Interrater Reliability in the Clinical Evaluation of Myofascial Trigger Points in Three Ankle Muscles

The purpose of this study was to evaluate interrater reliability in the diagnosis of myofascial trigger points (MTrPs) in the tibialis anterior, peroneus brevis, and extensor digitorum longus muscles.

A reliability research study was performed. Three physical therapists with clinical experience in myofascial pain functioned as raters and randomly and bilaterally evaluated the ankles of 40 subjects in the Madrid public health care system. The absence or presence of MTrPs, nodules in taut bands, patterns of referred pain, local twitch response (LTR), and jump-sign were evaluated.

We calculated the pairwise interrater agreement and κ-value concordance of the presence or absence of trigger points (55%-85%; κ = 0.12-0.60), palpable nodules in taut bands (63%-90%; κ = 0.24-0.60), referred pain (63%-85%; κ = 0.20-0.54), and jump sign (62%-89%; κ = 0.15-0.72) in the 3 studied muscles. The LTR could only be evaluated in the tibialis anterior (43%-70%; κ = 0.05-0.21), and evaluation was not possible for the other muscles.

Three blinded raters were able to reach acceptable pairwise interrater agreement (percentage of agreement value ≥70%) for the presence or absence of MTrPs and LTR in the tibialis anterior, as well as for nodules in taut bands, referred pain, and the jump sign for the extensor digitorum longus. The peroneus brevis showed a wide percentage of agreement value, ranging from 31% to 82%. The results of this study showed that expert raters can agree, with slight-to-moderate concordance, with regard to the clinical testing of muscle trigger points by direct palpation of the 3 muscles studied: the tibialis anterior, the extensor digitorum longus, and the peroneus brevis. Interrater reliability seems to be muscle dependent, especially with regard to the depth of the muscle.