骨质疏松兔松质骨微观结构和微观成分的时间序贯性变化

目的:研究去势手术建立骨质疏松兔模型中松质骨微观结构和微观成分的时间序贯性变化。方法:40只新西兰白兔随机分为假手术组(sham组,n=20)和骨质疏松组(OP组,n=20)。OP组兔子给予去势手术处理,sham组给予假手术处理。分别于术后的0周、4周、6周、8周,利用DXA测量腰椎骨密度(每组每个时间点选择5只动物)。之后处死动物,采集腰椎标本。利用Micro-CT、FTIR、腰椎轴向压缩试验得到松质骨的微观结构、微观成分(骨矿盐晶体和胶原)和宏观力学参数。利用t检验比较同一时间点两组之间的相关参数。结果:OP组BMD逐渐下降,松质骨微观结构逐渐疏松,微观组成属性逐渐改变,宏观力学强度均逐渐下降。FTIR在4周时即检测到OP组腰椎骨矿盐和胶原基质比(P=0.046)、骨矿盐结晶度(P=0.018)、胶原交联比(P=0.006)发生显著性改变,早于BMD和微观结构的变化。OP组腰椎宏观生物力学强度在第8周时达到最低点(P=0.001)。结论:去势手术后,腰椎松质骨骨矿盐晶体和胶原属性最早发生变化,松质骨微观成分和微观结构的改变是导致椎体强度明显改变的原因。FTIR技术可以较早的检测到骨质疏松发生过程中骨组织微观成分的改变。     

剖宫产子宫肌层单层锁边缝合术

目的:评价剖宫产子宫下段横切口缝合技术及子宫肌层单层锁边缝合的可行性。方法:选取我院2008年12月至2010年12月剖宫产病例1920例,940例采用连续加褥式包埋缝合子宫,为对照组;980例采用子宫肌层单层锁边缝合术,为试验组。结果:试验组总手术时间为(28.08±4.15)min,对照组总手术时间为(36.25±5.67)min,两组比较,差异有统计学意义(p<0.01);试验组术后排气时间为(16.10±8.29)h,对照组术后排气时间为(24.26±4.28)h,差异有统计学意义(p<0.05);试验组术中出血量为(210±60)ml,显著低于对照组(280±50)ml,差异有统计学意义(p<0.01);试验组拆线时切口感染率为0.2%,对照组拆线时切口感染率为1%,差异有统计学意义(p<0.05)。而切皮至胎儿娩出时间、新生儿Apgar评分、人均输血量、术后体温一次>38℃、术后三天体温<37℃五项指标比较,两组差异无统计学意义(p>0.05)。结论:子宫肌层单层锁边缝合优于连续加褥式包埋缝合术,进一步提高了产科手术操作技术水平,值得临床推广应用。     

背带式缝合术治疗剖宫产产后出血的疗效和安全性分析

目的:考察背带式缝合术治疗剖宫产产后出血患者的临床疗效和安全性。方法:对照组行常规止血方式治疗;观察组行背带式缝合术治疗,比较两组患者临床疗效和并发症发生率。结果:观察组产后出血疗效显著优于对照组(P0.05);产后出血量显著低于对照组(P0.01);出血持续时间和治疗时间均显著短于对照组(P0.01);并发症的例数明显低于对照组(P0.01)。结论:背带式缝合术对剖宫产产后出血患者的临床效果显著,安全有效。     

小骨窗微创手术治疗高血压脑出血患者的疗效

目的:分析小骨窗微创手术在高血压脑出血患者的临床效果。方法:选取我院收治的高血压脑出血患者200例,按照治疗方式的不同分为观察组100例,对照组100例,观察组采用小骨窗微创手术治疗,对照组采用传统开颅手术治疗,对两组疗效及预后进行对比。结果:两组患者的术后残留血肿量较术前明显减少,差异有统计学意义(P0.05),观察组术后残留血肿量(10.3±2.8)m L,对照组术后残留血肿量(11.1±3.0)m L,两组之间术后血肿残留量比较,差异无统计学意义(P0.05)。观察组手术时间(92.8±15.5)分钟,对照组手术时间(125.4±16.1)分钟,观察组手术时间明显短于对照组,差异有统计学意义(P0.05)。观察组住院时间(15.8±5.2)天,对照组住院时间(24.1±5.8)天,观察组住院时间明显短于对照组,差异有统计学意义(P0.05)。再出血率比较:观察组治疗后再出血率3.0%,对照组治疗后再出血率8.0%,观察组出血率明显低于对照组,差异有统计学意义(P0.05)。NDS及ADL比较:两组治疗后NDS及ADL均优于治疗前,差异有统计学意义(P0.05)。观察组NDS及ADL均显著优于对照组,差异有统计学意义(P0.05)。GCS比较:两组评分差异无统计学意义(P0.05)。结论:小骨窗微创手术可以改善患者的预后,可显著提高高血压脑出血治疗效果。     

全膝关节置换术使用不可吸收线加强缝合内侧关节囊对术后髌骨倾斜的影响

目的:分析比较在初次全膝关节置换术(TKA)中使用不可吸收线加强缝合髌骨内侧关节囊对术后髌骨倾斜的影响。方法:本研究回顾性分析了从2014年12月至2017年9月期间在我院治疗的22例随访资料齐全的初次全膝关节置换的患者资料,根据术中是否使用不可吸收线加强缝合内侧关节囊,将患者分为普通组和加强缝合组,普通组12例,加强缝合组10例。通过患者手术前后的X线片测量髋膝踝角(HKA)、Insall-Salviti指数(ISR)、髌骨倾斜角(PTA),采用美国膝关节协会(KSS)评分评价患者手术前后膝关节功能。比较两组患者手术前以及术后1个月、术后末次随访时HKA、ISR、PTA以及KSS评分等指标。结果:普通组患者KSS评分、ROM、HKA,术后有明显改善(P0.05),其中ROM在术后末次随访时改善更为显著;PTA术后较术前增大(P0.05);ISR手术前后无明显差异(P0.05)。加强缝合组患者KSS评分、ROM,在术后1个月时无明显提升(P0.05),但在术后末次随访时提升明显(P0.05)。PTA术后较术前减小(P0.05)。HKA、ISR手术前后无明显差异(P0.05)。无论在术后1个月还是术后末次随访时,加强缝合组PTA都小于普通组(P0.05)。结论:在使用内侧髌旁入路的TKA中,使用不可吸收线加强缝合内侧关节囊可在一定程度上减小术后髌骨的倾斜,提升髌骨的稳定性,值得临床推广应用。     

贯穿式胰管空肠黏膜缝合在胰十二指肠切除术中的对比研究

目的:比较贯穿式胰管空肠黏膜缝合与传统缝合方式用于胰十二指肠切除术(PD)中的效果,并分析其用于PD术中的价值。方法:收集2010年9月-2015年12月我院行PD的60例病人临床资料,按照吻合方法的不同分为2组:贯穿组和传统组,各30例。贯穿组患者均采用贯穿式胰管空肠黏膜缝合,传统组患者均采取传统缝合的方式。对比两组患者临床一般指标(胰肠吻合时间、术中出血量和术后住院时间)以及围术期并发症(如胰瘘、淋巴漏、胃排空障碍、肺部感染、吻合口出血、腹腔脓肿)等情况,并比较两组再手术率和再入院率。结果:贯穿组胰肠吻合时间、术中出血量和术后住院时间较传统组减少,差异有统计学意义(P0.05)。贯穿组围术期胰瘘发生率为10.00%,显著低于传统组的40.00%,差异有统计学意义(P0.05),贯穿组B级胰瘘发生率显著低于传统组,差异有统计学意义(P0.05)。贯穿组再手术率、再入院率与传统组比较差异无统计学意义(P0.05)。结论:贯穿式胰管空肠黏膜缝有利于PD患者术后恢复,且围术期胰瘘发生率低,不失为一种有效的胰肠吻合方式。     

不同纤维桩表面处理方式对牙根修复后抗折裂强度的影响

目的:探讨不同纤维桩表面处理方式对牙根修复后抗折裂强度的影响。方法:收集行正畸拔除的前磨牙120颗作为本研究样本,随机将120个纤维桩分为对照组、喷砂组和过氧化氢酸蚀组,每组40例。对照组纤维桩表明不给予任何处理,喷砂组给予氧化铝砂粒持续喷砂粗化处理,过氧化氢酸蚀组给予10%过氧化氢溶液处理,均包埋于纤维桩道预备好的离体牙内,采用相同树脂制备成核,行全冠修复与黏固,再模拟口腔内部环境给予样本牙冷热循环处理,经相同环境加载后,置于电子万能实验机获取样本牙抗折裂强度数据。对比三组离体牙样本体型数据、离体牙断裂方式、抗折裂强度,对三组进行为期24个月的定期随访,统计三组修复体断裂率,并采用Kaplan-Meier曲线和Log Rank法分析三组的生存状况。结果:三组的离体牙样本关于牙齿长度、牙根长度、颈部颊舌径及颈部近远中径对比差异无统计学意义(P0.05);喷砂组和过氧化氢酸蚀组的离体牙抗折裂强度显著强于对照组(P0.05);喷砂组和过氧化氢酸蚀组的牙齿折裂总发生率分别为20.00%和22.50%,均显著低于对照组的70.00%(P0.05)。但两组间比较差异无统计学意义(P0.05)。喷砂组、过氧化氢酸蚀组的生存状况显著优于对照组。结论:前磨牙修复过程中,对纤维桩表面进行喷砂或过氧化氢酸蚀处理均能提高牙根修复后抗折裂强度,改善修复体修复效果生存状况,且两种纤维桩表面处理方式对离体牙样本的断裂方式和抗折裂强度影响相当。     

适量运动对大鼠跟腱复健有促进效应

本研究为比较不同运动量对大鼠跟腱修复的影响,采用54只8周大,体重200～250 g的SD雄性大鼠为实验对象。根据随机分组方式平均分成3组,每组18只:控制组、行走15 min组(15分组)、行走30 min组(30分组)。将54大鼠的右后脚跟腱切断,控制组不予任何运动干预,其余两组在手术处理后的第5天起,进行运动干预。每天运动1次,运动时间分别为15 min和30 min;前2天行走速度4.0 m/min;之后12.0m/min。分别在第5天、第12天、第19天、第28天评估跟腱功能指数(achilles function index, AFI);手术后第28天处死大鼠,取出跟腱,观察外观、胶原蛋白生长情况、断裂强度(最大破坏力量)(breaking strength, BS)、拉伸应力(tensile stress, TS)及恢复指数(recovery index, RI)。AFI值:结果显示,第12天30分组显著优于控制组和15分组,有统计学差异(p0.05);第28天,30分组显著优于控制组,有统计学差异(p0.05);而15分组无明显差异,不具有统计学意义(p0.05)。跟腱直径与胶原蛋白含量方面:各组受伤肢直径均显著大于自身正常肢,胶原蛋白含量更高;在各组小鼠的受伤肢中,30分组的跟腱直径显著小于控制组,差异具有统计学意义(p0.05);参与行走运动的组别受伤跟腱中胶原蛋白排列较整齐。断裂强度方面:控制组受伤肢显著大于正常肢,差异具有统计学意义(p0.05);受伤肢间均未达显著差异(p0.05)。拉伸应力方面:控制组受伤肢的跟腱断裂强度显著小于正常肢,差异具有统计学意义(p0.05);各组受伤肢间跟腱断裂强度均未有显著差异(p0.05)。恢复指数方面:3组间均未达显著差异,无统计学差异(p0.05)。本研究表明,在设定的模式下进行走路运动,可以促进新生胶原蛋白排列整齐,从而提升修复后的跟腱功能;虽然增加运动量并不能增强断裂强度,也不能提升拉伸应力,但可能会使大鼠提早适应受伤后的行动过程。     

腹腔镜下卵巢囊肿剥除术后缝合与电凝止血对卵巢功能的影响

目的:探究腹腔镜下卵巢囊肿剥除术后缝合与电凝止血对卵巢功能的影响。方法:选择2014年5月~2015年12月期间我院收治卵巢囊肿患者78例为研究对象,两组患者均行腹腔镜下卵巢囊肿剥除术,根据患者术中止血方式的不同将其分为观察组(41例)和对照组(37例);观察组术中采用双极电凝止血,对照组患者性术中采用缝合止血;观察并比较术后4周、12周两组患者促卵泡生长激素(FSH)、促黄体激素(LH)、雌二醇(E2)及窦状卵泡计数(Shape of sinus follicle count,AFC),对比两组术后12周卵巢功能恢复情况。结果:术后4周两组患者FSH、LH水平较术前升高,E2及AFC水平较术前降低,差异均有统计学意义(P0.05);术后12周对照组FSH、LH、E2及AFC水平与术前比较,差异无统计学意义(P0.05),观察组患者FSH、LH水平较术前升高,E2及AFC水平较术前降低,且观察组患者FSH、LH水平高于对照组,E2及AFC水平低于对照组,差异均有统计学意义(P0.05);术后12周,观察组患者出现排卵异常、经量过少及经期延长的发生率均高于对照组(P0.05)。结论:缝合止血在腹腔镜下卵巢囊肿剥除术止血对患者卵巢功能的损伤作用小于电凝止血,术后卵巢功能恢复快,临床上应当优选缝合止血,降低对卵巢功能的影响。     

微创PCCP与传统动力髋螺钉治疗老年股骨转子间骨折疗效比较

目的:比较微创PCCP与传统动力髋螺钉治疗老年股骨转子间骨折的疗效.方法:回顾性分析我院2010年1-2011年6月收治的老年股骨转子间骨折患者36例,根据治疗方法不同分为微创PCCP和传统动力髋螺钉组,比较两组的治疗效果.结果:两组切口长度(t=12.824,P＜0.05)、出血量(t=9.342,P＜0.05)、手术时间(t=6.209,P＜0.05)和住院时间(t=7.923,P＜0.05)比较,差异有统计学意义.两组髋关节Harris评分(t=1.038,P＞0.05)与并发症发生率(X2=0.929,P＞0.05)比较,差异无统计学意义.两组疗效进行比较,X2=4.213,P＜0.05,两组手术效果差异有统计学意义.结论:微创PCCP较传统动力髋螺钉治疗老年股骨转子间骨折的疗效更优,适合临床应用.     

Changes of calf muscle-tendon biomechanical properties induced by passive-stretching and active-movement training in children with cerebral palsy

Biomechanical properties of calf muscles and Achilles tendon may be altered considerably in children with cerebral palsy (CP), contributing to childhood disability. It is unclear how muscle fascicles and tendon respond to rehabilitation and contribute to improvement of ankle-joint properties. Biomechanical properties of the calf muscle fascicles of both gastrocnemius medialis (GM) and soleus (SOL), including the fascicle length and pennation angle in seven children with CP, were evaluated using ultrasonography combined with biomechanical measurements before and after a 6-wk treatment of passive-stretching and active-movement training. The passive force contributions from the GM and SOL muscles were separated using flexed and extended knee positions, and fascicular stiffness was calculated based on the fascicular force-length relation. Biomechanical properties of the Achilles tendon, including resting length, cross-sectional area, and stiffness, were also evaluated. The 6-wk training induced elongation of muscle fascicles (SOL: 8%, P = 0.018; GM: 3%, P = 0.018), reduced pennation angle (SOL: 10%, P = 0.028; GM: 5%, P = 0.028), reduced fascicular stiffness (SOL: 17%, P = 0.128; GM: 21%, P = 0.018), decreased tendon length (6%, P = 0.018), increased Achilles tendon stiffness (32%, P = 0.018), and increased Young's modulus (20%, P = 0.018). In vivo characterizations of calf muscles and Achilles tendon mechanical properties help us better understand treatment-induced changes of calf muscle-tendon and facilitate development of more effective treatments.     

Elastic properties of human Achilles tendon are correlated to muscle strength.

The purpose of this study was to investigate whether the mechanical properties of the Achilles tendon were correlated to muscle strength in the triceps surae in humans. Twenty-four men and twelve women exerted maximal voluntary isometric plantar flexion (MVIP) torque. The elongation (DeltaX) and strain of the Achilles tendon (epsilon), the proximal part of which is the composite of the gastrocnemius tendon and the soleus aponeurosis, at MVIP were determined from the displacement of the distal myotendinous junction of the medial gastrocnemius using ultrasonography. The Achilles tendon force at MVIP (F) was calculated from the MVIP torque and the Achilles tendon moment arm. There were no significant differences in either the F-DeltaX or F-epsilon relationships between men and women. DeltaX and epsilon were 9.8 +/- 2.6 mm and 5.3 +/- 1.6%, respectively, and were positively correlated to F (r = 0.39, P < 0.05; r = 0.39, P < 0.05), which meant that subjects with greater muscle strength could store more elastic energy in the tendon. The regression y-intercepts for the F-DeltaX (P < 0.01) and F-epsilon (P < 0.05) relationship were significantly positive. These results might indicate that the Achilles tendon was stiffer in subjects with greater muscle strength, which may play a role in reducing the probability of tendon strain injuries. It was suggested that the Achilles tendon of subjects with greater muscle strength did not impair the potential for storing elastic energy in tendons and may be able to deliver the greater force supplied from a stronger muscle more efficiently. Furthermore, the difference in the Achilles tendon mechanical properties between men and women seemed to be correlated to the difference in muscle strength rather than gender.     

Four Anchor Repair of Jersey Finger

BackgroundVarious surgical techniques for treating avulsions of the flexor digitorum profundus tendon at the distal phalanx have been published but no ideal technique has emerged. We introduce a new all-internal 4-anchor flexor tendon repair technique and evaluate outcomes in three clinical cases.MethodsIn this retrospective case series, we reviewed three patients that sustained an avulsion of the flexor digitorum profundus tendon at the distal phalanx. All patients were surgically treated with the four-anchor repair technique. Two titanium anchors were inserted into the distal phalanx and two all-suture anchors were inserted distal to the first set of anchors. The tendon was then attached to these four anchors using a Krackow stitch pattern and the anchors were sown to each other. Active flexion and extension of the proximal and distal interphalangeal joint were measured at 3-month, 12-month, and 5-year follow-up. Postoperative complications were documented.ResultsAll patients achieved excellent clinical outcomes according to assessment criteria. At 3-month follow-up, all patients regained full flexion; two patients had full extension, while one patient was 3 degrees short of full extension. At 12-month follow-up, all patients had full flexion and extension. Five-year follow-up demonstrated the same results with no loss of function, sensation or grip strength. The repairs healed without rupture, and no complications were reported.ConclusionThe 4-anchor flexor tendon repair is a viable surgical technique for zone 1 flexor digitorum profundus tendon repair or reconstruction. Further studies are needed to replicate these promising results and biomechanically validate this technique.Level of Evidence: IV     

Effect of vascular endothelial growth factor on rat Achilles tendon healing

This study evaluated the effect of exogenous vascular endothelial growth factor (VEGF) on tendon healing and regulation of other growth factors in a rat Achilles tendon model. Fifty Sprague-Dawley rats were used. In the experimental group, the left Achilles tendon was transected and repaired with the modified Kessler suture technique, and the right Achilles tendon was transected and repaired with resection of plantaris tendon. VEGF, 100 mul (50 mug/ml), was injected into each tendon at the repair site. The same surgical procedures were performed in the control group, with the same volume of saline injected into the repair sites. At intervals of 1, 2, and 4 weeks, the animals were killed and the tendons were harvested and evaluated for tensile strength (1, 2, and 4 weeks) and gene expression (postoperative day 4). At 1 week postoperatively, when plantaris tendon was preserved, the tensile strength of the repaired tendons with VEGF treatment (3.63 +/- 0.62 MPa) was significantly higher than the tensile strength of the repaired tendons with saline treatment (2.20 +/- 0.36 MPa). There was no difference in tensile strength between the two groups without the plantaris tendon support. At 2 weeks postoperatively, the tensile strength was 11.34 +/- 3.89 MPa in the group with VEGF treatment and plantaris tendon preservation, which was significantly higher than the tensile strength in the other groups. There was no significant difference in tensile strength among the groups at 4 weeks postoperatively. The gene expression showed that transforming growth factor-beta in the VEGF-treated tendon was up-regulated in the early stage of tendon healing, whereas expression of platelet-derived growth factor, basic fibroblast growth factor, and insulin-like growth factor-1 was not significantly different among the groups. In conclusion, administration of exogenous VEGF can significantly improve tensile strength early in the course of the rat Achilles tendon healing and was associated with increased expression of transforming growth factor-beta.     

The effect of running, strength, and vibration strength training on the mechanical, morphological, and biochemical properties of the Achilles tendon in rats.

Compared with muscle or bone, there is a lack of information about the relationship between tendon adaptation and the applied loading characteristic. The purpose of the present study was to analyze the effect of different exercise modes characterized by very distinct loading patterns on the mechanical, morphological, and biochemical properties of the Achilles tendon. Sixty-four female Sprague-Dawley rats were divided into five groups: nonactive age-matched control (AMC; n = 20), voluntary wheel running (RT; n = 20), vibration strength-trained (LVST; n = 12), high-vibration strength-trained (HVST; n = 6), and high strength-trained (HST; n = 6) group. After a 12-wk-long experimental period, the Achilles tendon was tested mechanically and the cross-sectional area, the soleus and gastrocnemius muscle mass, and mRNA concentration of collagen I, collagen III, tissue inhibitor of metalloproteinase-1 (TIMP-1), transforming growth factor-beta, connective tissue growth factor, and matrix metalloproteinase-2 was determined. Neither in the LVST nor in the HVST group could any adaptation of the Achilles tendon be detected, although the training had an effect on the gastrocnemius muscle mass in the LVST group (P < 0.05). In the HST group, the highest creep was found, but the effect was more pronounced compared with the LVST group (P < 0.05) than with the AMC group. That indicates that this was rather induced by the low muscle mass rather than by training. However, the RT group had a higher TIMP-1 mRNA concentration in the Achilles tendon in contrast to AMC group (P < 0.05), which suggests that this exercise mode may have an influence on tendon adaptation.     

Effect of Bone Mineral Density on Rotator Cuff Tear: An Osteoporotic Rabbit Model

IntroductionAn increased bone mineral density (BMD) in the proximity to tendon insertion can improve rotator cuff repair and healing. However, how a decrease of BMD in the humeral head affects the biomechanical properties of the rotator cuff tendon is still unclear. Previous studies have demonstrated ovariectomy in animals to lead to osteoporosis and decreased BMD, and Teriparatide (PTH) administration to improve BMD and strength of bone. This study aimed to explore the correlation between humeral head BMD and infraspinatus (ISP) tendon insertion strength, and if an increase in bone quantity of the humeral head can improve the strength of the rotator cuff.ResultsSignificant differences were observed in the measured humeral head BMD of the Control and OVX-PTH groups compared to the OVX-Saline group (P = 0.0004 and P = 0.0024, respectively). No significant difference was found in failure stress among the three groups, but an expected trend with the control group and OVX-PTH group presenting higher failure strength compared to the OVX-Saline group. BMD at the humeral head showed a positive linear correlation with stress (r² = 0.54). Histology results showed the superiority in OVX-PTH group ISP enthesis compared to the OVX-Saline group.ConclusionBone loss of the humeral head leads to decreased tendon/bone insertion strength of the infraspinatus tendon enthesis. Teriparatide administration can increase bone density of the humeral head and may improve the mechanical properties of the infraspinatus tendon enthesis.     

Conditioning of the Achilles tendon via ankle exercise improves correlations between sonographic measures of tendon thickness and body anthropometry

Although conditioning is routinely used in mechanical tests of tendon in vitro, previous in vivo research evaluating the influence of body anthropometry on Achilles tendon thickness has not considered its potential effects on tendon structure. This study evaluated the relationship between Achilles tendon thickness and body anthropometry in healthy adults both before and after resistive ankle plantarflexion exercise. A convenience sample of 30 healthy male adults underwent sonographic examination of the Achilles tendon in addition to standard anthropometric measures of stature and body weight. A 10-5 MHz linear array transducer was used to acquire longitudinal sonograms of the Achilles tendon, 20 mm proximal to the tendon insertion. Participants then completed a series (90-100 repetitions) of conditioning exercises against an effective resistance between 100% and 150% body weight. Longitudinal sonograms were repeated immediately on completion of the exercise intervention, and anteroposterior Achilles tendon thickness was determined. Achilles tendon thickness was significantly reduced immediately following conditioning exercise (t = 9.71, P < 0.001), resulting in an average transverse strain of -18.8%. In contrast to preexercise measures, Achilles tendon thickness was significantly correlated with body weight (r = 0.72, P < 0.001) and to a lesser extent height (r = 0.45, P = 0.01) and body mass index (r = 0.63, P < 0.001) after exercise. Conditioning of the Achilles tendon via resistive ankle exercises induces alterations in tendon structure that substantially improve correlations between Achilles tendon thickness and body anthropometry. It is recommended that conditioning exercises, which standardize the load history of tendon, are employed before measurements of sonographic tendon thickness in vivo.     

Effect of joint rotation correction when measuring elongation of the gastrocnemius medialis tendon and aponeurosis

It is well known that during maximal plantar flexion contractions the ankle joint rotation overestimates the actual elongation of the tendon and aponeurosis. The aim of this study was to examine the influence of the curve length changes of the Achilles tendon on the joint rotation corrected elongation and strain of the gastrocnemius medialis (GM) tendon and aponeurosis. Nine subjects (age: 29.4 ± 5.7 years, body mass: 78.8 ± 6.8 kg, body height: 178 ± 4 cm) participated in the study. The subjects performed maximal voluntary isometric plantarflexion contractions in the prone position on a Biodex-dynamometer. Ultrasonography (Aloka SSD 4000) was used to visualize the muscle belly of the GM muscle-tendon unit. To calculate the curve length changes of the Achilles tendon its surface contour was reconstructed using a series of small reflective skin markers having a diameter of 2.5 mm. The elongation of the GM tendon and aponeurosis was calculated (a) as the difference of the measured and the passive (due to joint rotation) displacement of the tendon and aponeurosis and (b) as the difference of the measured displacement and the length changes of the reconstructed Achilles tendon surface contour. The absolute difference between the elongation obtained by both methods were 1.2 ± 0.4 mm. These differences were due to the higher changes in length obtained by the reconstruction of the tendon curved surface contour as compared to the changes observed in the passive displacement of the digitised point at the aponeurosis. Without correcting for angle joint rotation, the measured elongation clearly overestimates the actual elongation of the GM tendon and aponeurosis. After the passive displacement correction the calculated elongation still overestimates the actual elongation of the GM tendon and aponeurosis. However, this overestimation has a negligible effect on the examined in vivo strain (0.3%) of the tendon and aponeurosis.