Switching portal technique in anterior cruciate ligament reconstruction: use of an extra low and medial portal

INTRODUCTION

With the increasing rate of arthroscopic ACL reconstruction being performed everywhere, the incidence of failure and decreased longevity of the reconstructed graft is being encountered very frequently. Although there can be variety of reasons behind this failure- biological failure, new trauma, faulty surgical technique, the most important reason is due to malposition of tunnel placement more frequently that of femoral tunnel.^1-2 According to a data from Multicentre ACL revision society (MARS) 80% of all ACL failure is because of faulty femoral tunnel.³ Anatomic ACL reconstruction is now the method of choice as compared to transtibial technique, the later involves tibial tunnel dependant femoral tunnel placement.^4-6 Every fraction of milimeters is important as far as accurate positioning tunnel placement is concerned for both entry point as well as the correct trajectory. And to get this we need to see whole plot accurately neat and clear as even minor variation in these principles can lead to bad to worse outcomes.

By the use of quadrant method the ACL femoral foot print is located 28-32% of the long axis of the quadrant and 35% of the short axis. There should not be any part of tunnel anterior to the resident’s ridge.^7,8

The center of the tibial foot print should be at the level of posterior edge of anterior horn of lateral meniscus antero-posteriorly and in between interspinous area (40-60 ratio) mediolaterally.^9,10 Surgeons are using standard two portal technique for single bundle ACL reconstruction since time. The purpose of the study is to emphasize the role of an extra low and too medial portal to reconstruct ACL reliably with accurate femur and tibial tunnel positioning.

METHODS

This open ended prospective study was conducted over a period of two and a half years during July 2016 to December 2018 in Department of Orthopaedics, King Georges Medical University, Lucknow.

Inclusion criteria

Inclusion criteria were individuals with age 14-55 yrs; anterior instability of knee after trauma >3 weeks duration.

Exclusion criteria

Exclusion criteria were age <14 and >55 yrs; duration <3 weeks or with swelling; any other co morbidities; patient unwilling to give consent.

All surgeries were performed by single surgeon. Written informed consent from the patients and Ethical approval from research cell King George’s medical university has been taken.

Surgical technique

Patient was positioned supine with Bolster over OT Table so that 60 degree flexion at hip and 90 degree at knee can be achieved whenever required. After giving anaesthesia (GA/RA) a tourniquet was tightened over thigh and surface marking of the knee was done with knee in 90 degree flexed position. High anterolateral visual portal was created just at the level lower pole of patella lateral to patellar tendon by vertical stab incision and dilating with straight artery. Entry was made with blunt trochar and cannula to minimize the damage to the articular cartillage Diagnostic round of the whole knee was performed and confirmation of ACL tear was made. The high anteromedial working portal was made(which would be switched to visual portal when doing femoral tunnel) (Figure 1). A 3^rd new low and more medial (approximately 2 cm to patellar tendon) working portal is made under arthroscopic vision with spinal needle which would reach the proper femoral foot print seen through high medial portal. Femoral tunnel is first drilled with guide wire in free hand technique and then drilled to required diameter according to the diameter of the graft size (keep knee in maximum flexion to prevent tunnel going too posterior)(care should be taken to ensure at least 2.5 mm bony ridge between the tunnel wall and the proximal and posterior wall) it is important to drill approximately 10 mm farther to the desired graft length in the femoral tunnel to allow easy flipping of the endobutton and at least 8 mm of the lateral cortex to be intact to prevent tunnel blowout (Figure 3 and 4) (Table 3). Tunnel is secured with fiber wire with Beathpin.

Switching back to anterolateral portal tibial tunnel is drilled with usual recommended technique in outside in fashion (Figure 5) the graft is then passed and endobutton is flipped towards the femoral side and is secured and tightened with a bioscrew towards the tibial side.

Statistical analysis

Data are reported as mean ± SD or proportions and 95% confidence intervals.

RESULTS

Total 112 ACL reconstructions in 112 patients with at least 3 weeks post injury instability were performed. Out of 112 patients 90 patients were males while rest 22 were females. In total 60 right knee while 52 left knee were operated. On an average mean reporting days to us was found to be 168 days and out of them 103 were only ACL injury while 09 patients were operated for multi ligamentous injury (Table 1A). Mean time in performing surgery was observed to be 43 minutes using this three portal technique. Average femoral tunnel length was found to be 38 mm. Only two cases were complicated by femoral tunnel blow-out which were managed by mini open technique using suture disc (Table 1 B, C).

DISCUSSION

Anatomic and accurate positioning of tunnel placement is key to success in ACL reconstruction. Although ACL anatomy has been well described by radiographs and cadaveric measurements but arthroscopic landmarks are of importance in reconstruction. Whole plot should be visible neat and clear to pin Arjuna’s fish eye (A reference of accuracy in Indian mythology) and to attain this the use of high anteromedial portal for visualization and extra low medial portal to be used as working portal has been proved to be a very good technique for tunnel placement without necessitating the inadvertent use of notchplasty (Figure 2-3). In cases where remnants of ACL hinder the view of footprints, this technique is proven to be superior than two portal technique. In cases where augmentation of ACL is done while preserving the remnant ACL, the use of this extra portal has no match. Snow et al. has mentioned many advantages of anatomical tunnel placement over the ancient transtibial technique which was further reemphasized by lubovitz.¹¹ Bedi et al. has emphasized the importance of accurate tunnel placement on the basis of footprints and landmarks.¹² Paulo et al described the three portal technique for double bundle ACL reconstruction. All these statements are in accordance with the technique presented in this study.

The principle for anatomical ACL reconstruction are to functionally reestablish the ACL to its native dimensions, collagen orientation and insertion sites.

CONCLUSION

Making of one extra medial portal (3^rd portal) and switching it as working portal and high medial portal as a visual portal for femoral tunnel placement is a very easy, reproducible technique which provides a meticulous view of remnants and bony arthroscopic landmarks facilitating anatomical graft placement as compared to two portal technique which limits the proper visualization of femoral insertion site (Table 2). In knee arthroscopy any numbers of portals can be made according to your comfort until you make the joint a sieve. The author suggests the use of this accessory anteromedial portal technique for ACL reconstruction.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: The study was approved by the institutional ethics committee

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