recent data recorded by the New Zealand ACL Registry to compare outcomes of ACL reconstruction performed using the anteromedial portal and transtibial techniques.

METHODS

Analysis was performed on primary isolated single-bundle ACL reconstructions recorded between 2014 and 2018 by the New Zealand ACL Registry. Patients were categorised into two groups according to whether an anteromedial portal or transtibial technique was used to drill the femoral graft tunnel. The primary outcome was revision ACL reconstruction and was compared between both groups through univariate and multivariate survival analyses. The secondary outcomes that were analysed included subscales of the Knee Injury and Osteoarthritis Outcome Score (KOOS) and Marx activity score.

RESULTS

Six thousand one hundred and eighty-eight primary single-bundle ACL reconstructions were performed using either the anteromedial portal or transtibial drilling techniques. The mean time of follow-up was 23.3 (SD ± 14.0) months. Similar patient characteristics such as mean age (29 years, SD ± 11), sex (males = 58% versus 57%) and time to surgery (median 4 months, IQR 5) were observed between both groups. The rate of revision ACL reconstruction was 2.6% in the anteromedial portal group and 2.2% in the transtibial group (n.s.). The adjusted risk of revision ACL reconstruction was 1.07 (95% CI 0.62-1.84, n.s.). Patients in the anteromedial portal group reported improved scores for subscales of the KOOS and higher Marx activity scores at 1-year post-reconstruction.

CONCLUSION

There was no difference in the risk of revision ACL reconstruction between the two femoral tunnel drilling techniques at short-term follow-up. We observed minor differences in patient-reported outcomes at 1-year follow-up favouring the anteromedial portal technique, which may not be clinically relevant. Surgeons can achieve good clinical outcomes with either drilling technique.

LEVEL OF EVIDENCE

III.

Outcomes Following Arthroscopic Single and Double Bundle Anterior Cruciate Ligament (ACL) Reconstruction Supported by the Comprehensive Early Rehabilitation Program (CERP)

Background

The aim of this study was to compare the level of functional condition in patients who had rehabilitation with the comprehensive early rehabilitation program (CERP) following either single bundle (SB) or double bundle (DB) anterior cruciate ligament reconstruction (ACLR) using semitendinosus-gracilis tendon graft (ST-G) method. We hypothesized that 12 weeks after reconstruction followed by a rehabilitation program, there would be a difference in clinical results and functional activity between patients.

Material/Methods

This study included 94 patients who had rehabilitation with CERP after knee surgery for a knee injury from a recreational sport. There were 49 patients in Group 1 (mean age, 36.5 years) who had CERP after SB ACLR, and 45 patients in Group 2 (mean age, 35.6 years) who had CERP after DB ACLR. Functional condition was tested using the Lysholm Knee Scoring Scale, and knee stability was measured using KT-2000. The first examination was performed before CERP and the second examination was performed 12 weeks later.

Results

The level of functional condition in both groups was similar before rehabilitation with CERP, with no significant difference (P<0.958) and was considered relatively low. In the second examination, 12 weeks after starting CERP, the patients improved in both groups. The improvement was larger in the SB ACLR Group 1 than in the DB ACLR Group 2. The difference was significant (P<0.005). However, the patients in Group 2 achieved better knee stability scores in the KT-2000 examination than the patients in Group 1. The difference was significant (P=0.035).

Conclusions

We found that the patients from both groups after 12 weeks of CERP achieved an improvement in stability and functional activity within normal limits. However, SB ACLR was more effective than DB ACLR in terms of the level of functionality achieved with CERP but was less effective in terms of knee stability.

Clinico-radiological outcomes following anatomical anterior cruciate ligament reconstruction using the TransLateral, all-inside technique

We present early clinical outcomes of patients following anatomical anterior cruciate ligament reconstruction using a TransLateral, single bundle, all-inside technique with a one-year follow-up and radiological evaluation of socket position. Eligible Patients who underwent a primary ACL reconstruction, using the TransLateral, all-inside technique alone, between Jan 2013 and Feb 2016 were included in this study. Of this group, all patients underwent isolated semitendinosus graft harvest. The Lysholm knee scores were measured preoperatively and at one-year follow-up in 40 patients who underwent ACL reconstruction. Postoperatively, antero-posterior and lateral radiographs were obtained to evaluate the position of the femoral socket (using the Bernard and Hertel Grid) and tibial socket (using the Amis-Jakob line). There were 36 males and 4 females with a mean age of 27.1 years (range 16-49). There was a single non-surgical related mortality prior to the one year follow up. We report no postoperative infections or graft failure at one year. The mean preoperative Lysholm score was 68.7 (Range: 29-95). The mean Lysholm score increased to 92.5% (Range: 59-100, p < 0.05). Evaluation of femoral sockets revealed accurate positioning on the Bernard and Hertel Grid with a mean ACL center of 27% along Blumensaat's line and 34% of the height of the intercondylar notch. The mean tibial socket position was 41.8% (Range: 32%-47%) along the Amis-Jakob Line. Our single surgeon case series utilizing the all-inside, TransLateral ACLR technique highlights good early outcomes with no postoperative complications or graft failure at one year.

Comparison of Modified Transtibial and Anteromedial Portal Techniques in Anatomic Single-Bundle ACL Reconstruction

The purpose of this study was to compare the clinical, 3-dimensional computed tomography, magnetic resonance imaging, and second-look arthroscopic findings of the modified transtibial technique with those of the anteromedial portal technique in single-bundle anterior cruciate ligament reconstruction (SB-ACLR). Among patients who underwent SB-ACLR from February 2012 to May 2014, 95 patients with a minimum of 36 months of follow-up were included in this retrospective study. Forty-five patients underwent a reconstruction using the modified transtibial technique. Fifty patients underwent a reconstruction using the anteromedial portal technique. Clinical scores and stabilities were recorded preoperatively and at final follow-up. All patients had postoperative computed tomography and the computed tomography parameters, including tunnel position and graft obliquity, evaluated. Additionally, postoperative magnetic resonance imaging and second-look arthroscopy were performed. On the basis of the functional and stability outcomes, all of the patients showed significant improvement after SB-ACLR, with no significant differences existing between the 2 groups (P>.05). Tunnel position and obliquity were not significantly different between the 2 groups (P>.05). There were no statistically significant differences between the 2 groups regarding the magnetic resonance imaging and second-look arthroscopy findings (P>.05). The tunnel characteristics and clinical results of the 2 techniques were comparable. Given the several advantages of the modified transtibial technique, including its simplicity and patients' greater activity level, it is suitable for anatomic SB-ACLR. [Orthopedics. 2019; 42(2):83-89.].

Comparison of Modified Transtibial and Outside-In Techniques in Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction

PURPOSE

To compare the bending angle of anterior cruciate ligament (ACL) graft at femoral tunnel, graft maturation, and tunnel positions and the clinical outcomes of the modified transtibial (mTT) and outside-in (OI) techniques.

METHODS

Patients who met the inclusion criteria were divided into the mTT group (n = 50) and the OI group (n = 50). Using 3-dimensional computed tomography (3-D CT), tunnel placement and femoral tunnel bending angle were analyzed. The 3.0-T magnetic resonance imaging (MRI) was used to assess the graft signal intensity (indicative of maturation) with signal/noise quotient (SNQ). Graft tension and synovialization were evaluated with second-look arthroscopy in all cases. Clinical and functional tests were completed at 36 months of follow-up.

RESULTS

When tunnel placements were analyzed using the quadrant method, no significant differences were found between the mTT group and the OI group. The femoral graft bending angle was reduced in the mTT group, and the total mean of SNQ values and mean SNQ values at the femoral intraosseous and proximal graft of the mTT group were significantly lower than in the OI group (P < .001), respectively. The femoral graft bending angle on the coronal and axial planes showed moderate-to-strong correlation with the SNQ values at the femoral intraosseous and proximal graft. Second-look arthroscopy revealed better synovialization in the mTT group than in the OI group (P = .040), with no significant difference in graft tension between the 2 groups (P = .328).

CONCLUSIONS

Anatomic tunnel placements did not vary between the mTT group and the OI group. However, the mTT group had more benefits in femoral graft bending angle and showed higher graft maturity and better synovial coverage than the OI group, although there were no significant differences in clinical outcomes. The acute femoral graft bending angle might negatively affect the maturation of proximal graft. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

American Society of Biomechanics Clinical Biomechanics Award 2017: Non-anatomic graft geometry is linked with asymmetric tibiofemoral kinematics and cartilage contact following anterior cruciate ligament reconstruction

BACKGROUND

Abnormal knee mechanics may contribute to early cartilage degeneration following anterior cruciate ligament reconstruction. Anterior cruciate ligament graft geometry has previously been linked to abnormal tibiofemoral kinematics, suggesting this parameter may be important in restoring normative cartilage loading. However, the relationship between graft geometry and cartilage contact is unknown.

METHODS

Static MR images were collected and segmented for eighteen subjects to obtain bone, cartilage, and anterior cruciate ligament geometries for their reconstructed and contralateral knees. The footprint locations and orientation of the anterior cruciate ligament were calculated. Volumetric, dynamic MR imaging was also performed to measure tibiofemoral kinematics, cartilage contact location, and contact sliding velocity while subjects performed loaded knee flexion-extension. Multiple linear regression was used to determine the relationship between non-anatomic graft geometry and asymmetric knee mechanics.

FINDINGS

Non-anatomic graft geometry was related to asymmetric knee mechanics, with the sagittal plane graft angle being the best predictor of asymmetry. A more vertical sagittal graft angle was associated with greater anterior tibial translation (β = 0.11mmdeg, P = 0.049, R2 = 0.22), internal tibial rotation (β = 0.27degdeg, P = 0.042, R2 = 0.23), and adduction angle (β = 0.15degdeg, P = 0.013, R2 = 0.44) at peak knee flexion. A non-anatomic sagittal graft orientation was also linked to asymmetries in tibial contact location and sliding velocity on the medial (β = -4.2mmsdeg, P = 0.002, R2 = 0.58) and lateral tibial plateaus (β = 5.7mmsdeg, P = 0.006, R2 = 0.54).

INTERPRETATION

This study provides evidence that non-anatomic graft geometry is linked to asymmetric knee mechanics, suggesting that restoring native anterior cruciate ligament geometry may be important to mitigate the risk of early cartilage degeneration in these patients.

Femoral Footprint for Anatomical Single-Bundle Anterior Cruciate Ligament Reconstruction: A Cadaveric Study

Purpose

To identify the femoral footprint of the anterior cruciate ligament (ACL) in Koreans.

Materials and Methods

Eighteen embalmed cadaveric knees (mean age, 70 years) were examined. First, the shape of the ACL was determined macroscopically. After the ACL femoral footprint was defined, the ACL was cut from the femur and a Kirschner wire was inserted into the center of the ACL, and the position was verified with a C-arm. The position was quantified on the C-arm field using the quadrant method. The length and width of the ACL were measured.

Results

Macroscopically, the ACL is a flat single bundle with an average length of 34 mm and an average width of 9 mm. On average, the center of the ACL insertion site measured with the quadrant method was positioned at 29.5%±2.8% in an anterior direction (from posterior), and at 38.5%±3.2% in a distal direction (from Blumensaat’s line). The anterior and posterior margins of the ACL femoral footprint were the resident’s ridge and the cartilage margin of the lateral femoral condyle, respectively.

Conclusions

The center of the ACL femoral footprint is positioned more anteriorly and distally than the positions identified in previous studies.

Validation of an MRI Protocol for Routine Quantitative Assessment of Tunnel Position in Anterior Cruciate Ligament Reconstruction

BACKGROUND

No standardized methodology and objective criteria currently exist to accurately and objectively assess tunnel placement and consequent graft orientation in anterior cruciate ligament (ACL) reconstruction (ACLR) through a single imaging modality. Advances in magnetic resonance imaging (MRI) technology have enabled the use of volumetric high spatial and contrast resolution proton density-weighted sequencing, which allows precise delineation of graft orientation, tunnel position, and quantitative assessment of tunnel position relationship to adjacent reproducible anatomic landmarks.

PURPOSE

To establish an MRI protocol that would provide an accurate alternative to 3-dimensional computed tomography (3D-CT) for standardized assessment of bone tunnel placement in ACLR, as a component of assessing ACLR outcomes and to assist in presurgical planning for revision ACLR.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

Twenty-four participants diagnosed with a failed ACLR underwent MRI and 3D-CT per the imaging protocols of the Sydney Orthopaedic Research Institute, in which the acquired data were converted to 3D models. The bone tunnels of the previous ACLR were then intraoperatively digitized at the tunnel aperture and along the length of the tunnel (barrel) and used as the reference standard to evaluate the accuracy of high-resolution MRI and 3D-CT. Differences in geometry between the image-based model and the reference point cloud were calculated through point-to-point comparison.

RESULTS

At the tunnel apertures, no significant differences were detected between the MRI and 3D-CT models versus the reference models for the femur ( P = .9472) and tibia ( P = .5779). Mean ± SD tunnel barrel deviations between MRI and 3D-CT were 0.48 ± 0.28 mm (femur) and 0.46 ± 0.27 mm (tibia). No significant differences were detected between the MRI and 3D-CT models versus the reference models for the femoral ( P = .5730) and tibial ( P = .3002) tunnel barrels.

CONCLUSION

This study demonstrated that, in addition to being the optimum modality for assessment of soft tissue injury of the knee, a high-resolution 3D turbo spin echo proton density sequence can provide an accurate assessment of tunnel placement, without the use of ionizing radiation. Therefore, this protocol provides the foundation for an objective standardized platform to quantitatively evaluate the location of ACL bone tunnels and graft orientation for routine postoperative assessment, presurgical planning, and evaluation of clinical outcomes.

A Prospective Evaluation of Femoral Tunnel Placement for Anatomic Anterior Cruciate Ligament Reconstruction Using 3-Dimensional Magnetic Resonance Imaging

BACKGROUND

The recent emphasis on anatomic reconstruction of the anterior cruciate ligament (ACL) is well supported by clinical and biomechanical research. Unfortunately, the location of the native femoral footprint can be difficult to see at the time of surgery, and the accuracy of current techniques to perform anatomic reconstruction is unclear.

PURPOSE

To use 3-dimensional magnetic resonance imaging (3D MRI) to prospectively evaluate patients with torn ACLs before and after reconstruction and thereby assess the accuracy of graft position on the femoral condyle.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Forty-one patients with unilateral ACL tears were recruited into the study. Each patient underwent 3D MRI of both the injured and uninjured knees before surgery. The contralateral (uninjured) knee was used to define the patient's native footprint. Patients then underwent ACL reconstruction, and the injured knee underwent reimaging after surgery. The location and percentage overlap of the reconstructed femoral footprint were compared with the patient's native footprint.

RESULTS

The center of the native ACL femoral footprint was a mean 12.0 ± 2.6 mm distal and 9.3 ± 2.2 mm anterior to the apex of the deep cartilage. The position of the reconstructed graft was significantly different, with a mean distance of 10.8 ± 2.2 mm distal ( P = .02) and 8.0 ± 2.3 mm anterior ( P = .01). The mean distance between the center of the graft and the center of the native ACL femoral footprint (error distance) was 3.6 ± 2.6 mm. Comparing error distances among the 4 surgeons demonstrated no significant difference ( P = .10). On average, 67% of the graft overlapped within the native ACL femoral footprint.

CONCLUSION

Despite contemporary techniques and a concerted effort to perform anatomic ACL reconstruction by 4 experienced sports orthopaedic surgeons, the position of the femoral footprint was significantly different between the native and reconstructed ACLs. Furthermore, each surgeon used a different technique, but all had comparable errors in their tunnel placements.

The Effect of Hamstring Tendon Autograft Harvest on the Restoration of Knee Stability in the Setting of Concurrent Anterior Cruciate Ligament and Medial Collateral Ligament Injuries

BACKGROUND

A hamstring autograft is commonly used in anterior cruciate ligament (ACL) reconstruction (ACLR); however, there is evidence to suggest that the tendons harvested may contribute to medial knee instability.

HYPOTHESIS

We tested the hypothesis that the gracilis (G) and semitendinosus (ST) tendons significantly contribute to sagittal, coronal, and/or rotational knee stability in the setting of ACLR with a concurrent partial medial collateral ligament (MCL) injury.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve human cadaveric knees were subject to static forces applied to the tibia including an anterior-directed force as well as varus, valgus, and internal and external rotation moments to quantify laxity at 0°, 30°, 60°, and 90° of flexion. The following ligament conditions were tested on each specimen: (1) ACL intact/MCL intact, (2) ACL deficient/MCL intact, (3) ACL deficient/partial MCL injury, and (4) ACLR/partial MCL injury. To quantify the effect of muscle loads, the quadriceps, semimembranosus, biceps femoris, sartorius (SR), ST, and G muscles were subjected to static loads. The loads on the G, ST, and SR could be added or removed during various test conditions. For each ligament condition, the responses to loading and unloading the G/ST and SR were determined. Three-dimensional positional data of the tibia relative to the femur were recorded to determine tibiofemoral rotations and translations.

RESULTS

ACLR restored anterior stability regardless of whether static muscle loads were applied. There was no significant increase in valgus motion after ACL transection. However, when a partial MCL tear was added to the ACL injury, there was a 30% increase in valgus rotation ( P < .05). ACLR restored valgus stability toward that of the intact state when the G/ST muscles were loaded. A load on the SR muscle without a load on the G/ST muscles restored 19% of valgus rotation; however, it was still significantly less stable than the intact state.

CONCLUSION

After ACLR in knees with a concurrent partial MCL injury, the absence of loading on the G/ST did not significantly alter anterior stability. Simulated G/ST harvest did lead to increased valgus motion. These results may have important clinical implications and warrant further investigation to better outline the role of the medial hamstrings, particularly among patients with a concomitant ACL and MCL injury.

CLINICAL RELEVANCE

A concurrent ACL and MCL injury is a commonly encountered clinical problem. Knowledge regarding the implications of hamstring autograft harvest techniques on joint kinematics may help guide management decisions.

Three dimensionalCT analysis of femoral tunnel position after ACL reconstruction. A prospective study of one hundred and thirty five cases

BACKGROUND

One of the principal causes for failure of anterior cruciate ligament reconstruction (ACL) is femoral tunnel mal-position. Several studies compare the position of femoral tunnels achieved with various techniques, with small series and using a quadrant assessment method.

QUESTIONS

(1) What is the incidence of anatomical positioning of the intra-articular femoral tunnel aperture in primary ACL reconstruction in a university knee surgery? (2) What are the main errors in positioning?

METHODS

3D-CT scans were performed after primary ACL reconstruction in 135 consecutive cases. The intra-articular position of the femoral tunnel aperture was analyzed using the Magnussen classification.

RESULTS

The intra-articular tunnel position was deemed anatomical in 77%, intermediate in 20.8%, and non-anatomical in 2.2%. Among the mal-positioned tunnels, 54.8% were vertical, 29% were anteriorly positioned, and 16.1% were both.

CONCLUSIONS

The intra articular femoral tunnel aperture was well positioned using an outside-in technique. The main error of tunnel positioning was a tunnel too vertical.

LEVEL OF EVIDENCE

Level III, prospective study (case series).

Femoral tunnel positioning using an anteromedial technique for ACL reconstruction: A radiographic study with a cadaveric model

BACKGROUND

We studied the anatomic positioning of the femoral tunnel during simulated anterior cruciate ligament reconstruction using an anteromedial portal approach in cadaveric models.

METHODS

In thirty cadaveric human knee specimens, simulation of an arthroscopic anterior cruciate ligament reconstruction was performed and the femoral tunnel was drilled using an anteromedial portal. A Kirschner wire was passed into the tunnel and radiographs were obtained. These radiographs were then evaluated in the coronal and sagittal planes. Angles between the axis of the femoral tunnel and the joint line in the coronal plane (alpha, α) or the femoral long axis in the sagittal plane (beta, β) were calculated for each specimen. The external aperture of the femoral tunnel was defined as the point of exit of the Kirschner wire from the lateral femoral cortex. This was evaluated relative to a prescribed rectangle and coordinate axis, with the radiographic quadrant method of Bernard, to assess the accuracy of femoral tunnel placement.

RESULTS

The mean α in the coronal plane was 48.53∘, the mean β in the sagittal plane was 32.23∘. All of the femoral tunnel external apertures were located outside of the rectangleCONCLUSION: We evaluated the positioning of the femoral tunnel and the external aperture of the femoral tunnel with the anteromedial portal technique. This study provides a reference standard to assess accurately femoral tunnel positioning on postoperative radiographs.

Anatomic tunnel placement can be achieved with a modification to transtibial technique in single bundle anterior cruciate ligament reconstruction: A cadaver study

Placing the tunnels in the anatomic positions is important for successful restoration of knee function after anterior cruciate ligament reconstruction (ACLR). It has been shown that it is difficult to place the tunnels in the anatomic position using the transtibial technique. The purpose of this study was to evaluate the effect of each step of our modified transtibial technique (mTT) on the positioning of the femoral tunnel so as to assess whether the mTT could achieve anatomic placements of the tunnels without tibial tunnel expansion. Ten fresh-frozen cadaveric knees were used. First, the tibial tunnel was created in the center of ACL footprint. Then, a pin was inserted through the tibial tunnel using a femoral guide by four stepwise techniques: transtibial technique, additional anterior drawer force applied to the proximal tibia, another additional varus force applied to the tibia and finally, additional external rotation of the tibia and the femoral guide (mTT). Then, tibial tunnel was re-reamed using mTT with 10mm-diameter reamer. The pin positions in each technique on the femur were evaluated by the quadrant method and shapes of the tibial tunnel apertures were evaluated. Femoral pin positions in the four techniques were 23.6±4.5%, 28.4±3.4%, 30.1±3.8%, 33.2±4.5% in the superior-inferior position, and 23.9±4.3%, 26.2±3.7%, 32.0±4.3%, 36.9±4.8% in the anterior-posterior position, respectively. Pin position shifted to more inferior and posterior position with each step of mTT (all p values comparing superior-inferior and anterior-posterior positions of each step with positions of previous step were 0.008 or less). Using mTT, tibial tunnel aperture was 10.5±0.3mm wide and 12.9±1.1mm long. In conclusion, anatomic placements of femoral tunnels in ACLR without excessive tibial tunnel expansion could be achieved using the mTT.

Effects of ACL graft placement on in vivo knee function and cartilage thickness distributions

Injuries to the anterior cruciate ligament (ACL) frequently lead to early-onset osteoarthritis. Despite advancement in surgical techniques, ACL reconstruction has a limited ability to prevent these degenerative changes. While previous studies have investigated knee function after ACL reconstruction, in vivo investigations of the effects of graft placement on in vivo joint function and cartilage health are limited. This review presents a series of studies that used novel imaging and 3D modeling techniques to determine the in vivo placement of the ACL graft on the femur using two different ACL reconstruction techniques. These techniques resulted in two distinct graft placement groups: one where the ACL was placed anatomically near the center of the native ACL footprint and another where the graft was placed anteroproximally on the femur, centered outside the ACL footprint. We quantified the effects of graft placement on graft deformation during in vivo loading and how these variables affected knee motion. Finally, we quantified whether femoral placement of the graft affected cartilage thickness. Our results demonstrate that achieving anatomic graft placement on the femur is critical to restoring native ACL function and normal knee kinematics. Knees with grafts that more closely restored normal ACL function, and thus knee motion, experienced less focal cartilage thinning than did those that experienced abnormal knee motion. These results suggest that achieving anatomic graft placement is a critical factor in restoring normal knee motion and potentially slowing the development of degenerative changes after ACL reconstruction. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1160-1170, 2017.

In-out versus out-in technique for ACL reconstruction: a prospective clinical and radiological comparison

Background

Several studies have recently shown better restoration of normal knee kinematics and improvement of rotator knee stability after reconstruction with higher femoral tunnel obliquity. The aim of this study is to evaluate tunnel obliquity, length, and posterior wall blowout in single-bundle anterior cruciate ligament (ACL) reconstruction, comparing the transtibial (TT) technique and the out–in (OI) technique.

Materials and methods

Forty consecutive patients operated on for ACL reconstruction with hamstrings were randomly divided into two groups: group A underwent a TT technique, while group B underwent an OI technique. At mean follow-up of 10 months, clinical results and obliquity, length, and posterior wall blowout of femoral tunnels in sagittal and coronal planes using computed tomography (CT) scan were assessed.

Results

In sagittal plane, femoral tunnel obliquity was 38.6 ± 10.2° in group A and 36.6 ± 11.8° in group B (p = 0.63). In coronal plane, femoral tunnel obliquity was 57.8 ± 5.8° in group A and 35.8 ± 8.2° in group B (p = 0.009). Mean tunnel length was 40.3 ± 1.2 mm in group A and 32.9 ± 2.3 mm in group B (p = 0.01). No cases of posterior wall compromise were observed in any patient of either group. Clinical results were not significantly different between the two groups.

Conclusions

The OI technique provides greater obliquity of the femoral tunnel in coronal plane, along with satisfactory length of the tunnel and lack of posterior wall compromise.

Level of evidence

II, prospective study.

Anatomic Anterior Cruciate Ligament Reconstruction via Independent Tunnel Drilling: A Systematic Review of Randomized Controlled Trials Comparing Patellar Tendon and Hamstring Autografts

PURPOSE

To collect the highest level of evidence comparing anatomic anterior cruciate ligament (ACL) reconstruction via independent tunnel drilling using bone-patellar tendon-bone (BTB) and hamstring tendon (HT) autografts in terms of clinical outcome and failure rate.

METHODS

We performed a systematic review of clinical trials that randomized patients to ACL reconstruction with either BTB or HT autografts with a minimum 2-year follow-up. Only trials using independent tunnel drilling, including outside-in and anteromedial portal techniques, for both autografts were eligible for inclusion, whereas all transtibial studies were excluded. Study design, demographics, surgical technique, rehabilitation protocol, and clinical outcomes were compiled. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Quality assessment was performed using the Coleman Methodological Scale (CMS).

RESULTS

Six published studies reporting on 5 randomized controlled trials (RCTs) met the inclusion criteria. No study reported a difference in rerupture rate between BTB and HT. BTB-reconstructed knees experienced a greater incidence of anterior knee pain or crepitus in 2/7 trials and radiographic evidence of degenerative change in 3/7 trials. HT-reconstructed knees had increased instrumented laxity in 2/7 trials and less knee flexion strength postoperatively.

CONCLUSIONS

This study collects all available Level I and II evidence for anatomic ACL reconstruction using BTB and HT grafts. According to the data presented in these studies, clinical outcome scores and failure rates showed no differences for anatomic reconstruction using either autograft. However, in some studies, BTB-reconstructed knees experienced a greater incidence of anterior knee pain and radiographic evidence of degenerative change, and in others, HT-reconstructed knees had increased laxity and less knee flexion strength. In our opinion, both BTB and HT autografts remain valid options for ACL reconstruction when using anatomic drilling techniques, providing a stable knee with reliable return to activity.

LEVEL OF EVIDENCE

Level II, systematic review of Level I and II studies.

Femoral Tunnel Positioning in Anterior Cruciate Ligament Reconstruction: Anteromedial Portal versus Transtibial Technique-A Randomized Clinical Trial

Purpose  The purpose of this study was to investigate, through three-dimensional computed tomography (3D-CT), the accuracy of femoral tunnel positioning in patients undergoing anterior cruciate ligament (ACL) reconstruction, comparing transtibial (TT) and anteromedial (AM) techniques. Methods  We evaluated postoperative 3D-CT scans of 26 patients treated with ACL reconstruction with hamstrings autograft using a low accessory AM portal technique and 26 treated with the TT technique. The position of the femoral tunnel center was measured with the quadrant method. Results  Using quadrant method on CT scans, femoral tunnels were measured at a mean of 32.2 and 28.1% from the proximal condylar surface (parallel to Blumensaat line) and at a mean of 31.2 and 15.1% from the notch roof (perpendicular to Blumensaat line) for the AM and TT techniques, respectively. Conclusion  The AM portal technique provides more anatomical graft placement than TT techniques. Level of Evidence  Level I, randomized clinical study.

Joint stability after canine cranial cruciate ligament graft reconstruction varies among femoral fixation sites

OBJECTIVE

To quantify stability in cranial cruciate ligament (CrCL) deficient canine stifles with hamstring grafts affixed at 3 femoral locations.

STUDY DESIGN

Canine stifle motion study using a multi-cohort, repeated measures design.

SAMPLE POPULATION

27 canine cadaver stifles.

METHODS

Hamstring grafts (HG) were affixed at the gracilis-semitendinosus insertion and on the lateral femur (1) proximal trochlear ridge (TR), (2) craniodistal to fabella (F), or (3) condyle center (CC). Total, cranial, and caudal tibial translation and total, medial, and lateral angular displacement, with and without translational load, were quantified with the CrCL intact, transected, and reconstructed. Angular displacement was quantified from points on the distal femur and proximal tibia. Graft strain was calculated from tissue displacement measured at joint angles of 30°, 60°, 90°, and 120°.

RESULTS

Tibial translation was lowest in F constructs, which also achieved the least difference in tibial translation from intact stifles. Tibial translation was lower in intact stifles than in CrCL transected or reconstructed stifles. Less angular displacement of the proximal tibia was detected in the medial than in the lateral direction, and tibial displacement was lower in the cranial than the caudal direction. Angular displacement was lowest in the F treatment group. F constructs had the lowest graft strain at joint angles greater than 30°.

CONCLUSIONS

Femoral fixation of a canine hamstring graft craniodistal to the lateral fabella conferred the best joint stability and lowest graft strain in vitro. No fixation method restored joint stability of the intact CrCL.

Comparison of graft bending angle during knee motion after outside-in, trans-portal and trans-tibial anterior cruciate ligament reconstruction

PURPOSE

To determine graft bending angle (GBA) during knee motion after anatomic anterior cruciate ligament (ACL) reconstruction and to clarify whether surgical techniques affect GBA. Our hypotheses were that the graft bending angle would be highest at knee extension and the difference of surgical techniques would affect the bending steepness.

METHODS

Eight healthy volunteers with a mean age of 29.3 ± 3.0 years were recruited and 3D MRI knee models were created at three flexion angles (0°, 90° and 130°). Surgical simulation of the tunnel drilling was performed with anatomic tunnel position using each outside-in (OI), trans-portal (TP) and trans-tibial (TT) techniques on the identical cases. The models were matched to other knee positions and the GBA in 3D was measured using computational software. Double-bundle ACL reconstruction was analysed first, and single-bundle reconstruction was also analysed to evaluate its effect to reduce GBA. A repeated-measures ANOVA was used to compare GBA difference at three flexion angles, by three techniques or of three bundles.

RESULTS

GBA changed substantially with knee motion, and it was highest at full extension (p < 0.001) in each surgical technique. OI technique exhibited highest GBA for anteromedial bundle (94.3° ± 5.2°) at extension, followed by TP (83.1° ± 6.5°) and TT (70.0° ± 5.2°) techniques (p < 0.01). GBA for posterolateral bundle at extension were also high in OI (84.6° ± 7.4°), TP (83.0° ± 6.3°) and TT (77.2° ± 7.0°) techniques (n.s.). Single-bundle grafts did not decrease GBA compared with double-bundle grafts. In OI technique, a more proximal location of the femoral exit reduced GBA of each bundle at extension and 90° flexion.

CONCLUSION

A significant GBA change with knee motion and considerably steep bending at full extension, especially with OI and TP techniques, were simulated. Although single-bundle technique did not reduce GBA as seen in double-bundle technique, proximal location of femoral exits by OI technique, with tunnels kept in anatomic position, was effective in decreasing GBA at knee extension and flexion. For clinical relevance, high stress on graft and bone interface has been suggested by steep GBA at full extension after anatomic ACL reconstruction.

LEVEL OF EVIDENCE

Therapeutic study (prospective comparative study), Level II.

Comparison of femur tunnel aperture location in patients undergoing transtibial and anatomical single-bundle anterior cruciate ligament reconstruction

PURPOSE

Although three-dimensional computed tomography (3D-CT) has been used to compare femoral tunnel position following transtibial and anatomical anterior cruciate ligament (ACL) reconstruction, no consensus has been reached on which technique results in a more anatomical position because methods of quantifying femoral tunnel position on 3D-CT have not been consistent. This meta-analysis was therefore performed to compare femoral tunnel location following transtibial and anatomical ACL reconstruction, in both the low-to-high and deep-to-shallow directions.

METHODS

This meta-analysis included all studies that used 3D-CT to compare femoral tunnel location, using quadrant or anatomical coordinate axis methods, following transtibial and anatomical (AM portal or OI) single-bundle ACL reconstruction.

RESULTS

Six studies were included in the meta-analysis. Femoral tunnel location was 18 % higher in the low-to-high direction, but was not significant in the deep-to-shallow direction, using the transtibial technique than the anatomical methods, when measured using the anatomical coordinate axis method. When measured using the quadrant method, however, femoral tunnel positions were significantly higher (21 %) and shallower (6 %) with transtibial than anatomical methods of ACL reconstruction.

CONCLUSION

The anatomical ACL reconstruction techniques led to a lower femoral tunnel aperture location than the transtibial technique, suggesting the superiority of anatomical techniques for creating new femoral tunnels during revision ACL reconstruction in femoral tunnel aperture location in the low-to-high direction. However, the mean difference in the deep-to-shallow direction differed by method of measurement.

LEVEL OF EVIDENCE

Meta-analysis, Level II.

Optimal entry position on the lateral femoral surface for outside-in drilling technique to restore the anatomical footprint of anterior cruciate ligament

PURPOSE

To investigate the optimal starting points for drilling on the lateral femoral condyle for better coverage of the anatomical footprint of the anterior cruciate ligament (ACL) using the outside-in (OI) technique in a single-bundle ACL reconstruction.

METHODS

Femoral tunnel drilling was simulated on three-dimensional bone models from 40 subjects by connecting the centre of the ACL footprint with various points on the lateral femoral surface. The percentage of the femoral footprint covered by apertures of the virtual tunnel sockets with 9 mm diameter was calculated for each tunnel.

RESULTS

The mean percentages of the femoral footprint covered by the apertures of the virtual tunnel sockets were significantly higher when drilled at 2 and 3 cm from the lateral epicondyle on a 45° line and a 60° line anterior from the proximal-distal axis than the other points. However, articular cartilage damage was occurred in nine subjects at 3 cm on a 60° line and eight subjects at 3 cm on a 45° line. Posterior wall blowout occurred in five subjects at 3 cm on a 45° line. Thus, OI drilling at 3 cm from the epicondyle has a risk of these complications.

CONCLUSION

During the OI drilling of the femoral tunnel, connecting the centre of the anatomical footprint of the ACL and the entry drilling point at 2 cm from the lateral epicondyle on between the 45° line and the 60° line anterior from the proximal-distal axis provides an oval-shaped socket aperture that covers and restores the native ACL footprint as nearly as possible.

LEVEL OF EVIDENCE

III.

Reliability of 3-Dimensional Computed Tomography for Application of the Bernard Quadrant Method in Femoral Tunnel Position Evaluation After Anatomic Anterior Cruciate Ligament Reconstruction

PURPOSE

To validate whether the Bernard quadrant method, which was developed for application on simple lateral radiography, can be used with 3-dimensional computed tomography (3D CT) to localize the femoral insertion of the reconstructed anterior cruciate ligament (ACL).

METHODS

We analyzed 32 knees with ACL tears that were reconstructed using a metal interference screw for fixation at the femoral tunnel between March 2012 and May 2013. Postoperative lateral radiographs and 3D CT images were obtained 7 days after the operation. By use of the Bernard quadrant method, the location of the femoral tunnel was measured by 2 orthopaedic surgeons by locating the position of the metal interference screw using 3D CT imaging and simple lateral knee radiography. The correlation between the femoral tunnels on the 2 radiographic images was compared using the MedCalc statistical analysis program.

RESULTS

On the 3D CT image, the position of the femoral insertion of the ACL as measured by the position of the metal screw head was 36.3% ± 6.0% in the x-coordinate and 39.6% ± 9.1% in the y-coordinate compared with 37.6% ± 5.8% and 41.0% ± 11.6%, respectively, on the simple radiograph. The Pearson correlation coefficients between 3D CT and simple radiography were 0.840 for the x-coordinate and 0.858 for the y-coordinate. Intraobserver reliability and interobserver reliability for both coordinates were greater than 0.9 on 3D CT.

CONCLUSIONS

Application of the Bernard quadrant method on 3D CT showed high correlation to the originally described method using lateral radiographs and can be used reliably for localizing the reconstructed ACL.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Anatomic Tunnel Placement in Anterior Cruciate Ligament Reconstruction

The anatomic anterior cruciate ligament (ACL) reconstruction concept has developed in part from renewed interest in the insertional anatomy of the ACL, using surgical techniques that can reproduce this anatomy reliably and accurately during surgical reconstruction. Several technical tools are available to help identify and place the tibial and femoral grafts anatomically, including arthroscopic anatomic landmarks, a malleable ruler device, and intraoperative fluoroscopy. The changes in technique for anatomic tunnel placement in ACL reconstruction follow recent biomechanical and kinematic data that demonstrate improved time zero characteristics. A better re-creation of native ACL kinematics and biomechanics is achieved with independent femoral drilling techniques that re-create a central footprint single-bundle ACL reconstruction or double-bundle reconstruction. However, to date, limited short-term and long-term clinical outcome data have been reported that support using either of these techniques rather than a transtibial drilling technique. This lack of clear clinical advantage for femoral independent and/or double-bundle techniques may arise because of the potentially offsetting biologic incorporation challenges of these grafts when placed using these techniques or could result from modifications made in traditional endoscopic transtibial techniques that allow improved femoral and tibial footprint restoration.

Height and Depth Guidelines for Anatomic Femoral Tunnels in Anterior Cruciate Ligament Reconstruction: A Cadaveric Study

PURPOSE

To develop guidelines for femoral tunnel placement based on height and depth on the lateral wall of the notch and to apply these guidelines arthroscopically to show tunnel placements within the anterior cruciate ligament (ACL) femoral insertion site.

METHODS

Twelve cadaveric knees were dissected to define the centers of the femoral ACL attachment and its anteromedial (AM) and posterolateral (PL) bundles. In 90° of flexion, the height and depth of each center were determined relative to the low point on the lateral intercondylar notch. Radiographic grid measurements were made to validate these measurements. Subsequently, the measurement guidelines were applied arthroscopically in 10 new cadaveric knees to evaluate their accuracy for an anatomic single-bundle femoral tunnel. Interobserver reliability analysis was evaluated with the intraclass correlation coefficient.

RESULTS

In 90° of flexion, the height of the ACL center was 8.7 ± 0.6 mm from the low point of the lateral notch; PL center, 7.2 ± 1.2 mm; and AM center, 9.6 ± 1.1 mm. Relative to the low point, the ACL center was 1.7 ± 1.7 mm posterior, the PL center was 3.4 ± 1.5 mm anterior, and the AM center was 4.9 ± 1.7 mm posterior (intraclass correlation coefficient, 0.859). Radiographic grid measurements were consistent with the direct measurements. Application of the guidelines arthroscopically with or without the assistance of a 7-mm offset aimer placed all guide pins for tunnels within the femoral ACL footprint, with 90% within 4 mm of the ACL center.

CONCLUSIONS

This study showed in cadaveric knees in 90° of flexion that the center of the ACL can be located on the lateral notch at a height of 8.7 ± 0.6 mm from the lowest point and anterior 11.5 ± 1.3 mm from the deepest point. How anatomic tunnels can be placed using these measurements was also shown in cadaveric knees.

CLINICAL RELEVANCE

An anatomic femoral tunnel for ACL reconstruction can be placed using height and depth guidelines.

Comparison of Femoral Tunnel Length and Obliquity Between Transtibial, Anteromedial Portal, and Outside-In Surgical Techniques in Single-Bundle Anterior Cruciate Ligament Reconstruction: A Meta-analysis

PURPOSE

It is unclear whether femoral tunnel length and obliquity differ after transtibial and independent femoral drilling techniques of anterior cruciate ligament (ACL) reconstruction. This meta-analysis therefore compared femoral tunnel length and obliquity in patients who underwent ACL reconstruction by the transtibial, anteromedial (AM) portal, and outside-in (OI) techniques.

METHODS

In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, all studies comparing femoral tunnel length and obliquity with various measurement tools-from direct measurement to imaging methods such as plain radiography, computed tomography, or magnetic resonance imaging-in patients who underwent reconstruction by the transtibial or independent femoral drilling (AM portal or OI) techniques were included.

RESULTS

Fourteen studies were included in the meta-analysis. The femoral tunnel length was 7.8 to 11.0 mm longer (P < .05) and coronal obliquity was 7.5° to 29.1° more vertical (P < .05) with the transtibial technique than with the AM portal or OI technique. Femoral tunnel and graft obliquity in the sagittal plane, however, did not differ significantly (P > .05).

CONCLUSIONS

ACL reconstruction using the AM portal and OI femoral drilling techniques resulted in a shorter length and greater coronal obliquity of the femoral tunnel than did the transtibial technique. However, these 3 femoral drilling techniques resulted in similar obliquities of the femoral tunnel and graft in the sagittal plane.

LEVEL OF EVIDENCE

Level III, meta-analysis.

Measurements of tunnel placements after anterior cruciate ligament reconstruction--A comparison between CT, radiographs and MRI

BACKGROUND

A non-anatomic placement of the femoral and tibial tunnels may affect outcome in anterior cruciate ligament (ACL) reconstructions. Tunnel placements are validated with varying imaging modalities. We compared measurements of tunnel placements between radiographs, computed tomography (CT) and magnetic resonance imaging (MRI) in a clinical setting, assessed the reliability and aimed to decide on a possible "gold standard".

METHODS

All patients who had undergone at least two of three modalities, radiographs, MRI and CT, after ACL reconstruction between January 2011 and June 2013 were included. Two radiologists measured tunnel placements according to a standardized protocol. Interobserver agreement was assessed with intraclass correlation coefficients (ICC), the intermodality differences with Bland-Atman plots. Radiation data for CT studies were collected.

RESULTS

Forty-six CTs, 45 radiographs and 30 MRIs were reviewed. Femoral inter-observer agreement for radiographs was ICC=0.64, for CT ICC=0.86 and for MRI ICC = 0.75. Tibial inter-observer agreement for radiographs was ICC=0.92, for CT-mip ICC=0.91, for CT and MRI ICC = 0.87. No intermodality differences between the femoral measurements were observed. In the tibia, there were differences between radiographs and CT (-3.9%), radiographs-MRI (-3.6%), CT-CT mip (3.2%) and CTmip-MRI (-3.1%). The effective radiation doses varied between 0.025 and 0.045 mSv, mean and median was 0.033 mSv.

CONCLUSION

There were differences in the tibial measurements between summation and single slice images. Only 3D-CT depicted the femoral tunnel in both directions. CT was consistently reliable in both femoral and tibial measurements. Effective radiation dose from CT was lower than previously reported. CT can safely be used in routine clinical practice to evaluate tunnel placements after ACL reconstruction.

Does flexible tunnel drilling affect the femoral tunnel angle measurement after anterior cruciate ligament reconstruction?

PURPOSE

To quantify the mean difference in femoral tunnel angle (FTA) as measured on knee radiographs between rigid and flexible tunnel drilling after anatomic anterior cruciate ligament (ACL) reconstruction.

METHODS

Fifty consecutive patients that underwent primary anatomic ACL reconstruction with a single femoral tunnel drilled with a flexible reamer were included in this study. The control group was comprised of 50 patients all of who underwent primary anatomic ACL reconstruction with a single femoral tunnel drilled with a rigid reamer. All femoral tunnels were drilled through a medial portal to ensure anatomic tunnel placement. The FTA was determined from post-operative anterior-to-posterior (AP) radiographs by two independent observers. A 5° difference between the two mean FTA was considered clinically significant.

RESULTS

The average FTA, when drilled with a rigid reamer, was 42.0° ± 7.2°. Drilling with a flexible reamer resulted in a mean FTA of 44.7° ± 7.0°. The mean difference of 2.7° was not statistically significant. The intraclass correlation coefficient for inter-tester reliability was 0.895.

CONCLUSIONS

The FTA can be reliably determined from post-operative AP radiographs and provides a useful and reproducible metric for characterizing femoral tunnel position after both rigid and flexible femoral tunnel drilling. This has implications for post-operative evaluation and preoperative treatment planning for ACL revision surgery.

LEVEL OF EVIDENCE

IV.

A randomized prospective controlled study with 5-year follow-up of cross-pin femoral fixation versus metal interference screw fixation in anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to determine and compare mid- to long-term results of cross-pin versus metal interference screw fixation of ACL graft.

METHODS

In a prospective trial, 62 patients were randomized into two groups based on method of fixation. Transtibial drilling technique was used in the cross-pin and outside-in femoral drilling in the interference screw fixation group. Clinical and radiographical outcomes were assessed 2 and 5 years postoperatively.

RESULTS

The study showed no clinically significant difference with respect to method of graft fixation. Mean anteroposterior side-to-side instrumented laxity difference was 2.4 mm in the cross-pin group and 2.5 mm in the screw group (n.s.). Median Tegner and mean Lysholm scores at 5 years were 6 (range 3-9) and 92.2 (range 69-100) in the screw group and 7 (3-10) and 93.3 (82-100), respectively, in the cross-pin group. Radiographical osteoarthritis increased in both groups from 2 to 5 years after reconstruction (p < 0.05), especially in the medial and patellofemoral joint spaces. Widening of the drill tunnels continued from 2 to 5 years without clinical significance.

CONCLUSIONS AND CLINICAL RELEVANCE

The method of graft fixation did not yield a difference in clinical or radiographical outcome at 5 years. Results were excellent in both groups.

LEVEL OF EVIDENCE

I.

How accurate are anatomic landmarks for femoral tunnel positioning in anterior cruciate ligament reconstruction? An in vivo imaging analysis comparing both anteromedial portal and outside-in techniques

PURPOSE

To assess the ability of 2 independent surgical techniques, an inside-out technique and an outside-in technique, using bony landmarks on the femoral wall, to place the anterior cruciate ligament graft anatomically.

METHODS

A retrospective single-center study was conducted in 2012 and included patients who underwent anterior cruciate ligament reconstruction. Two techniques were used: The lateral condylar wall was visualized from the anterolateral portal and tunnels were drilled "outside-in" in one group, whereas viewing was performed from the anteromedial portal and retrograde drilling ("inside-out") was performed in the other group. The primary outcome measure was the placement of the tunnel center point on postoperative computed tomography scans with 3-dimensional reconstruction, according to the radiographic quadrant method of Bernard and Hertel. The measurements were compared with optimal placements according to Bird et al. Their reliability was assessed with Spearman (rho) and intraclass correlation coefficients.

RESULTS

Forty patients were included, with 20 in each group; the mean age was 29.8 ± 9.6 years, and there were 33 men and 7 women. The interobserver reliability and intraobserver reliability of measurements were good, with a Spearman ρ between 0.46 (P = .002) and 0.93 (P < .001) and an intraclass correlation coefficient between 0.44 (P = .001) and 0.86 (P < .001). The femoral tunnel positions of both techniques were close to the previously published anatomic placements, but there was a significant difference between our results and the theoretical position in proximal-distal measurements (P = .01). There was no difference in the anteroposterior measurements. There was no statistical difference in the accuracy of placement of the femoral tunnel center point between these 2 independent techniques.

CONCLUSIONS

The direct arthroscopic visualization of bony landmarks seems sufficient for accurate positioning of the femoral tunnel whatever the drilling technique. This finding is clinically relevant because the routine use of direct measurement techniques or intraoperative radiographs may not be necessary to obtain anatomic tunnel placement.

LEVEL OF EVIDENCE

Level IV, case series.

Direct Visualization of Existing Footprint and Outside-In Drilling of the Femoral Tunnel in Anterior Cruciate Ligament Reconstruction in the Knee

Improper femoral tunnel placement in anterior cruciate ligament (ACL) reconstruction is a significant problem and may be a cause of ACL graft failure and abnormal kinematics, which may lead to late degenerative changes after reconstruction. Recently, there has been concern that the transtibial approach may contribute to nonanatomic placement of the femoral tunnel, resulting in abnormal knee kinematics. Tibial-independent techniques can provide more anatomic placement of the ACL graft, but these can be technically demanding. This technical note describes the senior author's technique to directly identify the femoral ACL remnant and use the center of the femoral ACL footprint and retrograde drilling to create an anatomic femoral socket for single-bundle reconstruction. This technique provides femoral tunnel placement based on identification of a patient-specific ACL footprint instead of averaged anatomic measurements from large groups. This technique has been shown to produce anatomic ACL graft position and orientation and restore more normal knee kinematics.

Influences of knee flexion angle and portal position on the location of femoral tunnel outlet in anterior cruciate ligament reconstruction with anteromedial portal technique

PURPOSE

To evaluate the influences of knee flexion angle and portal position on the location of femoral tunnel outlet in anterior cruciate ligament (ACL) reconstruction with the anteromedial (AM) portal technique.

METHODS

We recruited 6 volunteers with 12 normal knees. Each knee was flexed 120° or 135° and scanned with an open MRI. A 3D knee model was created. Virtual femoral tunnels were created on the footprint of the AM bundle and the posterolateral (PL) bundle of the ACL from three arthroscopic portals: the standard AM portal, the far medial and low portal, and the far medial and high (FMH) portal. The location of the femoral tunnel outlet was evaluated by comparing to the dissected cadaveric knee.

RESULTS

Both increased flexion angle and lowering the drilling portal have a similar influence on the femoral tunnel outlet by moving them anterior and distally. Medialization of the portal moves them posteriorly and distally. PL tunnels created on the 120° knee model are more likely to be located under the lateral head of the gastrocnemius especially when they are drilled through the AM or FMH portals.

CONCLUSION

If the femoral tunnel outlet is located under the soft tissue such as gastrocnemius attachment, suspension fixation devices may lapse into fixation failure by sitting on the soft tissue rather than the cortex bone surface. It is more desirable to drill in 135° knee flexion rather than 120°, and through a lower portal, to avoid creating the femoral tunnel outlet under soft tissues.

Comparison of the Modified Transtibial Technique, Anteromedial Portal Technique and Outside-in Technique in ACL Reconstruction

Purpose

To compare clinical and radiographic results of anterior cruciate ligament (ACL) reconstruction using modified transtibial technique (mTT), anteromedial (AM) portal technique and outside-in (OI) technique.

Materials and Methods

From March 2007 to December 2012, ACL reconstruction was performed using the mTT, AM portal technique and OI technique in 20 patients each. Anteroposterior and rotational stability were assessed using the GNRB arthrometer and pivot-shift test. Femoral tunnel obliquity was measured on the anteroposterior and lateral radiographs.

Results

Tegner score, Lysholm score, International Knee Documentation Committee score, pivot-shift test were improved at final follow-up in all three groups. However, statistical difference was not shown. Side-to-side difference in GNRB arthrometer was average of 1.4 mm, 1.0 mm and 0.9 mm in mTT, AM and OI group, showing the signicant difference between mTT and AM/OI groups (p<0.001). The mean femoral tunnel obliquity was 56.4° in the mTT group, 39.4° in the AM group and 33.6° in the OI group, showing significant intergroup difference (p<0.001). It showed the significant difference among three groups (p<0.001).

Conclusions

Clinical results were improved in all three groups. Femoral tunnel obliquity in AM and OI were more horizontal on the coronal plane. They are thought to have more benefits in oblique positioning of the grafted ACL in rotational stability; however, there was no significant difference among three techniques in pivot-shift test to assess the rotational stability in this study.

Creation of femoral tunnel by outside-in technique for ACL reconstruction: an analysis

PURPOSE

To study the outcome of ACL reconstruction by retrograde outside-in (OI) creation of femoral tunnel.

METHODS

ACL reconstruction was done in 41 cases by OI technique. The tip of 115° femoral guide was placed at posterior aspect of femoral foot print of ACL. Reaming was done from outside-in over guide pin. The length of femoral tunnel was obtained by measuring guide pin. The location of intra-articular femoral tunnel aperture and graft was recorded. Tibial tunnel was created with 50° guide placed at tibial foot print of ACL. Post-operative digital radiograph was taken. Antero-posterior view was used to calculate coronal inclination of femoral tunnel. On lateral view femoral tunnel location was marked in relation to the intersection of Blumensaat line and posterior femoral cortical line. Lysholm scoring and pivot shift test were performed at follow-up. Objective measurement of anterior tibial translation was done by rolimeter (aircast) at 1 year.

RESULTS

The mean femoral tunnel length recorded was 39.5 mm (±3.4). There was no incidence of femoral tunnel blow out or graft impingement. All cases had femoral tunnel aperture location posterior to posterior femoral cortical line and inferior to Blumensaat line. The mean coronal angle of femoral tunnel was 30.39° (±4.6). The mean preoperative Lysholm score of 53.5 (±13) increased to 95.2 (±3.5) 1 year after surgery. All the patients had full range of motion. The pivot shift test was negative and instrumented measurement of anterior translation of tibia was near normal in all cases.

CONCLUSION

OI technique of ACL reconstruction is a simple reproducible technique. The unconstrained placement and angling of femoral guide result in a femoral tunnel which is through footprint of ACL. The graft is placed very low, oblique and as posterior as possible on femoral side mimicking the native ACL.

LEVEL OF EVIDENCE

III.