Anatomy of the distal tibiofibular syndesmosis in adults: a pictorial essay with a multimodality approach

Abstract

A syndesmosis is defined as a fibrous joint in which two adjacent bones are linked by a strong membrane or ligaments. This definition also applies for the distal tibiofibular syndesmosis, which is a syndesmotic joint formed by two bones and four ligaments. The distal tibia and fibula form the osseous part of the syndesmosis and are linked by the distal anterior tibiofibular ligament, the distal posterior tibiofibular ligament, the transverse ligament and the interosseous ligament. Although the syndesmosis is a joint, in the literature the term syndesmotic injury is used to describe injury of the syndesmotic ligaments. In an estimated 1-11% of all ankle sprains, injury of the distal tibiofibular syndesmosis occurs. Forty percent of patients still have complaints of ankle instability 6 months after an ankle sprain. This could be due to widening of the ankle mortise as a result of increased length of the syndesmotic ligaments after acute ankle sprain. As widening of the ankle mortise by 1 mm decreases the contact area of the tibiotalar joint by 42%, this could lead to instability and hence early osteoarthritis of the tibiotalar joint. In fractures of the ankle, syndesmotic injury occurs in about 50% of type Weber B and in all of type Weber C fractures. However, in discussing syndesmotic injury, it seems the exact proximal and distal boundaries of the distal tibiofibular syndesmosis are not well defined. There is no clear statement in the Ashhurst and Bromer etiological, the LaugeHansen genetic or the Danis-Weber topographical fracture classification about the exact extent of the syndesmosis. This joint is also not clearly defined in anatomical textbooks, such as Lanz and Wachsmuth. Kelikian and Kelikian postulate that the distal tibiofibular joint begins at the level of origin of the tibiofibular ligaments from the tibia and ends where these ligaments insert into the fibular malleolus. As the syndesmosis of the ankle plays an important role in the stability of the talocrural joint, understanding of the exact anatomy of both the osseous and ligamentous structures is essential in interpreting plain radiographs, CT and MR images, in ankle arthroscopy and in therapeutic management. With this pictorial essay we try to fill the hiatus in anatomic knowledge and provide a detailed anatomic description of the syndesmotic bones with the incisura fibularis, the syndesmotic recess, synovial fold and tibiofibular contact zone and the four syndesmotic ligaments. Each section describes a separate syndesmotic structure, followed by its clinical relevance and discussion of remaining questions.

Biomechanical comparison of bionic, screw and Endobutton fixation in the treatment of tibiofibular syndesmosis injuries

“…This distal tibiofibular syndesmosis is a delicate structure which comprises two bones and four ligaments; the distal tibia and fibula form the osseous part and are linked by the distal anterior tibiofibular ligament, the distal posterior tibiofibular ligament, the transverse ligament and the interosseous ligament [18]. It enables the tibia and fibula to move in a dynamic relationship during ankle motion [19,20], and some researchers have argued that the connection of the distal tibia and fibula is not a mere syndesmosis but also a synovial joint [16].…”

Complications in ankle fracture surgery

“…The four main ligaments that contribute to the syndesmotic complex are the anterior tibiofibular ligament (ATFL), the posterior tibiofibular ligament (PTFL), the transverse ligament, and the interosseous ligament (Hermans et al 2010). The PTFL is the strongest part of the syndesmosis, and together with the associated transverse ligament it provides 42% of the overall syndesmotic resistance strength (Ogilvie- Harris et al 1994).…”

Syndesmotic Injuries in Athletes

“…This ligament has a width of approximately 18mm, length between 20 and 30mm, and a thickness of 2 to 4 mm. It is the most commonly sprained ligament in syndesmotic injuries and is always disrupted with joint space widening or frank diastasis [15]. It is often multifascicular, and its most inferior fascicle has been described as a discrete structure called the accessory AITF ligament.…”

“…Its depth varies from 1.0 to 7.5mm [19,20] and is a little less in women than in men [21]. A shallow notch may predispose to recurrent ankle sprains or syndesmotic injury with fracture-dislocation [15] The bony architecture of the fibula mirrors that of the fibular notch. The medial aspect of the fibula forms a convex structure that complements that of the tibia, with an anterior and posterior margin, as well as a ridge that bifurcates that margins and aligns itself with the incisura tibialis.…”