Page 36 - ISAKOS 2018 Newsletter Volume 2

CURRENT CONCEPTS
Justification of the
Concept of Microinstability to Explain Anterolateral Impingement Syndrome
Joao Teixeira, MD
Porto, PORTUGAL
Haruki Odagiri MD
Kumamoto, JAPAN
Thomas Bauer MD, PhD
Boulogne, FRANCE
Stéphane Guillo MD,
Bordeaux-Mérignac, FRANCE
The concept of microinstability in the shoulder was described several decades ago, and since then numerous reports have focused on this theme. Microinstability of the shoulder is characterized by shoulder pain or apprehension, secondary to one or more episodes of instability, along with arthroscopic findings showing lesions of the glenohumeral ligament or labrum.
In terms of the ankle, when no mechanical instability is observed following a sprain, we speak of functional instability or anterolateral impingement. Several theories have been proposed on the role of the neurosensitive motor elements in the development of functional instability, but the most recent meta-analysis on this topic demonstrated inconsistencies among these theories1. As in the shoulder, arthroscopic findings naturally led to a search for intra-articular lesions in these patients. Two studies have specifically investigated this topic.
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In 2008, Takao et al.2 reported on 14 patients with functional instability; of these, 9 had partial fibrosis of the anterior talofibular ligament (ATFL), 3 had total fibrosis, and 2 had an avulsion. In 2016, Vega et al.3 reported on 36 patients with functional instability and anterolateral pain secondary to an ankle sprain. Those authors found synovitis in only one patient out of two, a proximal detachment of the ligament in 60% of the cases and a fibrosis of the ATFL in 50% of the cases.
Wollin first described anterolateral ankle impingement in 1950, proposing that this condition was the result of a “mass of connective tissue associated to the ATFL that invades the articular joint space.” The most contemporary description of anterolateral impingement was proposed in 1991 by Ferkel et al.4 (Fig. 1). According to those authors, the initial traumatic event in the development of ankle impingement is an ankle sprain with involvement of the ATFL. Incomplete ligament scarring following the initial event will lead, to either synovitis, orfibrosis, resulting in hypertrophic tissue. This hypertrophic tissue is responsible for the impingement and lateral gutter pain. It appears that history has only retained hypertrophy of the synovium from that description, as subsequent studies (including those by Liu [1994], with 87% good results; Branca [1997], with 63% good results; Kim [2000], with 94% good results, Rasmusen [2002], with 90% good results, Urguden [2005], with 90% good results; and Brennan [2012], with 83% good results) demonstrated very optimistic results without ever focusing on what Ferkel et al. considered to be the initial trauma mechanism, the ATFL lesion. Moreover, none of those articles included an arthroscopic image of the external gutter with relief of the ATFL (Fig. 2), with published images typically showing only the superolateral corner and distal part of the anterior tibiofibular ligament. In addition, it is often very difficult to tell what was really done during a procedure. For example, in the recent review article by Ross et al.5 on the treatment of anterior impingement, soft-tissue management was not described well, in our opinion.
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