Identification of resilin in the leg of cockroach, Periplaneta americana: confirmation by a simple method using pH dependence of UV fluorescence

We have examined the tarsus (foot) and tibial segments of the cockroach leg to identify structures that contain the elastic protein resilin. The presence of resilin was tested using the conventional criteria of fluorescent emission at 420 nm under UV illumination and histological staining of wholemount tissues by toluidine blue. We have also developed a simple method of confirming identification of resilin through changes in its fluorescence that occur with alteration of pH of the surrounding medium. Using a commonly available excitation filter that only passes light at >330 nm, we found that the emission was present at neutral pH but was eliminated at low pH. It then reversibly reappeared when medium of higher pH was restored. This effect is attributable to a known shift in the absorption maximum of amino acids of resilin that occurs in acidic media (from 330 to 285 nm). The accuracy of this method of identification was confirmed by examination of ligaments of the wing hinge, which has previously been shown to contain resilin in a number of insects. Using these techniques, we have identified resilin in association with ligaments at the tibio-tarsal joint and in the articulation between the fourth and fifth tarsal segments of the leg. The anatomical arrangement of these ligaments suggests that they could aid in the generation of leg movements during walking by functioning as elastic antagonists to the actions of leg muscles. The method of identification we have devised could readily be applied to aid in the localization of resilin in other animals.     

The effect of damage to the lateral collateral ligaments on the mechanical characteristics of the ankle joint--an in-vitro study

Injuries to the lateral collateral ligaments of the ankle joint are among the most frequently occurring injuries at the lower limb. The present study was conducted for the purpose of establishing the basis for the development of a quantitative diagnostic procedure for such injuries. To achieve this goal, the effect of four types of ligament injuries on the three-dimensional mechanical characteristics of the ankle were investigated. These types of injuries consisted of: 1) isolated tear of the anterior talofibular ligament; 2) isolated tear of the calcaneofibular ligament; 3) isolated tear of the posterior talofibular ligament; and 4) combined tear of both the anterior talofibular ligament and the calcaneofibular ligament. The experiments were conducted on 31 amputated lower limbs and consisted of comparing the three-dimensional load-displacement and flexibility characteristics of the ankle joint prior to and following sectioning of selected ligaments. The experimental and analytical procedures used to derive these characteristics was developed previously by the authors. From the results of this study it was concluded that the three-dimensional flexibility characteristics of the ankle joint are strongly influenced by damage to the lateral collateral ligaments. Furthermore, it was found that each type of ligament injury produced unique and identifiably changes in the flexibility characteristics of the ankle. These unique changes, which are described in detail in this paper, can be used to discriminate between the different types of ligament injuries. Consequently, it was concluded that it is feasible to develop a quantitative diagnostic procedure for ankle ligament injuries based on the effect of the injury on the flexibility characteristics of the ankle.     

A role for calcitonin gene-related peptide in rabbit knee joint ligament healing

Knee joint ligament healing has been shown to be improved when the torn ligament ends remain in contact, however, the rationale for these effects is unknown. The sensory neuropeptide calcitonin gene related peptide (CGRP) has potent trophic and vasodilatatory properties and as such is thought to be advantageous in wound repair. In ascertaining a role for CGRP in rabbit medial collateral ligament healing, the present study examined changes in CGRP-like immunoreactivity (CGRP-LI) and CGRP-mediated vasomotor responses in gap injured (non-contact), Z-plasty apposed (contact), and sham operated control medial collateral ligaments. At 6 weeks post-trauma, CGRP-LI decreased in the healing zone of gap injured and Z-plasty apposed medial collateral ligaments compared with controls, and non-contact ligament nerve fibres exhibited an abnormal morphology. Topical administration of CGRP (10(-13) to 10(-9) mol) caused a dose-dependent increase in ligament perfusion in each experimental group of knees. The CGRP-mediated vasodilatation associated with gap injured ligaments was not significantly different from controls (P = 0.06), whereas apposed medial collateral ligaments showed an augmented response to the peptide (P < 0.0005). These findings indicate that the beneficial effects of ligament interposition post-trauma may be related to an enhanced responsiveness to CGRP in conjunction with a more typical re-innervation profile. Conversely, the aberrant characteristics of CGRP-LI nerves occurring in gap injured tissue is suggestive of impaired CGRP release which may explain the poor functional recovery associated with these ligaments.     

The effect of boundary condition on the biomechanics of a human pelvic joint under an axial compressive load: a three-dimensional finite element model

The finite element (FE) model of the pelvic joint is helpful for clinical diagnosis and treatment of pelvic injuries. However, the effect of an FE model boundary condition on the biomechanical behavior of a pelvic joint has not been well studied. The objective of this study was to study the effect of boundary condition on the pelvic biomechanics predictions. A 3D FE model of a pelvis using subject-specific estimates of intact bone structures, main ligaments and bone material anisotropy by computed tomography (CT) gray value was developed and validated by bone surface strains obtained from rosette strain gauges in an in vitro pelvic experiment. Then three FE pelvic models were constructed to analyze the effect of boundary condition, corresponding to an intact pelvic joint, a pelvic joint without sacroiliac ligaments and a pelvic joint without proximal femurs, respectively. Vertical load was applied to the same pelvis with a fixed prosthetic femoral stem and the same load was simulated in the FE model. A strong correlation coefficient (R(2)=0.9657) was calculated, which indicated a strong correlation between the FE analysis and experimental results. The effect of boundary condition changes on the biomechanical response depended on the anatomical location and structure of the pelvic joint. It was found that acetabulum fixed in all directions with the femur removed can increase the stress distribution on the acetabular inner plate (approximately double the original values) and decrease that on the superior of pubis (from 7 MPa to 0.6 MPa). Taking sacrum and ilium as a whole, instead of sacroiliac and iliolumber ligaments, can influence the stress distribution on ilium and pubis bone vastly. These findings suggest pelvic biomechanics is very dependent on the boundary condition in the FE model.     

A three-dimensional study of the kinematics of the human knee

This paper represents a three-dimensional study of the human knee-joint and studies kinematic effects of the cruciate ligaments. Two methods were used for our studies, one method was preferred. This method used a time lapse photograph and strobe light to give us a plot of reference points to carry out our analysis using the method of Rouleaux applied to three dimensions. Five cadaver joints were used, each of which was used for three series of experiments, including the joint with capsule intact, with one of the ligaments cut and with the remaining ligament cut. Both lateral and medial studies were conducted to provide data for a three-dimensional study.

It was found that the cruciate ligaments had little effect on the kinematics of the knee, and that the knee motion remained unchanged after cutting one or both of the cruciate ligaments. It was concluded that the motion of the knee was due to the geometry of the bones and perhaps the collateral ligaments, and that the joint could be replaced with a prosthesis having a three dimensional axis of rotation with a fixed center.     

Effect of simulated joint instability and bracing on ankle and subtalar joint flexibility

It is clinically challenging to distinguish between ankle and subtalar joints instability in vivo. Understanding the changes in load-displacement at the ankle and subtalar joints after ligament injuries may detect specific changes in joint characteristics that cannot be detected by investigating changes in range of motion alone. The effect of restricting joints end range of motion with ankle braces was already established, but little is known about the effect of an ankle brace on the flexibility of the injured ankle and subtalar joints. Therefore, the purposes of this study were to (1) understand how flexibility is affected at the ankle and subtalar joints after sectioning lateral and intrinsic ligaments during combined sagittal foot position and inversion and during internal rotation and (2) investigate the effect of a semi-rigid ankle brace on the ankle and subtalar joint flexibility. Kinematics and kinetics were collected from nine cadaver feet during inversion through the range of ankle flexion and during internal rotation. Motion was applied with and without a brace on an intact foot and after sequentially sectioning the calcaneofibular ligament (CFL) and the intrinsic ligaments. Segmental flexibility was defined as the slope of the angle-moment curve for each 1 Nm interval. Early flexibility significantly increased at the ankle and subtalar joint after CFL sectioning during inversion. The semi-rigid ankle brace significantly decreased early flexibility at the subtalar joint during inversion and internal rotation for all ligament conditions and at the ankle joint after all ligaments were cut.     

Biomechanics of knee ligaments: injury, healing, and repair

Knee ligament injuries are common, particularly in sports and sports related activities. Rupture of these ligaments upsets the balance between knee mobility and stability, resulting in abnormal knee kinematics and damage to other tissues in and around the joint that lead to morbidity and pain. During the past three decades, significant advances have been made in characterizing the biomechanical and biochemical properties of knee ligaments as an individual component as well as their contribution to joint function. Further, significant knowledge on the healing process and replacement of ligaments after rupture have helped to evaluate the effectiveness of various treatment procedures. This review paper provides an overview of the current biological and biomechanical knowledge on normal knee ligaments, as well as ligament healing and reconstruction following injury. Further, it deals with new and exciting functional tissue engineering approaches (ex. growth factors, gene transfer and gene therapy, cell therapy, mechanical factors, and the use of scaffolding materials) aimed at improving the healing of ligaments as well as the interface between a replacement graft and bone. In addition, it explores the anatomical, biological and functional perspectives of current reconstruction procedures. Through the utilization of robotics technology and computational modeling, there is a better understanding of the kinematics of the knee and the in situ forces in knee ligaments and replacement grafts. The research summarized here is multidisciplinary and cutting edge that will ultimately help improve the treatment of ligament injuries. The material presented should serve as an inspiration to future investigators.     

MR Imaging of Patients with Lateral Epicondylitis of the Elbow: Is the Common Extensor Tendon an Isolated Lesion?

Objective

To investigate whether an injury of the common extensor tendon (CET) is associated with other abnormalities in the elbow joint and find the potential relationships between these imaging features by using a high-resolution magnetic resonance imaging (MRI).

Methods

Twenty-three patients were examined with 3.0 T MR. Two reviewers were recruited for MR images evaluation. Image features were recorded in terms of (1) the injury degree of CET; (2) associated injuries in the elbow joint. Spearman’s rank correlation analysis was performed to analyze the relationships between the injury degree of CET and associated abnormalities of the elbow joint, correlations were considered significant at p<0.05.

Results

Total 24 elbows in 23 patients were included. Various degrees of injuries were found in total 24 CETs (10 mild, 7 moderate and 7 severe). Associated abnormalities were detected in accompaniments of the elbow joints including ligaments, tendons, saccussynovialis and muscles. A significantly positive correlation (r = 0.877,p<0.01) was found in injuries of CET and lateral ulnar collateral ligament (LUCL).

Conclusion

Injury of the CET is not an isolated lesion for lateral picondylitis, which is mostly accompanied with other abnormalities, of which the LUCL injury is the most commonly seen in lateral epicondylitis, and there is a positive correlation between the injury degree in CET and LUCL.     

An in-vitro study of the kinematics of the normal, injured and stabilized cervical spine

The relative motion between various vertebrae of multi-level cervical ligamentous spinal segments (C2-T2), using Bryant angles, is described. A three-dimensional sonic digitizer was utilized to study the motion in flexion, extension, right lateral bending and right axial rotation. Effects of a number of injuries and stabilization (interspinous wiring and acrylic cement, PMMA) on the motion behavior of C5-C6 (injured) and C4-C5 (superior to injured) levels were investigated. The data were normalized with respect to intact specimens. The injury to capsular ligaments at C5-C6 produced a significant increase in the relative motion at C4-C5. Although the interspinous wiring reduced the motion at C5-C6 the C4-C5 motion was still higher. The application of PMMA made the motion at C4-C5 comparable to the intact specimen.     

A validated three-dimensional computational model of a human knee joint

This paper presents a three-dimensional finite element tibio-femoral joint model of a human knee that was validated using experimental data. The geometry of the joint model was obtained from magnetic resonance (MR) images of a cadaveric knee specimen. The same specimen was biomechanically tested using a robotic/universal force-moment sensor (UFS) system and knee kinematic data under anterior-posterior tibial loads (up to 100 N) were obtained. In the finite element model (FEM), cartilage was modeled as an elastic material, ligaments were represented as nonlinear elastic springs, and menisci were simulated by equivalent-resistance springs. Reference lengths (zero-load lengths) of the ligaments and stiffness of the meniscus springs were estimated using an optimization procedure that involved the minimization of the differences between the kinematics predicted by the model and those obtained experimentally. The joint kinematics and in-situ forces in the ligaments in response to axial tibial moments of up to 10 Nm were calculated using the model and were compared with published experimental data on knee specimens. It was also demonstrated that the equivalent-resistance springs representing the menisci are important for accurate calculation of knee kinematics. Thus, the methodology developed in this study can be a valuable tool for further analysis of knee joint function and could serve as a step toward the development of more advanced computational knee models.     

膝关节不稳对骨折愈合的影响（附3例临床分析）

目的：探讨膝关节不稳对骨折愈合的影响。方法：回顾性分析我院收治3例患者因早期未能准确诊治膝关节交叉韧带损伤,而导致同侧股骨干骨折术后不愈合的临床资料。我们从生物力学角度分析,交叉韧带对膝关节生理性制导及稳定作用,反之损伤后膝关节的生理运动一定程度的丧失,以及随之而来的载荷传导紊乱,从而导致膝关节不稳。膝关节不稳所引起骨折端应力改变,其对骨折愈合将产生怎样的影响。结果：如未能及时修复交叉韧带在患者股骨干骨折术后行CPM锻炼及部分负重行走时将传导以骨折断端以一种剪切、旋转的应力,同时下肢垂直的纵向压应力将难以传导至骨折端,可能导致股骨干骨折术后的延缓愈合甚至不愈合。结论：膝关节不稳定可引起同侧肢体骨折端的应力改变,可能导致骨折的延缓愈合甚至不愈合。     

Radiation diagnosis for tuberculous gonitis in children

Tuberculous knee joint lesion in children is the most common form of articular pathology. The high sociomedical significance of this disease in modern society is determined by not only its prevalence, but also economic losses caused by high disability rates in children. The purpose of the study was to determine the possibilities and place of a comprehensive radiation study in the diagnosis of tuberculous gonitis in children. Sixty patients aged 10 months to 18 years were examined. Clinical studies were comprehensively assessed, by taking into account the collected history data and orhthopedic and laboratory findings. Surgery was made in 26 children. All the patients underwent mutiprojection X-ray study, knee joint ultrasound study being made in 48 patients. Knee joint X-ray study was performed on Siregraph (Siemens) apparatuses. Real-time ultrasonography was conducted on Aloka SSD-1100 and Aloka--3500+ apparatuses, by employing a 7.5-MHz linear transducer. According to P.G. Kornev (1971), three phases were identified in the course of tuberculous gonitis. These included prearthritic (the development of primary ostitis); arthritic (articular cartilage destruction, followed by the development of secondary arthritis; and postarthritic (sequels of prior tuberculous osteomyelitis) phases. Analysis indicated that the use of the routine X-ray study in combination with ultrasound scanning in the diagnosis of tuberculous gonitis in children yielded more adequate information on tissue and knee joint structural changes and made it possible to define further policy treatment and to predict the outcomes of the disease.     

Mechanical analysis of the landing phase in heel-toe running.

Results of mechanical analyses of running may be helpful in the search for the etiology of running injuries. In this study a mechanical analysis was made of the landing phase of three trained heel-toe runners, running at their preferred speed and style. The body was modeled as a system of seven linked rigid segments, and the positions of markers defining these segments were monitored using 200 Hz video analysis. Information about the ground reaction force vector was collected using a force plate. Segment kinematics were combined with ground reaction force data for calculation of the net intersegmental forces and moments. The vertical component of the ground reaction force vector Fz was found to reach a first peak approximately 25 ms after touch-down. This peak occurs because, in the support leg, the vertical acceleration of the knee joint is not reduced relative to that of the ankle joint by rotation of the lower leg, so that the support leg segments collide with the floor. Rotation of the support upper leg, however, reduces the vertical acceleration of the hip joint relative to that of the knee joint, and thereby plays an important role in limiting the vertical forces during the first 40 ms. Between 40 and 100 ms after touch-down, the vertical forces are mainly limited by rotation of the support lower leg. At the instant that Fz reaches its first peak, net moments about ankle, knee and hip joints of the support leg are virtually zero. The net moment about the knee joint changed from -100 Nm (flexion) at touch-down to +200 Nm (extension) 50 ms after touch-down. These changes are too rapid to be explained by variations in the muscle activation levels and were ascribed to spring-like behavior of pre-activated knee flexor and knee extensor muscles. These results imply that the runners investigated had no opportunity to control the rotations of body segments during the first part of the contact phase, other than by selecting a certain geometry of the body and muscular (co-)activation levels prior to touch-down.     

Injuries from antipersonnel mines: the experience of the International Committee of the Red Cross.

OBJECTIVE--To describe and quantify patterns of injury from antipersonnel mines in terms of distribution of injury, drain on surgical resources, and residual disability. DESIGN--Retrospective analysis. SETTING--Two hospitals for patients injured in war. SUBJECTS--757 patients with injuries from antipersonnel mines. MAIN OUTCOME MEASURES--Distribution and number of injuries; number of blood transfusions; number of operations; disability. RESULTS--Pattern 1 injury results from standing on a buried mine. These patients usually sustain traumatic amputation of the foot or leg; they use most surgical time and blood and invariably require surgical amputation of one or both lower limbs. Pattern 2 injury is a more random collection of penetrating injuries caused by multiple fragments from a mine triggered near the victim. The lower limb is injured but there is less chance of traumatic amputation or subsequent surgical amputation. Injuries to the head, neck, chest, or abdomen are common. Pattern 3 injury results from handling a mine: the victim sustains severe upper limb injuries with associated face injuries. Eye injuries are common in all groups. CONCLUSIONS--Patients who survive standing on a buried mine have greatest disability. Non-combatants are at risk from these weapons; in developing countries their social and economic prospects after recovery from amputation are poor.     

Major defect to the brachial artery following blunt trauma--a five year follow-up

A 29-year-old soldier was injured when a collapsible side of an army truck fell on his left upper arm creating lesion to the brachial artery with a defect in the artery of about 10 cm in length. Injury to one brachial vein, of the same length, was also sustained without bone or neural injury. Intraoperative Doppler ultrasonography was performed. A reverse autologous saphenous vein interposition graft with a circumference similar to that of the injured brachial artery was used to perform end-to-end anastomosis between artery and reversed vein graft. The patient returned to his military formation 16 days post operatively, with a return to full military calisthenics routine 2 months after injury. Surgical and Doppler ultrasonography control was kept regularly. Excellent late result revascularization of the injured brachial artery with reversed interposition vein graft can be seen in CT angiography five years after injury.     

Analysis of the Stress and Displacement Distribution of Inferior Tibiofibular Syndesmosis Injuries Repaired with Screw Fixation: A Finite Element Study

Background

Studies of syndesmosis injuries have concentrated on cadaver models. However, they are unable to obtain exact data regarding the stress and displacement distribution of various tissues, and it is difficult to compare models. We investigated the biomechanical effects of inferior tibiofibular syndesmosis injuries (ITSIs) and screw fixation on the ankle using the finite element (FE) method.

Methodology/Principal Findings

A three-dimensional model of a healthy ankle complex was developed using computed tomography (CT) images. We established models of an ITSI and of screw fixation at the plane 2.5 cm above and parallel to the tibiotalar joint surface of the injured syndesmosis. Simulated loads were applied under three conditions: neutral position with single-foot standing and internal and external rotation of the ankle. ITSI reduced contact forces between the talus and fibula, helped periarticular ankle ligaments withstand more load-resisting movement, and increased the magnitude of displacement at the lower extreme of the tibia and fibula. ITSI fixation with a syndesmotic screw reduced contact forces in all joints, decreased the magnitude of displacement at the lower extreme of the tibia and fibula, and increased crural interosseous membrane stress.

Conclusions/significance

Severe syndesmosis injuries cause stress and displacement distribution of the ankle to change multidirectional ankle instability and should be treated by internal fixation. Though the transverse syndesmotic screw effectively stabilizes syndesmotic diastasis, it also changes stress distribution around the ankle and decreases the joint''s range of motion (ROM). Therefore, fixation should not be performed for a long period of time because it is not physiologically suitable for the ankle joint.     

Enhanced healing of cartilaginous injuries by glucosamine hydrochloride

We investigated the restorative effect of orally administered glucosamine hydrochloride (GlcN) on the experimentally produced cartilaginous injuries in rabbits. A total of three holes in the left stifle joint including one in the medial trochlear ridge and two in the trochlear sulcus (proximal and distal) of articular cartilage were made surgically using a drill. For the control group, only tap water and for the glucosamine group, a water based solution of GlcN (1 g/head) was administered daily, respectively. We observed the clinical symptoms daily and the condition of the injured part was observed visually and histologically at 3 weeks after the operation. There was no difference in body weight or general conditions between the two groups. However, in the control group, the muscle weight of the biceps of the left femur was significantly reduced (p<0.05). With respect to the medial trochlear injury, four out of six cases in the control group and five out of six cases in the glucosamine group were cured, respectively. With respect to the proximal and the distal holes in sulcus, only two out of six cases in the control group and five expansive out of six cases in the glucosamine group were cured. There was significant difference between the glucosamine group and the control with respect to healing of the proximal hole (p<0.05) and the total points (p<0.05), indicating that the artificial cartilage injuries were facilitated by GlcN. On histological examination, the injured parts were covered by fibrous connective tissues in the control, whereas in the glucosamine group, the massive proliferation of matured cartilaginous tissues was observed, and the regenerated cartilaginous tissues were surrounded by the proliferation of chondroblast cells. In the regenerated tissue, matured cartilage substrate was about to be formed. Safranin O and alcian blue stains marked significantly dense in the glucosamine group than in the control (p<0.01) in injured parts as well as in non-injured joint cartilage.     

Evaluation of a subject-specific finite-element model of the equine metacarpophalangeal joint under physiological load

The equine metacarpophalangeal (MCP) joint is frequently injured, especially by racehorses in training. Most injuries result from repetitive loading of the subchondral bone and articular cartilage rather than from acute events. The likelihood of injury is multi-factorial but the magnitude of mechanical loading and the number of loading cycles are believed to play an important role. Therefore, an important step in understanding injury is to determine the distribution of load across the articular surface during normal locomotion. A subject-specific finite-element model of the MCP joint was developed (including deformable cartilage, elastic ligaments, muscle forces and rigid representations of bone), evaluated against measurements obtained from cadaver experiments, and then loaded using data from gait experiments. The sensitivity of the model to force inputs, cartilage stiffness, and cartilage geometry was studied. The FE model predicted MCP joint torque and sesamoid bone flexion angles within 5% of experimental measurements. Muscle–tendon forces, joint loads and cartilage stresses all increased as locomotion speed increased from walking to trotting and finally cantering. Perturbations to muscle–tendon forces resulted in small changes in articular cartilage stresses, whereas variations in joint torque, cartilage geometry and stiffness produced much larger effects. Non-subject-specific cartilage geometry changed the magnitude and distribution of pressure and the von Mises stress markedly. The mean and peak cartilage stresses generally increased with an increase in cartilage stiffness. Areas of peak stress correlated qualitatively with sites of common injury, suggesting that further modelling work may elucidate the types of loading that precede joint injury and may assist in the development of techniques for injury mitigation.