Femoral tunnel reaming method in anterior cruciate ligament reconstruction cannot be determined from plain radiographs alone

Anatomic placement of the femoral tunnel is critical to the success and clinical outcome of anterior cruciate ligament (ACL) reconstruction [1–11]. Anatomic single-bundle ACL reconstruction is defined as a single-bundle ACL reconstruction in which the femoral and tibial bone tunnels are positioned at the center of the native ACL femoral and tibial attachment sites [1, 3, 12, 13]. Nonanatomic ACL tunnel placement is the most common technical error leading to recurrent instability and a failed ACL reconstruction [2, 4–7, 9–11]. Proper placement of the ACL femoral tunnel is especially important because the length and tension of the ACL replacement graft is most influenced by the position of the ACL femoral tunnel [14–18]. Malposition of the ACL femoral tunnel can cause excessive tightening or loosening of the ACL graft, which may result in a loss of motion and or patholaxity of the knee [2, 4–11, 15–18]. Proper placement of the femoral tunnel during ACL reconstruction is therefore a critical part of the surgical procedure. A working knowledge of the anatomy of the ACL femoral attachment site is important to ensure anatomic placement of the ACL femoral tunnel. The anatomy of the ACL has been discussed in greater detail elsewhere in this book. To summarize, the ACL femoral attachment site is oval in appearance and is located along the lower third of the inner wall of the lateral femoral condyle [13, 14, 19–26]. The ACL femoral attachment site is defined by two bony ridges, the lateral intercondylar and the lateral bifurcate ridges [13, 20, 22–24, 26, 27] (Fig. 19.1). The lateral intercondylar ridge is an important anatomic landmark since the native ACL always attaches inferior (arthroscopic description) or posterior (anatomic description) to the lateral intercondylar ridge [3, 20, 22–24, 26–28] (Fig. 19.1). The lateral intercondylar ridge can be identified arthroscopically in 88 % of subacute and chronic ACL-deficient knees and therefore is a consistent anatomic landmark to assist the knee surgeon with placement of the ACL femoral tunnel [29]. The lateral bifurcate ridge which can be identified arthroscopically in 48 % of subacute and chronic knees runs perpendicular to the lateral intercondylar ridge and divides the ACL femoral attachment site into the attachment site areas for the posterolateral (PL) and anteromedial (AM) bundles [3, 12, 13, 20, 22, 24, 26] (Fig. 19.1). The center of the ACL femoral attachment site is 1.7 mm deep or proximal to the bifurcate ridge and 7.3–8.5 mm superior or anterior to the inferior or posterior articular cartilage margin of the lateral femoral condyle [8, 21, 23, 28]. For anatomic single-bundle ACL reconstruction, the center of the ACL femoral attachment site is chosen as the position for the ACL femoral tunnel [1, 3, 5, 12, 13, 30–32]. Biomechanical and clinical studies have demonstrated that ACL reconstruction using a replacement graft placed at the center of the ACL femoral and tibial attachment sites is more effective at controlling anterior tibial translation and the combined motions of anterior tibial translation and internal tibial rotation (simulated pivot shift test) and restores knee kinematics more closely to that of the normal knee compared to “isometric” ACL femoral tunnel placement, other anatomic ACL tunnel placements, or techniques that have traditionally restored predominantly the AM bundle fibers [1, 6, 30–38].

Accurate placement of the femoral tunnel is critical for long-term clinical success following anterior cruciate ligament (ACL) reconstruction. The purpose of the present study is to evaluate the accuracy of femoral tunnel placement when referencing osseous landmarks during ACL reconstruction. We hypothesize that referencing osseous landmarks during ACL reconstruction consistently results in anatomic placement of the ACL femoral tunnel. This study was a retrospective case series. We reviewed 83 consecutive ACL reconstructions performed by a single surgeon. The lateral intercondylar ridge and lateral bifurcate ridge were referenced intraoperatively for anatomic placement of the ACL femoral tunnel during single-bundle reconstruction. Using these landmarks, the femoral tunnel was placed in the center of the anteromedial bundle footprint on the lateral wall of the intercondylar notch. We reviewed all operative notes and intraoperative arthroscopic images to assess tunnel placement. Postoperative anteroposterior and lateral radiographs were obtained in all patients. Anatomic placement was confirmed by review of lateral radiographs utilizing both the quadrant method (QM) and Blumensaat-ridge ratio (BRR). We used a total of 80 patients for our study. Review of arthroscopic images confirmed anatomic placement of the ACL femoral tunnel in all patients. All patients demonstrated that the femoral tunnel was placed anatomically according to the BRR method. Using the QM, all femoral tunnels were placed anatomically except for one tunnel that was placed slightly anteriorly. There was excellent agreement between the two radiographic measurement techniques. The principal finding of this study indicates that the lateral intercondylar ridge and the lateral bifurcate ridge are reliable landmarks for anatomic placement of the ACL femoral tunnel. Referencing osseous landmarks during surgery can help surgeons avoid nonanatomic placement of the ACL femoral tunnel, especially in cases where the soft-tissue footprint is no longer present. Furthermore, both the radiographic QM and the BRR are valid techniques to assess for anatomic ACL femoral tunnel placement both intraoperatively and postoperatively.

The purpose of this study was to identify risk factors for subsequent meniscal surgery following anterior cruciate ligament (ACL) reconstruction (ACLR) in patients without recurrent ACL injury. Patients aged ≥14 years who underwent primary ACLR with minimum 1-year follow-up and without recurrent ACL injury were retrospectively reviewed. Patient demographics and surgical data at the time of ACLR were collected. Postoperative radiographs were used to measure femoral and tibial tunnel position, and posterior tibial slope. Univariate and multivariate analyses were performed to identify risk factors for subsequent meniscal surgery. Of 629 ACLRs that fulfilled the inclusion criteria, subsequent meniscal surgery was performed in 65 [10.3%] patients. Multivariate analysis revealed that medial meniscal repair at the time of ACLR, younger age, anterior femoral tunnel position and distal femoral tunnel position were significantly associated with subsequent meniscal surgery (p < 0.001, p = 0.016, p = 0.015, p = 0.035, respectively). The frequency of femoral tunnel placement >10% outside of the literature-established anatomic position was significantly higher in those who underwent subsequent meniscal surgery compared to those who did not (38.3% vs. 20.3%, p = 0.006). Posterior tibial slope and ACL graft type were not significantly associated with subsequent meniscal surgery. Medial meniscal repair at the time of ACLR, younger age and nonanatomic femoral tunnel placement were risk factors for subsequent meniscal surgery in patients without recurrent ACL injury. Femoral tunnel placement <10% outside of the native anatomic position is important to reduce the risk of subsequent meniscal surgery. Level IV.

Background: Anterior cruciate ligament (ACL) reconstruction failure occurs in up to 10% of cases. Technical errors are considered the most common cause of graft failure despite the absence of validated studies. Limited data are available regarding the agreement among orthopaedic surgeons regarding the causes of primary ACL reconstruction failure and accuracy of graft tunnel placement. Hypothesis: Experienced knee surgeons have a high level of interobserver reliability in the agreement about the causes of primary ACL reconstruction failure, anatomic graft characteristics, and tunnel placement. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: Twenty cases of revision ACL reconstruction were randomly selected from the Multicenter ACL Revision Study (MARS) database. Each case included the patient’s history, standardized radiographs, and a concise 30-second arthroscopic video taken at the time of revision demonstrating the graft remnant and location of the tunnel apertures. All 20 cases were reviewed by 10 MARS surgeons not involved with the primary surgery. Each surgeon completed a 2-part questionnaire dealing with each surgeon’s training and practice, as well as the placement of the femoral and tibial tunnels, condition of the primary graft, and the surgeon’s opinion as to the causes of graft failure. Interrater agreement was determined for each question with the kappa coefficient and the prevalence-adjusted, bias-adjusted kappa (PABAK). Results: The 10 reviewers have been in practice an average of 14 years and have performed at least 25 ACL reconstructions per year, and 9 were fellowship trained in sports medicine. There was wide variability in agreement among knee experts as to the specific causes of ACL graft failure. When participants were specifically asked about technical error as the cause for failure, interobserver agreement was only slight (PABAK = 0.26). There was fair overall agreement on ideal femoral tunnel placement (PABAK = 0.55) but only slight agreement on whether a femoral tunnel was too anterior (PABAK = 0.24) and fair agreement on whether it was too vertical (PABAK = 0.46). There was poor overall agreement for ideal tibial tunnel placement (PABAK = 0.17). Conclusion: This study suggests that more objective criteria are needed to accurately determine the causes of primary ACL graft failure as well as the ideal femoral and tibial tunnel placement in patients undergoing revision ACL reconstruction.

Author's Reply

Objectives: Femoral tunnel placement is a critical step in ACL reconstruction surgery. Surgeons usually end up clearing the soft tissue to access the bony landmarks. Biological ACL reconstruction with preservation of soft tissue can be done with reliable soft tissue landmarks. Our objective is to assess the reliability of a soft tissue landmark- femoral ACL remnant, for appropriate femoral tunnel placement in soft tissue preserving ACL reconstruction. Materials and Methods: This study was a retrospective analysis of prospectively collected data of 40 consecutive patients who underwent primary ACL reconstruction in January 2018 by a single surgeon. An inverse J shaped tissue arch was identified and used as soft tissue landmark for anatomic placement of femoral tunnel. This arch was a part of femoral ACL remnant. MRI films were examined post-operatively to determine the position of the femoral tunnel. Postoperatively, MRI of these patients were reviewed to evaluate the femoral tunnel position in terms of depth and height from the proximal condylar surface and notch roof, respectively. Results: The center of the femoral tunnel was found to be at a mean depth of 27.12 ± 2.2% from the proximal condylar surface (parallel to Blumensaat’s line) and a mean height of 30.96 ± 2.75% from the notch roof (perpendicular to Blumensaat’s line), which is at par with previously defined data given by various studies. Conclusion: J arch can be used as a dependable soft tissue landmark and a guide for the anatomic placement of femoral tunnel in biological ACL Reconstruction.

The purpose of this study was to investigate the correlation between femoral intercondylar notch volume and the characteristics of femoral tunnels in anatomical single bundle anterior cruciate ligament (ACL) reconstruction. Fifty-one subjects (24 male and 27 female: median age 27: range 15-49), were included in this study. Anatomical single bundle ACL reconstruction was performed in all subjects using a trans-portal technique. Femoral tunnel length was measured intra-operatively. Three-dimensional computed tomography (3D-CT) was taken at pre and post-surgery. The intercondylar notch volume was calculated with a truncated-pyramid shape simulation using the pre-operative 3D-CT image. In the post-operative 3D-CT, the modified quadrant method was used to measure femoral ACL tunnel placement. Femoral tunnel placement was 47.6 ± 10.5% in the high-low (proximal-distal) direction, and 22.6 ± 5.4% in the shallow-deep (anterior-posterior) direction. Femoral tunnel length was 35.3 ± 4.4cm. Femoral intercondylar notch volume was 8.6 ± 2.1cm3. A significant correlation was found between femoral intercondylar notch volume and high-low (proximal-distal) femoral tunnel placement (Pearson's coefficient correlation: 0.469, p = 0.003). Femoral ACL tunnel placement at a significantly lower level was found in knees with large femoral intercondylar notch volume in the trans-portal technique. For the clinical relevance, although the sample size of this study was limited, surgeons can create femoral ACL tunnel low (distal) in the notch where close to the anatomical ACL footprint in the knees with large femoral intercondylar notch volume. III.

Background:Accurate tibial and femoral tunnel placement has a significant effect on outcomes after anterior cruciate ligament reconstruction (ACLR). Postoperative radiographs provide a reliable and valid way for the assessment of anatomical tunnel placement after ACLR. The aim of this study was to examine the radiographic location of tibial and femoral tunnels in patients who underwent arthroscopic ACLR using anatomic landmarks. Patients who underwent arthroscopic ACLR from January 2014 to March 2016 were included in this retrospective cohort study.Materials and Methods:45 patients who underwent arthroscopic ACLR, postoperative radiographs were studied. Femoral and tibial tunnel positions on sagittal and coronal radiographic views, graft impingement, and femoral roof angle were measured. Radiological parameters were summarized as mean ± standard deviation and proportions as applicable. Interobserver agreement was measured using intraclass correlation coefficient.Results:The position of the tibial tunnel was found to be at an average of 35.1% ± 7.4% posterior from the anterior edge of the tibia. The femoral tunnel was found at an average of 30% ± 1% anterior to the posterior femoral cortex along the Blumensaat's line. Radiographic impingement was found in 34% of the patients. The roof angle averaged 34.3° ± 4.3°. The position of the tibial tunnel was found at an average of 44.16% ± 3.98% from the medial edge of the tibial plateau. The coronal tibial tunnel angle averaged 67.5° ± 8.9°. The coronal angle of the femoral tunnel averaged 41.9° ± 8.5°.Conclusions:The femoral and tibial tunnel placements correlated well with anatomic landmarks except for radiographic impingement which was present in 34% of the patients.

The purpose of this study was to compare femoral tunnel geometry including tunnel position, length, and graft bending angle between trans-portal and outside-in techniques in anterior cruciate ligament (ACL) reconstruction and discover whether such differences in tunnel geometry could influence graft healing or clinical outcome. Sixty-four patients with anatomical single-bundle ACL reconstruction performed with either trans-portal technique (32 patients, one centre) or outside-in technique (32 patients, the other centre) were included in this retrospective study. Femoral tunnel location and length, and graft bending angle at the femoral tunnel were analysed on 3D CT knee model. The location and length of the femoral tunnel and graft bending angle were compared between the two techniques. All patients underwent MRI scans at around 1year following ACL reconstruction. It was found that all patients had intact ACL graft on MRI images. On oblique axial image taken after ACL reconstruction to determine graft healing at femoral and tibial tunnels and the intra-articular portion, graft signal intensity ratio was calculated by dividing signal intensity (SI) of the reconstructed ACL by that of posterior cruciate ligament (PCL) in the region of interest selected with Marosis software. Clinical outcomes regarding Tegner activity scores, the International Knee Documentation Committee (IKDC) evaluation scores, Lachman test, and pivot shift test results were also compared between the two groups. While the location of femoral tunnel was similar to each other in both groups, the femoral tunnel length was longer in the outside-in technique (37.0 vs. 32.4mm, p=.02). Meanwhile, the outside-in technique showed significantly more acute graft tunnel angle than the trans-portal technique (106.7° vs. 113.8°, p=.01). However, signal intensity ratios of grafts (compared with SI of PCL) were similar in femoral and tibial tunnels and intra-articular portions. Moreover, there were no statistically significant differences in terms of IKDC scores (89.4 vs. 90.5, n.s.) or Tegner activity scores (6.2 vs. 6.4, n.s.) between the two groups. There was no significant difference in measurement of Lachman or Pivot shift test either between the two groups. Even though the outside-in technique in ACL reconstruction created a more acute femoral graft bending angle and a longer femoral tunnel length than the trans-portal technique, these had no negative effect on graft healing. In addition, trans-portal and outside-in techniques in ACL reconstruction showed similar femoral tunnel positions and clinical outcomes. Acceptable graft healing and clinical outcomes can be obtained for both trans-portal and outside-in techniques in ACL reconstruction. III.

Introduction: Anterior cruciate ligament (ACL) tear is the most common knee ligament injury. Postoperative radiological evaluation after ACL reconstruction is essential to assess the femoral and tibial tunnels. Proper placement of these tunnels significantly impacts the outcomes of ACL reconstruction. This case report reviews the anatomical positioning of the femoral and tibial tunnels using conventional radiography, computed tomography (CT) scan, and magnetic resonance imaging (MRI). Case Descriptions: We reported 3 cases after single-bundle ACL reconstruction. The patients came with diagnosis of ACL tear. After underwent ACL reconstruction, they took postoperative radiological evaluation. The first patient was evaluated using conventional radiography, measuring the femoral and tibial angles and the position of the femoral and tibial tunnel. The second patient underwent CT-scan to evaluate the position of the femoral and tibial tunnel and the width of the tunnel. The third patient was evaluated for postoperative ACL reconstruction using MRI after 6 months postoperatively. We assessed the general healing process, graft integrity, tunnel position, and tunnel enlargement. Discussion: ACL reconstruction aims to establish an isometric, anatomical, and impingement-free graft. In cases of technical failure, 80% are attributed to femoral tunnel malposition, which determines graft isometry, the constancy in length, and tension of the graft throughout knee motion. Tibial tunnel positioning is crucial to prevent ACL graft impingement. Conclusion: Radiologists must understand proper femoral and tibial tunnel placement to avoid reconstruction failure. Conventional radiography serves as a practical initial tool for postoperative evaluation. Latar Belakang: Robekan pada Anterior CruciateLligament (ACL) adalah cedera ligamen lutut yang paling umum. Evaluasi radiologi pasca operasi rekonstruksi ACL diperlukan untuk mengevaluasi tunnel femoralis dan tibialis. Penempatan tunnel femoral dan tibialis yang akurat memiliki pengaruh yang signifikan terhadap hasil setelah rekonstruksi ACL. Laporan kasus ini meninjau posisi anatomi tunnel femoral dan tibialis menggunakan radiografi konvensional, computerized tomography (CT)-scan dan magnetic resonance imaging (MRI). Laporan Kasus: Kami melaporkan 3 kasus paska rekonstruksi single bundle ACL. Pasien datang dengan diagnosis robekan ACL. Setelah menjalani rekonstruksi ACL, ketiga kasus menjalani evaluasi radiologi pasca operasi. Pasien pertama dievaluasi menggunakan radiografi konvensional, dilakukan pengukuran sudut femoral dan tibialis serta posisi tunnel femoral dan tibialis. Pasien kedua menjalani CT-scan untuk evaluasi posisi tunnel femoral dan tibialis serta lebar dari tunnel. Pasien ketiga dievaluasi pasca rekonstruksi ACL menggunakan MRI setelah 6 bulan pasca operasi. Kami mengevaluasi proses penyembuhan umum, integritas cangkok, posisi tunnel dan pembesaran tunnel. Diskusi : Tujuan rekonstruksi ACL adalah untuk membentuk cangkok isometrik, anatomis dan bebas dari impingement untuk ligamen yang robek. Pada pasien yang mempunyai keluhan yang menyebabkan kegagalan teknis, 80% disebabkan oleh malposisi adalah tunnel femoralis, yang memengaruhi isometri cangkok, konsitensi panjangnya dan tegangan cangkokan selama rentang gerak lutut. Posisi tunnel tibialis penting dalam mencegah impingement cangkok ACL. Simpulan : Ahli radiologi perlu memahami posisi yang tepat dari tunnel femoralis dan tibialis untuk menghindari kegagalan rekonstruksi ACL. Radiografi konvensional dapat menjadi alat awal yang praktis dalam evaluasi pascaoperasi.

The Clock-Face Reference: Simple but Nonanatomic

Correct placement of the femoral and tibial bone tunnels is decisive for a successful anterior cruciate ligament (ACL) reconstruction. Our method of tunnel placement was evaluated as part of quality control at a teaching hospital. The emphasis was placed mainly on investigating the influence of surgical experience on tunnel placement, and the effect of tunnel position on the clinical outcome. Seventeen surgeons with different levels of experience (between 0 and >150 ACL reconstructions) performed endoscopic ACL repair in uniform technique from August 2000 to August 2003 on 50 patients (18 women, 32 men, age range 18-43 years). The patients were available to clinical and radiological follow-up after an average of 19 months. The clinical outcome was classified according to the International Knee Documentation Committee (IKDC) standard evaluation form. The femoral tunnel was evaluated according to the quadrant method of Bernard and Hertel; the position of the tibial bone tunnel was assessed according to the criteria of Stäubli and Rauschnig. The IKDC score revealed 47 (94%) patients with a normal (A) or nearly normal (B) knee joint at follow-up. According to the quadrant method, the femoral canal was situated on average at 29% in the saggital plane. The tibial tunnel was situated on average at 43% of the a.p. diameter of the tibial condyle. Statistical analysis of our data showed no significant correlation between tunnel placement and surgical expertise. However, a highly significant correlation was found (alpha<0.01) between the femoral position of the tunnel in the sagittal plane and the IKDC score. The more anterior the femoral canal, the poorer the IKDC score. The method of tunnel placement in ACL reconstruction being investigated here only showed slight dependence on surgical experience, whereby good short-term clinical outcomes were achieved. Therefore, the method is suitable for application at a teaching hospital. A far too anterior femoral tunnel placement will probably lead to a decline in the clinical result.

Anatomic femoral tunnel and satisfactory clinical outcomes achieved with the modified transtibial technique in anterior cruciate ligament reconstruction: A systematic review and meta-analysis

Femoral tunnel placement is essential for good outcome in anterior cruciate ligament (ACL) reconstruction. In the past, several attempts have been made to optimize femoral tunnel placement. It was observed that the posterior horn of the lateral meniscus was always located directly below to the desired femoral ACL tunnel position, when the knee was brought to deep flexion (> 120°). The goal of the present study was to verify the hypothesis that the posterior horn of the lateral meniscus can be used as a landmark for femoral tunnel placement. Out of a consecutive series of ACL reconstructions done by a single surgeon, 55 lateral radiographs were evaluated according to the quadrant method by Bernard and Hertel. Additionally, on anterior-posterior radiographs the femoral tunnel angle was determined. In the present case series the posterior horn of the lateral meniscus could be identified and used as a landmark for femoral tunnel placement in all cases. The mean tunnel depth was 24 ± 5.1% and the mean tunnel height was 31.3 ± 5.7%. The mean femoral tunnel angle was 41 ± 4.9° using the anatomical axis as a reference. Compared to previous cadaver studies the data of the present study were within their anatomical range of the native ACL insertion site. The suggested technique using the posterior horn of the lateral meniscus as a landmark for femoral tunnel placement showed reproducible results and matches the native ACL insertion site compared to previous cadaveric studies. In particular, non-experienced ACL surgeons will benefit from this apparent landmark and the corresponding easy-to-use ACL reconstruction method. IV.

Objective: Anterior cruciate ligament (ACL) injuries are common among athletes and active individuals participating in sports. ACL reconstruction using the single-bundle technique can be performed through transtibial or anteromedial portals. The transtibial technique carries the theoretical risk of vertical placement of the femoral tunnel in the intercondylar notch. The aim of this study is to assess the efficacy of a free-hand drilled-transtibial technique in achieving optimal graft positioning. Materials and Methods: We analyzed a retrospective series of post-operative knee radiographs in 52 consecutive patients who underwent a single-bundle ACL reconstruction by a single surgeon using this transtibial method, from June 2009 to January 2010. Tunnel positioning was radiographically assessed by an independent single observer, who was not involved in the management of patients. The graft inclination angle, the coronal and the sagittal femoral and tibial tunnel placements were evaluated. Results: Post-operative radiographs of 40 patients (40 knees) were retrospectively evaluated for femoral and tibial tunnel positioning. In the coronal plane, the mean graft inclination angle was 21°, the femoral tunnel was positioned at a mean of 43% lateral to the lateral femoral condyle and the tibial tunnel at a mean of 46% lateral to the medial border of the medial tibial plateau. In the sagittal plane, the femoral tunnel was placed at 84% posteriorly across Blumensaat's line and the tibial tunnel at a mean of 43% along the length of the tibial plateau. The results were consistent with optimal tunnel positioning according to anatomic and clinical studies. Conclusion: The transtibial technique described in this series can achieve optimal tunnel positioning for single-bundle ACL reconstruction.