Current Status and Risk Factors of Kinesiophobia in Patients with Temporomandibular Disorders in Tianjin,China:a Cross-Sectional Study

Qi Zhang *

1Tianjin university of traditional Chinese medicine,Tianjin,China.

Abstract

Keywords: Kinesiophobia, Risk factors, Cross-sectional study, Temporomandibular disorders

Background

Temporomandibular disorders (TMD) is a collective term for diseases involving the temporomandibular joint and soft tissues, leading to craniofacial pain, headache, and mood disorders [1]. Chinese population are suffered from TMD approximately 14.9% to 17.9%[2,3]. The etiology of TMD is considered to be the result of a combination of multiple factors. Genetic predisposition, trauma,bruxism, peripheral neural mechanisms, central pain processing,psychosocial and other factors are commonly considered to be involved in the procedure of adverse outcomes of disease [4-6].Among these psychosocial factors that affect TMD, kinesiophobia have raised much attention in chronic musculoskeletal diseases in the past decades [7].

Kinesiphobia is a term which describes an excessive, irrational fear of physical activity that stems from susceptibility to painful injuries[8]. It often be discussed in Fear-avoidance model, individuals with a tendency to have catastrophic thoughts in response to pain are more prone to developing chronic pain after an injury as well as reinjury,leading to the outcomes of depression and disuse syndrome [9].

The previous study shows that higher kinesiophobia indicates the greater pain intensity and disability in chronic musculoskeletal diseases, such as chronic low back pain, knee pain, fibromyalgia,osteoarthritis, and chronic neck pain [10]. Physical exercises are often prescribe as the essential part of functional recovery and rehabilitation management [11]. However, the presence of kinesiophobia restricts the adequate execution of exercise, leading to more sedentary behaviors [12], which imposed a barrier on the procedure of clinical treatment [13,14]. In the previous study,kinesiophobia was described as the fear of fatigue, mental disorders,and the incoordination of movement between the factual needs and the athletic ability [15].

TMD shares a variety of similarities with chronic musculoskeletal diseases, but the affected area is limited to maxillofacial region. Pain is the main complaint,mandibular exercise therapy is the conservative treatment commonly used for TMD, which is beneficial to relieving symptoms [16]. The disease itself has the mechanism of amplification,which means that people who suffered from TMD are more susceptible to pain symptoms as well as sensation will last longer compared to the general population [17]. According to the fear avoidance model, once patients experience severe pain or fatigue, they are prone to forming poor cognition of disease and restricting the movement of mandibular[9]. When the discomfort reappears, the avoidance behavior will occur again, leading to abnormal mandibular behaviors, which have an enormous impact on patients’ daily life, emotion states, and seriously cause a burden to patients’ quality of life [18]. In a long term, this avoidance behavior leads to a vicious circle, that is, the positive feedback of cognitive impairments, resulting in abnormal mandibular motion compensation, joint mobility, adhesion, atrophy and masticatory muscle dysfunction [19].

However, to our knowledge, as an essential psychological factor,kinesiophobia is not well described in TMD, and no previous study had explored the risk factors of kinesiophobia in TMD patients.Hence,this study aims to explore the current status of kinesiophobia and analyze its risk factors in TMD patients, thus provide the evidence for medical staff to carry out health education strategies for patients who have a high level of kinesiophobia in clinical practice.

Materials and methods

Study design

This study was a cross-sectional study. The study was reported based on the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement: Guidelines for reporting observational studies [20]. The study was conducted between March 2019 - December 2019 in the waiting hall of the TMJ Clinic of Stomatological Hospital, Tianjin Medical University.

Participants

The Research Diagnostic Criteria Axis I for Temporomandibular Disorders (RDC/TMD-Axis I) was adopted in the present study [21].The inclusion criteria were: 1) Patients who met the RDC/TMD-Axis I and were diagnosed with TMD; 2) Age ≥18 years old, can fill in the questionnaire independently and truthfully; 3) The chief complaint is accompanied by pain symptom; 4) Voluntary participation research and fill in the informed consent form. The exclusion criteria were: 1)Patients who have recently suffered from acute and chronic pulpitis,acute and chronic apical periodontitis, or suffered head and facial trauma; 2) Patients with a history of rheumatism and rheumatoid diseases; 3) Patients with a history of mental illness and drug addiction; 4) Patients with a history of heart and liver dysfunction or malignant tumors.

The Ethics Committee of Stomatological Hospital of Tianjin Medical University approved the study (TMUhME2019001). All participants in the study signed a voluntary written consent form.

Variable measurement

Kinesiophobia.The tampa scale for kinesiophobia for Temporomandibular Disorders (TSK-TMD) was developed by Visscher in 2010 and introduced to China by He et al. to measure the status of kinesiophobia in TMD patients in 2016 [18, 22]. The scale has 12 items with 2 dimensions, including activity avoidance and somatic focus.The scale uses the Likert 4-level scoring method, ranging from 1(strongly disagree) to 4 (strongly agree), and the score ranges from 12 to 48 points. The higher score indicates the higher kinesiophobia. The Cronbach’s α coefficient of the Chinese version of the scale is 0.919,and the Cronbach’s α coefficients of the two dimensions are 0.895 and 0.907[22].

Anxiety and depression.Anxiety and depression are measured by the hospital anxiety and depression scale (HADS) [23]. The scale includes two subscales for anxiety and depression, with 7 questions each for anxiety and depression. Each question includes 4 options,ranging from 0 to 3 points. The scores of the anxiety and depression subscales are divided into: 0-7 for asymptomatic, 8-10 for suspicious symptoms, and 11-21 for certain symptoms. When the score≥ 8 points, the symptoms are regarded positive [24]. The Cronbach’s α coefficient of the Chinese version is 0.762 and 0.787 respectively,indicating good reliability [24].

Self-efficacy.The general self-efficacy scale (GSES) is a commonly used measurement tool to assess self-efficacy [25]. The GSES is single-dimensional scale that includes a total of 10 items. It uses the Likert 4-level scoring method, ranging from 1 (completely incorrect)to 4 (completely correct), corresponding to 1 to 4 points. The minimum score is 10 points and the highest is 40 points. The higher score indicates the higher the self-efficacy of the subject. The Cronbach’s α coefficient of the Chinese version of the scale is 0.87[26].

Coping style.The simplified coping style questionnaire (SCSQ) was compiled by Folkman and Lazarus to assess the characteristics of individual coping styles in the face of frustration and external stimuli[27]. The Chinese version consists of 20 items, consisting of two dimensions (subscales); the positive (items 1-12), and a negative coping style (item 13-20) [28]. The result is the average score of the positive coping dimension and the average score of the negative coping dimension. All items in the questionnaire use the Likert 4-level scoring method, with 0 to 3 points indicating no, occasionally,sometimes, and often, respectively. The positive response dimension score and the negative response dimension score are then calculated.The Cronbach’s α coefficient of the Chinese version is 0.90 [28].

Social support.The social support rating scale (SSRS) was compiled by Xiao to assess the status of patients’ social support [29]. The scale consists of 10 items with 3 dimensions: subjective support (4 items),objective support (3 items), and support utilization (3 items). The total score ranges from 11 to 72 points. The higher score indicates the higher social support. When the scores ＜33, it is considered as low social support, 33 - 45 as average social support, and ＞45 as high social support. The Cronbach’s α coefficient of the scale is 0.81, and the test-retest reliability is 0.92. It is widely used because of its good reliability and validity [30].

Sociodemographic variables. Information includes gender, age,educational level, marital status, income level, and place of residence.Disease variables.Including maximum mouth opening (MMO),mouth opening limitation (MOL), joint noise, joint locking, joint trauma, pain type, pain duration, and pain intensity. The pain intensity consists of the present pain intensity(PPI) and the worst pain intensity (WPI). MOL is considered as MMO ＜40mm. The numerical rating scale (NRS) is used for pain intensity [31]. This scale divides a straight line into 10 equal parts, with 0 means no pain and 10 means severe pain, and patients score themselves. This measurement is used internationally[32].

Statistical methods

SPSS software version 21.0 (IBM Corp., Armonk, NY, USA) was used to perform all statistical analyses. Continuous variables are represented by mean and standard deviation,and categorical variables are described by frequency and composition ratio. According to different sociodemographic characteristics and disease characteristics,the patients were divided into groups, and the student t-test or analysis of variance was used to explore the differences in kinesiophobia of TMD patients between different groups. Analyze the correlation between kinesiophobia and continuous variables. Pearson correlation analysis is used if the data conform to the normal distribution,and Spearman correlation analysis is used if the data does not conform to the normal distribution. A multivariate linear regression analysis was used to analyze the risk factors of the subjects'kinesiophobia. In all analysis,P＜0.05 was considered statistically significant.

Results

Characteristics of participants

A total of 330 questionnaires were distributed in this study, 23 invalid questionnaires (with incomplete data) were excluded, finally 307 were effective,the effective rate was 93.03%. The average age of these objects was (39.22 ± 11.29) years old. The patient’s PPI score was(4.25±1.61) points, and WPI score was (4.98±2.12) points. Other information of the patient is shown in table 1.

Kinesiophobia

The results showed that the total score of kinesiophobia of TMD patients was (34.37 ± 6.96) points, the score of activity avoidance was (19.92 ± 4.17) points, and the score of somatic focus was (14.35±3.50) points, which are higher than TMD patients in Korea [33].

Table 1 Comparison of the Sociodemographic Variables and Disease Variables of Kinesiophobia in TMD Patients

Risk factors for kinesiophbia

According to the t-test or analysis of variance, the total score of kinesiophobia was statistically significant in gender, educational level,joint noise, joint trauma, joint locking restricted opening, and pain duration (P＜0.05); There were no statistically significant differences in income level, marital status, residence, and type of pain(P＞0.05).Pearson correlation analysis showed that the total score of kinesiophobia was positively correlated with PPI (r = 0.171,P＜0.01),WPI(r=0.265,P＜0.01),negative coping style(r=0.199,P＜0.01), whereas negatively correlated with self-efficacy (r = -0.234,P＜ 0.01), objective support (r = -0.138,P＜ 0.01), and support utilization was negatively correlated (r = -0.201,P＜0.01). There was no statistically significant correlation between the total score of kinesiophobia and age, positive coping style and subjective support (P＞0.05). Multiple linear regression analysis showed that a total of 10 factors entered the final model, including pain duration, WPI, MOL,joint noise, joint trauma, self-efficacy, depression, negative coping style, support utilization and educational level. More details are described in table 2 and table 3.

Discussion

Kinesiophobia is an essential predictor of negative outcome of chronic musculoskeletal diseases [34,35]. In China, the studies involve of kinesiophobia mainly focus on knee pain [36], low back pain [37],whereas it is not well described in TMD patients. It is a special disease shared many characteristics of musculoskeletal diseases and an appropriate measurement is required to evaluate kinesiophobia in TMD patients. TSK-TMD is a specific tool which shows the good reliability and validity [18]. However, few studies have reported the level of kinesiphobia in patients by utilizing TSK-TMD. To our best knowledge, this is the first investigation that TSK-TMD was applied to measure kinesiophobia in Chinese population.

Table 2 Correlation between kinesiophobia and social psychological outcomes and pain intensity of TMD patients

Table 3 Risk factors of kinesiophobia in TMD patients

The result showed that the total scores of patients’ activity avoidance,somatic focus,and kinesiophobia were higher than those of the Korean local communities [33]. It is assumed that TMD has not been aroused public’s awareness in China. There are few professions specialized in the field of temporomandibular diseases, with the limited medical resources, the patients only acquire oral treatment when the disease seriously affects their daily life.

In the sociodemographic variables, patients with higher levels of education had a lower degree of kinesiophobia, which is consistent with the results of Gunay et al.’s study in patients with neck pain[38].Andrzej et al. conducted a study on coronary heart disease reached the same conclusion [39]. The reasons could be that patients with higher education levels pay more attention to disease-related knowledge.They may have the better understanding and acceptance of disease, as well as the better self-management ability, which make it easier for them to get the access to corresponding resources, and higher compliance with medical treatment.

In the disease variables, the patient's joint noise was found to be the risk factor for kinesiophobia, which is inconsistent with Park's research [33]. In Park’s study, joint noise was obtained by the dentist or TMD specialist, whereas it was obtained by complaint of clients in the present study. Patients may feel distressed or embarrassed about the noise of the joint in public areas, and then contributing the avoiding behaviors. Studies demonstrate that joint noise is commonly determined in TMD patients, it could be reduced or resolved during the process of treatment, symptoms would not degenerate in most occasions [40].

The patient's joint trauma and MOL are the predictors of kinesiophobia. Based on the previous study on the mechanism of TMD, approximately 21% of the etiology of TMD are caused by joint trauma, which consists of orthodontic treatment, car accident trauma,injury-causing life events, and the external force acting on the masticatory system [41].

When the force intensity and action time exceed the ability of masticatory system, inflammation and cystic change of temporomandibular joint may occur, which may lead to friction and blockage of temporomandibular joint during movement, resulting in blood accumulation in joint cavity as well as joint adhesion [42].Patients who had an experience of trauma may encounter psychological imbalance as well as the weakness of recognition, like memory degeneration, poor concentrations, lower sleep quality and mental disorders [41,43,44]. MOL can predict the level of kinesiophobia, which is consistent with the findings by the Korean scholar [33]. MOL is usually caused by articular disc displacement or muscle disease.

The typical symptom is that patients abruptly encounter the opening restriction, and then immediately revert to the formal state.However, the procedure of recovery is relatively slow [45]. WPI can be a factor to influence the level of kinesiophobia. There is an association between greater levels pain intensity and the higher degree of kinesiophobia. the longer pain duration indicates higher levels of kinesiophobia, which are consistent with Vaegter’s study conducted on chronic pain conditions [46].

The results showed that the incidence of depression, low self-efficacy, negative coping style, and low support utilization predict the degree of kinesiophobia among psychosocial variables. Depression is a type of mental disorders characterized by pessimism and lack of vitality [47]. The prevalence of depression in patients with chronic pain is about 30-54% [47,48]. Depression increases the threshold of pain perception in patients and increases the onset of chronic pain syndrome [49,50]. Evidence shows that the depression is associated with fear, as well as the higher incidence of depression indicates higher risk of chronic pain in TMD patients. Fear of pain may lead to a decrease in daily rehabilitation training and postoperative activities.Thus, leading to a decreases of muscle strength, which casts a barrier for capacity of aerobic exercise and the mental health, once such a vicious circle formed, the incidence of joint disability will be more severe [50,51]. Besides, under the influence of tension and other negative emotions, patients may have tense jaw muscles or clenched teeth, and long-term bad oral habits will cast a burden to TMD symptoms[52,53].

Self-efficacy is the factor can predict the level of kinesiophobia,which is consistent with Cai’s study which based on patients conducted a total knee arthroplasty [36]. Larsson’s study reached the same conclusion [5]. Patients with low self-efficacy are prone to have negative self-identification, it is difficult for them to carry out some self-treatment, like therapeutic exercise, consequently the avoidance behaviors of joint movement occur [54]. Joint adhesions and muscle contracture occur if there is insufficient movement of the mandible joint over a long period of time, leading to negative treatment outcomes [55]. The factor of support utilization can predict the level of kinesiophobia, which is consistent with the results of Cai’ study[36]. Osborne stated that the higher the level of social support perceived by patients with chronic pain, the less they are affected by the pain [56]. Patients with a greater levels of social support are more likely to acquire disease-related knowledge, which allow them to use social resources to buffer the pressure caused by chronic pain, thereby alleviating the stress response[56].

The results of this study provide evidence for clinical practice.Health workers can help patients with TMD to reduce kinesiophobia in the following aspects: reducing the pain intensity, alleviating unhealthy emotions, improving the patients' self-efficacy, coping ability, and the utilization of social support. Considering these therapeutic elements, our research group designed a protocol of cognitive behavioral therapy to reduce the level of kinesiophobia in patients with TMD, which has been published in a peer-reviewed journal [57].

Limitations

There are some limitations should be mentioned: First, the study is a cross-sectional study that causality cannot be clarified; second, the sample were from one specialized hospital only, it is not clear whether the results of the study can be generalized among all TMD patients.Third, the explanation rate of the risk factors of kinesiophobia is only 32.2%. Risk factors were only screened through literature review,which did not take the patients’ fatigue, mental flexibility, and other factors which may influence kinesiophobia into account. Finally, the study did not combine kinesiophobia with the severity of the disease due to the lack of diagnostic criteria for kinesiophobia. Thus, the diagnostic criteria of kinesiophobia for TMD patients should be explored in the further study.

Conclusion

This study shows that TMD patients have a high level of kinesiophobia and poor recognition of disease. The longer pain duration, high levels of pain intensity, MOL, joint locking, joint trauma, lower self-efficacy,depression, negative coping style, lower support utilization, and lower education level are independent risk factors for kinesiophobia.