Healthy Hoofcare, Albuquerque, NM, United States of America.
University of Edinburgh, The Royal (Dick) School of Veterinary Studies, Edinburgh, United Kingdom.
PLoS One. 2018 Jun 21;13(6):e0199447. doi: 10.1371/journal.pone.0199447. eCollection 2018.
In trotting horses, movement asymmetry is associated with ground reaction force asymmetry. In humans, limb length differences influence contralateral force production. Here we investigate whether horses, in immediate reaction to limb length changes, show movement asymmetry adaptations consistent with reported force differences. Aim of this study was to quantify pelvic and compensatory head and withers movement asymmetry as a function of limb length changes after application of orthotic lifts. In this experimental study movement asymmetry of eleven trotting horses was calculated from vertical displacement of poll, withers, sacrum and left and right tuber coxae with inertial sensors. Horses were assessed in-hand under 5 conditions (all with hind limb boots): without orthotic lifts, and with a 15mm or 30mm orthotic lift applied to the left hind or right hind. A linear mixed model investigated the influence of orthotic lift condition (P<0.05, pairwise posthoc Bonferroni correction). Pelvic movement asymmetry showed increased pelvic downward movement during stance of the shorter limb and increased pelvic upward movement during and after stance of the longer limb (P<0.001) with asymmetry changes of 3-7mm (4-10mm) for 15mm (30mm) lifts. Hip hike (tuber coxae movement asymmetry) was unaffected (P = 0.348). Head and withers movement asymmetry were affected less consistently (2 of 3 respectively 1 of 3 head or withers parameters). The small sample size of the study reduced generalizability, no direct force measurements were conducted and only immediate effects of orthotic lifts were assessed with no re-assessments days or weeks after. Conclusions about mechanical consequences (weight bearing, pushoff) are based on published movement-force associations. Pelvic movement asymmetry with an artificial change in limb length through application of an orthotic lift indicates increased weight support with the shorter limb and increased pushoff with the longer limb. This may be of relevance for the management of horses with different hoof shapes between contralateral limbs, for example some chronically lame horse.
在快步马中，运动不对称与地面反作用力不对称有关。在人类中，肢体长度差异会影响对侧力的产生。在这里，我们研究了马在立即对肢体长度变化做出反应时，是否会表现出与报道的力差异一致的运动不对称适应。本研究的目的是量化骨盆和补偿性头部和肩部运动的不对称性，作为肢体长度变化后应用矫形器提升的函数。在这项实验研究中，通过惯性传感器测量 11 匹快步马的项、肩、荐骨和左右坐骨结节的垂直位移，计算出运动的不对称性。在 5 种条件下（所有后肢均穿着靴子）：不使用矫形器提升，以及在左后肢或右后肢上使用 15mm 或 30mm 的矫形器提升。线性混合模型研究了矫形器提升条件的影响（P<0.05，两两事后 Bonferroni 校正）。骨盆运动不对称表现为较短肢体的支撑期骨盆向下运动增加，较长肢体的支撑期和支撑后期骨盆向上运动增加（P<0.001），15mm（30mm）提升的不对称变化为 3-7mm（4-10mm）。髋部提升（坐骨结节运动不对称）不受影响（P=0.348）。头部和肩部运动不对称的影响不那么一致（3 个参数中的 2 个分别为 1 个头部或肩部参数）。研究的样本量较小，降低了通用性，没有进行直接的力测量，并且仅在矫形器提升后的几天或几周内评估了即时影响，没有重新评估。关于机械后果（承重、离蹄）的结论是基于已发表的运动-力关联得出的。通过应用矫形器改变肢体长度，骨盆运动的不对称性表明较短肢体承重增加，较长肢体离蹄增加。这对于管理对侧肢体之间具有不同蹄形的马，例如一些慢性跛行的马，可能具有重要意义。
