The appropriate depth of trigger point released by dry needling or injection at the Piriformis muscle for myofascial pain syndrome patients

Abstract

This retrospective analytical study aimed to determine the appropriate depth of trigger point released by dry needling or injection at Piriformis muscle for myofascial pain syndrome patients, and also compare the mean of Piriformis muscle depths between factors including gender, age, body sides, and body mass index (BMI). The sample consisted of patients admitted to Phetchabun Hospital and had medical treatment for the CT scan of the abdomen between 1 October 2020 and 30 September 2021. The samples were simple random sampling by random numbers generated from a total of 490 subjects. The research tools were a medical record form and a depth measurement tool in the PACS system program. Data were collected by measuring the depth of bilateral Piriformis muscles from an image of an abdominal CT scan by the ruler measurement tool in the digital medical imaging system (PACS). Data were analyzed with statistics consisting of descriptive statistics that were percentage, mean, and standard deviation, and also compared the differences in the mean of Piriformis muscle depth between differences in gender, age, body sides, and body mass index (BMI) with inferential statistics including paired t-test, independent t-test, one-way ANOVA and linear prediction equation analysis by multiple linear regression analysis.

The results were as follows:
1. The appropriate depth of trigger point released by dry needling or injection at Piriformis muscle, both age and body mass index affected the depth of trigger point released by dry needling or injection, however, gender was not affected.
2. The appropriate depth was represented by the Piriformis muscle depths which were calculated according to multiple linear regression equations (in millimeters) as follows:
2.1 Depth of right Piriformis muscle = 8.16 + (-0.10 x Age) + (2.01 x BMI)
2.2 Depth of left Piriformis muscle = 9.20 + (-0.11 x Age) + (1.99 x BMI)

In conclusion, the appropriate depth of trigger point released by dry needling or injection at the Piriformis muscle differed in age and BMI but not gender. These results can be used to determine the depth of trigger point released by dry needling or injection at the piriformis muscle in myofascial pain syndrome patients for efficiency and patient safety.