Flexor digitorum superficialis (FDS) muscle provides dynamic stabilization and medial elbow support for ulnar collateral ligament (UCL). The FDS contraction significantly affects the medial joint distance (MJD) through grip contraction. However, it remains unclear whether FDS activity alone contributes to medial elbow stability, or together with the activation of the flexor digitorum profundus during grip contraction, and which finger’s FDS is the main contributor to elbow stability. We investigated the resistive effects of isolated FDS contraction in individual fingers against valgus stress in the elbow joint using stress ultrasonography (US). We investigated 17 healthy males (mean age, 27 ± 5 years). Valgus stress US was performed using the Telos device, with the elbow at 30° flexion. MJD was measured for each arm during 3 separate conditions: at rest (unloaded), under valgus load (50 N) (loaded), and under valgus load with FDS contracted in individual fingers (loaded-contracted). MJD was significantly longer when loaded (5.4 ± 0.4 mm) than unloaded (4.1 ± 0.2 mm, P = 0.007) or loaded-contracted (4.6 ± 0.3 mm, P = 0.003) for each finger. When loaded-contracted, MJD differed statistically between the index and ring fingers (P = 0.03) and between the middle and ring fingers (P = 0.04). However, the difference between the index and middle fingers was not statistically significant (P = 0.08). Individual FDS contraction, particularly of the index and middle fingers, contributes most to stabilization against valgus stress. Thus, injury care programs should incorporate FDS exercises of these fingers.

中文翻译：

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食指和中指的浅指屈肌可增强外翻稳定性

指浅屈肌（FDS）肌肉为尺侧副韧带（UCL）提供动态稳定和肘部内侧支撑。FDS收缩通过握力收缩显着影响内侧关节距离（MJD）。但是，尚不清楚FDS的活动是否单独有助于肘部内侧的稳定性，还是与握持收缩期间指前屈屈的激活有关，以及哪个手指的FDS是肘部稳定性的主要贡献者。我们使用应力超声检查法（US）调查了单个手指的孤立FDS收缩对肘关节外翻应力的抵抗作用。我们调查了17名健康男性（平均年龄27±5岁）。使用Telos装置进行外翻应力US，肘部屈曲30°。在3个不同的条件下，对每个手臂的MJD进行了测量：在静止状态（未加载），外翻负荷（50 N）（已加载）和外翻负荷下，FDS在单个手指中收缩（加载收缩）。每个手指在加载时（5.4±0.4 mm）的MJD明显比未加载时（4.1±0.2 mm，P = 0.007）或加载收缩（4.6±0.3 mm，P = 0.003）长。加载合同后，MJD在食指和无名指之间（P = 0.03）以及中指和无名指之间（P = 0.04）在统计上有所不同。但是，食指和中指之间的差异没有统计学意义（P = 0.08）。单独的FDS收缩，尤其是食指和中指的收缩，最有助于抵抗外翻应力。因此，伤害护理计划应结合这些手指的FDS锻炼。并且在外翻负荷下，FDS收缩在各个手指上（负荷收缩）。每个手指在加载时（5.4±0.4 mm）的MJD明显比未加载时（4.1±0.2 mm，P = 0.007）或加载收缩（4.6±0.3 mm，P = 0.003）长。加载合同后，MJD在食指和无名指之间（P = 0.03）以及中指和无名指之间（P = 0.04）在统计上有所不同。但是，食指和中指之间的差异没有统计学意义（P = 0.08）。单独的FDS收缩，尤其是食指和中指的收缩，最有助于抵抗外翻应力。因此，伤害护理计划应结合这些手指的FDS锻炼。并且在外翻负荷下，FDS收缩在各个手指上（负荷收缩）。每个手指在加载时（5.4±0.4 mm）的MJD明显比未加载时（4.1±0.2 mm，P = 0.007）或加载收缩（4.6±0.3 mm，P = 0.003）长。加载合同后，MJD在食指和无名指之间（P = 0.03）以及中指和无名指之间（P = 0.04）在统计上有所不同。但是，食指和中指之间的差异没有统计学意义（P = 0.08）。单独的FDS收缩，尤其是食指和中指的收缩，最有助于抵抗外翻应力。因此，伤害护理计划应结合这些手指的FDS锻炼。007）或每个手指的负载收缩（4.6±0.3 mm，P = 0.003）。加载合同后，MJD在食指和无名指之间（P = 0.03）以及中指和无名指之间（P = 0.04）在统计上有所不同。但是，食指和中指之间的差异没有统计学意义（P = 0.08）。单独的FDS收缩，尤其是食指和中指的收缩，最有助于抵抗外翻应力。因此，伤害护理计划应结合这些手指的FDS锻炼。007）或每个手指的负载收缩（4.6±0.3 mm，P = 0.003）。加载合同后，MJD在食指和无名指之间（P = 0.03）以及中指和无名指之间（P = 0.04）在统计上有所不同。但是，食指和中指之间的差异没有统计学意义（P = 0.08）。单独的FDS收缩，尤其是食指和中指的收缩，最有助于抵抗外翻应力。因此，伤害护理计划应结合这些手指的FDS锻炼。单独的FDS收缩，尤其是食指和中指的收缩，最有助于抵抗外翻应力。因此，伤害护理计划应结合这些手指的FDS锻炼。单独的FDS收缩，尤其是食指和中指的收缩，最有助于抵抗外翻应力。因此，伤害护理计划应结合这些手指的FDS锻炼。