Effect of different resting time on patella-patellar tendon healing after acute injury

doi:10.3969/j.issn.2095-4344.2017.12.001

Abstract

Abstract:

BACKGROUND: Patella-patellar tendon junction (PPTJ) injuries are a common disease in athletes and vulnerable to re-injury. Post-injury training is a double-edged sword.
OBJECTIVE: To examine the effect of post-injury resting days on the quality of healing in PPTJ in view of histomorphology, expression levels of growth factor and collagen, and muscle tension.
METHODS: Forty New Zealand white rabbits were randomly divided into control, and five post-injury training groups representing different time to restart training after acute injury: the rabbits restarted training at 24 (PIT24), 48 (PIT48), 72 (PIT72), 96 (PIT96) and 120 (PIT120) hours, respectively. All post-injury training groups received acupuncture at the PPTJ and then underwent 4-week low-intensity training. Afterwards, all rabbits were killed to take specimens for hematoxylin-eosin, safranin O and immuohistochemical staining. The muscle tension and hardness were detected using Myoton-3. The thickness of fibrous cartilage zones, cell density, as well as the expression levels of vascular endothelial growth factor and collagen were measured on Metamorph software.
RESULTS AND CONCLUSION: Compared with the control group, in the PIT groups, the collagens arranged in disorder, and decreased cell density, increased mucopolysaccharide and “rising tide” phenomenon appeared. The fibrocartilage in the PIT24 and PIT120 groups was significantly thicker than that in the control group (P < 0.05). The ratio of collagen type I/III was significantly decreased in the PIT24 and PIT48 groups compared with the control group (P < 0.05), and the highest in the PIT72 group. The expression level of vascular endothelial growth factor in the PIT48, PIT72 and PIT96 groups was significantly higher than that in the control group (P < 0.05). The muscle tension was negatively correlated with the collagen ratio (r=-0.538; P < 0.01) and chondrocyte density (r=-0.570; P < 0.01), while muscle hardness was positively correlated with the expression level of vascular endothelial growth factor (r=0.613; P < 0.01). Our results suggest that different resting time makes significant differences in the PPTJ healing and the 72-hour resting is the best choice. Moreover, muscular properties are related to the cell density, collagen synthesis and growth factor expression, which can be used as a non-invasive indicator to guide post-injury training and prevent recurrence.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

Key words: Patella, Sports Medicine, Wound Healing, Muscles

CLC Number:

R318

Liang Xiao-tian1, Wang Bo1, Zeng Xiao-hui1, Tang Yi-ni1, Xiao Fang-xin1, Li Hai-wei2, Wang Lin3. Effect of different resting time on patella-patellar tendon healing after acute injury[J]. Chinese Journal of Tissue Engineering Research, 2017, 21(12): 1805-1812.

Figures/Tables 2

2.1 实验动物数量分析实验选用新西兰大白兔40只，分为6组，实验过程无脱失，全部进入结果分析。 2.2 组织形态学描述 2.2.1 苏木精-伊红染色图2显示：空白对照组细胞形态正常，轮廓清晰，有明显的“潮线”，胶原纤维整齐有序、呈波浪状排列(图2a，d)；与空白对照组相比，针刺后24 h组细胞轮廓不清，软骨细胞变形，胶原纤维分离、变直(图2b，e)；针刺后48 h组潮线消失，出现明显的软骨岛，胶原排列变直消融(图2c，f)；针刺后72 h组潮线周围模糊不清，细胞排列零散，胶原纤维不连续(图2g，j)；针刺后96 h组潮线虽然可见，但仍能观察到明显的细胞排列紊乱与波浪状排列消失(图2h，k)；针刺后120 h组呈现出较规则的骨腱结合部轮廓，但是细胞密度显著低于空白对照组，潮线明显向肌腱方向上涨(图2i，l)。 2.2.2 番红染色图3显示：空白对照组中黏多糖蛋白沿骨腱结合部均匀分布(图3a，d)；与空白对照组相比，针刺后24 h组(图3b，e)与针刺后120h组(图3i，l)明显增多；针刺后48 h组(图3c，f)和针刺后72 h组(图3g，j)结构完整，黏多糖蛋白含量也较为接近空白对照组，针刺后96 h组阳性染色面积则明显减少(图3h，k)。 2.3 组织学/免疫组织化学定量指标与空白对照组的纤维软骨带厚度相比，针刺后24 h组和针刺后120 h组显著增加(P < 0.01)，针刺后72 h组显著低于针刺后24 h组(P < 0.05)但与其他各训练组无显著性差异。最低值出现在针刺后96 h组，其显著低于针刺后24 h组，针刺后48 h和针刺后120 h组(P < 0.01)，见表1。空白对照组软骨细胞密度显著高于针刺后24 h组(P < 0.01)，针刺后48 h(P < 0.01)，针刺后72 h(P < 0.01)，针刺后96 h (P < 0.01)和针刺后120 h组(P < 0.05)。在各实验组中，仅针刺后48 h组低于针刺后120 h组有统计学上的意义(P < 0.05)，见表1。针刺后72 h组的Ⅰ型胶原表达显著高于其他各组(P < 0.01)，且其他各组之间无显著性差异。针刺后48 h组的Ⅲ型胶原表达量达到峰值，分别是空白对照组的301%(P < 0.01)，针刺后72 h组的187%(P < 0.01)，针刺后96 h组的235%(P < 0.01)和针刺后120 h组的190%(P < 0.01)。第二高值出现在针刺后24 h组，也显著高于空白对照组(P < 0.01)，针刺后72 h组(P < 0.05)，针刺后96 h组(P < 0.01)和针刺后120 h组(P < 0.05)。与空白对照组相比，针刺后24 h组和针刺后48 h组的Ⅰ型胶原与Ⅲ型胶原的比值(后文简述为“胶原比值”)明显偏低(P < 0.05)。针刺后72 h组的胶原比值分别是针刺后24 h组的448%(P < 0.05)及针刺后48 h组的404%(P < 0.05)。针刺后48 h，针刺后72 h和针刺后96 h组的血管内皮生长因子表达量分别是空白对照组的222%，329%和232%(P < 0.01)，针刺后72 h组显著高于其他所有组(P < 0.05)，见表2。 2.4 肌张力及肌肉硬度重复测量方差分析结果显示伤后不同时间恢复训练与时间并无交互关系(P > 0.05)。主体间比较显示肌张力随时间变化呈线性特征(P < 0.05)，见图4A，主体内比较显示肌张力在各组之间的差异有统计学意义(P < 0.05)。 LSD检验显示针刺后24 h，针刺后48 h，针刺后72 h，针刺后96 h，针刺后120 h组的肌张力分别为空白对照组的140%，149%，127%，126%和134%(P < 0.01)。球形检验及Greenhouse-Geisser校正测试显示肌肉硬度在4周测试中不全相同，在各组间存在显著性差异(P < 0.05)。在伤后训练1周时相对于针刺后24 h和针刺后48 h组，针刺后 96 h和针刺后120 h组的肌肉硬度有明显的升高；但训练4周结束时各伤后训练组之间则未见统计学意义上的差异 (P > 0.05)，见表3。 4周训练的肌张力平均值与Ⅲ型胶原存在中等相关关系(r=0.501；P < 0.01)，与细胞密度(r=-0.570；P < 0.01)及胶原比值(r=-0.538；P < 0.01)存在负相关，而肌肉硬度与血管内皮生长因子表达量存在中等相关关系(r=0.613； P < 0.01)，见图4B。"

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