Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.
Equine Vet J. 2020 Mar;52(2):314-319. doi: 10.1111/evj.13135. Epub 2019 Jun 27.
Equine diagnostic anaesthesia can be a useful tool in challenging lameness examinations. However, anaesthetics diffuse over time leading to nonspecific desensitisation of periarticular structures. Nerves that convey sensation from the distal limb to the central nervous system pass in close proximity to the caudal stifle joint capsule. Therefore, diffusion of intra-articular (IA) anaesthetics could cause inadvertent desensitisation of the distal limb resulting in a false diagnosis of stifle lameness.
To determine if IA stifle anaesthesia can alleviate lameness originating in the distal limb.
Crossover experiment.
Nine horses were fitted with a circumferential hoof clamp to induce a moderate unilateral hindlimb lameness. Intra-articular stifle anaesthesia was performed and gait was evaluated every 10 min during the 90-min trial using an inertial sensor system. Push-off and landing components of the lameness were assessed by measuring the mean inter-stride difference between the maximum and minimum heights of the pelvis respectively. Differences were compared using a Wilcoxon signed-rank test.
Overall, horses with hoof clamp-induced foot pain had a reduction in push-off lameness after IA stifle anaesthesia. The mean change in diffmax at 90 min was -4.3 mm (P = 0.005) for the experimental group vs. -2.3 mm (P = 0.2) for the control group. Lameness decreased over time, with an average improvement of 23% at 30 min, 33% at 60 min and 38% at 90 min. There was high inter-horse variability; 3/9 horses improved by ~50% within 30 min, while 2/9 improved by ~30% and 4/9 had minimal (<10%) or no improvement in lameness. Improvement after IA stifle anaesthesia was not related to the severity of baseline lameness (P = 0.3-0.7).
Limited clinical applicability of our lameness induction model.
Intra-articular stifle anaesthesia reduces foot lameness in a third of horses by up to 50% within 30 min. Clinically, the results of IA stifle anaesthesia should be considered in the light of these findings before treatment recommendations are made, as additional diagnostics may be required to rule out pain originating in the distal limb.
马属动物诊断性麻醉在检查困难性跛行时可能是一种有用的工具。然而，麻醉剂会随着时间的推移而扩散，导致关节周围结构的非特异性脱敏。传递来自远端肢体的感觉的神经与尾膝关节囊紧密相邻。因此，关节内（IA）麻醉剂的扩散可能导致远端肢体的意外脱敏，从而导致假性膝关节跛行的诊断。
确定关节内膝关节麻醉是否可以减轻起源于远端肢体的跛行。
交叉实验。
给 9 匹马安装环形蹄夹以引起中度单侧后肢跛行。进行关节内膝关节麻醉，并在 90 分钟试验期间使用惯性传感器系统每 10 分钟评估一次步态。通过测量骨盆最大和最小高度之间的平均跨步差异来评估跛行的蹬离和着地成分。使用 Wilcoxon 符号秩检验比较差异。
总体而言，患有蹄夹引起的足部疼痛的马在进行关节内膝关节麻醉后，蹬离跛行减轻。实验组在 90 分钟时的 diffmax 平均变化为-4.3 毫米（P=0.005），而对照组为-2.3 毫米（P=0.2）。跛行随时间逐渐减轻，30 分钟时平均改善 23%，60 分钟时改善 33%，90 分钟时改善 38%。马之间的个体差异很大；9 匹马中有 3 匹马在 30 分钟内改善了约 50%，2 匹马改善了约 30%，4 匹马跛行改善程度最小（<10%）或无改善。关节内膝关节麻醉后的改善与基线跛行的严重程度无关（P=0.3-0.7）。
我们的跛行诱导模型在临床应用上存在局限性。
关节内膝关节麻醉可在 30 分钟内使多达 33%的马的足部跛行减轻 50%。在临床上，应根据这些发现考虑关节内膝关节麻醉的结果，然后再提出治疗建议，因为可能需要额外的诊断来排除起源于远端肢体的疼痛。
