Dynamic and functional imaging of the musculoskeletal system

Conventional magnetic resonance imaging (MRI) examination of the musculoskeletal system is limited to static evaluation of muscle, spine, and joint morphology. However, using the variety of contrast mechanisms available with MRI, it is possible to obtain functional and biomechanical data about the musculoskeletal system. The function of joints and muscles are for motion and weight bearing, so pathology that only occurs during activity can be missed on static MRI examination. Similarly, important information about muscle biomechanics, muscle energetics, and joint function can be obtained with unique MRI contrast such as T(2)-mapping, spectroscopy, blood-oxygenation-level-dependent (BOLD) imaging, and molecular imaging. These new techniques hold the promise for a more complete and useful joint examination.     

Cardiac neuronal imaging: Application in the evaluation of cardiac disease

Conclusion  The sympathetic nervous system plays an important role in cardiovascular physiology. Both SPECT with MIBG and PET can be used to visualize the sympathetic innervation of the heart and the abnormalities in innervation caused by, for example, ischemia, heart failure, and arrhythmogenic disorders. Furthermore, cardiac neuronal imaging allows early detection of autonomic neuropathy in diabetes mellitus. Although SPECT imaging is widely available and technically less demanding than PET, the latter has important advantages. PET can be used to achieve high spatial and temporal resolution, as well as absolute quantification, in a noninvasive manner. It also can provide a wide range of different radiolabeled catecholamines, catecholamine analogs, and receptor ligands. It should be noted, however, that most experience has been obtained with SPECT and MIBG. Assessment of sympathetic nerve activity in patients with heart failure has been shown to provide important prognostic information, and cardiac neuronal imaging can potentially identify patients who are at increased risk of sudden death. Moreover, therapeutic effects of different treatment strategies can be evaluated by MIBG SPECT as well as by PET imaging. To establish the clinical utility of cardiac neuronal imaging, it will be necessary to determine the incremental value of innervation imaging to triage heart failure patients to medical therapy, CRT (with or without ICD), or heart transplantation.     

Non-neoplastic arthropathies of the temporomandibular joint

The pathologic conditions that involve the TMJ are similar to those conditions that involve other joints in the body. Therefore, many of the radiologic characteristics are also similar. Nevertheless, because of the complex structure and function of this small joint, it is essential to know the variety of diseases that can involve the temporomandibular joint. It is also important to understand that functionally both TMJ's act as a single unit and that any alteration in function caused by a pathologic process on one side may lead to dysfunction on the contralateral side. It is essential that the radiologist is familiar with the principles of TMJ function as well as TMJ pathology.     

Imaging of myocardial sympathetic innervation with metaiodobenzylguanidine

The sympathetic nervous system has profound influences on myocardial function and pathophysiology. The heart is densely innervated with sympathetic nerves, which are distributed on a regional basis. Heterogeneity of myocardial sympathetic innervation, or autonomic imbalance, has long been hypothesized as a major mechanism underlying sudden cardiac death. Only in the past few years has it been possible to evaluate abnormalities in heart innervation in the intact animal. Recent developments in cardiac imaging have lead to the ability to map the distribution of the sympathetic nerves in vivo, with radiolabeled metaiodobenzylguanidine. As a result, pathophysiologic mechanisms that relate alterations in sympathetic nerve activity to disease processes are now being explored.     

Imaging of the temporomandibular joint

The recent advances in imaging of the temporomandibular joint (TMJ), especially the introduction of MR imaging and surface colls allowing precise visualization of superficial structures led us to reconsider the different techniques used in this very complex anatomical region, due to both its morphology and function. We also tried to determine their respective role, especially in the study of TMJ dysfunction syndromes, that represent the most frequent pathology of this region. Conventional radiography allows us to appreciate the overall amplitude of the joint movements, and to study bone abnormalities, but CT is much more precise in the study of cortical bone. In TMJ dysfunction, the joint itself is studied by either arthrography or MRI, but both techniques have their limitations and remain complementary in some aspects, which are detailed here, so that the choice between them depends on availability and therapeutic indications.     

11C标记的心脏交感神经受体显像剂的研究进展

自主神经系统在调节心血管功能方面起着至关重要的作用,完整的神经支配是心血管功能正常发挥的基础。许多心脏疾病在出现临床症状之前已经出现了神经系统的改变,放射性核素标记的神经递质类似物PET显像可对此进行评估,其可以灵敏地反映心脏自主神经功能的完整性、神经元的分泌功能及活性,以便对心脏疾病进行早期诊断和及时干预。近年来11C标记的心脏交感神经受体显像剂发展迅速,笔者综述了其中几种显像剂的研究新进展。     

Schmerztherapeutische Ans?tze bei Wirbels?ulenerkrankungen

As a rule vertebroplasty and kyphoplasty can prevent further collapse of a previously broken vertebra. Pain is probably caused by collapse of the porous bone resulting in instability of the vertebra. Stabilization of the vertebra by injecting cement results in a clear improvement in the complaint and a clear reduction in pain resulting in better mobilization. Recent results have, however, cast doubt on the effectiveness of this therapy. Diagnostic nerve blocks on the spinal column are important because the pain is mostly clinically uncharacteristic, the innervation is complex and the pain is subjective. An exact classification can be made using special nerve blocks. Prerequisites for the use of diagnostic nerve blocks are an extensive clinical history and examination of the patient before nerve blocks are carried out. In approximately 15-45% of patients the zygapophyseal joint is the cause of the back pain. Anesthesia of the zygapophyseal joint can be carried out by direct intra-articular application of a local anesthetic or by a block of the medial branch of the posterior branch of each of two spinal nerves. The simplest method is by computed tomography-guided zygapophyseal block.     

Juxta-articular large cell lymphoma

Three patients with juxta-articular large cell lymphoma presented as suffering from monarthropathies. A spectrum of radiographic changes was observed that included subchondral sclerosis, regional osteopenia, effusion, and mottled lytic changes in the juxta-articular region of the affected joint. MRI was performed in two patients. In one, it revealed a high signal mass on T2-weighted sequences. In the second, a mass bridging the joint was demonstrated which was difficult to appreciate on CT and was not visible radiographically. In all cases, biopsies revealed large cell non-Hodgkin's lymphoma of bone. We present these studies to emphasize this unusual pattern of non-Hodgkin's lymphoma as well as to demonstrate the contribution of MRI to the diagnosis.     

Assessment of cardiac sympathetic neuronal function using PET imaging

The autonomic nervous system plays a key role for regulation of cardiac performance, and the importance of alterations of innervation in the pathophysiology of various heart diseases has been increasingly emphasized. Nuclear imaging techniques have been established that allow for global and regional investigation of the myocardial nervous system. The guanethidine analog iodine 123 metaiodobenzylguanidine (MIBG) has been introduced for scintigraphic mapping of presynaptic sympathetic innervation and is available today for imaging on a broad clinical basis. Not much later than MIBG, positron emission tomography (PET) has also been established for characterizing the cardiac autonomic nervous system. Although PET is methodologically demanding and less widely available, it provides substantial advantages. High spatial and temporal resolution along with routinely available attenuation correction allows for detailed definition of tracer kinetics and makes noninvasive absolute quantification a reality. Furthermore, a series of different radiolabeled catecholamines, catecholamine analogs, and receptor ligands are available. Those are often more physiologic than MIBG and well understood with regard to their tracer physiologic properties. PET imaging of sympathetic neuronal function has been successfully applied to gain mechanistic insights into myocardial biology and pathology. Available tracers allow dissection of processes of presynaptic and postsynaptic innervation contributing to cardiovascular disease. This review summarizes characteristics of currently available PET tracers for cardiac neuroimaging along with the major findings derived from their application in health and disease.     

Nerve injuries about the elbow

The ulnar, radial, median, medial antebrachial cutaneous, and lateral antebrachial cutaneous nerves are subject to traction and compression in athletes who place forceful, repetitive stresses across their elbow joint. Throwing athletes are at greatest risk, and cubital tunnel syndrome (involving the ulnar nerve) is clearly the most common neuropathy about the elbow. The anatomy and innervation pattern of the nerve involved determines the characteristic of the neuropathy syndrome. The most important parts of the work-up are the history and physical examination as electrodiagnostic testing and imaging are often not reliable. In general, active rest is the first line of treatment. Tailoring the surgery and rehabilitation protocol according to the functional requirements of that athlete's sport(s) can help optimize the operative outcomes for recalcitrant cases.     

Cryotherapy to treat persistent muscle weakness after joint injury

Cryotherapy is a widely used modality following acute joint injury. It is considered helpful in reducing pain and swelling, and there is a growing body of evidence to suggest that it may have additional benefits in muscle function. Following joint injury, it is common for patients to experience persistent muscle weakness that is resistant to traditional strengthening exercises. This may be due to a reflex inhibition of musculature surrounding the injured joint. The underlying cause of this reflex inhibition may arise from aberrant sensory information from the joints' neural receptors, which result in a neural inhibition of motor neurons. This inhibition is beyond conscious control, is ongoing, and impedes normal joint function via a disruption of normal muscle function. Cryotherapy treatments targeted at peripheral joints have been shown to result in transient resolution of reflex inhibition, which thereby provide an environment where injured patients can benefit from a more thorough motorneuron pool during controlled rehabilitation exercises. This article presents current evidence-based recommendations regarding the use of joint cryotherapy for maximizing the effectiveness of commonly used rehabilitation exercises in patients recovering from joint injury.     

Assessment of cardiac sympathetic nerve integrity with positron emission tomography

The autonomic nervous system plays a critical role in the regulation of cardiac function. Abnormalities of cardiac innervation have been implicated in the pathophysiology of many heart diseases, including sudden cardiac death and congestive heart failure. In an effort to provide clinicians with the ability to regionally map cardiac innervation, several radiotracers for imaging cardiac sympathetic neurons have been developed. This paper reviews the development of neuronal imaging agents and discusses their emerging role in the noninvasive assessment of cardiac sympathetic innervation.     

Peripheral effector mechanism hypothesis of postflight cardiovascular dysfunction

Studies on the mechanisms of cardiovascular dysfunction after space-flight are important to illustrate the cardiovascular effect of microgravity and develop appropriate multi-system countermeasures for future long-duration spaceflights. Over the past 10 yr, we have systematically studied the adaptational changes in structure and function of both the heart and vessels, using the tail-suspension rat model to simulate microgravity effects. Our results indicate that simulated microgravity induced atrophic changes and reduced contractility of the heart muscle, and upward- and downward-regulation in structure, function, and innervation state of vessels in the brain and hind body of the rat. In addition, more recent advances in relevant ground-based and space-flight studies from different laboratories have also been reviewed. Based on these studies, it has been speculated that, in addition to hypovolemia, the microgravity-induced adaptational changes in the structure and function of the two main effectors of the cardiovascular system, i.e., the arterial smooth muscle and the cardiac muscle, might be among the most important mechanisms responsible for postflight cardiovascular dysfunction and orthostatic intolerance. In this paper we will review the available evidence with comments.     

The robustness of age-related gait adaptations: Can running counterbalance the consequences of ageing?

Previous studies showed age-related redistribution of joint torques from ankle joint plantar flexion to hip joint extension in gait. In the present study it was hypothesized that running can prevent the occurrence of this joint torque redistribution. Four groups of subjects participated in this study (young and elderly both physically active and inactive). All subjects walked at a comfortable, preferred velocity and at an imposed velocity of 1.5m/s. Kinematics of lower limb segments and ground reaction forces were assessed. Inverse dynamics method was applied to determine torques around ankle, knee and hip joints. A redistribution of joint torques from plantar flexion to hip joint extension was found to occur in both active and inactive elderly. However, the active elderly had a larger increase of the hip extension torque. By this they are able to maintain the support torque at the level of young subjects. Inactive elderly displayed reduced support torques. It is concluded that the age-related redistribution of joint torques is an important phenomenon. Frequent running does not prevent this shift. Active elderly increase this redistribution to compensate for muscle function reduction.     

Neuromechanical coupling in the regulation of muscle tone and joint stiffness

The ability of the nervous system to accommodate changes to joint mechanics is crucial in the maintenance of joint stability and the prevention of injury. This neuromechanical coupling is achieved through several mechanisms such as the central and peripheral regulation of muscle tone and subsequent alterations to joint stiffness. Following joint injury, such as a ligamentous sprains, some patients develop functional instability or require surgery to stabilize the joint, while others are able to cope and display limited impairments. Several researchers have attempted to explain these divergent outcomes, although research using proprioceptive tasks and quantifying reaction times has led to equivocal results. Recent innovations have allowed for the simultaneous measurement of mechanical and nervous system function among these subsets. The intent of this review was to explore the relationships between joint stiffness and nervous system function, and how it changes following injury. By better understanding these mechanisms, researchers and clinicians may better develop and implement rehabilitation protocols to target individual deficits among injured populations.     

Changes in joint kinematics and dynamic postural stability with free and restricted arm movements in children

BackgroundArm movements make a substantial and functionally relevant contribution to quiet standing and dynamic balance tasks. The impact of restricted arm movements on balance control is particularly important for children as their postural control system is not fully matured.Research questionThis study investigated the effects of arm movements on lower body joint kinematics and dynamic postural stability during anterior and lateral dynamic movements in children.MethodsEighteen boys (age, 10.1 ± 1.6 years) completed an anterior and a lateral jump-landing task under two different verbally conveyed instructions of arm position; (1) arms placed flat across the chest touching the contralateral shoulder (i.e., restricted arm movement) and (2) arm movement without restriction. Lower body joint kinematics were recorded and used to calculate mean joint position, joint range of motion (ROM) and joint movement variability.ResultsRestricting arm movements resulted in a reduction of joint movement variability and joint ROM of the pelvis during the lateral jump (p <0.05), but increased joint movement variability and joint ROM of the pelvis during the anterior jump (p <0.05).SignificanceThe reduced joint movement variability and joint ROM with restricted arm movements during the lateral jump may represent a potential compensatory ‘stiffenin strategy’, whilst the increase during the anterior jump suggest an exploratory strategy. These novel findings highlight that it is important for children to be introduced to different dynamic task constraints so that they can learn to control and organise the motor system degrees of freedom appropriately.     

Differential diagnosis of distortion of the elbow joint

Distortion of the elbow joint often means a vague diagnosis describing a traumatized joint with no radiological changes, or it means a transient diagnosis until sophisticated examinations can demonstrate what the injury really is. In adults there are only a few injuries that cannot be shown by radiography. In children, however, radiography of the elbow joint is more difficult due to the inhomogeneity during growth. Contrary to adults, fractures misdiagnosed in radiography often result in significant reduction of joint function.     

Biomechanics of knee ligaments.

Significant advances have been made during the past 25 years in characterizing the properties of ligaments as a tissue and as an individual component in the bone-ligament-bone complex. The contribution of ligaments to joint function have also been well characterized. We have presented many studies that sought to characterize the tensile and viscoelastic properties of ligaments. As a result of these investigations, some of the most important experimental and biologic factors affecting the measurements of these properties have been identified and elucidated. The identification of the tensile properties of normal ligaments can serve as the basis for evaluating their success in healing and repair after injury. Furthermore, characterization of normal ligament function is crucial for diagnosing joint injuries as well as for evaluating reconstruction strategies and developing rehabilitation protocols. The recent introduction of robotic technology to the study of joint kinematics has resulted in significant advances in the understanding of the relative importance of ligaments to joint function. With the more accurate simulation of joint kinematics that include multiple degrees of freedom motion, data on the in situ forces in ligaments can be used to improve the treatment of ligament repair and reconstruction. More complex external loading conditions that mimic sports activities and rehabilitation protocols can also be introduced in the future. Furthermore, this technology can be extended to study other frequently injured joints, such as the shoulder.     

Technical pitfalls of collateral ligament surgery.

The technical pitfalls of collateral ligament surgery include: Failure to properly diagnose and appropriately recommend surgery; posterolateral instability is the most commonly missed acute associated instability pattern Failure to correct all components of the injury (see Table 1): lateral meniscus, arcuate ligament, and popliteus, lateral gastrocnemius, and biceps muscles Failure to properly reattach and repair the damaged structures Peroneal nerve damage during the surgical approach and repair Wound problems: breakdown, hematoma Loss of motion This article presented a concise introduction to the anatomy of the collateral and capsular ligaments of the knee. This information should prove valuable in avoiding pitfalls in the diagnostic and surgical approach to the knee. To fully appreciate the anatomy, one must study it in the anatomy laboratory by performing repeated dissections. Only then can one appreciate how beautifully all of the structures function in unison. Application of this knowledge will help surgeons continue to improve and refine their approach to knee injuries.     

Konservative Therapie und Rehabilitation von Schulterbeschwerden

The shoulder joint has an important influence on arm- and hand function. Therefore, activities of daily living, working and leisure time can be negatively influenced by diseases of the shoulder joint. Problems of the shoulder joint can be induced by muscular dysbalance and poor body posture. There is a strong relationship between shoulder function and body posture. Conservative treatment and rehabilitation of the shoulder joint aims at improving the local dysfunction of the shoulder joint as well as at improving function and social participation. Antiinflammatory and pain medication, exercise, occupational, electro-, ultrasound and shock wave therapy, massage, thermotherapy and pulsed electromagnetic fields are used as conservative treatments. Exercise therapy aims at improving muscular performance, joint mobility and body posture. Occupational therapy aims at improving functional movements for daily living and work. Electrotherapy is primarily used to relieve pain. Shock wave and ultrasound therapy proved to be an effective treatment for patients with calcific tendinitis. The subacromial impingement syndrome can be effectively treated by conservative therapy.