Clinical assessment of absence of the palmaris longus and its association with other anatomical anomalies-- a Chinese population study.

INTRODUCTION Ethnic variations in the prevalence of absence of the palmaris longus (PL) are well known. Many techniques for clinically determining the presence of the PL have been described. Studies have also attempted to correlate its absence with other anatomical anomalies. However, most studies have been done in Caucasian populations. MATERIALS AND METHODS The presence of the PL was clinically determined in 329 normal Chinese men and women using the standard technique. In subjects with an absent PL, 4 other tests were performed to confirm absence and an Allen's test was done to assess the palmar arches. All subjects were examined for the presence of the flexor digitorum superficialis (FDS) to the little finger. RESULTS The overall prevalence of absence of the PL was 4.6%. All techniques were equally effective in determining the absence of the PL. There was no significant difference in its absence with regard to the body side or sex. Absolute deficiency of FDS to the little finger was seen in 6.4%. No correlation could be detected between the absence of the PL and FDS of the little finger. CONCLUSIONS The prevalence of absence of the PL and absence of FDS to the little finger in a Chinese population is much lower compared to previous reports in the literature. There is no association between absence of the PL and absence of the FDS to the little finger. Although all techniques of examining for the absence of the PL are equally effective, the method suggested by Mishra seems the best as it was easily understood by subjects and can be used even when thumb abduction is not possible.