The incidence of palmaris longus in the heterogeneous Israeli population

We evaluated the frequency of absence of the palmaris longus tendon in the heterogeneous Israeli population. Nine hundred and fifty wrists were evaluated using a modified Mishra/Schaeffer technique (thumb/little-finger opposition with resisted wrist flexion), which was validated by ultrasound scanning. The geographical and ethnic origin of volunteers was documented. When physical examination was equivocal, any vague, superficial structure was subsequently identified as the median nerve by ultrasound. Physical examination reliably identified palmaris longus only when a structure was clinically obvious (visually or by palpation). There was bilateral absence of the palmaris longus in 21% and unilateral absence in 15% of participants. Frequency of bilateral absence varied between 4.5% and 30%, depending on geographical origin (p = 0.0007). The incidence of palmaris longus tendon varied significantly by geographical, but not by ethnic origin.Level of evidence: II.