Femoral Anteromedial Research Articles

A new remnant preservation technique reduces bone tunnel enlargement after anatomic double-bundle anterior cruciate ligament reconstruction.

To investigate the effect of a new remnant preservation technique with a focus on remnant continuity on postoperative femoral and tibial tunnel enlargement after anatomical double-bundle anterior cruciate ligament reconstruction (ACLR). A total of 150 knees were divided into three groups: Preservation Group (Group P: 49 knees), wherein the remnant continuity remained after tunnel creation; Resection Group (Group R: 47 knees), wherein the remaining remnant was resected, and Absent Group (Group A: 54 knees), wherein the remnant had no femoral attachment before tunnel creation. In Group P, the remnant maintained continuity, and the anteromedial (AM) and posterolateral (PL) bundles were positioned anterior and posterior to the remnant, respectively. Computed tomographic scans were performed at 1week and 1year after surgery, and the cross-sectional area of each tunnel aperture was measured. Tunnel enlargement was compared among the three groups by one-way analysis of variance (ANOVA) and the Bonferroni test. Univariate and multivariate logistic analyses were performed to identify the risk factors for tunnel enlargement in demographic and radiographic data. For femoral AM tunnels, the tunnel enlargement of Group P was significantly smaller than Groups R and A (p < 0.001), femoral PL (p < 0.001 vs. R and A), tibial AM (p < 0.001 vs. R, 0.002 vs. A), and tibial PL (p < 0.001 vs. R, 0.002 vs. A). There was no significant difference between Groups R and A. Multivariate logistic analysis showed that remnant preservation was a significant factor in reducing tunnel enlargement in the femoral AM, femoral PL, tibial AM, and tibial PL. The new remnant-preserving anatomical double-bundle ACLR, which preserves the continuity of the remnant, prevented all bone tunnel enlargement at 1year postoperatively. Level III.

Radiographic evaluation of the tunnel position in single and double bundle anterior cruciate ligament reconstruction.

Aim To evaluate tunnel positioning on radiographs in singlebundle (SB) and double-bundle (DB) anterior cruciate ligament (ACL) reconstruction, to evaluate if measurement is accurate and reproducible. Methods Radiographs of 30 SB and 30 DB ACL reconstruction were reviewed by two examiners who measured tunnel positioning with the quadrant method on the femur (a=depth, b=height) and the Amis and Jakob method on the tibia. Intra- and inter-observer reliability were evaluated with intra-class correlation coefficient (ICC). Results A radiographic analysis was completed in all patients in a SB-group and in 27 in a DB-group (p>0.05). Intra-observer reliability was almost perfect on femoral (ICC: a=0.85, b=0.83) and tibial (ICC=0.87) side in the SB-group. In the DB-group, it was almost perfect for tibial anteromedial (AM) and posterolateral (PL) bundles (ICC: AM=0.84, PL=0.81) and for femoral PL bundle (ICC: a=0.83, b=0.82), and substantial for femoral AM bundle (ICC: a=0.78, b=0.74). Inter-observer reliability was almost perfect on tibial (ICC=0.81) and femoral (ICC: a=0.81, b=0.87) side in the SB-group, and substantial on tibial (ICC: AM=0.71, PL=0.77) and femoral (ICC: AM a=0.73, b=0.78; PL a=0.74, b=0.76) side in the DB-group. Standard deviation (SD) was low (±9%) with respect to the centre of tunnel(s). Conclusion The quadrant method and the Amis and Jakob method are accurate and reproducible measurement methods. Also, as SD was low, an outside-in approach with a front-entry guide, which is free-hand positioned, can be postulated as a reliable method to locate the femoral tunnel in SB reconstruction and the AM bundle in DB reconstruction.

L’amplificateur de brillance est-il nécessaire dans les reconstructions double faisceau du ligament croisé antérieur? Une étude prospective randomisée

IntroductionProperly placed tibial and femoral tunnels in anterior cruciate ligament (ACL) reconstruction are important because tunnel misplacement can cause abnormal changes in graft tension patterns, resulting in postoperative knee laxity. To overcome the inaccuracy of tunnel position in ACL reconstruction, intraoperative fluoroscopy has been proven to be a useful method in previous studies focusing on the tunnel position in single-bundle reconstruction, but few studies are available on the efficacy and necessity of intraoperative fluoroscopy for double-bundle (DB) reconstruction. The purpose of this prospective randomized case-control study was to evaluate the effect of intraoperative fluoroscopy on femoral and tibial tunnel position in anatomic DB ACL reconstruction using a postoperative tunnel position in a three-dimensional computed tomography (3D-CT). HypothesisIntraoperative fluoroscopy during ACL DB reconstruction could make an appropriate tunnel position closer to the anatomical center compared to conventional fluoroscopy-free procedure. Material and methodsSixty patients undergoing ACL DB reconstruction (30 fluoroscopy-free reconstruction group and 30 in fluoroscopy-assisted reconstruction group) were included in this prospective study, and randomly allocated into two groups. Mean values of the percentage distance of femoral and tibial tunnel center in a 3D-CT were compared between the two groups. Knee laxity (the anterior translation and pivot-shift grade) and clinical outcomes were also compared at the last follow-up. ResultsThere was a significant difference only in femoral anteromedial (AM) bundle tunnel position, but not in femoral posterolateral (PL) bundle, tibial AM, or PL bundle tunnel position between the two groups. Femoral AM bundle tunnel in the fluoroscopy-assisted reconstruction group showed significantly (p=0.005) deeper position compared to that in the fluoroscopy-free reconstruction group. There was no significant difference in anterior translation, pivot-shift grade, or clinical outcomes between the two groups. DiscussionFluoroscopy-assisted ACL DB reconstruction can make deeper placement of the femoral AM bundle than the conventional ACL DB reconstruction. Level of evidenceII, prospective randomized controlled trial.

Is intraoperative fluoroscopy necessary in anterior cruciate ligament double-bundle reconstruction? A prospective randomized controlled trial

IntroductionProperly placed tibial and femoral tunnels in anterior cruciate ligament (ACL) reconstruction are important because tunnel misplacement can cause abnormal changes in graft tension patterns, resulting in postoperative knee laxity. To overcome the inaccuracy of tunnel position in ACL reconstruction, intraoperative fluoroscopy has been proven to be a useful method in previous studies focusing on the tunnel position in single-bundle reconstruction, but few studies are available on the efficacy and necessity of intraoperative fluoroscopy for double-bundle (DB) reconstruction. The purpose of this prospective randomized case-control study was to evaluate the effect of intraoperative fluoroscopy on femoral and tibial tunnel position in anatomic DB ACL reconstruction using a postoperative tunnel position in a three-dimensional computed tomography (3D-CT). HypothesisIntraoperative fluoroscopy during ACL DB reconstruction could make an appropriate tunnel position closer to the anatomical center compared to conventional fluoroscopy-free procedure. Material and methodsSixty patients undergoing ACL DB reconstruction (30 fluoroscopy-free reconstruction group and 30 in fluoroscopy-assisted reconstruction group) were included in this prospective study, and randomly allocated into two groups. Mean values of the percentage distance of femoral and tibial tunnel center in a 3D-CT were compared between the two groups. Knee laxity (the anterior translation and pivot-shift grade) and clinical outcomes were also compared at the last follow-up. ResultsThere was a significant difference only in femoral anteromedial (AM) bundle tunnel position, but not in femoral posterolateral (PL) bundle, tibial AM, or PL bundle tunnel position between the two groups. Femoral AM bundle tunnel in the fluoroscopy-assisted reconstruction group showed significantly (p=0.005) deeper position compared to that in the fluoroscopy-free reconstruction group. There was no significant difference in anterior translation, pivot-shift grade, or clinical outcomes between the two groups. DiscussionFluoroscopy-assisted ACL DB reconstruction can make deeper placement of the femoral AM bundle than the conventional ACL DB reconstruction. Level of evidenceII, prospective randomized controlled trial.

Effects of Remnant Tissue Preservation on Tunnel Enlargement After Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Using the Hamstring Tendon.

Background:The effects of remnant tissue preservation on tunnel enlargement after anatomic double-bundle anterior cruciate ligament (ACL) reconstruction have not yet been established.Hypothesis:The preservation of ACL remnant tissue may significantly reduce the degree and incidence of tunnel enlargement after anatomic double-bundle ACL reconstruction, while the remnant-preserving procedure may not significantly increase the incidence of tunnel coalition after surgery.Study Design:Cohort study; Level of evidence, 2.Methods:A total of 79 patients underwent anatomic double-bundle ACL reconstruction. Based on the Crain classification of ACL remnant tissue, 40 patients underwent the remnant-preserving procedure (group P), and the remaining 39 patients underwent the remnant-resecting procedure (group R). There were no differences between the 2 groups concerning all background factors, including preoperative knee instability and intraoperative tunnel positions. All patients were examined using computed tomography and a standard physical examination at 2 weeks and 1 year after surgery.Results:During surgery, the femoral and tibial anteromedial (AM) tunnel sizes in both groups averaged 6.6 and 6.5 mm, respectively. The femoral and tibial posterolateral (PL) tunnel sizes in both groups averaged 6 and 6 mm, respectively. There were no differences in the intraoperative tunnel positions and tunnel sizes between groups. Concerning the femoral AM tunnel, the degree of tunnel enlargement in the oblique coronal and oblique axial views in group P was significantly less than that in group R (P = .0068 and .0323, respectively). Regarding the femoral AM tunnel cross-sectional area, the degree and incidence of tunnel enlargement in group P were significantly less than those in group R (P = .0086 and .0278, respectively). There were no significant differences in tunnel coalition between groups. In each group, there were no significant relationships between tunnel enlargement and each clinical outcome.Conclusion:Remnant preservation in anatomic double-bundle ACL reconstruction reduced enlargement of the femoral AM tunnel and did not increase the incidence of tunnel coalition. This is one of the advantages of remnant-preserving ACL reconstruction.

The evolution of primary double-bundle ACL reconstruction and recovery of early post-operative range of motion.

The aim of this study was to analyse early post-operative range of motion (ROM) as our anatomic double-bundle (DB) anterior cruciate (ACL) reconstruction technique with respect to tunnel placement evolved. It is the hypothesis of this study that more anatomic placement of the femoral insertion site of the anteromedial (AM) bundle of the ACL results in better restoration of early post-operative knee range of motion. Two methods of DB ACL reconstruction regarding more accurate placement of the femoral AM tunnel in relation to its anatomic origin were compared. Patients presenting for 1- and 3-month post-operative clinical visits were examined for passive extension and active flexion by members of the clinical staff. Only patients undergoing primary DB reconstruction with allograft were included in the analyses. To determine the effects of the modified AM bundle placement on recovery of post-operative ROM, patients undergoing surgery in the 6months before July 2006 (Group A, n=50) were compared to patients undergoing surgery in the 6months after July 2006 (Group B, n=49). A total of 99 patients met the inclusion criteria. More accurate placement of the AM bundle of the ACL was associated with a smaller side-to-side difference in flexion at 1month (n.s.) and at 3months (3° reduction, p<0.03) after surgery. There was no effect on extension (n.s.) CONCLUSION: More anatomic placement of the femoral insertion of the AM bundle was associated with improved knee flexion. The study translates the findings of previous anatomic basic science research to demonstrate improved restoration of normal joint motion. This ideally leads to improved long-term clinical outcomes and maintenance of joint and cartilage health. III.

Anatomic assessment of femoral tunnel by transtibial drilling technique in double-bundle anterior cruciate ligament reconstruction: an in vivo study

ObjectiveTo evaluate the anatomy of femoral tunnels created by simulated transtibial technique in double-bundle anterior cruciate ligament (ACL) reconstruction. MethodsTwo tibial tunnels, anteromedial (AM) and posterolateral (PL), were drilled 45° and 55° to tibial plateau respectively. On the femoral side, the AM and PL tunnels were drilled through anteriomedial portal. After the four tunnels were established, the shaft of a reamer was introduced into the joint through tibial tunnel and reached against the lateral wall of intercondylar notch. The position that the reamer shaft can reach was marked and recorded. ResultsNeither femoral AM nor PL tunnel opening can be fully or partially reached by the reamer shaft through the tibial AM tunnel in all cases. The evaluation through the tibial PL tunnel showed that only in 8 of 50 cases (16%) the femoral AM tunnel opening and in 4 cases (8%) the PL opening can be fully reached. On the other hand, in 12 cases (24%) the femoral AM tunnel opening and in 10 cases (20%) the PL opening can be partially reached by the shafts through the tibial PL tunnel. ConclusionThe result strongly suggests that transtibial technique is not well competent for femoral tunnel drilling in anatomic double-bundle ACL reconstruction as we have hypothesized.

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

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. 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. 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). 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.

MRI evaluation of the four tunnels of double-bundle ACL reconstruction

The double-bundle (DB) reconstruction of the anterior cruciate ligament (ACL) has gained popularity in recent years. The positioning of anteromedial (AM) and posterolateral (PL) tunnels is aimed at the anatomic femoral and tibial attachments of AM and PL bundles of the native ACL. To use magnetic resonance imaging (MRI) to evaluate the tunnel locations and tunnel findings in DB ACL reconstruction. Sixty-six patients with DB ACL reconstruction were evaluated with 1.5-T MRI 2 years postoperatively. Two musculoskeletal radiologists separately measured the locations and the diameters of the tunnels. Inter-observer agreements were estimated according to the method of Bland and Altman. In the femur, the mean AM tunnel location was 32% from the proximal condylar surface and 18% from the notch roof. The mean PL tunnel location was 42% and 43%, respectively. In the tibia, the mean AM tunnel location was 54% of the lateral-to-medial tibial width and 42% of the anterior-to-posterior tibial depth. The mean PL tunnel location was 54% and 56%, respectively. The mean tunnel enlargement was 3.8 mm (56%). Tunnel communication was seen in seven patients (11%) in the femur and in 19 patients (29%) in the tibia. Greater femoral AM tunnel distance from the proximal condylar surface was associated with more tunnel enlargement, and more posterior tibial PL tunnel location was associated with less tunnel enlargement. The tunnel locations of DB ACL reconstruction can be evaluated with MRI. Tunnel location was associated with tunnel enlargement that in turn was associated with tunnel communication.

Comparison of transportal inside-out and outside-in femoral drilling techniques in anatomic ACL reconstruction

The purpose of this study was to examine tunnel length and incidence of posterior wall breakage during drilling of the femoral anteromedial (AM) tunnel in anatomic anterior cruciate ligament (ACL) reconstruction and compare those results between inside-out (transportal) and outside-in techniques. The study population comprised 68 patients (30 females and 38 males) with a mean age at surgery of 24.1 years (range, 14–45 years). In the reconstructive procedure, the femoral AM bone tunnel was drilled inside-out through the anteromedial portal in 32 knees, while the outside-in technique was employed in the remaining 36 knees. The intra-articular aperture of the femoral AM tunnel was located behind the resident's ridge in all knees as assessed by the postoperative computed tomography (CT) image. Length of the bony tunnel was measured with the depth gauge intraoperatively, while incidence of the posterior bony wall breakage (blowout) was assessed on the postoperative CT image. Thereafter, the obtained results were compared between the groups (transportal inside-out drilling vs. outside-in drilling). Knee stability was assessed at 12 months using a KT arthrometer. The mean length of the femoral AM tunnel in the inside-out group (32.2 ± 4.7 mm) was significantly shorter than that in the outside-in group (36.3 ± 4.6 mm). In the inside-out groups, posterior wall breakage was encountered in one patient (3.6%), and a lack of the tunnel length precluded the use of the EndoButton CL in three patients (10.7%). By contrast, no such complication was encountered in the outside-in group. No significant difference in knee stability was detected between the groups. During the femoral AM tunnel drilling in the current anatomic ACL reconstruction, the potential risks for the problems such as short tunnel length and posterior wall breakage were higher in the transportal inside-out drilling than the outside-in procedure. Adoption of the outside-in technique can reduce the risk of complications associated with femoral drilling. Level of evidenceLevel IV, case series.

Correlation between femoral guidewire position and tunnel communication in double bundle anterior cruciate ligament reconstruction.

PurposeThe object of this study was to determine the shortest possible distances of antero-medial (AM) and postero-lateral (PL) guide wire tunnel positions required to prevent femoral bone tunnel communication in double-bundle anterior cruciate ligament (ACL) reconstruction using human cadaver knees.Materials and MethodsThe centers of femoral AM and PL bundles of 16 cadaveric knees were drilled with guide wires and the distances of guide wires, were measured upon entrance into the bone. Femoral tunnel drilling was performed using transportal technique. The diameters of AM and PL graft were 8 mm and 6 mm, respectively. CT scans were taken on each knee, and 3-dimensional models were constructed to identify the femoral tunnel position and to create AM and PL tunnel virtual cylinders. Thickness of the bone bridge between the two tunnels was measured.ResultsIn four out of six specimens, in which the guide wires were placed at less than or equal to 9 mm, communication was noted. In specimens with guide wires placed at distances greater than or equal to 10 mm, communication was not noted. The two groups showed a statistically significant difference (p=0.008). In cases where the distance between the AM and PL femoral tunnel guide wires was 12 mm, the bone bridge thickness was greater than 2 mm along the tunnel.ConclusionThe technique for double bundle-anterior cruciate ligament (DB-ACL) reconstruction that we show here can avoid bone tunnel communication when AM and PL femoral guide wires are placed at least 10 mm apart, and 12 mm should be kept to preserve 2 mm bone bridge thickness.

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

BackgroundIn 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.MethodsFirst, 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.ResultsThe 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.ConclusionsThe 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.

Analysis of tunnel widening after double-bundle ACL reconstruction

The purpose of this study was to evaluate the tunnel widening using a multi-planar reformation of MRI (Magnetic Resonance Imaging) in the orientation of the tunnel. The hypotheses of this study were as follows: (1) tunnel widening would be reduced with the above-mentioned technique, (2) the degree of tunnel widening would be different at the site of the tunnels, and (3) the time interval from surgery to MRI acquisition would affect the magnitude of tunnel widening. Forty double-bundle ACL reconstructed patients who underwent postoperative MRI were enrolled in this study. The postoperative MRI was performed at 26.7±7.4months in terms of time. The tunnel widening was examined using a multi-planar reformation of MRI in the orientation of the tunnel. Site-specific analysis was performed according to the depth (the entrance, mid, and exit portion) and wall (anterior, posterior, medial, and lateral walls). The correlation between MRI and widening was also evaluated. The mean tunnel widening of the femoral AM (Anteromedial), femoral PL (Posterolateral), tibial AM, and tibial PL in terms of the most widened diameter was 1.9 (25.4), 2.1 (30.8), 2.5 (32.8), and 3.2mm (44.5%), respectively. The tibial PL tunnel showed significant widening than the other tunnels. At the entrance, tunnel widening occurred mostly, followed by the order of the mid and exit portion. Correlation analysis of the time interval of MRI acquisition and tunnel widening showed little association. Tunnel widening after a double-bundle ACL reconstruction using an outside-in technique with press-fitting of the graft was acceptable compared to previously published studies. The tibial PL tunnel showed the most widening among the 4 tunnels examined with the tunnel entrance being most widened area. Therapeutic case series, Level IV.

PCL to graft impingement pressure after anatomical or non-anatomical single-bundle ACL reconstruction

Anterior cruciate ligament (ACL) graft impingement against the posterior cruciate ligament (PCL) has been postulated, but not thoroughly investigated. To evaluate PCL impingement pressure and biomechanical stability with different tibial and femoral tunnel positions in ACL reconstruction. In 15 porcine knees, the impingement pressure between ACL and PCL was measured using pressure sensitive film before and after ACL single-bundle reconstruction. ACL reconstructions were performed in each knee with three different tibial and femoral tunnel position combinations: (1) tibial antero-medial (AM) tunnel to femoral AM tunnel (AM-AM), (2) tibial postero-lateral (PL) tunnel to femoral High-AM tunnel (PL-High-AM) and (3) tibial AM tunnel to femoral High-AM tunnel (AM-High-AM). Anterior tibial translation (ATT) was evaluated after each ACL reconstruction using robotic/universal force-moment sensor testing system. There was no significant difference of the impingement pressure between AM and AM, PL-High-AM reconstructed groups and intact ACL. Only AM-High-AM ACL reconstruction group showed significantly higher impingement pressure compared with intact ACL. With regard to ATT, AM-AM group had significantly higher stiffness than PL-High-AM group. Anatomical ACL reconstruction does not cause PCL impingement and it has biomechanical advantage in ATT when compared with non-anatomical ACL reconstructions in porcine knee. For the clinical relevance, in the anatomical ACL reconstruction, no ACL-PCL impingement is found.

In vitro and in vivo AM and PL tunnel positioning in anatomical double bundle anterior cruciate ligament reconstruction

There have been few studies investigating the correct anatomical femoral and tibial tunnel placement in double bundle anterior cruciate ligament (ACL) reconstruction. To compare anteromedial (AM) and posterolateral (PL) tunnel positions in anatomical double bundle ACL reconstruction in human cadaver and patient knees. Fifteen fresh-frozen non-paired adult human knees and 27 patients (27 knees) were evaluated. In the cadaver knees, AM and PL bundles were identified by their difference in tension patterns. Their femoral centers were marked with a K-wire, and cut from the femoral insertion site. After this, each bundle was divided at the tibial side. The center of each bundle insertion was again marked with a K-wire, and 5-7-mm tunnels were drilled with transportal or outside-in technique. In patient knees, each tunnel was made according to the native ACL foot print and bony landmarks using transtibial technique (n=5) and transportal technique (n=22). Tunnel placement was evaluated using a C-arm X-ray device and 3D CT. For the femoral side assessment, Bernard and Hertel's technique was used. For the tibial side assessment, Amis and Jakob's technique was used. The femoral AM tunnel in the cadaver knees was placed in a significantly deeper position when compared to patient knees. There was no significant difference in the AM vertical placement or in the PL tunnel placement in the femur. No significant differences were observed in the tibial tunnel placements between cadaver and patient knees. In vivo positioning of the femoral AM bundle differed significantly from the in vitro positioning.

Arthroscopically Pertinent Landmarks for Tunnel Positioning in Single-Bundle and Double-Bundle Anterior Cruciate Ligament Reconstructions

Background: Quantification of the overall anterior cruciate ligament (ACL) and anteromedial (AM) and posterolateral (PL) bundle centers in respect to arthroscopically pertinent bony and soft tissue landmarks has not been thoroughly assessed. Hypothesis: A standardized anatomical measurement method can quantitate the locations of the ACL and AM and PL bundle centers in reference to each other and anatomical landmarks. Study Design: Descriptive laboratory study. Methods: Quantification of the ACL and its bundle attachments was performed on 11 cadaveric knees using a radio frequency-tracking device. Results: The tibial ACL attachment center was 7.5 mm medial to the anterior horn of the lateral meniscus, 13.0 mm anterior to the retro-eminence ridge, and 10.5 mm posterior to the ACL ridge. The femoral ACL attachment center was 1.7 mm proximal to the bifurcate ridge and 6.1 mm posterior to the lateral intercondylar ridge. The tibial AM attachment center was 8.3 mm medial to the anteromedial aspect of the lateral meniscus anterior horn, 17.8 mm anterior to the retro-eminence ridge, and 5.6 mm posterior to the ACL ridge. The femoral AM attachment center was 4.8 mm proximal to the bifurcate ridge and 7.1 mm posterior to the lateral intercondylar ridge. The tibial PL bundle attachment center was 6.6 mm medial to the posteromedial aspect of the lateral meniscus anterior horn, 10.8 mm anteromedial to the root attachment of the lateral meniscus posterior horn, and 8.4 mm anterior to the retro-eminence ridge. The femoral PL bundle attachment center was 5.2 mm distal to the bifurcate ridge and 3.6 mm posterior to the lateral intercondylar ridge. Conclusion: The authors developed a comprehensive compilation of measurements of arthroscopically pertinent bony and soft tissue landmarks that quantitate the ACL and its individual bundle attachment centers on the tibia and femur. Clinical Relevance: These clinically relevant arthroscopic landmarks may enhance single- and double-bundle ACL reconstructions through improved tunnel placement.

Size Variability of the Human Anterior Cruciate Ligament Insertion Sites

Background: Current trends in anterior cruciate ligament reconstruction (ACLR) have been toward anatomical reconstruction that restores the normal size and location of the anterior cruciate ligament insertions and its 2 bundles, the posterolateral (PL) and anteromedial (AM) bundles. This has resulted in a more individualized approach to ACLR. Several studies have shown that the size of the anterior cruciate ligament insertion sites is variable; however, these studies are limited by use of relatively small sample sizes and cadaveric specimens. Purpose: This study was undertaken to evaluate the in vivo size variability of the anterior cruciate ligament insertion sites and its AM and PL bundles during arthroscopy in a large series of patients and to correlate these findings with individuals’ physical characteristics (height, weight, and body mass index). Study Design: Cross-sectional study; Level of evidence, 3. Methods: In 137 patients undergoing ACLR during the first 6 months after injury, the femoral and tibial anterior cruciate ligament insertion sites and the 2 bundles were identified, marked with electrocautery, and measured with an arthroscopic ruler. Additionally, physical characteristics of the patients, including self-reported height, weight, and body mass index, were recorded. Results: The tibial anterior cruciate ligament insertion site had a mean length of 17.0 ± 2.0 mm. The tibial AM bundle length was 9.1 ± 1.2 mm and the width was 9.2 ± 1.1 mm. The tibial PL bundle insertion site length averaged 7.4± 1.0 mm and the width averaged 7.0 ± 1.0 mm. The femoral insertion sites had a mean length of 16.5 ± 2.0 mm. The length of the femoral AM bundle insertion site averaged 9.2 ± 1.2 mm and the width averaged 8.9 ± 0.9 mm. The femoral PL bundle insertion site length averaged 7.1 ± 1.1 mm and the width averaged 6.9 ± 1.0 mm. There were significant positive correlations between patient height and weight (P < .05) with femoral and tibial anterior cruciate ligament insertion site length, tibial PL bundle insertion site length, femoral AM bundle insertion site length, and tibial AM bundle and PL bundle insertion site areas. However, the coefficients of determination values were low (1.0% to 19.4%). Conclusion: There is a large variation in size of the anterior cruciate ligament insertion sites and the AM and PL bundles. Additionally, there are significant but weak correlations between the size of the insertions and height, weight, and body mass index of the individual patient.

Impingement Pressure in the Anatomical and Nonanatomical Anterior Cruciate Ligament Reconstruction

Background: Although the literature has extensively discussed impingement after anterior cruciate ligament (ACL) reconstruction, the definition of impingement is vague, and impingement pressure has not been well investigated as a function of tunnel position. Purpose: To determine the amount of impingement pressure between the ACL and posterior cruciate ligament (PCL) and between the ACL and notch roof in the native ACL, the single-bundle ACL reconstruction with different tunnel placements, and the anatomical double-bundle ACL reconstruction. Study design: Controlled laboratory study. Methods: Fifteen fresh-frozen nonpaired human cadaver knees were used. In each knee, different femoral and tibial tunnels were created, which allowed different graft placements. A single graft was placed in 3 positions: tibial anteromedial (AM) to femoral AM (anatomical), tibial posterolateral (PL) to femoral high AM (nonanatomical/mismatch), and tibial AM to femoral high AM. Double grafts were placed in an anatomical fashion (AM to AM and PL to PL). In each case, pressure-measuring films were inserted between the ACL and roof, the ACL and PCL, and the AM and PL bundles (for double-bundle group only). Knees were then moved with 40 N of force and from full flexion to full extension, and the pressure pattern on the film was analyzed. Results: Compared with other groups, only the AM–high AM group showed significantly higher roof impingement pressure (P < .05). There was no significant difference in PCL impingement pressure between the intact ACL group and any of the reconstructed groups. No impingement pressure was observed between the grafts in the anatomical double-bundle ACL reconstruction. Conclusion: This study evaluated the effect of different tunnel placements on the impingement pressure after ACL reconstruction. Anatomical single- or double-bundle ACL reconstruction and nonanatomical tibial PL–femoral high AM ACL reconstruction do not cause roof, PCL, and interbundle impingement. Clinical relevance: Surgeons can perform the anatomical double-bundle ACL, anatomical single-bundle, and nonanatomical tibial PL–femoral high AM reconstructions as impingement-free reconstructions.

Intercondylar roof impingement pressure after anterior cruciate ligament reconstruction in a porcine model

Anterior cruciate ligament (ACL) graft impingement against the intercondylar roof has been postulated, but not thoroughly investigated. The roof impingement pressure changes with different tibial and femoral tunnel positions in ACL reconstruction. Anterior tibial translation is also affected by the tunnel positions of ACL reconstruction. The study design included a controlled laboratory study. In 15 pig knees, the impingement pressure between ACL and intercondylar roof was measured using pressure sensitive film before and after ACL single bundle reconstruction. ACL reconstructions were performed in each knee with two different tibial and femoral tunnel position combinations: (1) tibial antero-medial (AM) tunnel to femoral AM tunnel (AM to AM) and (2) tibial postero-lateral (PL) tunnel to femoral High-AM tunnel (PL to High-AM). Anterior tibial translation (ATT) was evaluated after each ACL reconstruction using robotic/universal force-moment sensor testing system. Neither the AM to AM nor the PL to High-AM ACL reconstruction groups showed significant difference when compared with intact ACL in roof impingement pressure. The AM to AM group had a significantly higher failure load than PL to High-AM group. This study showed how different tunnel placements affect the ACL-roof impingement pressure and anterior-posterior laxity in ACL reconstruction. Anatomical ACL reconstruction does not cause roof impingement and it has a biomechanical advantage in ATT when compared with non-anatomical ACL reconstructions in the pig knee. There is no intercondylar roof impingement after anatomical single bundle ACL reconstruction.

Femoral Insertions of the Anteromedial and Posterolateral Bundles of the Anterior Cruciate Ligament: Morphometry and Arthroscopic Orientation Models for Double-Bundle Bone Tunnel Placement—A Cadaver Study

The purpose of this study was to analyze the femoral insertions of the anteromedial (AM) and posterolateral (PL) bundles of the anterior cruciate ligament (ACL) and to develop arthroscopic orientation models for double-bundle (DB) bone tunnel placement. The femoral insertions of the AM and PL bundles were dissected in 50 human cadaveric knees, documented on digital photographs, and quantified with a digital image analysis system. The insertion areas of both bundles were significantly larger in men (53 mm(2) for AM and 45 mm(2) for PL) than in women (39 mm(2) for AM and 39 mm(2) for PL), and the average ACL insertion area was significantly larger in left knees than in right knees. According to the "femoral center angle model," the centers of the AM and PL bundles were horizontally aligned when the femoral shaft axis was lifted 12 degrees from the horizontal plane or when the knee was flexed to 102 degrees . In this position the center of the AM bundle was 3 to 4 mm "lower" (arthroscopic terminology) to the over-the-top position, and the distance of the PL bundle to the "shallow" articular cartilage of the lateral femoral condyle was 6 mm. According to the "modified femoral clock wall model," the average centers of the AM and PL bundles were both aligned at 1 o'clock for a left knee and at 11 o'clock for a right knee in 102 degrees of knee flexion. The average femoral insertion areas of the ACL and the AM and PL bundles were significantly larger in men compared with women and in left knees compared with right knees. According to the femoral center angle model, the AM and PL insertions are aligned horizontally in an average of 102 degrees of knee flexion, resulting in one commuted time for the AM and PL bundles in the modified femoral clock wall model. Both models support reproducible and reliable arthroscopic AM and PL bone tunnel placement. With regard to a mean anatomic anteroposterior length of the femoral ACL insertion of 14 to 15 mm, adequate DB bone tunnel placement should be possible in most cases. This study provides an anatomic description of the femoral AM and PL insertions including gender differences, landmarks, and arthroscopic orientation models for DB bone tunnel placement.