the trigger finger is in the clinical practice , frequently caused by stenosing tenosynovitis at the a1 pulley characterized by pain , swelling and a triggering sensation with the limitation of finger motion .
the first treatment is conservative using anti - inflammatory drugs and steroid injection , but some resistant cases may need surgery .
post - traumatic trigger finger is a rare case of resistant trigger finger that can be suspected recording an accurate clinical history and in case of resistant trigger finger after anti - inflammatory drugs therapy and steroid injection.[26 ] .
we report a case of post - traumatic trigger finger due to a partial longitudinal tear of the flexor digitorum superficialis .
a healthy 22-year - old caucasian male referred to our department suffering from pain and limited range of motion ( rom ) of the right ring finger . the patient sustained in august 2015 a penetrating injury on the palm of the right hand during his sport activity .
he did not refer to any emergency department or general pratictioner , the wound was small and healed naturally .
one month later pain started and limitation of rom of the right ring finger gradually worsened .
because of his clinical disorders , a trigger finger was diagnosed by another orthopedic who performed a steroid injection .
the clinical examination showed a small scar on the palm , located proximally to the fourth metacarpophalangeal joint and the rom of the proximal interphalangeal ( pip ) joint of the ring finger was limited to 40 degrees of extension and complete ( 100 degrees ) in flexion , both in passive and active motion .
the feeling of numbness just under the scar , the first steroid injection that was not effective and the young age of the patient , led us to perform an ultrasound examination of the hand tendons ( figure 1 ) , which showed a suspect tear of the flexor digitorum superficialis tendon of the ring finger , proximally to the pulley a1 that appeared thickened .
the surgical exploration of the tendon was the treatment of choice , which was performed 2 months and 10 days from the injury .
the ultrasounds examination shows an irregular region ( arrow ) of the flexor digitorum superficialis tendon suggestive of a partial rupture , accompanied by the thickening of the pulley a1 ( asterisk ) .
p : proximal phalanx ; m : metacarpus ; mpj : metacarpo - phalangeal joint .
the incision was made at the pulley a1 and extended brunner - like proximally in direction of the scar .
a partial longitudinal flap - shaped tear was discovered , large approximately half of the entire tendon diameter , of the radial half of the flexor digitorum superficialis tendon that hooked at the entrance of the a1 pulley ( figure 2 ) .
the flexor digitorum profundus tendon was intact . because of the size of the flap - shaped tear , it was decided not to remove it , but it was sutured to the tendon in anatomic position with simple stitches ( nylon 4 - 0 ) and the pulley a1 release completed the procedure to avoid risk of post - operative re - triggering .
the examination during surgery showed the restoration of ring finger rom ( 0100 degrees ) and the disappearance of the trigger , then the exploration of the distal pulleys ( a2 and a3 ) was not necessary . also , a capsulotomy of the pip was not necessary because the limitation of rom was not due to a capsular contracture .
the patient was recommended to frequently move the fingers even with the bandage , to prevent the formation of adhesions .
there was no need for physiotherapy as the rom has been completely restored almost immediately .
after 3 months of follow - up , no evidence of relapse was recorded and the rom was 0100 degrees .
the picture shows the longitudinal partial flap - shaped tear of the flexor digitorum superficialis .
most of the patients affected by trigger fingers are treated with anti - inflammatory drugs or steroid injection .
the success rate of the single - dose of a steroid injection is reported to be 50% and when the conservative treatment fails , open a1 pulley release has a success rate of approximately 100% . in literature some cases of resistant trigger finger caused by rare conditions , such as phalangeal osteochondroma , tendon sheets tumor ( fibroma or giant cell tumor )   or calcifying tenosynovitis   have been reported . more frequent , but still rare in the clinical practice ,
is the trigger finger due to a partial tear of the flexor digitorum . to our knowledge , there are only few reports in literature.[210 ] previous reports advised the imaging support for the diagnosis of triggering after partial flexor tendon tear .
more recently , okano and couceiro in two different reports used mri for the diagnosis .
our recent case , together with the other few reported in literature , demonstrates that the diagnosis of trigger finger , although does not present difficulties in the majority of the cases , have to be supported by an accurate clinical history and clinical examination , because in some cases it can be the consequence of rare clinical conditions . in selected cases , mostly if post - traumatic , the ultrasound imaging or the mri can be used to perform a correct diagnosis , and subsequently a correct treatment .
the authors declares that there is no conflict of interest regarding the publication of this paper .
 abstractwe report a case of post - traumatic trigger finger due to a partial longitudinal tear of the flexor digitorum superficialis . 
 the suspect came from the clinical history and the young age of the patient . 
 it was successfully treated with tendon flap suture and pulley a1 release . 
Introduction
Case report
Discussion
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