Fortius Clinic, London, UK.
The Biomechanics Group, Department of Mechanical Engineering, Imperial College London, UK.
Am J Sports Med. 2018 Mar;46(4):955-960. doi: 10.1177/0363546517745291. Epub 2017 Dec 18.
The plantaris tendon (PT) has been thought to contribute to symptoms in a proportion of patients with Achilles midportion tendinopathy, with symptoms improving after PT excision.
There is compression and differential movement between the PT and Achilles tendon (AT) during ankle plantarflexion and dorsiflexion.
Descriptive laboratory study.
Eighteen fresh-frozen cadaveric ankles (mean ± SD age: 35 ± 7 years, range = 27-48 years; men, n = 9) were mounted in a customized testing rig, where the tibia was fixed but the forefoot could be moved freely. A Steinmann pin was drilled through the calcaneus, enabling a valgus torque to be applied. The soleus, gastrocnemius, and plantaris muscles were loaded with 63 N with a weighted pulley system. The test area was 40 to 80 mm above the os calcis, corresponding to where the injury is observed clinically. Medially, the AT and PT were exposed, and a calibrated flexible pressure sensor was inserted between the tendons. Pressure readings were recorded with the ankle in full dorsiflexion, full plantarflexion, and plantargrade and repeated in these positions with a 5 N·m torque, simulating increased hindfoot valgus. The pressure sensor was removed and the PT and AT marked with ink at the same level, with the foot held in neutral rotation and plantargrade. Videos and photographs were taken to assess differential motion between the tendons. After testing, specimens were dissected to identify the PT insertion. One-way analysis of variance and paired t tests were performed to make comparisons.
The PT tendons with an insertion separate from the AT demonstrated greater differential motion through range (14 ± 4 mm) when compared with those directly adherent to the AT (2 ± 2 mm) ( P < .001). Mean pressure between the PT and AT rose in terminal plantarflexion for all specimens ( P < .001) and was more pronounced with hindfoot valgus ( P < .001).
The PT inserting directly into the calcaneus resulted in significantly greater differential motion as compared with the AT. Tendon compression was elevated in terminal plantarflexion, suggesting that adapting rehabilitation tendon-loading programs to avoid this position may be beneficial.
The insertion pattern of the PT may be a factor in plantaris-related midportion Achilles tendinopathy. Terminal range plantarflexion and hindfoot valgus both increased AT and PT compression, suggesting that these should be avoided in this patient population.
人们认为，在一部分患有跟腱中部腱病的患者中，跖肌腱（PT）会导致症状出现，而切除 PT 后症状会得到改善。
在踝关节跖屈和背屈过程中，PT 与跟腱（AT）之间存在压迫和差异运动。
描述性实验室研究。
18 个新鲜冷冻的踝关节标本（平均±标准差年龄：35±7 岁，范围=27-48 岁；男性，n=9）安装在定制的测试架上，胫骨固定但前脚可以自由移动。在跟骨上钻一根斯氏针，以便施加外翻扭矩。使用带加重滑轮系统的 63N 对比目鱼肌、腓肠肌和跖肌进行加载。测试区域位于跟骨上方 40 至 80mm 处，与临床上观察到的损伤部位相对应。在内部，暴露 AT 和 PT，并在肌腱之间插入校准的柔性压力传感器。在踝关节完全背屈、完全跖屈和跖屈位记录压力读数，并在这些位置施加 5N·m 的扭矩以模拟后足外翻增加，然后重复测量。移除压力传感器，并在同一水平标记 PT 和 AT，使脚保持中立旋转和跖屈位。拍摄视频和照片以评估肌腱之间的差异运动。测试后，将标本解剖以确定 PT 插入点。使用单向方差分析和配对 t 检验进行比较。
与直接附着于 AT 的肌腱（2±2mm）相比，具有与 AT 分离的插入点的 PT 肌腱在整个运动范围内具有更大的差异运动（14±4mm）（P<0.001）。所有标本的 AT 和 PT 之间的平均压力在终末跖屈时升高（P<0.001），在后足外翻时更为明显（P<0.001）。
直接插入跟骨的 PT 导致明显更大的差异运动，与 AT 相比。终末跖屈时肌腱受压升高，表明在这种患者人群中应避免适应康复肌腱加载方案的这种位置。
PT 的插入模式可能是跟腱中部腱病中与跖肌腱相关的一个因素。终末运动范围跖屈和后足外翻都增加了 AT 和 PT 的压缩，因此建议在这类患者中避免这两种情况。
