الفهرس 
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Abstract
The ankle is commonly injured in the athletic population. One of the important affection is the high ankle sprain or syndesmotic sprain. The syndesmotic sprain is similar to ankle sprain injury in comparison with the lateral ankle sprain. Syndesmotic injuries involve disruption of the ligamentous structures between the distal fibula and tibia just proximal to the ankle joint. Disruption of the syndesmosis following an ankle fracture is common and usually the result of an external rotation injury, while pure syndesmotic injury is less common.
The distal syndesmotic articulation between the tibia and fibula is comprised of 3 major ligaments: the anterior inferior tibiofibular ligament (AITFL), the posterior inferior tibiofibular ligament (PITFL), and the interosseous ligament. These ligaments provide such strong stabilization to the articulation that the fibula only rotates externally up to 2° relative to the tibia, and the ankle mortise widens only about 1 mm as the intact ankle joint moves from full plantar flexion to full dorsiflexion. These ligaments stabilize the ankle mortise by providing strong opposition of the fibula to the fibular notch of the tibia, and by providing strong dynamic support to the ankle mortise of the syndesmotic ligaments. The AITFL and PITFL are considered the primary stabilizers of the distal tibiofibular articulation. Ankle syndesmotic injury does not necessarily lead to ankle instability, however, the coexistence of deltoid ligament injury critically destabilize the ankle joint, the syndesmotic injuries may involve the distal tibiofibular syndesmosis and can be associated with a variable degree of trauma to the soft tissue and/or osseous structures that play an important role in ankle joint stability.
Over 90% of the total resistance to lateral displacement of the fibula is provided by the three syndesmotic ligaments, and injury to one or more of them results in weakening, abnormal movement of the joint and instability. Although many mechanisms for syndesmotic injury have been reported, the most common is external rotation of the foot and to a lesser extent forced dorsiflexion of the ankle with axial loading. Other causes include eversion, inversion, plantar flexion, pronalion and internal rotation. The diagnosis of syndesmotic injury may not be a straight forward, in the absence of fracture; physical examination findings suggestive of injury include ankle tenderness over the anterior aspect of the syndesmosis and a positive squeeze or external rotation tests. Radiographic findings usually include increased tibiofibular clear space, decreased tibiofibular overlap, increased medial clear space, and other advanced diagnostic modalities include CT and1 MRI. The goal of management is to restore and maintain the normal tibiofibular relationship to allow for healing of the ligamentous structures of the syndesmosis. Non-surgical management is indicated when the syndesmotic sprain is not associated with diastasis or instability, or when restoration of the proper tibio-fibular relationship and accurate restoration of the fibular length is achieved with open reduction and stable fixation of the fibular fracture. Non-surgical treatment begins with rest, ice, compression and elevation. Subsequently, a non weight bearing cast is used for 2 to 3 weeks followed by progressive weight bearing as tolerated.
Fixation of the syndesmosis is indicated when an evidence of a diastasis is present. This may be detected preoperatively, in the absence of fracture, or intra-operatively after fixation of medial malleous and fibular fractures. Syndesmotic injury can be controlled by screw fixation. However, the choice between metal and bioabsorbable screws, screw size, number of cortices fixed, and indications for screw removal remain controversial. Conditions such as diabetes or advanced age are no longer contraindications to usual management recommendations. Syndesmotic screw placement is a common technique for Syndesmotic disruption. The procedure restores stability to the distal tibiofibular joint while allowing ligamentous healing. Although this technique is commonly used, there is a lack of consensus regarding the timing and necessity of screw removal. Most authors suggest that 6 to 12 weeks are required for adequate ligamentous healing to occur. To avoid late instability, some authors have recommended screw removal no earlier than 12 weeks. Additionally, there is lack of consensus for retaining or removing the screw after syndesmotic healing occurs. While some physicians suggest routine removal of all syndesmotic screws, others accept screw failure. Failure to diagnose and stabilize syndesmotic disruption adversely affect outcome. Functional, mechanical instability, or chronic pain, stiffness, and/or edema are the main complication of missed diagnosis and management of this type of injury.
Surgical management may be complicated with failure of reduction due to breakage of the screw or loosening usually in noncompliant patient with weight bearing, another complication include heterotropic calcification which need excision if causing chronic pain. Distal tibial fatigue fracture may complicate syndesmotic fixation and can be detected early if good quality post-operative X-ray obtained with three views (anteroposterior, lateral, and mortise) of all ankle fractures to thoroughly evaluate osseous and ligament anatomy.