Arch Hand Microsurg 2018; 23(1): 20-27  
A Prospective Study of Bowstringing after A1 Pulley Release of Trigger Thumb: Percutaneous versus Open Technique
Kwang-Hee Park1, Jae-Uk Jung1, Seok-Won Yang1, Won-Jung Shin2, Jong-Pil Kim1,2
1Department of Orthopaedic Surgery, Dankook University College of Medicine, Cheonan, Korea
2Department of Kinesiology and Medical Science, Graduate School, Dankook University, Cheonan, Korea
Correspondence to: Jong-Pil Kim
Department of Orthopaedic Surgery, Dankook University College of Medicine, 119 Dandae-ro, Dongnam-gu, Cheonan 31116, Korea
TEL: +82-41-550-6579, FAX: +82-41-556-3238, E-mail:
Received: December 30, 2017; Revised: January 26, 2018; Accepted: February 2, 2018; Published online: March 1, 2018.
© Korean Society for Surgery of the Hand, Korean Society for Microsurgery, and Korean Society for Surgery of the Peripheral Nerve. All rights reserved.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Purpose: 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.
Methods: 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.
Results: 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).
Conclusion: 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.
Keywords: Trigger thumb, Bowstringing, Ultrasonography, A1 pulley, Percutaneous release, Open release

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