The Sliding, Interlocking “8-2-Alpha Knot” for Arthroscopic Surgery Wiroon Laupattarakasem, M.D., Pat Laupattarakasem, M.D.  Arthroscopy Techniques  Volume 5, Issue 4, Pages e857-e863 (August 2016) DOI: 10.1016/j.eats.2016.04.003 Copyright © 2016 Arthroscopy Association of North America Terms and Conditions

Fig 1 Method 1 for 8-2-alpha knot tying. (A) Make an overhand loop in the loop limb at the position to place the knot. (B) Turn the right lower part of the loop up diagonally to form the figure-of-8 loops with the main strand and the loop tail joining at the crossing part of the loops. (C) Fold the right loop back around the joining part toward the left loop to form a stack of 2 loops. (D) Insert the post limb from the front into the loops. (E-G) Readjust the loops and lightly pull both limbs to form a slipknot that appears like figure-of-8 loops wrapping around the post. (H-K) Insert the post limb from the back into the loops; this will form a reverse knot pattern. Arthroscopy Techniques 2016 5, e857-e863DOI: (10.1016/j.eats.2016.04.003) Copyright © 2016 Arthroscopy Association of North America Terms and Conditions

Fig 2 Method 2 for 8-2-alpha knot tying. (A) Grasp and hold the loop limb in the right hand with the index finger and the thumb extended. (B) Swing the index finger clockwise to hook the loop strand half around the finger. (C) Use the back of the thumb to retract the main strand. (D) Turn the loop tail upward, crossing the back of the thumb and then over the main strand, and pass between the 2 digits. (E) Grasp the loop tail that is now passing over the crossing part of the 2 loops connecting between the thumb and the index finger. (F) Take the loops off the 2 digits to form the loop stack as in Figure 1C. Arthroscopy Techniques 2016 5, e857-e863DOI: (10.1016/j.eats.2016.04.003) Copyright © 2016 Arthroscopy Association of North America Terms and Conditions

Fig 3 Method 3 for 8-2-alpha knot tying. (A) Hold the loop limb that is crossing over the post limb with the left thumb and index and long fingers. (B) Throw an overhand loop around both limbs. (C) Throw another overhand loop around only the post limb. (D) Wrap the suture over and around the loop limb, and then pass it from underneath into the triangular space formed by the previous loops and the post limb. (E, F) Appearance of the knot before transforming to a figure-of-8 slipknot as shown in Figure 1 F and G by lightly pulling both limbs. Arthroscopy Techniques 2016 5, e857-e863DOI: (10.1016/j.eats.2016.04.003) Copyright © 2016 Arthroscopy Association of North America Terms and Conditions

Fig 4 Mechanism of knot interlocking. (A) An 8-2-alpha slipknot not under loop traction. (B) By applying simultaneous traction of the loop limb on both sides of the knot, the post becomes strangulated or partially flipped. (C) Further traction causes full flipping, and the 2 limbs become intertwined, resulting in an interlocking knot. (D) Close-up view of the interlocking knot that has lost the property of being a post and a loop limb. (E) Detail of the interlocking knot showing an α-α configuration. Arthroscopy Techniques 2016 5, e857-e863DOI: (10.1016/j.eats.2016.04.003) Copyright © 2016 Arthroscopy Association of North America Terms and Conditions

Fig 5 Salvage procedure for premature knot locking. (A) Simulated situation with a prematurely locked knot. (B) The post limb is divided immediately distal to the knot. (C) The knot pusher is used to push the loops out from the proximal post limb to dislodge the short stump. (D) The loops will spontaneously be disassembled after the post has been removed from the knot. Arthroscopy Techniques 2016 5, e857-e863DOI: (10.1016/j.eats.2016.04.003) Copyright © 2016 Arthroscopy Association of North America Terms and Conditions