Yes. Although lateral ankle stabilization often focuses on the anterior talofibular ligament, this author contends that the anatomy and mechanical role of the calcaneofibular ligament warrant a closer look when planning optimal repairs.
By Patrick R. Burns, DPM, FACFAS
Ankle instability and its associated injuries are a common set of pathologies foot and ankle specialists see in the office. Approximately 25,000 “ankle sprain” injuries occur every day in the United States with patients seeking treatment.1 While most of these injuries successfully resolve without surgical intervention and most have no long-term sequelae, reports reveal that upward of 25 percent of these injuries become chronically unstable.2,3 Unfortunately, these numbers suggest that there are thousands of more significant injuries, such as cartilage and tendon pathology, occurring every day that may require surgical management.
Ankle sprains may involve injury to any of the ankle ligaments and encompass a broad range of injuries with varying degrees of severity. Accordingly, there is a variety of clinical presentations and variable recoveries.
The lateral ankle sprain is the most common among all varieties of ankle sprains. It typically involves an inversion injury and may affect the lateral ligaments including the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL). When lateral ankle sprains are severe or progress to chronic instability, surgical interventions involve stabilizing one or both of these ligaments. Most commonly, the surgeon repairs the anterior talofibular ligament directly and sometimes augments it with the extensor retinaculum or suture anchors to limit the extent to which the native anterior talofibular ligament can stretch. Repair of the calcaneofibular ligament as a part of a lateral ankle stabilization is much less common and probably leads to undertreatment of the injury. With this in mind, I would to focus this discussion on the lateral ankle sprain and the role of the calcaneofibular ligament.
Understanding The Relevant Anatomy And Function Of The Lateral Ankle Ligaments
To understand the importance of the calcaneofibular ligament in lateral ankle sprains, let us reexamine all of the components of ankle sprains including the anatomy, the mechanism of injury and treatments. Early in our careers, we learn the anatomic location of the lateral ankle ligaments, the strength of the ligaments, the typical injury patterns and which ligaments are most vulnerable to injury. We must reexamine this entire thought process to truly appreciate how to treat and prevent further injury.
Anatomically, the anterior talofibular ligament is a thin and flat, quadrilateral-shaped ligament that extends from the anterior edge of the fibula to the lateral neck of the talus. The calcaneofibular ligament is a thick, oval, cord-like ligament and extends from the distal tip of the fibula to the lateral wall of the calcaneus. The ligaments are oriented approximately 132 degrees to each other.4 Traditional teaching dictates that the primary purpose of the anterior talofibular ligament is to limit or prevent anterior translation of the talus from the tibia.
However, we should remember that inversion injuries are the most common mechanism in ankle sprains. So, if the primary role of the anterior talofibular ligament is to limit anterior translation, why are we spending so much time and effort repairing it for an inversion injury? Is this really addressing injured or faulty inversion mechanics? There are countless articles on anterior talofibular ligament repair and dozens of techniques reported. So are we repairing the wrong ligament?
Conversely, the anatomic location of the calcaneofibular ligament is more mechanically in line with the inversion motion so intuitively, it should be involved in the repair to address inversion issues. If the calcaneofibular ligament’s main role is to limit and restrict ankle inversion, why are we not focusing our efforts toward repairing this ligament?
In a cadaveric study involving eight limbs with intact ligaments, researchers stressed lateral ankle ligaments with anterior drawer and talar tilt tests.5 They performed these maneuvers after sectioning of the anterior talofibular ligament and again after sectioning of the calcaneofibular ligament, which would correlate with the most common first- and second-degree ankle sprains. Application of these stresses occurred with the ankles in 10 degrees of dorsiflexion, in neutral and in 20 degrees of plantarflexion. The study showed the anterior talofibular ligament experienced maximal stress with the foot in plantarflexion while the calcaneofibular ligament was reciprocal to that with maximal stress in dorsiflexion.5
Sectioning of the anterior talofibular ligament showed little change in overall laxity regardless of position but sectioning the calcaneofibular ligament demonstrated a pronounced increase in laxity for all positions tested.5 This suggests foot position affects the length of the ligaments but that the calcaneofibular ligament much more significantly controls overall stability in comparison to the anterior talofibular ligament, although it does provide some support in lateral inversion when the foot is plantarflexed.
Another study in 2016 supported this finding, which suggested the calcaneofibular ligament was the primary restraint to the inversion forces applied to cadaveric models in all positions.3 In fact, the calcaneofibular ligament accounted for up to 70 percent of total ankle joint stability during inversion stresses.3
Why Does Lateral Ankle Stabilization Focus On The Anterior Talofibular Ligament?
Perhaps one reason that surgical interventions focus on the anterior talofibular ligament centers limitations in clinical examination. The anterior talofibular ligament is easy to locate and examine in comparison with the calcaneofibular ligament. Many lateral ankle injuries have a positive anterior drawer sign or dimple with anterior stress translation while stress inversion is a bit more difficult to see clinically, despite the fact that it more closely replicates the actual injury.
In addition, the peroneal tendons directly overlying the calcaneofibular ligament are often painful after an ankle sprain, limiting our evaluation of this ligament. While our training prompts us to test the anterior talofibular ligament with an anterior drawer sign, we are repairing it surgically under the pretext of helping restrict inversion and prevent lateral ankle instability even though studies suggest it likely only helps when the foot is plantarflexed. I think the anterior tibiofibular ligament does have a structural role but that role may not be as significant as our training suggests. However, the anterior talofibular ligament may still have some proprioceptive properties and a chronically torn anterior talofibular ligament can certainly be a source of pain.
Another consideration is the size and strength of the two ligaments. The anterior talofibular ligament is a thin, flat banded ligament in comparison with a much more robust cord-like calcaneofibular ligament. The anterior talofibular ligament clearly plays a role in inversion stability as we see it acutely injured in these patients or thickened in chronic instability. If the anterior talofibular ligament is always injured despite the fact that studies suggest it has much less control over inversion stability than the calcaneofibular ligament, one could argue that it does not have the inherent strength or size to be the primary restraint to inversion and instead acts as a secondary restraint, and assists with proprioception.
The calcaneofibular ligament also crosses the subtalar joint, which aids in inversion stability for the ankle joint and the subtalar joint, which is often neglected. Mittlmeier and Rammelt noted that 25 percent of ankle inversion injuries may have some subtalar injury as well.6 This would suggest that at least some lateral ankle sprain repairs miss or neglect this entity, and that repair of the anterior talofibular ligament alone would have no effect on subtalar joint pathology.
Lastly, the surgical approach and repair of the anterior talofibular ligament is certainly more straightforward in comparison with the calcaneofibular ligament, primarily for the anatomic reasons I have already discussed. The anterior talofibular ligament is much more accessible with it being directly off the anterior edge of the distal fibula and relatively superficial. Surgical repair with augmentation of the anterior talofibular ligament via arthroscopic means shows comparable satisfaction rates to traditional open repair of the anterior talofibular ligament.7 Repair of the calcaneofibular ligament, on the other hand, requires peroneal mobilization with the ligament being a little more difficult to access with it lying deep to the peroneal tendons. In addition, lateral calcaneus access may be necessary if the case requires anchors or augmentation.
Salient Procedure Pearls
My preferred technique is to expose the distal tip of the fibula to visualize the origin of the calcaneofibular ligament. I clear the lateral wall of the calcaneus deep to the peroneal tendons and identify the insertion of the calcaneofibular ligament. I then place an anchor in the tip of the fibula deep to the calcaneofibular ligament origin. Next, I pull two ends of suture tape distal to the lateral wall of the calcaneus. With the foot in neutral, I then apply these two ends in an inverted “V” fashion to help spread the load and support posterior and anterior to the calcaneofibular ligament insertion.
This allows a larger footprint for the tape but also helps to reinforce and augment inversion support for the lateral ankle in all foot positions. Surgeons can affix one leg of the non-absorbable suture tape at the anatomic calcaneofibular ligament insertion on the calcaneus and the other more anterior. Once one has placed both anchors, the surgeon can proceed to perform direct repair of the calcaneofibular ligament. One can then repair the anterior talofibular ligament with anchors or as per surgeon preference. Post-operative care typically includes non-weightbearing for three weeks.
It makes sense that based on limitations in our clinical examination and the ease of an isolated anterior talofibular ligament repair in comparison to an isolated repair? of the calcaneofibular ligament that our treatments would focus on anterior talofibular ligament repair. However, when considering the mechanical role of the calcaneofibular ligament in supporting stability of the ankle and subtalar joints against an inversion injury, it seems reasonable to conclude that we should focus more on the calcaneofibular ligament if we are actually trying to prevent future injuries.
The anterior talofibular ligament is an important structure in lateral ankle instability, particularly in a plantarflexed foot, but it otherwise adds little physical support and probably acts more for proprioception. I typically repair the anterior talofibular ligament as I believe it can be a source of pain but I do not hesitate to address the calcaneofibular ligament with repair and augmentation as it clearly plays a more critical role in providing stability and preventing inversion injuries.
Dr. Burns is an Assistant Professor of Orthopedic Surgery at the University of Pittsburgh School of Medicine.
No. Sharing insights from the literature as well as their experience, these authors maintain that repair of the anterior talofibular ligament alone provides desirable results and avoids potential pitfalls of additional surgical intervention.
By Ryan L. McMillen DPM, FACFAS and Jacob Jones DPM
Instability of the ankle joint is one of the most common pathologies treated by foot and ankle surgeons with approximately one in 10,000 people sustaining an ankle sprain type injury on a daily basis in the United States.1 Approximately 85 percent of these injuries are lateral ankle sprains. In fact, the lateral ankle sprain is the most common injury in sports and accounts for 10 to 30 percent of all sports injuries.2-4
Nearly all lateral ankle injuries involve the anterior talofibular ligament (ATFL) while the calcaneofibular ligament (CFL) is involved in approximately one-third of these injuries and the posterior tibiofibular ligament (PTFL) is rarely injured. While non-surgical intervention is successful in the majority of these injuries, the remaining patients may experience persistent instability requiring surgical intervention.2,3
There are numerous surgical interventions for the treatment of lateral ankle instability. These procedures are either anatomic or non-anatomic repairs. Historically, non-anatomic repairs utilize the peroneal tendons to stabilize the lateral ankle ligament complex and reduce inversion. Unfortunately, these procedures inherently reduced eversion strength as well. More recently, direct anatomic repairs, such as the Brostrom, Brostrom-Gould and modified Brostrom procedures, have become gold standards for lateral ankle instability. In comparison to the historical non-anatomic repairs, these direct anatomic repairs are minimally invasive and biomechanically advantageous.4,5
What Does The Literature Reveal About Lateral Ankle Repair Procedures?
In 1966, Brostrom advocated for direct suture repair of torn ends of the anterior talofibular ligament. He described direct end-to-end repair of the ruptured ligament and reported satisfactory results in 85 percent of his cohort.6 Gould theorized that the integrity of ankle stability depends on the integrity of the anterior talofibular ligament following a study by Seligson in 1978.7 Based on this study, Gould concluded that in order to treat lateral ankle instability, one only needed to treat the tear or laxity at the anterior talofibular ligament. Gould and coworkers subsequently described a modification to the Brostrom procedure in 1980 by augmenting the direct ATFL repair with the lateral talocalcaneal ligament and inferior extensor retinaculum.7 In this study, Gould and colleagues described the repair of both acute and chronic injuries with excellent outcomes. The study authors concluded that the theory regarding the integrity of ankle stability depending solely on the anterior talofibular ligament was correct. By accomplishing direct repair of the anterior talofibular ligament, the authors noted improved mechanical stability of the ankle joint in regard to anterior drawer and talar tilt.7
A study by Okuda and coworkers further confirmed this assertion when they described a novel technique in which they performed anatomic repair of only the anterior talofibular ligament utilizing the palmaris longus tendon as an autograft.8 Based on preoperative physical exam and stress testing, the researchers diagnosed the patients as having either an isolated anterior talofibular ligament tear or combined anterior talofibular ligament and calcaneofibular ligament tears. These preoperative stress tests showed significant differences in talar tilt between the two cohorts in both plantarflexion and dorsiflexion. All patients in the study had identical procedures of isolated anterior talofibular ligament repair with palmaris longus tendon autograft.
The authors reported good or excellent results in all patients with no significant difference between the two groups in terms of instability, recurrent ankle sprains or restrictive range of motion.8 Additionally, postoperative talar tilt tests showed no significant differences between the two cohorts in both plantarflexion and dorsiflexion.8
Furthermore, biomechanical studies indicate that isolated repair of the anterior talofibular ligament provides inherent mechanical stability against inversion equivalent to that of combined anterior talofibular ligament and calcaneofibular ligament repair. In a cadaveric study, Lee and coworkers compared the stability of an isolated anterior talofibular ligament repair to a combined anterior talofibular ligament and calcaneofibular repair, and found no significant difference in anterior drawer or talar tilt in the two cohorts.9 Lee and colleagues followed this study with a long-term evaluation of a modified Brostrom procedure without CFL repair.10 With an average follow-up greater than 10 years, they found that 93 percent of their patients had good or excellent results. They also noted no statistically significant difference in anterior drawer or talar tilt in comparison to the contralateral limb at the final follow-up.10
A Closer Look At Surgical Planning And Downsides To Calcaneofibular Ligament Repair
Additionally, repair of the calcaneofibular ligament may inadvertently cause restrictive motion of the ankle and subtalar joints. Numerous biomechanical studies indicate that repair of both the anterior talofibular ligament and calcaneofibular ligament through historical procedures and direct repair result in significant restriction in motion in comparison to that of the intact ankle.3,11
When considering surgical intervention for lateral ankle instability, one must consider the etiology and concomitant pathology. As we previously stated, the anterior talofibular ligament is the most commonly involved ligament in lateral ankle injuries followed by the calcaneofibular ligament and lastly by the posterior tibiofibular ligament.
Other pathologies to consider are osteochondral lesions and peroneal tendon pathology. One may employ advanced imaging to evaluate for such concomitant pathology but this imaging may of less value in determining whether the calcaneofibular ligament is part of the injury.
This is because the literature shows us that whether we are treating an isolated anterior talofibular ligament injury or combined anterior talofibular ligament and calcaneofibular ligament injury, our surgical treatment should remain the same. Direct anatomic repair of the anterior talofibular ligament through a Brostom or modified Brostrom procedure provides equivalent stability, and reduced risk of recurrent injury without restricting motion.4-11 Multiple studies show good and excellent results in both the short- and long-term follow-up of patients having direct anatomic repair of the anterior talofibular ligament.5,8,10
The literature suggests that we are able to provide equivalent outcomes in regard to ankle stability and function with an isolated anterior talofibular ligament repair in comparison to combined anterior talofibular ligament and calcaneofibular ligament repair. When performing an isolated anterior talofibular ligament repair, we provide stability and function that approach that of an intact lateral ankle complex while minimizing invasiveness, and reducing operative time and risk of restrictive range of motion. It is for those reasons and the results of the aforementioned studies that we argue that repair of the calcaneofibular ligament is unnecessary.
Dr. McMillen is Chief of Podiatry at the Allegheny Health Network/Jefferson Hospital in Pittsburgh, Pa. He is board-certified by the American Board of Foot and Ankle Surgery.
Dr. Jones is a second-year resident at the Allegheny Health Network/West Penn Hospital Foot and Ankle Surgical Residency Program in Pittsburgh, Pa.
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10. Lee KT, Park YU, Kim JS, Kim JB, Kim KC, Kang SK. Long-term results after modified Brostrom procedure without calcaneofibular ligament reconstruction. Foot Ankle Int. 2011;32(2)153-157.
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