ISB recommendation on definitions of joint coordinate system of various joints for the reporting of human joint motion—part I: ankle, hip, and spine

www.mobilehealthmap.org 617‐442‐3200 New research shows that mobile health clinics improve health outcomes for hard to reach populations in cost‐effective and culturally competent ways . A Harvard Medical School study determined that for every dollar invested in a mobile health clinic, the US healthcare system saves $30 on average. Mobile health clinics, which offer a range of services from preventive screenings to asthma treatment, leverage their mobility to treat people in the convenience of their own communities. For example, a mobile health clinic in Baltimore, MD, has documented savings of $3,500 per child seen due to reduced asthma‐related hospitalizations. The estimated 2,000 mobile health clinics across the country are providing similarly cost‐effective access to healthcare for a wide range of populations. Many successful mobile health clinics cite their ability to foster trusting relationships. Qualitative research in such mobile health clinics has found that patients value the informal, familiar environment in a convenient location, with staff who “are easy to talk to,” and that the staff’s “marriage of professional and personal discourses” provides patients the space to disclose information themselves. A communications academic argued that mobile health clinics’ unique use of space is important in facilitating these relationships. Mobile health clinics park in the heart of the community in familiar spaces, like shopping centers or bus stations, which lend themselves to the local community atmosphere.

Unequal Treatment: Confronting Racial and Ethnic Disparities in Health Care

In view of the current level of knowledge and the numerous treatment possibilities, none of the existing classification systems of thoracic and lumbar injuries is completely satisfactory As a result of more than a decade of consideration of the subject matter and a review of 1445 consecutive thoracolumbar injuries, a comprehensive classification of thoracic and lumbar injuries is proposed The classification is primarily based on pathomorphological criteria Categories are established according to the main mechanism of injury, pathomorphological uniformity, and in consideration of prognostic aspects regarding healing potential The classification reflects a progressive scale of morphological damage by which the degree of instability is determined The severity of the injury in terms of instability is expressed by its ranking within the classification system A simple grid, the 3-3-3 scheme of the AO fracture classification, was used in grouping the injuries This grid consists of three types: A, B, and C Every type has three groups, each of which contains three subgroups with specifications The types have a fundamental injury pattern which is determined by the three most important mechanisms acting on the spine: compression, distraction, and axial torque Type A (vertebral body compression) focuses on injury patterns of the vertebral body Type B injuries (anterior and posterior element injuries with distraction) are characterized by transverse disruption either anteriorly or posteriorly Type C lesions (anterior and posterior element injuries with rotation) describe injury patterns resulting from axial torque The latter are most often superimposed on either type A or type B lesions Morphological criteria are predominantly used for further subdivision of the injuries Severity progresses from type A through type C as well as within the types, groups, and further subdivisions The 1445 cases were analyzed with regard to the level of the main injury, the frequency of types and groups, and the incidence of neurological deficit Most injuries occurred around the thoracolumbar junction The upper and lower end of the thoracolumbar spine and the T 10 level were most infrequently injured Type A fractures were found in 661 %, type B in 145%, and type C in 194% of the cases Stable type Al fractures accounted for 347% of the total Some injury patterns are typical for certain sections of the thoracolumbar spine and others for age groups The neurological deficit, ranging from complete paraplegia to a single root lesion, was evaluated in 1212 cases The overall incidence was 22% and increased significantly from type to type: neurological deficit was present in 14% of type A, 32% of type B, and 55% of type C lesions Only 2% of the Al and 4% of the A2 fractures showed any neurological deficit The classification is comprehensive as almost any injury can be itemized according to easily recognizable and consistent radiographic and clinical findings Every injury can be defined alphanumerically or by a descriptive name The classification can, however, also be used in an abbreviated form without impairment of the information most important for clinical practice Identification of the fundamental nature of an injury is facilitated by a simple algorithm Recognizing the nature of the injury, its degree of instability, and prognostic aspects are decisive for the choice of the most appropriate treatment Experience has shown that the new classification is especially useful in this respect

A comprehensive classification of thoracic and lumbar injuries

Background: We studied the incidence, prevalence, and radiographic progression of symptomatic adjacent-segment disease, which we defined as the development of new radiculopathy or myelopathy referable to a motion segment adjacent to the site of a previous anterior arthrodesis of the cervical spine. Methods: A consecutive series of 374 patients who had a total of 409 anterior cervical arthrodeses for the treatment of cervical spondylosis with radiculopathy or myelopathy, or both, were followed for a maximum of twenty-one years after the operation. The annual incidence of symptomatic adjacent-segment disease was defined as the percentage of patients who had been disease-free at the start of a given year of follow-up in whom new disease developed during that year. The prevalence was defined as the percentage of all patients in whom symptomatic adjacent-segment disease developed within a given period of follow-up. The natural history of the disease was predicted with use of a Kaplan-Meier survivorship analysis. The hypothesis that new disease at an adjacent level is more likely to develop following a multilevel arthrodesis than it is following a single-level arthrodesis was tested with logistic regression. Results: Symptomatic adjacent-segment disease occurred at a relatively constant incidence of 2.9 percent per year (range, 0.0 to 4.8 percent per year) during the ten years after the operation. Survivorship analysis predicted that 25.6 percent of the patients (95 percent confidence interval, 20 to 32 percent) who had an anterior cervical arthrodesis would have new disease at an adjacent level within ten years after the operation. There were highly significant differences among the motion segments with regard to the likelihood of symptomatic adjacent-segment disease (p < 0.0001); the greatest risk was at the interspaces between the fifth and sixth and between the sixth and seventh cervical vertebrae. Contrary to our hypothesis, we found that the risk of new disease at an adjacent level was significantly lower following a multilevel arthrodesis than it was following a single-level arthrodesis (p < 0.001). More than two-thirds of all patients in whom the new disease developed had failure of nonoperative management and needed additional operative procedures. Conclusions: Symptomatic adjacent-segment disease may affect more than one-fourth of all patients within ten years after an anterior cervical arthrodesis. A single-level arthrodesis involving the fifth or sixth cervical vertebra and preexisting radiographic evidence of degeneration at adjacent levels appear to be the greatest risk factors for new disease. Therefore, we believe that all degenerated segments causing radiculopathy or myelopathy should be included in an anterior cervical arthrodesis. Although our findings suggest that symptomatic adjacent-segment disease is the result of progressive spondylosis, patients should be informed of the substantial possibility that new disease will develop at an adjacent level over the long term.

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Radiculopathy and Myelopathy at Segments Adjacent to the Site of a Previous Anterior Cervical Arthrodesis

and Introduction Abstract Study Design: Review and reinterpretation of existing literature. Objective: To suggest how intervertebral disc degeneration might be distinguished from the physiologic processes of growth, aging, healing, and adaptive remodeling. Summary of Background Data: The research literature concerning disc degeneration is particularly diverse, and there are no accepted definitions to guide biomedical research, or medicolegal practice. Definitions: The process of disc degeneration is an aberrant, cell-mediated response to progressive structural failure. A degenerate disc is one with structural failure combined with accelerated or advanced signs of aging. Early degenerative changes should refer to accelerated age-related changes in a structurally intact disc. Degenerative disc disease should be applied to a degenerate disc that is also painful. Justification: Structural defects such as endplate fracture, radial fissures, and herniation are easily detected, unambiguous markers of impaired disc function. They are not inevitable with age and are more closely related to pain than any other feature of aging discs. Structural failure is irreversible because adult discs have limited healing potential. It also progresses by physical and biologic mechanisms, and, therefore, is a suitable marker for a degenerative process. Biologic progression occurs because structural failure uncouples the local mechanical environment of disc cells from the overall loading of the disc, so that disc cell responses can be inappropriate or aberrant. Animal models confirm that cell-mediated changes always follow structural failure caused by trauma. This definition of disc degeneration simplifies the issue of causality: excessive mechanical loading disrupts a disc's structure and precipitates a cascade of cell-mediated responses, leading to further disruption. Underlying causes of disc degeneration include genetic inheritance, age, inadequate metabolite transport, and loading history, all of which can weaken discs to such an extent that structural failure occurs during the activities of daily living. The other closely related definitions help to distinguish between degenerate and injured discs, and between discs that are and are not painful.

What is intervertebral disc degeneration, and what causes it?

Combining orthopedic surgery with biomechanical engineering, this reference and teaching text reviews and analyzes the clinical and scientific data on the mechanics of the human spine. This edition adds new material on vibration (i.e. road driving) and its effect on the spine; anatomy and kinematics

Clinical Biomechanics of the Spine

An epidemiologic study of lifting and twisting on the job and risk for acute prolapsed lumbar intervertebral disc

We performed quantitative computed tomography in vitro on the first and third lumbar vertebrae in human cadavera using a dibasic potassium phosphate phantom for calibration. The quantitative computed-tomography numbers exhibited a significant positive correlation (R2 = 0.89, p less than 0.0001) with direct measurements of the apparent density of the vertebral trabecular bone. We also conducted uniaxial compression tests to failure of the vertebral bodies after removal of the posterior elements, and found that vertebral compressive strength was also correlated at a high level of significance (R2 = 0.82, p less than 0.0001) with direct measurement of the trabecular apparent density. These findings suggested the possibility that the quantitative computed-tomography values might be directly predictive of vertebral compressive strength. However, when we correlated the quantitative computed-tomography values directly with vertebral compressive strength, the results (R2 = 0.46, p less than 0.061) were suggestive but not quite significant. All vertebral bodies failed by compression of the end-plate, suggesting only a modest structural role for the cortical shell under these loading conditions. This was confirmed by comparing the compressive load to failure of twenty additional pairs of vertebrae that were tested with and without an intact vertebral cortex. Removal of the cortex was associated with approximately 10 per cent reduction in vertebral load to failure.

Prediction of vertebral body compressive fracture using quantitative computed tomography.

The treatment of fractures of the dens is often inadequate, and surgeons are divided in their opinions regarding the best surgical management of these potentially serious injuries Because of these concerns, the Cervical Spine Research Society conducted a multicenter survey of its membership regarding the management of these fractures Fractures of the dens can be effectively classified according to the anatomical level of the fracture, as described by Anderson and d'Alonzo We have found that the degree of angulation and amount of displacement are also important factors Fractures occurring at the junction of the dens with the vertebral body (Type-II fractures) were found to be the most troublesome The initial management of these fractures with a halo device was successful in only 68 per cent; however, posterior cervical fusion was successful in 96 per cent, and that appears to be the treatment of choice Fractures extending into the vertebral body (Type-III injuries) were found not to be as benign as has been reported Malunion and non-union occurred in patients with this injury who were treated with an orthosis alone, and a halo device or surgery may be indicated for unstable lesions

Augustus A. White

Papers

Clinical Biomechanics of the Spine

An epidemiologic study of lifting and twisting on the job and risk for acute prolapsed lumbar intervertebral disc

Prediction of vertebral body compressive fracture using quantitative computed tomography.

Fractures of the dens. A multicenter study.

Three-dimensional flexibility and stiffness properties of the human thoracic spine