Use of transtibial aimer via the accessory anteromedial portal to identify the center of the ACL footprint

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

Purpose

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

Methods

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

Results

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

Conclusion

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

Supplementary Information

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

A comparative study of anatomical single-bundle anterior cruciate ligament reconstruction using femoral offset aimer versus freehand technique for femoral tunnel preparation

BACKGROUND

ACL reconstruction is one of the commonest orthopaedic procedures performed. There has been a shift in techniques from single bundle to double bundle to anatomic single-bundle reconstruction and also from transtibial to anteromedial method. Anteromedial technique results in more anatomic femoral tunnel with graft positioned at the native insertion site. The tunnel position is crucial for better outcome after ACL reconstruction.

PURPOSE

To compare the femoral tunnel position made by anatomic single-bundle ACL reconstruction using femoral offset aimer device versus freehand drilling with 3D computed tomography.

STUDY DESIGN

A prospective case series involving 60 patients with ACL tear who underwent anteromedial single-bundle ACL reconstruction.

METHODS

Computed tomography scans were performed on 60 knees that underwent single-bundle anteromedial ACL reconstruction with 30 cases involving femoral drilling through aimer device and another 30 cases involving freehand drilling of the tunnel. Three-dimensional models were created, and the data were analysed according to the co-ordinate axes method. Femoral tunnel position was measured in proximal-to-distal and posterior-to-anterior directions. Data from both the groups were compared with each other and already published reference data on anatomical tunnel position.

RESULTS

In the aimer group, the femoral tunnel centre on the medial wall of lateral femoral condyle was located at 35 ± 9% in the posterior-to-anterior direction and at 30 ± 12% in the proximal-to-distal direction. In the freehand group, tunnel was placed at 37 ± 10% in posterior-to-anterior and 28 ± 7% in proximal-to-distal directions. There was no significant difference in tunnel position in both the groups.

CONCLUSION

This study shows there is no significant difference between both the drilling techniques of femoral tunnel, i.e. freehand drilling and drilling with aimer device. Also, it reiterates the efficacy and utility of computed tomography and three-dimensional reconstruction in the analysis of femoral tunnel in ACL reconstruction.

Femoral offset guide facilitates accurate and precise femoral tunnel placement for single-bundle anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to compare the accuracy and precision of femoral tunnel placement by expert and novice surgeons using an offset guide for single-bundle ACL reconstruction via the anteromedial (AM) portal.

METHODS

Twenty-five single-bundle ACL reconstructions performed by a novice surgeon were matched with 25 ACL reconstructions performed by an expert surgeon, based on one-to-one propensity score matching. The same technique was used by both groups for femoral tunnel placement using a 7-mm offset guide through the AM portal. Using the Bernard and Hertel grid method for postoperative three-dimensional reconstructed computed tomography, the accuracy and precision of various tunnel positions were compared.

RESULTS

No differences were found between the proximal-distal and anterior-posterior femoral tunnel placements by the two groups (proximal-distal; 30.5% involving experts, and 32.5% by novices, n.s) (anterior-posterior; 32.6% involving experts, and 31.6% by novice, n.s). The accuracy of the femoral tunnel positions, based on the average distance from the tunnel center to the center of ACL direct insertion, was similar between the two groups (n.s). No differences were found between the groups in terms of precision of femoral tunnel positions (n.s).

CONCLUSION

Novice surgeons can achieve accuracy and precision comparable to experts in creating femoral tunnels via single-bundle ACL reconstruction through the AM portal using a femoral offset guide. We recommend the use of a femoral offset guide for ACL reconstruction during the learning phase of a novice surgeon for effective tunnel placement to reduce the learning curve required to perform accurate and reproducible ACL reconstruction.

LEVEL OF EVIDENCE

Case-control study, Level III.

Drilling through anteromedial portal with a femoral aiming device ensures a sufficient length and a proper graft position, and prevents posterior wall breakage during anterior cruciate ligament reconstruction

OBJECTIVE

The aim of this study was to evaluate the characteristics of the femoral tunnel (FT) which was drilled through the AM portal by using a femoral aimer device and AP stability of the knee.

METHODS

Thirty-eight patients, with the mean age 29.6 (range: 20-43) years, were evaluated after ACL reconstruction. The mean follow-up time was 31.9 (range: 16-57) months. The FT was drilled using a femoral aimer with different offset according to the graft size measured, through the AM portal. The semitendinous and gracilis tendon autograft was used for reconstruction. The angles of FT and the exit point on the lateral condyle were measured on AP views of the knee. AP stability of the knee was measured with the KT-2000.

RESULTS

The mean angle of FT was 46.5° (± 8.4°), on the AP view. The mean distance between the exit point of FT and the most distal end of the femoral condyles was 46.7 (± 4.9) mm. The mean FT length was 36.1 (± 3.1) mm. The mean difference of anterior translation compared to the intact knee was 1.9 (± 1.6) mm. Except the three patients, with "one positive" pivot shift test, in the remaining 35 knees stability was equal to the healthy knee.

CONCLUSIONS

Femoral drilling by using a femoral aimer device through AM portal provided long enough FT for safe graft fixation and appropriate coronal plan obliquity. The exit point was far proximal from the insertion site of the popliteus tendon and lateral collateral ligament. Furthermore, the AM portal technique significantly improved AP stability of the knee.

High incidence of partially anatomic tunnel placement in primary single-bundle ACL reconstruction

PURPOSE

The purpose of this study was to evaluate tunnel position and width in failed primary single-bundle (SB) anterior cruciate ligament (ACL) reconstructions. It was hypothesized that both femoral and tibial bone tunnels are frequently malplaced in terms of a partially anatomic position in the setting of failed SB ACL reconstruction.

METHODS

Patients with recurrent instability following isolated SB ACL reconstruction using hamstring tendon autografts, undergoing revision ACL surgery, were retrospectively included. Further inclusion criteria were age >18 years and availability of preoperative computed tomography (CT) scans and radiographs of the affected knee. Patients with multiligamentous instabilities as well as incomplete or poor radiographs were excluded. Tunnel position was evaluated according to the method described by Harner et al. and Stäubli and Rauschning. Tunnel width was determined on CT scans perpendicular to the bone tunnel axis at three different heights of each bone tunnel.

RESULTS

Eighty-two patients met the inclusion criteria and were considered for radiological analysis. Femoral tunnels were graded as anatomic in 60% (49 of 82) of all cases. In the remaining 40% (33/82), 27% of the tunnels were placed partially anatomic and 13% were graded as non-anatomic. Tibial tunnel placement was found to be anatomic in 54% (44/82) of all cases, partially anatomic in 45% and non-anatomic in 1% of the cases. No statistically significant difference between anatomic or partially anatomic tunnel position and tunnel diameter, neither for the femoral nor for the tibial side, was observed (n.s.).

CONCLUSION

The present study demonstrates that there is a high incidence of partially anatomic placed tunnels in failed SB ACL reconstruction. Tunnel width was not associated with tunnel position. Clinically, partially anatomic bone tunnels frequently require a staged procedure with bone grafting and subsequent ACL revision surgery. Thus, surgeons should carefully analyse tunnel position and width preoperatively to properly plan ACL revision surgery.

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

INTRODUCTION

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND

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

PURPOSE/HYPOTHESIS

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

STUDY DESIGN

Controlled laboratory study.

METHODS

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

RESULTS

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

CONCLUSION

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

CLINICAL RELEVANCE

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

Anatomy of the anterior cruciate ligament insertion sites: comparison of plain radiography and three-dimensional computed tomographic imaging to anatomic dissection

PURPOSE

The aim of this study was to provide quantitative data on insertion sites of anterior cruciate ligament (ACL) and to assess the correlation among measurements of anatomic dissection, plain radiographs, and 3D CT images to determine whether radiologic data can accurately reflect real anatomic measurements.

METHODS

Fifteen cadaveric knees were assessed using the three measurement modalities. Lengths of the long and short axis, area, and centre position of each bundle insertion sites by quadrant method were examined on both the femur and tibia. Distances from the insertion centre to distal cortical and posterior cortical margins of condyle on femur, and distance between insertion centres on tibia were also inspected.

RESULTS

The average ACL insertion position in the three measurement modalities was at 33.9 % in deep-shallow position and at 26.5 % in high-low position for anteromedial (AM) bundle and at 39.2 and 54.8 %, respectively, for posterolateral (PL) bundle in femur. For tibia, it was at 36.9 % in anterior-posterior position and 47.1 % in medial-lateral position for AM bundle and at 43.1 and 53.5 %, respectively, for PL bundle. The slight differences in various measurements among the three modalities were not statistically significant.

CONCLUSIONS

The femoral insertion positions were considerably shallow and low, whereas tibial insertion positions were near the average compared to those in previous studies. Plain radiographic and 3D CT measurements showed a reliable correlation with anatomic dissection measurements. The clinical relevance is that plain radiographs rather than 3D CT can be used as a post-operative evaluation tool after ACL reconstruction.

[Knee laxity in anterior cruciate ligament reconstruction : The influence of graft rotation using interference screw fixation]

BACKGROUND

The use of interference screws for femoral graft fixation in anterior cruciate ligament (ACL) reconstruction with hamstring grafts can result in rotation of the graft around the screw leading to changes in the final position of the graft within the bone tunnel.

MATERIAL AND METHODS

In a prospective study 107 patients (54 right and 53 left knees) underwent ACL reconstruction with a hamstring tendon autograft. Femoral fixation of the graft was performed with a standard right-thread screw in all cases. Patients were assessed at 6 months postoperatively with the international knee documentation committee (IKDC) standard evaluation including instrumented laxity measurements and the results were compared between right and left knees.

RESULTS

A significantly higher postoperative anterior laxity was observed in left knees with a negative Lachman test in only 64 % of the cases compared with 87 % in the group of right knees. Accordingly, instrumented laxity measurements of the reconstructed knee compared with the contralateral knee revealed significant differences between left and right knees (left knees 1.8±1.2 mm and right knees 1.0±1.4 mm).

CONCLUSIONS

This study demonstrates the importance of femoral graft positioning and its sensitivity to multiple influencing factors. The use of standard right-thread interference screws for femoral graft fixation in the mirrored situation of right and left knees may produce a systematic error in ACL reconstruction. Due to a possible rotation of the graft around the screw, the final position of the transplant may vary thus leading to significant changes in anterior translation of the operated knee.

Knee rotation influences the femoral tunnel angle measurement after anterior cruciate ligament reconstruction: a 3-dimensional computed tomography model study

PURPOSE

Femoral tunnel angle (FTA) has been proposed as a metric for evaluating whether ACL reconstruction was performed anatomically. In clinic, radiographic images are typically acquired with an uncertain amount of internal/external knee rotation. The extent to which knee rotation will influence FTA measurement is unclear. Furthermore, differences in FTA measurement between the two common positions (0° and 45° knee flexion) have not been established. The purpose of this study was to investigate the influence of knee rotation on FTA measurement after ACL reconstruction.

METHODS

Knee CT data from 16 subjects were segmented to produce 3D bone models. Central axes of tunnels were identified. The 0° and 45° flexion angles were simulated. Knee internal/external rotations were simulated in a range of ± 20°. FTA was defined as the angle between the tunnel axis and femoral shaft axis, orthogonally projected into the coronal plane.

RESULTS

Femoral tunnel angle was positively/negatively correlated with knee rotation angle at 0°/45° knee flexion. At 0° knee flexion, FTA for anterio-medial (AM) tunnels was significantly decreased at 20° of external knee rotation. At 45° knee flexion, more than 16° external or 19° internal rotation significantly altered FTA measurements for single-bundle tunnels; smaller rotations (± 9° for AM, ± 5° for PL) created significant errors in FTA measurements after double-bundle reconstruction.

CONCLUSION

Femoral tunnel angle measurements were correlated with knee rotation. Relatively small imaging malalignment introduced significant errors with knee flexed 45°. This study supports using the 0° flexion position for knee radiographs to reduce errors in FTA measurement due to knee internal/external rotation.

[Knee laxity in anterior cruciate ligament reconstruction. The influence of graft rotation using interference screw fixation]

BACKGROUND

The use of interference screws for femoral graft fixation in anterior cruciate ligament (ACL) reconstruction with hamstring grafts can result in rotation of the graft around the screw leading to changes in the final position of the graft within the bone tunnel.

MATERIAL AND METHODS

In a prospective study 107 patients (54 right and 53 left knees) underwent ACL reconstruction with a hamstring tendon autograft. Femoral fixation of the graft was performed with a standard right-thread screw in all cases. Patients were assessed at 6 months postoperatively with the international knee documentation committee (IKDC) standard evaluation including instrumented laxity measurements and the results were compared between right and left knees.

RESULTS

A significantly higher postoperative anterior laxity was observed in left knees with a negative Lachman test in only 64 % of the cases compared with 87 % in the group of right knees. Accordingly, instrumented laxity measurements of the reconstructed knee compared with the contralateral knee revealed significant differences between left and right knees (left knees 1.8±1.2 mm and right knees 1.0±1.4 mm)

CONCLUSIONS

This study demonstrates the importance of femoral graft positioning and its sensitivity to multiple influencing factors. The use of standard right-thread interference screws for femoral graft fixation in the mirrored situation of right and left knees may produce a systematic error in ACL reconstruction. Due to a possible rotation of the graft around the screw, the final position of the transplant may vary thus leading to significant changes in anterior translation of the operated knee.

Anteromedial portal versus transtibial drilling techniques in anterior cruciate ligament reconstruction: any clinical relevance? A retrospective comparative study

PURPOSE

This study aimed to undertake a retrospective analysis of prospectively collected data comparing, at a minimum follow-up of 5 years (78.1 ± 5.3 months v 75.6 ± 4.8 months), the clinical, functional, and radiographic outcomes of 2 homogeneous groups of athletes who had undergone arthroscopic single-bundle autologous hamstring reconstruction of the anterior cruciate ligament (ACL) using a transtibial (TT) or an anteromedial portal (AMP) approach to drill the femoral tunnel.

METHODS

Ninety-four patients were operated on in 2005 and 2006, and 88 (93.6%) (73 men, 15 women) were evaluated subjectively and objectively, using the Lysholm and International Knee Documentation Committee (IKDC) scores, manual maximum displacement test with a KT-1000 arthrometer (MEDmetric, San Diego, CA) and the Lachman test, and rotational instability with the pivot shift test. Degenerative changes were assessed on radiographs according to the Fairbank classification.

RESULTS

The median age at operation was 29 years (20 to 43 years; SD, 5.4) in the TT group 1 and 28 years (19 to 45 years; SD, 6.1) in the AMP group 2. At the last appointment, the 2 groups had similar results for the Lysholm and IKDC scores (primary outcome). Patients who underwent the AMP approach had less glide pivot shift (P = .42) and Lachman (P = .47) phenomena, with no statistically significant intergroup difference. Radiography showed fewer, but not significantly different, degenerative changes in the AMP ACL reconstruction group at final follow-up (P = .47).

CONCLUSIONS

In our series, ACL reconstruction using a femoral tunnel drilled through an AMP provided better rotational stability and anterior translation than drilling the femoral tunnel using the TT technique. This difference likely is not relevant from a clinical and functional viewpoint. The 2 groups of patients were not significantly different in terms of development of degenerative changes seen radiographically at a minimum follow-up of 5 years.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

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

INTRODUCTION

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

Level III, diagnostic study.