Finger flexor rigidity in the healthy population

The involvement of the hand flexors in trigger finger is not clear. This study aimed to examine the rigidity of the flexor tendon in the first pulley territory in the hand by using ultrasound in a healthy population, as well as to create a reference scale of rigidity for the flexor tendons to compare those values in trigger fingers. We tested 35 healthy volunteers using a linear ultrasound transducer and the color Doppler method. Rigidity levels below the first pulley were examined and compared between the different fingers of the hand and the relationship between rigidity and sex and the three different age groups was evaluated. In the healthy population, the rigidity of the flexor tendons of the hand in the territory of the first pulley varied between 233.1 and 962.8 kPa, with an average of 486.42 kPa and standard deviation of 114.85. We showed that the flexors in the dominant hand were more rigid, there was a difference between the rigidity of the flexor tendons of the thumb and the other fingers of the same hand, and the ring finger of the dominant hand had stiffer flexor tendons than the fingers of the other hand in the male population. We created a value scale for the rigidity of the flexor tendons of the fingers. This base scale can be compared between different pathologies, including trigger finger. The study and all experimental protocols were approved by the local ethical committee.