The 5 strand hamstring reconstruction of the ACL
A fifth strand can be added to the standard 4 strand hamstring. This will increase the size of the graft giving greater strength and increased contact area. In my opinion this is closer to the shape, size, strength and position of the normal ACL.
A 3rd strand of the semi tendinosus tendon is used. Generally about 240 to 250mm of good semi tendinosus tendon is harvested. I usually cut this in to sections of 160mm and about 80mm in length. The 160mm section corresponds to the normal part of the 4 strand graft. The ends of this part of the graft are whip stitched in the usual fashion.
I then whip stitch the ends of the 80mm section going up and down with 6 passes of the suture on both ends. I currently use Magnum wire to suture the 80mm section of the semi tendinosus tendon. At the distal part of the tendon the technique involves tubularisation of the graft. I tension the strands individually to take up the slack.
The size of the graft usually increases by about 2mm in diameter. A 7mm 4 strand graft becomes a 9mm 5 strand graft and an 8mm graft becomes a 10mm graft.
When it comes to fixation of the graft I tie it directly to the loop of the Arthrex retrobutton. I then place the 4 strand part of the graft through the loop as in the normal fashion and then pass it and fix it as I would for a 4 strand graft.
In this technique of 5 strand hamstring graft ACL reconstruction I do not interfere with the normal 4 strand part of the graft. I do not directly suture the 5th strand to it. I believe that even if the 5th strand part of the graft stretches out due to the relatively looser fixation of the tying to the button, it will be splinted by the 4 strands and will not stretch any further. I don’t want to cause any damage to the 4 strand part of the graft. As time goes on it will be integrated in the graft and will become a part of it, going on to give added stability. I also believe that increasing the size of the foot print both on the femoral and tibial sides more closely mimics the normal ACL. I hope that this technique is the next step in ACL reconstruction. I had expected that the double bundle graft would be the best answer but it seems that in understanding the anatomy of the normal ACL, which has come with the double bundle technique, the 5 strand graft is the next step.
Taking a simplified view of drilling of the tibial tunnel, if the angle is at 45 degrees to the tibial surface then a 10mm drill hole will produce an oval shaped exit hole measuring 10mm by 14.14mm on the intra articular side. This will be less with a steeper angle but the principle remains that normal drilling of the tibia and also the femur result in oval shaped exit tunnels. We also know that simply speaking the femoral and tibial attachments of the normal ACL are roughly 17 by 9mm.
With a bigger 5 strand hamstring ACL graft this can more closely get to the size of the normal ACL better than a 4 strand graft.