Journal List > Arch Hand Microsurg > v.23(1) > 1106625

Park, Jung, Yang, Shin, and Kim: A Prospective Study of Bowstringing after A1 Pulley Release of Trigger Thumb: Percutaneous versus Open Technique



In the treatment of trigger thumb, inadequate or excessive release of the flexor pulley can lead to secondary complications such as bowstringing. However, few studies detailed bowstringing after surgical release of the A1 pulley for trigger thumb and its influence on hand function.The purpose of this study was to determine the extent to which the release of the A1 pulley causes bowstringing in the treatment of trigger thumb, and how the percutaneous technique is beneficial to bowstringing and clinical function over open technique.


The author prospectively reviewed 31 patients with resistant trigger thumb who were randomized to undergo either percutaneous release (17 patients) or open release (14 patients) of the A1 pulley. We quantified bowstringing of the thumb using ultrasonography at 12 and 24 weeks after surgery. Clinical outcomes were analyzed to correlate with the ultrasonographic measurements.


Each cohort showed a significant improvement in all clinical outcomes (p<0.05), with no difference between the groups at each follow-up (p>0.05). The bowstringing was greater increased at 12 weeks after surgery in both groups compared to before surgery (5.71±1.04 mm vs. 5.20±0.79 mm, p=0.039). However, the difference of those values was not significant at 24 weeks' follow-up (5.02±0.71 mm vs. 4.86±0.33 mm, p=0.671) There was no significant correlation between the bowstringing and any clinical outcome measures (p>0.271).


Open A1 pulley release caused greater bowstringing than percutaneous technique at initial after surgery. However, bowstringing did not affect clinical hand function in patients treated with either percutaneous or open technique.

Figures and Tables

Fig. 1

A Consort flow diagram for enrollment and analysis.

Fig. 2

A photograph of percutaneous release using the HAKI knife (BK Meditech Inc., Seoul, Korea) under ultrasound.

Fig. 3

The images of position of thumb with power flexion force on the experimenter's resistance.

Fig. 4

A measurement of flexor tendon bowstring using a B-mode ultrasound with a hockey stick transducer.

Fig. 5

A graph comparing the flexor tendon bowstring between two groups.

Table 1

Demographic and baseline characteristics of the population


Values are presented as mean±standard deviation (range) or number (%).

Table 2

Clinical outcomes after percutaneous and open A1 pulley release


Values are presented as mean±standard deviation (range).

VAS: visual analogue scale, DASH: disabilities of arm, shoulder, and hand.

Table 3

Palmar displacement of the flexor pollicis longus during power thumb flexion position of the metacarpophalangeal joint after A1 pulley release


Values are presented as mean±standard deviation.


CONFLICTS OF INTEREST The authors have nothing to disclose.


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