局部注射肝素钠兔跟腱系统生物力学性质的变化

背景:跟腱腱围炎会导致跟腱生物力学特性的改变,目前以局部注射肝素钠治疗较为普遍,但其对跟腱生物力学特性影响的报道甚少。目的:观察跟腱劳损后生物力学性质及黏弹性的变化,同时验证肝素钠对跟腱生物力学特性及黏弹性的影响。设计、时间及地点:于2005-03/12在四川省骨科医院生物力学实验室完成随机对照动物实验。材料:50只成年日本大耳白兔,体质量(4.10±0.23)kg,用于制备跟腱劳损动物模型。方法:50只动物随机分为对照组(n=20)、训练组(n=12)和肝素钠组(n=18)。动物3周运动训练后继续训练,同时开始跟腱腱围及跟腱止点的肝素局部注射,2次/周。6周后进行跟腱的循环蠕变和应力松弛测定,最后进行跟腱的断裂实验。主要观察指标:测定不同运动后跟腱的生物力学特性及黏弹性的变化,包括跟腱的横截面积、循环蠕变、滞后环、应力松弛、强度特性和应力-应变。结果:训练组和肝素钠组动物的滞后环明显减小,应力松弛加快。训练后跟腱的屈服载荷及能量、断裂能量、屈服应力、应变能力明显高于对照组。肝素钠组所有生物力学指标都得到改善。结论:大强度运动可使跟腱的黏弹性下降,局部注射肝素钠可改善跟腱的强度特性和黏弹性。劳损后跟腱腱围和跟腱止点局部注射肝素钠对改善跟腱系统的强度特性和黏弹性有益。     

应用改良的环扣式传感器进行在体跟腱生物力学测试

背景：在体肌腱的生物力学测试国内报道较少。目的：探讨在体跟腱的生物力学行为。设计：随机对照实验研究。地点和对象：实验在武汉大学生物医学工程实验室完成，对象为新西兰大耳白兔45只，雌雄不限，体质量1．85～3．25kg(由武汉大学医学院动物室提供)。干预：对环扣式传感器进行改良，选择45只兔随机分3组，正常左侧跟腱组，正常右侧跟腱组，失胫神经支配的左侧跟腱组，以改良环式传感器分别对3组的跟腱进行生物学测试。实验和结果由两位有经验的专家检测。主要观察指标：跟腱张力曲线，张力波峰值，时间，冲量。结果：家兔跑跳时的张力曲线主要有4种即Ⅰ，Ⅱ，Ⅲ，Ⅳ，失胫神经失配状态下的一侧跟腱的生物力学参数[F3=(8．82±3．75)N，冲量=(37．95±14．86)N·ms]明显低于常态[F3=(16．75±5．65)N，冲量=(110．20±62．96)N·m8，P<0．05]。结论：改良环扣式传感器用于在体跟腱的生物力学测试具有可行、稳定、灵敏等优点。     

反复冻融处理同种异体移植兔跟腱组织学及生物力学变化

背景:近年来反复冻融处理技术作为一种同种异体肌腱的保存处理方法,主要原理是反复利用0～-60℃腱细胞最易损伤的冷冻温度,使得肌腱内细胞无活性,从而降低免疫原性.目的:拟观察反复冻融处理对同种异体移植兔跟腱组织学和生物力学的影响.设计、时间及地点:组织形态学及生物力学水平的对照动物实验,于2007-10/2008-02在北京大学运动医学研究所实验室完成.材料:选用17只成年健康新西兰大白兔.方法:无菌条件下取兔跟腱并带0.6 cm×0.4 cm跟骨骨块,按照组织库程序行60Co照射68 min,照射剂量为25 kGy.分为3组,-80 ℃冷冻,室温融解,反复冻融次数分别是1,3和10次,每组又抽取7条肌腱作生物力学测定,4条作组织学观察.主要观察指标:取肌腱行苏木精-伊红染色、胶原Van Gieson染色和透射电镜扫描,观察跟腱组织形态学改变,并进行跟腱拉伸实验以观察生物力学变化.结果:组织学观察发现,随着反复冻融次数的增加,腱束和胶原纤维捧列变得混乱直至断裂,细胞崩解,并且由于冰晶形成造成明显的腱束间裂隙.生物力学方面,与冻融1次组比较,冻融3,10次组的最大载荷、最大载荷能量及最大应力均显著降低(P<0.05),其他指标如弹性模量、能量密度也有下降但不明显.结论:反复冻融处理肌腱是一种有创的处理方法,正如组织学表现的可以引起细胞崩解、腱纤维紊乱甚至断裂等,最终会导致其生物力学水平的下降.     

应用改良的环扣式传感器进行在体跟腱生物力学测试

背景在体肌腱的生物力学测试国内报道较少.目的探讨在体跟腱的生物力学行为.设计随机对照实验研究.地点和对象实验在武汉大学生物医学工程实验室完成,对象为新西兰大耳白兔45只,雌雄不限,体质量1.85～3.25kg(由武汉大学医学院动物室提供).干预对环扣式传感器进行改良,选择45只兔随机分3组,正常左侧跟腱组,正常右侧跟腱组,失胫神经支配的左侧跟腱组,以改良环式传感器分别对3组的跟腱进行生物学测试.实验和结果由两位有经验的专家检测.主要观察指标跟腱张力曲线,张力波峰值,时间,冲量.结果家兔跑跳时的张力曲线主要有4种即Ⅰ,Ⅱ,Ⅲ,Ⅳ,失胫神经失配状态下的一侧跟腱的生物力学参数[F3=(8.82±3.75)N,冲量=(37.95±14.86)N·ms]明显低于常态[F3=(16.75±5.65)N,冲量=(110.20±62.96)N·ms,P＜0.05].结论改良环扣式传感器用于在体跟腱的生物力学测试具有可行、稳定、灵敏等优点.     

不同训练方式对大鼠跟腱改建的影响

目的：观察大鼠跟腱在不同应力作用模式下发生的适应性变化。方法：120只8周龄Wistar大鼠按不同强度方式分组训练。训练结束后测量跟腱生物力学性能。结果：跟腱的生物力学性能出现由下降到上升的动态变化。循环训练8周组的大鼠跟腱各项力学性能有明显的提升。结论：跟腱力学性质的变化是对重复应力刺激的一种反应，是肌腱对抗力学疲劳的机制。训练中负荷重复的次数比单次负荷本身的大小对肌腱的改建更具有积极意义。循环训练可以加速跟腱的塑形改建，是一种良好的锻炼方式。     

短期局部注射激素大鼠肌腱的生物力学和病理学变化

背景:研究证实激素长期局部注射对肌腱是有负面影响的,但短期应用激素对肌腱的影响仍存在争议.目的:观察短期激素局部注射后大鼠肌腱生物力学和病理方面的变化.方法:激素封闭对照组、激素封闭训练组大鼠均按人体局部封闭疗程进行治疗,于双侧跟腱的腱周部位注射与人体相当剂量地塞米松0.025 mg,1次/周,3次为1个疗程方法.激素封闭训练组保证跑步训练,跑步强度为25 m/min,30 min/次,3次/周.正常对照组大鼠自由活动,无任何处理.分别于第4,7周取肌腱行苏木精-伊红染色和MASSON染色,观察炎细胞浸润及胶原纤维排列情况,并进行跟腱拉伸实验以观察其生物力学变化.结果与结论:激素封闭对照组力学性能呈明显先增强后下降的趋势,并出现1例肌腱断裂实例,而激素封闭训练组力学性能呈明显先下降后恢复的趋势,两组病理均表现为肌腱退变.提示短期激素局部注射对肌腱是一种刺激,可使肌腱的适应性下降,应用时需避免强体力劳动,可进行适度功能锻炼.     

探讨局部压迫对预防低分子肝素钠注射后局部出血的作用

目的:探讨注射低分子肝素钠后压迫穿刺点对注射部位局部出血的影响.方法:将69例冠心病介入治疗的患者,按克赛治疗时间先后随机分为实验组34例和对照组35例.实验组注射拔针后压迫穿刺点3 min,对照组不压迫.观察每次注射部位皮下出血情况,比较两种拔针方法的差异性.结果:实验组共注射476次,对照组共注射490次.实验组产生轻度瘀斑12次,中度瘀斑12次,重度瘀斑12次,血肿4次;对照组产生轻度瘀斑32次,中度瘀斑19次,重度瘀斑22次,血肿18次.两组比较,在轻度瘀斑、重度瘀斑、血肿方面有统计学差异(P<0.01).结论:低分子肝素钠皮下注射拔针后,穿刺点压迫3 min可降低注射局部皮下出血的发生率和严重程度.     

探讨局部压迫对预防低分子肝素钠注射后局部出血的作用

目的:探讨注射低分子肝素钠后压迫穿刺点对注射部位局部出血的影响。方法:将69例冠心病介入治疗的患者,按克赛治疗时间先后随机分为实验组34例和对照组35例。实验组注射拔针后压迫穿刺点3min,对照组不压迫。观察每次注射部位皮下出血情况,比较两种拔针方法的差异性。结果:实验组共注射476次,对照组共注射490次。实验组产生轻度瘀斑12次,中度瘀斑12次,重度瘀斑12次,血肿4次;对照组产生轻度瘀斑32次,中度瘀斑19次,重度瘀斑22次,血肿18次。两组比较,在轻度瘀斑、重度瘀斑、血肿方面有统计学差异(P<0.01)。结论:低分子肝素钠皮下注射拔针后,穿刺点压迫3min可降低注射局部皮下出血的发生事和严重程度。     

探讨局部压迫对预防低分子肝素钠注射后局部出血的作用

目的：探讨注射低分子肝素钠后压迫穿刺点对注射部位局部出血的影响。方法：将69例冠心病介入治疗的患者，按克赛治疗时间先后随机分为实验组34例和对照组35例。实验组注射拔针后压迫穿刺点3min，对照组不压迫。观察每次注射部位皮下出血情况，比较两种拔针方法的差异性。结果：实验组共注射476次，对照组共注射490次。实验组产生轻度瘀斑12次，中度瘀斑12次，重度瘀斑12次，血肿4次；对照组产生轻度瘀斑32次，中度瘀斑19次，重度瘀斑22次，血肿18次。两组比较，在轻度瘀斑、重度瘀斑、血肿方面有统计学差异（P〈0．01）。结论：低分子肝索钠皮下注射拔针后，穿刺点压迫3min可降低注射局部皮下出血的发生率和严重程度。     

跟腱损伤修补后的运动疗法:组织学及生物力学评价

背景:开放性跟腱断裂修复后康复时间长、并发症多、功能恢复不尽人意.目前尚缺乏系统、科学、简便、易行的运动疗法促进康复.目的:观察运用运动疗法对跟腱损伤修补后的组织形态学和力学特性的影响.方法:日本大耳白兔48只,随机分成制动组和运动组,在距跟腱止点2.0 cm处切断跟腱,建立跟腱损伤模型,缝合线缝合腱周组织后,制动组使用石膏绷带进行传统的重力垂足位长腿石膏固定;运动组不予固定处理.术后7,14,21d分别取跟腱标本,观察肌腱粘连情况及最大断裂应力.结果与结论:制动组肌腱粘连较运动组明显(P<0.05).正常运动组跟腱的最大断裂应力明显高于制动组(P<0.05).说明在肌腱愈合的过程中,早期给予动态应力刺激,对促进组织的愈合,减少后遗症等十分有利.     

Static and dynamic biomechanical properties of the regenerating rabbit Achilles tendon

BACKGROUND: Since tendons show viscoelastic behavior, dynamic viscoelastic properties should be assessed in addition to static biomechanical properties. We evaluated differences between static and dynamic biomechanical properties of the regenerating rabbit Achilles tendon following tenotomy. METHODS: At 3, 6, or 12 weeks after right Achilles tenotomy, the right (regenerating) and left (control) tendons were collected with the calcaneus from 49 rabbits. A unidirectional failure test and a dynamic viscoelastic test were conducted. FINDINGS: Tensile strength and Young's modulus (static biomechanical properties) in the regenerating group at Week 6 were significantly greater than at Week 3, while at Week 12, these were significantly greater than at Week 6. However, even at Week 12, both parameters were less than in the control group. The value of tan delta represents dynamic viscoelasticity, a smaller tan delta indicates greater elasticity. tan delta for the regenerating group was significantly greater than for the control group at Week 3, but regenerating and control groups did not significantly differ at Week 6. No marked change was seen from Weeks 6 to 12 in the regenerating group, and no significant difference in tan delta was evident between the regenerating and control groups at Week 12. INTERPRETATION: Dynamic biomechanical properties of regenerating rabbit Achilles tendons may improve more rapidly than static biomechanical properties. Ability to tolerate dynamic movement in the healing Achilles tendon may improve more rapidly than ability to withstand static stresses.     

Mechanical properties of the human Achilles tendon, in vivo

Background

Ultrasonography has been widely applied for in vivo measurements of tendon mechanical properties. Assessments of human Achilles tendon mechanical properties have received great interest. Achilles tendon injuries predominantly occur in the tendon region between the Achilles-soleus myotendinous junction and Achilles-calcaneus osteotendinous junction i.e. in the free Achilles tendon. However, there has been no adequate ultrasound based method for quantifying the mechanical properties of the free human Achilles tendon. This study aimed to: 1) examine the mechanical properties of the free human Achilles tendon in vivo by the use of ultrasonography and 2) assess the between-day reproducibility of these measurements.

Methods

Ten male subjects had the Achilles tendon moment arm length, Achilles tendon cross sectional area and free Achilles tendon length determined. All subjects performed isometric plantarflexion ramp contractions to assess between-day reproducibility on two separate days. Simultaneous ultrasonography based measurements of Achilles-soleus myotendinous junction and Achilles-calcaneus osteotendinous junction displacement together with Achilles tendon force estimates yielded free Achilles tendon mechanical properties.

Findings

Free Achilles tendon maximal force, deformation and stiffness were 1924 (SD 229) N, 2.2 (SD 0.6) mm and 2622 (SD 534) N/mm on day 1. For between-day reproducibility there were no significant differences between days for free Achilles tendon mechanical properties. The between-day correlation coefficient and typical error percent were 0.81 and 5.3% for maximal Achilles tendon force, 0.85 and 11.8% for maximal Achilles tendon deformation and 0.84 and 8.8% for Achilles tendon stiffness respectively. Last, osteotendinous junction proximal displacement on average contributed with 71 (SD 12) % of proximal myotendinous junction displacement.

Interpretation

This study, for the first time, presents an ultrasonography based in vivo method for measurement of free AT mechanical properties. The method is applicable for evaluation of free human Achilles tendon mechanical properties in relation to training, injury and rehabilitation.     

电针促进钝器伤后家兔腓肠肌生物力学属性恢复的作用和机制研究

目的:探讨电针足三里+阿是穴促进急性钝器伤后家兔腓肠肌生物力学属性恢复的作用和相关机制。方法:将60只新西兰大白兔随机分为正常组、自然愈合组、电针组,制作家兔腓肠肌急性钝器伤模型,电针组给予足三里+阿是穴穴位电刺激(0.4m A,2Hz,15min),自然愈合组不予针刺治疗,自然愈合。分别于损伤后各时间点(7d、14d、28d、42d)取材、进行腓肠肌的拉伸试验,检测腓肠肌极限载荷、屈服载荷、极限强度、屈服强度、杨氏模量等生物力学指标的变化。结果:与自然愈合组比较,在损伤后第28天电针组极限载荷、屈服载荷显著大于自然愈合组(P0.05),极限强度、屈服强度经治疗后也较自然愈合组更强(P0.05),基本接近于正常组(P0.05);杨氏模量是反映腓肠肌刚度性能的重要指标,电针组也明显大于自然愈合组(P0.05)。结论:电针足三里+阿是穴能够有效促进家兔腓肠肌急性钝器伤后生物力学属性的恢复,损伤后治疗28天时效果最好。其机制可能与电针促进肌纤维再生、微观结构的恢复、促进毛细血管网的重建有关。     

Effects of static stretching on mechanical properties and collagen fiber orientation of the Achilles tendon in vivo

BackgroundThe study was designed to examine changes in tendon properties measured during ramp and ballistic contractions after static stretching and to elucidate the relationship between stretching-induced changes in tendon properties (particularly hysteresis) and collagen fiber orientation.MethodsThirteen males performed static stretching, in which the ankle was passively flexed to 36° dorsiflexion and remained stationary for 10 min. Before and after stretching, the stiffness and hysteresis of tendon structures in the medial gastrocnemius muscle were measured using ultrasonography during ramp and ballistic contractions. Tendon collagen fiber orientation was also estimated from the coefficient of variation (CV) of echogenicity on transverse ultrasonic images of the Achilles tendon.Findings.The hysteresis of tendon structures significantly decreased by 15.5% (p = 0.005) during ramp contractions and by 15.3% (p = 0.003) during ballistic contractions after stretching, whereas stiffness did not. The mean echogenicity of the Achilles tendon significantly increased by 6.0% (p = 0.002) after stretching, whereas the CV of echogenicity did not (p = 0.148). Furthermore, the relative change in mean echogenicity, which reflected interstitial fluid movement within tendons, tended to be correlated to that in hysteresis measured during ballistic contractions (r = 0.439, p = 0.133).InterpretationThese results suggest that the hysteresis, but not stiffness, of tendon structures measured during ramp and ballistic contractions significantly decreased after stretching. Furthermore, a decline in the hysteresis of tendon structures after static stretching was associated with interstitial fluid movement within tendons, but not to changes in collagen fiber orientation.     

Effects of stress deprivation on mechanical properties of the in situ frozen-thawed semitendinosus tendon in rabbits

OBJECTIVE: To clarify the effect of complete stress deprivation on the mechanical properties of the in situ frozen-thawed semitendinosus tendon, an idealized autograft model. DESIGN: Ninety-six rabbits were divided into three groups. In the frozen group (n=36), we applied the freeze-thaw treatment to the semitendinosus tendon to necrotize fibroblasts in the tendon. In the frozen and stress-shielded group (n=30), after we applied the same freeze-thaw treatment to the tendon, we completely released the tendon from stress. In the sham group (n=30), a sham operation was applied. In each group, 6 rabbits were sacrificed at 0 (only in the frozen group), 1, 2, 3, 6 and 12 weeks after surgery. BACKGROUND: Previous studies have not clarified remodeling of the semitendinosus autograft in ligament reconstruction or its idealized model. METHODS: The tendon was frozen with liquid nitrogen. The tendon was released from stress with the originally developed technique using a polyester tape. In each period, 5 out of the 6 rabbits were evaluated with tensile testing, and the remaining rabbit was histologically observed. RESULTS: Complete stress shielding significantly increased the cross-sectional area of the frozen-thawed tendon at 1 and 2 weeks, while it significantly inhibited the increase of the area due to the freeze-thaw treatment at 3 and 6 weeks. Complete stress shielding significantly reduced material properties of the frozen-thawed tendon after 2 weeks. CONCLUSIONS: The frozen-thawed semitendinosus tendon has unique remodeling characteristics under a stress-shielded condition, which were not the same as those of the frozen-thawed patellar tendon. RELEVANCE: Remodeling of the semitendinosus tendon autograft under stress-shielded conditions may be different from that of the patellar tendon autograft.     

Effects of foot orthoses on Achilles tendon load in recreational runners

Background

Achilles tendon pathology is a frequently occurring musculoskeletal disorder in runners. Foot orthoses have been shown to reduce the symptoms of pain in runners but their mechanical effects are still not well understood.

Methods

This study aimed to examine differences in Achilles tendon load when running with and without orthotic intervention. Twelve male runners ran at 4.0 m·s^− 1. Ankle joint moments and Achilles tendon forces were compared when running with and without orthotics.

Findings

The results indicate that running with foot orthotics was associated with significant reductions in Achilles tendon load compared to without orthotics.

Interpretation

In addition to providing insight into the mechanical effects of orthotics in runners, the current investigation suggests that via reductions in Achilles tendon load, foot orthoses may serve to reduce the incidence of chronic Achilles tendon pathologies in runners.     

Biomechanics of the Achilles tendon

Purpose. Tendons behave viscoelastically and exhibit adaptive responses to conditions of increased loading and disuse. Strain patterns in tendons may not be uniform, as tendons show stress-shielded areas and areas subjected to compressive loading at the enthesis. These areas correspond to the sites where tendinopathic characteristics are typically seen.

Method. We review the biomechanic literature on Achilles tendon, trying to interpret it on the basis that classic inflammatory changes are not frequently seen in chronic athletic tendon conditions.

Results. Biomechanical studies show that the strains within the tendons near their insertion site are not uniform. If the material properties are similar throughout the tendon, forces transferred through the insertion site preferentially load the side of the tendon that is usually not affected initially in tendinopathy. In that case, the side affected by tendinopathy is generally ‘stress shielded’.

Conclusion. The presence of differential strains opens the possibility of alternative biomechanical explanations for the pathology found in these regions of the tendon. The traditional concept of tensile failure may not be the essential feature of the pathomechanics of insertional tendinopathy. Additional work is needed ascertain whether such principles should be incorporated in current rehabilitation.     

Endoscopic surgery of the Achilles tendon

The value of endoscopic surgery as a minimally invasive treatment is well recognized and includes less perioperative pain, less scarring, minimal blood loss, and faster recovery. While open surgery on the Achilles tendon is notorious for wound complications, the tendon is situated in a well-formed tunnel allowing surgical procedures to be performed endoscopically. Various endoscopic techniques have been successfully applied to the treatment of non-insertional Achilles tendinopathy, Haglund's syndrome, Achilles tendon rupture, and equinus contracture. Although the evidence is currently limited, results from authors acquainted with the techniques have been encouraging. Both an understanding of surgical anatomy of the hindfoot and familiarity in soft tissue endoscopy are required to achieve successful outcomes while minimizing complications.