Miyamoto Hideaki, Miura Toshiki, Isayama Hiroyuki, Masuzaki Ryota, Koike Kazuhiko, Ohe Takashi
Department of Orthopaedic Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
J Hand Surg Am. 2011 Sep;36(9):1486-91. doi: 10.1016/j.jhsa.2011.05.038. Epub 2011 Jul 29.
The cause of snapping in trigger finger is not clearly understood. The purpose of this study was to investigate the influence of stiffness of the first annular pulley on snapping in trigger finger patients with sonoelastography, a new technique for quantitative assessment of the stiffness of soft tissues.
We first studied 20 healthy volunteers (all women, aged 24-78 y) to define the change of stiffness with aging and with specific fingers. We then studied 10 digits of 9 patients (all women, aged 60-78 y) with trigger finger that involved middle or ring fingers. Thickness and stiffness were evaluated by sonoelastography. Stiffness was estimated by strain ratio of subcutaneous fat to the pulley (F/P strain ratio). The patients were treated with corticosteroid injection, and the measurement was repeated 3 weeks later.
In the healthy volunteers, both thickness and F/P strain ratio showed a positive correlation with age. There was no difference between the middle and ring fingers. In trigger finger patients, the pulley thicknesses of the affected finger and the adjacent normal finger before corticosteroid injection were 0.99 ± 0.19 mm and 0.60 ± 0.14 mm (mean ± SD), respectively. The F/P strain ratios of the affected finger and the adjacent normal finger before the injection were 4.2 ± 1.3 and 2.4 ± 0.63, respectively. Three weeks after the injection, snapping disappeared in all patients, the pulley thickness decreased to 0.61 ± 0.15 mm, and the F/P strain ratio decreased to 2.5 ± 0.68. The cross-sectional area for flexor tendons within the pulley did not change after the injection.
Increased stiffness and thickening of the A1 pulley are considered to be causes for snapping in trigger finger, and corticosteroid injection can alleviate snapping by changing these 2 features.
扳机指弹响的原因尚不清楚。本研究旨在利用超声弹性成像技术（一种定量评估软组织硬度的新技术），研究第一环状滑车硬度对扳机指患者弹响的影响。
我们首先研究了20名健康志愿者（均为女性，年龄24 - 78岁），以确定硬度随年龄和特定手指的变化情况。然后我们研究了9例扳机指患者（均为女性，年龄60 - 78岁）的10个手指，这些患者的扳机指累及中指或环指。通过超声弹性成像评估厚度和硬度。通过皮下脂肪与滑车的应变比（F/P应变比）估计硬度。患者接受皮质类固醇注射治疗，并在3周后重复测量。
在健康志愿者中，厚度和F/P应变比均与年龄呈正相关。中指和环指之间无差异。在扳机指患者中，皮质类固醇注射前患指和相邻正常手指的滑车厚度分别为0.99±0.19mm和0.60±0.14mm（平均值±标准差）。注射前患指和相邻正常手指的F/P应变比分别为4.2±1.3和2.4±0.63。注射3周后，所有患者的弹响消失，滑车厚度降至0.61±0.15mm，F/P应变比降至2.5±0.68。注射后滑车内屈肌腱的横截面积未改变。
A1滑车硬度增加和增厚被认为是扳机指弹响的原因，皮质类固醇注射可通过改变这两个特征来缓解弹响。
