Whether it’s the star quarterback at Alabama, an NBA player with a high ankle sprain or a military recruit getting hurt on an obstacle course during basic training, it appears that syndesmosis injuries are pervasive. The number of syndesmosis videos on YouTube is astounding. When ESPN hosts medical segments to explain the use of TightRope products (Arthrex) and syndesmotic screws, the topic of syndesmosis injuries has clearly entered the lexicon of society.
Fifteen years ago, the whole topic of high ankle sprains seemed more mysterious. Then Terrell Owens, playing for the Philadelphia Eagles at the time, underwent a syndesmosis repair for a Maisonneuve fracture seven weeks before the Super Bowl in 2005. As the Eagles kept winning, he kept training. He defied literally all his doctors and football analysts alike by not only playing in the Super Bowl but playing extremely well. Years later, we now see football players routinely competing three to four weeks after a syndesmosis repair. Tua Tagovailoa, quarterback for the Alabama Crimson Tide, sustained one syndesmosis injury after another in two consecutive seasons and played only weeks after each surgery. (See “What Studies Reveal About The Prevalence Of Syndesmosis Injuries In Sports” at right.)
Despite the buzz around syndesmosis injuries, they are really uncommon as isolated ligamentous injuries. Upon reviewing the past 10 years of syndesmosis repairs performed at the General Leonard Wood Army Community Hospital in Ft. Leonard Wood, Mo., only a small fraction were purely ligamentous. For the sake of simplicity, I would like to focus this column on syndesmosis injuries without fracture. Essentially, I am referring to purely ligamentous injuries. Amazingly, most of us will see more articles published on the topic than actual pathology in our practice. In my experience, this injury is often misdiagnosed or over-treated.
Within our military practice at Ft. Leonard Wood, Mo., we average over 1,000 ankle sprains a year. Less than 100 of them are syndesmosis injuries and less than 20 require syndesmosis repair. In my experience, discussing what ligament or ligaments are injured is far more important than trying to grade the injury. Grading is simple. The injury is either stable or unstable. This eliminates subjectivity.
While practicing in Ft. Bragg, N.C., we averaged 4,000 ankle sprains per year. There was no time to grade anything with those kind of numbers. Syndesmosis injuries are best defined, in my experience, as injuries to the anterior inferior tibiofibular ligament, posterior inferior tibiofibular ligament and/or tear of the interosseous membrane with or without Chaput, Wagstaffe or posterior malleolar avulsions. Depending on the injury pattern, determining the severity and stability creates much confusion and argument.5
Emphasizing A Thorough Diagnostic Workup
Making the diagnosis of a syndesmosis injury requires not just an X-ray but a thorough exam. We often forget that pain and swelling about the syndesmosis is pretty simple to define: a positive squeeze test, pain with external rotation and, more often, significant pain with weightbearing activity. These findings are all crucial but are still not conclusive. Some injuries are more obvious than others. (See image to the right.)
Significant research has involved advanced imaging from computed tomography (CT) to magnetic resonance imaging (MRI). However, if the syndesmosis and mortise are aligned, then everything hinges on a stress exam under fluoroscopy or X-ray.6-8
Unfortunately, there is often considerable debate on what an unstable syndesmosis looks like. In their 2018 intra-observer study, Naguib and Meyr saw mixed results and concluded that “the reliability was well below what would be expected of a gold standard test during stress examination of the ankle syndesmosis.”9 This is no surprise to me. Junior colleagues over the years, after performing stress X-rays, have concluded that a syndesmosis was unstable despite not seeing any measurable difference in the syndesmotic space between non-stress and stress views. Even worse, I have also heard of surgeons simply taking a patient to the operating room and putting a couple of screws in without ever stressing the ankle.
To complicate matters, surgeons must recognize the difference between syndesmosis instability and mortise widening. Too often, surgeons mistake syndesmosis instability for deltoid instability. Syndesmosis instability can appear in many ways. We may simply see a rotation of the fibula depending on which ligament is injured. Either scenario will have a different presentation upon stress exam or only be visible on CT or MRI with coronal views. One must be able to interpret all the imaging to make appropriate surgical decisions. Too often, surgeons may take the “when in doubt” approach and fix any and all potential syndesmosis injuries regardless of stability.
Is Arthroscopic Evaluation Worthwhile?
To further complicate diagnostic modalities, we have seen a growing use of arthroscopic evaluation for the grading of syndesmosis injuries. In a 2016 study, Calder and colleagues utilized arthroscopy to assess the damage associated with unstable syndesmosis injuries in 28 athletes.10 Turky and coworkers performed 78 diagnostic arthroscopies to assess syndesmosis stability in 2018.11 Unfortunately, these authors mixed acute and chronic syndesmosis injuries together. I have performed a number of arthroscopic assessments for chronic syndesmosis issues but I really have not explored acute injuries unless they involved acute talar dome or Chaput fractures.
Regardless, arthroscopic evaluation is a very simple way to assess pathology but it cannot replace a proper stress exam (see images to right). Numerous videos on the Internet show arthroscopic reduction of the syndesmosis with a large fracture clamp. While you can see the tibiofibular space close down after use of the fracture clamp, without the C-arm view, it is still very difficult to assess how much is enough arthroscopically. It is not the same as reducing a fracture arthroscopically. An arthroscopic view is not conclusive in determining appropriate reduction. One can only do this with intra-operative C-arm radiographic views.
What Is The Optimal Fixation For These Injuries?
While determining the need for surgery should be simple, deciding on optimal fixation is more challenging as more and more companies are producing EndoButton (Smith & Nephew)-like options to compete with the TightRope. Even Arthrex has modified and improved its products as other companies introduce their own implants. One major improvement is the knotless feature. For purely ligamentous injuries, the EndoButton and TightRope modalities appear to be the emerging fixation of choice of surgeons in both sports medicine and the military.8,10,12
The technique for the EndoButton modality is simple. After reducing the syndesmosis with a large fracture reduction clamp, pre-drill with the prepacked drill bit. Slide the EndoButton into place. Ensure the far side button has flipped into place and catches on the tibia. Tighten the suture button down until it is snug. Please make sure you pay attention as to whether your EndoButton kit is knotless or requires tying in place. Throughout the procedure, leave the fracture clamp in place. If a second EndoButton is necessary, repeat the previous steps. As long as the syndesmosis is stable upon removal of the clamp, the procedure is complete (see images to right).
As with any technique and fixation device, there will be those who believe that screws are always going to be superior, but screw fixation may or may not require removal. Similarly, some surgeons will attest that the EndoButtons are not foolproof. On occasion, I have seen this fixation loosen with time and lose reduction. Saphenous nerve irritation related to the button is also possible.
To combat those issues, some surgeons have considered changing up the technique by using an alternate fixation system. The Arthrex TightRope FT system utilizes a 4.5 mm bio-corkscrew instead of an EndoButton. With this system, one relies on the cortical purchase of the lateral cortex of the tibia instead of drilling through the tibia to the medial side. This avoids any potential saphenous nerve irritation or a need to remove the button in the future (see image to right).
Assessing Key Factors That Affect Return To Activity
As with any athlete or soldier, the focus soon turns to return to activity. Numerous studies have looked at post-op protocols for timing to return to sport. Ultimately, success and timing seem less dependent on the surgery than on the original injury. Bone bruising patterns and the number of involved ligaments have more importance than surgeons would like to admit.
In a 2016 study, Shawen and colleagues suggested that history of previous injuries, level of proprioception and the level of confidence postoperatively were far more crucial to recovery than the repair itself.13 An MRI study involving NFL football players in 2012 concluded that MRIs were not helpful in predicting return or even recovery times.6 The study authors also noted that the severity of ligamentous and syndesmotic disruption on MRI did not correlate to recovery times. Another study out of the University of Michigan in 2012 suggested that at least among college football players, a player’s position played a far greater role in how soon a player could return to practice and games.7
Anecdotally, I would attest that weight has played a huge role in the ability of my athletic and military patients to return to competition or full activity. It could be an NFL lineman topping out at 320 pounds or an 82nd Airborne paratrooper, weighing 250 pounds, who needs to be able to wear a 200-pound rucksack. One cannot properly compare these patients to a 150-pound cross country runner. Regardless of activity level, in my experience, lighter patients return to their desired sport or activity faster.
I also believe foot type plays a significant role in recovering from an syndesmosis injury, especially in lieu of a deltoid injury. Patients with severe pes planus who have had deltoid injuries will often struggle to return to activity and are at a significant risk of re-injury and developing chronic pain. These individuals routinely take far longer to return to sport than a patient with the same characteristics but a normal arch.
Syndesmosis injury without fracture is very uncommon in the general population but athletes are prone to these injuries. A majority of athletes with these injuries will present with a stable mortise and syndesmosis, at least on imaging. It is critical that surgeons recognize the need for stress examination. Failure to recognize these injuries is just as detrimental to the health of the ankle as a missed Maisonneuve fracture. The use of EndoButton and TightRope fixation has revolutionized our treatment of syndesmosis injuries with and without fracture. Screw fixation is also available and may always be the gold standard, but in my experience, nothing gets athletes back into the game faster than the use of EndoButton-style repair.
Dr. Spitalny is a staff podiatrist at the General Leonard Wood Army Community Hospital in Ft. Leonard Wood, MO, and adjunct faculty with the DePaul Podiatric Surgical Residency Program in St. Louis.
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