Department of Biomedical Engineering, Florida International University, 10555 W Flagler St, EC 2602, Miami, FL 33174, USA.
J Neuroeng Rehabil. 2013 Aug 15;10:97. doi: 10.1186/1743-0003-10-97.
Following incomplete spinal cord injury (iSCI), descending drive is impaired, possibly leading to a decrease in the complexity of gait. To test the hypothesis that iSCI impairs gait coordination and decreases locomotor complexity, we collected 3D joint angle kinematics and muscle parameters of rats with a sham or an incomplete spinal cord injury.
12 adult, female, Long-Evans rats, 6 sham and 6 mild-moderate T8 iSCI, were tested 4 weeks following injury. The Basso Beattie Bresnahan locomotor score was used to verify injury severity. Animals had reflective markers placed on the bony prominences of their limb joints and were filmed in 3D while walking on a treadmill. Joint angles and segment motion were analyzed quantitatively, and complexity of joint angle trajectory and overall gait were calculated using permutation entropy and principal component analysis, respectively. Following treadmill testing, the animals were euthanized and hindlimb muscles removed. Excised muscles were tested for mass, density, fiber length, pennation angle, and relaxed sarcomere length.
Muscle parameters were similar between groups with no evidence of muscle atrophy. The animals showed overextension of the ankle, which was compensated for by a decreased range of motion at the knee. Left-right coordination was altered, leading to left and right knee movements that are entirely out of phase, with one joint moving while the other is stationary. Movement patterns remained symmetric. Permutation entropy measures indicated changes in complexity on a joint specific basis, with the largest changes at the ankle. No significant difference was seen using principal component analysis. Rats were able to achieve stable weight bearing locomotion at reasonable speeds on the treadmill despite these deficiencies.
Decrease in supraspinal control following iSCI causes a loss of complexity of ankle kinematics. This loss can be entirely due to loss of supraspinal control in the absence of muscle atrophy and may be quantified using permutation entropy. Joint-specific differences in kinematic complexity may be attributed to different sources of motor control. This work indicates the importance of the ankle for rehabilitation interventions following spinal cord injury.
不完全性脊髓损伤（iSCI）后，下行驱动受损，可能导致步态复杂性降低。为了验证 iSCI 损伤步态协调性并降低运动复杂性的假设，我们收集了假手术或不完全性脊髓损伤大鼠的 3D 关节角度运动学和肌肉参数。
12 只成年雌性 Long-Evans 大鼠，6 只假手术和 6 只轻度中度 T8 iSCI，在损伤后 4 周进行测试。Basso-Beattie-Bresnahan 运动评分用于验证损伤严重程度。动物的肢体关节骨突上放置有反射标记，并在跑步机上行走时以 3D 拍摄。关节角度和节段运动进行定量分析，关节角度轨迹和整体步态的复杂性分别通过排列熵和主成分分析计算。在跑步机测试后，处死动物并取出后肢肌肉。取出的肌肉用于测试质量、密度、纤维长度、羽状角和松弛肌节长度。
各组肌肉参数相似，无肌肉萎缩证据。动物表现出踝关节过度伸展，通过膝关节运动范围减小来代偿。左右协调改变，导致左膝和右膝运动完全不同步，一个关节运动而另一个关节静止。运动模式仍然对称。排列熵测量指标表明，关节特异性复杂性发生变化，以踝关节变化最大。主成分分析未见明显差异。尽管存在这些缺陷，大鼠仍能以合理的速度在跑步机上实现稳定的负重运动。
iSCI 后，由于上行控制丧失，导致踝关节运动学复杂性降低。这种损失可能完全是由于在上行控制丧失的情况下没有肌肉萎缩，并且可以使用排列熵来量化。运动复杂性的关节特异性差异可能归因于不同的运动控制源。这项工作表明，踝关节对于脊髓损伤后的康复干预非常重要。
