Knotless Anchors
Lennard Funk, 2008
Challenges of Arthroscopic surgery
Arthroscopic reconstructive surgery poses many challanges for the surgeon. One of these is the tying of arthroscopic knots. To achieve reliable, reproducible knots every time requires a lot of practice and skill. Some surgeons prefer knotless devices for many reasons.
Knots vs. Knotless
Knots are extremely strong and reliable. Well tied knots are strong enough to withstand tendon and bone forces. Arthroscopic knots are the same as those used by climbers and sailors, so knot security is not a concern in the experts hands. Knots are versatile and can be used in any suture repair situation, such as margin convergence for cuff repair or with suture anchors.
Possible disadvantages of knots are a theroretical risk of tissue irritation, potential postoperative joint clicking from large knots and surgeons knot-tying skill. For consistent knot-tying a surgeon must be well practiced in tying knots on models before doing so on patients.
Knotless anchors have the advantage of avoiding the problems above and potentially reducing surgical time as well.
Literature
Currently there is only one published randomised controlled trial comparing knot and knotless repairs - Cho et al. Arthroscopy, 2007. They used the Mitek Bioknotless anchor. They concluded that knotless was less satisfactory, with higher failure rates. However, as Thal pointed out, there were a number of flaws in the study: 66% of knotless group were not included in follow-up, inclusion criteria were established retrospectively and not well matched and many unsupported conclusions were made.
Knotless Suture Anchors (up to 2008)
- Bioknotless anchor (Mitek, J&J).
- Pushlock (Arthrex)
- KINSA (Smith & Nephew)
The author prefers the KINSA anchor, which is unique in that it actually is not truely knotless. It incorporates a sliding, locking knot within the anchor itself. Thus the surgeon does not need to tie the knot themselves. The tension of repair can be adjusted prior to final locking and there are no limitations in tissue capture. It seems to fulfill all the advantages of both the knotless and standard suture anchors.
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