Establishment of a finite element model of supination-external rotation ankle joint injury and its mechanical analysis

Abstract

By establishing a three-dimensional finite element model of ankle injury arising from supination and external rotation, the stress characteristics of the posterior malleolar surface can be obtained, and analysis of the corresponding stress on the lateral ankle can be conducted. Thin-layer computed tomography images of normal ankle joint in the supination and external rotation nonweight-bearing states was selected, to construct a three-dimensional data model of each ankle joint. A load was applied to examine different ankle joint stress values and pressure distributions on the surface of the posterior ankle joint. A 600 N vertical compressive and 10 Nm internal rotation load was applied in Stage III (removing the anterior tibiofibular ligament and the posterior tibiofibular ligament) of SER (supination-external rotation). When the lateral malleolar was intact, the maximum stress (132.7 MPa) was located at the point of attachment of the posterior tibiofibular ligament to the fibula, and the maximum pressure of the posterior malleolar surface was lower than 4.505 MPa. When a lateral malleolar fracture was present, the maximum stress (82.72 MPa) was located on the fibular fracture surface, and the maximum pressure of the posterior malleolar surface was 8.022 MPa. This study shows that reconstruction of the lateral malleolus in supination-external rotation ankle injuries significantly affects the stress distribution at the posterior malleolar joint surface. Through this reconstruction, the pressure distribution of the posterior malleolar joint surface can be significantly reduced.

Bilateral simultaneous rotational ankle fractures: case series and literature review

“…13 It is originally described that SER IV and PER IV are different from each other in terms of level of fractured fibula being low in SER and higher in PER. [1][2][3] Haraguchi et al found in their biomechanical study that low fibular fracture can be found in reproduced PER mechanism on cadavers. 18 this could explain the fracture in Case 4 since in the left side, the fibular fracture is low, while high on the contralateral side.…”

“…Pronation external rotation or supination external rotation injuries are believed to be causing Maisonneuve fracture except that a classical Maisonneuve injury is a deltoid ligament injury with an associated syndesmotic and proximal fibular fracture. 2 Similarly, syndesmotic injury also known as high ankle sprain is known to be caused by External rotation moment of the dorsiflexed foot. 20 Dienstknecht et al reported a case in which a bilateral Maisonneuve fracture was sustained in an elderly patient by a low mechanism fall.…”

“…1 It showed great reproducibility and interobserver agreement in a recent report. 2 While others found some downsides of its use, the classification's most important attribute is that it helps recognizing the mechanism of injury and associated nonosseus injuries that cannot be seen on plain films. [1][2][3] Injury mechanisms commonly reported according to the classification are supination external rotation (SER), pronation external rotation (PER), supination adduction (SAD), and lasty pronation abduction (PA).…”

“…2 While others found some downsides of its use, the classification's most important attribute is that it helps recognizing the mechanism of injury and associated nonosseus injuries that cannot be seen on plain films. [1][2][3] Injury mechanisms commonly reported according to the classification are supination external rotation (SER), pronation external rotation (PER), supination adduction (SAD), and lasty pronation abduction (PA). For instance, SER starts with anterior inferior tibiofibular ligamentous (AITFL) or boney failure (stage I) followed by a short oblique infrasyndosmotic lateral malleolus fracture or anterior talofibular ligament (ATFL) injury (stage II) followed by posterior inferior tibiofibular ligament (PITFL) or boney failure (stage III) followed by lastly, a medial malleolar or deltoid ligament injury (Stage IV).…”

“…PA injuries start with medial malleolus fracture or deltoid ligament rupture as result of the pronation moment of the talus (stage I), with continued forces, syndesmotic disruption or posterior malleolus fracture happens (stage II), lastly, a bending force occur as the moment continues on the fibula leading to a transverse or a comminuted suprasyndesmotic fracture (stage III). 2,4,5 In axial type ankle injuries such as Pilon and calcaneus fractures, bilaterality has been reported in literature due to the nature of injury mechanism that commonly happens as a result from fall from heights and landing on both extremities simultanously. 6,7 Rotational injuries however tend to happen as a result of sudden catching, twisting or pivoting movement over the supporting leg.…”