Frequency of Myofascial Trigger Point in upper trapezius muscle and its associating factors among Physical therapist in Karachi, Pakistan: A cross-sectional survey.

Background: Myofascial Pain Syndrome (MPS) is the most familiar painful musculoskeletal condition often caused by Myofascial Trigger Point (MTrP). The study objective was to determine the frequency of MTrP in the upper trapezius muscle and investigate its associating factors among physical therapists. Methodology: A multi-center cross-sectional study was conducted over 258 male and female physical therapists between 20 to 45 years of age with at least 4 working hours/day. The participants filled a self-structured questionnaire, and bilateral upper trapezius MTrP was identified through the investigator's physical assessment. SPSS version 22.0 was used for statistical analysis. Frequencies and percentages were calculated for all categorical variables. Pearson chi-square test was used to compare the association of MTrP with age group, gender, and workplace. A p-value < 0.05 was considered significant. Results: Out of 258 samples, 70.5 % (n=182) were found to have MTrP in the upper trapezius muscle. Within our group, the overall frequency of latent MTrP, i.e. 71.4 %, was higher than active MTrP. Poor ergonomics of the workplace, lack of maintaining ideal posture, sleep deprivation, and emotional/psychological stress were the most rated associated factors. Conclusion: Our study provides preliminary evidence suggesting a high-frequency rate of MTrP in the upper trapezius muscle. This study also suggested a few associated factors which are the cause of developing MTrP. These factors may be useful for developing guidelines for the risk factors and intervention of upper trapezius pain.


Introduction
MPS has been identified as a painful musculoskeletal condition often associated with MTrP 1 . So far, MrTP is a poorly diagnosed and ineffectively treated source of muscle pain reported in health care settings with point prevalence 10 %-18 % and lifetime prevalence 30 % -50 % 2,3 . The prevalence of MTrP has been increasing in recent years. MTrP was found more frequent in the trapezius muscle 4 . MTrP is characterized as distinct and local hypersensitive points found in a taut band of a skeletal muscle. On compression, these points are painful, and they produce reproducible pain familiar to patient pain pattern, tenderness, and muscle weakness 5 .
Trigger points can be differentiated into two types on the presence of their clinical features. If the pain produces at rest, tender to palpation with a referred pain pattern similar to the patient's pain complaint, it is an active trigger point 6 . Furthermore, if the localized compression does not produce an instinctive nature pain but may restrict movement or cause muscle weakness, it is called a latent trigger point 7 .
Prior literature has proved that the frequency of various musculoskeletal disorders is high among health care professionals 9 . Physiotherapy is a part of the rehabilitation of treating patients manually in offices and clinics. The therapist often applies excessive force in a static uncomfortable position while handling the patient. Furthermore, physiotherapists also may routinely perform activities such as transferring depending on patients, assisting patients in gait, providing manual resistance, assisting with mat activities, and lifting heavy and cumbersome equipment. Other risk factors include lack of reporting their injury, treating themselves independently, extended clinical hours, and treating many patients in one shift 10 . These factors influence the progress of musculoskeletal disorder that is more often myofascial 11,12 . Musculoskeletal discomfort among physiotherapists disturbs the productivity, performance, treatment quality, and individual's health also. The physiotherapists have to be painfree, healthy, and comfortable to maintain work efficiency 13,14 .
However, physiotherapists suffering from musculoskeletal pain often change the way they work, which may adversely affect the quality of treatment 15 . However, such surveys have been performed previously to find the prevalence, management, and comparison of MTrP among those who have already neck pain and shoulder pain 3,16 . To the best of our knowledge, no study determined the frequency of MTrP in particularly upper trapezius muscle and its associating factors among physical therapists in the local community 3 . Therefore, the primary purpose of this study was to determine the frequency of MTrP in upper trapezius muscle and to investigate its associating factors among physical therapists, which may be useful in developing the guidelines for the risk factors and intervention approach of upper trapezius pain Methodology A cross-sectional study was conducted from October to December 2016 in multi-center wellknown physiotherapy out-patient departments around Karachi. The study was approved by the institute of physical medicine & Rehabilitation, Dow University of Health Sciences. A total of 258 participants were voluntarily recruited after explaining the study protocol and informed consent. In this study, the participant must be physical therapists of age between 25 to 45 years with at least 4 working hours/day. A self-designed questionnaire was directed amongst those who fulfilled the inclusion criteria. The individual physical examination was performed to identify the MTrP of bilateral upper trapezius muscle by researchers manually.
Data was entered and analyzed using SPSS version 22.0; frequencies and percentages were calculated to determine the frequency of MTrP, location, types, and common factors. Pearson chi-square test was used to see the association of MTrP with age group, gender, and workplace. A p-value < 0.05 was considered significant. A pie chart was used to show the frequency of MTrP, and a bar chart was used to show the percentages of MTrP location and its types.

Results
In the present study, 258 participants were enrolled, and out of them, 70.5 % were observed with MTrP (Graph 1), 71.4 % MTrP participant found with the type of Latent MTrP, and 38.5 % found with the Right location, whereas 46.7 % participants found with the bilateral location of MTrP (Graph 2).

MTrP location MTrP type
MTrP was found commonly in 74.02 % of male participants. 90.91 % from 41-45 years old were suffering from MTrP. 73.59 % had Hospital as a workplace. However, there was no significant association of MTrP found with gender, age group, and workplace (Table 1).   Almost all our participants with neck pain (58.2 %) presented MTrPs in the upper trapezius. Most of these trigger points were active as subjects were familiar with the location and the quality of the referred pain elicited by pressure applied during physical examinations for MTrP. In our participants, the higher rate of MTrP in the right upper trapezius than left upper trapezius shows that the dominant side is more prone to develop MTrP in a physical therapist. Although the bilateral presence of MTrP is more common in this study, that is 46.7 %.
Total 56.6 % of participants reported worsening of pain while working. One study has resulted as a physiotherapist job requires transferring dependant patients, assisting them in gait training, providing manual resistance in some patients, assisting with MET activities, and lifting heavy and cumbersome equipment that all are responsible for developing MTrP 18 . 38.5 % agreed that treating their pain with physiotherapy techniques makes their pain better. 22.0 % of samples marked 'often' for headache due to pain.
In some previous studies, it has been proposed that tension-type headache may originate, at least to some extent, from referred pain from MTrPs located in the head, neck, and shoulder muscles 19 . It is also concluded in another study that myofascial trigger point can be an important mechanism that causes cervicogenic headaches 20 . It is observed from the questionnaire that 44.5 % of samples reported 6-8 working hours. 36.8 % of samples said they take rest every two hours during working.
The current study has several features making it a strong observational survey, as it is the first of its kind and comprised qualified physiotherapists. The response rate of 100 % is also a notable feature even though it was a multi-center study. However, the study is a valuable sample of the physical therapist in Karachi. This study's results can be used for future studies to explore the broader population's prevalence ratio.

Conclusion
The study concludes that the frequency of MTrP in the upper trapezius muscle is very high among physical therapists. The results of this study also determined some of the most rated associating factors for the physical therapist's poor ergonomics of workplace, sleep deprivation, and emotional/psychological stress. These factors may be useful for developing guidelines for the risk factors and intervention of upper trapezius pain. Thus, specific strategies should be considered to reduce the probability of MTrP.

Conflicts of Interest
None.