Computer-assisted design of the sagittal shapes of a ligament-compatible total ankle replacement

The poor results of total ankle replacement have been attributed to the inability of designers to restore adequately the critical mutual function of the ligaments and the articular surfaces. The purpose of this study was to design sagittal shapes of the articular surfaces for a new ankle prosthesis to be compatible with the geometry of the reticular surfaces for a new ankle prosthesis to be compatible with the geometry of the retained ligamentous structures. Several ligament-compatible pairs of articular surfaces were tested using a computerised version of a four-bar linkage model. The kinematics of the ankle when replaced by non-conforming two-component and by fully conforming three-component designs with either flat, concave or convex tibial surfaces were assessed by the model. A ligament-compatible convex-tibia fully-congruent three-component prosthesis showed the best features. The three-component prosthesis allows complete congruence over the entire range of flexion. A convex shape for the tibial are was preferred because of the better degree of entrapment of the meniscal bearing. A 5 cm convex-tibia arc radius gave 2 mm entrapment together with 9.8 mm of tibial bone cut. Ligament elongation imposed by full congruence of the articular surfaces was less than 0.03% of the original length. The original patterns of joint kinematics and ligament tensioning are closely restored in the joint replaced by the proposed prosthesis.     

Dynamic simulation of the natural and replaced human ankle joint

Disappointing results for total ankle replacement have been explained by poor knowledge of the mechanics of the intact and replaced joints. Dynamic simulation tools have the capacity to simulate dynamic conditions that occur in human joints. The Working Model 2D tool was used to simulate the mechanics of the intact and replaced ankle joints, based on previously validated mathematical models. Elementary objects were used to model ligaments, articular surfaces, retinacula and muscle-tendon units. The performance of several pairs of prosthetic articular surfaces was also analysed. According to the results of these simulations, rolling as well as sliding motion occurs in the natural ankle, governed by a ligamentous linkage. Elongation of the tibiocalcaneal and calcaneofibular ligaments was found to be 1.5% and 4.8%, respectively. A 13% change in lever arm length occurred for both the tibialis anterior and gastrocnemius muscles during ankle flexion. Unlike the currently available three-component designs, the newly proposed convex-tibial ligament-compatible prosthesis was found to be able to restore the original mobility and physiological function of the ligaments. This prosthesis combines freedom from restraint with congruity of the components throughout the range of flexion.     

不同手术方式治疗踝关节韧带复合体损伤的生物力学评价

目的　研究不同手术方式治疗踝关节3个韧带复合体同时损伤的生物力学特征。 方法　选用6例成年新鲜正常踝关节,建立3组模型：A组：模拟内、外侧韧带损伤后予以形态和张力完全修复,下胫腓联合不固定。B组：模拟内、外侧韧带损伤后予以形态和张力完全修复,固定下胫腓联合。C组：模拟踝关节外侧韧带损伤后予以形态和张力完全修复,固定下胫腓联合,内侧韧带损伤不修复。 6例踝关节按A 、B、C顺序分别入组,分别在背伸10°等5种状态下加载压力,记录和比较各组标本的峰值压力。 结果　各状态下应力比较：B组＜C组＜A组;B组与A组比较均有统计学差异（P＜0.05）;B组与C组比较在背伸、外翻位有统计学差异（P＜0.05）,在其他位置无统计学差异。 结论　当踝关节3个韧带复合体同时损伤时,内、外侧韧带同时完好（或修复）,并且固定下胫腓联合的手术方式能使踝关节应力减至最低。     

踝关节外侧韧带和距下关节韧带修复重建的应用解剖

目的 :为踝关节外侧韧带和距下关节韧带损伤修复重建提供解剖学基础。方法 :在 3 2侧经防腐固定、8侧冷藏新鲜标本上解剖观测踝关节外侧韧带和距下关节韧带及小趾趾长伸肌腱、第 3腓骨肌腱、腓骨短肌腱、伸肌下支持带 ,在新鲜标本上摹拟修复术。结果 :小趾趾长伸肌腱、第 3腓骨肌腱、腓骨短肌腱、伸肌下支持带解剖位置恒定 ,与踝关节外侧韧带和距下关节韧带相毗邻 ,具有一定的长、宽、厚度 ,可形成移植供体。结论 :①陈旧性踝关节外侧韧带和距下关节韧带的损伤 ,原位修复较难 ,用肌腱转位修复是一种可行的方法 ;②可用腓骨短肌腱修复距腓前和跟腓韧带损伤 ,小趾趾长伸肌腱和第 3腓骨肌腱转位修复距下关节韧带 ,伸肌下支持带可用作加强缝合 ,术式经标本摹拟具有可行性。     

旋后外旋型踝关节损伤有限元模型的建立与力学分析

目的模拟旋后外旋型踝关节损伤,建立踝关节三维有限元模型。方法基于正常人体踝关节CT图像,建立包含韧带的踝关节三维数值模型;采用有限元方法对Lauge-Hanson分型4种不同程度的旋后外旋型踝关节损伤进行分析,得到踝关节应力及胫距关节面的压力分布。结果施加旋后外旋载荷时,应力最大值位于胫腓前韧带胫骨附着点;断裂胫腓前韧带后,则位于骨间膜;继续断裂骨间膜后,应力较大值位于踝关节后韧带;再断裂胫腓后韧带后,应力较大值位于三角韧带。压力较大值则位于腓骨远端、胫距下关节面后部。结论建立的踝足部三维数值模型可用于旋后外旋型踝关节损伤的的力学机理分析,计算出的踝关节应力及胫距关节面的压力分布符合临床中Lauge-Hanson分型的描述。     

外踝韧带张力测定与踝关节不稳定性实验

本实验应用改良扣带式张力传感器测定了32侧完整成人下肢踝关节骨—韧带标本,并模拟腓骨部分切除和外踝韧带断裂后,进行了踝关节不稳定性试验,发现这些结构的损伤可造成相应的踝关节不稳定,腓骨切除后胫腓前后韧带张力增加,而距腓前后韧带与跟腓韧带张力减小(P<0.05),并出现踝关节不稳,内旋、内收和前抽屉运动分别增加4.3°,4.6°和2.3mm(P<0.05)。     

MRI探究交叉韧带松紧度与髌股关节面损伤相关性的临床应用

目的　探究交叉韧带松紧度与髌股关节面损伤程度的相关性,分析个体交叉韧带长度的解剖差异对髌股关节面损伤的影响,为预防和诊治髌股关节面疾病提供新的依据。 方法　随机收集南方医科大学珠江医院2016年10月至2017年12月110例膝关节MRI资料,磁共振矢状位上测量前、后交叉韧带长度A与B,测量前、后交叉韧带起止点距离La与Lb,计算交叉韧带松紧度M值;根据矢状位与冠状位上评判髌股关节面损伤程度0、I、II、III与IV级并分别设5个组。通过SPSS20.0统计学软件,将所得数据进行One-Way ANOVA方差分析与Spearman相关性分析,探究交叉韧带松紧度与髌股关节面损伤程度的相关性。 结果　One-Way ANOVA方差分析得出各组M值两两之间均存在显著性差异（P<0.05）,Spearman相关性分析显示M值与髌股关节损伤程度间存在正相关性。 结论　交叉韧带松紧度与髌股关节面损伤存在相关性,随着M值越大,髌股关节面损伤程度越严重。     

颞下颌关节被动运动时的轴心

采用5具尸体头颅,取其半侧,切除皮肤和肌肉,先保留韧带,再除去韧带,分别拍摄从咬(牙合)位至大张口位共8个位置的X光片。以探讨颢下颌关节在被动运动时的轴心位置。在除去韧带的情况下,髁突绕本身的轴作中心定轴转动,该中心位于髁嵴下方6毫米处,运动发生在髁突与关节盘之间。在保留韧带的情况下,下颌张口运动也是定轴转动,轴心位于髁嵴下方约12毫米处的Q点,髁突绕偏心的Q点转动,同时带动关节盘一起向前下滑动。     

踝关节内侧韧带的应用解剖学研究

目的：探讨踝关节内侧韧带的组成及其各部的附着、走行及毗邻关系。方法：取30例40％甲醛溶液防腐保存的正常成人尸体标本及4侧临床截肢的新鲜成人正常踝关节标本。仔细解剖出踝关节内侧韧带各组成部分的起止点及毗邻关系,然后测量各部的长、宽及厚的数值。结果：踝关节内侧副韧带由深浅两层组成。浅层包括胫舟韧带、胫韧带及胫跟韧带,其中胫韧带和胫跟韧带是恒定的;深层由胫距前、后韧带组成,其中胫距后韧带是恒定的。测量结果显示：胫舟韧带最长,（29．2±3．54）mm;胫距后韧带最宽、最厚,分别是（12．5±3．51）mm和（10．1±2．34）mm。结论：本研究为踝关节内侧韧带损伤的修复重建提供了重要的解剖学基础。     

正常踝关节内、外侧韧带的解剖及其影像学表现

目的:探讨正常踝关节内、外侧韧带的解剖形态及其MRI和CT表现。方法:6例正常人踝关节新鲜标本MRI扫描,解剖显示内、外侧韧带后,CT断层扫描与MRI对照观察踝关节内、外侧韧带的影像学表现;在30例正常志愿者踝关节的MRI上测量内、外韧带的宽度及厚度。结果:MRI横断面及冠状面可充分显示踝关节内、外侧韧带及其周围组织的解剖结构;踝关节内、外侧韧带在冠状面及横断面上所测的宽、厚度,男女间存在一定的差异。结论:MRI能清晰地显示踝关节的解剖结构,所测量的正常踝关节内、外侧韧带的宽、厚度数据,为临床诊断踝关节内、外侧韧带的病变提供了形态学依据。     

A novel 9-region systematic assessment tool for separated ossicle at the fibular tip effects on lateral ankle ligament complex integrity: a cadaveric study

Purpose

Fibular tip ossicle separation can cause ligament injury leading to chronic lateral ankle instability. A cadaveric study was conducted to preliminarily assess the effects of fibular tip separated ossicle location and size on lateral ankle ligament complex integrity.

Methods

X-ray examinations and dissection of the anterior talofibular and calcaneofibular ligaments were conducted in ten radiographically confirmed normal below-knee cadaveric specimens extracted from donated fresh cadavers. Ossicle and bone fragment location and size were recorded, and distal fibula, articular surface, and adjacent ligament effects were determined by a novel 9-region matrix.

Results

Ligament risk varied by region. Anterior talofibular ligament width, perpendicular distance to fibular tip, sagittal width of distal fibula, and coronal width of distal fibula at attachment were 7.45 ± 0.22, 11.75 ± 1.03, 20.56 ± 1.54, and 8.68 ± 0.12 mm, respectively. Sagittal distal fibula and calcaneofibular ligament maximum widths at fibular attachment articular surfaces were 16.81 ± 0.96 and 3.50 ± 0.44 mm, respectively. Anterior talofibular to calcaneofibular ligament distance was 2.35 ± 0.14 mm. Separated ossicles >10 mm in regions 1–3 affected anterior talofibular ligaments, calcaneofibular ligaments, and fibular ankle joints; while those in regions 4, 8, and 7 or 9 affected anterior talofibular or calcaneofibular ligaments or were without impact.

Conclusions

At the fibular tip, separated ossicles sized >10 mm impact collateral ligaments and articular surfaces, while those 5–10 and <5 mm impact anterior talofibular or calcaneofibular ligaments, potentially impairing the lateral ankle ligament complex. Thus, systematic matric-based assessment of ossicle size and location can potentially improve and standardize ankle fracture care.     

Biomechanically important articular surfaces in the talocrural joint.

The authors investigated the influence of relations between the utile areas of the articular faces in ankle joint in medial twisting of the foot. For their investigation they used the material from the Institute of Anatomy "Drago Perovi?", Institute of Pathology and Institute for Forensic medicine of the Medical Faculty of Zagreb. Investigations were performed in articular faces of the tibia, fibula and talus on the left and right legs of the adults. Mutual comparing of the joint faces, their areas and altitudes, angles between the medial malleolus and tibia, and the altitudes of the medial and lateral malleolus has shown great individual differences. According to these results the authors concluded that the disproportion of the articular bodies caused habitual medial twisting of the foot. The importance and the role of ligaments, muscles and joint capsule were not the object of this investigation. The obtained results are a contribution to the functional anatomy of the ankle joint, and to the clinical pathology of this region.     

外侧楔形鞋垫对足踝生物力学影响的有限元分析

目的 探究外侧楔形鞋垫对足踝内部组织(包括足骨、关节和韧带)的生物力学影响。 方法 建立并验证足踝-鞋垫-地面三维有限元模型,探究步态 3 个关键瞬间赤足模型和鞋垫干预模型的足底压力分布、关节接触压力、跖骨及主要韧带的应力。 结果 5°外侧楔形鞋垫模型足底峰值压力比赤足模型减小 65. 8% 。 鞋垫干预使楔舟关节处峰值接触压力减小;距下关节处峰值接触压力和第 4、5 跖骨处峰值应力增大。 结论 本研究量化评估了外侧楔形鞋垫对足踝各部分的生物力学影响,提出了可适当减小外侧楔形鞋垫第 4、5 跖骨处倾斜角度的设计建议。     

An optimization-based simultaneous approach to the determination of muscular, ligamentous, and joint contact forces provides insight into musculoligamentous interaction

Typical inverse dynamics approaches to the calculation of muscle, ligament, and joint contact forces are based on a step-wise solution of the equations of motion. This approach is therefore limited in its ability to provide insight as to the muscular, ligamentous, and articular interactions that create joint stability. In this study, a new musculoskeletal model of the lower limb is described, in which the equations of motion describing the force and moment equilibrium at the joints of the lower limb are solved simultaneously using optimization techniques. The new model was employed to analyze vertical jumping using a variety of different optimization cost functions and the results were compared to more traditional approaches. The new model was able to find a solution with lower muscular force upper bounds due to the ability of the ligaments to contribute to moment equilibrium at the ankle and knee joints. Equally, the new model produced lower joint contact forces than traditional approaches for cases which also included a consideration as to ligament or joint contact forces within the cost function. This study demonstrates the possibility of solving the inverse dynamic equations of motion simultaneously using contemporary technology, and further suggests that this might be important due to the complementary function of the muscles and ligaments in creating joint stability.     

Dorsal column projection of fibres from the cat knee joint

1. Stimulation of the cervical dorsal columns excited an average of nine knee joint fibres in the cat posterior articular nerve, eleven fibres in the cat medial articular nerve and thirteen fibres in the monkey posterior articular nerve.2. Joint fibres projecting to cervical levels were shown to be rapidly adapting by recording with micro-electrodes from single fibres in intact cat posterior articular nerves. The numerous slowly adapting fibres could not be antidromically excited from the cervical dorsal columns.3. Several control experiments suggested that the antidromic stimulation method accurately defined the dorsal column projection of joint fibres.     

Intra-articular calcium phosphate cement: Its fate and impact on joint tissues in a rabbit model

Clinical application of injectable ceramic cement in comminuted fractures revealed penetration of the viscous paste into the joint space. Not much is known on the fate of this cement and its influence on articular tissues. The purpose of this experimental study was to assess these unknown alterations of joint tissues after intra-articular injection of cement in a rabbit knee. Observation periods were from 1 week up to 24 months, with three rabbits per group. Norian SRS cement was injected into one knee joint, the contralateral side receiving the same volume of Ringers' solution. Light microscopic evaluation of histologic sections was performed, investigating the appearance of the cement, inflammatory reactions, and degenerative changes of the articular surface. No signs of pronounced acute or chronic inflammation were visible. The injected cement was mainly found as a single particle, anterior to the cruciate ligaments. It became surrounded by synovial tissues within 4 weeks and showed signs of superficial resorption. In some specimens, bone formation was seen around the cement. Degeneration of the articular surface showed no differences between experimental and control side, and no changes over time became apparent. No major degenerative changes were induced by the injected cement. The prolonged presence of cement still seems to make it advisable to remove radiologically visible amounts from the joint space.     

Horizontally oriented clusters of multiple chondrons in the superficial zone of ankle, but not knee articular cartilage

Osteoarthritis is a progressive disease that is initiated at the surface of articular cartilage and proceeds to destroy the entire depth of the cartilage. The prevalence of osteoarthritis varies in different joints; e.g., the ankle joint has a very low prevalence of the disease compared to the knee joint. To better understand any inherent differences between the articular cartilage of the ankle and that of the knee that would account for the difference in occurrence of osteoarthritis, studies were undertaken to examine differences between the superficial zones in these two joint cartilages obtained from human donors. Chondrocytes in the superficial zones of the normal ankle (talocrural) and the normal knee (tibiofemoral) joints were identified with a monoclonal antibody specific for the superficial zone protein (SZP). When the chondrocytes from both joints were compared in serial horizontal sections, the chondrocytes in the superficial zone of the knee cartilage were seen either as isolated single cells or as doublets. However, the chondrocytes within the superficial zone of normal ankle cartilage were arranged in planar clusters containing multiple chondrons composed of 2-13 cells. There were no detectable differences in the chondrocyte clusters in the superficial zone of the ankle with respect to age, gender, or site on the cartilage surface. Adjacent to a lesion in an ankle joint with degenerative changes, the clusters were larger, containing up to 22 chondrocytes. This is the first report documenting the presence of multiple chondrons in the superficial zone of normal human adult articular cartilage.     

Retain or sacrifice the posterior cruciate ligament in total knee arthroplasty? A histopathological study of the cruciate ligament in osteoarthritic and rheumatoid disease

BACKGROUND: The decision whether to retain or resect the posterior cruciate ligament in total knee arthroplasty is at present determined clinically by preoperative radiological variables focusing upon the amount of joint destruction, and subsequent soft tissue contractures. However, these variables give only indirect information on the histological integrity and proprioceptive properties of the posterior cruciate ligament. METHODS: Twenty posterior cruciate ligaments, obtained during total knee arthroplasty, were evaluated histologically to study the relation between the degree of preoperative radiological joint destruction, structural integrity of the posterior cruciate ligament and the neurological integrity of the targeted tissue. Eleven patients had osteoarthritis and nine patients rheumatoid arthritis. Haematoxylin and eosin, Alcian blue (mucoid degeneration), elastica von Gieson, Gomori (elastic fibres and collagen), and immunohistochemical staining for neural structures were used. RESULTS: In all but one of the posterior cruciate ligaments, morphologically intact neural tissue was present in the peritendineum of the ligaments. Structural integrity of the collagen framework was present in only seven posterior cruciate ligaments. These cases all had grade three or four radiological joint destruction. In 13 of the specimens a certain degree of mucoid degeneration of collagen was present. All patients with grade five radiological knee joint destruction displayed mucoid degeneration and irregularity of the posterior cruciate ligament fibres. CONCLUSION: Because of the extensive architectural and probably functional damage of the posterior cruciate ligament in patients who have grade five radiological knee joint destruction, retention of the posterior cruciate ligament in knee prosthesis should not be advocated.     

Anatomy of the rat knee joint and fibre composition of a major articular nerve

Several recent reports discuss the role of joint nerves in arthritis. Many of these are based on studies in the rat. The aim of this study is to examine the anatomy of the rat knee joint, in search for a primary articular nerve, and to analyze the fibre composition of that nerve. The results show that the structure of the joint differs in some respects from the human knee. At the upper end of the bony patella a cartilaginous patella extends proximally, forming the anterior wall of the suprapatellar bursa. Distinct collateral ligaments are integrated in the joint capsule. The extensor digitorum longus muscle bridges the knee joint, originating from the lateral femoral epicondyle. The well-developed menisci contain pyramid-shaped ossicles. The cruciate ligaments are arranged like in the human knee. A large posterior (PAN) and a small medial (MAN) articular nerve can be identified. The PAN is composed of some 400 axons, about 80% of which are unmyelinated. All myelinated fibres are sensory. They present a unimodal size spectrum with a size range of 1-8 microns, and a predominance of small fibres. Specific denervations indicate that about 1/3 of the unmyelinated axons represent afferents, and some 2/3 are sympathetic efferents. Interestingly, neonatal capsaicin treatment did not influence the number of unmyelinated PAN axons. The functional significance of the numerous unmyelinated sympathetic and sensory PAN axons in the normal knee joint remains to be elucidated.