Ankylosing spondylitis is a subtype of inflammatory rheumatic disease, predominantly affecting the axial skeleton and sacroiliac joints. Ankylosing spondylitis is associated with inflammation or new bone formation, with syndesmophytes and ankyloses visible on radiographs [1]. The main clinical manifestations are spinal stiffness and inflammatory back pain, which yield adverse effects on work ability, work productivity, quality of life, and psychological well-being [2,3]. Gait ability is known to contribute to functional independence and quality of life in patients with stroke [4,5] or following hip arthroplasty [6] and is impaired in patients with ankylosing spondylitis [7]. Indeed, considering the decreased range of movement, pain, and altered posture [8,9] associated with ankylosing spondylitis, previous works have reported that ankylosing spondylitis leads to more cautious gait pattern, shorter stride length, and decreased range of motion at the hip and knee joints [10-12]. However, it is still unclear whether and how gait is modified in patients with ankylosing spondylitis. Previous studies reported that patients with ankylosing spondylitis covered significantly lesser distance than controls during the Six-Minute Walk test [13] and adopted a shorter stride length [12], whereas in other published studies, no statistically significant group differences were reported for the same gait-related parameters [10,11,14]. Furthermore, published studies showed heterogeneity in terms of task requirement, types of equipment, data collection, and analysis techniques used to assess gait ability of patients with ankylosing spondylitis. For instance, gait-related studies encompass an increasingly large variety of tasks, types of equipment, and analysis techniques including, for example, both clinical (eg, Timed-Up-and-Go test and Six-Minute Walk test) and laboratory measurements (kinetic, kinematic, or electromyographic gait analysis), which should be taken into consideration for the assessment of gait ability in patients with ankylosing spondylitis. Thus, this systematic review aims to document the effect of ankylosing spondylitis in gait, specifically focusing on published studies that have reported clinical or laboratory gait measurements in patients with ankylosing spondylitis. More specifically, this review aimed to determine the consequences of ankylosing spondylitis on gait and how gait is assessed in patients with ankylosing spondylitis.

This protocol has been registered in PROSPERO (CRD42018102540). We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement guidelines provided by Moher et al when conducting our systematic review and meta-analysis [15].

As of September 2018, we have completed the search strategy and obtained 168 records. After screening titles and abstracts, 19 full texts were reviewed. Of those, 17 were included in the review (Figure 1). We are currently in the process of data extraction and synthesis. We expect the final results to be submitted for publication in March 2019.

Considering the importance of gait in functional independence and quality of life, there are a growing number of reviews and reports examining gait characteristics in a wide range of populations [19] with neurological disorders [20-22], hip osteoarthritis [23], diabetes [24], frailty [25], or dementia [26] and in older adults [17]. However, as of September 2018, only one review published in 2015 focused on gait characteristics in rheumatologic patients [7], with only 3 studies reporting results of patients with ankylosing spondylitis [10-12]. Interestingly, the abovementioned review [7] focused on case-control studies only (ie, “studies were included...if they were articles that included a healthy group as means of comparison” [7]). This review did not include studies with clinical measurements of gait, but only studies reporting laboratory measurements (ie, “studies were included...if they reported spatiotemporal, kinematic, kinetic, peak plantar pressure or muscle activity data during gait” [7]). Thus, an update of the published literature is needed.

A strength of this review protocol is that it includes both clinical and laboratory measurements of gait studies on patients with ankylosing spondylitis, reporting precisely the methodology used in each selected study, as recommended by the PRISMA statement (e.g. “how the data was collected and analysed” [15]). Indeed, early identification of gait deficits in patients with ankylosing spondylitis could help us better understand, follow, and predict disease evolution and allow for timely implementation of targeted interventions or treatment to improve gait. Keywords have been chosen based on latest reviews on ankylosing spondylitis [16] and gait [17] separately and were searched in principal databases, assuring the conduct of a systematic review.

However, there are some limitations related to this review that need to be addressed. We assume that the selection and qualitative synthesis of the eligible studies are a subjective process. However, we will seek to minimize this limitation by duplicating our search and having two reviewers conduct the screening process independently [15]. We plan to present the results of this systematic review at international scientific and clinical conferences and publish them in a peer-reviewed scientific journal. The systematic review will provide a synthesis and comprehensive evaluation of published research on gait characteristics in patients with ankylosing spondylitis. Largely, this work is further intended to help identify the likely relevant directions for future research. For instance, from a clinical perspective, we support the idea that an objective and standardized assessment of gait characteristics should be an integral part of every comprehensive assessment of patients with ankylosing spondylitis.