Double Bundle ACLReconstruction using the Smith & NephewACUFEX™ Director Set forAnatomic ACLReconstructionFrench Anatomic ACL-R Study GroupIn alphabetical order: Guy Bellier MDPascal Christel MD, PhD Philippe Colombet MDPatrick Djian MDJean Pierre Franceschi MDJames R. Robinson MS FRCS (Orth)Abdou Sbihi MD

Knee SeriesTechnique Guide ENDOBUTTON™ CL

Fixation System

*smith&nephew

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IntroductionAnatomical and biomechanical studies have shownthat the anterior cruciate ligament (ACL) consists oftwo main fiber-bundles, anteromedial (AM) andposterolateral (PL), each having different functions(Figure 1). While the AM bundle is more dedicated toanterior tibial translation control, the PL bundle, dueto its orientation, better controls tibial rotation.

Traditional ACL reconstruction is based on thereconstruction of the AM bundle only. However,laboratory studies, gait analysis and intraoperativenavigation measurements have all demonstratedthat single-bundle ACL reconstruction does not fullyrestore the rotational stability of the knee joint. Thismay account for the long term degenerativechanges which have been observed followingtraditional single-bundle ACL reconstruction.

These considerations have drawn our interest to amore physiologic ACL reconstruction based on theanatomy of the native ACL. A study of ACL footprintsallowed measurement of their characteristics andlocation in relation to the bony landmarks of bothfemur and tibia. Smith & Nephew has developedinstrumentation based on these measurements todrill the femoral and tibial tunnels at the properlocations.

The technique described below is based on theperformance of two femoral and two tibial tunnelsfor which the centers correspond to the center ofthe anatomical AM and PL attachment sites. Thefemoral tunnels are created independently from thetibial tunnels. By drilling the femoral tunnels throughthe AM portal, the anatomic location with regard tothe native femoral footprint can be ensured. Whilethe AM bundle is reconstructed with an autogenousdouble or triple stranded semitendinosus graft, thePL bundle is reconstructed with a double- or triple-stranded gracilis graft. According to their availability,other tendon allografts may be used. Graft fixationis achieved with two ENDOBUTTON™ CL on thefemoral side and two CALAXO™ Osteoconductiveinterference screws on the tibial side.

Knowledge of the ACL footprint anatomy andpractical experience with transportal femoral drillingis a prerequisite for this technique.

Anatomic ACL Reconstruction using the Smith & NephewENDOBUTTON™ CL Fixation System

Figure 1

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Patient PreparationPlace the patient supine on the operating roomtable. Apply a pneumatic tourniquet (optional) to theoperative leg after the limb is exsanguinated.Secure a lateral thigh post, which allows movementfrom full extension to full flexion and ensures thatthe foot is supported (Figure 2). Prepare and drapethe leg in normal sterile fashion. Identify and markthe tibial tubercle, the patella, the medial and lateralborders of the patellar tendon, and the medial andlateral joint lines.

Graft Harvesting Make a 3 to 4 cm skin incision over theanteromedial surface of the tibia, at the level of thetibial tubercle midway between the tubercle and theposteromedial border of the tibia. This incision isused for the harvesting and passage of the graftsas well as the creation of the tibial tunnels.

Note: In order to maintain the morphometric ratio ofthe AM and PL bundles, the AM graft is generallymade slightly larger than the PL graft. The AMbundle uses the doubled or tripled semitendinosusgraft, resulting in a 7–9 mm graft diameter. The PLbundle uses the doubled or tripled gracilis graft,resulting in a 5–7 mm graft diameter.

A minimal graft length of 26 cm for the gracilis and28 cm for the semitendinosus tendon arerecommended for double or triple preparation.

Portal EstablishmentEstablish AL (anterolateral) and AM (anteromedial)arthroscopic portals proximal enough to allow adownward view of the tibial footprint. For anatomicACL reconstruction surgery, place these portalsimmediately adjacent to the lateral and medialpatella tendon borders at the level of the inferiorpole of the patella (Figure 3).

Perform a complete diagnostic arthroscopy andaddress any intra-articular pathology (i.e., meniscalor chondral injury) at this time. Leave the tibialfootprint of the ACL intact in order to obtain properlandmarks for guide wire positioning.

Identify the anatomic insertion of the AM and PLbundles of the ACL on the lateral wall of theintercondylar notch. Mark these insertion sites witheither an RF probe or an awl.

Figure 2

Figure 3

AMAL

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It may be useful to switch the scope from the AL tothe AM portal to allow a better view of the lateralwall of the intercondylar notch.

Drilling and Measuring the AM FemoralTunnelDrill the AM femoral tunnel through the AM portalusing either a 4mm or 5mm Smith & NephewOffset Endofemoral Aimer. Bend the knee to 90° toplace the guide, as you normally would in ACLreconstruction cases. Once the guide is in place,slowly flex the knee to between 110° and 120° toensure the proper orientation of the AM tunnel(Figure 4). Advance a 2.4 mm drill tip guide wirethrough the offset endofemoral guide and drillthrough the femur until the guide wire “breaks”through the lateral femoral cortex.

Feel the 2.4 mm guide wire just under the skin afterit exits the cortex to determine its position. Advancea cannulated 4.5 mm ENDOBUTTON™ drill bit overthe passing pin and breach the lateral femoralcortex. Remove the 2.4 mm guide wire.

Use the ENDOBUTTON Depth Probe to measure thetotal length of the AM femoral tunnel and calculatethe appropriate ENDOBUTTON CL length.

AM & PL Graft PreparationAnteromedial Bundle

Fashion the tendon into a double or triple strandedgraft with minimum length of 10 to 14 cm,depending on the size of the knee. Loop the AMbundle through the ENDOBUTTON CL device thatwas chosen based upon the length of the tunnel.Use Smith & Nephew graft sizing tubes todetermine the diameter of the graft.

Posterolateral Bundle

Fashion the tendon into a double or triple strandedgraft, ensuring that its diameter is a minimum of 5mm. Determine the actual diameter of the PLbundle by again using the graft sizing tube. Alwaysloop the PL bundle through a 15 mm ENDOBUTTONCL device (Figure 5 ).

The Smith & Nephew GRAFTMASTER™ II withENDOBUTTON holder provides ease of preparationduring this process.

Figure 4

Figure 5

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Drilling the AM Tunnel SocketAnteromedial Tunnel

Select a Smith & Nephew wingless RCI router orendoscopic drill bit that matches the graft diameterand use it to produce the AM femoral socket. Depthis regulated according to the desired insertionlength and should be 9 to 10 mm greater than thedesired graft insertion to allow for theENDOBUTTON flip (Figure 6).

Drilling the PL Tunnel and SocketPosterolateral Tunnel

Keeping the knee flexed to 120°, insert the Smith &Nephew Anatomic ACLR PL Femoral Aimer with anappropriately-sized post into the AM tunnel. Ensurethat the shoulder of the AM post is in contact withthe lateral wall of the intercondylar notch. Rotate theaimer until the laser mark on the aimer is alignedwith the center of the RF probe/awl mark previouslymade for the PL bundle insertion site. The aimershould be 2 or 3 mm from the cartilage surface(Figure 7).

Proper placement of the aimer is critical to achievingan adequate bone bridge.

Once the aimer is properly placed, insert a 4.5 mmnon-cannulated drill bit and drill through the lateralfemoral cortex (Figure 8). Remove the PL femoralaimer and measure the length of the PL tunnel withthe ENDOBUTTON depth probe. Insert a 2.4 mmdrill tip guide wire through the PL tunnel.

Select a Smith & Nephew wingless RCI router orendoscopic drill bit that matches the graft diameterand use it to produce the PL femoral socket. Depthis regulated according to the desired insertionlength and should be 9 to 10 mm greater than thedesired graft insertion to allow ENDOBUTTONdevice rotation.

Caution: Ensure the router does not breach thelateral femoral cortex, otherwise femoral fixationwith the ENDOBUTTON CL System will becompromised.

Figure 6

Figure 7

Figure 8

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Drilling the Tibial TunnelsAnteromedial Tunnel

Identify the anatomic insertion of the AM and PLbundles of the ACL on the tibia. Mark theseinsertion sites with either an RF probe or an awl.

Use the familiar Smith & Nephew ACUFEX™ DirectorACL Tip Aimer (REF 7205519) set at 55 degrees forthe placement of the anteromedial guide wire. Payattention to the placement of the anteromedialguide wire, which should exit in the center of theAM bundle and not in the center of the ACL. TheAM tibial tunnel in the anatomic reconstructiontechnique is more anteriorly located than intraditional single bundle reconstruction (Figure 9).

Advance a 2.4 mm drill tip guide wire through thetibia (Figure 10). Once acceptable placement of thetibial guide wire is obtained, advance theappropriately-sized cannulated drill bit into the jointspace. Alternatively, undersize the tunnel by 1 mmand use dilators to expand the tunnel to the desireddiameter.

Posterolateral Tunnel

Place the appropriately-sized post on the Smith &Nephew Anatomic ACLR PL Tibial Aimer. Once thepost is secured, insert it into the AM tibial tunneluntil the distal end is flush with the tibial surface.Ensure that the post is not protruding into the jointnor recessed in the tunnel. The tibial aimer has aslot at the tip of the AM tunnel post. This slotshould be oriented to align with the anticipatedcenter of the PL bundle (Figure 11).

Figure 11

Figure 10

Figure 9

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Once proper alignment is achieved, advance thebullet against the tibia. The tip of the bullet islocated on the anterior edge of the superficial fibersof the medial collateral ligament (Figure 12).

The PL tunnel has a more medial and distal entrypoint on the tibial cortex than a standard ACL tibialtunnel.

Advance a 2.4 mm drill tip guide wire through thetibia. Once acceptable placement of the PL tibialguide wire is obtained, advance the appropriately-sized cannulated drill bit into the joint space.Alternatively, undersize the tunnel by 1 mm and use dilators to expand the tunnel to the desireddiameter. An osseous bridge of approximately 2 to 3 mm should remain between the two tunnelsinside the joint (Figure 13).

Final Graft Passage and Fixation Use a 2.7 mm ENDOBUTTON™ passing pin throughthe AM portal to insert two passing sutures ofdifferent colors through the AM and PL femoraltunnels. Use grasping forceps to retrieve the suturesthrough the corresponding tibial tunnels.

Attach a #5 polyester braided suture to one outsidehole of the ENDOBUTTON device to lead and passthe device. Attach a trailing #2 polyester braidedsuture to the opposite outside hole of theENDOBUTTON device to rotate, or “flip”, theENDOBUTTON device as it exits the femoral cortex(Endobutton flip) (Figure 14).

Pass the graft for the PL bundle until it breaches thefemoral cortex and flip the ENDOBUTTON. Pull backon the graft to ensure proper fixation of theENDOBUTTON.

Next, follow the same procedure to pass the graftfor the AM bundle. Flip the ENDOBUTTON deviceand test the fixation.

While holding the grafts, cycle the knee through afull range of motion from 0° to 120° approximately20–30 times (Figure 15).

Mark the grafts that lie external to the tibia with askin pen, close to the tunnel entrances. Visualizethe variation of each bundle from full extension tofull flexion. Generally speaking, the length variation

Figure 13

Figure 14

Figure 12

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on the AM bundle should range between 0 mm and1 mm while the PL bundle length variation rangesbetween 4 mm and 6 mm. Push backward on thetibia, apply tension and fix the AM bundle between45° and 60° of flexion (Figure 16). For fixation, use aSmith & Nephew CALAXO™ OsteoconductiveInterference Screw 1 mm larger than the tunneldiameter and the longest screw possible (Figure 17).

Apply tension and fix the PL bundle. The larger thelength variation of the graft in full range of motion,the closer to full extension that fixation should beperformed. Generally fixation should occur between30° and 10°.

Additionally, if desired, a fixation post can be usedto back up the screw fixation.

Ensure that full range of motion is achieved afterfixation of the AM and PL bundles. It is important to ensure that there is no impingement with theintercondylar notch – especially with the lateralcondyle wall – in full extension, nor with the PCL infull flexion. If necessary, peform a notchplasty.

Postoperative CareThe postoperative regime is identical to single-bundle ACL reconstruction using soft tissue grafts.

Postoperatively, immobilize the knee in fullextension either in a removable posterior sling or in a hinged knee brace that can be locked in fullextension.

Partial weight bearing with crutches, 50 percent ofthe body weight, is allowed for one month.Mobilization is started immediately, giving priority tothe recovery of full extension. CPM may help forflexion. The sling or the brace will be removed whenquadriceps control is re-established, after about 4weeks. Follow standard ACL reconstructionrehabilitation protocol.

Non-cutting, non-pivoting sports are allowed after 3months. Cutting and pivoting activities may beprogressively resumed by 6 months.

Figure 17

Figure 15

Figure 16

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Tricks and TipsTriple Stranded Graft Preparation

It is always possible to utilize a triple stranded PLgraft, due to its short intra-articular length. Thelength of the PL graft can be as short as 70 mm.

Whipstich each end of the graft as normal with anon-absorbable suture. Fold the graft overENDOBUTTON™ CL leaving one side twice as long asthe other. Take the longer side of the graft and wrapit through the ENDOBUTTON CL again, leavingapproximately 2 cm of graft hanging below theENDOBUTTON to allow for grasping and tensioning(Figure 18). Once the graft is tensioned, whipstitchthe three strands of tendon together, just below theloop of the ENDOBUTTON CL. Ensure that the 2 cmtensioning strand is securely sutured to the graft.

Portals

It is important to have proximal portals to ensuredirect visualization of the tibial insertion points ofthe AM and PL bundles from above.

The medial portal should be incised immediatelyagainst the medial edge of the patella tendon. If themedial portal is too far medial there is risk ofdamage to the medial femoral condyle when drillingthe femoral tunnels through this portal.

Femoral Tunnels

The posterior femoral cortex will be open for a fewmillimeters but this does not matter due to thelength of the AM tunnel (i.e. approximately 50 mm)and fixation with ENDOBUTTON.

The Smith & Nephew Anatomic ACLR PL FemoralAimer is designed to maintain an adequate bonebridge between the tunnels. The bone bridge willmeasure approximately 2 mm thick at the entranceof the tunnels in the joint. Proper placement of theaimer is critical to achieving an adequate bonebridge.

Ensure that the shoulder of the AM post is incontact with the lateral wall of the intercondylarnotch. The divergence between the AM and PLtunnels is 15 degrees. In most cases, the length ofthe AM tunnel ranges between 40 mm and 50 mmand the length of the PL tunnel ranges between 30mm and 35 mm.

Figure 18

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The size of the ENDOBUTTON CL should be chosento ensure that at least 15 mm of graft remains withinthe femoral tunnels.

Tibial Tunnels

Preserving the fibers of the AM and PL bundles onthe tibia (Figure 19) will assist in proper placement ofthe tibial tunnels and may contribute to improvedgraft vascularization.

Fixation

In the case of breaking through the femoral cortexwith your router, use a Smith & NephewXTENDOBUTTON™ in conjunction with theENDOBUTTON™ CL to cover tunnels between 6mmand 10mm.

Figure 19

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Additional InstructionPrior to performing this technique,consult the Instructions for Useprovided with individual components— including indications,contraindications, warnings,cautions, and instructions.

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