Efficacy and mechanism of botulinum toxin type A combined with static progressive stretching in the treatment of traumatic knee stiffness in rats
10.3760/cma.j.cn501098-20240904-00542
- VernacularTitle:A型肉毒毒素联合静态渐进性牵伸治疗大鼠创伤性膝关节僵硬的效果及其机制
- Author:
Ke CHEN
1
;
Xin ZHANG
;
Kai REN
;
Yingying LIAO
;
Xin HE
;
Xiaoju LI
Author Information
1. 四川省骨科医院（国家中医康复中心建设单位，四川省中医康复医院）康复科，成都 610041
- Publication Type:Journal Article
- Keywords:
Botulinum toxins;
Knee injuries;
Fibrosis;
Static stretching
- From:
Chinese Journal of Trauma
2025;41(2):201-211
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the efficacy and mechanism of botulinum toxin type A (BTX-A) combined with static progressive stretching (SPS) in the treatment of traumatic knee stiffness in rats.Methods:Forty healthy male SD rats aged 8 weeks and weighing 220-300 g, were randomly divided into blank control group ( n=8) and model groups ( n=28) (including injury group, BTX-A group, SPS group and BTX-A+SPS group, with 7 in each group). Hlidebrand′s method was used to construct a traumatic knee stiffness model, with the following main steps: destruction of the joint capsule, Kirschner wire fixation, joint drilling, and removal of the internal fixation at 4 weeks. The blank control group did not receive any treatment and could move freely in the cage. The injury group moved freely after successful modeling. On the day of internal fixation removal, BTX-A was injected into the joint cavity in group BTX-A, SPS treatment was started in the SPS group, BTX-A was injected into the joint cavity and SPS treatment was started in the BTX-A+SPS group. The treatments lasted 16 days. The range of motion (ROM) and joint stiffness were measured before treatment and at 16 days after treatment. At 16 days after treatment, knee joint tissue was collected and the rats were sacrificed, and the articular capsule fibrous tissue proliferation was observed by HE and Masson staining. The expression levels of phosphorylated (p)-Smad2, Smad2, p-Smad3, Smad3, Smad4, transforming growth factor-β1 (TGF-β1), collagen type I, collagen type III, and α-smooth actin (α-SMA) were determined by Western blot. The ratio of phosphorylated protein to total protein was calculated to reflect the phosphorylation level. Results:(1) ROM: Before treatment, the ROM in the blank control group was significantly higher than that in the other groups ( P<0.05), with no significant difference in ROM among the other groups ( P>0.05). At 16 days after treatment, ROM in the injury group, BTX-A group, SPS group, and BTX-A+SPS group was lower than that in the blank control group ( P<0.05), among which ROM in the BTX-A+SPS group was significantly higher than that in the injury group, BTX-A group, and SPS group ( P<0.05). At 16 days after treatment, there was no significant difference in ROM before and after treatment in the blank control group ( P>0.05), and ROM in the other groups was significantly increased compared with that before treatment ( P<0.01). (2) Joint stiffness: At 16 days after treatment, the joint stiffness levels in the injury group, the BTX-A group, and the SPS group were (0.95±0.24)N·cm/°, (0.86±0.22)N·cm/°, and (0.65±0.09)N·cm/° respectively, which were significantly lower than (0.36±0.03)N·cm/° in the blank control group ( P<0.05). The joint stiffness level of the BTX-A+SPS group was (0.49±0.04)N·cm/°, which was not significantly different from that in the blank control group ( P>0.05), but was significantly lower than those in the injury group, BTX-A group, and SPS group ( P<0.05). (3) Fibrous tissue proliferation: at 16 days after treatment, the joint capsular structure in the blank control group was complete and clear, the fibers were arranged in order, and there was no obvious fibrous tissue proliferation. The pathological changes in the injury group were the most serious, with a large number of synovial fibrous tissue proliferation, significantly increased blood vessels in the tissue, and inflammatory cell infiltration. Compared with the SPS group and BTX-A group, the lesions in BTX-A+SPS group were milder, with only slight increase in the number of synovial cells but no obvious vascular proliferation or lymphocytes, and the overall lesions were the least severe. (4) Protein expression: the ratios of p-Smad2/Smad2 in the injury group, BTX-A group and SPS group were 1.552±0.234, 1.328±0.272 and 1.194±0.277 respectively, which were higher than 0.794±0.082 in the blank control group ( P<0.05). The ratio of p-Smad2/Smad2 in the BTX-A+SPS group was 1.013±0.123, which was not significantly different from those in the blank control group, BTX-A group or SPS group ( P>0.05), but was lower than that in the injury group ( P<0.05). At 16 days after treatment, the p-Smad3/Smad3 ratios in the injury group, BTX-A group, SPS group and BTX-A+SPS group were 2.272±0.309, 1.664±0.285, 1.381±0.276 and 1.003±0.060 respectively, which were higher than 0.515±0.051 in the blank control group ( P<0.05). The p-Smad3/Smad3 ratio in the BTX-A+SPS group was significantly lower than those in the injury group, BTX-A group and SPS group ( P<0.05). At 16 days after treatment, the level of Smad4 in the injury group (1.001±0.015) was higher than 0.294±0.076 in the blank control group ( P<0.05). However, there was no significant difference between the BTX-A group (0.664±0.051), SPS group (0.833±0.045), BTX-A+SPS group (0.467±0.068) or the blank control group ( P>0.05). The level of Smad4 in the BTX-A+SPS group was significantly lower than those in the injury group, BTX-A group and SPS group ( P<0.05). At 16 days after treatment, the level of TGF-β1 in the injury group (1.004±0.407) was higher than 0.269±0.122 in the blank control group ( P<0.05), while there was no significant difference between the BTX-A group (0.564±0.194), SPS group (0.422±0.086) and BTX-A+SPS group (0.347±0.161) and the blank control group ( P>0.05). The level of TGF-β1 in the BTX-A+SPS group was significantly lower than those in the injury group, BTX-A group and SPS group ( P<0.05). At 16 days after treatment, the level of type I collagen in the injury group was 0.999±0.170, higher than 0.299±0.139 in the blank control group ( P<0.05), while there was no significant difference between the BTX-A group (0.542±0.278), SPS group (0.561±0.165), and BTX-A+SPS group (0.537±0.045) and the blank control group ( P>0.05). The level of collagen type I in the BTX-A+SPS group was significantly lower than those in the injury group, BTX-A group, and SPS group ( P<0.05). At 16 days after treatment, the level of type III collagen in the injury group was 1.002±0.126, higher than 0.239±0.106 in the blank control group ( P<0.05), while there was no significant difference between the BTX-A group (0.661±0.062), SPS group (0.595±0.062), and BTX-A+SPS group (0.504±0.269) and the blank control group ( P>0.05). The level of collagen type III in the BTX-A+SPS group was significantly lower than those in the injury group, BTX-A group, and SPS group ( P<0.05). At 16 days after treatment, the level of α-SMA in the injury group was 0.998±0.074, higher than 0.130±0.023 in the blank control group ( P<0.05), while there was no significant difference between the BTX-A group (0.358±0.060), SPS group (0.432±0.230), and BTX-A+SPS group (0.293±0.135) and the blank control group ( P>0.05). The level of α-SMA in the BTX-A+SPS group was significantly lower than those in the injury group, BTX-A group and SPS group ( P<0.05). Conclusions:Compared with single treatment, the combination of BTX-A and SPS demonstrates significantly greater efficacy in the treatment of traumatic knee stiffness in rats. This combined approach not only enhances joint mobility and elasticity but also effectively inhibits joint capsule fibrosis. The underlying mechanism may involve the further suppression of TGF-β1 expression in the joint capsule, leading to reduced phosphorylation levels of Smad2 and Smad3. This, in turn, inhibits the binding of Smad2 and Smad3 to the Smad4 receptor, ultimately downregulating the expression of the downstream proteins of the TGF-β/Smad signaling pathway, such as collagen type I, collagen type III and α-SMA.
