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Year : 2015  |  Volume : 15  |  Issue : 2  |  Page : 181-186

Radiographic (magnetic resonance) evaluation of the anteromedial versus the transtibial technique in anterior cruciate ligament reconstruction

Department of Surgery, Division of Orthopedic, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia

Date of Web Publication6-May-2015

Correspondence Address:
Mohammed Al Sobeai
King Saud bin Abdulaziz University for Health Sciences, Riyadh
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1319-6308.156368

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Purpose: Making the femoral tunnel through the anteromedial (AM) portal is believed to allow an unconstrained position compared with the traditional transtibial (TT) tunnel. Our aim was to compare the AM and TT portals during anterior cruciate ligament (ACL) reconstruction using magnetic resonance imaging (MRI) to identify the three-dimensional (3D) position of the ACL and compare it to the normal ACL. Materials and Methods: The literature was reviewed to identify the angles used for comparison. A case-control study was conducted with AM, TT and control groups. MRI was used to measure the sagittal ACL angle (angle A), the Blumensaat angle (angle B), and the coronal ACL angle (angle C) in the three groups. Results: The sum of squares and mean squares of the angles were used. A comparison of the AM and control groups (A vs. C) showed a P value of 0.417, whereas the P value for the control and TT groups (C vs. T) was 0.001. The P values for the two comparisons with angle C were significant (P = 0.0007 and < 0.0001). The P values for the third angle (angle B) were not significant (P = 0.047 and 0.086, respectively). Conclusion: The 3D position of the ACL for the AM group was closer to that of the control group compared to that of the TT group. Thus, the AM technique was superior to the TT technique in terms of restoring normal anatomy. So, reconstruction of ACL using the AM technique is expected to give better functional result than the TT technique.

  Abstract in Arabic 

نينرلاب يعاعشلإا ريوصتلا قيرط نع يماملأا يبيلصلا طابرلا رامعإ ةداعإ مييقت :ضرغلا.ةيماملأا ةحتفلا ربع ةثيدحلا ةقيرطلا عم ىندلاا قاسلا ربع ةيديلقتلا ةقيرطلا ةنراقمب كلذ و يسيطانغملا
ةقيرطلاو AM ةيماملأا ةحتفلا للاخ يذخفلا قفنلا دييشت نيب ةنراقملا ةساردلا فده :ةساردلا فده مادختساب يماملأا يبيلصلا طابرلا رامعإ ةداعإ يف قاسلا ةمدقم للاخ قفنلا لعج يف TT ةيديلقتلا عم ةنراقملاب كلذو يماملأا يبيلصلا طابرلل داعبلأا ةيثلاث ةيعضولا ديدحتل MRI يسيطانغملا نينرلا.يعيبطلا يماملاا يبيلصلا طايرلا
ةثلاث ةعومجمو نيتقيرطلا عم ةلاحلا ةسارد جهنم قيرط نع ثحبلا يرجأ :اهتانيعو ةساردلا قرط A, ثلاثلاداعبلأا يف يماملاا يبيلصلا طابرلا ايواز سايقل يسيطانغملا نينرلا مادختساو ةطباض.ثلاثلا تاعومجملا يف اهتنراقم و B, C
ةعومجملاب ةثيدحلا ةعومجملا ةنراقم .اياوزلل تاعبرملا لدعم تاعبرملا عومجم ةقيرط تمدختسا :جئاتنلا ةعومجملا عم ةطباضلا ةعومجملل ةميقلا تغلب نيح يف ،0,417 تغلب أطخلا ةميق نأ ترهظأ ةطباضلا 0.0007=P( ةريبك C ةيوازلل نيتعومجملا نيب أطخلا ميق تناكو .A ةيوازلا ةنراقم دنع 0.001 ةيناثلا.يلاوتلا ىلع 0,047 و 0.086 ةمهم ريغ ةميق تاذ B ةيوازلل أطخلا ةميق تناك امنيب .>0.0001( و
ىلإ برقأ AM ىلولأا ةقيرطلا يف يماملأا يبيلصلا طابرلل يثلاثلا دعبلا ةيعضو :جاتنتسلإا ىرخلأا ةقيرطلا ىلع اقوفت AM ةقيرط ترهظأو TT ةيناثلا ةقيرطلا يف اهنم ةطباضلا ةعومحملا نم لضفأ ةجيتن AM ةقيرط يطعت نأ عقوتملا نم هيلعو .يعيبطلا حيرشتلا ةداعتسا ثيح نم TT.يماملأا يبيلصلا طابرلا ءانب ةداعإ يف TT ةقيرط

Keywords: Anterior cruciate ligament, anteromedial portal, knee arthroscopy, reconstruction, transtibial portal

How to cite this article:
Al Sobeai M, Al Turki A, Al Eissa S, Al Azzam S, Al Qahtani H, Al Salman M. Radiographic (magnetic resonance) evaluation of the anteromedial versus the transtibial technique in anterior cruciate ligament reconstruction. Saudi J Sports Med 2015;15:181-6

How to cite this URL:
Al Sobeai M, Al Turki A, Al Eissa S, Al Azzam S, Al Qahtani H, Al Salman M. Radiographic (magnetic resonance) evaluation of the anteromedial versus the transtibial technique in anterior cruciate ligament reconstruction. Saudi J Sports Med [serial online] 2015 [cited 2023 Jun 10];15:181-6. Available from: https://www.sjosm.org/text.asp?2015/15/2/181/156368

  Introduction Top

Anterior cruciate ligament (ACL) reconstruction is the sixth most common orthopedic procedure. [1] Due to variations in graft type, fixation methods, and rehabilitation protocols, it is a challenge to compare the large number of studies and draw conclusions about the various procedural techniques [2] Large, multicenter, randomized studies on ACL reconstruction are not available; therefore, properly performed meta-analyses on current prospective data provide the best objective statistical measures of patient outcomes. Unfortunately, such studies are also rare.

Controversies in ACL reconstruction include graft type, allograft versus autograft, sterilization technique, tunnel placement, fixation methods, and harvesting technique. [1]

Tunnel placement has an important effect on the outcome of the ACL reconstruction procedure. Improper placement of the tunnel can cause posterior cruciate ligament (PCL) impingement or high tension on the graft, leading to graft rupture. In the case of the transtibial (TT) technique for inserting the ACL, PCL impingement occurs when the tibial tunnel is placed in a vertical orientation at an angle >70° from the medial joint line of the tibia, and the femoral tunnel is usually a result of drilling through that tibial tunnel. Placement of the ACL graft vertically at the apex of the notch causes the graft to wrap around the PCL, which causes high tension on the graft when the knee is flexed. High graft tension during flexion causes the graft to stretch and prevents the patient from regaining full knee flexion. [1],[3],[4]

Anatomical ACL graft positioning is considered a key factor for proper postoperative knee function and restoration of the physiological kinematics of the femorotibial joint during ACL reconstruction. A failed ACL reconstructive surgery with persistent knee laxity or constrained knee motion is correlated with improper graft placement. The cranio-caudal and anteroposterior positions of the femoral bone tunnel influence the length and tension pattern of the ACL substitute during knee motion. In particular, anatomical femoral bone tunnel placement is crucial for restoring physiological knee kinematics. Although several studies have shown that single-bundle ACL reconstruction effectively stabilizes anterior tibial translation, it may fail to restore normal rotational knee kinematics. However, placing the femoral bone tunnel more towards the medial wall of the lateral condyle at a 10-o'clock position more effectively resists rotatory loads compared with tunnel placement close to the roof of the intercondylar notch. [5]

The TT femoral tunnel is the traditional technique used for this procedure. The anteromedial (AM) femoral tunnel is a new technique in which the tunnel is formed through the AM portal rather than through the tibial tunnel as in the traditional TT technique. This new procedure allows the femoral tunnel to be prepared unconstrained compared with the TT procedure, and is essential for producing the posterolateral (PL) femoral tunnel during double-bundle reconstruction. An AM portal ensures a parallel angle between the interference screw and the femoral tunnel. In addition, the AM technique is helpful in revision cases in which the old vertical femoral tunnel is avoided. [6],[7]

Nishimoto et al. compared the graft-bending angle of the TT and AM portal techniques during double-bundle ACL reconstruction. The AM and PL graft bending angles after the TT technique were significantly greater than those for the far AM portal technique at low flexion angles (AM: 0_−10_, PL: 0_−50_) (P\0.01). This suggests that use of the far AM portal technique might result in lower stress on the graft at the femoral tunnel aperture, and therefore might reduce graft damage. [8]

Although the AM technique has many advantages, many complications can occur during the transition period from the familiar TT to the new technique. Lubowitz listed all of the possible complications of the AM technique, clarified the principles of the technique, and suggested solutions to the learning curve complications. [6]

Ahn et al. defined several lines on three magnetic resonance imaging (MRI) planes to quantify the angle and placement of an ACL grafted using the single-incision ACL reconstruction technique, through a TT portal. They compared the results of a grafted ACL with those of a native ACL. The grafted ACL of the hamstring tendon and bone-tendon-bone (BTB) grafts on postoperative MRI showed a significant vertical angle in the coronal and sagittal planes compared with the native ACL. The hamstring tendon graft was positioned more obliquely in the sagittal plane than the BTB graft, which had a greater angle of the tibial tunnel, in an attempt to prevent graft-tunnel mismatch. The postoperative MRI showed that the more horizontally the angle of the tibial tunnel is placed in a single-incision ACL reconstruction, the closer to the native ACL will be the graft. [9]

After reviewing the literature and from our intraoperative experience, we think that using the AM portal to make the femoral tunnel will give more horizontal tunnel than using the TT technique. More horizontal tunnel restores the anatomy better than the more vertical ones. Our aim is to compare the anatomy of both the AM and TT groups in relation to normal ACL. We think the AM reconstructed ACL has closer anatomy to normal ACL than the TT reconstructed ones.

  Materials and methods Top

The literature was reviewed before starting the study to identify the relationship between restoration of normal anatomy and its effect on patient function after ACL reconstruction. Then, a quasi-experimental study was planned. Three groups were defined. Two of the groups had different exposures, while the third group was the control group. The treatment groups were exposed to two ACL reconstruction surgical techniques (reconstruction using AM or TT portals). The control group included patients with a normal ACL.

Making a femoral tunnel through the AM portal is believed to allow an unconstrained position compared with the traditional TT tunnel. Insufficient data are available regarding the three-dimensional (3D) position between the two techniques. The anteroposterior and AM positions are important for fewer complications and better knee functioning.

Our aim was to identify which of the two techniques produces an anatomy closer to normal on postoperative MRI. We planned to follow the lines defined by the study of Ahn et al. [9] [Figure 1]. We compared the ACL angle and Blumensaat ACL angle in the sagittal view, and the coronal ACL angle in the coronal view. Three groups of subjects were identified. The first group was the control group (Group C), which included MRI performed on patients with an intact ACL. The second group included MRI of patients post-ACL reconstruction using the traditional TT technique (Group T). The third group included patients who underwent the new trans-AM portal technique post-ACL reconstruction (Group A).
Figure 1: The three angles identified by Ahn et al.[1] were used to determine the position of anterior cruciate ligament in space. a: ACL angle, b: Blumensat angle, c: Coronal ACL angle.

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The primary objective was to identify the anatomical position of the ACL or ACL graft. The secondary objectives included age and gender, comorbidities, postoperative level of sports activity (from the chart or patient if possible), timing of surgery after diagnosis, type of graft used, type of surgical procedure, postoperative healing of the graft, and postoperative complications.

Subjects were collected from an operating room database. All patients who underwent ACL reconstructions between January 2008 and November 2012 were reviewed, and the size of the groups was chosen according to the smallest group. The medical records were reviewed to identify the technique used on each subject. The inclusion criterion was patients 18-40 years, and the exclusion criteria were patients lost to follow-up, those with an infection in the same knee, knee deformities diagnosed preoperatively, presence of signs of knee osteoarthritis, and patients who re-tore the graft.

The control group population was collected from the MRI hospital database. All knee MRI performed between July and December 2012 were reviewed and analyzed. Sixty cases were chosen for inclusion. All MRI in the control group was of knees with other pathologies and the ACLs were intact. The control group demographics were similar to those of the other two groups. The same protocol was used for all MRI in all groups.

During the postoperative follow-up period, participants from the AM and TT groups were invited to participate in the study by a research coordinator. Participants who agreed to participate and signed an informed consent form were recruited. The participants were requested to complete a questionnaire based on six questions; they then underwent an MRI scan. All MRI was performed according to the following protocol.

  • Each MRI included the common geometric planes usually used to identify knee pathology
  • Sagittal and coronal view for all patients
  • Sagittal and coronal angle measurements.
After classifying the subjects into the two groups, the MRIs were examined. An independent radiologist, who was blinded to the technique used, measured the three angles and recorded them on a specified table. The angles were defined as follows:

  • Sagittal dimension: The sagittal ACL angle (angle A) was the angle between a line parallel to the distal portion of the ACL, while the other line was tangential to the most anterior aspect of the tibial eminence and perpendicular to the tibial axis
  • Blumensaat ACL angle (angle B): The angle formed by a line parallel to the distal ACL and the Blumensaat line, parallel to the intercondyler roof
  • Coronal dimension: Coronal ACL angle (angle C), the intersection of a line parallel to the ACL distal portion and a line through the tibial articular surface.
Statistical analysis

We characterized the demographics of the subjects using a comprehensive univariate analysis. Categorical variables, such as comorbidities, postoperative complications, and postoperative sports activity levels, are reported as proportions [n, %]. Continuous variables, such as age, knee angles, and time from diagnosis to surgery, are presented as means and standard error. The Chi-square test was used to compare the presence of comorbidities, postoperative sports activity levels, and postoperative complications between the groups.

Prior to conducting the final analysis of the angles, the data were checked for outliers. Two of the angle B measurements were deemed outliers. The overall analysis was completed for the entire dataset and for the dataset after removal of the outliers to quantify the impact of those two outliers on the results. The multivariate analysis was performed both with [Table 1] and [Table 2] and without [Table 3] and [Table 4] the two outliers. The results were similar, although removing the outliers confirmed the hypothesis that angle B did not differ among the study cohorts.
Table 1: Original multivariate analysis results (with outliers) and individual results for angles A, B, and C

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Table 2: Comparison of the study cohorts (with outliers)

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Table 3: Multivariate analysis results (without outliers) and individual results for angles A, B, and C

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Table 4: Comparison of the study cohorts (without outliers)

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  Results Top

Ninety-four subjects were involved in the study. Thirty-four patients were included in the treatment groups (AM and TT, n = 17 each). The control group comprised 60 MRIs of subjects with a normal ACL from between July and December 2012.

The mean age of the overall homogeneous cohort was 28.37 ± 0.61 years. The times from diagnosis until surgery in Groups A and T were almost identical (503.82 ± 92.87 days for Group A and 522.35 ± 67.82 days for Group T). Fifteen of seventeen (88.24) subjects in Group A were healthy and had no comorbidities. However, only 11 of 17 (64.71%) the Group T patients were completely healthy [Table 5].
Table 5: Demographic and clinical characteristics of the study cohorts

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No significant differences were observed regarding co-morbidities, postoperative complications, or postoperative sports activity levels between Group A and Group T patients [Table 5].

The sum of squares and the mean sum of squares for all three angles are shown in [Table 1] and [Table 3]. A significant difference was observed between angles A and C. However, angle B was too small and to show a significant difference among groups. This indicates that the Blumensaat angle did not differ between the groups. In contrast, the differences between angles A and C were significant, and so could be used to compare the groups.

[Table 2] and [Table 4] shows that the P value of angle B indicated borderline significance among the groups. In addition, the P values also indicated nonsignificance for angles A and C between the control group and the treatment groups collectively. The P value indicated borderline significance between the control group and Group T, which explained the significant difference in the anatomy of the 3D space. This observation was not seen comparing control and group A in both angles A and C as P value was not significant.

  Discussion Top

We found a significant difference between the two techniques. It was easier to restore anatomy to one closer to the normal ACL anatomy regarding the position in intraarticular space using the AM portal to make the femoral tunnel. The sagittal and coronal angles were the most important, as they showed differences. Angle B (Blumensaat angle) was small and did not differ among the three groups.

Our results are similar to those reported previously. However, most studies used the femoral tunnel or femoral footprint (with or without the tibial tunnel and footprint) as the primary factor for comparison, while others used the graft itself. Dargel et al., [5] Hantes et al., [10] and Bowers et al. [11] used the tunnel and footprint to compare the AM and TT techniques, and reported similar results. Ours is the first study to evaluate the position of the graft itself in 3D space.

Schairer et al. [12] used MRI to evaluate the translational and rotational kinematics in extension and 30°-40° flexion to compare the AM and TT techniques. They compared the reconstructed knee with the normal knee in the same patient in each group. The results showed similarity between the normal group and the AM group. However, when comparing the operated knee and the control knee, they found greater tibial rotation in flexion and more tibial external rotation in extension in the TT group. The authors concluded that there was more laxity in the TT group. However, they could not explain the increased contact in the lateral compartment in the AM group when compared to the controls.

  Summary Top

Using the AM portal to make a femoral tunnel produced better results regarding anatomy compared to use of the TT portal. Many studies have shown even better results regarding kinematics and function secondary to superior restoration of a normal anatomy.

  Aknowledgment Top

We wouldlike to thank King abdullah International Medical Research Center as they funded all the expenses of our research including MRI expenses.

  References Top

Prodromos CC, Fu FH, Howell SM, Johnson DH, Lawhorn K. Controversies in soft-tissue anterior cruciate ligament reconstruction: Grafts, bundles, tunnels, fixation, and harvest. J Am Acad Orthop Surg 2008;16:376-84.  Back to cited text no. 1
Frank CB, Jackson DW. The science of reconstruction of the anterior cruciate ligament. J Bone Joint Surg Am 1997;79:1556-76.  Back to cited text no. 2
Howell SM, Gittins ME, Gottlieb JE, Traina SM, Zoellner TM. The relationship between the angle of the tibial tunnel in the coronal plane and loss of flexion and anterior laxity after anterior cruciate ligament reconstruction. Am J Sports Med 2001;29:567-74.  Back to cited text no. 3
Simmons R, Howell SM, Hull ML. Effect of the angle of the femoral and tibial tunnels in the coronal plane and incremental excision of the posterior cruciate ligament on tension of an anterior cruciate ligament graft: An in vitro study. J Bone Joint Surg Am 2003;85-A: 1018-29.  Back to cited text no. 4
Dargel J, Schmidt-Wiethoff R, Fischer S, Mader K, Koebke J, Schneider T. Femoral bone tunnel placement using the transtibial tunnel or the anteromedial portal in ACL reconstruction: A radiographic evaluation. Knee Surg Sports Traumatol Arthrosc 2009;17:220-7.  Back to cited text no. 5
Lubowitz JH. Anteromedial portal technique for the anterior cruciate ligament femoral socket: Pitfalls and solutions. Arthroscopy 2009;25:95-101.  Back to cited text no. 6
Lopez-Vidriero E, Hugh Johnson D. Evolving concepts in tunnel placement. Sports Med Arthrosc 2009;17:210-6.  Back to cited text no. 7
Nishimoto K, Kuroda R, Mizuno K, Hoshino Y, Nagamune K, Kubo S, et al. Analysis of the graft bending angle at the femoral tunnel aperture in anatomic double bundle anterior cruciate ligament reconstruction: A comparison of the transtibial and the far anteromedial portal technique. Knee Surg Sports Traumatol Arthrosc 2009;17:270-6.  Back to cited text no. 8
Ahn JH, Lee SH, Yoo JC, Ha HC. Measurement of the graft angles for the anterior cruciate ligament reconstruction with transtibial technique using postoperative magnetic resonance imaging in comparative study. Knee Surg Sports Traumatol Arthrosc 2007;15:1293-300.  Back to cited text no. 9
Hantes ME, Zachos VC, Liantsis A, Venouziou A, Karantanas AH, Malizos KN. Differences in graft orientation using the transtibial and anteromedial portal technique in anterior cruciate ligament reconstruction: A magnetic resonance imaging study. Knee Surg Sports Traumatol Arthrosc 2009;17:880-6.  Back to cited text no. 10
Bowers AL, Bedi A, Lipman JD, Potter HG, Rodeo SA, Pearle AD, et al. Comparison of anterior cruciate ligament tunnel position and graft obliquity with transtibial and anteromedial portal femoral tunnel reaming techniques using high-resolution magnetic resonance imaging. Arthroscopy 2011;27:1511-22.  Back to cited text no. 11
Schairer WW, Haughom BD, Morse LJ, Li X, Ma CB. Magnetic resonance imaging evaluation of knee kinematics after anterior cruciate ligament reconstruction with anteromedial and transtibial femoral tunnel drilling techniques. Arthroscopy 2011;27:1663-70.  Back to cited text no. 12


  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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