Structure of the Achilles tendon at the insertion on the calcaneal tuberosity

Findings on the twisting structure and insertional location of the AT on the calcaneal tuberosity are inconsistent. Therefore, to obtain a better understanding of the mechanisms underlying insertional Achilles tendinopathy, clarification of the anatomy of the twisting structure and location of the AT insertion onto the calcaneal tuberosity is important. The purpose of this study was to reveal the twisted structure of the AT and the location of its insertion onto the calcaneal tuberosity using Japanese cadavers. The study was conducted using 132 legs from 74 cadavers (mean age at death, 78.3 ± 11.1 years; 87 sides from men, 45 from women). Only soleus (Sol) attached to the deep layer of the calcaneal tuberosity was classified as least twist (Type I), both the lateral head of the gastrocnemius (LG) and Sol attached to the deep layer of the calcaneal tuberosity were classified as moderate twist (Type II), and only LG attached to the deep layer of the calcaneal tuberosity was classified as extreme twist (Type III). The Achilles tendon insertion onto the calcaneal tuberosity was classified as a superior, middle or inferior facet. Twist structure was Type I (least) in 31 legs (24%), Type II (moderate) in 87 legs (67%), and Type III (extreme) in 12 legs (9%). A comparison between males and females revealed that among men, 20 legs (24%) were Type I, 57 legs (67%) Type II, and eight legs (9%) Type III. Among women, 11 legs (24%) were Type I, 30 legs (67%) Type II, and four legs (9%) Type III. No significant differences were apparent between sexes. The fascicles of the Achilles tendon attach mainly in the middle facet. Anterior fibers of the Achilles tendon, where insertional Achilles tendinopathy is most likely, are Sol in Type I, LG and Sol in Type II, and LG only in Type III. This suggests the possibility that a different strain is produced in the anterior fibers of the Achilles tendon (calcaneal side) where insertional Achilles tendinopathy is most likely to occur in each type. We look forward to elucidating the mechanisms generating insertional Achilles tendinopathy in future biomedical studies based on the present results.     

The Effect of the Achilles Tendon on Trabecular Structure in the Primate Calcaneus

Humans possess the longest Achilles tendon relative to total muscle length of any primate, an anatomy that is beneficial for bipedal locomotion. Reconstructing the evolutionary history of the Achilles tendon has been challenging, in part because soft tissue does not fossilize. The only skeletal evidence for Achilles tendon anatomy in extinct taxa is the insertion site on the calcaneal tuber, which is rarely preserved in the fossil record and, when present, is equivocal for reconstructing tendon morphology. In this study, we used high‐resolution three‐dimensional microcomputed tomography (micro‐CT) to quantify the microstructure of the trabecular bone underlying the Achilles tendon insertion site in baboons, gibbons, chimpanzees, and humans to test the hypothesis that trabecular orientation differs among primates with different tendon morphologies. Surprisingly, despite their very different Achilles tendon lengths, we were unable to find differences between the trabecular properties of chimpanzee and human calcanei in this specific region. There were regional differences within the calcaneus in the degree of anisotropy (DA) in both chimpanzees and humans, though the patterns were similar between the two species (higher DA inferiorly in the calcaneal tuber). Our results suggest that while trabecular bone within the calcaneus varies, it does not respond to the variation of Achilles tendon morphology across taxa in the way we hypothesized. These results imply that internal bone architecture may not be informative for reconstructing Achilles tendon anatomy in early hominins. Anat Rec, 296:1509–1517, 2013. © 2013 Wiley Periodicals, Inc.     

Anatomical study of the plantaris tendon: reliability as a tendo-osseous graft

Purpose  The purpose of this study was to investigate the insertion of the plantaris tendon in terms of shape, length, width and size, to define if there is available bony insertion for future use as reconstructive procedure in secondary tendon graft in hand surgery. Methods  In 30 limbs, the plantaris tendon was anatomically dissected to investigate its bony attachments to the calcaneus. Results  The plantaris was present in 29 of 30 dissections and regularly inserted in the calcaneus. Conclusions  The tendo-osseous plantaris graft is, according to this research, amenable to be used as a viable choice in reconstruction of secondary flexor tendon injuries related to its length shape and size and especially due to the bone stock adequate to strong phalanx fixation.     

Tensile properties of fresh human calcaneal (Achilles) tendons

The purpose of this study was to measure the tensile properties of fresh human calcaneal (Achilles) tendons. Twenty fresh cadaveric (age range = 57-93 years) bone-Achilles tendon complexes were harvested within 24 hr postmortem. The calcaneus together with 15 cm of the Achilles tendon extending proximally from the insertion on the calcaneus was clamped and biomechanically tested. Each tendon was firmly fixed in clamps in an MTS Systems Corporation MTS testing machine and tension was applied at a displacement rate of 8 cm per minute until the tendon failed. The tensile force and tensile strain (as measured using an extensometer) were recorded and plotted using onboard software. The narrow age range of our donors prevented any meaningful correlation between age and tensile properties; however, the results showed that: 1) the average ultimate tensile strength (UTS) of the human Achilles tendon was 1189 N (range = 360-1,965), 2) there was a correlation between left and right legs for UTS, 3) there was a correlation between left and right legs in regard to cross sectional area, and 4) there was no correlation between UTS and cross-sectional area.     

The functional anatomy of Kager's fat pad in relation to retrocalcaneal problems and other hindfoot disorders

Kager's fat pad is a mass of adipose tissue occupying Kager's triangle. By means of a combined magnetic resonance imaging, ultrasound, gross anatomical and histological study, we show that it has three regions that are closely related to the sides of the triangle. Thus, it has parts related to the Achilles and flexor hallucis longus (FHL) tendons and a wedge of fat adjacent to the calcaneus. The calcaneal wedge moves into the bursa during plantarflexion, as a consequence of both an upward displacement of the calcaneus relative to the wedge and a downward displacement of the wedge relative to the calcaneus. During dorsiflexion, the bursal wedge is retracted. The movements are promoted by the tapering shape of the bursal wedge and by its deep synovial infolds. Fibrous connections linking the fat to the Achilles tendon anchor and stabilize it proximally and thus contribute to the motility of its tip. We conclude that the three regions of Kager's fat pad have specialized functions: an FHL part which contributes to moving the bursal wedge during plantarflexion, an Achilles part which protects blood vessels entering this tendon, and a bursal wedge which we suggest minimizes pressure changes in the bursa. All three regions contribute to reducing the risk of tendon kinking and each may be implicated in heel pain syndromes.     

The twisted structure of the rat Achilles tendon

The rat is frequently used as a model to study the characteristics, aetiology and pathology of the Achilles tendon. However, though the structure of the human Achilles tendon has been extensively investigated, the anatomical structure of the rat Achilles tendon remains unclear, which impedes the ability to use rats to study Achilles tendinopathy. The purpose of this study was to reveal the structure of the rat Achilles tendon and to explore its similarities with the human Achilles tendon through an anatomical dissection of 80 rat Achilles tendons (40 female, 40 male). This study found that the subtendons of the rat Achilles tendon originating from the triceps surae muscle were twisted, and each subtendon also had its own torsion. The extent of these two types of torsion could be very different between rats. Alterations in this torsion may result in distinct stress fields in the Achilles tendon, which may play a critical role in the pathogenesis of Achilles tendinopathy. This study provides an important basis to support the use of rats as model animals to investigate the characteristics of the human Achilles tendon and Achilles tendinopathy.     

Blood flow in the peritendinous space of the human Achilles tendon during exercise

This study evaluated blood flow in the peritendinous space of the human Achilles tendon during rest and 40-min dynamical contraction of m. tricgif surae. In 10 healthy volunteers ¹³³Xe was injected in to the peritendinous space just ventrally to the Achilles tendon 2 and 5 cm proximal to the calcaneal insertion of the tendon, respectively. Blood flow 5 cm proximal to the Achilles tendon insertion was found to increase 4-fold from rest to exercise whereas the exercise induced increase in blood flow was less pronounced, only 2.5-fold, when measured 2 cm proximal to the Achilles tendon insertion. Lymph drainage from the area was found to be negligible both during rest and exercise. We conclude that dynamical calf muscle contractions result in increased peritendinous blood flow at the Achilles tendon in humans.     

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.     

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.     

Development and ageing of phenotypically distinct fibrocartilages associated with the rat Achilles tendon

Summary We describe by routine histology and by immunohistochemistry three phenotypically and developmentally distinct fibrocartilages associated with the Achilles tendon of the rat. All the fibrocartilages develop after birth and show significant age-related changes in the composition of their extracellular matrix. Attachment-zone fibrocartilage occurs at the insertion of the tendon on the calcaneus. It derives from the cartilage rudiment of the calcaneus and from the region where the tendon merges with the perichondrium. The extracellular matrix contain type II collagen and chondroitin sulphate. Compressive tendon fibrocartilage occurs in the deep part of the tendon where it presses against the calcaneus, and is derived by metaplasia of tendon cells. The cells label strongly for the intermediate filament vimentin, and the extracellular matrix contains chondroitin and keratan sulphates, but type II collagen only in very old animals (>2 years). Calcaneal fibrocartilage covered the posterior surface of the calcaneus where it was in contact with the Achilles tendon. It labelled intensely for type II collagen and contained chondroitin and keratan sulphates. The cells were rich in vimentin. This fibrocartilage was derived from the calcaneal perichondrium.     

新鲜闭合性跟腱断裂的微创治疗

目的　总结新鲜闭合性跟腱断裂微创治疗的方法,为临床推广应用提供依据。  方法　所有病例均采用小切口微创治疗的方法,并行跖肌腱包裹跟腱断端。  结果　出院后所有病例均获得随访,随访时间为术后3个月至2年,优良率达100%,未再次发生跟腱断裂。  结论　用微创的方法治疗新鲜闭合性跟腱断裂并行跖肌腱包裹跟腱断端,有利于术后功能恢复,手术方式易于被患者接受,值得临床推广。     

跟外侧动脉的显微外科解剖

目的探讨跟外侧动脉的起始、行程、分支和分布等情况,为临床实践提供解剖学资料。方法在12侧经股动脉灌注红色乳胶溶液的成人下肢标本上,对跟外侧动脉进行显微外科解剖,观察其出现率并测量其起始位置、起始处及穿深筋膜处的口径。以外踝尖为基点,对外踝尖上6 cm范围内每2 cm间隔内跟外侧动脉分支的蒂长和口径进行测量并作统计学分析。另取小腿动脉血管造影标本5例,进一步观察跟外侧动脉行程及其与跟腱表面皮瓣血供的关系。结果跟外侧动脉于外踝尖上4.9～9.4(6.56±1.30)]cm处源自腓动脉,起始处口径为1.0～3.3(1.78±0.60)mm,穿深筋膜处口径为0.44～2.0(0.81±0.40)mm。其全程呈"L"型,垂直段共有2～5(2.50±0.80)支分支。在外踝尖上0.00～2.00、2.01～4.00、4.01～6.00 cm间隔内,分支的蒂长和口径分别是:(0.81±0.31)、(1.68±0.55)、(1.59±0.41)cm和(0.80±0.31)、(0.80±0.11)、(0.85±0.23)mm。垂直段分支分支纵、橫穿行,纵者吻合成链状与腓肠神经及小隐静脉伴行,参与腓肠神经营养血管皮瓣供血系统的组成,橫行者越过跟腱浅面与来自胫后动脉的分支吻合,供养跟腱区皮瓣;水平段分支3～5支,分布于足外侧面后侧约1/3皮肤软组织。结论跟外侧动脉是腓动脉的直接延续,尸体标本和活体标本中跟外侧动脉出现率分别为100%和80%;跟外侧动脉既参与腓肠神经营养血管皮瓣供血系统的组成,又营养跟腱表面的皮瓣。     

An anatomic and clinical study of the adductor magnus tendon-descending genicular artery bone flap

The composite tissue flap of the descending genicular vessels with the adductor magnus tendon is a newly developed, reliable method to repair the Achilles tendon and relevant skin defects. The aim of this study was to evaluate the anatomy of the adductor magnus tendon-descending genicular artery bone flap, and the feasibility and value for the repair of the Achilles tendon and relevant skin defects. There were 34 adult specimens used for the anatomy of this flap. The descending genicular artery originates 10.5 ± 1.6 cm above the adductor tubercle, with a diameter of 1.8 ± 0.6 mm and a length of 1.2 ± 0.5 cm. Its articular branch is distributed in the adductor magnus tendon and the medial condyle of the femur. The saphenous branch has a diameter of 1.1 ± 0.3 mm and is distributed in the skin of the upper medial calf. A total of 16 cases of trauma-induced Achilles tendon damage and calcaneus and skin defects were repaired with the vascularized adductor magnus tendon bone flap, including the reconstruction of Achilles tendon insertion and repair of relevant skin defects. All of the composite tissue flaps were viable, the skin sensation of the flaps was recovered, and all patients walked with a normal gait. Our results suggested that the adductor magnus tendon-descending genicular artery bone flap is an alternative method to repair composite tissue defects of the Achilles tendon.     

Control of torque direction by spinal pathways at the cat ankle joint

To study the biomechanics of the calcaneal ten-don's complex insertion onto the calcaneus, we measured torque-time trajectories exerted by the triceps surae and tibialis anterior muscles in eight unanesthetized decerebrate cats using a multi-axis force-moment sensor placed at the ankle joint. The ankle was constrained to an angle of 110° plantarflexion. Muscles were activated using crossed-extension (XER), flexion (FWR), and caudal cutaneous sural nerve (SNR) reflexes. Torque contributions of other muscles activated by these reflexes were eliminated by denervation or tenotomy. In two animals, minia-ture pressure transducers were implanted among tendon fibers from the lateral gastrocnemius (LG) muscle that insert straight into the calcaneus or among tendon fibers from the medial gastrocnemius (MG) that cross over and insert on the lateral aspect of calcaneus. Reflexively evoked torques had the following directions: FWR, dorsiflexion and adduction; SNR, plantarflexion and abduction; and XER, plantarflexion and modest abduction or adduction. The proportion of abduction torque to plantarflexion torque was always greater for SNR than XER; this difference was about 50% of the magnitude of abduction torque generated by tetanic stimulation of the peronei. During SNR, pressures were higher in regions of the calcaneal tendon originating from MG than regions originating from LG. Similarly, pressures within the MG portion of the calcaneal tendon were higher during SNR than during XER, although these two reflexes produced matched ankle plantarflexion forces. Selective tenotomies and electromyographic recordings further demonstrated that MG generated most of the torque in response to SNR, while soleus, LG, and MG all generated torques in response to XER. Previous studies have shown that interneurons processing afferent information from both XER and SNR differentially excite the MG and LG motoneuron pools. Further, our data demonstrate that forces produced by this differential activation are preserved throughout the calcaneal tendon. We conclude that selective activation of the gastrocnemei permits the animal to take advantage of the complex mechanical insertion of MG and LG at calcaneus and, specifically, to generate different torques at the ankle joint in response to different reflex activations.     

全镜下跟腱清理与止点增强治疗跟腱部分撕裂的Haglund综合征的疗效对比

目的 比较全关节镜下跟腱清理与跟腱止点增强重建治疗跟腱部分撕裂的Haglund综合征患者的临床疗效。方法 回顾性分析2016年1月至2021年3月在青县人民医院应用全关节镜下治疗跟腱部分撕裂的Haglund综合征的24例患者资料,依据手术方式不同分为关节镜下跟腱止点清理组（A组）和关节镜下跟腱止点清理+跟腱止点增强重建组（B组）,每组各12例。术后定期随访,采用疼痛视觉模拟（VAS）评分、美国足踝外科协会（AOFAS）足踝功能评分及维多利亚体育研究所评分（VISA-A）评估治疗结果,进行观察对比。结果 患者平均随访时间（7.5±0.8）个月,末次随访均不存在后足跟肿痛、跟腱再次断裂等并发症。所有患者症状较术前均得到缓解。A组和B组的VAS评分、AOFAS评分、VISA-A评分均较术前有所改善;然而A组和B组术前及术后6个月的VAS、AOFAS、VISA-A评分对比,差异无统计学意义（P>0.05）;B组术后1、3个月的VAS、AOFAS、VISA-A评分优于A组,差异有统计学意义（P<0.05）。结论 全关节镜下跟腱止点增强重建治疗跟腱部分撕裂的Haglund综合征,较关节...     

跟腱复合组织缺损的显微外科修复

目的 :探讨跟腱复合组织缺损的显微外科治疗。方法 :应用膝降血管大收肌腱、骨、皮复合组织瓣移植一期修复跟腱伴皮肤和跟骨缺损。结果 :施术 3侧 ,取得满意效果。结论 :该术式可修复不同类型的跟腱复合组织缺损 ,并具有操作简便、易行和供区损伤小等特点。     

The co-existence of the gastrocnemius tertius and accessory soleus muscles

A bilateral gastrocnemius tertius muscle and a unilateral accessory soleus muscle were encountered during the routine educational dissection studies. The right gastrocnemius tertius muscle consisted of one belly, but the left one of two bellies. On the left side, the superficial belly of the gastrocnemius tertius muscle had its origin from an area just above the tendon of the plantaris muscle, the deep belly from the tendon of the plantaris muscle. The accessory soleus muscle originated from the posteromedial aspect of the tibia and soleal line of the tibia and inserted to the medial surface of the calcaneus. On the right side, the gastrocnemius tertius muscle had its origin from the lateral condyle of the femur, and inserted to the medial head of the gastrocnemius muscle. The co-existence of both gastrocnemius tertius and accessory soleus muscle has not, to our knowledge, been previously reported.     

The conjoint junction of the triceps surae: implications for gastrocnemius tendon lengthening

Forty embalmed cadaver lower limbs were dissected to identify the morphology of the conjoint junction of the tendons of gastrocnemius and soleus and the location of the gastrocnemius tendon relative to bony landmarks. Five patterns of conjoint junction morphology were found: transverse (25%), oblique passing distally and medially (45%), oblique passing distally and laterally (5%) and arcuate as an inverted U (17.5%) and a U-shape (7.5%). Left-right asymmetry of the junction was observed in 31.6% of 19 paired cadaver legs. On the medial side of the calf the gastrocnemius tendon could be located between 38 and 46% of the proportion of the distance between the upper border of the calcaneus and the fibular head. Corresponding values for the midline and lateral side of the calf were 45-58% and 48-51%. The location of the gastrocnemius tendon relative to bony landmarks may help to guide incision planning for open or endoscopic division of the tendon.     

Insertion of the tendon of the tibialis anterior muscle in feet with and without hallux valgus

The insertion of the tendon of the tibialis anterior muscle may be related to pathologic changes of the foot and, in particular, hallux valgus. Morphologic data should enable evaluation of such a relationship and perhaps offer a basis for improved therapy. One hundred fifty-six embalmed feet, including 27 with hallux valgus, were examined. The tendon of the tibialis anterior muscle was dissected and measurements were made, including the width of the insertion on the first metatarsal and medial cuneiform. Distal-superficial and proximal-deep slips of the tendon twisted around each other. Two specimens presented with an insertion only on the medial cuneiform; in two other cases the insertion was limited to the first metatarsal; in one case the tendon inserted into the navicular and the medial cuneiform; in all other cases, the tendon inserted into the medial cuneiform and first metatarsal. The insertion was mainly located along the plantar margin of the medial side of the foot; some of the proximal-deep fibers also passed onto the plantar surface. Fibers inserting on the first metatarsal bone can outwardly rotate the first ray, which is opposite to the inward rotation of the first ray in hallux valgus. In all feet with hallux valgus these fibers were present. Therefore, it is unlikely that this deformity develops because of a specific type of insertion of the tendon of the tibialis anterior muscle, and any therapeutic approach altering the attachment of the tibialis anterior tendon would cause no biomechanical improvement.