An investigation into the effect of examiner-training on the inter-examiner reliability of the palpation of myofascial trigger points
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Background: Myofascial pain is a disorder, characterized by the presence of trigger points (MTrP). It is recognised by unique features which include a tender point in a taut band of muscle, a local twitch response (LTR), a characteristic referred pain pattern, and the reproduction of the patient’s usual pain upon examination. A debate exists as to the precise diagnostic criteria used in identifying trigger points. This has hampered the standardized assessment and treatment of Myofascial Pain Syndrome and has led to contradictory findings being reported by various authors due to the lack of a reliable diagnostic tool. Objectives: The first objective was to determine the inter-examiner reliability of palpation of MTrPs in the trapezius and gluteus medius muscles. The second objective was to determine whether training and standardization in palpation techniques would improve inter-examiner reliability of palpation of MTrPs. Methods: This study was designed as a quantitative pre and post intervention interexaminer reliability study. Three examiners (one qualified Chiropractor, one senior chiropractic intern from the CDC and the researcher) were used to examine sixty patients (thirty symptomatic and thirty asymptomatic) for MTrPs. This study was conducted in two phases. During the myofascial examination of patients examiners were required to determine whether a MTrP was present or absent, differentiate whether the MTrP was active or latent and determine the presence or absence of the five characteristics of MTrP (tender point in a taut band of muscle, a local twitch response (LTR), a pain characteristic referred pain pattern, the reproduction of the patient’s usual pain and a jump sign) however, in phase one the researchers were blinded to the characteristics being investigated. Subsequent to phase one, examiners had to attend two, one hour discussion sessions to reduce individual variation in the application of palpation techniques. Results: Inter-examiner reliability was assessed using Fleiss Kappa statistic, percentage agreement and confidence intervals. The results show that three examiners are able to attain acceptable agreement in the palpation of MTrPs, since the features (described above) were shown to improve considerably in phase two after the training session in which standardization of techniques was emphasized. Conclusion: This study provides preliminary evidence that MTrP palpation is reliable and therefore, useful diagnostic tool in the identification of MTrPs and the diagnosis of Myofascial Pain Syndrome.