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

Contact area between femoral tunnel and interference screw in anatomic rectangular tunnel ACL reconstruction: a comparison of outside-in and trans-portal inside-out techniques

PURPOSE

The purpose of this study was to compare the femoral tunnel length, the femoral graft bending angle at the femoral tunnel aperture, and the contact area between the femoral tunnel wall and an interference screw used for fixation in anatomic rectangular tunnel anterior cruciate ligament (ACL) reconstruction (ART ACLR).

METHODS

The study included 149 patients with primary ACL injury who underwent ART ACLR. Preoperatively, flexion angle of the index knee was checked under general anaesthesia. Those of less than 130° of passive flexion were assigned to the outside-in (OI) technique (78 patients), while the others to the trans-portal inside-out (TP) technique (71 patients). The patients underwent computed tomography with multiplanar reconstruction at 3-5 weeks post-operatively. Femoral tunnel length, graft bending angle, and contact ratio between the IFS and femoral tunnel were assessed. P < 0.05 was considered statistically significant.

RESULTS

The femoral tunnel length in the OI technique was significantly longer than that in the TP technique (P < 0.001). The femoral graft bending angle in the OI technique was significantly more acute than that in the TP technique (P < 0.001). The contact ratio in the OI technique was significantly larger than that in the TP technique at every point in the femoral tunnel (P < 0.001).

CONCLUSIONS

The OI technique resulted in a more acute femoral graft bending angle, longer mean femoral tunnel length, and larger contact ratio than the TP technique after ART ACLR.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

Can we predict the size of frequently used autografts in ACL reconstruction?

PURPOSE

This study presents a method to measure the size of quadriceps, patellar tendon and hamstring autografts using preoperative magnetic resonance imaging (MRI).

METHODS

Sixty-two subjects with a mean age of 25 ± 10 years who underwent ACL surgery between 2011 and 2014 were included. Patient anthropometric data were recorded for all subjects. During surgery, the respective autograft was harvested and measured using commercially available graft sizers. MRI measurements were performed by two raters, who were blinded to the intra-operative measurements.

RESULTS

The inter- and intra-rater reliability was ≥0.8 for all MRI measurements. The intra-class correlation coefficient between the MRI measurement of the graft and the actual size of the harvested graft was 0.639. There were significant correlations between quadriceps tendon thickness and height (r = 0.3, p < 0.03), weight (r = 0.3, p < 0.01), BMI (r = 0.3, p < 0.04) and gender (r = -0.4, p < 0.002) and patellar tendon thickness and height (r = 0.4, p < 0.01), weight (r = 0.3, p < 0.01) and gender (r = -0.4, p < 0.012).

CONCLUSION

Preoperative MRI measurements of quadriceps, patellar tendon and hamstring graft size are highly reliable with moderate-to-good accuracy. Significant correlations between patient anthropometric data and the thicknesses of the quadriceps and patellar tendons were observed. Obtaining this information can be useful for preoperative planning and to help counsel patients on appropriate graft choices prior to surgery.

LEVEL OF EVIDENCE

III.

Three-Dimensional Evaluation of Similarity of Right and Left Knee Joints

Purpose

The purpose of this study was to evaluate the anatomical similarity of three-dimensional (3D) morphometric parameters between right and left knees.

Materials and Methods

Ten fresh-frozen paired cadaveric knees were tested. Following dissection, footprint areas of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) were measured. Surface scanning was performed using a 3D scanner. Scanned data were reproduced and morphometric parameters were measured on specialized software. After making mirror models, we compared footprint center positions of the ACL and PCL of both sides and calculated the average deviation of 3D alignment between the right- and left-side models.

Results

No significant side-to-side differences were found in any morphometric parameters. Bony shapes displayed a side-to-side difference of <1 mm. Distal femoral and proximal tibial volumes did not present side-to-side differences, either; the average 3D deviations of alignment between the right and left sides were 0.8±0.4/1.1±0.6 mm (distal femur/proximal tibia). Center-to-center distances between the right and left ACL footprints were 2.6/2.7 mm (femur/tibia) for the anteromedial bundle and 2.4/2.8 mm for the posterolateral bundle. They were 1.9/1.5 mm for the anterolateral bundle and 2.2/1.8 mm for the posteromedial bundle of the PCL.

Conclusions

There was a remarkable 3D morphometric similarity between right and left knees. Our results might support the concept of obtaining morphologic reference data from the uninvolved contralateral knee.

Torsional Appearance of the Anterior Cruciate Ligament Explaining "Ribbon" and Double-Bundle Concepts: A Cadaver-based Study

PURPOSE

To investigate the effect of the anterior cruciate ligament (ACL) torsion in 90° knee flexion on the morphological appearance of the ACL.

METHODS

Sixty knees from fresh frozen anatomical specimens were dissected. Eighteen knees were excluded according to selection criteria (torn ACL, mucoid degeneration of the ACL, arthritic lesions of the notch, or knees harboring synovial inflammatory pathologies). After the removal of the synovial membrane, the morphology of the ligamentous fibers of the ACL and the twist were analyzed. Twisting of the ACL was measured using a goniometer in 90° knee flexion and defined by the angle of external rotation of the femur on the axis of the tibia required to visualize a flat ACL. The orientation of tibial and femoral footprint was described in a coronal plane for the tibia and a sagittal plane for the femur.

RESULTS

In the 42 knees that were finally included, the ACL was always displayed as a single ribbon-like structure. The torsion of the fibers was on average 83.6° (± 9.4°) in 90° knee flexion. The twisting could be explained by the different orientations of the femoral (vertical in a sagittal plane) and tibial (horizontal in a coronal plane) footprints. An intraligamentous proximal cleavage area was encountered in 11 cases (i.e., 26%).

CONCLUSIONS

The ACL is a twisted structure with 83.6° of external torsion of fibers in 90° knee flexion. It is the torsion in the fibers, due to the relative position of bone insertions, which gives the ACL the appearance of being double bundle.

CLINICAL RELEVANCE

The concept of the torsional flat structure of the native ACL may be of importance during ACL reconstruction, both in terms of graft choice (flat rather than cylindrical) and of technical positioning (torsion).

Graft Diameter as a Predictor for Revision Anterior Cruciate Ligament Reconstruction and KOOS and EQ-5D Values: A Cohort Study From the Swedish National Knee Ligament Register Based on 2240 Patients

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction (ACLR) using a hamstring tendon (HT) autograft is an effective and widespread method. Recent studies have identified a relationship between the graft diameter and revision ACLR.

PURPOSE

To evaluate the influence of the graft diameter on revision ACLR and patient-reported outcomes in patients undergoing primary ACLR using HT autografts.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A prospective cohort study was conducted using the Swedish National Knee Ligament Register (SNKLR) involving all patients undergoing primary ACLR using HT autografts. Patients with graft failure who needed revision surgery (cases) were compared with patients not undergoing revision surgery (controls). The control group was matched for sex, age, and graft fixation method in a 3:1 ratio. Conditional logistic regression was performed to produce odds ratios and 95% CIs. Univariate linear regression analyses were performed for patient-related outcomes. The Knee injury and Osteoarthritis Outcome Score (KOOS) and EuroQol 5 dimensions questionnaire (EQ-5D) values were obtained.

RESULTS

A total of 2240 patients were included in which there were 560 cases and 1680 controls. No significant differences between the cases and controls were found for sex (52.9% male), mean age (21.7 years), and femoral and tibial fixation. The mean graft diameter for the cases was 8.0 ± 0.74 mm and for the controls was 8.1 ± 0.76 mm. In the present cohort, the likelihood of revision surgery for every 0.5-mm increase in the HT autograft diameter between 7.0 and 10.0 mm was 0.86 (95% CI, 0.75-0.99; P = .03). Univariate linear regression analysis found no significant regression coefficient for the change in KOOS or EQ-5D values.

CONCLUSION

In a large cohort of patients after primary ACLR with HT autografts, an increase in the graft diameter between 7.0 and 10.0 mm resulted in a 0.86 times lower likelihood of revision surgery with every 0.5-mm increase. This study provides further evidence of the importance of the HT autograft size in intraoperative decision making.

Influence of change of tunnel axis angle on tunnel length during double-bundle ACL reconstruction via the transportal technique

BACKGROUND

Commercially available flexible reamer and curved guide systems allow a certain degree of control over intra-articular tunnel orientation, therefore allows a wide range of intra-osseous femoral tunnel orientations, contrary to the femoral tunneling technique using a straight guide pin, which are determined by knee flexion angle. We sought to find the clinical relevance of intra-osseous femoral tunnel orientations in the respect of tunnel length. To evaluate the relationship between the tunnel axis angle in three orthogonal planes and tunnel length in the anteromedial (AM) and posterolateral (PL) femoral tunnels in patients who underwent anatomic double-bundle anterior cruciate ligament reconstruction (DB-ACLR) using the transportal (TP) technique with a 42^o curved guide.

METHODS

A total of 40 patients who underwent primary DB-ACLR with the TP technique using a curved guide were evaluated retrospectively. The tunnel axis angle in three orthogonal planes were evaluated on a three-dimensional surface model constructed using an axial computed tomography scan obtained after reconstruction. Then, correlations with tunnel length were analyzed.

RESULTS

In the AM tunnel, tunnel axis angles in the coronal (β = 0.0252, p = 0.022) and sagittal (β = 0.0168, p = 0.029) plane showed significant correlations with tunnel length, while the axial plane did not (p = 0.493) (adjusted R² = 0.801). In the PL tunnel, only tunnel axis angles in the axial plane (β = 0.0262, p = 0.008) showed a significant relationship with tunnel length (adjusted R² = 0.700).

CONCLUSION

Drilling at a higher angle in the coronal and sagittal planes in AM tunnels and at a higher angle in the axial plane in PL tunnels decreases the incidence of short femoral tunnels.

The correlation of femoral tunnel length with the height and area of the lateral wall of the femoral intercondylar notch in anatomical single-bundle ACL reconstruction

PURPOSE

The purpose of this study was to reveal the correlation between femoral tunnel length and the height and area of the lateral wall of the femoral intercondylar notch in anatomical single-bundle anterior cruciate ligament (ACL) reconstruction .

METHODS

Twenty-four subjects undergoing anatomical single-bundle ACL reconstruction were included in this study (19 females and 5 males; average age 45.5 ± 16.7). In the anatomical single-bundle ACL reconstruction, the femoral and tibial tunnels were created close to the anteromedial bundle insertion site. Using post-operative three-dimensional computed tomography (3D-CT), an accurate lateral view of the femoral condyle was evaluated. The correlation of femoral tunnel length, which was measured intra-operatively, with the length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch was statistically analysed. Tunnel placement was also evaluated using 3D-CT (Quadrant method).

RESULTS

The average femoral tunnel length was 35.3 ± 4.9 mm. The length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch were 33.6 ± 3.4, 22.8 ± 2.4, and 734.6 ± 136 mm², respectively. Both the height and the area of the lateral wall of the femoral intercondylar notch were significantly correlated with femoral tunnel length. Femoral tunnel placement was 24.1 ± 3.9 % in a shallow-deep direction, and 33.5 ± 7.7 % in a high-low direction.

CONCLUSION

The height and area of the lateral wall of the femoral intercondylar notch are correlated with femoral tunnel length in anatomical single-bundle ACL reconstruction. For clinical relevance, surgeons should be careful not to make the femoral tunnel too short in knees in which the femoral intercondylar notch is low in height or small in size.

LEVEL OF EVIDENCE

Case-controlled study, Level III.

Length of the femoral tunnel in anatomic ACL reconstruction: comparison of three techniques

PURPOSE

The aim of this paper was to determine whether the change in the position of the patient's leg as well as the use of flexible reamers may help in obtaining a longer femoral tunnel with minimal risk of perforating the posterior cortex.

METHODS

One hundred and twenty-five patients who had undergone anatomic ACL reconstruction between 2010 and 2013 were included in this prospective cohort study. The first group was composed of patients whose femoral tunnel had been drilled with rigid reamers, while the leg being operated on was positioned on an arthroscopic leg holder (82 patients). In the second group of patients, the femoral tunnel was also drilled with rigid reamers, but the leg was positioned on the table (25 patients), while the third group was composed of patients whose femoral tunnel was drilled with flexible reamers, and the leg was positioned on a leg holder (18 patients). The length of the femoral tunnel was measured intraoperationally, while the site of femoral insertion and the position of the tunnel were read from native radiographic images.

RESULTS

When the femoral tunnel was drilled on the medial aspect of the lateral condyle, the centre of the tunnel was located at 31.4 % from the most proximal point of the femoral condyle and 34.7 % from the Blumensaat line. The length of the tunnel drilled with rigid reamers on the operating table (36.1 mm) was statistically significantly greater (p < 0.05) than the length of the tunnel drilled with the same reamers, but with the leg positioned on the leg holder (32.5 mm). The length of the tunnel drilled with flexible reamers with the leg positioned on the leg holder (42.5 mm) was highly statistically significantly greater than the length of the tunnel drilled with rigid reamers (p < 0.01), and it was statistically significantly greater than the length of the tunnel drilled with rigid reamers with the leg placed on the operating table (p < 0.05).

CONCLUSION

The drilling of the femoral tunnel during anatomic ACL reconstruction with the use of flexible reamers provides a longer femoral tunnel than when it is drilled with rigid reamers, without any danger of perforation of the posterior cortex.

LEVEL OF EVIDENCE

III.

Comparison of outcome after anatomic double-bundle and antero-medial portal non-anatomic single-bundle reconstruction in ACL-injured patients

PURPOSE

The aim of this study was to compare anatomic double-bundle anterior cruciate ligament reconstruction with non-anatomic single-bundle reconstruction.

METHODS

In a prospective consecutive series, 94 unselected patients [45 anatomic double-bundle (ADB) and 49 non-anatomic single-bundle (SB)] underwent ACL reconstruction involving hamstring tendon autograft, interference screw fixation on both the femoral and tibial side and drilling the femoral tunnel(s) through the antero-medial portal in both groups. In the ADB group, the remnants of the ACL were identified and the grafts were placed anatomically. In the SB group, traditional placement of the graft was performed in a less anatomic manner. Pre-operatively, the groups were comparable in terms of age, gender, time between injury and operation and associated injuries. One independent physiotherapist performed all the pre-operative and post-operative assessments.

RESULTS

The follow-up period was 26 (22-34) and 24 (23-30) months in the ADB and SB groups, respectively (p = 0.005). At follow-up, 78 % in the ADB group and 74 % in the SB group had a negative pivot-shift test (n.s.). The KT-1000 134N measurements were 2 (-5 to 10.5) and 2 (-4 to 7) mm in the ADB and SB groups, respectively (n.s.). At follow-up, the extension deficit was significantly larger in the ADB group than in the SB group (p = 0.001). The Tegner activity scale was significantly higher in the ADB group both pre-operatively and at follow-up (p = 0.03 and p = 0.004). In overall terms, both groups had improved significantly at the two-year follow-up.

CONCLUSION

In an unselected group of ACL-injured patients, anatomic double-bundle reconstruction did not result in better rotational or antero-posterior stability measurements than antero-medial portal non-anatomic single-bundle reconstruction at the two-year follow-up.

LEVEL OF EVIDENCE

III.

Osteogenic and tenogenic induction of hBMSCs by an integrated nanofibrous scaffold with chemical and structural mimicry of the bone–ligament connection

A novel electrospinning nanofiber collecting device was designed and utilized to fabricate an integrated PCL nanofibrous scaffold with a “random–aligned–random” structure.

Primary Anterior Cruciate Ligament Reconstruction. How Do We Do It?

Anterior cruciate ligament (ACL) tears are frequently seen in current practice mostly affecting the young, active subjects, and usually require ligament reconstruction in order to restore normal knee kinematics. As worldwide interest in anatomic reconstruction grew over the last decade, we have also refined our technique in order to restore the anatomical function as near to the normal as possible. This anatomical restoration concept is believed to prevent the onset of osteoarthritis, which the non-anatomic reconstructions fail to attain. The knowledge gained from the ACL anatomy, function and kinematics has helped in developing the current anatomic methods of reconstruction, which take into account patient anatomy, the rupture pattern, as well as the comorbidities. We present our approach to anatomical single- and double-bundle ACL reconstruction.

Is There a Difference in Graft Motion for Bone-Tendon-Bone and Hamstring Autograft ACL Reconstruction at 6 Weeks and 1 Year?

BACKGROUND

Bone-patellar tendon-bone (BTB) grafts are generally believed to heal more quickly than soft tissue grafts after anterior cruciate ligament (ACL) reconstruction, but little is known about the time course of healing or motion of the grafts within the bone tunnels.

HYPOTHESIS

Graft-tunnel motion will be greater in hamstring (HS) grafts compared with BTB grafts and will be less at 1 year than at 6 weeks.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve patients underwent anatomic single-bundle ACL reconstruction using HS or BTB autografts (6 per group) with six 0.8-mm tantalum beads embedded in each graft. Dynamic stereo x-ray images were collected at 6 weeks and 1 year during treadmill walking and stair descent and at 1 year during treadmill running. Tibiofemoral kinematics and bead positions were evaluated. Graft-tunnel motion was based on bead range of motion during the loading response phase (first 10%) of the gait cycle.

RESULTS

During treadmill walking, there was no difference in femoral tunnel or tibial tunnel motion between BTB or HS grafts at 6 weeks (BTB vs HS: 2.00 ± 1.05 vs 1.25 ± 0.67 mm [femoral tunnel]; 1.20 ± 0.63 vs 1.27 ± 0.71 mm [tibial tunnel]), or 1 year (BTB vs HS: 1.62 ± 0.76 vs 1.08 ± 0.26 mm [femoral tunnel]; 1.58 ± 0.75 vs 1.68 ± 0.53 mm [tibial tunnel]). During stair descent, there was no difference in femoral or tibial tunnel motion between BTB and HS grafts at 6 weeks or 1 year. With running, there was no difference between graft types at 1 year. For all results, P values were > .05. Knee kinematics were consistent with the literature.

CONCLUSION

During walking and stair descent, ACL reconstruction using suspensory fixation yielded no difference between graft types in femoral or tibial tunnel motion at 6 weeks or 1 year. All subjects were asymptomatic with knee kinematics similar to that of the literature. The significance of persistent, small (1 to 3 mm) movements at 1 year for healing or graft performance is unknown.

CLINICAL RELEVANCE

These study results may have significant implications for graft choice, rehabilitation strategies, and timing for return to sports.

Combined Intra-articular and Extra-articular Reconstruction in Anterior Cruciate Ligament-Deficient Knee: 25 Years Later

PURPOSE

To determine whether an anterior cruciate ligament (ACL)-reconstructed knee with hamstring autograft has a greater incidence of degenerative changes when an extra-articular reconstruction is added and to determine the effect of the combined reconstruction on knee stability and function at long-term follow-up.

METHODS

For this retrospective study, patients who underwent ACL reconstruction between January 2002 and December 2003 were selected and classified into 2 groups, I and II. Group I consisted of patients operated by a standard ACL reconstruction, and group II consisted of patients in whom, owing to the presence of risk factors (severe pivot shift graded +++ or high-risk sports), an extra-articular reconstruction performed with ileo-tibial tract according to McIntosh as modified by Cocker Arnold technique, was used in conjunction with intra-articular ACL reconstruction. At final follow-up, Lysholm, International Knee Documentation Committee (IKDC), and Tegner scores were used. An arthrometric KT-1000 evaluation was done. Comparative weight-bearing radiographs were taken, including a skyline view for the patellofemoral joint and analyzed according to Fairbank, Kellgren, and IKDC classification.

RESULTS

Seventy-two of the 75 (96%) patients in group I and 68 of the 75 patients in group II were available at the final follow-up (minimum 10 years). Subjective scores improved significantly in both groups, with no significant difference. Objectively, the number of patients receiving C and D IKDC objective activity scores in group I (7/56; 12.5%) was significantly higher than in group II (0/60) (P = .01). Considering as a failure a side-to-side arthrometric difference more than 5 mm or a pivot shift test graded as ++ or +++, or any giving way episode occurring postoperatively, we found 8 cases in group I and no cases in group II (P = .01) despite the presence of risk factors that group I did not include. Radiologic evaluation showed less arthritic changes in group II in both tibiofemoral and patellofemoral joints.

CONCLUSIONS

On the basis of the results of this study, adding an extra-articular reconstruction to an anatomically placed intra-articular ACL reconstruction, followed by a modern rehabilitation protocol, does not increase the risk of osteoarthritis and may be able to reduce the rate of failure.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction With a Free Quadriceps Tendon Autograft

Anatomic double-bundle anterior cruciate ligament (ACL) reconstruction aims to restore the 2 functional bundles of the ACL in an attempt to better reproduce the native biomechanics of the injured knee and promote long-term knee health. However, this concept is not fully accepted and is not performed on a standard basis. In addition, the superiority of this technique over the conventional single-bundle technique has been questioned, especially the long-term clinical results. One of the down sides of the double-bundle reconstruction is the complexity of the procedure, with increased risks, operative time, and costs compared with the single-bundle procedure. Also, the revision procedure, if necessary, is more challenging. We propose a technique that has some advantages over the traditional double-bundle procedure, using a single femoral tunnel, 2 tibial tunnels, and a free quadriceps tendon autograft.

Single-bundle versus double-bundle anterior cruciate ligament reconstruction: A comparative study with propensity score matching

BACKGROUND

Numerous studies have elucidated the functional anatomy and biomechanics of the anterior cruciate ligament (ACL), as a result, double-bundle (DB) ACL reconstruction has received much attention and has become a popular choice because it gives better rotational stability. Many other studies, however, found no differences with respect to stability, and/or other clinical outcomes between the DB and single-bundle (SB) techniques. There is still not enough evidence as to whether the anatomical DB anterior cruciate ligament reconstruction (ACLR) is superior to anatomical SB reconstruction. The purpose of this study is to compare various clinical and functional outcomes between SB and DBACLR at 2 years followup.

MATERIALS AND METHODS

Medical records of patients with ACLR available for at least 2 years followup were reviewed retrospectively. 191 patients (164 males and 25 females) for SB and 48 patients (40 males and 8 females) for DB were selected using the inclusion and exclusion criteria. The mean age of SB and DB was 29.9 and 24.8 years, respectively. Propensity score (PS) was calculated based on age, sex and Tegner activity score and 48 patients in each group were matched by the PS. Lysholm score, International Knee Documentation Committee (IKDC) subjective knee score and Tegneractivity score were investigated. Functional performance tests, isokinetic muscle strength test with Biodex system, pivot shift test and KT-2000 arthrometer test were performed.

RESULTS

At 2 years followup, there were no significant differences between SB and DB group in Lysholm score (92.9 vs. 90.6, P = 0.224), IKDC subjective knee score (88.7 vs. 87.0, P = 0.524), Tegner activity score (7.3 vs. 8.0, P = 0.059). No significant differences were also found in all functional performance tests, isokinetic muscle strength tests in 60° and 180°/s, KT-2000 arthrometer test and pivot shift test (P > 0.05).

CONCLUSIONS

There were no significant differences of clinical and functional outcomes between SB and DB ACLR at 2 years followup.

Blumensaat's line is not always straight: morphological variations of the lateral wall of the femoral intercondylar notch

PURPOSE

The purpose of this study was to evaluate the morphological variations of the lateral wall of the femoral intercondylar notch.

METHODS

Fifty-two non-paired human cadaver knees were used. All soft tissues around the knee were resected except the ACL. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch parallel to the plane of the femoral bone shaft. The ACL was carefully dissected, and the periphery of the ACL insertion site was outlined on the femoral side. An accurate lateral view of the femoral condyle was photographed with a digital camera, and the images were downloaded to a personal computer. The morphological variations of Blumensaat's line, the height and area of the lateral wall of the femoral intercondylar notch and the size of the femoral ACL footprints were measured with Image J software.

RESULTS

Blumensaat's line exhibited three types of morphological variations. A straight line was observed in 19 knees (37 %) (straight type). A protrusion spanning less than half of the line was observed at the proximal part of Blumensaat's line in 10 knees (19 %) (small hill type). A protrusion spanning more than half of the line was observed at the proximal part of the line in 23 knees (44 %) (large hill type). In some knees with this large hill type variation, the appearance was similar to that of anterior spur. No significant differences between these three types were observed in either the height and area of the lateral wall of the femoral intercondylar notch or the area of the femoral ACL footprint.

CONCLUSION

In conclusion, Blumensaat's line has three types of morphological variations (straight, small hill and large hill types). For the clinical relevance, when ACL surgery is performed in knees with small or large hill type variations, surgeons should pay close attention to femoral tunnel evaluation and placement, especially for the use of Quadrant method. The grid placement of Quadrant method would be changed in the knees of these type variations.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

III.

Surgical Adjustment of the Guide Pin to Perform a Correct Tibial Tunnel in Anatomical Anterior Cruciate Ligament Single-Bundle Reconstruction

Anatomical positioning of the graft in anterior cruciate ligament reconstruction is important to restore normal knee kinematics and prevent early joint degeneration. Inadequate position of a first attempt to place the guide pin within the center of the tibial footprint may occur. Therefore, its adjustment is important to achieve the anatomical positioning of the graft within the tibial footprint. When the guide pin exits eccentrically in an inadequate position, it is possible to correct it to the center of the footprint. A small tunnel with a 4.5-mm reamer is made and the guide pin is shifted to the center of the footprint. The center of the tunnel can be corrected until 50% and in all direction in relation to the initial drilled tunnel, without additional associated morbidity. Once the correct position of the center is achieved, the guide pin is fixed in the femoral notch roof to guarantee the accurate correction of the axis, without toggling of the guide pin inside the tunnel and metal dusting. The final tunnel is then drilled with the same size of the graft. With this technique it is possible to adjust an eccentrically misplaced guide pin to the center of the footprint without additional morbidity.

Effects of Remnant Tissue Preservation on the Tendon Graft in Anterior Cruciate Ligament Reconstruction: A Biomechanical and Histological Study

BACKGROUND

There is controversy regarding the efficacy of remnant tissue preservation on graft healing in anterior cruciate ligament (ACL) reconstruction.

HYPOTHESIS

The preserved remnant tissue will (1) adhere to the graft surface and undergo a remodeling process, (2) accelerate graft revascularization, (3) increase the number of graft mechanoreceptors by 4 weeks, and (4) improve anteroposterior knee laxity and structural properties of the graft by 12 weeks.

STUDY DESIGN

Controlled laboratory study.

METHODS

Forty-two sheep were randomly divided into 2 groups of 21 animals. In group I, the ACL was completely removed. In group II, the ACL was transected at the midsubstance but not debrided. ACL reconstruction was performed using a semitendinosus tendon autograft in both groups. Histological changes of the grafted tendon and the remnant tissue were evaluated at 4 and 12 weeks after surgery. Biomechanically, anterior translation and knee joint stiffness under an anterior drawer force and the structural properties of the femur-graft-tibia complex were evaluated.

RESULTS

The preserved remnant tissue was histologically distinct from the graft at 4 weeks, while the tissue partially adhered to the graft surface at 12 weeks. The ACL remnant tissue significantly accelerated revascularization in the grafted tendon at 4 weeks and significantly increased the number of mechanoreceptors at 4 and 12 weeks. In addition, remnant preservation significantly improved anterior translation (9.3 ± 2.1 mm and 5.4 ± 1.7 mm at 60° of knee flexion in groups I and II, respectively) and knee joint stiffness at 12 weeks. However, there were no significant differences in the structural properties between the 2 groups at 4 and 12 weeks after surgery.

CONCLUSION

Preservation of the ACL remnant tissue in ACL reconstruction enhanced cell proliferation, revascularization, and regeneration of proprioceptive organs in the reconstructed ACL and reduced anterior translation. However, remnant preservation did not improve the structural properties of the graft.

CLINICAL RELEVANCE

These results imply that preservation of the ACL remnant tissue may improve graft healing after ACL reconstruction.

Comparison of Anatomic Double- and Single-Bundle Techniques for Anterior Cruciate Ligament Reconstruction Using Hamstring Tendon Autografts: A Prospective Randomized Study With 5-Year Clinical and Radiographic Follow-up

BACKGROUND

The aim of this prospective randomized study was to compare the outcomes of the anatomic double-bundle (DB) and anatomic single-bundle (SB) techniques 5 years after anterior cruciate ligament (ACL) reconstruction. Since more effective restoration of rotational laxity is considered the main advantage of the DB technique, the pivot-shift test was the primary outcome variable of the study.

HYPOTHESIS

Double-bundle ACL reconstruction will result in a better outcome in terms of the pivot-shift test.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 105 patients (33 women, 72 men; median age, 27 years; range, 18-52 years) were randomized and underwent ACL reconstruction (DB group, n = 53; SB group, n = 52). All reconstructions were performed anatomically by identifying the ACL footprints, using the anteromedial portal for the femoral tunnel drilling, and utilizing interference screw for tibial and femoral fixation. A single blinded observer examined the patients preoperatively and at follow-up (median, 64 months; range, 55-75 months). Multiple subjective and objective clinical evaluation tests and radiographic assessments of osteoarthritis (OA) were performed using the Ahlbäck, Kellgren-Lawrence, and Fairbank grading systems at 6 weeks postoperatively and at the final follow-up evaluation.

RESULTS

Preoperatively, no differences were found between the study groups, apart from the preinjury Tegner activity level, which was lower in the DB group (SB: mean, 7.8 [range, 3-9]; DB: mean, 7.3 [range, 0-9]; P = .02). Eighty-seven patients (83%) were available for examination at the 5-year follow-up. Statistical differences could not be found between the groups in terms of the pivot-shift test, KT-1000 arthrometer laxity measurements, manual Lachman test, single-legged-hop test, square-hop test, range of motion, Lysholm knee scoring scale, Tegner activity scale, or Knee injury and Osteoarthritis Outcome Score. Correspondingly, no differences were found between the groups regarding the presence of OA at follow-up. However, a significant increase of OA was found within the DB group at the 5-year follow-up. Both groups improved at follow-up compared with the preoperative assessment in terms of the laxity tests, hop tests, and scoring scales.

CONCLUSION

At the 5-year follow-up of an unselected group of patients, anatomic DB reconstruction was not superior to anatomic SB reconstruction in terms of the pivot-shift test.

The difference in centre position in the ACL femoral footprint inclusive and exclusive of the fan-like extension fibres

PURPOSE

The purpose of this study was to compare the centre position of each anterior cruciate ligament bundle in its femoral footprint in measurements including and excluding the fan-like extension fibres.

METHODS

Fourteen non-paired human cadaver knees were used. All soft tissues around the knee were resected except the ligaments. The ACL was divided into antero-medial (AM) and postero-lateral (PL) bundles according to the difference in tension patterns. The ACL was carefully dissected, and two outlines were made of the periphery of each bundle insertion site: those which included and those which excluded the fan-like extension fibres. An accurate lateral view of the femoral condyle was photographed with a digital camera, and the images were downloaded to a personal computer. The centre position of each bundle, including and excluding the fan-like extension fibres, was measured with ImageJ software (National Institution of Health). Evaluation of the centre position was performed using the modified quadrant method.

RESULTS

The centre of the femoral AM bundle including the fan-like extension was located at 28.8% in a shallow-deep direction and 37.2% in a high-low direction. When the AM bundle was evaluated without the fan-like extension, the centre was significantly different at 34.6% in a shallow-deep direction (p = 0.000) and 36% in a high-low direction. The centre of the PL bundle including the fan-like extension was found at 37.1% in a shallow-deep direction and 73.4% in a high-low direction. When the PL bundle was evaluated without the fan-like extension, the centre was significantly different at 42.7% in a shallow-deep direction (p = 0.000) and 69.3% in a high-low direction (p = 0.000).

CONCLUSION

The centre position of the AM and PL bundles in the femoral ACL footprint was significantly different depending on the inclusion or exclusion of the fan-like extension fibres. For the clinical relevance, to reproduce the direct femoral insertion in the anatomical ACL reconstruction, tunnels should be placed relatively shallow and high in the femoral ACL footprint.

Proportional evaluation of anterior cruciate ligament footprint size and knee bony morphology

PURPOSE

The purpose of this study was to reveal the correlation in size between the native anterior cruciate ligament (ACL) footprint and the femoral intercondylar notch and the tibia plateau, and to calculate the proportion in size between the ACL footprint and knee bony morphology.

METHODS

Twenty-six non-paired human cadaver knees were used. All soft tissues around the knee were resected except the ACL. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch. The ACL was carefully dissected, and the periphery of the ACL insertion site was outlined on both the femoral and tibial sides. An accurate lateral view of the femoral condyle and an axial view of the tibial plateau were photographed with a digital camera, and the images were downloaded to a personal computer. The size of the femoral and tibial ACL footprints and the area of the lateral wall of the intercondylar notch and the tibia plateau were measured with Image J software (National Institution of Health).

RESULTS

The sizes of the native femoral and tibial ACL footprints were 69.8 ± 25 and 133.8 ± 31.3 mm(2), respectively. The areas of the lateral wall of the intercondylar notch and the tibia plateau were 390.5 ± 70.5 and 2,281.7 ± 377.3 mm(2), respectively. The femoral ACL footprint area and the area of the lateral wall of the femoral intercondylar notch (Pearson's correlation coefficient = 0.603, p = 0.001), and the tibial ACL footprint area and the area of the tibia plateau (Pearson's correlation coefficient = 0.452, p = 0.02) both showed significant correlation. The femoral ACL footprint was 17.8 ± 4.9 %, the size of the lateral wall of the femoral intercondylar notch, and the tibial ACL footprint was 5.9 ± 1.3 %, the size of the tibia plateau.

CONCLUSION

For clinical relevance, the femoral ACL footprint is approximately 18 %, the size of the intercondylar notch, and the tibial ACL footprint is approximately 6 %, the size of the tibia plateau. It might be possible to predict the size of the ACL measuring these parameters preoperatively.

Reconstruction of the anterior cruciate ligament by means of an anteromedial portal and femoral fixation using Rigidfix

Objective

To evaluate a series of patients who underwent surgery for reconstruction of the anterior cruciate ligament with flexor tendons, by means of the anteromedial transportal technique using Rigidfix for femoral fixation, and to analyze the positioning of the pins by means of tomography.

Methods

Thirty-two patients were included in the study. The clinical evaluation was done using the Lysholm, subjective IKDC and Rolimeter. All of them underwent computed tomography with 3D reconstruction in order to evaluate the entry point and positioning of the Rigidfix pins in relation to the joint cartilage of the lateral condyle of the femur.

Results

The mean Lysholm score obtained was 87.81 and the subjective IKDC was 83.72. Among the 32 patients evaluated, 43% returned to activities that were considered to be very vigorous, 9% vigorous, 37.5% moderate and 12.5% light. In 16 patients (50%), the distal entry point of the Rigidfix pin was located outside of the cartilage (extracartilage); in seven (21.87%), the distal pin injured the joint cartilage (intracartilage); and in nine (28.12%), it was at the border of the lateral condyle of the femur.

Conclusion

The patients who underwent ACL reconstruction by means of the anteromedial transportal using the Rigidfix system presented satisfactory clinical results over the length of follow-up evaluated. However, the risk of lesions of the joint cartilage from the distal Rigidfix pin needs to be taken into consideration when the technique via an anteromedial portal is used. Further studies with larger numbers of patients and longer follow-up times should be conducted for better evaluation.

High Axial Loads While Walking Increase Anterior Tibial Translation in Intact and Anterior Cruciate Ligament-Deficient Knees

PURPOSE

To evaluate the effect of high axial loading (AL) on anterior tibial translation (ATT) according to the increase in knee flexion and the effect of valgus stress (VS) and internal rotation (IR) combined with high AL in intact and anterior cruciate ligament (ACL)-deficient knees according to the increase in knee flexion.

METHODS

We used 10 fresh-frozen, human cadaveric knees. Different loading conditions (134-N anterior drawer, 1,000-N AL, 10-Nm VS, and 5-Nm IR) were sequentially combined, and ATT was measured at 0°, 15°, 30°, 45°, and 60° of flexion in the intact and ACL-deficient knees.

RESULTS

ATT increased significantly by adding high AL in intact knees (P = .001) and ACL-deficient knees (P < .0001) according to the change in flexion angle (P < .0001). Under high AL, ATT in the ACL-deficient knees was significantly larger than that in the intact knees for all loading conditions, and it also increased gradually according to the increase in knee flexion (P = .0001). ATT increased significantly after adding IR or VS with high AL in intact knees (VS, P = .002; VS/IR, P = .03) and ACL-deficient knees (VS, P = .0004) at some of the flexion angles.

CONCLUSIONS

The added high AL increased ATT in intact and ACL-deficient knees from 0° to 60° of flexion. The effect of high AL on ATT became greater in ACL-deficient knees than in intact knees, and ATT also gradually increased according to the increase in knee flexion from 0° to 60°. In both the intact and ACL-deficient knees, ATT increased significantly after valgus stress or IR from 0° to 60°.

CLINICAL RELEVANCE

ATT during weight bearing increases stress to the ACL, which worsens with valgus stress and/or IR forces. This finding should be considered when one is studying ACL injury mechanisms, as well as prescribing rehabilitation after ACL surgery.

Dynamic Effect of Quadriceps Muscle Activation on Anterior Tibial Translation After Single-Bundle and Double-Bundle Anterior Cruciate Ligament Reconstruction

PURPOSE

To examine differences in anterior tibial translation in 3 groups: single-bundle anterior cruciate ligament (ACL)-reconstructed, double-bundle ACL-reconstructed, and ACL-intact knees under gradual dynamic quadriceps muscle activation.

METHODS

Thirty male patients underwent successful single-bundle (n = 15) and double-bundle (n = 15) ACL reconstructions; 15 healthy controls were included in the study. Anterior tibial translation was assessed at 30° of knee flexion in the resting position (0% quadriceps activation) and under 50% and 100% of maximum quadriceps concentric contraction using an isokinetic dynamometer with the KT-2000 arthrometer securely attached to the participants' knees.

RESULTS

The 2 ACL-reconstructed groups were similar regarding International Knee Documentation Committee (IKDC), Knee Injury and Osteoarthritis Score (KOOS), Tegner, and Lysholm scores and preliminary isokinetic evaluation (P = .38). Quadriceps activation significantly affected anterior tibial translation (P = .001, α = 0.98). In all 3 study groups, anterior tibial translation was significantly higher under 100% quadriceps activation compared with 0% contraction (P = .01) and 50% quadriceps activation (P = .047). There were no between-group differences in anterior tibial translation with 0%, 50%, or 100% quadriceps activation (P = .46).

CONCLUSIONS

Under quadriceps muscle activation, anteroposterior knee laxity in ACL-intact and ACL-reconstructed knees is gradually increased. Single-bundle and double-bundle ACL-reconstructed knees show a similar increase in anterior tibial translation under gradual quadriceps contraction. When comparing different ACL reconstruction techniques in the experimental setting, dynamic, in addition to static, testing is advised to reach a comprehensive assessment of anteroposterior knee stability.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

Level IV, case series.

Size correlation between the tibial anterior cruciate ligament footprint and the tibia plateau

PURPOSE

The purpose of this study was to reveal the correlation between the size of the native anterior cruciate ligament (ACL) footprint and the size of the tibia plateau.

METHODS

Twenty-four non-paired human cadaver knees were used. All soft tissues around the knee were resected except the ACL. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch. The ACL was carefully dissected, and the periphery of the ACL insertion site was outlined on both the femoral and tibial sides. An accurate lateral view of the femoral condyle and the tibial plateau was photographed with a digital camera, and the images were downloaded to a personal computer. The size of the femoral and tibial ACL footprints, and anterior-posterior (AP) and medial-lateral (ML), lengths of the tibia plateau and area of tibia plateau were measured with Image J software (National Institution of Health).

RESULTS

The sizes of the native femoral and tibial ACL footprints were 72.3 ± 24.4 and 134.1 ± 32.4 mm(2), respectively. The AP lengths of the whole, medial and lateral facet of the tibia plateau were as follows: 44.5 ± 4.1, 40.8 ± 4.1 and 36.8 ± 4 mm, respectively. The ML length of the tibia plateau was 68.3 ± 5.5 mm. Total area of tibia plateau was 2,282.9 ± 378.7 mm(2). The AP length of the lateral facet of the tibia plateau (Pearson's correlation coefficient = 0.508, p = 0.011) and the total area of tibia plateau (Pearson's correlation coefficient = 0.442, p = 0.031) were significantly correlated with the size of the tibial ACL footprint.

CONCLUSION

For clinical relevance, the AP length of lateral facet of the tibia plateau and total area of tibia plateau are significantly correlated with the size of the tibial ACL footprint. It might be possible to predict the size of the ACL measuring these parameters.

Anatomic anterior cruciate ligament reconstruction: a changing paradigm

Injury to the anterior cruciate ligament (ACL) of the knee is potentially devastating for the patient and can result in both acute and long-term clinical problems. Consequently, the ACL has always been and continues to be of great interest to orthopaedic scientists and clinicians worldwide. Major advancements in ACL surgery have been made in the past few years. ACL reconstruction has shifted from an open to arthroscopic procedure, in which a two- and later one-incision technique was applied. Studies have found that traditional, transtibial arthroscopic single-bundle reconstruction does not fully restore rotational stability of the knee joint, and as such, a more anatomic approach to ACL reconstruction has emerged. The goal of anatomic ACL reconstruction is to replicate the knee's normal anatomy and restore its normal kinematics, all while protecting long-term knee health. This manuscript describes the research that has changed the paradigm of ACL reconstruction from traditional techniques to present day anatomic and individualized concepts.

Three-dimensional computed tomography evaluation of anterior cruciate ligament footprint for anatomic single-bundle reconstruction

PURPOSE

Femoral and tibial footprint coordinates have been well studied in double-bundle anterior cruciate ligament (ACL) reconstruction. However, in a single-bundle reconstruction approach, the central coordinate of femoral and tibial footprints have not been determined. The purpose of this study was to describe the central point locations of the ACL footprints visualized by three-dimensional computed tomography (3D CT) images and analysed by the quadrant method.

METHODS

Eight cadaveric knees were dissected, and the central points of ACL femoral and tibial footprints were marked and analysed using 3D CT images.

RESULTS

In the present study, the means (and standard deviation) of ACL femoral footprint dimensions were in the ventral-dorsal plane and in the cranial-caudal plane 9.4 ± 0.8 and 15.6 ± 0.9 mm, respectively. In the tibial side, the means of ACL footprint dimensions were in the anterior-posterior and in the medial-lateral 18.5 ± 1.9 and 15.5 ± 1.0 mm, respectively. In the tomographic analyses, the means of femoral central location coordinates in the ventral-dorsal (y) and in the cranial-caudal (x) axes were 35.3 ± 4.5 and 30.0 ± 1.6 %, respectively. The means of tibial central location coordinates were in the anterior-posterior (y) and in the medial-lateral (x) axes, respectively: 40.5 ± 5.3 and 50.2 ± 1.3 %, respectively.

CONCLUSIONS

These computed tomographic coordinates might help future studies as a reference on ACL single-bundle anatomic reconstruction, with respect to the management of ACL revision surgery or in symptomatic patients after ACL reconstruction. Improvements in three-dimensional image acquisition could facilitate its intraoperative applicability in the coming years.

Regional fibrocartilage variations in human anterior cruciate ligament tibial insertion: a histological three-dimensional reconstruction

PURPOSE

We studied anterior cruciate ligament (ACL) tibial insertion architecture in humans and investigated regional differences that could suggest unequal force transmission from ligament to bone.

MATERIALS AND METHODS

ACL tibial insertions were processed histologically. With Photoshop software, digital images taken from the histological slides were collaged, contour lines were drawn, and different gray values were filled based on the structure. The data were exported to Amira software for three-dimensional reconstruction.

RESULTS

The uncalcified fibrocartilage (UF) layer was divided into three regions: lateral, medial and posterior according to the architecture. The UF zone was significantly thicker laterally than medially or posteriorly (p < 0.05). Similarly, the calcified fibrocartilage (CF) thickness was significantly greater in the lateral part of the enthesis compared to the medial and posterior parts (p < 0.05).

CONCLUSIONS

The UF quantity (more UF laterally) corresponding to the CF quantity (more CF laterally) at the ACL tibial insertion provides further evidence suggesting that the load transferred from the ACL to the tibia was greater laterally than medially and posteriorly.

Ribbon like appearance of the midsubstance fibres of the anterior cruciate ligament close to its femoral insertion site: a cadaveric study including 111 knees

PURPOSE

Recently, the configuration of the anterior cruciate ligament (ACL) from its direct femoral insertion to midsubstance was found to be flat. This might have an important impact for anatomical ACL reconstruction. The purpose of this anatomical study was to evaluate the macroscopic appearance of the ACL from femoral to midsubstance.

METHODS

The ACL was dissected in 111 human fresh frozen cadaver knees from its femoral insertion to midsubstance, and the shape was described. The anatomical findings were documented on digital photographs and on video. Thirty knees were sent for computed tomography (CT), magnetic resonance imaging (MRI) and histology of the femoral ACL insertion.

RESULTS

Two millimetres from its direct femoral insertion, the ACL fibres formed a flat ribbon in all dissected knees without a clear separation between AM and PL bundles. The ribbon was in exact continuity of the posterior femoral cortex. The width of the ribbon was between 11.43 and 16.18 mm and the thickness of the ACL was only 2.54-3.38 mm. 3D CT, MRI and the histological examination confirmed above findings.

CONCLUSION

This is a detailed anatomical study describing the ribbon-like structure of the ACL from its femoral insertion to midsubstance. A key point was to carefully remove the surface fibrous membrane of the ACL. A total of 2-3 mm from its bony femoral insertion, the ACL formed a flat ribbon without a clear separation between AM and PL bundles. The ribbon was in exact continuity of the posterior femoral cortex. The findings of a flat ligament may change the future approach to femoral ACL footprint and midsubstance ACL reconstruction and to graft selection.

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.

Effect of femoral tunnel position on graft tension curves and knee stability in anatomic double-bundle anterior cruciate ligament reconstruction

PURPOSE

To evaluate the effect of the femoral tunnel position of the anteromedial bundle (AMB) and the posterolateral bundle (PLB) on the graft tension curves and knee stability in anatomic double-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

Forty-five patients who underwent anatomic double-bundle ACL reconstruction were included. AMB and PLB were provisionally fixed to a graft tensioning system in the following settings during surgery: (1) AMB at 20° and PLB at 0° (A20P0), (2) AMB at 20° and PLB at 20° (A20P20), and (3) AMB at 20° and PLB at 45° (A20P45). Bundle tension was recorded during knee flexion-extension. A pivot shift test was also evaluated. Femoral tunnel positions of the AMB and PLB were then assessed by three-dimensional computed tomography, and the correlation between femoral tunnel position and tension change pattern or residual pivot shift was evaluated.

RESULTS

The depth of the PLB tunnel position was correlated with the extent of tension reduction in the PLB between 0° and 30° irrespective of graft fixation settings, while neither the AMB tunnel position nor the height of the PLB tunnel position affected the tension change pattern. Ten cases showed grade 1 pivot shift only in the A20P0 setting. The PLB tunnel position in the pivot shift-positive cases was significantly deeper than that in the pivot shift-negative cases (27.5 ± 6.2 and 34.1 ± 5.5%, respectively, P = 0.002).

CONCLUSIONS

In anatomic double-bundle reconstruction, deeper PLB tunnel position was correlated with the larger tension reduction in the PLB between 0° and 30°. Fixation of the AMB at 20° and the PLB at 0° resulted in residual pivot shift phenomenon in 10/45 cases, and the PLB tunnel position in the pivot shift-positive cases was significantly deeper than that in the pivot shift-negative cases. In anatomic double-bundle reconstruction, the placement of PLB femoral tunnel must not be too deep, as it might lead to significant tension reduction in the PLB near extension and thus insufficient tension in the PLB, resulting in residual pivot shift phenomenon.

LEVEL OF EVIDENCE

IV.

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.

Three-dimensional analysis of bone tunnel changes after anatomic double-bundle anterior cruciate ligament reconstruction using multidetector-row computed tomography

BACKGROUND

The femoral and tibial bone tunnel enlargement after anatomic double-bundle anterior cruciate ligament reconstruction (ACL-R) has not been fully documented.

PURPOSE

To evaluate the region-specific bone tunnel volume changes and those transpositions using 3-dimensional multidetector-row computed tomography (MDCT) after anatomic double-bundle ACL-R.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Eleven patients who underwent unilateral double-bundle ACL-R with hamstring tendon autografts were included in this study. MDCT scanning of their knees was performed at 3 weeks and 1 year after surgery. The bone tunnel regions were extracted from the MDCT images, and the longitudinal axis of each bone tunnel was divided into 3 equal sections. The centroids of the outside and the articular thirds were then extracted from the bone tunnel position. Changes in the bone tunnel volume and the transposition of the articular third were calculated and compared.

RESULTS

At 1 year postoperatively, as compared with the 3-week postoperative value (set at 100%), the femoral bone tunnel volume of the anteromedial bundle (AMB) and posterolateral bundle (PLB) changed to 77.4% ± 15.3% and 102.3% ± 19.2% in the outside third and 122.3% ± 31.8% and 112.5% ± 34.4% in the articular third, respectively. The tibial bone tunnel volume of the AMB and the PLB changed to 108.6% ± 28.7% and 105.4% ± 22.6% in the tibial articular third and 54.9% ± 25.8% and 52.5% ± 26.9% in the outside third, respectively. The femoral outside third of the AMB and the tibial outside third of both the AMB and PLB were significantly reduced in bone tunnel volume. The centroid of the femoral articular third of the AMB moved 13°, 1.1 ± 0.6 mm posterodistally, and that of the PLB moved 35°, 0.8 ± 0.4 mm anterodistally. Furthermore, the centroid of the tibial articular third of the AMB moved 14°, 2.0 ± 1.6 mm posterolaterally, and that of the PLB moved 72°, 1.0 ± 1.3 mm posterolaterally.

CONCLUSION

Compared with 3 weeks postoperatively, the articular side outlets of the femoral and tibial bone tunnels at 1 year postoperatively had enlarged slightly but statistically maintained their volume, and they had moved a little in the direction that the grafts were pulled.

Commonly used ACL autograft areas do not correlate with the size of the ACL footprint or the femoral condyle

PURPOSE

The purpose of this study was to reveal the correlation between the size of the native anterior cruciate ligament (ACL) footprint and the area of commonly used autografts using cadaveric knees.

METHODS

Twenty-Four non-paired human cadaver knees were used. The size of the femoral and tibial ACL footprints, length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch were photographed and measured with Image J software (National Institution of Health). Simulating an semitendinosus tendon (ST) graft, the ST was cut in half. The bigger half was regarded as the antero-medial (AM) bundle, and the remaining half was regarded as the postero-lateral (PL) bundle. Simulating an semitendinosus and gracilis (ST-G) graft, the bigger half of the ST and G was regarded as the AM bundle, and the smaller half of the ST was regarded as the PL bundle. Each graft diameter was measured, and the graft area was calculated. Simulating a bone-patella tendon-bone (BPTB) graft, a 10-mm wide BPTB graft was harvested and the area calculated.

RESULTS

The sizes of the native femoral and tibial ACL footprints were 72.3 ± 24.4 and 134.1 ± 32.4 mm(2), respectively. The length of Blumensaat's line, and the height and area of the lateral wall of the femoral intercondylar notch were 29.5 ± 2.5 mm, 17.7 ± 2.3 mm, and 400.9 ± 62.6 mm(2), respectively. The average areas of the ST, ST-G, and BPTB graft were 52.7 ± 6.3, 64.7 ± 7.6, and 37.1 ± 7.5 mm(2). Both the height and the area of the lateral wall of the femoral intercondylar notch were significantly correlated with the femoral size of the ACL footprint (p = 0.007 and 0.008, respectively). However, no significant correlation was observed between ACL footprint size and autograft size. No significant correlation was observed between autograft size and the size of the lateral wall of the femoral intercondylar notch.

CONCLUSION

In ACL reconstruction, if the reconstructed ACL size is determined by the harvested autograft size alone, native ACL size and anatomy are unlikely to be reproduced.

Operative treatment of primary anterior cruciate ligament rupture in adults

Operative management of an acute anterior cruciate ligament (ACL) rupture may be required in young and active patients to stabilize the knee and return patients to desired daily activities. ACL reconstruction should be performed anatomically. The majority of studies show no differences between anatomic single-bundle and double-bundle ACL reconstruction with respect to patient-reported outcome scores. Double-bundle reconstruction may provide superior knee joint laxity measurements compared with the single-bundle technique. Following ACL reconstruction, the age and activity level of a patient are predictive of his or her time of return to sports and reinjury. Concomitant meniscal and/or cartilage damage at the time of surgery, in addition to a persistent knee motion deficit, are associated with the development of osteoarthritis after ACL reconstruction.

A surgical trick for adjusting an inaccurate guide pin to the center of the tibial footprint in anatomic single-bundle anterior cruciate ligament reconstruction

Anatomic positioning of the graft in anatomic anterior cruciate ligament reconstruction is the key to improved knee stability, restoration of normal knee kinematics, and the prevention of long-term joint degeneration. We have developed a technique for adjusting inaccurate drill guide placement to the center of the tibial footprint in anatomic single-bundle anterior cruciate ligament reconstruction. This technique can solve the inaccurate drill guide placement problems that may be encountered during this surgical procedure.

Evaluation of ACL mid-substance cross-sectional area for reconstructed autograft selection

PURPOSE

The purpose of this study was to compare the size of the native ACL mid-substance cross-sectional area and the size of commonly used autografts. Hypothesis of this study was that the reconstructed graft size with autografts would be smaller than the native ACL size.

METHODS

Twelve non-paired human cadaver knees were used. The ACL was carefully dissected, and the mid-substance of the ACL was cross-sectioned parallel to the articular surface of the femoral posterior condyles at 90 degrees of knee flexion. The size of the cross-sectional area of the ACL, and the femoral and tibial footprints were measured using Image J software (National Institute of Health). The semitendinosus tendon (ST) and the gracilis (G) tendon were harvested and prepared for ACL grafts. Simulating an ST graft, the ST was cut in half. The bigger half was regarded as the antero-medial (AM) bundle, and the remaining half was regarded as the postero-lateral (PL) bundle. Simulating an ST-G graft, the bigger half of the ST and G were regarded as the AM bundle, and the smaller half of the ST was regarded as the PL bundle. Each graft diameter was measured, and the graft area was calculated. Simulating a rectangular bone-patella tendon-bone (BPTB) graft, a 10-mm-wide BPTB graft was harvested and the area calculated.

RESULTS

The sizes of the ACL mid-substance cross-sectional area, femoral and tibial ACL footprint were 46.9 ± 18.3, 60.1 ± 16.9 and 123.5 ± 12.5 mm(2), respectively. The average areas of the ST, ST-G, and BPTB grafts were 52.0 ± 3.8, 64.4 ± 6.2, and 40.8 ± 6.7 mm(2), respectively. The ST and BPTB grafts showed no significant difference in graft size when compared with the ACL cross-sectional area.

CONCLUSION

ST and BPTB autografts were able to reproduce the native size of the ACL mid-substance cross-sectional area. The ST-G graft was significantly larger than the ACL cross-sectional area. For clinical relevance, ST and BPTB grafts are recommended in order to reproduce the native size of the ACL in anatomical ACL reconstruction with autograft.

A prospective randomized study comparing double- and single-bundle techniques for anterior cruciate ligament reconstruction

BACKGROUND

The aim of the study was to compare the results after arthroscopic anterior cruciate ligament (ACL) reconstruction using either the double-bundle or single-bundle technique with hamstring tendon autografts in an unselected group of patients.

HYPOTHESIS

Double-bundle ACL reconstruction will render a better outcome on the pivot-shift test.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A randomized series of 103 patients (33 women, 70 men; median age, 27 years; range, 18-52 years) with a unilateral ACL rupture underwent anatomic ACL reconstruction. The double-bundle technique was used in 53 patients, and the single-bundle technique was used in 50 patients. The ACL footprint was visualized, and the femoral tunnel was drilled through the anteromedial portal; interference screw fixation was used at both ends. The patients were examined preoperatively and at a median of 26 months (range, 22-42 months) after the reconstruction by a blinded observer. The primary variable was the pivot-shift test.

RESULTS

At 2-year follow-up, 98 patients (93%) were examined. Clinical assessments at follow-up revealed no significant differences between the double-bundle and single-bundle groups in terms of the pivot-shift test, KT-1000 arthrometer laxity measurements, manual Lachman test, range of motion, Lysholm knee scoring scale, Tegner activity scale, Knee Injury and Osteoarthritis and Outcome Score (KOOS), 1-legged hop test, and square hop test. A significant improvement was seen in both groups compared with the preoperative values in terms of most clinical assessments.

CONCLUSION

In this prospective randomized study, the primary variable, the pivot-shift test, and other subjective and objective outcome variables revealed no significant differences between the double-bundle and single-bundle techniques at 2 years after ACL reconstruction in an unselected group of patients.

Computed tomography analysis of the femoral tunnel position and aperture shape of transportal and outside-in ACL reconstruction: do different anatomic reconstruction techniques create similar femoral tunnels?

BACKGROUND

The desire to perform independent femoral drilling in anterior cruciate ligament (ACL) reconstruction has prompted interest in both the transportal (TP) and outside-in (OI) techniques. However, there have been no in vivo studies on the differences in femoral aperture shape between the 2 techniques.

PURPOSE

To evaluate the femoral tunnel aperture shape and femoral tunnel position between ACL reconstruction using the TP and OI techniques.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 80 patients were randomized to undergo double-bundle ACL reconstruction using either the TP (n = 40) or OI (n = 40) technique. The femoral tunnel aperture shape (height/width ratio), aperture axis angle (angle between the aperture axis and femoral shaft axis), and femoral tunnel position were assessed by computed tomography.

RESULTS

The mean height/width ratio of the anteromedial (AM) femoral tunnels in the TP group (1.35 ± 0.16) was significantly more ellipsoidal than that in the OI group (1.22 ± 0.16) (P = .008). There was no difference between the 2 groups in the posterolateral (PL) tunnels (TP, 1.32 ± 0.23; OI, 1.35 ± 0.29; P = .99). The mean aperture axis angle of the PL femoral tunnels in the OI group was significantly more perpendicular to the femoral shaft axis and had a more variable range than that in the TP group (P = .007). The mean PL femoral tunnel position in the OI group was significantly shallower and a little higher than that in the TP group (P = .006).

CONCLUSION

The TP technique revealed a more ellipsoidal AM femoral tunnel aperture than the OI technique. The mean PL femoral tunnel position in the OI group was significantly shallower than that in the TP group, with a more variable and more perpendicular aperture axis angle to the femoral shaft axis.

CLINICAL RELEVANCE

The TP technique might be more advantageous than the OI technique in terms of graft coverage, with a more ellipsoidal AM femoral tunnel and more horizontal and consistent PL aperture axis angle. In addition, it may be useful to consider the shallower PL femoral tunnel positions created with the OI technique.

Restoration of sagittal and transverse plane proprioception following anatomic double-bundle ACL reconstruction

PURPOSE

To investigate the restoration of knee proprioception after anatomic double-bundle ACL reconstruction.

METHODS

Eleven subjects who underwent anatomic double-bundle ACL reconstruction (12.5-15 months following surgery) and eleven healthy control subjects participated in the study. Sagittal and transverse plane threshold to detect passive motion (TTDPM) were assessed utilizing a customized isokinetic dynamometer by passively rotating the tibia about a fixed femur in both the sagittal plane and transverse plane at 0.25°/s until the subject signalled recognition of movement and movement direction. Based on the normality assumption, either dependent t test or Wilcoxon test was utilized to determine whether significant differences were present between the ACL-reconstructed and the uninjured contralateral limbs. Independent t test or Mann-Whitney test was utilized to compare between the ACL-reconstructed/uninjured contralateral and the external control limbs.

RESULTS

There were no significant differences in TTDPM measurement in eleven out of twelve comparisons between the ACL-reconstructed and the uninjured contralateral/external control limbs. The only statistical significant difference was found on TTDPM towards internal rotation direction from the externally rotated-test position between the ACL-reconstructed and the uninjured contralateral limbs (p = 0.01).

CONCLUSIONS

Based on a small sample of eleven subjects, the current results indicate a restoration of both sagittal and transverse plane TTDPM following the anatomic double-bundle ACL reconstruction.

LEVEL OF EVIDENCE

III.

Anatomic Anterior Cruciate Ligament Reconstruction: Current Concepts and Future Perspective

Anatomic anterior cruciate ligament (ACL) reconstruction is common procedure performed by orthopedic surgeons, particularly in association with sports-related injuries. Whereas traditional reconstruction techniques used a single bundle graft that was typically placed in a non-anatomic position, a renewed interest in anatomy has facilitated the popularization of anatomic reconstruction techniques. Recently, a focus has been placed on individualizing ACL surgery based on each patient's native anatomical characteristics (e.g., insertion site size, notch size, and shape), thereby dictating the ultimate procedure of choice. As subjective outcome measurements have demonstrated varying outcomes with respect to single- versus double-bundle ACL reconstruction, investigators have turned to more objective techniques, such as in vivo kinematics, as a means of evaluating joint motion and cartilage contact mechanics. Further investigation in this area may yield important information with regard to the potential progression to osteoarthritis after ACL reconstruction, including factors affecting or preventing it.

A quantitative technique to create a femoral tunnel at the averaged center of the anteromedial bundle attachment in anatomic double-bundle anterior cruciate ligament reconstruction

Background

In the anatomic double-bundle ACL reconstruction, 2 femoral tunnel positions are particularly critical to obtain better clinical results. Recently, a few studies have reported quantitative identification methods for posterolateral (PL) bundle reconstruction. Concerning anteromedial (AM) bundle reconstruction, however, no quantitative clinically available methods to insert a guide wire at the center of the direct attachment of the AM mid-substance fibers have been reported to date.

Methods

First, we determined the center of the femoral attachment of the AM mid-substance fibers using 38 fresh frozen cadaveric knees. Based on this anatomical sub-study, we developed a quantitative clinical technique to insert a guide wire at the averaged center for anatomic double-bundle ACL reconstruction. In the second clinical sub-study with 63 patients who underwent anatomic ACL reconstruction with this quantitative technique, we determined the center of an actually created AM tunnel. Then, we compared the results of the second sub-study with those of the first sub-study to validate the accuracy of the quantitative technique. In both the sub-studies, we determined the center of the anatomical attachment and the tunnel outlet using the “3-dimensional clock” system. The tunnel outlet was evaluated using the “transparent” 3-dimensional computed tomography.

Results

The averaged center of the direct attachment of the AM bundle midsubstance fibers was located on the cylindrical surface of the femoral intercondylar notch at “10:37” (or “1:23”) o’clock orientation in the distal view and at 5.0-mm from the proximal outlet of the intercondylar notch (POIN) in the lateral view. The AM tunnel actually created in ACL reconstruction was located at “10:41” (or “1:19”) o’clock orientation in the average and at 5.0-mm from the POIN. There was no significant difference between the 2 center locations.

Conclusions

The quantitative technique enabled us to easily create the femoral AM tunnel at the averaged center of the direct attachment of the AM bundle midsubstance fibers with high accuracy. This study reported information on the geometric location of the femoral attachment of the AM bundle and a clinically useful technique for its anatomical reconstruction.

Anatomic double-bundle reconstruction techniques result in graft obliquities that closely mimic the native anterior cruciate ligament anatomy

BACKGROUND

It has been reported previously that single-bundle anterior cruciate ligament (ACL) reconstruction with more accurate restoration of the footprint of the native ACL fails to restore the graft obliquity of the native ACL in the coronal plane. Whether double-bundle ACL reconstruction restores the graft obliquity of each bundle of the native ACL has not yet been determined.

HYPOTHESIS

Anatomic double-bundle ACL reconstruction using transportal (TP) and outside-in (OI) techniques can restore the graft obliquities of both anteromedial (AM) and posterolateral (PL) bundles in the native ACL in both sagittal and coronal planes.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Seventy-six patients underwent anatomic double-bundle ACL reconstruction. Patients were randomized to 2 groups to undergo either TP or OI tibial tunnel-independent anatomic ACL reconstruction. All participants underwent postoperative magnetic resonance imaging of both knees, and the native ACL obliquity was determined using the participant's contralateral knee. Graft obliquities were determined by measuring the angles between the center line of the graft and the surface line of the tibial plateau, and the obliquities of paired knees were compared. Graft obliquities were analyzed in each group.

RESULTS

In the sagittal plane, the mean AM graft obliquity was 54.2° on the operated side and 54.6° on the nonoperated side, and the difference between sides was not statistically significant (P = .352). The mean PL graft obliquity in the sagittal plane was 54.1° on the operated side and 53.0° on the nonoperated side, and the difference between sides was also not statistically significant (P = .228). In the coronal plane, the mean AM graft obliquity was 73.8° on the operated side and 73.4° on the nonoperated side, and the mean PL graft obliquity was 65.5° on the operated side and 66.4° on the nonoperated side. There were no statistically significant differences between sides (P = .418 for AM graft; P = .328 for PL graft). Differences in the paired graft obliquities in each group were also statistically insignificant between the TP and OI groups.

CONCLUSION

Both TP and OI anatomic double-bundle reconstruction techniques can result in graft obliquities in both bundles that resemble the native ACL in both sagittal and coronal planes.

CLINICAL RELEVANCE

Double-bundle ACL reconstruction techniques might more closely restore the normal kinematics of the native ACL by restoring the normal obliquity of both ACL bundles.