Objective: Some authors have hypothesized that the pathogenesis of mechanical neck pain is mainly produced by musculoskeletal disorders, i.e., myofascial pain syndrome trigger points [TrPs] and cervical joint dysfunctions. The relationship between muscles and joint dysfunctions is well recognized by clinicians, but there are not many published papers analyzing this clinical situation. The aim of the present trial was to analyze the relationship between the presence of TrPs in the upper trapezius muscle and the presence of cervical dysfunctions at C3 and/or C4 vertebrae in patients suffering from mechanical neck pain. Methods: One hundred and fifty patients suffering from mechanical neck pain participated in this clinical trial. Patients were examined for TrPs by Therapist 1 and for cervical dysfunctions by Therapist 2. Both therapists were blinded to the other physical exploration. The diagnosis of the TrPs was based upon the diagnostic criteria of Travell and Simons. Pressure on the TrPs was applied with a Pressure Threshold Meter and was increased continuously approximately at a rate of 1 kg/cm(2)/seg to a maximum of 2.5 kg/cm(2) of pressure. Physical examination of cervical dysfunction was based upon the "lateral gliding test for the cervical spine" following the guideline described by Greenman. Results: Latent TrPs in the upper trapezius Muscle were shown in 56 percent of patients, whereas 28 percent subjects showed active TrPs. The remaining patients did not show TrPs, but Father tender points [TePs] were found. Ninety-seven percent of subjects showed a cervical dysfunction ipsilateral to the TrP or Tep. Further analysis showed a significant relationship between the presence of TrPs in the upper trapezius muscle and the isolate presence of a dysfunction at C3 vertebra [P = 0.03], and the presence of dual dysfunctions at C3 and C4 vertebrae [P = 0.03]. Conclusion: There is a possible relationship between the presence of TrPs in the upper trapezius muscle and the presence of cervical dysfunctions at C3 and C4 vertebrae in patients suffering from mechanical neck pain. However, it can not be established as a cause-effect relationship. Moreover, there is clinical evidence showing that joint dysfunctions can induce TrP activity, and that TrP activity can aggravate corresponding joint dysfunction.
