Abstract：
OBJECTIVE: Measurement of medial gastrocnemius (MG) tendon length using ultrasonography (US) requires the muscle-tendon junction (MTJ) to be located. Previously, the MG MTJ has been tracked from different proximo-distal locations near the MTJ, which could influence estimates of tendon length change due to the different characteristics of the aponeurosis and tendon. We used US to evaluate the effect of tracking point location on MG MTJ displacement during maximal and submaximal (10, 20 and 30% of the non-injured maximal) isometric plantar flexion contractions.
METHODS: Displacement behaviour of MTJ was tracked from (1) the exact MTJ; and (2) from an insertion point of a muscle fascicle on the aponeurosis 1.3 ± 0.6 cm proximal to the MTJ, in both limbs of patients with unilateral Achilles tendon rupture (ATR) (n = 22, 4 females, 42 ± 9 years, 177 ± 9 cm, 79 ± 10 kg).
RESULTS: In the non-injured limb, displacement (1.3 ± 0.5 cm vs. 1.1 ± 0.6 cm) and strain (6.7 ± 2.8% vs. 5.8 ± 3.3%) during maximal voluntary contraction were larger when tracking a point on the aponeurosis than when tracking the MTJ (both p < 0.001). The same was true for all contraction levels, and both limbs.
CONCLUSIONS: Tracking a point on the aponeurosis consistently exaggerates estimates of tendon displacement, and the magnitude of this effect is contraction intensity-dependent. When quantifying displacement and strain of the Achilles tendon, the MTJ should be tracked directly, rather than tracking a surrogate point proximal to the MTJ. The latter method includes part of the aponeurosis, which due to its relative compliance, artificially increases estimates of MTJ displacement and strain.
METHODS: Displacement behaviour of MTJ was tracked from (1) the exact MTJ; and (2) from an insertion point of a muscle fascicle on the aponeurosis 1.3 ± 0.6 cm proximal to the MTJ, in both limbs of patients with unilateral Achilles tendon rupture (ATR) (n = 22, 4 females, 42 ± 9 years, 177 ± 9 cm, 79 ± 10 kg).
RESULTS: In the non-injured limb, displacement (1.3 ± 0.5 cm vs. 1.1 ± 0.6 cm) and strain (6.7 ± 2.8% vs. 5.8 ± 3.3%) during maximal voluntary contraction were larger when tracking a point on the aponeurosis than when tracking the MTJ (both p < 0.001). The same was true for all contraction levels, and both limbs.
CONCLUSIONS: Tracking a point on the aponeurosis consistently exaggerates estimates of tendon displacement, and the magnitude of this effect is contraction intensity-dependent. When quantifying displacement and strain of the Achilles tendon, the MTJ should be tracked directly, rather than tracking a surrogate point proximal to the MTJ. The latter method includes part of the aponeurosis, which due to its relative compliance, artificially increases estimates of MTJ displacement and strain.
摘要：
目的：使用超声（US）测量腓肠肌内侧（MG）肌腱长度需要定位肌肉-肌腱接头（MTJ）。以前,已从MTJ附近的不同近端-远端位置跟踪MGMTJ，由于肌腱膜和肌腱的不同特征，这可能会影响肌腱长度变化的估计。我们使用US评估了最大和次最大（非损伤最大的10％，20％和30％）等轴测足屈收缩期间跟踪点位置对MGMTJ位移的影响。
方法：从（1）精确的MTJ跟踪MTJ的位移行为；（2）从靠近MTJ1.3±0.6cm的腱膜上的肌束的插入点，单侧跟腱断裂（ATR）患者的四肢（n=22，4名女性，42±9岁,177±9厘米，79±10kg)。
结果：在未受伤的肢体中，位移(1.3±0.5cmvs.1.1±0.6cm）和应变（6.7±2.8％vs.5.8±3.3％）在最大自愿收缩期间，当跟踪肌腱膜上的点时比跟踪MTJ时更大（均p<0.001）。所有收缩水平都是如此，和四肢。
结论：追踪肌腱膜上的一点始终夸大了肌腱位移的估计，这种效应的大小与收缩强度有关。当量化跟腱的位移和应变时，应该直接跟踪MTJ，而不是跟踪MTJ附近的代理点。后一种方法包括部分肌腱膜，由于其相对合规性，人为增加MTJ位移和应变的估计。
方法：从（1）精确的MTJ跟踪MTJ的位移行为；（2）从靠近MTJ1.3±0.6cm的腱膜上的肌束的插入点，单侧跟腱断裂（ATR）患者的四肢（n=22，4名女性，42±9岁,177±9厘米，79±10kg)。
结果：在未受伤的肢体中，位移(1.3±0.5cmvs.1.1±0.6cm）和应变（6.7±2.8％vs.5.8±3.3％）在最大自愿收缩期间，当跟踪肌腱膜上的点时比跟踪MTJ时更大（均p<0.001）。所有收缩水平都是如此，和四肢。
结论：追踪肌腱膜上的一点始终夸大了肌腱位移的估计，这种效应的大小与收缩强度有关。当量化跟腱的位移和应变时，应该直接跟踪MTJ，而不是跟踪MTJ附近的代理点。后一种方法包括部分肌腱膜，由于其相对合规性，人为增加MTJ位移和应变的估计。
