Comparison of 3-dimensional obliquity and anisometric characteristics of anterior cruciate ligament graft positions using surgical navigation

Anatomic femoral tunnel and satisfactory clinical outcomes achieved with the modified transtibial technique in anterior cruciate ligament reconstruction: A systematic review and meta-analysis

Background

Anatomic anterior cruciate ligament (ACL) reconstruction is considered the gold standard treatment for ACL injuries because it aims to restore the knee's normal anatomy and stability, while also protecting long-term knee health. Long-term clinical and radiological outcomes after ACL reconstruction using the modified TT technique are unclear.

Objective

To assess the clinical and radiological outcomes following ACL reconstruction using modified transtibial (TT) techniques at a minimum 12-month follow-up.

Design

A systematic review with meta-analysis.

Methods

PubMed, EMBASE, Web of Science, the Cochrane Library, and MEDLINE databases were searched from the inception to December 1, 2022. PICO search strategy was used to identify studies applying modified TT techniques on patients with ACL reconstruction and a minimum follow-up of 12 months. Eligible studies were identified independently by two reviewers. We extracted data on patient demographics, surgical characteristics, patient reported outcomes including subjective evaluations and clinical outcomes. Radiological data including femoral and tibial tunnel position, femoral and tibial tunnel length, and femoral tunnel angle were also extracted. The tunnel position was evaluated using the quadrant method based on three-dimensional computed tomography (3D CT) images. The standardized mean difference (SMD) and 95 % confidence interval (CI) were calculated for clinical and radiological outcomes.

Results

Sixteen studies involving 628 patients were finally included. The SMD of Lysholm (90.39; 95 % CI 83.41-97.38), IKDC (86.07; 95 % CI 79.84-92.31), and Tegner (6.15; 95 % CI 3.96-8.33) scores were considered satisfactory. The depth of the femoral tunnel showed a pooled SMD of 30.08 % (95 % CI 28.25-31.91 %), and the height showed a pooled SMD of 37.72 % (95 % CI 35.75-39.70 %). The pooled SMD for the femoral tunnel angle in the coronal plane was 48.27°(95 % CI 43.14-53.40°), and the pooled SMD for the femoral tunnel length was 33.98 mm (95 % CI 29.03-38.93 mm).

Conclusions

This investigation has shown that modified TT technique can create an anatomic femoral tunnel and maintain optimal tunnel length and angulation. Most patients had satisfactory subjective outcomes and physical examinations after ACL reconstruction using modified TT technique. This information may assist in guiding expectations of clinicians and patients following ACL reconstruction with modified TT technique.

Isometry of anteromedial reconstructions mimicking the deep medial collateral ligament depends on the femoral insertion

PURPOSE

This study aimed to investigate the length change patterns of the native deep medial collateral ligament (dMCL) and potential anteromedial reconstructions (AMs) that might be added to a reconstruction of the superficial MCL (sMCL) to better understand the control of anteromedial rotatory instability (AMRI).

METHODS

Insertion points of the dMCL and potential AM reconstructions were marked with pins (tibial) and eyelets (femoral) in 11 cadaveric knee specimens. Length changes between the pins and eyelets were then tested using threads in a validated kinematics rig with muscle loading of the quadriceps and iliotibial tract. Between 0° and 100° knee flexion, length change pattern of the anterior, middle and posterior part of the dMCL and simulated AM reconstructions were analysed using a rotary encoder. Isometry was tested using the total strain range (TSR).

RESULTS

The tibiofemoral distance of the anterior dMCL part lengthened with flexion (+12.7% at 100°), whereas the posterior part slackened with flexion (-12.9% at 100°). The middle part behaved almost isometrically (maximum length: +2.8% at 100°). Depending on the femoral position within the sMCL footprint, AM reconstructions resulted in an increase in length as the knee flexed when a more centred position was used, irrespective of the tibial attachment position. Femoral positioning in the posterior aspect of the sMCL footprint exhibited <4% length change and was slightly less tight in flexion (min TSR = 3.6 ± 1.5%), irrespective of the tibial attachment position.

CONCLUSION

The length change behaviour of potential AM reconstructions in a functionally intact knee is mainly influenced by the position of the femoral attachment, with different tibial attachments having a minimal effect on length change. Surgeons performing AM reconstructions to control AMRI would be advised to choose a femoral graft position in the posterior part of the native sMCL attachment to optimise graft length change behaviour. Given the high frequency of MCL injuries, sufficient restoration of AMRI is essential in isolated and combined ligamentous knee injuries.

LEVEL OF EVIDENCE

There is no level of evidence as this study was an experimental laboratory study.

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.

Race and Gender Differences in Anterior Cruciate Ligament Femoral Footprint Location and Orientation: A 3D-MRI Study

OBJECTIVE

The femoral tunnel position is crucial to anatomic single-bundle anterior cruciate ligament (ACL) reconstruction, but the ideal femoral footprint position are mostly based on small-sized cadaveric studies and elderly patients with a single ethnic background. This study aimed to identify potential race- or gender-specific differences in the ACL femoral footprint location and ACL orientation, determine the correlation between the ACL orientation and the femoral footprint location.

METHODS

Magnetic resonance images (MRIs) of 90 Caucasian participants and 90 matched Chinese subjects were used for reconstruction of three-dimensional (3D) femur and tibial models. ACL footprints were sketched by several experienced orthopedic surgeons on the MRI photographs. The anatomical coordinate system was applied to reflect the ACL footprint location and orientation of scanned samples. The femoral ACL footprint locations were represented by their distance from the origin in the anteroposterior (A/P) and distal-proximal (D/P) directions. The orientation of the ACL was described with the sagittal, coronal and transverse deviation angles. The ACL orientation and femoral footprint position were compared by the two-sided t-test. Multiple regression analysis was used to study the correlation between the orientation and femoral footprint position.

RESULTS

The average femur footprint A/P position was -6.6 ± 1.6 mm in the Chinese group and -5.1 ± 2.3 mm in the Caucasian group, (p < 0.001). The average femur footprint D/P position was -2.8 ± 2.4 mm in Chinese and - 3.9 ± 2.0 mm in Caucasians, (p = 0.001). The Chinese group had a mean difference of a 1.5 mm (6.1%) more posterior and 1.1 mm (5.3%) more proximal in the position from the flexion-extension axis (FEA). And the males have a sagittal plane elevation about 4-5° higher than females in both racial groups. Furthermore, for every 1% (0.40 mm) increase in A/P and D/P values, the sagittal angle decreased by about 0.12° and 0.24°, respectively; the coronal angle decreased by about 0.10° and 0.30°, respectively. For every 1% (0.40 mm) increase in D/P value, the transverse angle increased by about 0.14°.

CONCLUSION

The significant race- and gender-specific differences in the femoral footprint and orientation of the ACL should be taken in consideration during anatomic single-bundle ACL reconstruction. Furthermore, the quantitative relationship between the ACL orientation and the footprint location might provide some reference for surgeons to develop a surgical strategy in ACL single-bundle reconstruction and revision.

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.

No differences in clinical outcomes and graft healing between anteromedial and central femoral tunnel placement after single bundle ACL reconstruction

PURPOSE

The purpose of this study was to compare clinical outcomes and graft healing after anterior cruciate ligament (ACL) reconstruction with anteromedial and central femoral tunnel placement.

METHODS

During 2016 and 2018, 110 consecutive patients underwent single bundle ACL reconstruction; 85 patients met the inclusion criteria, and each patient underwent 3D-CT within 1 week and MRI 1.5 years after the operation. The central point of the femoral tunnel and signal/noise quotient (SNQ) of three regions of interest (ROI) in the intra-articular graft were measured to analyse the tunnel position and graft healing extent. Clinical assessments, including functional scores, KT-2000 arthrometer measurements and pivot-shift tests, were evaluated at the 2-year follow-up. Patients were divided into two groups depending on the femoral tunnel position: the anteromedial position group (Group A) and the centre position group (Group B).

RESULTS

Seventy-one patients were available for the 2-year follow-up and MRI examination: 34 patients in Group A and 35 patients in Group B, and 2 patients were excluded for an eccentric tunnel position. No graft failure occurred, and compared with the preoperative assessment outcomes, the outcomes of both groups improved at the final follow-up. Group A was significantly better than Group B regarding the KT-2000 arthrometer measurements (P = 0.031). No significant differences were observed in terms of functional scores, pivot-shift test results, or the SNQ between groups.

CONCLUSIONS

No differences in clinical outcomes or graft healing were found between AM and central femoral tunnel placements in single bundle ACL reconstruction. Therefore, satisfactory clinical outcomes, knee stability and graft healing can be obtained for both femoral tunnel placements.

LEVEL OF EVIDENCE

II.

Creating a Femoral Tunnel Aperture at the Anteromedial Footprint Versus the Central Footprint in ACL Reconstruction: Comparison of Contact Stress Patterns

Background:

It remains unclear whether an anteromedial (AM) footprint or a central footprint anterior cruciate ligament (ACL) graft exhibits less contact stress with the femoral tunnel aperture. This contact stress can generate graft attrition forces, which can lead to potential graft failure.

Purpose/Hypothesis:

The purpose of this study was to compare the difference in contact stress patterns of the graft around a femoral tunnel that is created at the anatomic AM footprint versus the central footprint. It was hypothesized that the difference in femoral tunnel positions would influence the contact stress at the interface between the reconstructed graft and the femoral tunnel orifice.

Study Design:

Controlled laboratory study.

Methods:

A total of 24 patients who underwent anatomic single-bundle ACL reconstruction were included in this study. In 12 patients, the femoral tunnels were created at the center of the native AM footprint (AM group), and in the remaining 12 patients the center of the femoral tunnel was placed in the anatomic central footprint (central group). Three-dimensional knee models were created and manipulated using several modeling programs, and the graft-tunnel angle (GTA) was determined using a special software program. The peak contact stresses generated on the virtual ACL graft around the femoral tunnel orifice were calculated using a finite element method.

Results:

The mean GTA was significantly more obtuse in the AM group than in the central group (124.2° ± 5.9° vs 112.6° ± 7.9°; P = .001). In general, both groups showed high stress distribution on the anterior surface of the graft, which came in contact with the anterior aspect of the femoral tunnel aperture. The degree of stress in the central group (5.3 ± 2.6 MPa) was significantly higher than that in the AM group (1.2 ± 1.1 MPa) (P < .001).

Conclusion:

Compared with the AM footprint ACL graft, the central footprint ACL graft developed significantly higher contact stress in the extended position, especially around the anterior aspect of the femoral tunnel orifice.

Clinical Relevance:

The contact stress of the ACL graft at the extended position of the knee may be minimized by creating the femoral tunnel at the AM-oriented footprint.

Computer-Assisted Orthopedic and Trauma Surgery

BACKGROUND

There are many ways in which computer-assisted orthopedic and trauma surgery (CAOS) procedures can help surgeons to plan and execute an intervention.

METHODS

This study is based on data derived from a selective search of the literature in the PubMed database, supported by a Google Scholar search.

RESULTS

For most applications the evidence is weak. In no sector did the use of computer-assisted surgery yield any relevant clinical or functional improvement. In trauma surgery, 3D-navigated sacroiliac screw fixation has become clinically established for the treatment of pelvic fractures. One randomized controlled trial showed a reduction in the rate of screw misplacement: 0% with 3D navigation versus 20.4% with the conventional procedure und 16.6% with 2D navigation. Moreover, navigation-assisted pedicle screw stabilization lowers the misplacement rate. In joint replacements, the long-term results showed no difference in respect of clinical/functional scores, the time for which the implant remained in place, or aseptic loosening.

CONCLUSION

Computer-assisted procedures can improve the precision of certain surgical interventions. Particularly in joint replacement and spinal surgery, the research is moving away from navigation in the direction of robotic procedures. Future studies should place greater emphasis on clinical and functional results.

Flexion deformity and laxity as a function of knee position at the time of tensioning of rigid anatomic hamstring ACL grafts

Background

Anatomic ACL grafts routinely display the anisometric length-tension behaviour seen in the native ligament with maximum length in full knee extension. Recent improvements in hamstring graft preparation and fixation have improved graft rigidity to the point where total graft lengthening after implantation may be less than 1 mm. Despite this it remains common practice to fix these grafts in a knee flexed position.

Methods

Nineteen participants underwent all-inside ACL reconstruction with optimally preconditioned 4 strand semitendinosus grafts using bi-cortical adjustable suspensory loop fixation. Using a computer navigation system, baseline measures of anisometricity, extension range, and tibial rotation were made. The graft was tensioned and provisionally fixed with the knee flexed 5° beyond its anisometric point and extension range recorded. The graft was then definitively fixed with the knee fully extended and extension range and tibial rotation recorded again. Anterior laxity measurements were made pre-operatively and postoperatively using a manual arthrometer and compared to those from the contralateral limb.

Results

Fixing the graft with the knee flexed produced a mean FD of 10.9° (p < 0.0001) and fixing in extension restored full extension (p = 0.661). Fixing in extension restored anterior laxity at 30° (p = 0.224) and at 90° (p = 0.668). There were very strong correlations between post-operative and control extension range (r = 0.931, p < 0.0001) and anterior laxity and 30° (r = 0.830, p < 0.0001) measures. Constraint of tibial internal rotation increased by 2.9° during the pivot-shift (p < 0.001) and increased with pivot shift grade (r = 0.474, p = 0.040).

Conclusion

Fixing rigid anatomic hamstring grafts in a knee flexed position routinely produces a flexion deformity. Tensioning and fixing grafts with the knee fully extended restores full extension and anterior laxity at 30° and 90°. Rotational constraint is significantly improved and correlates with the pivot-shift grade.

Clinical relevance

Rigid anatomic grafts should be tensioned and fixed with the knee fully extended.

A comparative study of a new "off-centre:off-centre" technique of transtibial ACL reconstruction with "centre:centre" transportal ACL reconstruction

BACKGROUND & INTRODUCTION

A Single Bundle ACL Reconstruction aims at placing Tibial and Femoral attachment sites of graft from Centre of Native Tibial Foot-print to Centre of Native Femoral Footprint. In tibial tunnel independent Transportal Reconstruction, where the two points are chosen separately, the objective is easily achievable. In Tibial tunnel dependent Transtibial ACL reconstruction, Capture of Centre of femoral tunnel is dictated by Trajectory of Tibial Tunnel. Heming et al. remarked that a TT technique could produce tunnel centred in the both the tibial and femoral footprint but only if a starting point "prohibitively close" to the joint line with a correspondingly short tibial tunnel were used. A new technique wherein authors aim to place the mouths of Tibial & Femoral tunnel at off-centre location, taking care to contain these tunnels still within native footprints to achieve a tunnel which is of adequate length and does not come too close to the joint and saves MCL from violation.

OBJECTIVE

To study the clinic-radiological outcome of a new "Off-centre to Off-centre" method of Transtibial Reconstruction and compare the results with "centre to centre" method of Transportal reconstruction.

METHODS

A prospective randomised comparative study of consecutive 75 clinico-radiological cases of ACL tear with definitive clinical symptoms of knee instability who underwent arthroscopic ACL reconstruction by Same Arthroscopy Surgeon was conducted between 2016 and 2018. A modification, as described herein below, was used in Transtibial technique with placement of centre of mouth of internal opening of tibial tunnel "off-centre" that allowed a predictable capture of Femoral Footprint in "off-centre" location without tunnel being too close to joint line. Only those cases were included in which the mouths of tunnel were completely contained within footprints. Capture of footprints was verified during arthroscopy. 11 cases were excluded because either the native footprint was not clearly delineated, or surgeon failed to completely contain the mouth of tunnel/socket within the delineated footprint of tibia or femur. Hence 64 patients, 32 each in Transtibial & Transportal group were enrolled into the study. The results were analysed with the objective to arrive at recommendations for improving capture of anatomical footprints at both ends by Transtibial technique.

RESULTS

There were no statistically significant differences in Clinical outcome scores. However there were statistically significant differences in length of Femoral Tunnel, Obliquity of Femoral tunnel as well as Femoral Tunnel Placements. Likewise, Tibial Tunnel Angle in AP & Lateral View as well as Tibial tunnel placement were also significantly different.

CONCLUSION

It is concluded that tunnels follow much different trajectories in the bones in two techniques and trying to apply "Centre of Tibial footprint to Centre of Femoral footprint" philosophy of Transportal technique may be imprudent for Transtibial Technique. An "Off-centre to Off-centre but contained within Footprints" may afford a more predictable and reliable capture of anatomical foot prints without any adverse effect on outcomes.

The Femoral Footprint Position of the Anterior Cruciate Ligament Might Be a Predisposing Factor to a Noncontact Anterior Cruciate Ligament Rupture

BACKGROUND

Although the femoral tunnel position is crucial to anatomic single-bundle anterior cruciate ligament (ACL) reconstruction, the recommendations for the ideal femoral footprint position are mostly based on cadaveric studies with small sample sizes, elderly patients with unknown ACL status, and 2-dimensional techniques. Furthermore, a potential difference in the femoral ACL footprint position and ACL orientation between ACL-ruptured and ACL-intact knees has not been reported in the literature.

HYPOTHESIS

The femoral ACL footprint position and ACL orientation vary significantly between ACL-ruptured and matched control ACL-intact knees.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Magnetic resonance images of the knees of 90 patients with an ACL rupture and 90 matched control participants who had a noncontact knee injury without an ACL rupture were used to create 3-dimensional models of the femur and tibia. The ACL footprints were outlined on each model, and their positions (normalized to the lateral condyle width) as well as ACL orientations were measured with an anatomic coordinate system.

RESULTS

The femoral ACL footprint in patients with an ACL rupture was located at 36.6% posterior and 11.2% distal to the flexion-extension axis (FEA). The ACL orientation was 46.9° in the sagittal plane, 70.3° in the coronal plane, and 20.8° in the transverse plane. The ACL-ruptured group demonstrated a femoral ACL footprint position that was 11.0% more posterior and 7.7% more proximal than that of the control group (all P < .01). The same patients also exhibited 5.7° lower sagittal elevation, 3.1° higher coronal plane elevation, and 7.9° lower transverse plane deviation (all P < .01). The optimal cutoff value of the femoral ACL footprint position to prevent an ACL rupture was at 30% posterior and 12% distal to the FEA.

CONCLUSION

The ACL femoral footprint position might be a predisposing factor to an ACL rupture. Patients with a >30% posterior and <12% distal position of the femoral ACL footprint from the FEA might have a 51.2-times increased risk of an ACL rupture.

Effects of Anteromedial Portal versus Transtibial ACL Tunnel Preparation on Contact Characteristics of the Graft and the Tibial Tunnel Aperture

Background

The purpose of this study was to compare the tibial tunnel aperture contact characteristics simulating an anteromedial and transtibial anterior cruciate ligament (ACL) tunnel preparation.

Methods

Seven matched pairs of cadaveric knees were tested. From each knee, a 10-mm quadriceps ACL graft was prepared. The native ACL was arthroscopically removed and tibial tunnels were drilled. In one knee, a transtibial technique was performed with femoral tunnel drilling approached through the tibial tunnel. For the anteromedial technique on the contralateral knee, the posterior tibial tunnel was chamfered with a rasp. The knees were then disarticulated and tibial tunnel aperture geometry was measured. A pressure sensor was placed between the graft and the posterior aspect of the tibial tunnel and the graft was secured with an interference screw. Contact force, contact area, contact pressure, peak contact pressure, hysteresis and stiffness were measured at cyclic loads of 50 N, 100 N, 150 N, and 200 N.

Results

Tibial tunnel aperture area, diameter and deviation from a circle were significantly larger with the transtibial technique (p < 0.05). There was no significant difference in hysteresis, stiffness, contact area, contact force and mean contact pressure. The peak contact pressure between the ACL graft and the tibial tunnel was significantly higher with the anteromedial technique for 100 N (p = 0.04), 150 N (p = 0.01), and 200 N (p = 0.002) cyclic loading.

Conclusions

Increased peak contact pressure on the graft at the tibial aperture with the anteromedial technique may increase the stress on the graft and possibly lead to failure following ACL reconstruction.

Transportal central femoral tunnel placement has a significantly higher revision rate than transtibial AM femoral tunnel placement in hamstring ACL reconstruction

PURPOSE

It is proposed that central femoral ACL graft placement better controls rotational stability. This study evaluates the consequence of changing the femoral tunnel position from the AM position drilled transtibially to the central position drilled transportally. The difference in ACL graft failure is reported.

METHODS

This prospective consecutive patient single surgeon study compares the revision rates of 1016 transtibial hamstring ACL reconstructions followed for 6-15 years with 464 transportal hamstring ACL reconstructions followed for 2-6 years. Sex, age, graft size, time to surgery, meniscal repair and meniscectomy data were evaluated as contributing factors for ACL graft failure to enable a multivariate analysis. To adjust for the variable follow-up a multivariate hazard ratio, failure per 100 graft years and Kaplan-Meier survivorship was determined.

RESULTS

With transtibial ACLR 52/1016 failed (5.1%). With transportal ACLR 32/464 failed (6.9%). Significant differences between transportal and transtibial ACLR were seen for graft diameter, time to surgery, medial meniscal repair rates and meniscal tissue remaining after meniscectomy. Adjusting for these the multivariate hazard ratio was 2.3 times higher in the transportal group (p = 0.001). Central tunnel placement resulted in a significantly 3.5 times higher revision rate compared to an anteromedial tunnel placement per 100 graft years (p = 0.001). Five year survival was 980/1016 (96.5%) for transtibial versus 119/131 (90.5%) for transportal. Transportal ACLR also showed a significantly higher earlier failure rate with 20/32 (61%) of the transportal failing in the first year compared with 14/52 (27%) for transtibial. (p = 0.001.) CONCLUSION: Transportal central femoral tunnel ACLR has a higher failure rate and earlier failure than transtibial AM femoral tunnel ACLR.

LEVEL OF EVIDENCE

Level II-prospective comparative study.

New Trends in Anterior Cruciate Ligament Reconstruction: A Systematic Review of National Surveys of the Last 5 Years

The purpose of this study was to analyze national surveys of orthopaedic surgeons on anterior cruciate ligament (ACL) reconstruction to determine their preferences related to the preferred graft, femoral tunnel positioning, fixation and tensioning methods, antibiotic and anti-thromboembolic prophylaxis, and use of tourniquet and drains. A systematic search of PubMed, Web of Science, and Cochrane Library was performed. Inclusion criteria were surveys of ACL reconstruction trends and preferences published in the past 5 years (2011–2016), involving members of national societies of orthopaedics. Information regarding survey modalities, population surveyed, graft choice both in the general or in the athletic population, surgical technique, fixation, use of antibiotic, tourniquet, drains, and anti-thromboembolic prophylaxis was extracted. Eight national surveys were included from Europe (three), North or Latin America (three), and Asia (two). Overall, 7,420 questionnaires were sent, and 1,495 participants completed the survey (response rate ranging from 16 to 76.6%). All surveys reported the hamstring tendon (HT) autograft as the preferred graft, ranging from 45 to 89% of the surveyed population, followed by bone-patellar tendon-bone (BPTB) graft (2–41%) and allograft (2–17%). Only two surveys focusing on graft choice in athletic population underlined how in high-demand sportive population the graft choices changes in favor of BPTB. Single-bundle reconstruction was the preferred surgical technique in the four surveys that investigated this issue. Five surveys were in favor of anteromedial (AM) portal and two in favor of trans-tibial technique. Suspension devices for femoral fixation were the preferred choice in all but one survey, while interference screws were the preferred method for tibial fixation. The two surveys that investigated graft tensioning were in favor of manual tensioning. The use of tourniquet, antibiotics, drains, and anti-thromboembolic prophylaxis were vaguely reported. A trend toward the preference of HT autograft was registered in all the surveys; however, sport participation has been highlighted as an important variable for increased use of BPTB. Single-bundle reconstruction with AM portal technique and suspension femoral fixation and screws fixation for the tibia seem the preferred solution. Other variables such as tensioning, antibiotic, anti-thromboembolic prophylaxis, tourniquet use, and drains were investigated scarcely among the surveys; therefore, no clear trends could be delineated. This is a Level V, systematic review of expert opinion study.

[Anatomical study of anterior cruciate ligament and its effect on reconstruction technique]

Objective

To summarize the current research progress of anterior cruciate ligament (ACL) anatomy, and discuss its effect on the reconstruction technique.

Methods

The literature concerning ACL anatomy and reconstruction at home and abroad was extensively reviewed and summarized.

Results

The anatomy and morphology of ACL has gained new recognition in recent years, and the "Ribbon-like" ACL has gradually been paid attention to by researchers. In present researches, it seems the "Ribbon-like" anatomy theory has advantages in theory when compared with the previous anatomy theory. It is more in line with the anatomy and isometric reconstruction.

Conclusion

The understanding of ACL anatomy guided the development of ACL reconstruction. The "Ribbon-like" ACL anatomy theory is the different understanding of the anatomy theory, which remains controversy. The "Ribbon-like" reconstruction maybe has more advantages in theory, but further study is needed.

Transtibial Versus Anteromedial Portal ACL Reconstruction: Is a Hybrid Approach the Best?

BACKGROUND

Improved biomechanical and clinical outcomes are seen when the femoral tunnels of the anterior cruciate ligament (ACL) are placed in the center of the femoral insertion. The transtibial (TT) technique has been shown to be less capable of this than an anteromedial (AM) portal approach but is more familiar to surgeons and less technically challenging. A hybrid transtibial (HTT) technique using medial portal guidance of a transtibial guide wire without knee hyperflexion may offer anatomic tunnel placement while maintaining the relative ease of a TT technique.

PURPOSE

To evaluate the anatomic and biomechanical performance of the HTT technique compared with TT and AM approaches.

STUDY DESIGN

Controlled laboratory study.

METHODS

Thirty-six paired, fresh-frozen human knees were used. Twenty-four knees (12 pairs) underwent all 3 techniques (TT, AM, HTT) for femoral tunnel placement, with direct measurement of femoral insertional overlap and femoral tunnel length. The remaining 12 knees (6 pairs) underwent completed reconstructions to evaluate graft anisometry and tunnel orientation, with each technique performed in 4 specimens and tested using motion sensors with a quad-load induced model. Graft length changes and graft/femoral tunnel angle were measured at varying degrees of flexion.

RESULTS

Percentage overlap of the femoral insertion averaged 37.0% ± 28.6% for TT, 93.9% ± 5.6% for HTT, and 79.7% ± 7.7% for AM, with HTT significantly greater than both TT (P = .007) and AM (P = .001) approaches. Graft length change during knee flexion (anisometry) was 30.1% for HTT, 12.8% for AM, and 8.5% for TT. When compared with the TT approach, HTT constructs exhibited comparable graft-femoral tunnel angulation (TT, 150° ± 3° vs HTT, 142° ± 2.3°; P < .001) and length (TT, 42.6 ± 2.8 mm vs HTT, 38.5 ± 2.0 mm; P = .12), while AM portal tunnels were significantly shorter (31.6 ± 1.6 mm; P = .001) and more angulated (121° ± 6.5°; P < .001).

CONCLUSION

The HTT technique avoids hyperflexion and maintains femoral tunnel orientation and length, similar to the TT technique, but simultaneously achieves anatomic graft positioning.

CLINICAL RELEVANCE

The HTT technique offers an anatomic alternative to an AM portal approach while maintaining the technical advantages of a traditional TT reconstruction.

Current use of navigation system in ACL surgery: a historical review

PURPOSE

The present review aims to analyse the available literature regarding the use of navigation systems in ACL reconstructive surgery underling the evolution during the years.

METHODS

A research of indexed scientific papers was performed on PubMed and Cochrane Library database. The research was performed in December 2015 with no publication year restriction. Only English-written papers and related to the terms ACL, NAVIGATION, CAOS and CAS were considered. Two reviewers independently selected only those manuscripts that presented at least the application of navigation system for ACL reconstructive surgery.

RESULTS

One hundred and forty-six of 394 articles were finally selected. In this analysis, it was possible to review the main uses of navigation system in ACL surgery including tunnel positioning for primary and revision surgery and kinematic assessment of knee laxity before and after different surgical procedures. In the early years, until 2006, navigation system was mainly used to improve tunnel positioning, but since the last decade, this tool has been principally used for kinematics evaluation. Increased accuracy of tunnel placement was observed using navigation surgery, especially, regarding femoral, 42 of 146 articles used navigation to guide tunnel positioning. During the following years, 82 of 146 articles have used navigation system to evaluate intraoperative knee kinematic. In particular, the importance of controlling rotatory laxity to achieve better surgical outcomes has been underlined.

CONLUSIONS

Several applications have been described and despite the contribution of navigation systems, its potential uses and theoretical advantages, there are still controversies about its clinical benefit. The present papers summarize the most relevant studies that have used navigation system in ACL reconstruction. In particular, the analysis identified four main applications of the navigation systems during ACL reconstructive surgery have been identified: (1) technical assistance for tunnel placement; (2) improvement in knowledge of the kinematic behaviour of ACL and other structures; (3) comparison of effectiveness of different surgical techniques in controlling laxities; (4) navigation system performance to improve the outcomes of ACL reconstruction and cost-effectiveness.

LEVEL OF EVIDENCE

IV.

The anatomy of the anterior cruciate ligament and its relevance to the technique of reconstruction

Anterior cruciate ligament (ACL) reconstruction is commonly performed and has been for many years. Despite this, the technical details related to ACL anatomy, such as tunnel placement, are still a topic for debate. In this paper, we introduce the flat ribbon concept of the anatomy of the ACL, and its relevance to clinical practice.

Cite this article: Bone Joint J 2016;98-B:1020–6.

An in Vivo 3D Computed Tomographic Analysis of Femoral Tunnel Geometry and Aperture Morphology Between Rigid and Flexible Systems in Double-Bundle Anterior Cruciate Ligament Reconstruction Using the Transportal Technique

PURPOSE

The aim of this study was to compare femoral tunnel length, femoral graft-bending angle, posterior wall breakage, and femoral aperture morphologic characteristics between rigid and flexible systems after double-bundle (DB) anterior cruciate ligament (ACL) reconstruction using the transportal (TP) technique.

METHODS

We evaluated 3-dimensional computed tomography (3D-CT) results for 54 patients who underwent DB ACL reconstruction using the TP technique with either a flexible system (n = 27) or a rigid system (n = 27). The femoral tunnel length, femoral graft-bending angle, posterior wall breakage, femoral tunnel aperture height to width (H:W) ratio, aperture axis angle, and femoral tunnel position were assessed using OsiriX Imaging Software and Geomagic Qualify 2012 (Geomagic, Cary, NC).

RESULTS

The mean anteromedial (AM) femoral tunnel length of the flexible group was significantly longer than that of the rigid group (P = .009). The mean femoral graft-bending angles in the flexible group were significantly less acute than those in the rigid group (AM, P < .001; posterolateral [PL], P = .003]. Posterior wall breakage was observed in both groups (P = 1.00). The mean H:W ratios in the rigid group were significantly larger (more elliptical) than those of the flexible group (AM, P < .001; PL, P = .006). The mean aperture axis angle of the PL femoral tunnel in the rigid group was more parallel to the femoral shaft axis than that in the flexible group (P < .001). There were no significant differences in femoral tunnel position between the 2 groups.

CONCLUSIONS

The AM femoral tunnel length and the AM/PL femoral graft-bending angle of the flexible system were significantly longer and less acute than those of the rigid system. However, the aperture morphologic characteristics of the AM/PL femoral tunnel and the aperture axis angle of the PL femoral tunnel in the rigid system were significantly more elliptical and closer to parallel to the femoral shaft axis than those of the flexible system.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Clinical Outcomes After Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction: Comparison of Extreme Knee Hyperextension and Normal to Mild Knee Hyperextension

PURPOSE

The aim of this study was to compare postoperative outcomes after anatomic double-bundle anterior cruciate ligament reconstruction (ACLR) in extreme knee hyperextension versus normal to mild knee hyperextension.

METHODS

For 100 patients who underwent anatomic double-bundle ACLR using semitendinosus tendon, we evaluated the side-to-side difference (SSD) in anterior tibial translation (measured on stress radiographs) and rotational stability (assessed by the pivot-shift test) 2 years after surgery. Loss of extension (LOE) was evaluated on lateral radiographs of both knees in full extension, and graft integrity was assessed during second-look arthroscopy 1 to 2 years after surgery. In accordance with the Beighton and Honan criteria, patients with an extension angle less than or equal to 10° in the contralateral uninjured knee composed the group with 10° or less hyperextension (N group), and those with an extension angle of greater than 10° composed the group with more than 10° hyperextension (H group). Postoperative results were compared between these groups.

RESULTS

Mean extension angles in the N and H groups were 5.8° ± 2.9° and 14.7° ± 3.0°, respectively. The mean SSD in anterior translation was 2.2 ± 2.9 mm for the N group and 2.8 ± 2.9 mm for the H group, with no significant difference. The positive ratios on the pivot-shift test were not significantly different between the groups. Mean LOE in the N and H groups was -0.7° ± 3.7° and 1.3° ± 3.3°, respectively, with a significant difference (P = .007). During second-look arthroscopy, 6 of 58 knees in the N group and 13 of 42 knees in the H group had superficial graft laceration of the anteromedial bundle graft, with a significant difference (P = .01) seen between groups.

CONCLUSIONS

Anatomic double-bundle ACLR for extreme knee hyperextension may attain the same postoperative anterior and rotational stability as seen in knees with normal to mild hyperextension. However, it increased superficial graft laceration.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Using an Outside-in Technique: Two- to Six-Year Clinical and Radiological Follow-up

PURPOSE

We evaluated the clinical and radiological outcomes of double-bundle anterior cruciate ligament (ACL) reconstruction using an outside-in technique with a follow-up of two- to six-years, especially in terms of the sports activity level and radiological degeneration.

MATERIALS AND METHODS

Sixty-seven patients who were available for a minimum two-year follow-up after double-bundle ACL reconstruction using an outside-in technique were retrospectively evaluated. The mean follow-up period was 43.7 months. The knee function and stability were evaluated before the operation, one year after the operation (short-term follow-up), and more than two years after the operation (last follow-up).

RESULTS

Regarding the knee function, the Lysholm score, International Knee Documentation Committee (IKDC) evaluation, and hop test showed significant improvement. Regarding the stability, the Lachman test, pivot shift test, KT-2000 arthrometer data, and anterior drawer radiographs using Telos showed significant improvement. Regarding the sports activity level, the patients who returned to pre-injury level activity was 68.7% according to the Tegner activity score and 76.1% according to the Cincinnati sports activity scale score. The incidence of aggravated degeneration or development of greater than IKDC grade A degeneration after surgery was 10.4%.

CONCLUSIONS

Double-bundle ACL reconstruction using an outside-in technique showed favorable clinical and radiological outcomes with respect to the knee function and stability, joint degeneraion, and, especially, return to pre-injury sports activity.

Trans-tibial guide wire placement for femoral tunnel in single bundle anterior cruciate ligament reconstruction

BACKGROUND

Femoral tunnel location is of critical importance for successful outcome of ACL reconstruction. The aim was to study the femoral tunnel created by placing free hand guide wire through tibial tunnel, using the toggle of the guide wire in the tibial tunnel to improve femoral tunnel location.

MATERIALS AND METHODS

30 cases of a single bundle quadrupled hamstring graft anterior cruciate ligament reconstruction by trans-tibial free hand femoral tunnel creation is studied in this prospective study. The side to side play of the guide wire in the tibial tunnel was used to improve the tunnel location on femoral wall. The coronal angle of the femoral tunnel was measured on the anteroposterior radiograph. The femoral tunnel location on the lateral radiograph of the knee was recorded according to Amis method. Lysholm scoring was done preoperative and at each follow up. Assessment of laxity was done by Rolimeter (Aircast(™)) and pivot shift test.

RESULTS

The mean coronal angle of the femoral tunnel in postoperative radiograph was 47°. In lateral radiograph, the femoral tunnel was found to be >60% posterior on Blumensaat line in 67% cases (n = 20) and in the 33% cases (n = 10) it was anterior. The mean Lysholm score improved from 74.6 preoperative to 93.17 postoperative with no objective evidence of laxity.

CONCLUSION

The free hand trans-tibial creation of the femoral tunnel leads to satisfactory coronal obliquity, but it is difficult to recreate anatomic femoral tunnel by this method as the tunnel is consistently anterior in the sagittal plane.

Clinical and three-dimensional computed tomographic comparison between ACL transportal versus ACL transtibial single-bundle reconstructions with hamstrings

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction using a single-bundle transtibial technique can achieve good or excellent results in more than 90% of patients, but anatomical and biomechanical studies have questioned its ability to restore knee function. The purpose of this study was to evaluate clinical and tomographic results (patient satisfaction, knee function, and tunnel location) of patients who underwent transportal or transtibial single-bundle ACL reconstruction.

METHODS

Seventy-one patients with ACL tears were included. Forty-one patients were treated by the single-bundle transportal technique and 30 patients were treated by the single-bundle transtibial technique. Clinical and tomographic data were analyzed in both groups.

RESULTS

After a minimum of 2-year period, the transportal group showed more patients with normal clinical tests than the transtibial group (Lachman [p=0.037], pivot shift [0.00], anterior drawer [0.002]; and arthrometer [0.002] tests). Regarding CT evaluation, transportal and transtibial groups obtained the following femoral central tunnel location (mean [SD]), as percentage: 30 (6.5) and 4.2 (6.4) in high-low axis; and 30.9 (5.9) and 33.2 (4.6) in the deep-shallow axis. Values in the tibial side were, respectively: 38 (6.5) and 46.0 (6.8) in the anterior-posterior axis; and 47.2 (2.5) and 46.9 (2.1) in the medial-lateral axis.

CONCLUSION

CT findings showed that the transportal single-bundle technique positions the ACL tunnel closer to the native ACL footprint in both femur and tibia compared with the transtibial single-bundle technique. Moreover, mild asymptomatic instability and extension deficit were observed more often in the transtibial group.

Modified transtibial versus anteromedial portal technique in anatomic single-bundle anterior cruciate ligament reconstruction: comparison of femoral tunnel position and clinical results

BACKGROUND

Although several studies have compared a conventional transtibial technique with an anteromedial (AM) portal technique for single-bundle (SB) anterior cruciate ligament (ACL) reconstruction, no study to date has investigated whether the modified transtibial technique results in the femoral tunnel being in a similar anatomic position and produces similar clinical outcomes with those of the AM portal technique.

PURPOSE

To compare the clinical outcomes and femoral tunnel position of SB ACL reconstruction using a modified transtibial technique (creating a femoral tunnel with varus and internal rotation of the tibia as well as modification of the tibial tunnel orientation) with those of SB ACL reconstruction using an AM portal technique.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 40 patients (40 knees) who underwent arthroscopic SB ACL reconstruction were included in this study. Patients were randomized using a computer-generated sequence into 2 groups: 20 patients by the modified transtibial technique (group 1) and 20 patients by the AM portal technique (group 2). Clinical evaluations included the 2000 International Knee Documentation Committee (IKDC) subjective knee score, Lysholm knee score, Tegner activity scale, Lachman test, pivot-shift test, 2000 IKDC knee examination, and KT-1000 arthrometer measurement. Three-dimensional computed tomography scans were analyzed according to the quadrant method, and the obliquity of the femoral tunnels in the coronal and sagittal planes and the size of the tunnel orifice were measured.

RESULTS

All clinical parameters improved significantly after SB ACL reconstruction, with no between-group differences. The mean distance of the femoral tunnel center location from the posterior condylar surface (0.8% difference; P = .167) and from the Blumensaat line (2.1% difference; P = .067) was similar in groups 1 and 2. The mean coronal obliquity of the femoral tunnel was significantly lower in group 1 than in group 2 (42.5° ± 6.1° vs 49.3° ± 7.2°, respectively; P = .001), but the mean sagittal obliquity was similar between the 2 groups (41.9° ± 6.1° vs 43.3° ± 5.4°, respectively; P = .303). The mean area of the tunnel orifice was significantly greater in group 1 than in group 2 (11.6 ± 1.4 × 9.2 ± 1.6 mm vs 10.3 ± 1.1 × 9.1 ± 1.4 mm, respectively; P = .013).

CONCLUSION

The modified transtibial technique for SB ACL reconstruction showed good clinical results and anatomic placement of the femoral tunnel, similar with those of the AM portal technique.

Effects of knee flexion angle and loading conditions on the end-to-end distance of the posterior cruciate ligament: a comparison of the roles of the anterolateral and posteromedial bundles

BACKGROUND

It is commonly accepted that the anterolateral (AL) bundle of the posterior cruciate ligament (PCL) is tight in flexion and that the posteromedial (PM) bundle is tight in extension. However, a recent in vivo study showed that both bundles were tight in extension.

PURPOSE

To investigate the effects of knee flexion angle, rotational torque, and anterior/posterior translational force on the end-to-end distance between the femoral and tibial insertion sites of each bundle of the PCL.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Cadaveric knees (10 specimens) were mounted on a robotic system, and the relative positional data between the femur and tibia were acquired during passive flexion/extension, with an applied 5-N·m rotational torque and an applied 89-N translational force. The bony surface and PCL insertion data were acquired with a 3-dimensional scanner after gross dissection and were superimposed onto the positional data. The end-to-end distance between the 2 PCL insertion sites of the femur and tibia was measured.

RESULTS

The end-to-end distance increased from full extension to 90° for both the AL (9.2 ± 1.8 mm; from 30.0 to 39.2 mm) and PM bundles (5.8 ± 2.2 mm; from 32.0 to 37.7 mm). With an internal rotational torque, the end-to-end distance of the PM bundle increased significantly (P < .05) at 0°, 30°, and 60° of knee flexion. Under a posterior translational force at 90° of knee flexion, the length of both bundles increased to their longest measurements (AM bundle: 40.6 ± 4.2 mm; PM bundle: 38.4 ± 3.8 mm).

CONCLUSION

The end-to-end distance of the AL and PM bundles of the PCL increased in flexion, and this pattern was maintained during tests with posterior translational force. The PM bundle was more affected by the rotational torque than was the AL bundle.

CLINICAL RELEVANCE

Both bundles of the PCL may serve a greater functional role in flexion than in extension. The PM bundle might be more important for the control of rotation than the AL bundle. Posterior translation at 90° of knee flexion could be the most stressful condition for both bundles of the PCL, which may have implications for an injury mechanism.

Transtibial versus anteromedial portal anterior cruciate ligament reconstruction using soft-tissue graft and expandable fixation

PURPOSE

To compare clinical outcomes between transtibial drilling and anteromedial portal techniques for anterior cruciate ligament (ACL) reconstruction using soft-tissue grafts secured with expandable fixation.

METHODS

Patients undergoing soft-tissue ACL reconstruction using expandable fixation between 2007 and 2011 were reviewed for inclusion in this study. Revision ACL cases were excluded. All surgeries were performed by 1 of 2 sports medicine fellowship-trained surgeons (T.S.D., K.D.M.). A total of 128 patients (67 comprising transtibial cohort and 61 comprising anteromedial portal cohort) had a minimum of 24 months' follow-up (mean, 27 months) and met the inclusion criteria. The patients were divided into 2 groups based on the method used for creation of the femoral tunnel. At final follow-up, outcomes were assessed with KT-1000 (MEDmetric, San Diego, CA) measurements, as well as International Knee Documentation Committee, Lysholm, and Tegner scores. Data were screened for normality and skew before use of parametric statistics and were transformed if necessary. Data were analyzed by 1-way analysis of variance with post hoc paired comparisons using the Bonferroni approximation.

RESULTS

No differences in demographic characteristics were observed between the 2 groups. There was no significant difference in postoperative KT-1000 measurements between the 2 cohorts (1.571 ± 0.2275 mm in transtibial cohort [n = 35] and 1.246 ± 0.09249 mm in anteromedial cohort [n = 61], P = .1259). A significant improvement in International Knee Documentation Committee scores was observed in the anteromedial cohort, increasing from 41 ± 16 to 89 ± 7.4 (mean ± SD) (P < .0001). Similar changes were observed for the Lysholm score. There was no significant difference between cohorts for any postoperative scores measured (P > .2).

CONCLUSIONS

Our data show comparable KT-1000 measurements for both anteromedial and transtibial femoral drilling techniques when using a soft-tissue graft with expandable fixation.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Anatomic ACL reconstruction produces greater graft length change during knee range-of-motion than transtibial technique

PURPOSE

Because distance between the knee ACL femoral and tibial footprint centrums changes during knee range-of-motion, surgeons must understand the effect of ACL socket position on graft length, in order to avoid graft rupture which may occur when tensioning and fixation is performed at the incorrect knee flexion angle. The purpose of this study is to evaluate change in intra-articular length of a reconstructed ACL during knee range-of-motion comparing anatomic versus transtibial techniques.

METHODS

After power analysis, seven matched pair cadaveric knees were tested. The ACL was debrided, and femoral and tibial footprint centrums for anatomic versus transtibial techniques were identified and marked. Asuture anchor was placed at the femoral centrum and a custom, cannulated suture-centring device at the tibial centrum, and excursion of the suture, representing length change of an ACL graft during knee range-of-motion, was measured in millimeters and recorded using a digital transducer.

RESULTS

Mean increase in length as the knee was ranged 120°–0° (full extension) was 4.5 mm (±2.0 mm) for transtibial versus 6.7 mm (±0.9 mm) for anatomic ACL technique. A significant difference in length change occurs during knee range-of-motion both within groups and between the two groups.

CONCLUSIONS

Change in length of the ACL intra-articular distance during knee range-of-motion is greater for anatomic socket position compared to transtibial position. Surgeons performing anatomic single-bundle ACL reconstruction may tension and fix grafts with the knee in full extension to minimize risk of graft stretch or rupture or knee capture during full extension. This technique may also result in knee anterior–posterior laxity in knee flexion.

Applications of computer navigation in sports medicine knee surgery: an evidence-based review

Computer-assisted surgery (CAS) has been investigated in a number of sports medicine procedures in the knee. Current barriers to its widespread introduction include increased costs, duration, and invasiveness of surgery. Randomized trials on the use of CAS in anterior cruciate ligament reconstruction have failed to demonstrate a clinical benefit. Data on CAS use in high tibial osteotomy are more promising; however, long-term studies are lacking. CAS has a number of research applications in knee ligament surgery, and studies continue to explore its use in the treatment of osteochondral lesions. This article reviews the applications of CAS in sports medicine knee surgery and summarizes current literature on clinical outcomes.

[Evaluation of intraoperative anterior cruciate ligament laxity using a navigation system in the anatomical single bundle reconstruction]

PURPOSE

The anatomical anterior cruciate ligament (ACL) reconstruction attempts to, by reproducing the natural orientation of its fibres, achieve a better rotational stability of the knee. The aim of this paper is to quantify the anteroposterior and rotational laxity of the knee before and after an anatomic ligamentoplasty using the Orthopilot(®) navigation system as a supporting tool. MATHERIAL AND METHOD: We describe the distinctive steps of Orthopilot(®) navigation as well as conducting a retrospective cross-sectional study on a cohort of 20 patients operated in our hospital for chronic primary ACL rupture from january 2010 to may 2011. The precise location of the tunnels was defined with the help of the navigator and the intra-articular landmarks and stability tests were performed in both the sagittal and axial planes.

RESULTS

In our technique for anatomical ACL reconstruction placed the tibial tunnel at a mean distance of 16.8±4.92 mm from the posterior cruciate ligament in a position that represented 44.1%±4.35 of the total width of the tibial plateau. The average distance from the centre of the femoral tunnel to the posterior cortex of the lateral condyle was 7.89±2.78 mm. Intra-operatively and before ACL reconstruction, the mean (±SD) anteroposterior movement, internal rotation and external rotation of the tibia at 30° position were 15.5 mm (±5.11), 19° (±3.62) and 19.65° (±3.26), respectively. After reconstruction these values decreased to 5.6 mm (±1.72°), 12.17° (±3.76) and 16.9° (±4.42), respectively.

CONCLUSIONS

The use of navigation systems supporting the surgery allows the systematic positioning of bone tunnels and standardises the procedures for the desired reconstruction. ACL reconstruction using the technique described, improves the anteroposterior and rotational stability compared to preoperative status, to a stability state that could be considered physiological according to current scientific knowledge.

Anatomic single-bundle anterior cruciate ligament reconstruction in Asian population

BACKGROUND

Non-anatomic tunnel placement, which leads to failure in double-bundle anterior cruciate ligament (ACL), has focused greater attention on single-bundle ACL reconstruction. However, single-bundle ACL with 2- to 4-strand autogenous hamstring tendon graft always showed weak graft strength.

METHODS

To solve this problem, single-bundle ACL with 6-strand autogenous hamstring tendon graft was performed on 32 Asian patients in this study. At 24 months post-operatively, all patients were evaluated with Lysholm knee scores, Tegner activity level and KT-1000 examinations.

RESULTS

The results demonstrated that no patients showed knee extension limitation. Of the 32 patients, there were 26 negative and 6 positive 1° in Lachman test; 31 negative and 1 positive 1° in pivot-shift test. There were four patients with a 5° flexion limitation. The median Lysholm score increased from 45 preoperatively to 92 post-operatively (P < 0.001). The median Tegner sport level score increased from 1 preoperatively to 4 post-operatively (P < 0.001). KT-1000 examination revealed that the median anterior laxity at 25° of flexion was 6.3 mm preoperatively and 1.7 mm post-operatively (P < 0.001).

CONCLUSIONS

The data showed that arthroscopic central anatomic single-bundle ACL reconstruction with 6-strand autogenous hamstring tendon graft is a reliable method to restore stabilization and function of the knee.

Measurement of the end-to-end distances between the femoral and tibial insertion sites of the anterior cruciate ligament during knee flexion and with rotational torque

PURPOSE

The aim of this study was to determine the end-to-end distance changes in anterior cruciate ligament (ACL) fibers during flexion/extension and internal/external rotation of the knee.

METHODS

The positional relation between the femur and tibia of 10 knees was digitized on a robotic system during flexion/extension and with an internal/external rotational torque (5 Nm). The ACL insertion site data, acquired by 3-dimensional scanning, were superimposed on the positional data. The end-to-end distances of 5 representative points on the femoral and tibial insertion sites of the ACL were calculated.

RESULTS

The end-to-end distances of all representative points except the most anterior points were longest at full extension and shortest at 90°. The distances of the anteromedial (AM) and posterolateral (PL) bundles were 37.2 ± 2.1 mm and 27.5 ± 2.8 mm, respectively, at full extension and 34.7 ± 2.4 mm and 20.7 ± 2.3 mm, respectively, at 90°. Only 4 knees had an isometric point, which was 1 of the 3 anterior points. Under an internal torque, both bundles became longer with statistical meaning at all flexion angles (P = .005). The end-to-end distances of all points became longest with internal torque at full extension and shortest with an external torque at 90°.

CONCLUSIONS

Only 4 of 10 specimens had an isometric point at a variable anterior point. The end-to-end distances of the AM and PL bundles were longer in extension and shorter in flexion.

CLINICAL RELEVANCE

The nonisometric tendency of the ACL and the end-to-end distance change during knee flexion/extension and internal/external rotation should be considered during ACL reconstruction to avoid overconstraint of the graft.

Relation between anterior cruciate ligament graft obliquity and knee laxity in elite athletes at the National Football League combine

PURPOSE

The purposes of this study were to determine the incidence of vertical anterior cruciate ligament (ACL) reconstructions in elite athletes and to determine whether graft obliquity correlates with knee stability in this population.

METHODS

One hundred thirty-seven knees in 125 athletes at the 2005-2009 National Football League Combine were identified as having had previous ACL reconstructions. The graft type, fixation, and physical examination findings were recorded for each athlete. Graft obliquity was measured by previously described methods based on plain radiography and magnetic resonance imaging (MRI). Radiographic measurements included tibial tunnel and femoral tunnel locations, as well as a sum of these tunnel positions on the lateral radiograph (sum score). MRI measurements included sagittal and coronal ACL angles and the ACL-Blumensaat line angle. The relation of graft obliquity to physical examination findings was assessed.

RESULTS

Sixty-four percent of knees had vertical grafts based on radiography and 35% based on MRI criteria. The average tibial tunnel location on radiography was 33% from the anterior tibial plateau in the oblique group compared with 42% in the vertical group (P < .0001). Knees with a sum score of 66 or less, tibial tunnel 37% or less from the anterior tibial plateau, and sagittal obliquity of 60° or less were less likely to have increased translation on the Lachman examination than knees with a sum score greater than 66, tibial tunnel greater than 37% from the anterior tibial plateau, and sagittal obliquity greater than 60° (P < .05).

CONCLUSIONS

There was a wide range of ACL graft obliquity in the examined cohort of elite athletes who continued to perform at high levels. Less oblique (more vertical) grafts were associated with greater anterior tibial translation on Lachman testing. ACL graft obliquity, which is particularly sensitive to tibial tunnel placement, can influence knee stability.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Normal sagittal of the anterior cruciate ligament can be reproduced using accessory anteromedial portal technique: a magnetic resonance imaging study

INTRODUCTION

Over time, the need for anatomic anterior cruciate ligament (ACL) to restore normal kinematics and postoperative function of the knee has been accepted. The purpose of this study was to compare the sagittal alignment of reconstructed ACL, which is performed between transtibial (TT) technique and accessory anteromedial (AAM) portal technique and between the reconstructed and the normal side in the same patient. In addition, we used the head of a metallic femoral interference screw as a reference to measure the femoral tunnel position.

PATIENTS AND METHODS

This was a retrospective study with 15 patients in each group: accessory anteromedial portal technique (n = 15), TT technique (n = 15) and contralateral normal side of each technique group (15 knees per technique). Magnetic resonance images of the ACL sagittal angle and radiographs of the coronal screw angle were used for comparing the two groups. The paired t test was used to compare operated and contralateral normal knee and independent t test was used to compare the TT and the AAM groups.

RESULTS

The sagittal angle of ACL of AAM technique (51.6 ± 3.3°) was not different from the normal side (50.8 ± 2.1°) (P = 0.270), however that of the TT technique (59.9 ± 5.7°) was significantly different from the normal side (50.9 ± 2.4°) (P < 0.001). The sagittal angle of AAM technique was significantly lower than that of the TT technique (P < 0.001). The coronal angle of the screw to axis of the femur in AAM technique (51.7 ± 3.8°) was more horizontal than that of the TT technique (24.4 ± 8.9°) (P < 0.001). The center of the screw head of the AAM technique was 30.7 ± 3.1 % of the Blumensaat line and 39.2 ± 5.2 % of the condylar height.

CONCLUSION

The anatomic sagittal angle of ACL can be achieved using the AAM technique compared with the TT technique. In addition, the angle of the screw in coronal plane was more horizontal using the AAM technique than with use of the TT technique.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Anteromedial versus central single-bundle graft position: which anatomic graft position to choose?

PURPOSE

To compare the time-zero stability of an anatomic anteromedial (AM) single-bundle ACL reconstruction to an anatomic central (CTR) single-bundle ACL reconstruction.

METHODS

Twelve (6 paired) hip to knee cadaveric specimens were studied. Using custom ACL computer navigation software, a Lachman test and a previously validated, navigated mechanized pivot shift test were performed on 4 separate experimental groups in each specimen: (1) intact ACL, (2) ACL deficient with total medial and lateral meniscectomy, (3) following anatomic AM single-bundle ACL reconstruction, and (4) after anatomic CTR single-bundle ACL reconstruction. Maximum anterior tibial translation in each group was measured.

RESULTS

Lachman: No significant difference was observed between the AM and CTR reconstructions (n.s.) or between reconstruction and the intact ACL (3.4 ± 1.7 mm) (n.s.). Pivot Shift: Both the AM and CTR ACL reconstructions significantly reduced anterior translation relative to the ACL/menisci-deficient condition (lateral compartment: 8.9 ± 3.8 mm and 6.75 ± 4.6 mm vs. 17.25 ± 3.5 mm, respectively; P < 0.001 and medial compartment: -3.0 ± 5.3 mm vs. -3.7 ± 5.7 mm vs. 6.2 ± 6.7 mm, P < 0.05). There was also a significant difference between the AM (P < 0.001) and CTR (P < 0.05) ACL reconstructions and the intact ACL (2.8 ± 4.4 mm) for lateral compartment translation. Further, no difference was found between lateral or medial compartment translations in the AM versus CTR reconstructions (n.s.).

CONCLUSIONS

It has been shown that there was no difference in the time-zero biomechanical stability between an anatomic anteromedial and anatomic central single-bundle ACL reconstruction. Given the current debate on the best anatomic ACL reconstruction technique, anatomic socket position in either the anteromedial or central locations provides similar time-zero biomechanics.

Variations in the three-dimensional location and orientation of the ACL in healthy subjects relative to patients after transtibial ACL reconstruction

Recent reports have indicated that anatomical placement of the anterior cruciate ligament (ACL) graft is an important factor for restoration of joint function following ACL reconstruction. The objective of this study was to address a need for a better understanding of anatomical variations in ACL position and orientation within the joint. Specifically, variations in the ACL anatomy were assessed by testing for side-to-side ACL footprint location symmetry in a healthy population relative to the operative and contralateral knee in a patient population after traditional transtibial single-bundle ACL reconstruction. MRI and three-dimensional modeling techniques were used to determine the in vivo tibiofemoral ACL footprint centers and the resulting ACL orientations in both knees of 30 healthy subjects and 30 subjects after transtibial ACL reconstruction. While there were substantial inter-subject variations in ACL anatomy, the side-to-side RMS differences in the ACL footprint center were 1.20 and 1.34 mm for the femur and tibia, respectively, for the healthy subjects and no clinically meaningful intra-subject differences were measured. However, there were large intra-subject side-to-side differences after transtibial ACL reconstruction, with ACL grafts placed 5.63 and 7.64 mm from the center of the contralateral femoral and tibial ACL footprint centers, respectively. Grafts were placed more medial, anterior, and superior on the femur and more posterior on the tibia; producing grafts that were more vertical in the sagittal and coronal planes. Given the large variation among subjects, these findings advocate the use of the contralateral ACL morphology for retrospectively evaluating patient-specific anatomic graft placement.

Measuring the anterior cruciate ligament's footprints by three-dimensional magnetic resonance imaging

PURPOSE

The purpose of this study was to compare 3D MR imaging and open cadaveric measurements of the ACL's footprints to see whether 3D MR imaging measurements are accurate enough to be used for preoperative templating in anatomic ACL reconstruction.

METHODS

Eight formalin-injected cadaveric knees were scanned by rapid acquisition isotropic 3D MR imaging. The femoral and tibial footprints were measured on MR imaging and compared with cadaveric dissection. Bland-Altman plots were used to assess the level of agreement.

RESULTS

The AM and PL bundles were clearly appreciated in each specimen by 3D MR imaging and cadaveric dissection. The average paired difference in the femoral and tibial footprint measurements was 2, 1, 2, and 2 mm for the femoral footprint length, femoral footprint width, tibial footprint length, and tibial footprint width, respectively. The individual paired measurements were all within the mean difference ± two standard deviations of the difference in the Bland-Altman plot showing strong agreement.

CONCLUSION

Measuring the ACL's footprint by 3D MR imaging or open cadaveric dissection has strong agreement and can be used interchangeably. 3D MR imaging has the potential to allow surgeons to: (1) tailor ACL reconstruction technique or graft choice based on ACL footprint size, (2) plan for selective bundle ACL reconstruction for partial tears, and (3) preoperatively template tunnel position according to the patient's individual anatomy.

Does computer navigation system really improve early clinical outcomes after anterior cruciate ligament reconstruction? A meta-analysis and systematic review of randomized controlled trials

Inaccurate tunnel placement is an important cause of failure in conventional anterior cruciate ligament (ACL) reconstruction. Controversy currently exists over the usefulness of computer-assisted navigation systems in addressing this problem. Five randomized or quasi-randomized, controlled trials comparing computer-navigated versus conventional technique in ACL reconstructions until December 1, 2009 were identified through a systematical database search. The clinical outcomes of the trials were analyzed by Lachman test, pivot-shift test, International Knee Documentation Committee knee score, Lysholm score, and Tegner score. Mean difference or risk ratio with 95% confidence interval was calculated using a fixed-effects or random-effects model. Heterogeneity across the studies was also assessed. We found that the use of computer-assisted navigation systems led to additional operative time (8-17min). No significant differences between computer-navigated and conventional groups were found in terms of knee stability and functional assessment during short-term follow-up. The role of computer-assisted navigation systems on clinical performance and longevity needs further investigation in large sample, long-term randomized trials.

Correlation between anterior cruciate ligament graft obliquity and tibial rotation during dynamic pivoting activities in patients with anatomic anterior cruciate ligament reconstruction: an in vivo examination

PURPOSE

To investigate the effect of coronal- and sagittal-plane anterior cruciate ligament (ACL) graft obliquity on tibial rotation (TR) range of motion (ROM) during dynamic pivoting activities after ACL reconstruction with bone-patellar tendon-bone (BPTB) autograft.

METHODS

We evaluated 19 ACL-reconstructed patients (mean age, 29 years; age range, 18 to 38 years; mean time interval postoperatively, 19.9 months) and 19 matched control subjects (mean age, 30.6 years; age range, 24 to 37 years) using motion analysis during (1) descending a stairway and pivoting and (2) landing from a jump and pivoting. Magnetic resonance imaging was used to measure the coronal and sagittal ACL graft angle. The dependent variables were TR ROM during pivoting and the side-to-side difference (SSD) in TR ROM between the reconstructed knee and the contralateral intact knee.

RESULTS

TR ROM of the ACL-reconstructed knee was significantly increased compared with both the contralateral intact knee and the healthy control knee (P < .05). A significant positive correlation was observed between TR ROM and coronal ACL graft angle (r = 0.727, P = .0006 for descending and pivoting; r = 0.795, P = .0001 for landing and pivoting) as well as between SSD of TR ROM and coronal ACL graft angle (r = 0.789, P < .0001 for descending and pivoting; r = 0.799, P < .0001 for landing and pivoting). No correlation was found with the sagittal ACL graft angle.

CONCLUSIONS

After ACL reconstruction with a BPTB graft, patients' knees showed higher TR values than their uninjured knees and the knees of uninjured control volunteers during dynamic pivoting activities. The findings of this study show that TR was better restored in ACL-reconstructed patients with a more oblique graft in the coronal plane. A similar relation was not observed for graft orientation in the sagittal plane. Although these data do not imply a cause-and-effect relation between the 2 variables, they may indicate that a more oblique placement of a single BPTB ACL graft in the coronal plane is correlated with better control of TR.

LEVEL OF EVIDENCE

Level IV, case series.

Peri-anterior cruciate ligament reconstruction femur fracture: a biomechanical analysis of the femoral tunnel as a stress riser

PURPOSE

Sixteen case reports of distal femur fractures as post-operative complications after anterior cruciate ligament (ACL) reconstruction have been described in the literature. The femoral tunnel has been suggested as a potential stress riser for fracture formation. Additionally, double bundle ACL reconstructions may compound this risk. This is the first biomechanical study to examine the significance of a stress riser effect of the femoral tunnel(s) after ACL reconstruction. The hypotheses tested in this study are that the femoral tunnel acts as a stress riser for fracture and that this effect increases with the size of the tunnel (8 mm vs. 10 mm) and with the number of tunnels (1 vs. 2).

METHODS

Femoral tunnels simulating single bundle (SB) hamstring graft (8 mm), bone-patellar tendon-bone graft (10 mm), and double bundle (DB) ACL reconstruction (7, 6 mm) were drilled in fourth-generation saw bones. These three experimental groups and a control group consisting of native saw bones without tunnels were loaded to failure.

RESULTS

All fractures occurred through the tunnels in the DB group, whereas fractures did not consistently occur through the tunnels in the SB groups. The mean fracture load was 6,145N ± 471N in the native group, 5,691N ± 198N in the 8 mm SB group, 5,702N ± 282N in the 10 mm SB group, and 4,744N ± 418N in the DB group. The mean fracture load for the DB group was significantly lower when compared to the native, 8 mm SB, and 10 mm SB groups independently (P value = 0.0016, 0.0060, and 0.0038, respectively). The mean fracture loads for neither SB groups were not significantly different from the native group.

CONCLUSIONS

An anatomically placed femoral tunnel in single bundle ACL reconstruction in our experimental model was not a significant stress riser to fracture, whereas the two femoral tunnels in double bundle ACL reconstruction significantly decreased load to failure. The results support the sparsity of reported peri-ACL reconstruction femur fractures in single femoral tunnel techniques. However, the increased fracture risk in double bundle ACL reconstruction may be a cause for concern and impact patient selection.

Effect of tunnel position and graft size in single-bundle anterior cruciate ligament reconstruction: an evaluation of time-zero knee stability

PURPOSE

To determine whether (1) increased graft size with anatomic anterior cruciate ligament reconstruction (ACLR) would confer proportionally increased time-zero biomechanical stability and (2) larger grafts would compensate for the inferior time-zero biomechanical kinematics of nonanatomic, single-bundle ACLR.

METHODS

Ten cadaveric knees were allocated for single-bundle ACLR in an anatomic, center-center or nonanatomic, posterolateral-to-anteromedial footprint position with hamstring autograft. Medial arthrotomy defined the native anterior cruciate ligament (ACL) tibial and femoral footprints. ACLR was performed with a 6-mm semitendinosus graft in 6-mm tunnels and repeated with a 9-mm semitendinosus and gracilis graft in 9-mm tunnels for each knee. Lachman and instrumented pivot-shift examinations assessed knee stability in the ACL-intact, ACL-deficient, and ACLR conditions. Medial and lateral meniscectomies after ACL transection created reproducible pivot shifts. Significance was defined as P < .05.

RESULTS

ACLR in the center-center or posterolateral-to-anteromedial position significantly reduced anterior tibial translation compared with the ACL- and meniscus-deficient conditions (P < .001). Larger graft size, however, did not significantly improve time-zero biomechanical stability compared with a smaller graft in the same position for either reconstruction (P = .41 to .74). A center-center ACLR controlled tibial translation significantly better than a nonanatomic graft position regardless of graft size (P < .001). A smaller graft in the anatomic position controlled tibial translation significantly better than a larger graft in a nonanatomic position (P < .001).

CONCLUSIONS

This study showed that increasing graft size did not improve the time-zero biomechanical stability of the knee after ACLR. Increased graft size did not compensate for the biomechanical instability documented with the nonanatomic tunnel position. Restoration of native footprint anatomy in ACLR is of paramount importance regardless of graft size and source.

CLINICAL RELEVANCE

A larger graft size does not ameliorate the inferior time-zero biomechanics associated with nonanatomic tunnel preparation during single-bundle ACLR.

Comparison of anterior cruciate ligament tunnel position and graft obliquity with transtibial and anteromedial portal femoral tunnel reaming techniques using high-resolution magnetic resonance imaging

PURPOSE

Using 3-dimensional high-resolution magnetic resonance imaging (MRI), we sought to compare femoral and tibial tunnel position and resultant graft obliquity with single-bundle anterior cruciate ligament (ACL) reconstruction using transtibial (TT) or anteromedial (AM) portal femoral tunnel reaming techniques.

METHODS

Thirty patients were prospectively enrolled after primary, autogenous bone-patellar tendon-bone ACL reconstruction by 2 groups of high-volume, fellowship-trained sports medicine surgeons. With the TT technique, an external starting point was used to maximize graft obliquity and femoral footprint capture. By use of high-resolution MRI and imaging analysis software, bilateral 3-dimensional knee models were created, mirrored, and superimposed. Differences between centroids for each femoral and tibial insertion, as well as corresponding ACL/graft obliquity, were evaluated with paired t tests and 2-sided Mann-Whitney nonparametric tests, with P < .05 defined as significant.

RESULTS

No significant differences were observed between groups in position of reconstructed femoral footprints. However, on the tibial side, AM centroids averaged 0.8 ± 1.9 mm anterior to native ACL centroids, whereas the TT group centered 5.23 ± 2.4 mm posterior to native ACL centroids (P < .001). Sagittal obliquity was closely restored with the AM technique (mean, 52.2° v. 53.5° for native ACL) but was significantly more vertical (mean, 66.9°) (P = .0001) for the TT group.

CONCLUSIONS

In this clinical series, AM portal femoral tunnel reaming more accurately restored native ACL anatomy than the TT technique. Although both techniques can capture the native femoral footprint with similar accuracy, the TT technique requires significantly greater posterior placement of the tibial tunnel, resulting in decreased sagittal graft obliquity. When a tibial tunnel is drilled without the need to accommodate subsequent femoral tunnel reaming, more accurate tibial tunnel position and resultant sagittal graft obliquity are achieved.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Tunnel position and graft orientation in failed anterior cruciate ligament reconstruction: a clinical and imaging analysis

PURPOSE

It has been reported that technical error in positioning the graft tunnel is the most common problem in anterior cruciate ligament (ACL) reconstruction. The objective of this study was to quantitatively evaluate femoral and tibial tunnel positions and intra-articular graft orientation of primary ACL reconstruction in patients who had undergone revision ACL reconstruction. We postulated that this patient cohort had a nonanatomically positioned tunnel and graft orientation.

METHODS

Twenty-six patients who had undergone a revision ACL were investigated. Clinical magnetic resonance (MR) images prior to revision were analysed. Three-dimensional models of bones and tunnels on the femur and tibia were created. Intra-articular graft orientation was measured in axial, sagittal and coronal planes. Graft positions were measured on the tibial plateau as a percentage from anterior to posterior and medial to lateral; graft positions on the femur were measured using the quadrant method.

RESULTS

Sagittal elevation angle for failed ACL reconstruction graft (69.6° ± 13.4°) was significantly greater (p < 0.05) than that of the native anteromedial (AM) and posterolateral (PL) bundles of the ACL (AM 56.2° ± 6.1°, PL 55.5° ± 8.1°). In the transverse plane, the deviation angle of the failed graft (37.3° ± 21.0°) was significantly greater than native ACL bundles. The tibial tunnel in this patient cohort was placed posteromedially and medially to the anatomical AM and PL bundles, respectively. The femoral tunnel was placed anteriorly to the anatomical AM and PL bundles.

CONCLUSIONS

This study reveals that both the tibial and femoral tunnel positions and consequently the intra-articular graft orientation in this patient group with failed ACL reconstruction were nonanatomical when compared with native ACL values. The results can be used to improve tunnel placement in ACL reconstruction.

Tunnel position and graft orientation in failed anterior cruciate ligament reconstruction: a clinical and imaging analysis

PURPOSE

It has been reported that technical error in positioning the graft tunnel is the most common problem in anterior cruciate ligament (ACL) reconstruction. The objective of this study was to quantitatively evaluate femoral and tibial tunnel positions and intra-articular graft orientation of primary ACL reconstruction in patients who had undergone revision ACL reconstruction. We postulated that this patient cohort had a nonanatomically positioned tunnel and graft orientation.

METHODS

Twenty-six patients who had undergone a revision ACL were investigated. Clinical magnetic resonance (MR) images prior to revision were analysed. Three-dimensional models of bones and tunnels on the femur and tibia were created. Intra-articular graft orientation was measured in axial, sagittal and coronal planes. Graft positions were measured on the tibial plateau as a percentage from anterior to posterior and medial to lateral; graft positions on the femur were measured using the quadrant method.

RESULTS

Sagittal elevation angle for failed ACL reconstruction graft (69.6° ± 13.4°) was significantly greater (p < 0.05) than that of the native anteromedial (AM) and posterolateral (PL) bundles of the ACL (AM 56.2° ± 6.1°, PL 55.5° ± 8.1°). In the transverse plane, the deviation angle of the failed graft (37.3° ± 21.0°) was significantly greater than native ACL bundles. The tibial tunnel in this patient cohort was placed posteromedially and medially to the anatomical AM and PL bundles, respectively. The femoral tunnel was placed anteriorly to the anatomical AM and PL bundles.

CONCLUSIONS

This study reveals that both the tibial and femoral tunnel positions and consequently the intra-articular graft orientation in this patient group with failed ACL reconstruction were nonanatomical when compared with native ACL values. The results can be used to improve tunnel placement in ACL reconstruction.

Anatomic single- and double-bundle anterior cruciate ligament reconstruction, part 1: Basic science

Anterior cruciate ligament reconstruction is a frequently performed orthopaedic procedure. Although short-term results are generally good, long-term outcomes are less favorable. Thus, there is renewed interest in improving surgical techniques. Recent studies of anterior cruciate ligament anatomy and function have characterized the 2-bundle structure of the native ligament. During non-weightbearing conditions, the anteromedial (AM) and posterolateral (PL) bundles display reciprocal tension patterns. However, during weightbearing, both the AM and PL bundles are maximally elongated at low flexion angles and shorten significantly with increasing knee flexion. Conventional single-bundle reconstruction techniques often result in nonanatomic tunnel placement, with a tibial PL to a femoral "high AM" tunnel position. In vitro studies have demonstrated that these nonanatomic single-bundle reconstructions cannot completely restore normal anterior-posterior or rotatory laxity. Cadaveric studies suggest that anatomic single-bundle and anatomic double-bundle reconstruction may better restore knee stability. Although many cadaver studies suggest that double-bundle reconstruction techniques result in superior stability when compared with single-bundle techniques, others failed to demonstrate a clear benefit of this more complex procedure. Cadaver studies generally do not apply physiologically relevant loads and provide only a "time-zero" assessment that ignores effects of healing and remodeling after anterior cruciate ligament reconstruction. In vivo, dynamic studies offer the most comprehensive assessment of knee function after injury or reconstruction, as they can evaluate dynamic stability during functional joint loading. Studies of knee kinematics during activities such as gait and running suggest that nonanatomic single-bundle anterior cruciate ligament reconstruction fails to restore preinjury knee function under functional loading conditions. Similar studies of more anatomic single- and double-bundle surgical approaches are in progress, and preliminary results suggest that these anatomic techniques may be more effective for restoring preinjury knee function. However, more extensive, well-designed studies of both kinematics and long-term outcomes are warranted to characterize the potential benefits of more anatomic reconstruction techniques for improving long-term outcomes after anterior cruciate ligament reconstruction.

Can anatomic femoral tunnel placement be achieved using a transtibial technique for hamstring anterior cruciate ligament reconstruction?

BACKGROUND

Recent studies have emphasized the importance of anatomic tunnel placement during anterior cruciate ligament (ACL) reconstruction in an effort to restore normal knee kinematics and stability. Secondary to the constraints imposed by a coupled drilling technique, the ability to achieve an anatomic femoral tunnel during transtibial hamstring ACL reconstruction may be limited.

HYPOTHESIS

The size limitations imposed by the small-diameter tibial tunnel used in hamstring ACL reconstruction would preclude the ability to place an anatomic femoral tunnel.

STUDY DESIGN

Descriptive laboratory study.

METHODS

In a descriptive laboratory study, fresh-frozen human cadaveric knees fixed at 90° of flexion were dissected to expose the centers of the native femoral and tibial ACL insertions. The geometry and location of each insertion were evaluated. Using a standardized starting point, tibial tunnels were drilled to the center of the tibial insertion using an 8-mm reamer. Next, a 6-mm over-the-top guide was used to position as close as possible to the anatomic femoral ACL insertion on the lateral wall, and femoral tunnels were drilled with the 8-mm reamer. For each tunnel, the location, geometry, and percentage overlap with the native insertion site were evaluated using a 3-dimensional laser scanner.

RESULTS

The reamed tibial tunnel was central within the insertion site, occupying 40.4% ± 2.0% of the native tibial insertion. Transtibial drilling resulted in femoral tunnels that were superior and posterior compared with the native femoral insertion. Thefemoral tunnel had a mean ± SD overlap of 30.0% ± 12.6% with the femoral insertion, with the center of the tunnel 7.6± 0.5 mm from the center of the native ACL femoral insertion.

CONCLUSION

Based on our data using our specific starting point, during hamstring ACL reconstructions, the constraints imposed by a coupled drilling technique result in nonanatomic femoral tunnels that are superior and posterior to the native femoral insertion.

CLINICAL RELEVANCE

Anatomic femoral tunnel placement during hamstring ACL reconstructions may not be possible using a coupled, transtibial drilling approach.