Varying femoral tunnels between the anatomical footprint and isometric positions: effect on kinematics of the anterior cruciate ligament-reconstructed knee

Evaluation of the semitendinosus tendon graft shift in the bone tunnel: an experimental study

PURPOSE

The purpose of this study was to measure the semitendinosus tendon graft shift at the tunnel aperture with graft bending using a simulated femoral bone tunnel.

METHODS

Eight semitendinosus tendon grafts were used in this study. The median age of the specimen was 53 years (range 46-63). After stripping excess soft tissue, the semitendinosus tendon was doubled over the loop of the EndoButton CL (Smith and Nephew Inc.). The diameter of the graft was measured using a graft-sizing tube (Smith and Nephew Inc.) and verified to be 7.0 mm. A custom-made aluminium fixture, the size was 40.0 mm(3), with 7.0-mm-diameter hole was used as a simulated femoral bone tunnel. The graft was inserted to the tunnel, and EndoButton was positioned to the outside of the tunnel on the fixture. The distal end of the graft was tensioned with 30 N at an angle of 15°, 30°, 45°, 60°, 75° that reproduced the graft bending angle during knee range of motion. The photograph of the tunnel aperture was taken at each graft bending angle using a digital camera, and the graft shift amount in the simulated tunnel was analysed using the computer software (ImageJ).

RESULTS

The amount of the graft shift significantly increased when the graft bending angle was increased (P < 0.05). The biggest shift was observed when the graft bending angle was 75° in all specimens, and the value was 1.10 mm ± 0.12.

CONCLUSION

The present study suggests that even if the femoral tunnel was created in the centre of the ACL insertion site, the graft shifted within the tunnel in the direction of the tension applied to the graft during knee range of motion. Surgeons may have to consider the graft shift within the bone tunnel as well as the tunnel position in the restoration of the native ACL anatomy.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

Level III, diagnostic study.

Anatomic Tunnel Placement in Anterior Cruciate Ligament Reconstruction

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

Transportal femoral drilling creates more horizontal ACL graft orientation compared to transtibial drilling: A 3D CT imaging study

BACKGROUND

The principle of anatomic anterior cruciate ligament (ACL) reconstruction is to create a femoral and tibial tunnel that resembles the insertion of the native ACL. Anatomic reconstruction leads to a more horizontal graft orientation that provides more rotational stability. The aim of this study is to investigate the best method to achieve anatomical reconstruction of femoral insertion of the ACL and thus, a more horizontal orientation of the ACL. We compared tunnel position and orientation between transportal femoral drilling technique and transtibial technique.

METHODS

Thirty-two patients were included. Post-operative CT scans were obtained and femur, tibia and ACL tunnels were reconstructed. The position and orientation of tibial and femoral tunnels were quantified using the quadrant method, and femoral tunnel length, ellipticity and posterior wall breakage were assessed. We also investigated clinical outcome.

RESULTS

Analyses show that transportal drilled femoral tunnels were situated significantly lower than transtibial drilled tunnels (p<0.0001), resulting in a significantly more horizontal oriented ACL in the transportal group in coronal (p<0.0001) and sagittal plane (p=0.01). No differences were observed in depth of femoral tunnel position (p=0.44). Femoral tunnel length was shorter in the transportal group (p=0.01) with a more ellipsoidal femoral aperture (p=0.01). There were no differences between both groups in tibial position. There were no differences in clinical outcome measure between the transportal and transtibial groups.

CONCLUSION

This study indicates that transportal drilling of the femoral tunnel leads to a more horizontal graft orientation of the ACL, without differences in clinical outcome.

Predictive mathematical modeling of knee static laxity after ACL reconstruction: in vivo analysis

Previous studies did not take into consideration such large variety of surgery variables which describe the performed anterior cruciate ligament (ACL) reconstruction and the interaction among them in the definition of postoperative outcome. Seventeen patients who underwent navigated Single Bundle plus Lateral Plasty ACL reconstruction were enrolled in the study. Static laxity was evaluated as the value of anterior/posterior displacement at 30° and at 90° of flexion, internal/external rotation at 30° and 90° of knee flexion, varus/valgus test at 0° and 30° of flexion. The evaluated surgical variables were analyzed through a multivariate analysis defining the following models: AP30estimate, AP90estimate, IE30estimate, IE90estimate, VV0estimate, VV30estimate. Surgical variables has been defined as the angles between the tibial tunnel and the three planes, the lengths of the tunnel and the relationship between native footprints and tunnels. An analogous characterization was performed for the femoral side. Performance and significance of the defined models have been quantified by the correlation ratio (η(2)) and the corresponding p-value (*p < 0.050). The analyzed models resulted to be statistically significant (p < 0.05) for prediction of postoperative static laxity values. The only exception was the AP90estimate model. The η(2) ranged from 0.568 (IE90estimate) to 0.995 (IE30estimate). The orientation of the tibial tunnel resulted to be the most important surgical variable for the performed laxity estimation. Mathematical models for postoperative knee laxity is a useful tool to evaluate the effects of different surgical variables on the postoperative outcome.

Conventional over-the-top-aiming devices with short offset fail to hit the center of the human femoral ACL footprint in medial portal technique, whereas medial-portal-aiming devices with larger offset hit the center reliably

INTRODUCTION

Aim of this study was to investigate the accuracy of a conventional over-the-top-guide (OTG) with a typically short offset to hit the center of the native femoral ACL footprint through the anteromedial portal in comparison to a specific medial-portal-aimer (MPA) with larger offset.

MATERIALS AND METHODS

In 20 matched human cadaveric knees, insertion sites of the ACL were marked in medial arthrotomy. An OTG with an offset of 5.5 mm, respectively, the MPA with 9 mm offset was used in a medial portal approach to locate the center of a single bundle ACL reconstruction tunnel with k-wires. Distances from the footprint center, the OTG drilling and the MPA drilling to the roof of the intercondylar notch and to the deep cartilage margin were determined. After positioning of radiological markers, radiographic analysis was performed according to the quadrant technique as described by Bernard and Hertel.

RESULTS

The distance from ACL origin to the roof of the notch was 10.3 (±2.1) mm, in the OTG group 6.7 (±1.5) mm and in the MPA group 9.6 (±1.9) mm. The distance to the deep cartilage margin was 9.5 (±1.7) mm from ACL origin, 4.8 (±1.3) mm with OTG and 8.7 (±1.4) mm with MPA. There were statistically significant differences between the distances of the footprint center and the OTG group after measuring and also after radiographic analysis (p < 0.0001). Using the MPA, no significant different distances in comparison to the anatomical ACL center were found (p > 0.0001). There was an increased risk for femoral blow (9/10 vs. 0/10) in the OTG group after overdrilling with a 9 mm drill.

CONCLUSION

Short (5.5 mm) offset femoral aiming devices fail to locate the native ACL footprint center in medial portal approach with an increased risk for femoral blowout when overdrilling. The special medial-portal-aiming device with 9 mm offset hit the center reliably.

Transtibial vs anatomical single bundle technique for anterior cruciate ligament reconstruction: A Retrospective Cohort Study

INTRODUCTION

Most of the ACL reconstruction is done with isometric single-bundle technique. Traditionally, surgeons were trained to use the transtibial technique (TT) for drilling the femoral tunnel. Our study compared the early postoperative period functional and clinical outcomes of patients who had ACL reconstruction with TT and patients who had ACL reconstruction with anatomical single-bundle technique (AT).

MATERIAL METHOD

Fifty-five patients who had ACL reconstruction and adequate follow-up between January 2010-December 2013 were included the study. Patients were grouped by their surgery technique. 28 patients included into anatomical single-bundle ACL reconstruction surgery group (group 1) and 27 patients were included into transtibial AC reconstruction group (group 2). Average age of patients in group 1 and group 2 was 28.3 ± 6, and 27.9 ± 6.4, respectively. Lachman and Pivot-shift tests were performed to patients. Laxity was measured by KT-1000 arthrometer test with 15, 20 and 30 pound power. All patients' muscle strength between both extremities were evaluated with Cybex II (Humac) at 60°/sec, 240°/sec frequencies with flexion and extension peak torque. The maximum force values of non-operated knee and the operated knee were compared to each other. Groups were evaluated by using International Knee Documentation Committee (IKDC) knee ligament healing Standard form, IKDC activity scale, modified Lysholm and Cincinnati evaluation forms. Return to work and exercise time of patients were compared. Functional and clinical outcomes of two groups were compared. NCSS 2007 and PASS 2008 Statistical Software programs were used for statistical analysis.

RESULT

There was no statistically significant difference between Lachman and Pivot-shift results (p > 0.01). Positive value of Pivot-shift test and incidence of anterior translation in Lachman test were higher in the patients who had TT. Lysholm activity level of patients who had TT, 33.3% (n = 9) were excellent, 51.9% (n = 14) were good and 14.8% (n = 4) were moderate; patients who had AT, 57.1% (n = 16) were excellent, 39.3% (n = 11) were good and 3.6% (n = 1) was good level. There was no statistically significant difference between Lysholm Activity level of the patients (p < 0.01). Lysholm Activity level of patients who had AT significantly higher than TT. There was no statistically significant difference between Modified Cincinnati activity level of the patients (p < 0.05). Modified Cincinnati activity level of patients who had AT were significantly higher than those had TT. There was no statistically significant difference between two groups with post treatment IKDC activity level (p < 0.01). Intense activity after treatment rate of patient who had AT was significantly higher than those had TT. There was statistically significant difference between Cybex extension-flexion 60 measurement and extension 240 measurement of the patients (p < 0.01). KT-1000 arthrometer test results with AT was better than the TT in antero-posterior translation of the knee kinematics at 20 and 30 pound of forces. Return to exercise time of patients who had TT was significantly higher than those had AT (p < 0.01). There was no statistically significant difference between return to work time of patients (p > 0.05).

CONCLUSION

Single-bundle anatomic ACL reconstruction was better than the TT in term of clinical, functional, and laboratory results. We believe that AT ACL reconstruction will increase in use and traditional method which is TT ACL reconstruction surgery will decrease in the long term. Theoretically, anatomic relocation of the ACL can provide better knee kinematics.

Editorial Commentary: Anatomic Femoral Tunnel Drilling: Does It Really Matter?

An anatomic anteromedial portal and outside-in technique for creating the anterior cruciate ligament femoral tunnel may improve rotational stability but shows no published differences in clinical outcomes.

The effect of feedback from post-operative 3D CT on placement of femoral tunnels in single-bundle anatomic ACL reconstruction

PURPOSE

To evaluate the effect of feedback from post-operative 3D CT in the learning process of placing the femoral graft tunnel anatomically using the anteromedial (AM)-portal technique in single-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

An experienced knee surgeon converting from transtibial to AM-portal technique was offered post-operative feedback on tunnel placement. Three groups of patients were included: transtibial drilling, (AM1) anteromedial drilling without feedback and (AM2) anteromedial drilling with post-operative CT feedback. Intra-articular landmarks were used as the only guidance for tunnel placement. Tunnel position was compared to an ideal anatomical ACL position using the Bernard and Hertel grid and visual feedback was given on tunnel placements. The effect of feedback was measured as the distance from the anatomical centre, and spread of tunnel placements on post-operative CT performed feedback was initiated.

RESULTS

When comparing the femoral tunnel placement to an ideal anatomical centre, there was an improvement in the mean tunnel position after (A) changing from a transtibial to an anatomical technique and a further improvement after (B) initializing the radiological feedback. There was a great variation of femoral tunnel localizations when initially only using intra-articular landmarks as guidance for tunnel placement--this variation, however, converged towards the anatomical centre throughout the feedback period and the AM2 group had a femoral tunnel closer (P = 0.001) to the anatomical centre than the AM1 group.

CONCLUSIONS

Post-operative 3D CT is effective in the learning process of placing femoral tunnels anatomically by giving post-operative feedback on tunnel placement. Bony landmarks and ACL remnants were found unreliable as the only guidance for femoral tunnel placement in the AM-portal technique-therefore, the use of an aid is recommended to reduce unwanted tunnel variations in a learning phase.

LEVEL OF EVIDENCE

Cohort Study, Level III.

Tunnel collision during simultaneous anterior cruciate ligament and posterolateral corner reconstruction

PURPOSE

To verify the safest angle to drill femoral tunnels in simultaneous anterior cruciate ligament (ACL) and posterolateral corner (PLC) reconstructions to minimize the risk of tunnel collision and to examine the relationship between lateral femoral condyle (LFC) width and tunnel collision occurrence.

METHODS

Ten fresh-frozen cadaveric knees were used. In each knee, anatomical single-bundle ACL femoral tunnels were arthroscopically drilled at 120 and 140 degrees of flexion, and tunnels for popliteus tendon (PLT) and fibular collateral ligament (FCL) were drilled at 20° axial/20° coronal angulations and 10° axial/30° coronal angulations. Three-dimensional computed tomography exams of the knees were performed. The presence of tunnel collision was evaluated, and the minimal distance between tunnels and the LFC width was measured.

RESULTS

Risk of tunnel collision was significantly increased if FCL and PLT tunnels were drilled at 10° axial/30° coronal angulation (P < 0.05). Tunnel collision was noted in only one knee when FCL and PLT tunnels were drilled at 20° axial/20° coronal angulations. Knees with smaller LFC width had significantly higher risk for tunnel collision (P < 0.05).

CONCLUSION

Drilling PLT and FCL femoral tunnels at 20° axial/20° coronal angulation is a safe positioning for simultaneous ACL and PLC reconstructions. However, in smaller knees, the risk for tunnel collision could be greater. Surgeons should consider the possibility of tunnel collision when performing simultaneous ACL and PLC anatomical reconstruction, especially in knees with a small LFC width where the risk for tunnel collision could be greater.

Comparison of Knee Kinematics After Single-Bundle Anterior Cruciate Ligament Reconstruction via the Medial Portal Technique With a Central Femoral Tunnel and an Eccentric Femoral Tunnel and After Anatomic Double-Bundle Reconstruction: A Human Cadaveric Study

BACKGROUND

Anatomic femoral tunnel placement in anterior cruciate ligament (ACL) reconstruction is considered to be a key to good primary stability of the knee. There is still no consensus on whether a centrally placed single bundle in the anatomical femoral footprint can compare with anatomic double-bundle (DB) reconstruction.

PURPOSE/HYPOTHESIS

The purpose of this study was to determine knee kinematics after single-bundle ACL reconstruction via the medial portal technique using 2 different femoral tunnel positions and to compare results with those of the anatomic DB technique. The hypotheses were that (1) single-bundle reconstruction using the medial portal technique with a centrally placed femoral tunnel relative to the native footprint (SB-central technique) would more closely restore intact knee kinematics compared with the same reconstruction technique with an eccentric femoral tunnel drilled in the anteromedial bundle footprint (SB-AM technique) and (2) DB reconstruction would result in superior kinematics compared with the SB-central technique.

STUDY DESIGN

Controlled laboratory study.

METHODS

Knee kinematics was examined in 10 fresh-frozen human cadaveric knees using a robotic/universal force-moment sensor system. Kinematics in simulated pivot-shift and 134-N anterior tibial loading tests were determined in different conditions within the same specimen: (1) intact ACL, (2) deficient ACL, (3) SB-AM, (4) SB-central, and (5) DB.

RESULTS

All reconstruction techniques significantly reduced anterior tibial translation (ATT) compared with a deficient ACL at 0°, 15°, 30°, 60°, and 90° in the anterior tibial loading test (P < .01, repeated-measures analysis of variance) and at 0°, 15°, and 30° in the simulated pivot-shift test (P < .001). There were no significant differences in the SB-central group and the DB group compared with the intact ACL. Reconstruction in the SB-AM group resulted in significantly increased ATT compared with the intact ACL in near-to-extension angles in both tests (0°, 15°, and 30°; P < .01). SB-central and DB reconstructions both resulted in significantly reduced ATT, in some tests at ≤30°, compared with SB-AM reconstruction (P < .05). No significant differences between the SB-central and DB groups were found (P > .05).

CONCLUSION

The SB-central technique restored intact knee kinematics more closely than did SB-AM reconstruction at time zero. There were no differences in knee kinematics between the DB and SB-central techniques.

CLINICAL RELEVANCE

Anatomic single-bundle ACL reconstruction provides similar knee kinematics as anatomic double-bundle reconstruction.

Knee stability, athletic performance and sport-specific tasks in non-professional soccer players after ACL reconstruction: comparing trans-tibial and antero-medial portal techniques

BACKGROUND

a wrong position of bone tunnels, in particular on the femur, is one of the most frequent causes of a failed anterior cruciate ligament (ACL) reconstruction. Several studies demonstrated that drilling the femoral tunnel through the antero-medial portal (AMP) allows a more anatomical placement on the lateral femoral condyle and higher knee stability, compared to trans-tibial (TT) technique. The aim of this study was to retrospectively evaluate two groups of soccer players operated on for ACL reconstruction according to either one of these two techniques.

METHODS

two groups of non-professional soccer players operated on for a single bundle ACL reconstruction with hamstrings autograft using either a TT (20 patients) or an AMP (23 patients) technique were retrospectively evaluated with KT-1000 arthrometer, manual pivot shift test, isokinetic test, the incremental treadmill-running test, athletic and sport specific tasks, and knee scores (IKDC, Lysholm and KOOS).

RESULTS

the AMP group showed better results at pivot shift test and KOOS, but lower flexion angles at single leg squat test. There were no differences in all the other considered outcomes.

CONCLUSIONS

the better rotational stability of the knee achieved in AMP group did not lead to significantly better clinical and functional results in our patients.

LEVEL OF EVIDENCE III TREATMENT STUDY

Case-control study.

Clinically relevant anatomy and what anatomic reconstruction means

BACKGROUND

Within the past 20 years, knee ligament injuries have been increasingly reported in the literature to be treated with anatomic reconstructions over soft tissue advancements or sling-type procedures to recreate the native anatomy and restore knee function. Historically, early clinician scientists published on the qualitative anatomy of the knee, which provided a foundation for the initial knee biomechanical studies in the nineteenth and twentieth centuries. Similarly, the work of early sports medicine orthopaedic clinician scientists in the late twentieth century formed the basis for the quantitative anatomic and functional robotic biomechanical studies found currently in the sports medicine orthopaedic literature. The development of an anatomic reconstruction first requires an appreciation of the quantitative anatomy and function of each major stabilizing component of the knee.

PURPOSE

This paper provides an overview of the initial qualitative anatomic studies from which the initial knee ligament surgeries were based and expands to recent detailed quantitative studies of the major knee ligaments and the renewed recent focus on anatomic surgical reconstructions.

CONCLUSIONS

Anatomic repairs and reconstructions of the anterior cruciate ligament, posterior cruciate ligament, medial collateral ligament and posterolateral corner attempt to restore knee function by rebuilding or restoring the native anatomy. The basis of anatomic reconstruction techniques is a detailed understanding of quantitative knee anatomy. Additionally, an appreciation of the function of each component is necessary to ensure surgical success.

LEVEL OF EVIDENCE

V.

Femoral and tibial graft tunnel parameters after transtibial, anteromedial portal, and outside-in single-bundle anterior cruciate ligament reconstruction

BACKGROUND

Anatomic graft tunnel placement is recommended in anterior cruciate ligament (ACL) reconstruction to restore knee joint stability and function. Transtibial (TT), anteromedial portal (AMP), and outside-in (OI) retrograde drilling surgical techniques have been described for tibial and femoral bone tunnel preparation.

PURPOSE/HYPOTHESIS

The purpose of this study was to evaluate the bone tunnel parameters and compare the ability of 3 different surgical techniques to achieve placement of the ACL femoral and tibial bone tunnels at the center of the native ACL femoral and tibial attachment sites. The hypothesis was that tunnel placement using an AMP or OI technique would result in optimized tunnel parameters and more closely reconstruct the center of the native ACL femoral attachment site.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The study population consisted of 100 patients undergoing anatomic single-bundle ACL reconstruction using multiple-stranded hamstring tendon grafts. In group 1 (n = 36), the femoral tunnel was drilled using a TT surgical technique; in group 2 (n = 32), the femoral tunnel was drilled through an AMP; and in group 3 (n = 32), the femoral tunnel was created by use of an OI technique with retrograde drilling. Computed tomography (CT) scans were obtained postoperatively, and characteristics of femoral and tibial tunnel apertures were correlated to femoral and tibial measurement grid systems. The position of the resulting tibial and femoral bone tunnels for each group was compared with the center of the native ACL attachment sites.

RESULTS

There were statistically significant differences (P < .05) for the ACL femoral tunnel between the 3 groups with respect to intercondylar height, total tunnel length, graft fixation length, tunnel axis, and tunnel entry angle. Statistically significant differences (P < .05) were found for the ACL tibial tunnel with respect to anteroposterior tunnel position and sagittal tunnel axis between the TT and both the OI and AMP techniques. The OI surgical technique produced more oblique and anatomically correct femoral tunnel apertures and longer femoral tunnel lengths compared with the AMP technique. Both AMP and OI techniques resulted in a more precise replication of intercondylar tunnel depth and height. There was no statistically significant difference for graft fixation length between the AMP and OI techniques.

CONCLUSION

The AMP and OI surgical techniques were superior in positioning the ACL femoral tunnel at the center of the native ACL attachment site compared with the TT technique. An acceptable graft fixation length was obtained for all 3 surgical techniques.

The Apex of the Deep Cartilage: A Landmark and New Technique to Help Identify Femoral Tunnel Placement in Anterior Cruciate Ligament Reconstruction

PURPOSE

The purpose of this study was to evaluate the apex of the deep cartilage (ADC) as a landmark to help guide femoral tunnel placement during anatomic single-bundle anterior cruciate ligament (ACL) reconstruction. Our secondary purpose was to assess whether or not the endoscopic transtibial femoral offset drill guide could reach the center of the ACL's femoral footprint.

METHODS

Eight formalin-injected cadaveric knees were dissected and the center of the ACL femoral footprints identified. The ADC was selected as an easily identifiable landmark during arthroscopy and was used to reference the position of the ACL femoral footprint with the knee flexed at 90°. Next, a 7-mm transtibial femoral ACL drill guide was used to engage the posterior aspect of the lateral condyle at the level of the femoral footprint. This position was marked, and the distance from the center of the femoral footprint was recorded for each specimen. Descriptive statistics were used to report our measurements.

RESULTS

The median high and shallow measurements were 3 mm (range, 1 to 4 mm) and 12 mm (range, 11 to 17 mm), respectively. The femoral offset guide never reached the center of the femoral footprint in all specimens; the median distance between the 2 measurements was 4.5 mm (range, 2 to 9 mm).

CONCLUSIONS

If the anatomy is difficult to delineate at the time of reconstruction, our study suggests using the ADC as a landmark to guide anatomic placement. The dissection of 8 cadavers showed that the center of the ACL femoral footprint had a median position of 3 mm high and 12 mm shallow to the ADC. We also showed that the transtibial femoral offset guide did not reach the center of the ACL footprint on all specimens and should therefore not be used for anatomic ACL reconstruction.

CLINICAL RELEVANCE

Current commercially available transtibial femoral offset guides cannot reach the center of the ACL's femoral footprint and therefore should not be used. Alternative techniques, such as referencing from the ADC through an anteromedial (AM) portal, are recommended.

Variability of tunnel positioning in fluoroscopic-assisted ACL reconstruction

PURPOSE

Intraoperative fluoroscopy has been proposed as a feasible method to improve the accuracy of anatomical tunnel positioning. However, it has so far not been determined, whether this technique reduces the variability of tunnel positioning in a clinical set-up. Therefore, the purpose of this study was to determine the variability of tunnel positions applying intraoperative fluoroscopy.

METHODS

Femoral and tibial tunnel positions of 112 fluoroscopic ACL reconstruction cases were determined according to validated radiological measurement methods. Mean positions, standard deviations and ranges were calculated to determine the variability of the tunnel positions. Subgroup variability analysis was performed to analyse cases in which tunnel positions were corrected.

RESULTS

Applying intraoperative fluoroscopy, the variability of tunnel positions was found to be 3 % at the femur (range 15.4 %) and 2.3 % at the tibia (9.7 %). In 34 cases (30.0 %), non-satisfactory tunnel positions were identified and could be corrected achieving more accurate positions regarding to radiological parameters (14× femur, 16× tibia, 4× femur and tibia).

CONCLUSIONS

The results of the presented study indicate that intraoperative fluoroscopy allows to identify non-accurate tunnel positions regarding to radiological criteria. The determined low variability indicates that fluoroscopic-based ACL reconstruction can be recommended as a feasible, easy and effective adjunct that enables surgeons to create more consistent and reliable tunnel positions in ACL reconstruction.

LEVEL OF EVIDENCE

IV.

Computer-assisted anterior cruciate ligament reconstruction. Four generations of development and usage

The purpose of this paper is to review the literature about the contribution of navigation in anterior cruciate ligament (ACL) reconstruction. The evolution of computer-assisted surgery (CAS) for ACL reconstruction has undergone several steps. These steps were divided into 4 subsequent developments: (1) positioning of ACL graft placement; (2) laxity measurement of ACL reconstruction (quality control); (3) kinematic evaluation during ACL reconstruction (navigated pivot shift); (4) case-specific individual ACL reconstruction with adjustments and additional reconstruction options. CAS has shown to improve femoral tunnel positioning, even if clinical outcomes do not improve results of manual techniques. CAS technology has helped researchers better understand the effects of different ACL reconstruction techniques and bundles replacements on joint laxity and to describe tunnel positioning in relation to native ACL insertion. CAS in ACL surgery can improve results at time zero and can improve knowledge in this field.

Excursion of bone-patella tendon-bone grafts during the flexion-extension movement in anterior cruciate ligament reconstruction: Comparison between isometric and anatomic reconstruction techniques

Background/objective

The purpose of this study was to elucidate the biomechanical differences between anterior cruciate ligament (ACL) grafts reconstructed by isometric and anatomic reconstruction techniques, based on their length changes.

Methods

One hundred and thirty-three knees with primary ACL reconstruction using the bone-patellar tendon-bone (BTB) graft were retrospectively identified. Twenty-two knees and 111 knees underwent isometric round tunnel (IRT) ACL reconstruction and anatomic rectangular tunnel (ART) ACL reconstruction, respectively.

Results

After femoral-side fixation of the graft in the surgery, the length change of the graft from 120° flexion to full extension was measured by using an isometric positioner at the tibial side. Both reconstructive techniques showed little length change from 120° to ∼20° of flexion, followed by elongation of the graft, until full extension. The amount of length change of the grafts was 1.0 ± 0.7 mm with the IRT technique, and 3.4 ± 0.9 mm with the ART technique. These findings were significantly different, based on the Mann–Whitney U test (p < 0.001).

Conclusion

The native ACL has an intrinsic length change of 3–6 mm, and therefore the ART technique may more closely replicate the biomechanical function of the native ACL.

Can we use intraoperative femoral tunnel length measurement as a clue for proper femoral tunnel placement on coronal plane during ACL reconstruction?

INTRODUCTION

Successful anterior cruciate ligament (ACL) reconstruction is dependent on correct placement of both tibial and femoral tunnels. The purpose of this study is to investigate whether we can use intraoperative femoral tunnel length measurement to estimate the correct femoral tunnel placement on coronal plane.

METHODS

This prospective study comprised 164 consecutive patients who underwent ACL reconstruction surgery. Transtibial or anteromedial portal technique is used for drilling the femoral tunnels. The length of the femoral tunnel was measured during the operation. The femoral tunnel coronal plane angle was calculated on the postoperative tunnel radiographs. A statistical comparison was made of the lengths of the tunnel, the techniques used drilling and the femoral tunnel angles.

RESULTS

The far anteromedial portal was used in 81 (49%) cases and the transtibial technique in 83 (51%) cases. The mean femoral tunnel length was 42 ± 6.4 mm and the mean femoral tunnel coronal angle was 41.1° ± 11.6. The tunnel angle in the transtibial technique was determined as significantly low compared to the far anteromedial portal technique (32.6°:49.8°) and the tunnel length was significantly longer (45.8:38.1 mm) (p < 0.001). In the statistical analysis, it was found that a patient with a tunnel length of 41 mm and above had a 92.1% likelihood of femoral tunnel angle below 45°.

CONCLUSION

Femoral tunnel length can be used as a clue for intraoperative evaluation of the femoral tunnel position. If the femoral tunnel length is greater than 41 mm, the coronal plane orientation of the femoral tunnel will be improper and not at a desired position.

Review of evolution of tunnel position in anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) rupture is one of the commonest knee sport injuries. The annual incidence of the ACL injury is between 100000-200000 in the United States. Worldwide around 400000 ACL reconstructions are performed in a year. The goal of ACL reconstruction is to restore the normal knee anatomy and kinesiology. The tibial and femoral tunnel placements are of primordial importance in achieving this outcome. Other factors that influence successful reconstruction are types of grafts, surgical techniques and rehabilitation programmes. A comprehensive understanding of ACL anatomy has led to the development of newer techniques supplemented by more robust biological and mechanical concepts. In this review we are mainly focussing on the evolution of tunnel placement in ACL reconstruction, focusing on three main categories, i.e., anatomical, biological and clinical outcomes. The importance of tunnel placement in the success of ACL reconstruction is well researched. Definite clinical and functional data is lacking to establish the superiority of the single or double bundle reconstruction technique. While there is a trend towards the use of anteromedial portals for femoral tunnel placement, their clinical superiority over trans-tibial tunnels is yet to be established.

Revision single-bundle anterior cruciate ligament reconstruction with over-the-top route procedure

PURPOSE

In revision anterior cruciate ligament reconstruction (ACLR), the single-stage technique and the over-the-top route (OTTR) procedure were usually selected for cases where the bone tunnel cannot be created at an anatomical position due to tunnel enlargement and overlap with the mal-positioned tunnel of primary reconstruction. The purpose of this study was to evaluate the clinical results of revision single-bundle ACL reconstruction using OTTR procedure and to compare the clinical results of OTTR procedure with those of anatomical single-bundle revision reconstruction (SBR).

HYPOTHESIS

The results of OTTR procedure are equivalent to that of SBR.

METHODS

Seventy-six revision ACL reconstruction knees from April 2002 to December 2012 were involved in our study. We focused on 21 knees which underwent surgery with SBR and 22 knees with OTTR using hamstring tendon. The clinical results were evaluated by means of the Lysholm score and the knee stability was assessed by the Lachman test, pivot-shift test and side-to-side difference by KT-2000 pre-operatively and after 1 year post-operatively. AP translation and rotational laxity using a navigation system were evaluated before and after revision ACL reconstruction under anesthesia in 8 cases of OTTR and in 6 cases of SBR.

RESULTS

There was no statistically significant difference between the OTTR and SBR regarding Lysholm score, Lachman test, pivot-shift test, ATT by KT-2000, and AP translation and rotational laxity with a navigation system.

CONCLUSIONS

The clinical results of OTTR are almost equivalent to those of SBR. For the cases in which it is impossible to create the femoral tunnel in an anatomical position, OTTR is a valuable revision ACL reconstruction method.

LEVEL OF EVIDENCE

Case-control study. Level III.

Anterior cruciate ligament biomechanics during robotic and mechanical simulations of physiologic and clinical motion tasks: a systematic review and meta-analysis

Investigators use in vitro joint simulations to invasively study the biomechanical behaviors of the anterior cruciate ligament. The aims of these simulations are to replicate physiologic conditions, but multiple mechanisms can be used to drive in vitro motions, which may influence biomechanical outcomes. The objective of this review was to examine, summarize, and compare biomechanical evidence related to anterior cruciate ligament function from in vitro simulations of knee motion. A systematic review was conducted (2004 to 2013) in Scopus, PubMed/Medline, and SPORTDiscus to identify peer-reviewed studies that reported kinematic and kinetic outcomes from in vitro simulations of physiologic or clinical tasks at the knee. Inclusion criteria for relevant studies were articles published in English that reported on whole-ligament anterior cruciate ligament mechanics during the in vitro simulation of physiologic or clinical motions on cadaveric knees that were unaltered outside of the anterior-cruciate-ligament-intact, -deficient, and -reconstructed conditions. A meta-analysis was performed to synthesize biomechanical differences between the anterior-cruciate-ligament-intact and reconstructed conditions. 77 studies met our inclusion/exclusion criteria and were reviewed. Combined joint rotations have the greatest impact on anterior cruciate ligament loads, but the magnitude by which individual kinematic degrees of freedom contribute to ligament loading during in vitro simulations is technique-dependent. Biomechanical data collected in prospective, longitudinal studies corresponds better with robotic-manipulator simulations than mechanical-impact simulations. Robotic simulation indicated that the ability to restore intact anterior cruciate ligament mechanics with anterior cruciate ligament reconstructions was dependent on loading condition and degree of freedom examined.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

III.

Kinematic analysis of the indirect femoral insertion of the anterior cruciate ligament: implications for anatomic femoral tunnel placement

PURPOSE

To determine the effect of debriding the indirect insertion component of the femoral anterior cruciate ligament (ACL) attachment on tibiofemoral kinematics when compared with the intact knee.

METHODS

Knee kinematics were measured in 9 cadaveric knees with the ACL intact, after indirect insertion debridement, and after ACL transection. Three loading conditions were used: (1) a 134-N anterior tibial load, (2) a combined 10-Nm valgus and 5-Nm internal tibial torque, and (3) a simulated robotic pivot shift. Anterior tibial translation (ATT) was recorded in response to anterior and combined loads at 0°, 15°, 30°, 45°, 60°, and 90° of flexion. Posterior tibial translation and external tibial rotation were recorded during the simulated pivot shift.

RESULTS

With an anterior load, indirect insertion debridement increased ATT by 0.37 ± 0.24 mm at 0° (P = .002) and by 0.16 ± 0.19 mm at 15° (P = .033; increases <1 mm in all specimens). ACL transection increased ATT in response to an anterior load (P = .0001) with maximum effect at 15° compared with the intact and debrided states (11.26 ± 1.15 mm and 11.04 ± 1.08 mm, respectively). With a combined load, indirect insertion debridement increased ATT by 0.17 ± 0.11 mm at 0° (P = .001; increases <0.3 mm in all specimens) with no effect at other angles. ACL transection increased ATT in response to a combined load (P = .001) with maximum effect at 15° (4.45 ± 0.85 mm v ACL intact and 4.44 ± 0.84 mm v debrided indirect insertion). In the ACL intact condition, the pivot shift produced 1.29 ± 1.34 mm of posterior tibial translation and 1.54 ± 1.61° of external tibial rotation, as compared with 1.28 ± 1.34 mm and 1.54 ± 1.47°, respectively, after debridement (P = .68 and P = .99, respectively) and 12.79 ± 3.22 mm and 17.60 ± 4.30°, respectively, after ACL transection (P = .0001).

CONCLUSIONS

The indirect femoral ACL insertion contributes minimally to restraint of tibial translation and rotation.

CLINICAL RELEVANCE

Femoral tunnel positioning for anatomic ACL reconstruction should aim to recreate the biomechanically significant direct insertion.

Variability of tunnel positioning in ACL reconstruction

INTRODUCTION

Since tunnel positioning is one of the key factors in anterior cruciate ligament (ACL) reconstruction and the variability of tunnel positioning in ACL reconstruction has so far never been analyzed, the objective of this study was to determine the inter- and intra-observer variability of tibial and femoral tunnel positioning in ACL reconstruction.

MATERIALS AND METHODS

In an operating room setup, 13 surgeons were asked to identify the tunnel positions in one and the same ACL-deficient cadaver knee. Using a fluoroscopic based ACL navigation system, tunnel positions were digitally measured in a test/re-test scenario. For variability analysis mean positions, standard deviations and range were calculated as well as differences between test/re-test positions.

RESULTS

The intraobserver analysis showed a tibial variability of 3.3 mm (SD 2.1, range 7.5 mm) and a femoral variability of 2.0 mm (SD 1.6 mm, range 6.8 mm). The interobserver variability of the tibial tunnel positions was 3.2 mm (SD) with a range of 18.3 mm and a femoral variability of 3.7 mm (SD) with a range of 13.2 mm.

CONCLUSIONS

This study demonstrates that a reasonable inter- and intra-observer variability in ACL tunnel positioning exists even among experienced surgeons. Although deviations of 2-3 mm may seem to be acceptable at first sight, a range of up to 18.3 mm indicates that outliers exist, which can cause graft failure. More reliable reconstruction techniques should be developed to reduce the variability in tunnel positioning.

Biomechanical comparison between the rectangular-tunnel and the round-tunnel anterior cruciate ligament reconstruction procedures with a bone-patellar tendon-bone graft

PURPOSE

The purpose of this study was to evaluate the effectiveness of 2 anterior cruciate ligament (ACL) reconstruction techniques using a bone-patellar tendon-bone (BPTB) graft with femoral tunnel, either a rectangular tunnel (RET) or a round tunnel (ROT).

METHODS

For experiment 1, nine fresh-frozen human cadaveric knees were tested with a robotic/universal force-moment sensor system to determine the initial optimal tension: the amount of graft tension at 15° of flexion most closely resembling the anterior laxity of a normal knee. The value was estimated by repeatedly measuring anterior laxity when 100 N of anteroposterior drawer load was applied to the knees at 30° of flexion after RET ACL or ROT ACL reconstruction. For experiment 2, six fresh-frozen human cadaveric knees were selected. On the basis of the initial tension determined in experiment 1, RET ACL reconstruction was conducted with the graft tensioned to 10 N, followed by ROT ACL reconstruction on the same knee at 40 N of initial tension, and the biomechanical efficacy of the 2 methods was compared.

RESULTS

For experiment 1, the mean laxity match tension at 15° of flexion was 8.6 ± 4.8 N and 34.8 ± 9.2 N for RET- and ROT-reconstructed knees, respectively. For experiment 2, both RET and ROT ACL reconstructions were successful in controlling anterior tibial translation under anterior tibial loads, with the graft initially tensioned to 10 N in the former and to 40 N in the latter. However, the greater tensioning in ROT reconstruction led to proximal, posterior, and lateral displacement of the tibia along with its external and valgus rotation.

CONCLUSIONS

The RET ACL-reconstructed knee more closely resembled the normal knee in biomechanical behavior. Although ROT reconstruction successfully controlled anterior translation with greater initial tensioning to the graft, the normal positional relation between the tibia and femur was impaired.

CLINICAL RELEVANCE

Rectangular femoral ACL fixation constructs and grafts may prove more efficacious at restoring in vivo ACL kinematics than round femoral tunnels.

In vivo kinematic evaluation of anatomic double-bundle anterior cruciate ligament reconstruction

BACKGROUND

There is controversy regarding the functional role of the posterolateral (PL) bundle of the anterior cruciate ligament (ACL).

PURPOSE

To evaluate the in vivo function of the PL and anteromedial (AM) bundles of the ACL during anatomic double-bundle (DB) ACL reconstruction for acute, isolated ACL tears utilizing a computer navigation system to track intraoperative knee kinematics.

STUDY DESIGN

Controlled laboratory study.

METHODS

Fifteen patients with acute, isolated ACL tears who underwent anatomic DB ACL reconstruction formed the sample for this study. During surgery, knees were examined by a clinician preoperatively, after fixation of the PL bundle, and after fixation of both the PL and AM bundles. An image-free computer navigation system with custom-made software recorded the data during kinematic tests. The examination consisted of the Lachman and anterior drawer tests, internal-external rotation at 30° of knee flexion, and varus-valgus rotation at 30° of knee flexion. Paired Wilcoxon tests were performed to evaluate the effects of each bundle. The comparisons included ACL-deficient to PL bundle-reconstructed knees, ACL-deficient to DB ACL-reconstructed knees, and PL bundle-reconstructed to DB ACL-reconstructed knees. Significance was set at P < .017 to account for the multiple comparisons.

RESULTS

Fixation of the PL bundle significantly improved knee laxity during the Lachman and anterior drawer tests as well as internal-external rotation at 30° of knee flexion (P < .017 for all tests). The addition of the AM bundle further improved knee laxity during the Lachman and anterior drawer tests compared with PL bundle fixation as well as during varus-valgus rotation at 30° of knee flexion compared with ACL-deficient knees (P < .017 for all tests).

CONCLUSION

This in vivo study demonstrates that isolated PL bundle reconstruction improves laxity in an ACL-deficient knee and that the addition of the AM bundle improves laxity parameters further.

CLINICAL RELEVANCE

Abnormal knee kinematics is known to be linked to the earlier onset of osteoarthritis and lower rates of return to sport. This study suggests that both the AM and PL bundles are important to stabilize ACL-deficient knees.

Clinical outcome of anatomic double-bundle ACL reconstruction and 3D CT model-based validation of femoral socket aperture position

PURPOSE

The purpose of this study was to evaluate the clinical results of anatomic double-bundle (DB) anterior cruciate ligament (ACL) reconstruction in which anatomic position of femoral socket apertures was validated using three-dimensional (3D) computed tomography (CT) modelling.

METHODS

Anatomic DB ACL reconstructions with hamstring autografts were performed in 34 patients. Two femoral sockets were created through a far anteromedial (AM) portal behind the lateral intercondylar ridge with the assistance of intraoperative 3D fluoroscopic navigation. Femoral tunnel aperture positioning was investigated postoperatively using 3D CT images in all patients. Clinical results were also evaluated subjectively and objectively at least up to 2 years.

RESULTS

Measurement of the AM and the posterolateral (PL) femoral socket locations on the 3D CT images using the quadrant method showed that the centre of the AM socket aperture was located at a depth of 21.0 ± 4.1% and a height of 30.5 ± 9.3% and that of the PL socket aperture was located at a depth of 31.3 ± 5.8% and a height of 57.2 ± 7.7%. The femoral socket locations were considered as anatomic in accordance with previous cadaveric studies examining the positions of ACL femoral insertion site. Subjectively, the mean Lysholm score was 96.9 ± 4.0 points. According to IKDC final objective scores, 26 knees (76%) were objectively graded as normal, 8 (24%) as nearly normal, and 0 (0%) as abnormal or severely abnormal. Postoperative side-to-side anterior translation measured with a KT-2000 arthrometer averaged 0.7 ± 1.2 mm.

CONCLUSIONS

DB ACL reconstructions in which femoral socket apertures were validated anatomically using 3D CT provided satisfactory short-term results.

LEVEL OF EVIDENCE

Case series, Level IV.

A comparison of the anteromedial and transtibial drilling technique in ACL reconstruction after a short-term follow-up

INTRODUCTION

The purpose of this study was to compare clinical and radiological outcomes of patients who underwent single-bundle anterior cruciate ligament (ACL) reconstruction with anteromedial portal (AMP) and transtibial (TT) techniques.

MATERIALS AND METHODS

Arthroscopic single-bundle ACL reconstruction was performed using AMP technique in 34 patients and TT technique in 30 patients. The patients were evaluated retrospectively. Aperture fixation was used for femoral fixation, and absorbable screws and U staples were used for tibial fixation of the graft. Pivot shift test, Lachman test, Lysholm, Tegner, and International Knee Documentation Committee (IKDC-2000) scoring systems were used in the clinical and functional evaluation of patients before and after the surgery. Time to return sports and activity level were assessed. In the radiological evaluation of non-anatomic bone tunnel placement, the criteria developed by lllingworth et al. were used. The mean duration of follow-up was 20.4 and 24.6 months in the AMP and TT groups, respectively.

RESULTS

There was a significant difference between the AMP group (86.7 %) and the TT (14.7 %) group in terms of anatomical placement of the femoral tunnels and grafts (p < 0.001). No significant difference was observed between the two groups in terms of the Pivot shift test, Lachman test, Lysholm, Tegner, and IKDC scores, and activity level (p > 0.05). The patients in the AMP group returned to sports 1.5 months earlier on average (p < 0.001).

CONCLUSIONS

It was shown that AMP technique was superior to the TT technique in providing anatomical placement of the graft and in recovery time to return sports; however, there was no difference between groups in early periods in terms of the clinical and functional outcomes.

Eccentric femoral tunnel widening in anatomic anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to retrospectively evaluate femoral tunnel widening (TW) and migration of the femoral tunnel aperture after anatomic anterior cruciate ligament (ACL) reconstructions with hamstring grafts and bone-patellar tendon-bone (BPTB) grafts.

METHODS

Of the 105 consecutive patients who underwent ACL reconstruction, the 52 patients who underwent isolated ACL reconstruction and in whom tunnel measurement could be obtained by computed tomography were included in this study. In 26 patients, double-bundle reconstruction (DBR) of the ACL using hamstring tendons was performed. These patients were compared with 26 patients in whom rectangular tunnel ACL reconstruction using BPTB grafts (BPTBR) was performed. Femoral tunnel aperture positioning and TW were investigated postoperatively using 3-dimensional computed tomographic images, which were performed a week and a year after surgery in all patients.

RESULTS

In DBR, the average diameter of the anteromedial (AM) femoral tunnel increased by 34.0% in the horizontal direction and 28.2% in the vertical direction, whereas that of the posterolateral (PL) femoral tunnel increased by 58.2% and 73.4%, respectively, at 1 year after surgery compared with 1 week after surgery. The percentage TW value of the PL tunnel was significantly greater than that of the AM tunnel. In BPTBR, the average diameter increased by 22.0% and 17.1%, respectively. The percentage TW value of the PL tunnel in DBR was significantly greater than that of the femoral tunnel in BPTBR. Each tunnel aperture migrated distally ("shallow") in the horizontal direction and high in the vertical direction. AM and PL tunnel apertures in DBR migrated in the vertical direction significantly more than they did in BPTBR. No significant differences between the 2 groups were found in clinical outcomes.

CONCLUSIONS

The femoral PL tunnel aperture in DBR showed significantly more widening than did the AM tunnel aperture in DBR and the femoral tunnel aperture in BPTBR. Also, greater migration of the femoral tunnel aperture in the vertical direction because of TW was observed in DBR than in BPTBR.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Anatomic single- versus double-bundle ACL reconstruction: a meta-analysis

PURPOSE

To determine whether anatomic double-bundle anterior cruciate ligament (ACL) reconstruction compared to anatomic single-bundle ACL reconstruction more effectively restored antero-posterior (A-P) laxity, rotatory laxity and reduced frequency of graft rupture. Our hypothesis was that anatomic double-bundle ACL reconstruction results in superior rotational knee laxity and fewer graft ruptures due to its double-bundle tension pattern, compared with anatomic single-bundle ACL reconstruction.

METHODS

An electronic search was performed using the PubMed, EMBASE and Cochrane Library databases. All therapeutic trials written in English reporting knee kinematic outcomes and graft rupture rates of primary anatomic double- versus single-bundle ACL reconstruction were included. Only clinical studies of levels I-II evidence were included. Data regarding kinematic tests were extracted and included pivot-shift test, Lachman test, anterior drawer test, KT-1000 measurements, A-P laxity measures using navigation and total internal-external (IRER) laxity measured using navigation, as well as graft failure frequency.

RESULTS

A total of 7,154 studies were identified of which 15 papers (8 randomized controlled trials and 7 prospective cohort studies, n = 970 patients) met the eligibility criteria. Anatomic ACL double-bundle reconstruction demonstrated less anterior laxity using KT-1000 arthrometer with a standard mean difference (SMD) = 0.36 (95% CI 0.214-0.513, p < 0.001) and less A-P laxity measured with navigation (SMD = 0.29 95% CI 0.01-0.565, p = 0.042). Anatomic double-bundle ACL reconstruction did not lead to significant improvements in pivot-shift test, Lachman test, anterior drawer test, total IRER or graft failure rates compared to anatomic single-bundle ACL reconstruction.

CONCLUSION

Anatomic double-bundle ACL reconstruction is superior to anatomic single-bundle reconstruction in terms of restoration of knee kinematics, primarily A-P laxity. Whether these improvements of laxity result in long-term improvement of clinical meaningful outcomes remains uncertain.

LEVEL OF EVIDENCE

II.

A comparison of dynamic rotational knee instability between anatomic single-bundle and over-the-top anterior cruciate ligament reconstruction using triaxial accelerometry

PURPOSE

Recently, single-bundle (SB) anterior cruciate ligament (ACL) reconstruction has been advanced by the anatomic concept, but the biomechanical outcome of the anatomic method has not been fully investigated, especially for rotational instability. Anatomic SB and the single over-the-top procedures are the treatment of choice for primary cases and revision or skeletally immature cases, respectively. The purpose of this study was to investigate the dynamic rotational instability of anatomic SB and over-the-top reconstruction during a pivot shift test using triaxial accelerometry.

METHODS

Eight fresh frozen human cadaveric knees were used in this study. Rotational instability measurement was conducted during a pivot shift test by the use of a triaxial accelerometer attached to the tibia. The tests were performed in the ACL-intact, ACL-deficient and ACL-reconstructed knees with two different procedures (anatomic SB and over-the-top). The acceleration in three directions and the magnitude of acceleration were measured to evaluate rotational instability and compare between four different knee states.

RESULTS

The overall magnitude of acceleration was significantly different (P < 0.01) between the ACL-intact knees and the ACL-deficient knees. Both anatomic SB and over-the-top ACL reconstruction significantly reduced the overall magnitude of acceleration compared to the ACL-deficient knees, but still had larger accelerations compared to the ACL-intact knees. There was no significant difference for the overall magnitude of acceleration between anatomic SB and over-the-top reconstruction procedure.

CONCLUSION

Over-the-top reconstruction provides comparable result to anatomic SB reconstruction in terms of controlling the dynamic rotational stability. Over-the-top reconstruction might be one of the options for revision cases and in skeletally immature patients.

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.

Low inter- and intraobserver variability allows for reliable tunnel measurement in ACL reconstruction using the quadrant method

INTRODUCTION

Correct anatomic tunnel positions are essential in anterior cruciate ligament (ACL) reconstruction. To establish recommendations for tunnel positioning based on anatomical findings and to compare tunnel positions with clinical results, different radiological measurement methods as the quadrant method exist. Comparing the data of different observers requires the validation of the reliability of measurement methods. The purpose of this study therefore was to determine the reliability of the quadrant method to measure tunnel positions in ACL reconstruction. The hypothesis was, that the quadrant method shows a low inter- and intraobserver variability.

MATERIALS AND METHODS

In a test/retest scenario 20 knee surgeons were asked to determine defined tunnel positions in five lateral radiographs applying the quadrant method. Rotation, angle deviation, height and depth of the quadrant as well as absolute and relative tunnel positions of each observation were measured along referenced scales. Mean sizes and angle deviations of the quadrants, tunnel positions and deviations between the test/retest positions were calculated as well as standard deviations and range.

RESULTS

Interobserver variability analyses, to plan as well as to determine tunnel positions in ACL reconstruction, showed a mean variability (SD) of <1 mm, with ranges of 2.5 mm for planning and 3.7 mm for determination of tunnel positions using the quadrant method. Intraobserver analysis showed mean variability with deviations of <1 mm and maximum standard deviations of 0.7 mm and ranges of up to 2.3 mm.

CONCLUSIONS

We confirmed the hypothesis that the quadrant method has a low inter- and intraobserver variability. Based on the presented validation data, the quadrant method can be recommended as reliable method to radiographically describe insertion areas of the ACL as well as to determine tunnel positions in ACL reconstruction intra and postoperatively.

Implant-free ACL reconstruction: a review

Implant-free anterior cruciate ligament (ACL) reconstruction is the fixation of ACL grafts without the need for artificial implants. Our aim was to study the evolution of this technique, review the biomechanical evidence and summarise the results. Implant-free graft fixation for bone patella tendon ACL reconstruction was first described in 1987. This concept of implant-free graft fixation was adapted for hamstring and quadriceps tendons as alternative graft sources. Various biomechanical studies have reported that by adhering to certain technical details, this technique provides comparable fixation strength as conventional ACL fixation. The outcome studies of implant-free ACL reconstruction also report clinical results similar to ACL reconstruction with conventional implants.

In vivo three-dimensional imaging analysis of femoral and tibial tunnel locations in single and double bundle anterior cruciate ligament reconstructions

BACKGROUND

Anatomic footprint restoration of anterior cruciate ligament (ACL) is recommended during reconstruction surgery. The purpose of this study was to compare and analyze the femoral and tibial tunnel positions of transtibial single bundle (SB) and transportal double bundle (DB) ACL reconstruction using three-dimensional computed tomography (3D-CT).

METHODS

In this study, 26 patients who underwent transtibial SB ACL reconstruction and 27 patients with transportal DB ACL reconstruction using hamstring autograft. 3D-CTs were taken within 1 week after the operation. The obtained digital images were then imported into the commercial package Geomagic Studio v10.0. The femoral tunnel positions were evaluated using the quadrant method. The mean, standard deviation, standard error, minimum, maximum, and 95% confidence interval values were determined for each measurement.

RESULTS

The femoral tunnel for the SB technique was located 35.07% ± 5.33% in depth and 16.62% ± 4.99% in height. The anteromedial (AM) and posterolateral (PL) tunnel of DB technique was located 30.48% ± 5.02% in depth, 17.12% ± 5.84% in height and 34.76% ± 5.87% in depth, 45.55% ± 6.88% in height, respectively. The tibial tunnel with the SB technique was located 45.43% ± 4.81% from the anterior margin and 47.62% ± 2.51% from the medial tibial articular margin. The AM and PL tunnel of the DB technique was located 33.76% ± 7.83% from the anterior margin, 45.56% ± 2.71% from the medial tibial articular margin and 53.19% ± 3.74% from the anterior margin, 46.00% ± 2.48% from the medial tibial articular margin, respectively. The tibial tunnel position with the transtibial SB technique was located between the AM and PL tunnel positions formed with the transportal DB technique.

CONCLUSIONS

Using the 3D-CT measuring method, the location of the tibia tunnel was between the AM and PL footprints, but the center of the femoral tunnel was at more shallow position from the AM bundle footprint when ACL reconstruction was performed by the transtibial SB technique.

Anatomic, arthroscopically assisted, mini-open fibular collateral ligament reconstruction: an in vitro biomechanical study

BACKGROUND

The fibular collateral ligament (FCL) is the primary restraint to varus rotation of the knee joint. Arthroscopic techniques are widely used and minimally invasive, but anatomic arthroscopic reconstruction of an isolated FCL injury has not been reported.

HYPOTHESIS

Anatomic reconstruction of an isolated FCL injury can be performed arthroscopically and will restore the knee to near-normal stability.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 12 nonpaired, fresh-frozen cadaveric knees were biomechanically subjected to a 10-N·m varus moment and 5-N·m external and internal rotation torques at 0°, 15°, 30°, 60°, 90°, and 120° of knee flexion, respectively (0° only for varus loading). Testing was performed with an intact and sectioned FCL and also after an anatomic reconstruction of the FCL by arthroscopic technique. Kinematics of each knee under various loading conditions was determined with a robotic universal force/moment sensor testing system.

RESULTS

After sectioning, significant increases were found in varus rotation at 0°, 15°, 30°, 60°, 90°, and 120° of knee flexion; in external rotation at 15°, 30°, and 60° of knee flexion; and in internal rotation at 30°, 60°, and 90° of knee flexion. After reconstruction, full recovery of knee stability was observed in varus rotation at 0°, 15°, 30°, and 60°; in external rotation at 0°, 15°, 30°, 60°, 90°, and 120°; and in internal rotation at 0°, 15°, 30°, 60°, 90°, and 120°. When the sectioned and intact FCL knee conditions were compared, significant increases of 3.4° at 90° of flexion and 3.4° at 120° of flexion were found (P < .001, both conditions); when the reconstructed and sectioned FCL knee conditions were compared, significant decreases of 1.7° at 90° of flexion and 1.7° at 120° of knee flexion were found (P = .033 and .043, respectively).

CONCLUSION

An anatomic reconstruction of the FCL can be performed by an arthroscopically assisted mini-open technique with an isolated FCL injury, and near-normal stability of the knee can be restored.

CLINICAL RELEVANCE

Anatomic reconstruction of the FCL by an arthroscopically assisted mini-open technique is a viable, less invasive option to treat nonrepairable isolated FCL injury.

The influence of femoral tunnel position in single-bundle ACL reconstruction on functional outcomes and return to sports

PURPOSE

The purpose of this study was to radiographically investigate the influence of femoral tunnel placement in ACL reconstruction on early outcomes and return to sports due to anatomic and nonanatomic positioning.

METHODS

A prospective study was conducted from 2008 to 2010, with 86 athletes who underwent ACL reconstruction between anteromedial (AM) footprint and high AM position. Knee functional outcomes (IKDC objective and subjective, Tegner score, and Lysholm scale) return to sports and complications were analyzed at 6- and 12-month follow-up.

RESULTS

At follow-up, it was observed that tunnel projection along Blumensaat's line was correlated with functional outcomes on Tegner scale (at 6 and 12 months) and IKDC subjective (at 12 months). There was a significant difference in mean tunnel projection along Blumensaat's line when analyzing return to sports (73 ± 1.4 and 79 ± 1.7 %, respectively, for projections on return vs. no return to sports, p = 0.02) and complications (73 ± 1.3 vs. 78 ± 1.6 %, respectively, for projections on no complications vs. complications, p = 0.03). No differences were stated on coronal view. These correlations between tunnel positioning on functional outcomes could not be explained by demographic or baseline characteristics.

CONCLUSION

The clinical relevance of this study is that tunnel positioning along AM footprint and high AM position represented by tunnel projection along Blumensaat's line is associated with early return to sports on previous Tegner level and better functional outcome in athletes.

Correlation between femoral tunnel length and tunnel position in ACL reconstruction

BACKGROUND

The position of the femoral tunnel affects the osseous geometry available for drilling during anterior cruciate ligament (ACL) reconstruction. The length of the tunnel changes with changes in the tunnel position and may have implications for femoral fixation.

METHODS

Forty-seven patients with a single-bundle ACL reconstruction underwent computed tomography (CT) evaluation to generate three-dimensional (3D) CT bone models. With use of a previously described anatomic coordinate system, the center of the femoral tunnel was quantified in the posterior-anterior and proximal-distal dimensions on 3D CT. Tunnel length was defined as the distance between the centers of the intra-articular and extra-articular tunnel apertures. The reconstructed knees were dichotomized by anatomy and technique into anatomic (n = 20) and nonanatomic (n = 27) groups as well as according to whether they had undergone medial portal drilling (n = 20) or transtibial drilling (n = 27) for analysis. In addition, a review of the literature on the relationship between tunnel length and tendon-to-bone healing was performed.

RESULTS

Femoral tunnels drilled with nonanatomic footprints were longer (mean [and standard deviation], 43.6 ± 8.5 mm; range, 28.2 to 60.7 mm) than tunnels drilled with anatomic footprints (31.0 ± 6.3 mm; 21.2 to 42.5 mm) (p &lt; 0.001). Tunnels drilled transtibially (44.4 ± 7.6 mm; 32.5 to 60.7 mm) were significantly longer than tunnels drilled through the medial portal (29.8 ± 5.0 mm; 21.2 to 40.3 mm) (p &lt; 0.001). There was a strong correlation between tunnel length and posterior-anterior femoral tunnel position (r = 0.78, p &lt; 0.05), with more anterior tunnel positioning associated with greater tunnel length. There was no correlation between posterior-distal femoral tunnel position and tunnel length (r = -0.05; p = 0.74). There was no consensus in the literature regarding adequate tunnel length for biologic fixation.

CONCLUSIONS

Femoral tunnels drilled with anatomic footprints had sufficient length for adequate femoral fixation. Femoral tunnels positioned anterior to the native insertion of the ACL were longer than those in anatomic position.

CLINICAL RELEVANCE

The results of this study can help the surgeon to consider the relationship between tunnel position and subsequent tunnel length in ACL reconstruction.

Transtibial versus independent drilling techniques for anterior cruciate ligament reconstruction: a systematic review, meta-analysis, and meta-regression

BACKGROUND

While numerous cadaveric, in vivo, and clinical studies have compared transtibial and independent drilling of femoral tunnels during anterior cruciate ligament reconstruction, there is no evidence-based consensus on which technique affords the best outcome.

HYPOTHESIS

There is no difference in clinical outcome between transtibial and independent drilling of femoral tunnels.

STUDY DESIGN

Systematic review with meta-analysis and meta-regression.

METHODS

Cadaveric, in vivo, and clinical studies comparing transtibial and independent drilling techniques were systematically identified. A qualitative synthesis of nonrandomized studies and meta-analysis of randomized controlled trials (RCTs) were performed. In addition, a meta-regression analysis of RCTs that did not directly compare drilling techniques was performed.

RESULTS

A total of 49 studies were included in the qualitative review, and 15 were included in the meta-analysis; 22 studies were included in the meta-regression. In biomechanical studies, independent drilling placed the center of the femoral tunnel closer to the center of the femoral footprint (mean difference, 2.69 mm; 95% CI, 0.46-4.92; P < .00001). Independent drilling reduced anterior tibial translation with the Lachman examination (mean difference, 2.2 mm; 95% CI, 0.34-4.07; P = .02), 134 N of anterior load (mean difference, 1 mm; 95% CI, 0.29-1.71; P = .006), and simulated pivot shift (mean difference, 3.36 mm; 95% CI, 1.88-4.85; P < .00001). The meta-analysis showed improved Lysholm scores with independent drilling (mean difference, -0.62 points; 95% CI, -1.09 to -0.55; P = .009), although the clinical relevance of this small difference is questionable. There were no significant differences in International Knee Documentation Committee (IKDC) objective scores or Tegner scores between groups. With the meta-regression, there were no significant differences in failure rates or IKDC objective scores.

CONCLUSION

While there are biomechanical data suggesting improved knee stability and more anatomic graft placement with independent drilling, no significant clinical differences were found between the 2 techniques.

CLINICAL RELEVANCE

The current evidence shows that transtibial and independent drilling techniques have equivalent clinical outcomes at short-term to midterm follow-up. The long-term effects of subtle differences in tunnel position and postoperative knee kinematics should be further studied in dedicated, prospective cohort and randomized studies.

Accuracy of a computer-assisted planning and placement system for anatomical femoral tunnel positioning in anterior cruciate ligament reconstruction

BACKGROUND

Femoral tunnel positioning is a difficult, but important factor in successful anterior cruciate ligament (ACL) reconstruction. Computer navigation can improve the anatomical planning procedure besides the tunnel placement procedure.

METHODS

The accuracy of the computer-assisted femoral tunnel positioning method for anatomical double bundle ACL-reconstruction with a three-dimensional template was determined with respect to both aspects for AM and PL bundles in 12 cadaveric knees.

RESULTS

The accuracy of the total tunnel positioning procedure was 2.7 mm (AM) and 3.2 mm (PL). These values consisted of the accuracies for planning (AM:2.9 mm; PL:3.2 mm) and for placement (about 0.4 mm). The template showed a systematic bias for the PL-position.

CONCLUSIONS

The computer-assisted templating method showed high accuracy for tunnel placement and has promising capacity for application in anatomical tunnel planning. Improvement of the template will result in an accurate and robust navigation system for femoral tunnel positioning in ACL-reconstruction.

Coverage of the anterior cruciate ligament femoral footprint using 3 different approaches in single-bundle reconstruction: a cadaveric study analyzed by 3-dimensional computed tomography

BACKGROUND

Performing a single-bundle anterior cruciate ligament (ACL) reconstruction within the femoral footprint is important to obtain a functional graft and a stable knee.

HYPOTHESIS

There will be a significant difference in the ability of 3 ACL reconstruction techniques to reach and cover the native femoral footprint.

STUDY DESIGN

Controlled laboratory study.

METHODS

The percentage of the ACL footprint covered by the femoral tunnel was compared after 3 different techniques to target the footprint: transtibial (TT), inside-out/anteromedial (IO), and outside-in/transfemoral (OI). Fourteen cadaveric knee specimens with a mean age of 67.5 years were used. For each knee, the TT technique utilized a 7.5-mm offset guide, the IO technique was performed through an accessory anteromedial portal, and the OI technique was carried out through the femur from the external wall of the lateral condyle. Entry points in the footprint were spotted with markers, and orientations (sagittal and frontal) of each drill guide were noted. The distal femurs were sawed and scanned, and 3-dimensional image reconstructions were analyzed. The virtual drilled area (reamer diameter, 8 mm) depending on the entry point and the sagittal/frontal orientation of the drill guide was calculated and reported for each of the 3 techniques. The distance from the tunnel center to the ACL center, percentage of the femoral tunnel within the ACL footprint, and percentage of the ACL footprint covered by the tunnel were calculated and statistically compared (analysis of variance and t test).

RESULTS

The average distance to the native femoral footprint center was 6.8 ± 2.68 mm for the TT, 2.84 ± 1.26 mm for the IO, and 2.56 ± 1.39 mm for the OI techniques. Average percentages of the femoral tunnel within the ACL footprint were 32%, 76%, and 78%, and average percentages of the ACL footprint covered by the tunnel were 35%, 54%, and 47%, for the TT, IO, and OI techniques, respectively. No significant difference was observed between the IO and OI techniques (P = .11). The TT approach gave less satisfactory coverage on all testing criteria.

CONCLUSION

The IO and OI techniques allowed for creation of a tunnel closest to the ACL femoral footprint center. Despite this fact and even if the average percentage of the drilled area included in the femoral footprint was close to 80% for these 2 techniques, the average percentage of the ACL footprint covered by the tunnels was <55% for all 3 techniques. Coverage of the ACL footprint depended on the entry point, orientation, and diameter of the drilling but also on the size of the footprint.

CLINICAL RELEVANCE

To improve the coverage of the native femoral footprint with a single-bundle graft, in addition to the entry point it may also be necessary to consider the orientation of the drilling to increase the dimensions of the area while respecting the anatomic constraints of the femoral bone and graft geometry.

Passive anterior tibial subluxation in anterior cruciate ligament-deficient knees

BACKGROUND

Abnormal anterior-posterior and rotational motion secondary to anterior cruciate ligament (ACL) insufficiency is typically described in terms of dynamic laxity. An original description of the abnormal tibiofemoral relationship in the setting of ACL insufficiency has highlighted the presence of a fixed anterior tibial subluxation in this population of failed ACL reconstruction (ACLR); however, no study has quantified the degree of tibial subluxation in both the medial and lateral compartments.

PURPOSE

To measure and compare the amount of anterior tibial subluxation among various states of ACL competency, including (1) intact ACL, (2) acute ACL disruption, and (3) failed ACLR (ie, patients requiring revision ACLR). We hypothesized that anterior tibial displacement would be greater in the lateral compartment and in cases of failed ACLR compared with intact and acute ACL injured states.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Using sagittal magnetic resonance imaging (MRI) and a standardized measurement technique, we determined the amount of anterior tibial subluxation relative to a constant posterior condylar reference point. Measurements were performed in both the medial and the lateral compartments and were compared with 1-way analysis of variance. The presence of meniscal tears along with meniscal volume loss and chondral damage was correlated with the amount of subluxation in each group.

RESULTS

Compared with the intact ACL state, the medial tibial plateau was positioned more anteriorly relative to the femur in both acute ACL injured knees (mean 1.0 mm) and those that failed ACLR (mean 1.8 mm) (P = .072). In the lateral compartment, there was 0.8 mm of mean anterior tibial displacement after acute ACL injury and 3.9 mm of mean anterior subluxation in patients who failed ACLR (P < .001). Mean anterior displacement of the lateral plateau in patients who failed ACLR was almost 5 times greater than the amount observed in patients with acute ACL injuries. There was no correlation between meniscal/chondral injury and the amount of subluxation.

CONCLUSION

Patients who require revision ACLR have an abnormal tibiofemoral relationship noted on MRI that is most pronounced in the lateral compartment and should be taken into account during revision surgery. These observations may explain the suboptimal clinical results seen in some patients who undergo revision ACLR.

Long-term results after reconstruction of the ACL with hamstrings autograft and transtibial femoral drilling

PURPOSE

To evaluate the long-term clinical, patient-reported and radiological outcome of patients reconstructed for anterior cruciate ligament (ACL) insufficiency. We wanted to examine the relationship between clinical findings and patient-reported scores.

METHODS

The 96 first successive patients that underwent ACL reconstruction using transtibial technique, hamstrings autograft and tunnel placement ad modum Howell were evaluated 10 years post-operatively. Subjective outcomes were Lysholm score, IKDC 2000 subjective score and Tegner activity scale. The clinical examination included evaluation of rotational and sagittal laxity. Evaluation of osteoarthritis was done radiologically.

RESULTS

Eighty-three patients (86%) were available for follow-up at mean 10.2 years post-operatively. Three patients had revision ACL surgery prior to the 10-year evaluation. The mean Lysholm score, subjective IKDC 2000 score and Tegner activity scale were 89 (SD 13), 83 (SD 15) and 5 (range, 3-9), respectively. Six patients (8%) had moderate or severe osteoarthritis. Eighty-six per cent of patients had normal or near-normal anterior-posterior ACL laxity. Twenty per cent of patients had positive pivot shift and 42 % had a pivot glide. The former group had a significant lower Lysholm score compared to the rest of the patients.

CONCLUSIONS

Although the mean Lysholm score was classified as good (89) at the 10-year follow-up, a positive pivot shift was found in 20% of these patients. Compared to patients with normal rotational laxity or pivot glide, this patient group reported significant lower subjective satisfaction at the long-term follow-up.

LEVEL OF EVIDENCE

Case series, level IV.