双蒂腓肠肌皮瓣修复跟腱复合缺损的改进及其解剖学依据

目的改进双蒂腓肠肌皮瓣下滑术式,细化其修复跟腱复合组织缺损适应证,减少供区创伤。方法0侧成人下肢标本,模拟只切断比目鱼肌近端附着点、保留跟腱远端完整性的双蒂腓肠肌V-Y推进皮瓣,测定膝关节不同屈曲角度下皮瓣下滑的距离。结果在膝关节屈曲0°、30°、60°、90°时,上述方法后双蒂腓肠肌皮瓣下滑的平均距离分别为(13.83±5.31)mm、(25.00±2.83)mm、(32.67±4.41)mm、(39.50±4.85)mm。结论双蒂腓肠肌V-Y下滑术式中只切断比目鱼肌近端附着点后重建,保留跟腱远端完整性的这一改进在解剖学上是可行的,适用于40mm以内的成人跟腱复合组织缺损。     

Distribution patterns of fibre types in the triceps surae muscle group of chimpanzees and orangutans

Different locomotor and postural demands are met partly due to the varying properties and proportions of the muscle fibre types within the skeletal muscles. Such data are therefore important in understanding the subtle relationships between morphology, function and behaviour. The triceps surae muscle group is of particular interest when studying our closest living relatives, the non-human great apes, as they lack a significant external Achilles tendon, crucial to running locomotion in humans and other cursorial species. The aim of this study, therefore, was to determine the proportions of type I (slow) and type II (fast) fibres throughout these muscles in chimpanzees and orangutans using immunohistochemistry. The orangutan had a higher proportion of type I fibres in all muscles compared with the chimpanzees, related to their slower, more controlled movements in their arboreal habitat. The higher proportion of type II fibres in the chimpanzees likely reflects a compromise between their need for controlled mobility when arboreal, and greater speed and power when terrestrial. Overall, the proportion of slow fibres was greater in the soleus muscle compared with the gastrocnemius muscles, and there was some evidence of proximal to distal and medial to lateral variations within some muscles. This study has shown that not only do orangutans and chimpanzees have very different muscle fibre populations that reflect their locomotor repertoires, but it also shows how the proportion of fibre types provides an additional mechanism by which the performance of a muscle can be modulated to suit the needs of a species.     

Musculotendon excursion potential,tendon slack and muscle fibre length: the interaction of the canine gastrocnemius muscle and tendon

Although the form‐function relation of muscles and tendons has been studied extensively, little in vivo data exist on the musculotendon properties of the gastrocnemius complex in dogs. Using a combination of ultrasound and 3D motion tracking, musculotendon parameters were obtained in vivo from the lateral gastrocnemius muscle and the gastrocnemius tendon in nine healthy Labrador Retrievers. These parameters include musculotendon length and excursion potential, tendon slack length, muscle belly length, muscle fibre length, pennation angle and architectural index. This study also examined the variation of muscle and tendon length contributions to musculotendon length, as well as the relation between musculotendon excursion potential and muscle fibre length or tendon length. To facilitate comparison between dog breeds, the femur length as a potential scaling parameter was examined. In the Labrador gastrocnemius musculotendon complex, the tendon contributes 41% (± 9%) of musculotendon length. In longer musculotendon complexes, the contribution of the muscle belly increases while the tendon contribution decreases. Longer muscle belly and musculotendon complexes were, however, associated with shorter muscle fibres. No significant relations were found between musculotendon excursion potential and muscle fibre length or tendon slack length, and femur length did not prove to be a reliable scale factor for the length‐related musculotendon parameters examined in this study. Longer musculotendon complexes exhibit relatively longer muscle bellies, which are in turn associated with shorter muscle fibre lengths. This trade‐off between gastrocnemius muscle belly length and muscle fibre length might have the advantage that muscle volume stays constant regardless of the length of the limbs.     

Anatomic variations of the musculotendinous junction of the soleus muscle and its clinical implications

The soleus muscle, like the gastrocnemius, is a powerful plantarflexor muscle in the lower limb. The soleus muscle joins the aponeurosis of the gastrocnemius muscle to form the calcaneal (Achilles) tendon. While the basic anatomy of the soleus muscle has been previously described, no study has addressed the anatomical variations of its distal attachment. We found considerable anatomic variation in the distance between this musculotendinous junction and the most proximal point of the proximal edge. This distal measuring point was defined as the most proximal point of the proximal edge of the posterior surface of the calcaneal tuberosity. Eighty human cadaver specimens were preserved according to Thiel's method; we examined one limb from each cadaver, studying 80 lower extremities in total. Following careful dissection of the lower limb, we measured the distance between the distal point of attachment of the soleus muscle fibers (the musculotendinous junction) and the designated measuring point. Our findings were divided into three groups: Group 1 (10 cases, 12.5%), where the distance between the musculotendinous junction and the designated point on the calcaneal tuberosity was between 0 and 1 inches; Group 2 (56 cases, 70%), where the distance was between 1 and 3 inches; and Group 3 (14 cases, 17.5%), where the distance was greater than 3 inches. Detailed knowledge of the anatomic variations of the soleus muscle at its insertion point onto the calcaneal tendon has clinical implications in calcaneal tendon repair following rupture and in the planning of reconstructive surgery using soleus muscle flaps.     

Application of shear wave elastography for the gastrocnemius medial head to tennis leg

Muscle strain of the gastrocnemius medial head mainly occurs at the musculotendinous junction (MTJ), and stiffness is a risk factor. Shear wave elastography (SWE) measures elasticity by determining the propagation velocity. The aim of this study was to measure the elasticity of the normal muscle and aponeurosis in the MTJ of the gastrocnemius medial head using SWE, thus obtaining information relevant to muscle strain at this point. Forty‐one volunteers (82 legs) were recruited and the gastrocnemius medial heads were examined at four points: three on the aponeurosis, namely at the center of the MTJ (Central), 10 mm proximal to it (Proximal) and 10 mm distal to it (Distal); and at one on the muscle belly (Muscle). The measurements were compared among the points, between males and females, and between younger and middle‐aged subjects. Correlations between the elastic modulus and age were also examined. The elastic moduli at Proximal, Central, Distal, and Muscle were 2.82 ± 0.53 m/s, 3.43 ± 0.83 m/s, 4.83 ± 1.56 m/s, and 2.25 ± 0.43 m/s, respectively. These values differed significantly among the points of the aponeurosis, Distal having the highest modulus followed by Central. The elastic moduli were significantly greater in males than females at Distal and Muscle and in younger subjects than middle‐aged subjects at Muscle. No significant correlations between elastic modulus and age were observed for any point. SWE could be a feasible method for quantifying the elasticity of muscle and aponeurosis in the MTJ of the gastrocnemius medial head. Clin. Anat. 30:114–119, 2017. © 2016 Wiley Periodicals, Inc.     

运动后针刺腓肠肌干预肥胖大鼠肌腱退行性病变

背景:运动后腓肠肌张力升高是导致退行性病变的主要原因,超重者的发病风险更高,通过针刺腓肠肌可以降低运动后腓肠肌张力.目的:观察通过针刺运动后力学生长因子和组织蛋白表达变化,从而探讨针刺腓肠肌对跟腱退行性病变风险的影响.方法:32只12周龄雄性SD大鼠给予高脂饲料喂养4周建立肥胖大鼠模型,体质量(500.27±29.11...     

短期负荷下p38抑制剂对兔髌腱及止点炎症因子的影响

背景:p38抑制剂干预治疗相关疾病已经取得了很好的成效,但是关于短期大强度负荷下p38抑制剂对兔髌腱及髌骨髌腱结合部中炎性反应的影响仍有许多疑问。目的:在实验室建立的定量跳跃动物模型上,观察短期内大强度运动负荷下,p38抑制剂对兔髌腱及髌骨髌腱结合部中主要炎性因子白细胞介素1β、白细胞介素6和转化生长因子β1表达的影响。方法:34只18周龄新西兰大白兔,随机分为对照组(n=4)、跳跃组1,3,5 d(n=5)及跳跃+p38抑制剂组1,3,5 d(n=5)。各跳跃组进行电刺激跳跃训练,每次电刺激引发兔向前上方跳跃,跳跃高度达到10 cm定义为合格,每次训练共进行150次合格跳跃。跳跃+p38抑制剂组在每次训练后腹腔注射SB203580(0.5 mg/kg),对照组不训练,预适应过程及饲养时间相同。各组训练结束后麻醉处死取材,采用SABC法对组织进行免疫组织化学染色,并通过Metamorph图形处理软件对各炎症因子的阳性细胞密度进行定量计算。结果与结论:①髌腱及髌骨髌腱结合部中白细胞介素1β、白细胞介素6和转化生长因子β1的免疫组化结果显示,短期大强度负荷运动下髌腱及髌骨髌腱结合部的炎症因子变化情况不一致;②与跳跃组相比,跳跃+p38抑制剂组髌腱与髌骨髌腱结合部中3个炎症因子白细胞介素1β、白细胞介素6和转化生长因子β1的表达水平均没有显著变化(P>0.05);③结果提示大强度运动后急性期p38抑制剂可能不会影响髌腱及腱止点的炎症反应。     

双蒂腓肠肌皮瓣下滑修复跟腱及皮肤缺损的应用解剖学

目的:为双蒂腓肠肌皮瓣下滑修复小腿下端皮肤及跟腱缺损和术前判断肌皮瓣能修复的范围提供解剖学理论依据。方法:30侧下肢标本,模拟腓肠肌皮瓣的切取,观察双蒂腓肠肌皮瓣中腓肠肌及其神经、血管的形态和毗邻关系,观测肌皮瓣能向下滑动的距离。结果:腓肠肌的动脉有4种类型:Ⅰ.腓肠内、外侧动脉单独发支,占56.7％;Ⅱ.腓肠内、外侧动脉单独发支,而一侧有来源于对侧动脉的分支直接人肌,占23.3％;Ⅲ.腓肠内、外侧动脉共干占10％;Ⅳ.腓肠内、外侧动脉单独发支,但有一侧为两支,占10％。神经分支形式有6种类型:Ⅰ.腓肠内侧皮神经、腓肠肌内外侧头肌支、比目鱼肌支单独发支,占36.7％;Ⅱ.腓肠内侧皮神经和腓肠肌内侧头肌支共干,占20％;Ⅲ.腓肠肌外侧头肌支与比目鱼肌支共干,占20％;Ⅳ腓肠内侧皮神经与腓肠肌内侧头肌支共干,腓肠肌外侧头肌支与比目鱼肌支共干,占13.3％;Ⅴ.腓肠内侧皮神经、腓肠肌内外侧头肌支、比目鱼肌支共干,占6.7％;Ⅵ.腓肠内侧皮神经、腓肠肌内、外侧头肌支共干,占33％。皮瓣向下滑动的平均最大距离为(9.2±0.9)cm。结论:双蒂腓肠肌皮瓣适合于修复跟腱及皮肤同时缺损,切取时需要注意神经、血管有不同的类型并做相应的处理,肌皮瓣能修复的平均最大长度为(9.2±0.9)cm。     

In vivo dynamics of human medial gastrocnemius muscle‐tendon complex during stretch‐shortening cycle exercise

The purpose of this study was to investigate the dynamics of human muscle‐tendon complex (MTC) during stretch‐shortening cycle exercises through in vivo observation. A total of seven male subjects performed dorsi flexion followed by plantar flexion at two different frequencies, 0.3 Hz (slow) and 1.0 Hz (fast), in a toe‐standing position. The fascicle length (L_F) of the medial gastrocnemius muscle during the movements was determined using a real‐time ultrasonography in vivo. The L_F at the switching phase from dorsi to plantar flexion was significantly shorter in the fast exercise (54.4 ± 5.5 mm) than in the slow one (58.2 ± 5.4 mm), suggesting that the elongation of tendon structures at that time was significantly greater in the former than in the latter. Furthermore, at the initial stage of plantar flexion during the fast movement, the L_F hardly changed with a rapid shortening of tendon structures at that time. The observed relation between MTC length and force showed that the behaviour of tendon structures contributed to 20.2 and 42.5% of the total amount of work completed during plantar flexion phase in the slow and fast movements, respectively. Thus, the present results suggest that tendon structures make the dynamics of MTC more efficient during stretch‐shortening cycle exercises by changing their lengths.     

Muscle architecture and passive lengthening properties of the gastrocnemius medialis and Achilles tendon in children who idiopathically toe-walk

Children who idiopathically toe-walk (ITW) habitually operate at greater plantarflexion angles and thus, at shorter muscle-tendon unit (MTU) lengths than typically developing (TD) children. Therefore, it is often assumed that habitual use of the gastrocnemius muscle in this way will cause remodelling of the muscle-tendon architecture compared to TD children. However, the gastrocnemius muscle architecture of children who ITW has never been measured. It is essential that we gain a better understanding of these muscle-tendon properties, to ensure that appropriate clinical interventions can be provided for these children. Five children who ITW (age 8 ± 2 years) and 14 TD children (age 10 ± 2 years) participated in this study. Ultrasound was combined with isokinetic dynamometry and surface electromyography, to measure muscle architecture at common positions and passive lengthening properties of the gastrocnemius muscle and tendon across full range of motion. Regardless of which common condition groups were compared under, both the absolute and normalised to MTU muscle belly and fascicle lengths were always longer, and the Achilles tendon length was always shorter in children who ITW than TD children (p < 0.05; large effect sizes). The passive lengthening properties of the muscle and tendon were not different between groups (p > 0.05); however, passive joint stiffness was greater in children who ITW at maximum dorsiflexion (p = 0.001) and at a joint moment common to all participants (p = 0.029). Consequently, the findings of this pilot study indicate a remodelling of the relative MTU that does not support the concept that children who ITW commonly experience muscle shortening. Therefore, greater consideration of the muscle and tendon properties are required when prescribing clinical interventions that aim to lengthen the MTU, and treatments may be better targeted at the Achilles tendon in children who ITW.     

Patellar tendon lengthening and augmentation with quadriceps tendon graft for treatment of severe patella infera

BackgroundPatella infera represents a permanent abnormally low position of the patella with three characteristics: distal position of the patella in the femoral trochlea, permanent shortening of the patellar tendon, and decreased distance between the inferior pole of the patella and the articular surface of the tibia. Several surgical techniques have been described to resolve this disabling condition with varying outcomes.HypothesisLengthening of the shortened patellar tendon with augmentation using a quadriceps tendon graft in combination with excessive intra-articular release improve knee function in patients presenting with severe and permanent patella infera.MethodsNine patients (four males, five females) with significant patella infera were treated between 2004 and 2020. The low position of the patella was documented using the Caton–Deschamps index. The Tegner Lysholm knee scoring scale and the Numerical Rating Scale (NRS) for pain were used as outcome measures before surgery and at follow up. Complete data were available in 100% of cases at 12 months follow up, and in 78% at final follow up.ResultsThe average follow up was 4.2 years (range, 1–16 years). The Tegner Lysholm score improved from a mean preoperative score of 43.8 to a mean postoperative score of 80.5. The median NRS status decreased from an average of 6.7 (range, 5–8) to 2.3 (range, 1–7). The median preoperative flexion was 103.3° (range, 40–125°), rising to 126.6° (range, 40–145°). The median preoperative Caton–Deschamps ratio of 0.32 (range, 0–0.6) improved to 0.99 (range, 0.9–1.1) at final follow up. Two patients needed additional surgical treatment (arthroscopic scar tissue removal and proximalisation of the tibial tuberosity).ConclusionLengthening of a shortened patellar tendon with augmentation using a quadriceps tendon graft combined with excessive intra-articular release is an individually adapted surgical salvage procedure to treat permanent patella infera. It improves knee function and yields good to excellent results in most cases.     

带腓肠肌肌腱的腓肠神经营养血管复合皮瓣修复跟腱并皮肤缺损

目的探讨带腓肠肌肌腱的腓肠神经营养血管复合皮瓣修复跟腱并皮肤缺损的效果。方法复合皮瓣修复跟腱并皮肤缺损6例,其中3例跟腱背侧部分缺损,2例跟腱内侧部分缺损,1例跟腱完全缺损。切取带腓肠肌肌腱的腓肠神经营养血管复合皮瓣时,保持肌腱与皮瓣深筋膜的联系。皮瓣大小7cm×5cm～11cm×10cm,腓肠肌肌腱大小为5cm×3cm～9cm×4cm。结果6例皮瓣均完全成活,感染控制;6例术后随访3～50个月,皮瓣外观满意,无跟腱再断裂者。患侧踝关节屈伸范围基本正常,功能评定,优5例,良1例。结论带腓肠肌肌腱的腓肠神经营养血管复合皮瓣修复跟腱并皮肤缺损具有手术操作简单,术后跟腱粘连轻,功能恢复好的优点。     

Dissecting the accessory soleus muscle: a literature review, cadaveric study, and imaging study

The accessory soleus muscle (ASM) has been an unusual anatomical variant since its first recordings in Guy's Hospital Reports of the early nineteenth century. Individuals with an ASM may present with symptoms of pain and/or swelling and were often misdiagnosed as soft-tissue tumors such as hemangioma, sarcoma, or lipoma. The aim of our study was threefold: (1) to review the cadaveric and clinical literature to determine the reported prevalence of ASM; (2) to conduct a cadaveric study investigating the prevalence and attachment sites of the ASM; (3) to conduct a retrospective analysis of magnetic resonance imaging (MRI) of patients presenting with ankle symptoms to determine prevalence and attachment sites of the ASM. Our findings demonstrated that the prevalence of the muscle (3%) was as stated in the literature (0.7-5.5%), but with males more likely to possess unilateral ASM and females more likely to possess bilateral ASM. Three common attachment types were reported in the literature: (i) a distal attachment to the medial aspect of the calcaneus by a separate tendon (26.1% of ASM subjects), (ii) a distal tendinous attachment to the calcaneal tendon (3.5%), and (iii) a distal fleshy attachment to the medial surface of the calcaneus (4.3%), with the remaining 66.1% of ASM subjects from previous studies with unidentified attachment types. Our cadaveric specimens were found to possess each attachment type, whereas imaging patients all possessed distal attachments to the medial calcaneus via a separate tendon. Furthermore, a rare cadaveric specimen with two distal attachments was also found. We believe it is important to recognize the prevalence of this condition and be aware of its morphology in order to understand its clinical presentation, accurately diagnose the condition, and pursue effective forms of management.     

The arterial supply of the long head of biceps tendon: Anatomical study with implications for tendon rupture

Zones of hypovascularity are thought to exist in several tendons of the shoulder, contributing to localized tendon weakness and subsequent rupture in clinical practice. Although these zones have been demonstrated in many frequently ruptured tendons, the existence of a similar area in the often ruptured long head of biceps (LHB) tendon is largely unknown. Twenty cadaveric upper limb specimens were dissected after injection with either a radio‐opaque lead oxide/milk mixture or India ink, followed by histological sectioning of the tendons. The LHB tendon was consistently supplied via its osteotendinous and musculotendinous junctions by branches of the thoracoacromial and brachial arteries respectively. In two specimens, additional branches from the anterior circumflex humeral artery travelling in a mesotenon vascularized the midsection of tendon. These source arteries divided the LHB tendon into either two or three vascular territories, depending upon the presence of the mesotenon‐derived vascular supply. A zone of hypovascularity was consistently found in the region of the LHB tendon most frequently prone to rupture. This zone covered an area 1.2–3 cm from the tendon origin, extending from midway through the glenohumeral joint to the proximal inter‐tubercular groove. This hypovascular region occurred on the border of two adjacent vascular territories, where reduced caliber choke vessels provide limited arterial supply. While it is probable that the limited arterial supply contributes to the susceptibility of this area to rupture, similar to other tendons the true pathogenesis is likely to be a combination of both vascular and mechanical factors. Clin. Anat. 23:683–692, 2010. © 2010 Wiley‐Liss, Inc.     

取腱器配合腓肠肌筋膜瓣翻转术治疗跟腱断裂疗效观察

目的介绍利用取腱器切取腓肠肌筋膜瓣,翻转缝合断裂跟腱的临床效果。方法选取2008年1月~2012年12月我院跟腱断裂病人21例,男15例,女6例,平均年龄33.5岁,为剧烈运动后跟腱撕裂伤,均采用手术治疗。俯卧位,跟腱断裂部位纵行手术切口,马尾状撕裂部位梳理整齐后编织缝合,根据需要腱膜的长度于切口近端相应部位作纵行小切口,用取腱器取筋膜条,自皮下隧道牵出远端切口,翻转,光滑面朝后加固缝合断裂跟腱。术后长腿石膏固定4周,短腿石膏固定2周。结果 21例患者均获得术后随访,平均随访时间2.3年(1~5年)。根据Arner Lindholm评分标准,优16例,良4例,差1例,优良率95.2%。结论取腱器微创小切口下取腓肠肌腱膜方法具有小切口,创伤小,美观等优点,术后正规康复功能锻炼后临床效果良好。     

The arterial supply of the patellar tendon: Anatomical study with clinical implications for knee surgery

The middle‐third of the patellar tendon (PT) is well‐established as a potential graft for cruciate ligament reconstruction, but there is little anatomical basis for its use. Although studies on PT vascular anatomy have focused on the risk to tendon pedicles from surgical approaches and knee pathophysiology, the significance of its blood supply to grafting has not been adequately explored previously. This investigation explores both the intrinsic and extrinsic arterial anatomy of the PT, as relevant to the PT graft. Ten fresh cadaveric lower limbs underwent angiographic injection of the common femoral artery with radio‐opaque lead oxide. Each tendon was carefully dissected, underwent plain radiography and subsequently schematically reconstructed. The PT demonstrated a well‐developed and consistent vascularity from three main sources: antero‐proximally, mainly by the inferior‐lateral genicular artery; antero‐distally via a choke‐anastomotic arch between the anterior tibial recurrent and inferior medial genicular arteries; and posteriorly via the retro‐patellar anastomotic arch in Hoffa's fat pad. Two patterns of pedicles formed this arch: inferior‐lateral and descending genicular arteries (Type‐I); superior‐lateral, inferior‐lateral, and superior‐medial genicular arteries (Type‐II). Both types supplied the posterior PT, with the majority of vessels descending to its middle‐third. The middle‐third PT has a richer intrinsic vascularity, which may enhance its ingrowth as a graft, and supports its conventional use in cruciate ligament reconstruction. The pedicles supplying the PT are endangered during procedures where Hoffa's fat pad is removed including certain techniques of PT harvest and total knee arthroplasty. Clin. Anat. 22:371–376, 2009. © 2009 Wiley‐Liss, Inc.     

The arterial anatomy of the Achilles tendon: Anatomical study and clinical implications

The Achilles tendon is the most frequently ruptured tendon in the lower limb and accounts for almost 20% of all large tendon injuries. Despite numerous published studies describing its blood supply, there has been no uniformity in describing its topography. The current study comprises a detailed anatomical study of both the intrinsic and extrinsic arterial supply of the Achilles tendon, providing the detail sought from studies calling for improved planning of surgical procedures where damage to the vascularity of the Achilles tendon is likely. A dissection, microdissection, histological, and angiographic study was undertaken on 20 cadaveric lower limbs from 16 fresh and four embalmed cadavers. The Achilles tendon is supplied by two arteries, the posterior tibial and peroneal arteries. Three vascular territories were identified, with the midsection supplied by the peroneal artery, and the proximal and distal sections supplied by the posterior tibial artery. The midsection of the Achilles tendon was markedly more hypovascular that the rest of the tendon. The Achilles tendon is at highest risk of rupture and surgical complications at its midsection. Individuals with particularly poor supply of the midsection may be at increased risk of tendon rupture, and approaches to the tendon operatively should consider the route of supply by the peroneal artery to this susceptible part of the tendon. Clin. Anat. 22:377–385, 2009. © 2009 Wiley‐Liss, Inc.     

Differential strain patterns of the human gastrocnemius aponeurosis and free tendon,in vivo

Aim: The mechanical characteristics of the human free tendon and aponeurosis, in vivo, remains largely unknown. The present study evaluated the longitudinal displacement of the separate free Achilles tendon and distal (deep) aponeurosis of the medial gastrocnemius muscle during voluntary isometric contraction. Methods: Ultrasonography‐obtained displacement of the free tendon and tendon–aponeurosis complex, electromyography of the gastrocnemius, soleus, and dorsiflexor muscles, and joint angular rotation were recorded during isometric plantarflexion (n = 5). Tendon cross‐sectional area, moment arm and segment lengths (L_o) were measured using magnetic resonance imaging. Tendon force was calculated from joint moments and tendon moment arm, and stress was obtained by dividing force by cross‐sectional area. The difference between the free tendon and tendon–aponeurosis complex deformation yielded separate distal aponeurosis deformation. Longitudinal aponeurosis and tendon strain were obtained from the deformations normalized to segment lengths. Results: At a common tendon force of 2641 ± 306 N, the respective deformation and L_o were 5.85 ± 0.85 and 74 ± 0.8 mm for the free tendon and 2.12 ± 0.64 and 145 ± 1.3 mm for the distal aponeurosis, P < 0.05. Longitudinal strain was 8.0 ± 1.2% for the tendon and 1.4 ± 0.4% for the aponeurosis, P < 0.01. Stiffness and stored energy was 759 ± 132 N mm^?1 and 6.14 ± 1.89 J, respectively, for the free tendon. Cross‐sectional area of the Achilles tendon was 73 ± 4 mm², yielding a stress of 36.5 ± 4.6 MPa and Young's modulus of 788 ± 181 MPa. Conclusion: The free Achilles tendon demonstrates greater strain compared with that of the distal (deep) aponeurosis during voluntary isometric contraction, which suggests that separate functional roles may exist during in vivo force transmission.