nylon lateral button suture packs

Mono-filament nylon remains the most commonly used material for lateral suture techniques. Although less strong and more prone to premature failure than the braids, many surgeons prefer its handling characteristics. Its mono-filament nature makes it more forgiving to aseptic technique and its ability to stretch allows it to also be more forgiving to isometric placement. These can be very distinct advantages. Despite this, maximising isometry should always be the aim as it will help limit the joint becoming excessively tight or excessively loose during flexion/extension, prolonging the cycle life of the prosthesis and its attachments as well as providing better mechanical function through a greater range of motion. Isometry for lateral suture techniques is improved by using tibial anchorage points more caudal and more proximal than originally described. The most isometric anchorage points on the tibia are in the region of the Tubercle of Gerdy or Gerdy’s Sister (the two prominences either side of the long digital extensor grove). Although Gerdy’s sister may provide the more isometric anchorage point of the two, the Tubercle of Gerdy itself may provide a more mechanically advantageous anchorage point in resisting cranial tibial thrust. Using the most frequent method whereby the suture is placed through a tibial bone tunnel and then back in a loop under the patella ligament (see lateral suture technique) becomes progressively problematic as the tibial bone tunnel is placed more caudally. The suture assumes a more unpredictable path under the patella ligament on its return loop, which may then start to impinge on intra-articular structures including the lateral femoral condyle. If there are osteophytes present on the margin of the lateral trochlea ridge, the suture may rub over these during flexion/extension resulting in abrasion, bruising and pain. Lateral button techniques solve this problem as both ends of the line pass through the same bone tunnel emerging from the same hole on the lateral aspect of the tibia in the region of the Tubercle of Gerdy. This change in path makes the prosthesis less liable to rub against the lateral femoral condyle and the whole loop is kept more reliably extra-capsular. For a caudally positioned tibial bone tunnel, many surgeons find lateral button techniques easier to perform well compared with the standard lateral suture technique. As with the more traditional lateral suture techniques, the anchorage position on the femoral aspect of the joint is the lateral fabella/fabello-tibial ligament. Where the lateral fabella/fabello-tibial ligament offers insufficient security, a second bone tunnel (a femoral bone tunnel) or a suture anchor may be used instead, providing a femoral anchorage point just cranial and just distal to the lateral fabella. The LigaFiba® Isotoggle and the Arthrex Tightrope are examples of techniques designed to specifically take advantage of combined tibial and femoral bone tunnels. Because of the increase in suture working length, low stretch braids are recommended for techniques involving two bone tunnels. Suture anchor pins, suture screws, Arthrex Corkscrews, FASTak anchors, devices such as interference screws and the Arthrex SwiveLock are examples of some of the devices available for achieving suitable anchorage in the femoral condyle. For techniques using any of these anchors, the high strength braided materials are again recommended because of their increased abrasion resistance against the anchor. Medical grade ultra-high-molecular-weight-polyethylene (UHMWPE) is the material of choice for the lateral buttons, providing excellent biocompatibility, strength and shock absorption, whilst being soft enough to minimise suture wear. These buttons are recommended for use with nylon techniques. High strength braids such as LigaFiba® and Fiberwire are stronger than the UHMWPE buttons and where very high peak or chronic loading is expected, such as with very heavy or active patients, where good isometry cannot be achieved or in select patients with steeper tibial plateau angles, they may fail and the stronger titanium buttons can be used instead.