Tese de Doutoramento Medicina 2024 Faculdade de Ciências Médicas, Universidade NOVA de Lisboa

Abstract This thesis focus on lateral ankle sprains and instability. Specifically, we propose to review the literature and bring new data on the diagnosis of lateral ankle ligaments’ rupture and on the quantification of the resulting instability. We also address the ideal clinical approach by reviewing the best scientific evidence for the prognosis and by proposing a new classification system for ankle sprains. This document consists of four Parts and eleven Chapters which cover our research in the fields of lateral ankle instability. In Part I we address the scientific evidence on the diagnosis of lateral ankle ligaments’ rupture and rotational ankle instability as well as the clinical presentation and imaging on lateral ankle instability. We discuss its advantages and limitations, analyze the literature comparing surgical procedures with a glance at the most widely used imaging modalities (Chapter I). The concept of rotational ankle instability is described. It is the game-changer in the interpretation of the three-dimensional instability vector resulting from lateral ankle ligaments insufficiency (Chapter II). We then performed an original computational study analyzing the cartilage load pattern after lateral ligament section under an internal rotational load that replicates an ankle rotational instability (Chapter III). In Part II we focus on the quantification of lateral ankle ligament’s laxity in the context of clinical instability. We perform a systematic review of in vivo studies on arthrometerassisted ankle joint stress testing (Chapter IV). We describe an original device based on biomedical gyroscopes. We report on an experimental study on the laxity evaluation with progressive sectioning of lateral ankle ligaments when under strict gravity stress (Chapter V). In Part III we address the prognosis of lateral ankle sprains. We present an original narrative review on the prognosis of lateral ankle sprains, namely in the impact of associated lesions of the anterior talofibular and calcaneofibular ligaments. With this review we intent to deconstruct a myth in the medical literature based on several citation of a personal interpretation (Chapter VI). We also perform a systematic review on the prognosis of ankle sprains regarding the number of ruptured ligaments (Chapter VII). In Part IV we address the classification systems for lateral ankle sprains. We describe a systematic review on acute lateral ankle injury classification systems (Chapter VIII). Finally, we present a new classification for lateral ankle sprains based exclusively on clinical criteria, the Consecutive Ankle Sprain Classification and Injury Systematization. This classification is based on the gait analysis, inspection, palpation and stress testing (Chapter IX). It assists in the deep understanding of the injury pattern and showed prognostic value. The results coming out of the aforementioned chapters are summarized in PART V, presenting a general synthesis, discussing the results according to the published scientific literature and, last but not least, detailing the conclusions of this thesis. In brief, this thesis suggests the following: First, the gold standard for the diagnosis of complete lateral ankle ligaments has continuously shifted over the last decades. Second, the major instability vector after an anterior talofibular ligament rupture occurs in the axial plane, in the internal rotation of the talus around a vertical axis near the medial malleolus. This explains the limited sensitivity of stress imaging using the anterior drawer or varus talar tilt tests. Third, this rotational ankle instability concept, when analysed through a computational study, explains the cartilage injury pattern seen in secondary ankle osteoarthritis due to chronic lateral ankle instability. Fourth, there is high heterogeneity on the laxity outcomes of arthrometer-assisted stress testing using the anterior drawer and talar tilt tests. Fifth, the angular measurement of tibiotalar laxity might be accomplished by our original arthrometer based on gyroscopes. Sixth, most literature reports a similar prognosis between patients with an isolated lesion of the anterior talofibular ligament and those patients with a combined lesion of the anterior talofibular and calcaneofibular ligaments. This belief may be due to the perpetuation of a misinterpretation that took place over several decades ago. Seventh, there is fair evidence showing worse clinical outcome scores and a decreased return to full sports activities in patients who suffered a combined anterior talofibular and calcaneofibular ligaments’ rupture. Eight, there are over two dozen different classification systems for lateral ankle sprains. Nonetheless, most studies still refer to acute sprains using an unspecific classification. None of these systems is used as a reference nor it has prognostic value. Ninth, we propose a new classification, the Consecutive Ankle Sprain Classification, and Injury Systematization (CASCaIS), which proved to be a reliable tool that clinicians can easily use to determine the prognosis of the sprain