Syndesmotic Internal BraceTM for anatomic distal tibiofibular ligament augmentation

Abstract

Reconstruction of unstable syndesmotic injuries is not trivial, and there is no generally accepted treatment guidelines. Thus, there still remain considerable controversies regarding diagnosis, classification and treatment of syndesmotic injuries. Syndesmotic malreduction is the most common indication for early re-operation after ankle fracture surgery, and widening of the ankle mortise by only 1 mm decreases the contact area of the tibiotalar joint by 42%. Outcome of ankle fractures with syndesmosis injury is worse than without, even after surgical syndesmotic stabilization. This may be due to a high incidence of syndesmotic malreduction revealed by increasing postoperative computed tomography controls. Therefore, even open visualization of the syndesmosis during the reduction maneuver has been recommended. Thus, the most important clinical predictor of outcome is consistently reported as accuracy of anatomic reduction of the injured syndesmosis. In this context the TightRope^® system is reported to have advantages compared to classical syndesmotic screws. However, rotational instability of the distal fibula cannot be safely limited by use of 1 or even 2 TightRopes^®. Therefore, we developed a new syndesmotic InternalBrace^TM technique for improved anatomic distal tibiofibular ligament augmentation to protect healing of the injured native ligaments. The InternalBrace^TM technique was developed by Gordon Mackay from Scotland in 2012 using SwiveLocks^® for knotless aperture fixation of a FiberTape^® at the anatomic footprints of the augmented ligaments, and augmentation of the anterior talofibular ligament, the deltoid ligament, the spring ligament and the medial collateral ligaments of the knee have been published so far. According to the individual injury pattern, patients can either be treated by the new syndesmotic InternalBrace^TM technique alone as a single anterior stabilization, or in combination with one posteriorly directed TightRope^® as a double stabilization, or in combination with one TightRope^® and a posterolateral malleolar screw fixation as a triple stabilization. Moreover, the syndesmotic InternalBrace^TM technique is suitable for anatomic refixation of displaced bony avulsion fragments too small for screw fixation and for indirect reduction of small posterolateral tibial avulsion fragments by anatomic reduction of the anterior syndesmosis with an InternalBrace^TM after osteosynthesis of the distal fibula. In this paper, comprehensively illustrated clinical examples show that anatomic reconstruction with rotational stabilization of the syndesmosis can be realized by use of our new syndesmotic InternalBrace^TM technique. A clinical trial for evaluation of the functional outcomes has been started at our hospital.

Keywords: Anatomic repair; InternalBraceTM; Rotational instability; Stabilization; Surgical technique; Syndesmosis injury.

Figure 1

Lateral view on a skeletal model of a left ankle joint: Anatomic augmentation of the anterior and posterior tibiofibular ligament by use of an InternalBraceTM technique is simulated.

Figure 2

Minimally invasive anatomic augmentation of the anterior and posterior syndesmosis in a cadaver model (A-F). Note: The FiberTape^® has to be locked securely inside the bone tunnel of the distal fibula by use of an interference screw to avoid movements of the Tape inside the tunnel with potential sawing effects.

Figure 3

Control of the positioning of the implants by extensive opening of the cadaver situs. View from anterolateral (A) and from posterolateral (B) on a left ankle joint: correct placement of the four anchors for anatomic reduction and augmentation of the anterior and posterior tibiofibular ligament.

Figure 4

Syndesmotic InternalBrace^TM for anterior single stabilization after suturing of the disrupted anterior syndesmotic ligament (A-D).

Figure 5

Syndesmotic InternalBrace^TM for double stabilization by combination with a slightly posteriorly running TightRope^® for indirect reduction (A) and stabilization (B) of the fracture of the posterior malleolus.

Figure 6

Syndesmotic InternalBrace^TM for double stabilization. Comparison of preoperative (A, C, E, G, I) and postoperative (B, D, F, H, J) CT scans. Note: anatomic positioning (F, H) and rotation (J) of the distal fibula and indirect anatomic reduction of the fracture of the posterior malleolus (D, F, H).

Figure 7

Syndesmotic InternalBrace^TM for triple stabilization. The posterior malleolus was first directly refixed with a lag screw (A), then the anterior syndesmosis was augmented with an InternalBraceTM under direct view (B, C), and finally the posterolateral screw fixation was augmented by a slightly posteriorly directed TightRope^® resulting in a perfect anatomical positioning of the highly unstable distal fibula (D).

Figure 8

Trimalleolar dislocation fracture of a right ankle joint (A, B).

Figure 9

Computed tomography scans of the ankle from Figure 8 showing tibial avulsion of the anterior tibiofibular ligament with dislocation of a bone fragment (black arrow) too small for screw fixation (A), complete closed reduction was not possible due to a small bone fragment (white arrow) interposed between distal tibia and fibula (B), displaced avulsion of a small fragment of the posterolateral malleolus (C, D).

Figure 10

Surgical treatment of the patient from Figure 8. Note the small bony tibial avulsion fragment of the anterior tibiofibular ligament (black arrow) and the corresponding avulsion site (white arrow) at the tubercule de Chaput (A). After reduction of the avulsion fragment the whole ligament proved to be intact (B). Insertion of a FiberTape^® about 4 mm proximal and medial of the avulsion site with a 4.75 mm SwiveLock^® (C). Standard osteosynthesis of the distal fibula was performed using an anatomic preformed locking plate (Arthrex^®, Naples, United States). The reduced tibial avulsion fragment was then stabilized with a FiberTape^® fixed by the tibial 4.75 mm SwiveLock^® and by knots under the osteosynthesis plate (D).

Figure 11

Postoperative X-rays of the ankle from Figure 8 showing anatomic reduction of the syndesmotic injury (A, B). The tibial bone tunnel for the InternalBraceTM visible (black arrow).

Figure 12

Postoperative computed tomography scans of the ankle from Figure 8 showing anatomic reduction of the tibial avulsion (white arrows) of the anterior tibiofibular ligament (A, C) as well as anatomic reduction of the ankle mortise (D); the tibial bone tunnel (black arrows) for the InternalBrace^TM is clearly visible (A, B).

Figure 13

Intraoperative testing of syndesmotic stability after distal fibular plating: The classical hook test (A, B) shows no lateral translation of the distal fibula while pulling the distal fibula laterally and pushing the distal tibia medially, indicating a normal result without syndesmotic instability, however, the same ankle joint shows relevant rotational instability of the anterior tibiofibular ligament (C, D) indicating the need for surgical stabilization.

Figure 14

Intraoperative testing of syndesmotic stability after distal fibular plating using a mounted drill bit for locking screws: The ankle joint shows relevant external rotational instability of the anterior tibiofibular ligament (B) indicating the need for surgical stabilization. Note opening (white arrow in B) of the star figure (black arrow in A) normally built by the tibiofibular, tibiotalar and talofibular joint lines by external rotation of the distal fibula (B).

Figure 15

Prototype of a new syndesmosis plate (Arthrex, Naples, United States) with suture holes especially designed for augmentation of the anterior and posterior syndesmosis.

Figure 16

Prototype of a new syndesmosis plate with four suture holes, each combined with a specially designed notch at the inside surface exactly in line with the potential course of the inserted and tensioned FiberTape^®.