In vivo arthrometer measurements of mechanical ankle instability—A systematic review

Abstract

Chronic ankle instability is caused by functional and/or mechanical deficits. To differentiate the two entities, mechanical ankle instability can be assessed using arthrometers. The measurement of mechanical instability is essential, since it can only be addressed surgically. The aim of this systematic literature review was to find out whether chronic mechanical ankle instability could be adequately and objectively assessed using in vivo arthrometer measurements. Articles were included if the main focus was to evaluate the contribution of mechanical deficits to chronic ankle instability and if they provided sufficient description of the device used. This systematic review was performed according to the PRISMA-recommendations. Initially 47 articles were screened for eligibility, of which 33 studies reporting 10 different devices were included. While the reliability of the measurements was mostly good to excellent, only two studies aimed to assess the sensitivity and specificity of their results in regard to chronic ankle instability. Several devices reported conflicting results about mechanical deficits. In summary, this systematic review reveals a substantial deficit in diagnostic accuracy when assessing mechanical ankle instability in a clinical setting. Biases in recruiting and classification of participants raise the question whether the two entities of functional and mechanical ankle instability are properly defined. Clinical Significance: In recent years, this may have led to a misinterpretation of mechanical deficits and the subsequent need for surgical intervention. ß 2019

Functional deficits in chronic mechanical ankle instability

“…Current literature suggests that a certain degree of mechanical instability cannot be compensated by functional training but may instead require mechanical stabilization [8,23]. Whether an undetermined severity of mechanical insufficiency inevitably leads to an additional perception of instability, according to the model of Hiller et al [24], remains unclear in current literature [4,25].…”

“…Especially in the clinical approach to CAI patients, it is important to distinguish between those suffering from predominantly functional deficits and those patients suffering due to an insufficient mechanical stability [25,26]. Ultimately, it may be suggested that only the latter will benefit from operative stabilization, while the others should be treated conservatively [2,6,27,28].…”

“…As mentioned above, the exact definitions of CAI, FAI, and MAI have been subject to increasing debate in the last decade [29]. It is of note that many earlier studies did not differentiate the patients' mechanical and functional insufficiencies possibly because quantifying mechanical ankle instability remains a diagnostic challenge [25]. At present, the extent to which FAI and MAI interact remains unclear [1,10,24,30].…”

Quantitative analysis with load–displacement ratio measured via digital arthrometer in the diagnostic evaluation of chronic ankle instability: a cross-sectional study

“…Arthrometry has been investigated by a large amount of studies as a method to quantitatively perform ADT and has shown good to excellent effects in differentiating uninjured ankles and ankles with instability [ 12 , 26 – 29 ]. However, even though the amount of studies that reported reliable measures of ankle instability is very high, there are only few groups that assessed or published the clinical application and diagnostic accuracy of the respective measurements in terms of sensitivity and specificity [ 30 ]. Further, the diagnostic accuracy of arthrometers is still debatable because of the diversity in studies regarding selection criteria, arthrometric devices and reference standards.…”

“…Differences in the selection of reference standards also influence diagnostic accuracy of arthrometers. A systemic review of in vivo arthrometer measurements showed that studies regarding diagnostic accuracy of arthrometers in an in vivo, clinical setting were still limited [ 30 ]. In existing literature that calculated diagnostic accuracy (i.e., sensitivity, specificity), researchers chose different reference standards, and the resulting diagnostic accuracy varied greatly.…”