De Quervain’s Tenosynovitis: A Systematic and Citation Network Analysis Review

De Quervain's tenosynovitis (DQV) is a common hand disorder causing pain along the radial side of the wrist in patients...

The occurrence of neutrophil elastase and cyclooxygenase, and the corresponding effects on the collagen structure in the extensor retinaculum samples collected from patients with DQV, indicate the presence of inflammation in the FDC in DQV [4].
However, some studies have mentioned that despite the term 'tenosynovitis' in DQV, there is actually no inflammation involved.
The thickening of the synovial sheath is due to degenerative changes, such as myxoid degeneration [5,6] and may cause the tightening of the tendon canal during movement of the APL and EPB tendons [3,7]. Thus, there is greater friction between the two tendons and the tendon canal, which could produce pain and tenderness over the FDC [1].

Graphical Abstract 1.
The prevalence of DQV is 0.5% in men and 1.3% in women among the general population [5], so women will have DQV more than men [8]. Patients are usually in their forties to sixties [9]. Risk factors include the overuse of the hands, and repetitive hand activities that depend on wrist and thumb movements [10]. Le Manac'h, et al. [11] carried out a study that assessed the occupational risk factors of DQV in French workers such as working tasks that required sustained periods of wrist bending or extreme wrist postures, and repetitive hand movements like driving screws.
Those who are employed in occupations that require repetitive and forceful hand movements, such as musicians and machinists, face an increased risk of DQV. Postpartum women are also at risk of DQV as they are constantly lifting their babies [10]. A number of studies have shown that anatomical variations in the FDC, such as the presence of septum and multiple slips of the tendon are associated with DQV [12,13].
The diagnostic test for DQV is the Finkelstein's test, in which patients are required to flex their thumb and enclose their thumb with a closed fist. While holding this specific hand posture, ulnar deviation of the wrist is either actively carried out by patients or passively by the clinician. Pain experienced at the radial side of the wrist near the radial styloid process is a positive indicator of DQV [3]. Other tests have also been proposed, such as Brunelli's test and the Wrist Hyperflexion and Abduction of the Thumb (WHAT) test [1,14]. For mild and acute cases, conservative treatments include orthotic intervention, rest, taking anti-inflammatory medication, applying heat and cold, massage and exercises [2,7,10]. A study revealed that the symptoms of mild DQV in 15 out of 17 patients are completely alleviated through a combination of orthotic intervention and oral intake of non-steroidal anti-inflammatory drugs [15].
For patients who are experiencing moderate wrist pain, corticosteroid injections may be advised. A retrospective study by Hajder, et al. [5] found that the injections of triamcinolone with an ultrasound-guided technique is safe and effective for 91% of the patients. Surgery may also be prescribed for those who cannot find relief with conservative treatments. Ta, et al. [16] found that 91% of the patients in their study experienced no complications after surgery. Previous studies have mainly focused on treatment.
For example, Ashraf, et al. [17] conducted a systematic review and meta-analysis to determine the effectiveness of steroid injection as a treatment in comparison to orthotic intervention in adults.
Cavaleri, et al. [18] included 6 eligible studies for a systematic review and meta-analysis, with the aim to examine the effectiveness of different therapeutic approaches and compare the differences in therapies, for example, orthosis treatment versus corticosteroid injections. They concluded that combined therapies of orthosis use and corticosteroid injection are more effective than any of the standalone treatments. Huisstede, et al. [19] conducted an evidencebased systematic review on the effectiveness of conservative treatment, surgical and post-surgical interventions for three hand disorders, including DQV. Besides, Stahl, et al. [20] conducted a meta-analysis on investigating the relationship between DQV and work-related manual tasks, and further examined the causal relationship between occupational risk factors and DQV. Although systematic reviews related to DQV are available, the majority have focused on a specific area of DQV. Furthermore, related systematic reviews are still minimal. Instead, research related to DQV covers broad areas, such as anatomy, diagnostic tests and treatments. This paper therefore aims to provide a comprehensive and systematic review on DQV with the following objectives: a.
To classify the articles related to DQV by year of

Methodology
A literature search was conducted by using the advanced search on the Web of Science database that involved two sets of keywords.
The first set of keywords is a list of derivations of 'DQV', and the second set of keywords is a list of other names that refer to 'DQV' and often used by the general public; see Table 1. The review period is from 1970 to Feb 2019. The following are the exclusion criteria:  The shortlisted articles were subjected to a citation network analysis (CNA) which offers an objective analysis by visualizing the interconnectivity of researchers, methodologies or articles based on their citation records [21,22]. The analysis can identify and then sort studies into different clusters or subgroups of studies that belong to the same or similar research areas which tend to review and cite each other. Furthermore, some other studies may be identified as dissimilar and isolated [22]. The CNA presents a list of the literature in the form of a network with nodes that represents a single study and links that represent the citation connections between the studies. In a directional CNA, arrowheads appear at the links, which represents the 'cite' and 'cited' relationships between studies and depicts the flow of knowledge [21,23]. Histcite, which can produce a citation index for studies retrieved from the ISI Web of Science [24], was used to export the study information and the corresponding citation data into a Pajek file, which was then imported into Gephi software to plot the graphs and visualize the networks [25].

Descriptive Statistics
In this section, the classification of the shortlisted articles is discussed in detail. Articles with an experimental design were further categorized based on the different methodologies. An overview of the research trend in DQV and study distribution was obtained from the descriptive statistics.

Year of Publication
The plotted distribution of articles related to DQV is shown in  The articles were also classified and then plotted by the country of origin of the authors, based on the provided address of the article. Thus, this distribution could point to where the studies described in the articles were actually carried out. Figure 3 shows the top 10 countries.

Methodology in Experimental Studies
According to Song, et al. [26], experimental studies can be subdivided into uncontrolled trials and controlled trials. The former are trials without a control group, while the latter include a control group for comparison purposes. They also stated that controlled trials can be further subdivided into non-randomized trials, trials without randomized allocation of subjects into intervention and control groups, and randomized controlled trials (RCTs) with subjects randomly allocated. In this study, the articles with an experimental study design are further categorized into uncontrolled trials, non-randomized controlled trials and RCTs, as shown in Figure 6. There are 21 articles (42.86%) with uncontrolled trials and 28 articles (57.14%) with controlled trials. In the latter,

Clustering of Articles
The Markov Cluster Algorithm (MCL), a clustering algorithm developed by Van Dongen [27], is well known for its effectiveness in graph clustering, reliability and robustness and therefore adopted here [28]. The MCL involves two steps to carry out random walks on a graph that show gathering of flow, which are 'expansion' and 'inflation'. The algorithm assumes that a random walk from node to node will tend to remain within a connected and more linked cluster, with a low probability of crossing the boundaries of another cluster, in which the resulting clustering is based on the existing network structure [29]. In this study, the linkages between nodes are the citation relationships with each node representing an article, which comprise the citation network structure. As the literature was objectively clustered by using the MCL, the modularity value Q which measures the strength of a citation network structure [25], was taken into consideration. The following shows the equation for Q, The citation network of studies related to DQV is developed as shown in Figure 7. Q is 0.415, which fell into the mentioned normal range. The nodes are illustrated in different sizes based on their degree. The degree of a node denotes the number of nodes that is connected to this particular node, which is the number of inward and outward connections to and from a node in a directed graph [25].
The clustering of the 197 articles in the sample by using the MCL was processed in Gephi, which resulted in 67 clusters. Of those, 56 clusters were defined as scattered groups with less than 5 articles  Figure 7 shows the citation network. Table 2 shows the cluster theme based on the cluster number. Finally, Figure 8 shows the number of articles in each cluster.

Discussion
As Some studies are in the form of case reports, which may discuss the experiences of patients with DQV, or some rare, but special and remarkable cases that cover different aspects related to DQV, for instance, the suffering experience with DQV of a female nurse [35], patients with lymphedema who suffer from DQV [36], and rare complications after corticosteroid injection [37]. These case reports show that DQV is not a simple musculoskeletal hand disorder with injection and orthotic treatment [38], corticosteroid injection and orthotic treatment versus orthotic treatment alone [39], and four-point versus two-point steroid injection [40].

Limitations
There are some limitations in this systematic study. First, there is 'selection bias'. Even though the first screening process is objectively carried out by using Histcite, the second screening process is partially subjective. Secondly, although the size of the node that represents the degree of connectivity of an article with cited works is shown in the citation network, the MCL algorithm may not include the weight and degree of connectivity of the article during the creation of the citation network. Therefore, future works would want to consider these two factors during algorithm calculation. Furthermore, the younger age group with DQV could be a research target in future studies.