Chronic low back pain (CLBP) is very common in the developed countries and the majority of cases, 95 percent, are nonspecific in nature, despite the obvious pain.
Pain provocation tests can be reliable in determining the cause of some types of back pain. The authors of this study wanted to determine the reliability and discriminative ability of referred pain provocation in patients with non-specific lower back pain.
The procedure measured the pressure pain threshold (PPT) for the referred pain provocation test and researchers compared the results of standard pressure procedures with their new cross friction algometry procedure. An algometer measures pain that is caused by pressure.
The standard procedure involves asking the patient to point, with one finger, where the most intense pain is. At this point, the examiner palpates the area with one finger to find where it is most tender. When this pain is confirmed, with the question “is this the pain you are complaining of?”, this is considered local pain. However, if applying pressure at the spot produces pain in another area, this is called referred pain.
The new procedure, according to the authors, seemed to be more valid and reliable than the standard procedure. The steps were to ask the patient to point with one finger where the most intense pain is. This area is then pressed by the investigator by one finger or an elbow until the maximum tenderness is located. Deep cross-friction is then applied with the elbow in the area of the tenderness, not just the trigger point that was just located. If this produces pain in a distant area, again, this is referred pain. The deep cross-friction is done until the RP threshold is reached.
Forty-two patients with nonspecific lower back pain participated in the study. Assessments of the pain were done with the McGill Questionnaire (MPQ), which included a pain chart and a visual analog scale (VAS), and the standard Oswestry Disability Questionnaire (ODQ) for lower back pain. Using the pain chart, the patients identified their painful zones: region 1 – central or on both sides of the lower back in the lumbosacral region, region 2 – LBP that radiates into the gluteal region or thigh, region 3 – LPB with radiation to the leg but not beyond the ankle.
Following completion of the tests, among the patients who were considered to have “moderate” LBP, 52 percent had no RP and 48 percent did have RP in the leg, as they had shown in their pain drawings. Using the MPQ, the researchers were not able to determine which patients had additional RP and, although the VAS and ODI did differ, the researchers weren’t able to find clinical importance to the finding.
The authors wrote that their study found that the new technique, cross-friction algometry with the aid of a Fischer algometer, could be a viable and reliable method to find referred pain in patients with nonspecific lower back pain, as well as pain in one leg.