Anterior Cruciate Ligament Reconstruction: Antero-medial Portal vs Trans-Tibial Femoral Tunnel Drilling

The Anterior and Posterior Cruciate Ligaments (ACL and PCL, respectively) are integral components of the knee joint. Along with other soft tissue structures, the ACL and PCL help to confer stability to the knee joint, preventing anterior and posterior translation respectively, of the tibia on the femur.¹ Because of its stabilising role, the ACL may be exposed to tremendous multi-planar forces during strenuous multidirectional and rotational activities activities such as football which may result in compromise of this important ligament.² ACL rupture may cause instability of the knee joint, especially in persons with a lack of other stabilisers of the joint, such as under-developed surrounding musculature. The resulting injury and instability may cause a ‘distrust’ of the knee and may even preclude athletes from pursuing their sport. Current orthopaedic practice offers the possibility of reconstruction of this ligament thereby stabilizing the knee but such an operation affecting a joint so crucial to mobility requires a sound understanding of the knee’s anatomy in order to attain good functional outcomes, not least because of the potential for degeneration of the joint in the long-term.³

The ACL is a ligament which runs from the medial aspect of the lateral femoral condyle superiorly to a more anterior, medial and inferior position on the tibial eminence. The ligament is actually formed by two separate posterolateral and anteromedial bundles.⁴ These bundles become taut during different movements of the knee joint and therefore provide stability during different movements of the knee, effectively performing different functions. The posterolateral bundle of the ACL is taut during extension of the knee joint and confers mostly rotational stability at this extreme of movement. The anteromedial bundle of the ACL on the other hand is taut mostly during flexion and confers mainly anteroposterior stability, preventing anterior translation of the tibia on the femur.⁵

Some forms of surgery employ this specific anatomical knowledge using a so-called double-bundle technique of ACL grafting but other surgeons prefer to use a single-bundle technique for ACL reconstruction. There have been mixed results, however, with no definite consensus on which yields better results.^6-8 In addition to this anatomical knowledge, the ACL’s attachment to both the tibia and femur are also important if an adequate reconstruction is to be performed. This ligament’s femoral attachment is circular to oval in shape and lies posterior to a landmark known as the lateral intercondylar ridge (Resident’s Ridge), with the posterior edge marked by the condyle’s posterior cortex. The main load-bearing part of the ACL consists of ‘direct’ fibres which enter the condyle at an angle approaching 90 degrees (horizontal). There exist more ‘indirect’ fibres which fan off from the main bulk of the ligament and are thought to bear only a small portion of the load on the ACL.^{4, 9-10}

The ACL’s footprint is important to bear in mind during reconstruction as anatomical reconstruction requires the femoral footprint of the graft to be placed through the ACL’s native footprint. There is a growing body of evidence to support a more anatomical placement of the femoral footprint of the ACL during reconstruction.¹¹ Trans-tibial drilling of the femoral tunnel does not respect the native ACL’s anatomy and so this reconstruction is considered non-anatomical. More modern techniques of ACL reconstruction have in fact shifted to a more anatomical method of reconstruction with one such method using an anteromedial portal to the knee joint in order to drill the femoral tunnel. This approach allows the femoral tunnel to be placed in the footprint of the native ACL, with an insertion angle of the graft that resembles anatomical specimens. Results of such reconstructions appear to be more promising.^12-15

The biomechanics of the knee joint are dependant on its anatomy but allow for a deeper understanding of the mechanisms of injury and subsequent pathophysiology. Being a synovial joint with a significant soft tissue component (including both menisci), the knee exhibits two main movements, these being rolling and gliding. Both medial and lateral tibio-femoral points of contact are able to perform both these movements, gliding occurring mostly in flexion with rolling occurring towards extension.¹⁶ In spite of this however, differences between the two compartments occur during extension when rolling preferentially occurs within the lateral compartment. This becomes more obvious at the extremes of extension when a greater gliding movement in the medial compartment allows the tibia to externally rotate on the femur. This movement puts significant strain on the posterolateral bundle of the ACL, the reason for which this ligament may be injured during forced extension of the knee joint such as kicking a football. On the other hand, the anteromedial bundle of the ACL is put to work mainly in flexion where gliding becomes a more prominent movement of the joint, placing more strain on the anteromedial bundle of the ACL.¹⁷

This study aims to examine the results of autologous Bone-Patellar Tendon-Bone (B-PT-B) single bundle ACL reconstruction with drilling of the femoral tunnel through the anteromedial portal and compare these to those obtained from a previous audit in the same centre but using trans-tibial drilling of the femoral tunnel. (Figure 1).

Figure 1

Anteromedial and Trans-tibial approaches to drilling of the femoral tunnel.¹⁸

Materials and Methods

A list of patients who underwent ACL reconstructive surgery as performed by a single orthopaedic surgeon during the period between March 2017 and April 2018 was sorted according to the inclusion and exclusion criteria as listed below and patients were contacted retrospectively by phone. Once contacted, patients were explained the reason for the interview and verbal consent was obtained from every patient. Demographic details and each patient’s status with regards to previous sport and return to sport after the procedure were also recorded. International Knee Documentation Committee (IKDC) forms were completed and a performance score was calculated for each patient. Application of the IKDC form involved the patient responding to a standard set of questions in order to document their current pain and functional status with regards to ACL reconstruction. If any queries arose, consent was gained in order to review the operating notes. The data gained was then tabulated and comparisons made to an audit performed a few years prior (2005-2008). This audit was carried out in the same centre by the same operating surgeon but using a trans-tibial approach to femoral tunnel drilling rather than an anteromedial approach and used the same parameters for evaluation (IKDC score and return to sport). A p-value was then calculated using a Z-test for two proportions, comparing the likelihood of return to sporting activities after each approach.

Inclusion Criteria:

• All patients undergoing single bundle B-PT-B ACL reconstruction via the an anteromedial portal under the care of a single operating surgeon, operated between March 2017 and April 2018

Exclusion Criteria:

• Patients who had not yet had 12 months of post-operative recovery and physiotherapy at the time of data collection
• Patients who had other ligamentous injury noted either intra-operatively or radiographically
• Patients having revision ACL surgery
• Patients having autologous grafts other than B-PT-B
• Patients having a synthetic graft implanted
• Patients having anything other than Meniscectomy performed during the same procedure
• Patients having prior surgery on the same knee other than simple meniscectomy

Results

A total of 83 patients were found to have had ACL reconstruction procedures between the months of March 2017 and April 2018. Of these patients, 40 were excluded. Of the 40 excluded, 1 patient refused to take part in the study and a further 6 could not be traced or contacted. The remaining 33 patients had procedures which included synthetic graft implantation, revision surgery or previous surgeries for more complex meniscal injuries. This left 43 patients who were eligible for this study and these were contacted in turn and asked for consent to partake in the study.

Of the 43 patients, 35 (81.4%) practised football as their primary sport with other sports including rugby, skiing and martial arts among others. All 43 patients did some form of sport prior to injury, most being injured while playing their sport of choice. 65.1% of injuries (28 patients) involved a twisting injury, often when changing direction suddenly while practicing their sport. The majority of patients were male (38 or 88.4%) with only 5 (11.6%) patients being female.

The age of patients included in the study had ages which ranged from 17 to 36 with mean and median ages of 26 and a mode of 29. A total of 25 patients (58%) had a meniscectomy performed at the same operation with 2 patients (4.7%) having had previous arthroscopy. One of these 2 patients had a meniscectomy performed in the first operative procedure.

The results of a previous audit performed in the same centre between 2005 and 2008 are included in table 1 below for comparison, this audit having included a total of 83 patients.

Discussion

The ACL is an important ligament for normal knee biomechanics. Unfortunately however, it is often subject to trauma, especially during sporting activities requiring sudden changes in movement such as football and volleyball.  For this reason, it is important to consider the restoration of normal biomechanics when reconstructing this ligament. In order to do this however a sound anatomical knowledge is required in order to respect the native ACLs anatomy and consequently the normal biomechanics of the knee as best as possible. Indeed, current literature agrees that an anatomical reconstruction of the ACL affords better biomechanics to the operated knee over a less anatomical reconstruction.¹⁹

Considering the importance of anatomy in ACL reconstruction, an anteromedial approach to drilling of the femoral tunnel has been studied in an attempt to improve the ACL graft’s anatomy. Doing this may hence improve the biomechanics of the operated knee with benefits for the patient, including a better functional status, especially when considering high demand activities such as football and other sports. Current evidence is in agreement that an anteromedial approach to drilling of the femoral tunnel provides a better anatomical result when compared to a trans-tibial approach. This is because it allows for positioning of the ACL graft within the native ACL footprint and also a more horizontal placement of the graft within the femoral condyle, similar to native ACL anatomy.^13,20-23

In this study, the authors compare the results of an anteromedial portal approach versus a trans-tibial approach to drilling of the femoral tunnel in ACL reconstruction. In order to do this, a well-documented and validated score was implemented, the IKDC score. This incorporates a number of questions targeted at different aspects of the operated knee’s status including pain, ability to perform activities such as climbing stairs and also more strenuous activities such as sports. In doing this, the authors were able to deduce that patients having had ACL reconstruction with femoral tunnel drilling through an anteromedial portal had better functional results when compared to a trans-tibial approach. This was evidenced by a shift of the IKDC score in the anteromedial approach group toward the upper range with no patients having recorded ‘Below average’ or ‘Poor’ results as compared to 10.9% of patients in the trans-tibial approach group having recorded these results. In addition to this, an anteromedial approach resulted in a higher rate of return to sport with a total of 86% of patients returning to regular sporting activities compared to a more modest 60% of patients in the trans-tibial group, this difference reaching statistical significance. This figure is of particular interest as it signifies the ability of the anteromedial approach to offer a better result to the patient with regards to return to pre-morbid state and function. This in turn may also translate into a better quality of life and improved patient satisfaction.

The results reported here in this study are congruent with the results of other studies published in the literature. Other reports also show an increased rate of return to sport with some also showing improved recovery times. ⁽²⁴⁾ In addition to this, there is also evidence to suggest that revision rate may be lower with an anteromedial approach.²⁵

This study was carried out using the data from the same operating surgeon who was similarly experienced in both techniques. This affords a chance to better compare the techniques themselves as there is no operator difference to consider here. In contrast to this, considering data from a single operating surgeon may mean that results are less relatable to the more general orthopaedic community, especially considering that this particular operating surgeon specialises particularly in this field of orthopaedics. It must also be mentioned that the present study considers relatively low patient numbers. Having said this however, it must be stressed that an anatomical reconstruction of the ACL is of utmost importance and an anteromedial portal approach allows anatomy to be respected better than a trans-tibial approach. If the operator is able to perform either technique therefore, the authors of this study suggest an anteromedial approach to drilling of the femoral tunnel over a trans-tibial approach as there is now a good evidence bank to support this method.

References

1. Hirschmann MT, Müller W. Complex function of the knee joint: the current understanding of the knee. Knee Surg Sports Traumatol Arthrosc. 2015 Oct;23(10):2780-2788
2. Hewett TE, Myer GD, Ford KR, Paterno MV, Quatman CE. Mechanisms, Prediction, and Prevention of ACL Injuries: Cut Risk With Three Sharpened and Validated Tools. J Orthop Res. 2016 Nov;34(11):1843-1855
3. Markatos K, Kaseta MK, Lallos SN, Korres DS, Efstathopoulos N. The anatomy of the ACL and its importance in ACL reconstruction. Eur J Orthop Surg and Traumatol. 2013 Oct;23(7):747-52
4. Irarrázaval S, Albers M, Chao T, Fu FH. Gross, Arthroscopic, and Radiographic Anatomies of the Anterior Cruciate Ligament. Clin Sports Med. 2017 Jan;36(1):9-23
5. Peterson W, Zantop T. Anatomy of the Anterior Cruciate Ligament with Regard to Its Two Bundles. Clin Orthop Rel Res. 2007 Jan;454:35-47
6. Jarvela S, Kiekara T, Suomalainen P, Jarvela T. Double-Bundle Versus Single-Bundle Anterior Cruciate Ligament Reconstruction. Am J Sports Med. 2017 Sep;45(11):2578-2585
7. Torkaman A, Yazdi H, Hosseini MG. The Results of Single Bundle Versus Double Bundle ACL Reconstruction Surgery, a Retrospective Study and Review of Literature. Med Arch.2016 Oct;70(5):351–35
8. Arciero RA, Double-Bundle and Single-Bundle ACL Reconstruction Techniques Did Not Differ in Terms of Clinical Outcomes at 2 or 5 Years. J Bone Joint Surg Am. 2016 Nov;98(22):1933-1934
9. Smigielski R, Zdanowicz U, Drwiega M, Ciszek B, Williams A. The anatomy of the anterior cruciate ligament and its relevance to the technique of reconstruction. Bone Joint J. 2016 Aug;98-B(8):1020-6
10. Siebold R, Ellert T, Metz S, Metz J. Femoral Insertions of the Anteromedial and Posterolateral Bundles of the Anterior Cruciate Ligament: Morphometry and Arthroscopic Orientation Models for Double-Bundle Bone Tunnel Placement—A Cadaver Study. Arthroscopy. 2008 May;24(5):585-92
11. Sadoghi P, Kröpfl A, Jansson V, Müller PE, Pietschmann MF, Fischmeister MF. Impact of Tibial and Femoral Tunnel Position on Clinical Results After Anterior Cruciate Ligament Reconstruction. Arthroscopy. 2011 Mar;27(3):355-64
12. Steiner ME, Battaglia TC, Heming JF, Rand JD, Festa A, Baria M. Independent Drilling Outperforms Conventional Transtibial Drilling in Anterior Cruciate Ligament Reconstruction. Am J Sports Med. Sep 2009;37(10):1912-1919
13. Bedi A, Musahl V, Steuber V, Kendoff D, Choi D, Allen AA, Pearle AD, Altchek DW. Transtibial Versus Anteromedial Portal Reaming in Anterior Cruciate Ligament Reconstruction: An Anatomic and Biomechanical Evaluation of Surgical Technique. Arthroscopy. 2011 Mar;27(3):380-90
14. Liu A, Sun M, Ma C, Chen Y, Sue X, Guo P, Shi Z, Yan S. Clinical outcomes of transtibial versus anteromedial drilling techniques to prepare the femoral tunnel during anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 2017 Sep;25(9):2751-2759
15. Chen H, Tie K, Qi Y, Li B, Chen B, Chen L. Anteromedial versus transtibial technique in single-bundle autologous hamstring ACL reconstruction: a meta-analysis of prospective randomized controlled trials. J Orthop Surg Res. 2017 Nov 7;12(1):167
16. Smith PN, Refshauge KM, Scarvell JM. Development of the Concepts of Knee Kinematics. Arch Phys Med Rehabil. 2003 Dec;84(12):1895-902
17. Dargel J, Gotter M, Mader K, Pennig D, Kobe J, Schmidt-Wiethoff R. Biomechanics of the anterior cruciate ligament and implications for surgical reconstruction. Strategies Trauma Limb Reconstr. 2007 Apr;2(1):1–12
18. Wang H, Fleischli JE, Zheng N. Transtibial Versus Anteromedial Portal Technique in Single-Bundle Anterior Cruciate Ligament Reconstruction. The American Journal of Sports Medicine. 2013 Aug;41(8):1847-56. Figure 1. Femoral tunnel drilling with different surgical tech- niques. The radiographs show the tunnel orientation in the coronal plane from typical patients. p.1849
19. Musahl V, Plakseychuk A, VanScyoc A, Sasaki T, Debski RE, McMahon PJ, Fu FH. Varying femoral tunnels between the anatomical footprint and isometric positions: effect on kinematics of the anterior cruciate ligament-reconstructed knee. Am J Sports Med. 2005 May;33(5):712-8
20. Bedi A, Raphael B, Maderazo A, Pavlov H, Williams 3rd RJ. Transtibial versus anteromedial portal of the femoral tunnel in ACL reconstruction: A cadaveric study. Arthroscopy. 2010 Mar;26(3):342-50
21. Azboy I, Demirtas A, Gem M, Kiran S, Alemdar C, Bulut M. A comparison of the anteromedial and transtibial drilling technique in ACL reconstruction after a short-term follow-up. Archives of Orthopaedic and Trauma Surgery. 2014 April;134(7):963–69
22. Venosa M, Delvogliano M, Padua R, Alviti F, Delcogliano A. Femoral Tunnel Positioning in Anterior Cruciate Ligament Reconstruction: Anteromedial Portal versus Transtibial Technique—A Randomized Clinical Trial. Joints. 2017 Jun 5;5(1):34-38
23. Brown CH, Spalding T, Robb C. Medial portal technique for single-bundle anatomical Anterior Cruciate Ligament (ACL) reconstruction. Int Orthop. 2013 Feb;37(2):253–69
24. A-G E, Samitier G, Alvarez P, Steinbacher G, Cugat R. Anteromedial portal versus transtibial drilling techniques in ACL reconstruction: a blinded cross-sectional study at two- to five-year follow-up. Int Orthop. 2010 Jun;34(5):747-54
25. de Paul Leite Cury R, Simabukuro AM, de Marques Oliveira V, Escudeiro D, Jorge PB, Severino FR, Guglielmetti LGB. Anteromedial positioning of the femoral tunnel in anterior cruciate ligament reconstruction is the best option to avoid revision: a single surgeon registry. 2020 Mar;7:11

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