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Diagnosis of Trigger Points Through Palpation

For years, doctors and physical therapists have relied on palpation to identify trigger points (TrPs) in muscles. TrPs are areas of hyperirritable tissue. When pressed, they cause painful patterns. Each muscle has its own unique TrP pattern.

But recent research has brought the assumption that palpation is a reliable way to diagnose this problem. Part of the problem is that the testing isn't reproducible. That means the results aren't the same when the patient is tested more than once or if two different examiners conduct the same test.

In this study, researchers from the Institute of Sports Science and Clinical Biomechanics in Denmark review all the studies done on the reproducibility of manual palpation for trigger points. They came across quite a few problems.

First, not everyone uses the same terms to describe TrPs or their findings. Second, different criteria are used to identify TrPs. Sometimes the presence of local tenderness is a positive finding. Other studies used pain referral patterns as the defining test for a trigger point. And of all the studies reviewed, no one looked at the same muscles. This makes comparing the results of one study to another invalid.

Most of the studies were judged to be of poor quality and design. The way patients were selected and studied was not random or objective. Many studies only used two examiners to determine reproducibility. The authors say this simply isn't enough to reduce chance results.

The amount of pressure applied to test the muscles was also different from study to study. And in the clinic, the diagnosis usually requires a global assessment. This means touch, observation, and patient feedback are used to diagnosis trigger points. Palpation is not the only tool used to identify trigger points. None of the studies reviewed included any of these other exam techniques.

The authors did find that there was some evidence that reproducibility exists for three muscles in particular. These included the trapezius, gluteus medius, and quadratus lumborum. But the evidence was weak and further research is needed to study this area of patient care.

References: Corrie Myburgh, PhD, et al. A Systematic, Critical Review of Manual Palpation for Identifying Myofascial Trigger Points: Evidence and Clinical Significance. In Archives of Physical Medicine and Rehabilitation. June 2008. Vol. 89. No. 6. Pp. 1169-1176.

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