CASE REPORT

Out-in aimer for PL bundle in double-bundle ACLreconstruction based on standard single-bundle technique

Antonio Maestro & Luis Rodriguez

Received: 11 December 2011 /Accepted: 13 April 2012 /Published online: 2 May 2012# EFORT 2012

Abstract We describe a new hybrid double-bundle (DB)anterior cruciate ligament (ACL) reconstruction techniqueperformed through a single tibial tunnel, which is based inthe standard single-bundle (SB) reconstruction technique,but adding a posterolateral (PL) femoral bundle. The ar-throscopy was performed adopting a standard two-portaltechnique using an anterolateral portal (ALP) and an ante-romedial portal (AMP). The anteromedial (AM) femoralbundle was created by means of one of the so-called lowfemoral tunnelling techniques from the AMP. After chang-ing the arthroscopy portals, the PL bundle tunnel is drilledoutside-in with the aid of a specific aimer from ALP. Sub-sequently, using a standard tibial technique, the AM femoralbundle is first fixed; secondly, both bundles are fixed to thetibia and, finally, the PL femoral bundle, at different kneepositions. Our method offers a safe and easy way to performa DB ACL reconstruction procedure by using an additionalfemoral PL bundle in the SB standard reconstructiontechnique.

Keywords Anterior cruciate ligament . Double bundle .

Posterolateral tunnel

Introduction

Given the greater knowledge on anterior cruciate ligament(ACL) tear anatomy and the restrictions of conventional tech-niques, a double-bundle (DB) reconstruction concept has beendeveloped, which aims at obtaining a more functional and

resistant graft. Most literature describes the use of a doubletibial tunnel [1, 2], as well as DB techniques with a singletibial tunnel [3, 4].

Intercommunication between tunnels [1] and the techni-cal difficulties to locate the exact sites of femoral insertion[5, 6] represent another limitation when applying the men-tioned DB techniques. The technique that we describeallows for a hybrid DB reconstruction, applying an inside-out arthroscopic approach for the anteromedial (AM) bundleand an outside-in approach for the posterolateral (PL) bun-dle by means of a single-tunnel standard tibial technique.

Surgical technique

In all cases, we use the regular knee arthroscopic surgeryprocedure and the standard anterolateral portal (ALP) and ananteromedial portal (AMP; the latter just above the anteriorhorn of the internal meniscus) to view and confirm the tears.Once the ACL complete tear is assessed, the autologoushamstring tendons (gracilis and semitendinosus) are har-vested. Both tendons are folded in two to double the thick-ness of each bundle and to obtain a diameter of 6–7 mm forPL bundle (gracilis) and of 7–9 mm for AM bundle(semitendinosus).

Once the femoral and tibial insertions are measured—inorder to confirm the anatomical indication for the technique—the AM femoral tunnel is drilled through the AMP with theknee flexed at 95–100° (Table 1). The insertion site is locatedusing a Kirschner wire at 10:30–11:00 clockwise for the rightknee and at 13:30–14:00 clockwise for the left knee; the mostposterior position is selected in order to preserve a 2-mmdistance from the tunnel with respect to the posterior wall ofthe external femoral condyle’s internal face. The tunnel iscompletely drilled and measured using the regular EndoButton

A. Maestro (*) : L. RodriguezFREMAP,Gijon, Spaine-mail: doctorantoniomaestro@meditex.es

Eur Orthop Traumatol (2012) 3:147–149DOI 10.1007/s12570-012-0102-1

CL technique (Smith & Nephew Endoscopy, Andover, MA),and a suture thread is passed through and left into the tunnel.

At this point, we switch arthroscopic portals in order touse AMP as the viewing portal and ALP as the workingportal. The specific femoral aimer (Fig. 1) is then inserted todrill the PL femoral tunnel outside-in from ALP. Once theball at the far end of the aimer (Fig. 2) is placed in the AMtunnel—previously drilled—an 11-mm distance is preservedfrom the central point of both tunnels, so the ball canbe accommodated inside the femoral tunnel and there-fore increase or reduce the inter-tunnel distance. Theaimer is placed externally, in the three space dimen-sions, at approximately 2 cm from the external epicon-dyle of the femur. The PL femoral tunnel is performedoutside-in inserting a Kirschner wire and using a cannu-lated reamer (Fig. 3).

Once the tibial entry point was localized at the centre ofthe footprint or slightly posterior to the insertion of theanterior horn of the external meniscus, a tibial tunnel isperformed adopting the standard technique, with a single-bundle drill guide (Smith & Nephew Endoscopy, Andover,MA) and preserving the intra-articular borders of the tibialfootprint. The angulation of the tibial tunnel should be 50°in the sagittal plane and 30° in the coronal one.

Once the three tunnels have been created, the suturethreads in both femoral tunnels are retrieved trough the tibialtunnel, and the gracilis tendon for the PL bundle is insertedin first place. Afterwards, the semitendinosus tendon is alsoinserted using the standard technique for bundle fixation

with EndoButton CL (Smith & Nephew Endoscopy, And-over, MA) [7]. Tibial fixation is then carried out with theknee flexed at 40° using a Biosure (Smith & NephewEndoscopy, Andover, MA) interference screw 1 mm widerthan the tunnel’s size. Finally, with the knee flexed at 20°,the PL bundle is fixed with another interference Biosure(Smith & Nephew Endoscopy, Andover, MA) screw,inserted outside-in, and also 1 mm upsized than the tunnel’sdiameter.

All patients followed the same postoperative rehabilita-tion protocol, consisting on immediate partial weight bear-ing, protected by a brace in full extension for 3 weeks.Immediate mobility of 0–30° was allowed during the firstweek, and of 0–60° between weeks 2 and 3. Free movementand closed kinetic chain exercises were permitted at 3 weeks,cycling at 6 weeks, and straight, flat surface running at12 weeks [8, 9].

Discussion

Clinical trials [2, 3], anatomic [10] and biomechanical [11],have shown that DB techniques provided better control ofanterior–posterior and rotational stability. However, severalstudies [1, 4] suggested that this functional improvement

Table 1 Steps

1. View and verification of the femoral insertion size through AMP.

2. Creation of the AM femoral tunnel through the AMP using a “low” standard technique.

3. Portals are switched and PL femoral tunnel is drilled outside-in using a specific aimer through ALP.

4. Standard tibial tunnel drilling.

5. Bundle fixation: first, AM as per standard EndoButton; second, both bundles in the tibial tunnel with a screw; and, finally, the PL bundle withanother screw outside-in.

Fig. 1 Specific outside-in drilling aimer

Fig. 2 Intra-articular view. Far end of the aimer with the ball accom-modated in the AM femoral tunnel already drilled and exit of theKirschner wire through the target hole

148 Eur Orthop Traumatol (2012) 3:147–149

could also be achieved adding a second PL bundle to theconventional single-bundle ACL reconstruction.

We believe that when performing an AM femoral tunnelthrough the AMP without damaging the internal [5] femoralcondyle, the drilling must be carried out in a lower positionthan usual, or closer to the internal meniscus, at a highdegree of knee flexion of at least 90°. Having previouslyrevealed the benefits on rotational stability of a lower andmore lateral or oblique femoral tunnel in order to avoid graftverticalization, at zero time [12–14], we consider that byadding a second PL bundle at an even lower and morelateral and oblique position, we would achieve greater sta-bility (in particular, rotational stability) [15].

On the other hand, the option of using two tibial tunnelsis technically more complex as if one of them is not in thecorrect position, the other tunnels might be negatively af-fected. If inter-tunnel communication is also taken intoaccount, as shown in up to 42.8 % of cases [1], we areinclined to think that a single tibial tunnel might be benefi-cial as more bone quantity is preserved and the aforemen-tioned possibilities are prevented.

Acknowledgments We wish to thank to Massimiliano Crespi for theelaboration of the artwork related to this project and Maria de la Fuentefor the translation.

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Fig. 3 Extra-articular view. Femoral tunnel holes already created withthe corresponding outside-in aimer in the PL

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