Page 9 - Arthroscopic Knot Tying: An Instruction Manual

P.2

The last mechanism of knot failure is bone failure. This occurs in tissue apposition constructs that are
implanted in bone such as a suture anchor. Suture anchor pullout can occur if the bone is osteopenic and
unable to resist the forces across the apposed tissue. Suture anchor pullout may also occur if two or more
suture anchors are placed too close together and the remaining local bone is inadequate to resist the
tensile forces across the tissue. It has been recommended that the anchors be placed at least one
centimeter apart to minimize the risk of anchor pullout (4 ). The knot itself represents the weakest point
in the suture-knot configuration (13 ). In an experiment of 720 hand-tied knots, the knot failed by
loosening or breakage in the knot or immediately adjacent to the knot in 710 of the knots (37 ).

Knot Terminology

An arthroscopic knot is constructed by tying one suture limb around another suture limb. One limb is
known as the post limb (also commonly known as the axial limb) and the other limb is known as the loop
limb (also commonly known as the wrapping limb, working end, running end, or free end). Knots are
constructed by tying the loop limb around the post limb (Fig. 1 ). The post is generally chosen as the limb
farthest from the center of the joint.

FIGURE 1. Loop and post configuration.

Arthroscopic Knot Pushers

An arthroscopic knot pusher is a device used to advance the loop down the post limb into the joint to
create the knot. There are many different types of arthroscopic knot pushers (Figs. 2 , 3 ). Included
among these are single-hole knot pushers, double-hole knot pushers (Fig. 4 ) and double diameter knot
pushers like the Arthrex 6th Finger (Arthrex, Naples, FL). Double-diameter knot pushers provide better
loop security compared to standard single-hole knot pushers (5 ).