According to the guidelines of human anatomy, the ligaments in the ankle are grouped structured by two ligament complexes: the lateral collateral ligament and the medial or deltoid collateral ligament. In a new scientific study, the University of Barcelona (UB) research team defined a new anatomic structure in the ankle, the lateral fibulotalocal caneal ligament complex (LFTCL).
Describing this anatomic structure is now possible thanks to the analysis of fibres that link two of the lateral collateral ligament compounds.Also, for the first time, they describe one of the parts in this new structure as intra-articular. These results, published in the scientific journal KneeSurgery, Sports Traumatology, Arthroscopy, change the understanding of this joint and could explain why many ankle injuries produce chronic pain.
Ankle lateral ligaments receive more injuries in the human body, with many people who suffer from this injury complaining about pain in the ankle which lingers, and which was difficult to explain.
“This lack of explanation was the key to change the way to tackle ligament dissection in the dissection room and we saw linking fibres between ligaments were usually removed because they were not associated with the ligament,” said Miquel Dalmau Pastor, researcher at UB.
According to the new study, these fibres link the inferior fascicle (set of ligamentous fibres) in the anterior talo fibular ligament and the calcaneofibular ligament, two out of the three components in the lateral collateral ligament. “This connection was never described, and contrary to what was thought, it suggests that both ligaments are a functional unit. That is, we could consider these two connected ligaments as an anatomic structure we call lateral fibulotalocal caneal ligament complex,” said Dalmau Pastor.
This description of the ligament fits with some clinical publications,which showed the good results of isolated repair of the anterior talofibular ligament in cases of injuries of the anterior talo fibular ligament and calcaneofibular ligament.
“These publications made us think that perhaps the calcaneofibular ligament could be repaired by repairing the anterior talofibular ligament, and this could only happen if there was some kind of connection between ligaments,”noted Jordi Vega.
The careful dissection of the articular capsule in the ankle enabled researchers to identify the intra-articular compound in the anterior talofibular ligament. According to the study, this ligament would be built by two fascicles, the superior and inferior one, where the superior fascicle lies within the joint and the inferior one is outside. This inferior fascicle,together with the calcaneo fibular ligament and fibres would form the fibulotalocalcaneal lateral complex, which would then be an extra-articular structure.
Describing that part of the anterior talofibular ligament is an intra-articular structure could have implications in the evolution and treatment of this kind of injuries.
“These findings suggest the behaviour after an injury will be similar to the other intra-articular ligaments, such as the twill, which are not able to cicatrise, and this makes the joint remain unstable and in many cases it requires a surgical operation,” said Miquel Dalmau-Pastor.
These results would explain why many sprains cause pain after the patient follows the treatment the doctor suggests. “Since the intra-articular ligament does not cicatrise, the instability of the joint produces pain so these patients are likely to suffer from another sprain and develop other injuries in the ankle,” highlighted Francesc Malagelada.
Apart from the anatomic observation in the dissections carried out at the University of Barcelona, the researchers studied the behaviour of ligaments.
“The superior fascicle in the anterior talo fibular ligament, apart from being intra-articular, is not an isometric structure – that is, it relaxes when the foot is on a dorsal flexion, and it tenses when it is on a plantar flexion.However, the inferior fascicle, the arciform fibres and the calcaneofibular ligament, the described ligament complex, are extra-articular structures and are isometric, so that they are always taut,” concluded Maria Cristina Manzanares.
Source: University of Barcelona
Reference: Jordi Vega, and others. The lateral fibulotalocalcaneal ligament complex: an ankle stabilizing isometricstructure. Knee Surgery, Sports Traumatology, Arthroscopy, 2018;DOI: 10.1007/s00167-018-5188-8