ACL Tunnel Research Articles

All‐soft tissue quadriceps tendon autograft and bone–patellar tendon–bone autograft demonstrate no significant ACL tunnel widening: An MRI comparison

All‐soft tissue quadriceps tendon autograft and bone–patellar tendon–bone autograft demonstrate no significant ACL tunnel widening: An MRI comparison

Grid and Image Intensifier Improve Arthroscopic ACL Tunnel Position and Patient-Reported Outcomes

To evaluate the accuracy in the femoral and tibial tunnel placement after the use of fluoroscopy along with an indigenously designed grid method to assist in arthroscopic anterior cruciate ligament reconstruction as compared with the tunnel placement without using them and to validate the findings with computed tomography scan performed postoperatively along with assessing the functional outcome at a minimum of 3 years of follow-up. This was a prospective study conducted on patients who underwent primary anterior cruciate ligament reconstruction. Patients were included and segregated into a nonfluoroscopy (group B) and a fluoroscopy group (group A), and both had postoperative computed tomography scans so that femoral and tibial tunnel position could be evaluated. Scheduled follow-up occurred 3, 6, 12, 24, and 36 months' postoperatively. Patients were evaluated objectively with the Lachman test, measurement of range of motion, and functional outcome using patient-reported outcome measures, i.e., Tegner Lysholm Knee score, Knee injury and Osteoarthritis Outcome Score, and International Knee Documentation Committee subjective knee score. A total of 113 subjects were included. There were 53 in group A and 60 in group B. The average location of femoral tunnel showed significant differences between the 2 groups. However, the variability in femoral tunnel location was significantly lower in group A as compared with group B for proximal-distal planes only. The average location of the tibial tunnel as per the grid of Bernard etal. showed significant differences in both the planes. The variability in tibial tunnel was greater in the medial-lateral plane as compared with the anterior-posterior plane. There was a statistically significant difference in mean value of the 3 scores among the 2 groups. The variability of the scores was greater in group B as compared with group A. None of the patient was reported as a failure. The results of our study suggests that fluoroscopy-guided positioning using a grid technique increases the accuracy of anterior cruciate ligament tunnel positioning with decreased variability and is associated with better patient-reported outcomes 3 years after surgery compared with tunnel positioning using landmarks. Level II, prospective, comparative therapeutic trial.

Poster 255: Lateral Extra-Articular Tenodesis Staple Risks Penetration of ACL Reconstruction Tunnel

Objectives:The purpose of this study was to identify the risk of ACL femoral tunnel penetration by a small Richards staple used for Lateral Extra-Articular Tenodesis (LET) fixation and to determine whether or not the risk varies between two techniques for ACL femoral tunnel creation.Methods:20 paired fresh frozen cadaver knees underwent ACL reconstruction with a LET using the modified Lemaire technique (Getgood et al. AJSM, Jan 2020). Left and right knees were randomized to ACL reconstruction with femoral tunnel creation by either the accessory anteromedial portal (AMP) technique or the flexible guide pin and reamer method. The femoral tunnels in the accessory AMP technique arm were created using a 7mm offset guide. Both arms used a 10mm reamer and were reamed to a depth of 25mm. After tunnel creation and prior to passing the ACL graft, the LET was performed. This was completed by harvesting an 8cm long and 10mm wide central portion of the IT band which was left attached to its distal insertion on Gerdy’s tubercle. This was routed underneath the LCL and fixed with a small Richards staple on the lateral metaphyseal flare proximal and posterior to the LCL insertion. The staple was angled anteriorly and distally. Fluoroscopy was used to obtain a lateral view of the knee to ensure appropriate position of the staple (Figure 1). Finally, tunneloscopy was performed from the anteromedial portal to investigate penetration of the staple into the femoral tunnel (Figure 2). A Fisher’s exact test was conducted to determine if there was any difference in tunnel penetration between tunnel creation techniques.Results:The staple was noted to penetrate the ACL femoral tunnel in 8/20 (40%) extremities. When stratified by tunnel creation technique, the Richards staple violated 5/10 (50%) of the tunnels made via the accessory AMP technique compared to 3/10 (30%) of those created with a flexible guide pin and reamer (p = 0.65).Conclusions:Staple fixation of a LET carries significant risk of penetrating the ACL tunnel that does not vary by the technique of femoral tunnel creation. This raises concerns over the potential effect of the staple on ACL graft fixation and the ACL graft itself.

Risk of femoral tunnel collision in combined and independent anterolateral and anterior cruciate ligament reconstruction with outside-in femoral drilling

Objectives:In combined ACL and anterolateral ligament (ALL) reconstruction with outside-in femoral drilling, there is a risk of femoral tunnel collision. The objective was to determine the optimal combination of ACL and ALL femoral tunnel orientation to minimize the risk of collision.Methods:Forty patients with isolated ACLR with inside-out femoral drilling were included. For each patient, a postoperative MRI of the femur was reconstructed in 3D. An ALL tunnel was modeled virtually with a pair of coronal and axial angles varying from 0° to 40°. The minimum distance to the existing ACL tunnel was measured for each pair of angles. For each patient, based on the optimal ALL orientation identified, a correlation between the ACL angle in relation to the axial plane and the distance between the ACL and the ALL tunnel was established.Results:The lowest collision rate between the ACL and ALL tunnels was measured at 0% with a 0° coronal and 40° anterior axial ALL fixation angle. In order to avoid the risk of femoral trochlea breaking when the ALL femoral tunnel is being created, it should not exceed 30 mm in length. In this context, the risk of trochlea breaking by the guide pin was evaluated at 42%. The closer the orientation of the ACL tunnel to the axis of the femoral shaft, the greater the distance to the ALL tunnel, which decreases the risk of collision of the 2 tunnels. A fixation system without guide wire should be used if trochlear breaking of the ALL guide pin is to be avoided.Conclusion:In a combined inside-out ACL and ALL reconstruction, we recommend creating the ALL tunnel with a 0° coronal and 40° axial fixation angle and the ACL tunnel with the orientation closest to the axis of the femoral shaft.

Tibial Tubercle Preserving Anterior Closing Wedge Proximal Tibial Osteotomy and ACL Tunnel Bone Grafting for Increased Posterior Tibial Slope in Failed ACL Reconstructions

Anterior cruciate ligament reconstruction (ACLR) failure is multifactorial, but it is known that increased posterior tibial slope (PTS) leads to a greater likelihood of ACLR failure. This technical note describes the senior author’s technique for performing an anterior closing wedge proximal tibial osteotomy, in which the osteotomy is made proximal to the tibial tubercle. This procedure is the first part of a staged surgery for patients with multiple failed ACLRs and increased sagittal plane PTS. Debridement of osteolytic reconstruction tunnels with bone grafting is also undertaken in preparation for a second-stage revision ACLR.

Tibial Slope Correction as an Infratuberosity Closing-Wedge Extension Osteotomy in ACL-Deficient Knees.

ACL insufficiency can be caused by different reasons. Elevated posterior tibial slope is a deformity which is discussed to have relevant influence on the outcome of ACL surgery. A increased posterior tibial slope of 12° or more leads to significant more ACL insufficiency. The surgical therapy of this pathology is a high tibial extension osteotomy. Publications ashowing a clinical follow up and results of this surgery are rare. In this video the technique of a closed wedge high tibial extension osteotomy is shown. Osteosynthesis is performed with two screws and an anklestable plate osteosynthesis. An arthroscopy with bone graft filling of the femoral ACL tunnel is performed first, followed by filling of the tibial tunnel in an open approach.

The location of the femoral ACL footprint center is different depending on the Blumensaat's line morphology.

The purpose of this study was to evaluate the difference in the center point of the femoral ACL footprint according to the morphological variations of the Blumensaat's line. Fifty-nine non-paired human cadaver knees were used. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch. Digital images were evaluated using the Image J software. The periphery of the femoral ACL footprint was outlined and the center point was measured automatically. Following Iriuchishima's classification, the morphology of the Blumensaat's line was classified into straight and hill types (small and large hill types). The center of the femoral ACL footprint and hilltop placement were evaluated using the quadrant method. A quadrant grid was placed uniformly, irregardless of hill existence, and not including the articular cartilage. A correlation analysis was performed between the center point of the femoral ACL footprint and hilltop placement. The straight type consisted of 19 knees, and the hill type 40 knees (small hill type 13 knees and large hill type 27 knees). The center of the femoral ACL footprint (shallow-deep/high-low) in the straight and hill type knees was 33.7/47.6%, and 37.2/50.3%, respectively. In the hill type, the ACL footprint center was significantly more shallow when compared to the straight type. Significant correlation was observed between the center point of the femoral ACL footprint and hilltop placement of the Blumensaat's line. The center point of the femoral ACL footprint was significantly more shallow in the hill type knees when compared to the straight type. For clinical relevance, considering that the location of the femoral ACL footprint center is different depending on the Blumensaat's line morphology, to perform accurate ACL reconstruction, femoral ACL tunnel placement should be made based on Blumensaat's line morphological variations.

High incidence of tunnel collision in combined ACL reconstruction and LET

Aims and Objectives:Lateral extra-articular tenodesis (LET) procedures are being increasingly performed as concomitant procedures to both primary and revision intra-articular ACL reconstructions with the purpose of controlling excessive anterolateral rotatory instability and to reduce tension on the ACL graft.There is, however, a lack of evidence on benefits and pitfalls of different femoral LET attachment positions.The purpose of this study was to assess the risk of tunnel convergence in combined ACL and LET procedures comparing two different femoral attachment sites (Lemaire and MacIntosh).Materials and Methods:10 fresh-frozen cadaver knees were examined. In each specimen an anatomic ACL femoral tunnel and two LET tunnels were drilled applying the Lemaire and MacIntosh position. Following knee dissection, minimal distances between ACL and LET tunnels were directly measured on the lateral femoral cortex. Furthermore, computed tomography (CT) scans were obtained to measure inter-tunnel convergence and lateral femoral condyle (LFC) width. Based on the average LFC width, knees were divided into large and small knees to determine a relationship between knee size and tunnel convergence.Results:Convergence of ACL and LET tunnels occurred in 7 of 10 cases (70%) using the Lemaire attachment position. All tunnel collisions occurred directly on the lateral femoral cortex, while inter-tunnel conflicts were not observed. Collisions emerged in both, small (n=4) and large (n=3) knees. Critical tunnel convergence did not occur using the MacIntosh position. The mean minimal distance between the LET and ACL tunnel using the Lemaire and MacIntosh position was 3.1±4.6 mm and 9.8±5.4 mm, respectively.Conclusion:A high risk of tunnel convergence was observed in combined ACL and LET reconstruction using the Lemaire technique, independent of the knee size. LET femoral tunnel positioning according to the MacIntosh reconstruction can significantly reduce the risk of tunnel collision. These findings help to intraoperatively raise the awareness for the risk of tunnel convergence in combined ACL and LET procedures.Adjustments on ACL reconstruction techniques and especially on the femoral fixation have to be considered when applying an additional Lemaire reconstruction.

Quantitative MRI Evaluation of Tunnel placement in ACL Reconstruction

Introduction:Positioning of the graft ACL in the native footprint center is important to replicate the anatomy and function of the ACL for each individual patient. It is known that incorrect bone tunnel placement for the reconstructed ligament is a contributor to poor clinical outcomes postoperatively. Currently the success of tunnel placement is determined by training and experience of the treating surgeon and there is no universally accepted quantifiable and objective method to evaluate the execution of these decisions. The goal of this project was to develop a quantitative routine assessment to assist pre-surgical planning and also evaluate the execution of femoral and tibial bone tunnel placement in ACL reconstructed knees.Methods:The study recruited failed primary ACL reconstructed patients (N=25) who consented to undergo revision ACL reconstruction to establish the placement of the graft ACL tunnel apertures in the femur and tibia. Prior to surgery each participant underwent high resolution 3 T MRI of their injured knee and 3D models were generated through segmentation of soft and hard tissue knee structures. During surgery previous graft tunnels and prominent reference landmarks visible on MRI and arthroscopically were registered using intraoperative navigation to act as the reference standard. The placement of the tunnel apertures in the femur and tibia were measured in all three planes using a novel measurement method.Results:Preliminary result show that the measurement method can assess the placement of tunnel apertures in the femur and tibia within 0.1 – 1.0 mm of the intraoperative data, using reference landmarks identifiable in MRI and arthroscopically. Additionally, the area of the tunnel aperture, bone tunnel volume can be evaluated. Reliability and validation of the novel method is ongoing using medical imaging and intraoperative navigation to register the placement of bone tunnels in revision ACL reconstruction patients.Conclusions:Correct placement of graft ACL bone tunnels inside the native ACL footprint is critical to the outcome of ACL reconstruction. Development of an accurate reproducible method for assessment of tunnel placement relative to the anatomical footprint should provide a simple method for objectively assessing ACL reconstructions. Preliminary results of this routine assessment suggests that graft tunnel placement can be objectively assessed to assist clinicians to evaluate and improve ACL reconstruction technique and evaluation of ACL reconstruction outcomes.

Radiographic positions of femoral ACL, AM and PL centres: accuracy of guidelines based on the lateral quadrant method.

Femoral tunnel positioning is an important factor in anatomical ACL reconstructions. To improve accuracy, lateral radiographic support can be used to determine the correct tunnel location, applying the quadrant method. Piefer et al. (Arthroscopy 28:872-881, 2012) combined various outcomes of eight studies applying this method to one guideline. The studies included in that guideline used various insertion margins, imaging techniques and measurement methods to determine the position of the ACL centres. The question we addressed is whether condensing data from various methods into one guideline, results in a more accurate guideline than the results of one study. The accuracy of the Piefer's guideline was determined and compared to a guideline developed by Luites et al. (2000). For both guidelines, we quantified the mean absolute differences in positions of the actual anatomical centres of the ACL, AM and PL measured on the lateral radiographs of twelve femora with the quadrant method and the positions according to the guidelines. The accuracy of Piefer's guidelines was 2.4mm (ACL), 2.7mm (AM) and 4.6mm (PL), resulting in positions significantly different from the actual anatomical centres. Applying Luites' guidelines for ACL and PL resulted in positions not significantly different from the actual centres. The accuracies were 1.6mm (ACL) and 2.2mm (PL and AM), which were significantly different from Piefer for the PL centres, and therefore more accurate. Condensing the outcomes of multiple studies using various insertion margins, imaging techniques and measurement methods, results in inaccurate guidelines for femoral ACL tunnel positioning at the lateral view. An accurate femoral tunnel positioning for anatomical ACL reconstruction is a key issue. The results of this study demonstrate that averaging of various radiographic guidelines for anatomical femoral ACL tunnel placement in daily practice, can result in inaccurate tunnel positions. Diagnostic study, Level 1.

A systematic review of single- versus double-bundle ACL reconstruction using the anatomic anterior cruciate ligament reconstruction scoring checklist.

The aim of this systematic review was to apply the anatomic ACL reconstruction scoring checklist (AARSC) and to evaluate the degree to which clinical studies comparing single-bundle (SB) and double-bundle (DB) ACL reconstructions are anatomic. A systematic electronic search was performed using the databases PubMed (MEDLINE), EMBASE and Cochrane Library. Studies published from January 1995 to January 2014 comparing SB and DB ACL reconstructions with clinical outcome measurements were included. The items from the AARSC were recorded for both the SB and DB groups in each study. Eight-thousand nine-hundred and ninety-four studies were analysed, 77 were included. Randomized clinical trials (29; 38%) and prospective comparative studies (29; 38%) were the most frequent study type. Most studies were published in 2011 (19; 25%). The most commonly reported items for both SB and DB groups were as follows: graft type (152; 99%), femoral and tibial fixation method (149; 97% respectively), knee flexion angle during graft tensioning (124; 8%) and placement of the tibial tunnel at the ACL insertion site (101; 66%). The highest level of documentation used for ACL tunnel position for both groups was often one dimensional, e.g. drawing, operative notes or o'clock reference. The DB reconstruction was in general more thoroughly reported. The means for the AARSC were 6.9 ± 2.8 for the SB group and 8.3 ± 2.8 for the DB group. Both means were below a proposed required minimum score of 10 for anatomic ACL reconstruction. There was substantial underreporting of surgical data for both the SB and DB groups in clinical studies. This underreporting creates difficulties when analysing, comparing and pooling results of scientific studies on this subject.

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

BackgroundAnterior 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. MethodsSeventy-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. ResultsAfter 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. ConclusionCT 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.

Surgically oriented measurements for three-dimensional characterization of tunnel placement in anterior cruciate ligament reconstruction

Objective: To develop and evaluate the feasibility and reliability of an alternative three-dimensional (3D) measurement system capable of characterizing tunnel position and orientation in ACL reconstructed knees.Methods: We developed a surgically oriented 3D measurement system for characterizing femoral and tibial drill tunnels from ACL reconstructions. This is accomplished by simulating the positioning of the drill bit originally used to create the tunnels within the bone, which allows for angular and spatial descriptions along defined axes that are established with respect to previously described anatomic landmarks and radiographic views. Computer-generated digital phantoms composed of simplified geometries were used to verify proper calculation of angular and spatial measurements. We also evaluated the inter-observer reliability of the measurements using 10 surfaces generated from cadaveric knees in which ACL tunnels were drilled. The reliability of the measurements was evaluated by intraclass correlation coefficients.Results: The digital phantom evaluation verified the measurement methods by computing angular and spatial values that matched the known values in all cases. The intraclass correlation coefficient was calculated for four users and was found to range from 0.95 to 0.99 for the femoral and tibial measurements, demonstrating near-perfect agreement.Conclusions: The characterization of ACL tunnels has historically concentrated on two-dimensional (2D) measurements; however, it can be difficult to define ACL tunnel placement using 2D methods. We have presented novel techniques for defining graft tunnel placement from 3D surface representations of the ACL reconstructed knee. These measurements provide exact tunnel location spatially and along axes that offer the potential to comparatively analyze ACL reconstructions post-operatively using advanced imaging. These methods are reliable, and have been demonstrated to be applicable to multiple single-bundle techniques for ACL reconstruction.

The effects of limb alignment on anterior cruciate ligament graft tunnel positions estimated from plain radiographs

The aims of this study were (1) to evaluate the femoral tunnel position after anatomic double-bundle and nonanatomic single-bundle reconstruction; (2) to evaluate the influence of rotation of the femur caused by limb malalignment on measurements of the position of the femoral ACL tunnel aperture relative to Blumensaat's line. 3D CT scans were performed in 5 patients after anatomic double-bundle reconstruction and 5 patients after nonanatomic single-bundle reconstruction. Digitally reconstructed lateral radiographs were generated from the 3D CT scans to determine the tunnel position on the femur along and perpendicular to Blumensaat's line. The femur was then rotated to simulate internal/external and varus/valgus rotations from 0° to 15° in 5° increments. At each rotated bone position, tunnel position relative to Blumensaat's line was calculated and the difference from the lateral radiograph was calculated. After double-bundle reconstruction, the AM tunnel was located at 31.5 (±5.0) % along Blumensaat's line and 29.7 (±13.6) % perpendicular to Blumensaat's line, and the PL tunnel at 36.2 (±12.9) % along Blumensaat's line and 34.2 (±7.6) % perpendicular to Blumensaat's line. Valgus greater than 10° significantly affected the assessment of tunnel position (P = 0.043). After nonanatomic single-bundle reconstruction, the tunnel position was 35.4 (±15.0) % along Blumensaat's line and -2.7 (±19.4) % perpendicular to Blumensaat's line. Internal rotation of more than 10° significantly affected the assessment of tunnel position (P = 0.043). Tunnel position after anatomic double-bundle reconstruction and nonanatomic single-bundle reconstruction can be determined on lateral radiographs. However, valgus and internal rotation of more than 10° can introduce significant errors in tunnel position estimates. Case series, Level IV.

Anatomic Landmarks Utilized for Physeal-Sparing, Anatomic Anterior Cruciate Ligament Reconstruction: An MRI-Based Study (SS-68)

<h3>Introduction</h3> ACL injury and reconstruction are becoming more common in the skeletally immature. Damage to the femoral physes and concomitant growth disturbance is a fear for the surgeon, patient, and family. The use of an all-epiphyseal technique on the femoral side is gaining popularity, but is technically difficult, requires intraoperative X-ray, leads to variable femoral tunnel locations and is non-anatomic as currently described. The purpose of the study was to develop an easily reproducible, anatomic reconstructive technique using intra- and extra-articular landmarks, which can reliably produce a femoral tunnel of adequate length and diameter, while at the same time avoiding the femoral physis. <h3>Methods</h3> 188 MRI studies were evaluated for children aged 6 to 17. Multiple anatomic landmarks were examined to determine optimal landmarks for ACL reconstruction (reproducibility, physeal safety, ease of identification, etc.). The extra-articular landmarks were the femoral origin of the popliteus tendon and the lateral epicondyle. The intra-articular landmark was the central portion of the femoral ACL origin. Using multi-plane computer software, points were plotted at the three landmarks in all three planes. Lines, depicting potential femoral tunnels were then drawn connecting the ACL origin to the popliteal insertion and the lateral epicondyle. Distances were then calculated for lengths of these tunnels, the shortest distance from the physis to these tunnels, the width of the femoral notch, and the width and height of the femoral condyles. Statistical analysis was then performed, comparing distances between age groups and sexes. 3D MRI Physeal-reconstruction employed, confirmed that the chosen landmarks spared the physes after tunnel placement. <h3>Results</h3> Tunnel lengths from the ACL origin to the popliteus insertion, tunnel lengths from the ACL origin to the lateral epicondyle, total femoral widths, and notch widths significantly differed across all age groups and sexes (p<0.001), as did condylar heights (p<0.03). Average distance to the femoral physis from the tunnel, which was from the ACL origin to the popliteus were 12 mm, independent of sex or age (p<0.94), and the shortest distance was 8 mm. This tunnel length averaged 30.1 mm in males and 27.4 mm in females (p<0.001), with an average of 25.6 mm in 6-year-olds and 30.2 mm in 17-year-olds. Average distance to the femoral physis from the tunnel, which was from the ACL origin to the lateral epicondyle were 8.8 mm in males and 8.9 mm in females (p<0.55), and this tunnel's average length was 34.3 mm in males and 31.6 mm in females (p<0.001). <h3>Conclusion</h3> Advantages to sparing the femoral physis when drilling the femoral ACL tunnel are obvious, however the biomechanical advantages of anatomic ACL reconstruction are still being studied. A combination of the two techniques may be the preferred technique for skeletally immature patients in the future. Drilling from the ACL origin to the popliteal insertion will produce an average tunnel length of 27-30 mm for graft incorporation and safely allow at least an 8-10 mm diameter tunnel in a patient 6 to 17 years old. Using the easily identifiable landmarks discussed in this paper will allow safe, reproducible anatomic ACL reconstructions without the need for tedious x-ray utilization intra-operatively.

Precision of ACL Tunnel Placement Using Traditional and Robotic Techniques

The objective of this study was to examine the precision of ACL tunnel placement using: (1) Caspar® (orto MAQUET GmbH Co. KG) an active robotic system, and (2) four orthopedic surgeons with various levels of experience (between 100 and 3,500 ACL reconstructions). The robotic system and each surgeon drilled tunnels for ACL reconstruction in 10 plastic knees (total n = 50) that included a reference cube in the medial aspect of the proximal tibia and distal femur. For the robotic system, the placement of each tunnel was planned preoperatively using custom software and CT data for each femur and tibia. The robotic system then drilled the tunnels in the femur and tibia based on the preoperative plan. For the surgeons, tunnel placement was accomplished using their preferred technique, which was based on the one-incision arthroscopic technique. The distribution of intra-articular points on the tibia was contained within a sphere of radius 2.0 mm (robot system), 2.1 mm (Fellow 1), 2.4 mm (Fellow 2), 3.4 mm (Experienced Surgeon 1), or 2.0 mm (Experienced Surgeon 2). On the femur, no significant differences in the distribution of intra-articular points could be demonstrated between the robotic system (2.1 mm), Fellow 1 (4.5 mm), Fellow 2 (4.1 mm), Experienced Surgeon 1 (2.3 mm), and Experienced Surgeon 2 (3.0 mm). The direction of the tunnels drilled in the femur and tibia was different with the robotic and traditional techniques. However, the robotic system had the most consistent tunnel directions, while the surgeons tunnels were more dispersed. Variation in surgeon precision of tunnel placement for ACL reconstruction is greater on the femur than the tibia, and this can be correlated with experience. Our data also suggest that the robotic system has the same precision as the most experienced surgeons.