Accuracy in the Use of Traditional Cun Measurement Techniques for Localizing Classical Acupoints in the Upper Extremity: An Experimental Study

Abstract

Background: The locations of most of the 361 classical acupuncture points are determined in clinical practice by measuring their traditionally described positions using the cun system. Some data suggest the routinely taught methods of cun measurement may lead to inaccurate acupoint localizations. Objectives: To determine the accuracy of the traditional cun measuring techniques in localizing acupoints LU 4 and TE 8 compared with tape measure determination of their optimal locations, and to assess if the ability to accurately localize these points correlates with the length of acupuncture experience. Design, Setting, and Participants: Nonrandomized, experimental study conducted with 20 physician-acupuncturists on 2 adult volunteers at a medical acupuncture conference in Fall 2009. Eleven acupuncturists independently marked the location of LU 4, and 9 acupuncturists marked the location of TE 8 by traditional cun measuring techniques on the 2 volunteers, utilizing a novel point-marking method that blinded each acupuncturist from the others' point location findings. The optimal locations for the 2 acupoints were determined by direct measurement using a tape measure. Main Outcome Measures: Distances in millimeters of the clinicians' acupuncture point localizations from the optimal point positions. Results: For LU 4, the mean inaccuracy in locating this point using traditional measurement methods was 22.3 mm (range, 5-44 mm; SD = 10.9 mm). For TE 8, the mean inaccuracy was 8.4 mm (range, 1-21 mm; SD = 5.4 mm). Years of acupuncture experience (≤10 vs >10) did not affect the accuracy of clinicians' point localizations. Conclusions: Traditional cun methods routinely used to locate acupuncture points can produce enough inaccuracy in point localization that incorrect nearby acupoints could be needled inadvertently, irrespective of the amount of clinical experience of the acupuncturist. False-negative acupuncture intervention results (i.e., no beneficial clinical effect) in clinical trials could result.