Adipose tissue at entheses: the innervation and cell composition of the retromalleolar fat pad associated with the rat Achilles tendon

This study set out to determine whether the fat pad at the attachment of the Achilles tendon has features enabling it to function as an immune organ and a mechanosensory device, and to be a source of pain in insertional tendon injuries. Sections for histology and immunohistochemistry were cut from the Achilles tendon enthesis organ of 1 day old, 1 month, 4 month and 24 month old rats. For fluorescence and peroxidase immunohistochemistry, cryosections were labelled with primary antibodies directed against PGP9.5, substance P, neurofilament 200, calcitonin gene related peptide, CD68, CD36, myeloid related protein 14, actin and vinculin. The fat pad contained not only adipocytes, but also fibrous tissue, mast cells, macrophages, fibroblasts and occasional fibrocartilage cells. It was richly innervated with nerve fibres, some of which were likely to be nociceptive, and others mechanoreceptive (myelinated fibres, immunoreactive for neurofilament 200). The fibres lay between individual fat cells and in association with blood vessels. In marked contrast, the enthesis itself and all other components of the enthesis organ were aneural at all ages. The presence of putative mechanoreceptive and nociceptive nerve endings between individual fat cells supports the hypothesis that the fat pad has a proprioceptive role monitoring changes in the insertional angle of the Achilles tendon and that it may be a source of pain in tendon injuries. The abundance of macrophages suggests that the adipose tissue could have a role in combating infection and/or removing debris from the retrocalcaneal bursa.     

Three-dimensional reconstructions of the Achilles tendon insertion in man

The distribution of type II collagen in sagittal sections of the Achilles tendon has been used to reconstruct the three‐dimensional (3D) shape and position of three fibrocartilages (sesamoid, periosteal and enthesis) associated with its insertion. The results showed that there is a close correspondence between the shape and position of the sesamoid and periosteal fibrocartilages – probably because of their functional interdependence. The former protects the tendon from compression during dorsiflexion of the foot, and the latter protects the superior tuberosity of the calcaneus. When the zone of calcified enthesis fibrocartilage and the subchondral bone are mapped in 3D, the reconstructions show that there is a complex pattern of interlocking between pieces of calcified fibrocartilage and bone at the insertion site. We suggest that this is of fundamental importance in anchoring the tendon to the bone, because the manner in which a tendon insertion develops makes it unlikely that many collagen fibres pass across the tissue boundary from tendon to bone. When force is transmitted to the bone from a loaded tendon, it is directed towards the plantar fascia by a series of highly orientated trabeculae that are clearly visible in 3D in thick resin sections.     

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.     

个性化足跟痛缓冲鞋垫的生物力学研究

目的研究带有不同结构后跟垫的个性化鞋垫对足跟痛患者足部应力集中的作用效果。方法结合统计学和有限元分析方法,建立足跟痛患者足部及个性化鞋垫有限元模型,仿真模拟不同鞋垫对足跟痛患者足部软组织内外及足底筋膜应力的作用效果。结果足部软组织内部所受应力高于足底表面,足底筋膜应力在第3根筋膜上的应力最高。裸足站立时足跟区软组织内部应力峰值是表面峰值的1.34倍,足底第3根筋膜的应力为1.50 MPa。通过正交试验得到的优化鞋垫模型能够降低足跟区软组织内部应力峰值51.0%,同时缓解足底第3根筋膜应力11.3%。结论带有竖轴椭圆形、蜂窝状孔槽结构后跟垫的个性化缓冲鞋垫方案较优,后跟垫能辅助跟骨脂肪垫吸收或缓冲震荡,较好地减轻足底应力分布集中的同时具有缓解足底筋膜张力的作用。结果有助于认识足跟痛足部的应力分布情况,对研究足跟痛的病理和治疗具有重要的意义。     

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.     

Plantar fascia anatomy and its relationship with Achilles tendon and paratenon

Although the plantar fascia (PF) has been studied quite well from a biomechanical viewpoint, its microscopic properties have been overlooked: nothing is known about its content of elastic fibers, the features of the extracellular matrix or the extent of innervation. From a functional and clinical standpoint, the PF is often correlated with the triceps surae muscle, but the anatomical grounds for this link are not clear. The aim of this work was to focus on the PF macroscopic and microscopic properties and study how Achilles tendon diseases might affect it. Twelve feet from unembalmed human cadavers were dissected to isolate the PF. Specimens from each PF were tested with various histological and immunohistochemical stains. In a second stage, 52 magnetic resonance images (MRI) obtained from patients complaining of aspecific ankle or foot pain were analyzed, dividing the cases into two groups based on the presence or absence of signs of degeneration and/or inflammation of the Achilles tendon. The thickness of PF and paratenon was assessed in the two groups and statistical analyses were conducted. The PF is a tissue firmly joined to plantar muscles and skin. Analyzing its possible connections to the sural structures showed that this fascia is more closely connected to the paratenon of Achilles tendon than to the Achilles tendon, through the periosteum of the heel. The PF extended medially and laterally, continuing into the deep fasciae enveloping the abductor hallucis and abductor digiti minimi muscles, respectively. The PF was rich in hyaluronan, probably produced by fibroblastic‐like cells described as ‘fasciacytes’. Nerve endings and Pacini and Ruffini corpuscles were present, particularly in the medial and lateral portions, and on the surface of the muscles, suggesting a role for the PF in the proprioception of foot. In the radiological study, 27 of the 52 MRI showed signs of Achilles tendon inflammation and/or degeneration, and the PF was 3.43 ± 0.48 mm thick (99%CI and SD = 0.95), as opposed to 2.09 ± 0.24 mm (99%CI, SD = 0.47) in the patients in which the MRI revealed no Achilles tendon diseases; this difference in thickness of 1.29 ± 0.57 mm (99%CI) was statistically significant (P < 0.001). In the group of 27/52 patients with tendinopathies, the PF was more than 4.5 mm thick in 5, i.e. they exceeded the threshold for a diagnosis of plantar fasciitis. None of the other 25/52 paitents had a PF more than 4 mm thick. There was a statistically significant correlation between the thicknesses of the PF and the paratenon. These findings suggest that the plantar fascia has a role not only in supporting the longitudinal arch of the foot, but also in its proprioception and peripheral motor coordination. Its relationship with the paratenon of the Achilles tendon is consistent with the idea of triceps surae structures being involved in the PF pathology, so their rehabilitation can be considered appropriate. Finally, the high concentration of hyaluronan in the PF points to the feasibility of using hyaluronan injections in the fascia to treat plantar fasciitis.     

Normal anatomy of the heel entheses: anatomical and ultrasonographic study of their blood supply

The purpose of this study was first to determine the normal blood supply of the heel entheses with cadaver injection, and second, to identify by means of ultrasound (US) this blood supply in healthy volunteers before and after the intravenous injection of a US contrast agent (SonoVue). Twenty cadaver lower limbs were cut into sagittal, coronal, or axial sections after the injection of a red-colored gelatin solution. Ten anatomical samples were selected for histology. Then 10 healthy volunteers were enrolled in a contrast-enhanced ultrasonography study (CUS). Calcaneal tendon and plantar aponeurosis entheses were studied first without any contrast-agent (B-mode, power Doppler). A single dose (2.4 ml) of the contrast agent was then administered for studying each enthesis of the right foot. The operators had to look for blood flow within the entheses and in the adjacent soft tissues. Anastomotic transverse branches were seen macroscopically at the back of the calcaneal tendon, giving some capillaries penetrating the enthesis. None of these vessels could be seen with CUS. In contrast, a high-density vascular network could be detected in Kagers triangle with CUS. No blood vessel could be seen within the plantar aponeurosis enthesis, either macroscopically or microscopically. No evidence of entheseal vascularization was found with any contrast-enhanced imaging technique. Inferior branches of the lateral plantar artery were seen on coronal and sagittal sections of the hindfoot, and could be detected with CUS. These arterioles were running toward the anterior aspect of the calcaneal tuberosity, near the plantar aponeurosis insertion. In conclusion, no vascularization was detected with CUS at the cortical bone insertion of normal heel entheses. However, some vascularization could be seen in the immediate vicinity of heel entheses. The latter feature has to be kept in mind, as it may represent a pitfall for the diagnosis of early inflammatory changes in patients, especially those with seronegative spondylarthropathies.     

Clinical anatomy of the calcaneal tuberosity.

The aim of the study was a qualitative anatomical analysis of the macroscopic features of the surface of the calcaneal tuberosity, of the architecture of its cancellous bone and histological structure of the whole region. Dry human bones and pathological dissection material 24-36 h post mortem were used in the study. On the tuberosity, the variability of its surface relief and the two borders between the superior, middle and inferior facets were studied. More frequent medial declination of the inferior line, corresponding to the distal circumference of the Achilles tendon attachment, was found. Two systems of expressive condensation of cancellous bone just below the surface of the calcaneal tuberosity were described. In the histological part of the study, the distribution and different thickness of the fibrous cartilage layer covering the attachment region of Achilles tendon, the bottom of retro-calcaneal bursa and the whole surface of the calcaneal tuberosity were described. The functional and clinical relevance of results obtained are evaluated from the point of view of disciplines dealing with the pathology and surgery of the heel region. The relationships of official anatomical terms and a wide spectrum of clinical synonyms designating this region are discussed.     

足底腱膜的解剖

目的观察足底腱膜的形态结构,为临床应用提供相关的解剖学资料。方法解剖50只10%甲醛固定的足,观察足底腱膜浅层的形态结构;测量足底腱膜中间部(跖腱膜)止于跖骨头处内、外侧纤维束的厚度与长度;跖腱膜中间部的厚度。结果足底腱膜浅层的纤维结构主要参与前外侧部足底脂肪垫的构成,并形成与足底皮纹相似的螺旋纤维板状结构,足跟部足底腱膜浅层的纤维结构较为稀疏。中间部的厚度为(2.168±0.1139)mm;跖腱膜于第1跖骨头处内、外侧纤维束的厚度分别为(1.33±0.08)mm、(1.46±0.07)mm,明显大于止于2~5跖骨头处的内、外侧纤维厚度,P0.05;第5跖骨头处的内、外侧纤维厚度分别为(0.29±0.02)mm、(0.37±0.04)mm,明显小于1~4跖骨头处的内、外侧纤维厚度,P0.05。结论足底腱膜浅层主要参与足前外侧脂肪垫的构成,足底腱膜深层对维持足部纵弓的稳定起着非常重要的作用,在足部受力时有效地避免足前部趾足底总神经、趾足底总血管受压。     

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。     

跟外侧动脉穿支皮瓣的应用解剖

目的　探讨跟腱区及跟部皮肤软组织的血供解剖学,为跟外侧动脉穿支皮瓣的临床应用提供解剖学基础。 方法　16侧经红色乳胶灌注的成人下肢标本,解剖观察跟外侧动脉“垂直段”及其穿支血管的位置、口径、数目及分布规律。 结果　位于小腿后骨筋膜鞘深部的腓动脉于外踝尖上(6.6±1.1) cm ( 5.5~9.4 cm) 发出腓动脉前穿支和跟外侧动脉,跟外侧动脉下行穿出分隔小腿后骨筋膜鞘浅、深部之小腿后筋膜隔到达外踝后间隙,于腓骨肌腱与跟腱之间移行,继续绕外踝向前下方分布。小腿下段腓动脉、跟外侧动脉穿支数为(3.6±0.7)支,口径为（0.9±0.29） mm,营养跟腱区及跟部皮肤软组织。 结论　研究结果显示跟腱区及跟部皮肤软组织的血供主要来源于腓动脉、跟外侧动脉,为跟外侧动脉的命名、临床应用以及小腿中下段皮瓣的设计和跟部手术提供解剖学基础。     

The paratendineous tissues: an anatomical study of their role in the pathogenesis of tendinopathy

The aim of this paper was to examine the macroscopic and microscopic characteristics of the paratendineous tissues (paratenon, epitenon and endotenon) of the calcaneal tendon to better understand their role in the pathogenesis of “tendinopathy”. Ten non-embalmed legs from cadavers were used. Histological and immunohistochemical studies were done at the middle third of the tendon. Magnetic resonance images of the hind foot were made in 60 living subjects to analyze the morphological alterations of tendon and paratenon. The paratenon is a thick fibrous layer with few elastic fibers, continuous with the crural fascia, well vascularized and innervated. It forms a sheath around the tendon similar to a synovial layer, but less organized. Indeed, it has no complete epithelium, but only some cells producing hyaluronan, called fasciacytes. Crural fascia and paratenon can be clearly observed by MRI, appearing as homogeneous, low signal intensity bands, sharply defined in the context of subcutaneous tissue in T1-weighted sequences. The mean thickness of the crural fascia was 1.11 mm in healthy subjects and 1.30 mm in patients (p < 0.005). The mean value of paratenon thickness in patients was 1.34 mm, 0.85 in healthy (p < 0.0001). The paratenon is more highly vascularized and innervated than the tendon, supporting the hypothesis that it is the origin of pain in tendinopathy. The imaging study suggests that, an increase in the thickness of the paratenon more than 1.35 mm is predictive of paratendinopathy, even before tendon damage.     

基于有限元法对足跟痛在推离期的生物力学研究

基于有限元法对推离期下足跟痛的发病和康复机理进行研究。采集一位足跟痛患者的CT和MRI图像用于三维重建,利用Geomagic软件对得到的模型表面优化,再通过Hypermesh软件对模型进行有限元前处理,最后将得到的下肢有限元模型导入到Abaqus中分析计算,与足底压力板测试结果对比验证模型的有效性,并根据计算结果分析小腿三头肌力的变化对足踝步态推离期生物力学行为特性的影响。结果表明,小腿三头肌肌肉力从550 N增大到1 100 N的过程中,第一趾骨区的峰值压力增大了32.8%,跖骨区的峰值压力增大了14.3%;第一根足底筋膜的应力高达4.69 MPa;跟腱与跟骨连接处和跟骨结节部位的应力峰值分别为28.36和32.79 MPa。由此可见,小腿三头肌挛缩和推离期的绞盘效应会导致足底筋膜过度拉伸,引起跟骨结节处的应力水平提高,使得足部生物力学环境发生变化,从而诱发足底筋膜炎,导致足跟痛。缓解小腿三头肌挛缩、减小肌肉力、避免足底筋膜过度拉伸及降低附着点处的应力水平以恢复足部正常生物力学环境,是治疗足跟痛的主要康复机理。     

The lateral calcaneal artery: Anatomic basis for planning safe surgical approaches

The proximity of the lateral calcaneal artery (LCA) to surgical incisions applied to the lateral hindfoot makes it vulnerable to iatrogenic injury and subsequent postoperative skin necrosis. This study aimed to investigate the course of the LCA and to define anatomical points that can be used by surgeons during lateral approaches to the calcaneus. Thirteen leg‐ankle‐foot specimens were dissected and the superficial course of the LCA was outlined by three anatomic points: (a) tip of lateral malleolus, (b) the point where it pierces the deep fascia, and (c) the point where it crosses the line connecting the lateral malleoluswith the insertion of Achilles tendon. Fifteen healthy volunteers were investigated by color Doppler ultrasound where the diameter and depth of LCA were measured. The LCA pierced the deep fascia at a maximum height of 4.5 cm (mean 3.78) above the midpoint of a line extending from the lateral malleolus to the insertion of Achilles tendon. It crossed the previous line at a maximum distance of 3 cm (mean 2.6) posterior to lateral malleolus. At this point, its mean diameter was 1.75 mm on the right and 1.73 mm on the left sides, while its mean depth was 7.73 mm on the right and 8.0 mm on the left sides. A dangerous triangle that contained the superficial course of the artery was mapped out in the lower lateral part of the leg. This triangle should be considered during surgical approaches applied to the lateral hindfoot to avoid damage of the LCA. Clin. Anat. 22:834–839, 2009. © 2009 Wiley‐Liss, Inc.     

The plantaris tendon and a potential role in mid-portion Achilles tendinopathy: an observational anatomical study

The source of pain and the background to the pain mechanisms associated with mid-portion Achilles tendinopathy have not yet been clarified. Intratendinous degenerative changes are most often addressed when present. However, it is questionable if degeneration of the tendon itself is the main cause of pain. Pain is often most prominent on the medial side, 2-7cm from the insertion onto the calcaneus. The medial location of the pain has been explained to be caused by enhanced stress on the calcaneal tendon due to hyperpronation. However, on this medial side the plantaris tendon is also located. It has been postulated that the plantaris tendon might play a role in these medially located symptoms. To our knowledge, the exact anatomy and relationship between the plantaris- and calcaneal tendon at the level of complaints have not been anatomically assessed. This was the purpose of our study. One-hundred and seven lower extremities were dissected. After opening the superficial fascia and paratendon, the plantaris tendon was bluntly released from the calcaneal tendon moving distally. The incidence of the plantaris tendon, its course, site of insertion and possible connections were documented. When with manual force the plantaris tendon could not be released, it was defined as a 'connection' with the calcaneal tendon. In all specimens a plantaris tendon was identified. Nine different sites of insertion were found, mostly medial and fan-shaped onto the calcaneus. In 11 specimens (10%) firm connections were found at the level of the calcaneal tendon mid-portion. Clinical and histological studies are needed to confirm the role of the plantaris tendon in mid-portion Achilles tendinopathy.     

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.     

Three‐dimensional imaging of the fibrous microstructure of Achilles tendon entheses in Mus musculus

The whole‐organ, three‐dimensional microstructure of murine Achilles tendon entheses was visualized with micro‐computed tomography (microCT). Contrast‐enhancement was achieved either by staining with phosphotungstic acid (PTA) or by a combination of cell‐maceration, demineralization and critical‐point drying with low tube voltages and propagation‐based phase‐contrast (fibrous structure scan). By PTA‐staining, X‐ray absorption of the enthesial soft tissues became sufficiently high to segment the tendon and measure cross‐sectional areas along its course. With the fibrous structure scans, three‐dimensional visualizations of the collagen fiber networks of complete entheses were obtained. The characteristic tissues of entheses were identified in the volume data. The tendon proper was marked as a segment manually. The fibers within the tendon were marked by thresholding. Tendon and fiber cross‐sectional areas were measured. The measurements were compared between individuals and protocols for contrast‐enhancement, using a spatial reference system within the three‐dimensional enthesis. The usefulness of the method for investigations of the fibrous structure of collagenous tissues is demonstrated.     

The frequency of Achilles and plantar calcaneal spurs in gout patients

Background/aim Gout may cause various radiographic abnormalities such as cartilage loss, spurs, sclerosis, and periostal new bone formation. The purpose of this study was to investigate the frequency of Achilles and plantar spurs and related factors in gout patients.Matherial and methodsWe performed a retrospective review of gout patients, treated at Hacettepe University hospitals between 2014 and 2019. We identified patients from the hospital records using the ICD-10 code (M10). Demographic and clinical features, comorbidities, and foot radiographies were collected. The radiographies were evaluated by a rheumatologist (U.K.) who was experienced in musculoskeletal radiography. Factors predicting the spurs were analyzed by logistic regression analysis.Results181 patients who had lateral foot radiograph were included in this study. Eighty-one (44.7%) patients had score ≥ 2 Achilles spur, 81 (44.7%) patients had score ≥ 2 plantar spur, and 22 (12.1%) patients had no spur. Age, disease duration, duration between the gout diagnosis and appearing spur, the presence of metabolic comorbidities and hypertension were higher in both Achilles and plantar spurs than no spur group. Forty (22.1%) patients had score ≥ 2 both Achilles and plantar spur. In this group, the mean age was older and the proportion of metabolic comorbidities was higher than the groups of Achilles and plantar spur with a score 0 or 1. Predictor of the development of large or moderate-severe calcaneal spur was the existence of metabolic comorbidity [OR (95% CI): 3.49 (1.11–11.0) and p = 0.033].ConclusionThe presence of metabolic comorbidities increases the frequency of calcaneal spurs in gout patients. This condition can be explained by the impaired microvascular structure and increased hypoxia resulting in calcification on the tendon and ligament insertion sites.     

Geometric and elastic properties of in vivo human Achilles tendon in young adults

The purpose of this study was to clarify whether the major determinant of the extendibility of the Achilles tendon in young adults was the geometric properties of the tendon. The subjects were 38 healthy young adults (26 male, 12 female; 26 +/- 5 years). The subjects developed maximum voluntary isometric plantar flexion (MVIP) torque while the displacement of the distal myotendinous junction of the medial gastrocnemius and ankle joint rotation was determined using a B-mode ultrasonograph and a goniometer, respectively. The tendon force (F) was calculated from MVIP torque and the moment arm of Achilles tendon. The elongation of the Achilles tendon (delta X) was obtained from the tendon displacements and ankle joint rotation. Achilles tendon stiffness (k) was calculated by dividing F by delta X. The specific stiffness of the Achilles tendon (k(s)) was obtained from k normalized to the Achilles tendon length at rest. The cross-sectional area of the Achilles tendon (CSA) was measured at 5, 10, and 15% of the lower leg length proximal to the insertion of the Achilles tendon using a B-mode ultrasonography. The results showed that more distal portion of the Achilles tendon had a larger CSA, and that there was a strong correlation between the average and minimum Achilles tendon CSA. delta X was 9.9 +/- 2.5 mm. k and k(s) were 330 +/- 77 N/mm and 63 +/- 20 kN, respectively. No significant correlation was seen between CSA and k(s) (r = 0.15, p > 0.05). It was suggested that a stiffer Achilles tendon did not necessarily have a thicker shape, which might indicate that the major determinant of the extendibility of the Achilles tendon was not its geometric properties in young adults.     

基于生物力学有限元法的足跟痛发生与康复机制

目的 研究足跟痛病症的发生与康复机制,为临床上足跟痛治疗方法的有效性提供理论依据。方法 对足跟痛患者足膝部CT、MRI影像数据进行三维重建,建立患者足膝部的骨骼-肌肉复合有限元模型。基于所建模型采用有限元方法,仿真模拟小腿肌肉挛缩对足踝部生物力学性能的影响。结果 在小腿肌肉提升力的作用下,足底压力从足跟区向足掌区转移,且不同肌肉作用力组合方案对压力分布不产生明显差异。足底筋膜张力升高,跟骨表面产生应力集中。在240 N作用力下,跟腱附着位置和跟骨结节处产生应力峰值,分别高达10.82、11.2 MPa。结论 小腿部肌肉和跟腱中产生应力集中,会导致足踝部生物力学特性发生变化,引发足跟部疼痛。释放集中应力恢复踝关节中各骨骼和关节的位置,从而改善整体生物力学环境的方法是治疗足跟痛的康复机制。