Syndesmosis fixation can be performed for those injuries indicated to undergo operative intervention. There are multiple methods of syndesmotic fixation to include both screw fixation as well as fixation with a suture button or tension wire construct. At this time there is no definitive evidence that either method is superior to the other. When screw fixation is utilized, a 3.5-4.5mm screw is placed across the tibio-fibular joint, essentially reinforcing their syndesmosis.
Typically, 2 screws are utilized, and they placed through both bones of the lower leg. An alternative is suture button or tension wire technology which accomplishes the same goal of re-enforcing the syndesmosis. In this technique, instead of utilizing screws, the surgeon uses a high-tension wire which spans the joint and is fixed to the bone on either side with a small button or some other method of fixation.
Open Reduction Internal Fixation of the Syndesmosis
For syndesmosis injuries that ae severe or are identified in association with an ankle fracture, a procedure must be performed to stabilize the syndesmosis and prevent further displacement and instability about the ankle. In this situation, open reduction and internal fixation if the syndesmosis is the preferred operative treatment. This procedure consists of making an incision at the outer aspect of the ankle overlying the fibula. If there is a fracture in this are then it is reduced and fixed in place with a plate and screws. Once the fracture is stabilized, or if there was no fracture, the fibula is then manipulated utilizing clamps or other reduction maneuvers until it is adequately reduced to the native anatomic location. This position is verified using intra-operative x-rays or fluoroscopy and then the bone is fixed in place.
A syndesmosis injury is also known as a “high ankle sprain” and is seen commonly in high impact sports. The injury occurs in 0.5% of all ankle sprains and 13% of all ankle fractures. The syndesmosis is a complex grouping of ligaments present just above the ankle joint which functions to stabilize the ankle and attach the tibia or skin bone to the fibula, which is the smaller bone on the outside of the leg. Injury to the syndesmosis occurs commonly due to rotational injuries about the ankle and when it is injured, the ankle may become unstable. In these instances, if not identified and treated, progressive ankle instability can occur which can lead to poor outcomes with chronic loss of function and pain at the ankle. Minor injuries to the syndesmosis can be treated without surgery, but more major injuries and those that are associated with an ankle fracture must be treated operatively.
The Invisiknot Ankle Syndesmosis Repair KitTM from Smith and Nephew is an innovative system designed for syndesmosis repair in the setting of an ankle fracture or fracture of the distal fibula, or for isolated syndesmotic injuries. The system is designed to eliminate complications associated with rigid screw fixation. Invisiknot is comprised of a suture tape/button construct which includes two stainless steel buttons, one medial or at the inner ankle, and one lateral at the outer ankle. These buttons are connected by ULTRATAPE suture which is a patented braided cord suture. The system is designed to allow for easy reduction of the displaced syndesmosis and tibio-fibular joint with a one-way sliding knot. Additionally, the lateral button is designed to fit perfectly within the 3.5mm holes of a Smith and Nephew distal fibula plate which could be utilized to fix an associated ankle fracture. This design allows for micromotion between the tibia and fibula which again attempts to eliminate some of the complications that are often seen with rigid screw fixation, primarily hardware failure or screw breakage.