Arthroscopic Knot Tying

CHAPTER 5 Arthroscopic Knot Tying

The last 2 decades have been a period of dynamic and exciting growth in the field of reconstructive arthroscopy. The drive of patient demand, availability of improved instrumentation and implants, and increasing acceptance of arthroscopic reconstructive techniques by the orthopedic community have all fueled development of increasingly complex arthroscopic reconstructive surgical procedures. The ability to approximate tissue with confidence is a cornerstone of complex arthroscopic procedures and integral to this advancement has been the evolution of arthroscopic knot tying. Unfortunately, development of arthroscopic knot tying skills has proven a stumbling block to many arthroscopists because arthroscopic knot tying is not as intuitive as open knot tying. Recognizing this frustration, many device and implant manufacturers and a number of innovative orthopedic surgeons have devised ways whereby an orthopedist can accomplish some of these reconstructive techniques without the need for tying knots arthroscopically.18 These techniques are, by their nature, dependent on a particular piece of equipment or implant, which subject to the same risk of failure at the time of surgery as any other implant or device. Thus, although these techniques may allow a surgeon to bypass knot tying in some cases, the prudent orthopedist would not undertake a complex arthroscopic reconstructive procedure that relies on tissue fixation without the ability to accomplish basic arthroscopic knot tying as a backup plan. Perhaps more importantly, the ability to tie knots arthroscopically also gives the reconstructive arthroscopist freedom to tailor specific reconstructions to the needs of the patient without being constrained by those options allowed by knotless devices.


Several basic instruments, both disposable and reusable, as well as preferred suture material are routinely needed for arthroscopic knot tying. The surgeon must ensure that these items are readily available before undertaking any procedure that will require arthroscopic knot tying.


The use of cannulas for arthroscopic knot tying helps minimize entanglement of soft tissue in the knot, one of the primary stumbling blocks in arthroscopic knot tying. By passing the knot through the smooth lumen of a cannula instead of directly through muscle fibers and other soft tissue while entering the joint, soft tissue that might become entangled within the knot is effectively bypassed.

Many manufacturers offer disposable cannulas made of clear plastic. These clear cannulas allow the surgeon to see the knot as it is advanced into the joint, which can be a great help in understanding and visualizing the knot seat properly, and any inadvertent twisting or tangling.

Cannulas with threads or blunt spikes on their outer barrel are also commonly available. These features help minimize the tendency of the cannula to slip out of the portal, effectively linking the cannula to the joint wall as instruments are passed in and out during lengthy or complex procedures in which soft tissue swelling can affect portal placement. An additional benefit of this fixation between the cannula and joint wall is that when the cannula is drawn away from the operative field by applying an outward pull, the joint wall is also drawn away from the operative field. This increases space for visualization, which can be a great benefit when visualization is otherwise suboptimal.

Another characteristic that varies among different cannulas is the degree of flexibility of the cannula itself. Flexible cannulas can deform slightly to allow passage of an instrument that would otherwise require a larger diameter cannula. This allows use of smaller cannulas in many cases while still allowing passage of full-sized instruments.


The arthroscopic surgeon has a rich variety of sutures from which to choose. They offer great variation in material qualities such as strength, surface texture, resistance to fraying, and permanence. The ideal suture would provide secure fixation with a minimally bulky knot, have excellent resistance to mechanical abrasion, provide minimal resistance when the knot is being advanced, and provide excellent resistance to knot retreat or loosening. Suture of at least 27 inches in length is needed for effective use of most knot pushers. For a dual-lumen single-hole knot pusher, a minimum suture length of 36 inches is required.

The decision between dissolving (e.g., PDS II, Ethicon, Somerville, NJ) and permanent (e.g., Ethibond Excel, Ethicon) suture depends both on surgeon preference and situation-specific factors such as the nature of the reconstruction and the particular tissue being approximated in the process of that reconstruction. Historically, monofilament suture has been easier to pass with available arthroscopic suturing instruments but in general is more difficult to tie securely,1012 presumably because of differences in surface characteristics of the two types of suture.

A new class of high-strength braided suture incorporating ultra–high-molecular-weight polyethylene (UHMWPE) has recently become available. These sutures, including FiberWire (Arthrex, Naples, Fla), Orthocord (DePuy-Mitek, Raynham, Mass), Hi-Fi (ConMed Linvatec, Largo, Fla), Ultrabraid (Smith & Nephew, Andover, Mass), Force Fiber (Stryker Endoscopy, San Jose, Calif), MagnumWire (ArthroCare, Sunnyvale, Calif) and MaxBraid PE (Biomet, Warsaw, Ind), have been shown to have improved mechanical properties compared with traditional suture materials, but have also been shown to have different knot security qualities.1317 These differences in knot security qualities, presumably caused by differences in surface properties, mandate the need for additional half-hitches to lock these knots. One recent study has demonstrated that a total of four locking half-hitches backing a sliding arthroscopic knot is not enough to prevent knot slippage reliably with these high-strength sutures.17 The authors did not give a recommendation regarding the appropriate number of locking half-hitches needed. Other investigators have suggested that the addition of two locking half-hitches beyond the number that would be used to secure more traditional suture materials is sufficient for reliable knot security.14

Some of the newer high-strength sutures provide greater bulk than the same knots tied with traditional sutures.13 Selecting a knot with a lower profile may be very important when using newer high-strength sutures. The surgeon should also be aware that damage to gloves and even finger skin tears can be sustained when tying vigorously with these high-strength suture materials.18 Moderation of vigor when tying any knot is sensible, especially when tensioning the tissue loop to avoid tissue strangulation.

Knot Pushers

Several different knot pusher designs are available to the arthroscopic surgeon—single-hole, double-hole slotted, mechanical spreading, and dual-lumen single-hole. Single-hole knot pushers are the most commonly used type because they can easily push a knot down by placement on the post limb, or pull a loop down by placement on the wrapping limb. Double-hole knot pushers can be used for these tasks as well, but their added size and bulk confer no advantage and can complicate passage of individual knot loops. Double-hole knot pushers find their main use in correcting twists of the suture limbs prior to knot tying. Both suture limbs are threaded through the knot pusher and the pusher is advanced to the target tissue intra-articularly. Any twist of the sutures is immediately evident and can be corrected with a simple clockwise or counterclockwise turn of the knot pusher as both limbs are captive in the tip of the knot pusher. Slotted knot pushers function similarly to single-hole knot pushers, but allow the knot pusher to be applied and removed from the suture strand without having to withdraw the knot pusher from the joint. This capability can be a liability, however, if the knot pusher is inadvertently separated from the intended suture limb during the process of tying. The incomplete loop of the knot pusher tip also opens the door for soft tissue entanglement. The dual-lumen single-hole knot pusher is designed to hold tension in that portion of the knot already passed while additional throws are tied and advanced. Investigation has shown this knot pusher design to be very effective in achieving loop security during arthroscopic knot tying.19 This knot pusher does however represent a per-use cost (it is disposable), requires use of longer sutures (36 instead of 27 inches), and may require a greater degree of technical proficiency. The dual-lumen single-hole knot pusher is most useful when the surgeon has to tie a nonsliding knot. These nonsliding knots do not have a sliding component to hold temporary tension in the initial (tissue) loop while additional securing throws are being passed. By virtue of its design, the dual-lumen single-hole knot pusher provides this tension, and therefore good loop security, even with simple half-hitch–based nonsliding knots.

In summary, a single-hole knot pusher is a good choice for a primary knot pusher because it has the greatest overall utility for passage and tensioning of knot loops. A double-hole knot pusher has the quickest ability to detect and correct suture twisting prior to tying and is a great adjunct to a single-hole knot pusher. A dual-lumen single-hole knot pusher is used primarily when tying nonsliding knots.


Jun 19, 2016 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on Arthroscopic Knot Tying

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