Weight-bearing Lower Extremity Research Articles

Effects of an exoskeleton-assisted walking program on bone strength in wheelchair individuals with spinal cord injury: A preliminary study using imaging and serum biomarkers

BACKGROUND: Lower extremity weight bearing is a key determinant in maintaining bone density and strength. Approximately 60% of individuals with chronic spinal cord injury use a wheelchair long-term as their primary mode of locomotion—leading to a substantial reduction in lower extremity weight bearing. Unfortunately, this contributes to the development of severe sub-lesional osteoporosis, particularly at the femur and tibia, with fragility fracture rates twice those reported among the general population. Overground exoskeleton-assisted walking programs provide a novel opportunity to increase lower extremity weight bearing and mobility which may strengthen bone and mitigate fracture risks and associated complications. OBJECTIVES: To measure the immediate effects of an exoskeleton assisted walking program on lower-extremity bone strength and serum bone biomarkers in individuals with a spinal cord injury who use a wheelchair as their primary mode of locomotion. METHODS: Ten participants completed a 16-week exoskeleton assisted walking program incorporating 34 individualized 1-hour sessions, progressing from 1 to 3 sessions per week. Outcomes were measured immediately before and after completion of the intervention (±7 days). Mechanical bone properties (density, mineral content, geometry and strength indexes) were assessed using dual-energy X-ray absorptiometry (left hip, left arm, left leg) and peripheral quantitative tomography (25% left femur, 66% left tibia). Bone turnover biomarkers (bone formation = osteocalcin, bone resorption = telopeptide-c collagen) and 25-hydroxyvitamine D were assessed using fasting blood samples. Wilcoxon signed-ranked tests were used to determine pre versus post differences ( p<0.05) in outcomes and standardized effect sizes (ES) were computed. RESULTS: At the femur, statistically significant increases in cortical bone mineral density (ES=0.652) and stress-strain index (ES=0.889), as well as decreases in cortical bone mineral content (ES=0.889), cortical cross-sectional area (ES=0.889) and cortical thickness (ES=0.849) were observed. At the tibia, a statistically significant increase in polar moment of inertia (ES=0.790) was observed. Levels of 25-hydroxyvitamine D increased significantly (ES=0.693). CONCLUSION: The completion of a 16-week exoskeleton-assisted walking program elicits promising bone responses. However, due in part to a lack of statistical power, the clinical significance of these findings as well as the ultimate effect on bone strength and fracture risk remains to be confirmed. Larger clinical trials are needed. Longer intervention durations, as well as multimodality interventions (e.g., functional electrical stimulation, pharmacotherapy, dietary) may ultimately prove to be the most effective. This work was supported by the Fonds de recherche du Québec - Santé (FRQS, grant #252532) and the John R. Evans Leaders Fund of the Canada Foundation for Innovation (grant #36243). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

대학야구선수의 Y Balance Test와 하지 가동성의 관계

The purpose of this study is to present the Y Balance Test (YBT) profile of college baseball players and determine the relationship between YBT and ankle and hip mobility. The subjects of this study were 27 college baseball players. The dynamic balance ability of the lower extremities was measured using the YBT Kit. Ankle mobility was measured using the modified weight bearing lunge test(WBLT) and the non-weight bearing dorsiflexion(NWBD) range of motion(ROM) test. Hip mobility was measured for flexion and extension ROM. ROM was measured with passive ROM using a goniometer. The dynamic balance and mobility of the left and right lower extremities were compared using the paired-T test. The relationship between dynamic balance and mobility of the lower extremities was analyzed using Pearson’s correlation. The YBT results of college baseball players showed no significant difference between left and right(p＞.05). The lower extremity mobility of college baseball players was significant only in the NWBD ROM of the ankle(p=.012), and other variables were not significantly different(p＞.05). YBT right anterior reach had a significant correlation with WBLT right(r=.628, p=.000) and WBLT left(r=.507, p=.007). YBT left anterior reach had a significant correlation with WBLT right(r=.807, p=.000) and WBLT left(r=.691, p=.000). In addition, the YBT left posteromedial reach had a significant correlation with the right hip extension ROM(r=.394, p=.046). However, there was no significant correlation with other variables(p＞.05). Overall, the decrease in ankle mobility of college baseball players is related to the decrease in dynamic balance ability. In particular, the decrease in dorsiflexion mobility of the ankle in the weight-bearing lower extremity is related to the limitation of the anterior reach motion of the non-weight-bearing lower extremity. Therefore, it is recommended that college baseball players regularly evaluate their ankle mobility to improve dynamic balance ability and prevent injuries.

TU-AB-204-02: Advances in C-Arm CBCT for Cardiac Interventions

This symposium highlights advanced cone-beam CT (CBCT) technologies in four areas of emerging application in diagnostic imaging and image-guided interventions. Each area includes research that extends the spatial, temporal, and/or contrast resolution characteristics of CBCT beyond conventional limits through advances in scanner technology, acquisition protocols, and 3D image reconstruction techniques. Dr. G. Chen (University of Wisconsin) will present on the topic: Advances in C-arm CBCT for Brain Perfusion Imaging. Stroke is a leading cause of death and disability, and a fraction of people having an acute ischemic stroke are suitable candidates for endovascular therapy. Critical factors that affect both the likelihood of successful revascularization and good clinical outcome are: 1) the time between stroke onset and revascularization; and 2) the ability to distinguish patients who have a small volume of irreversibly injured brain (ischemic core) and a large volume of ischemic but salvageable brain (penumbra) from patients with a large ischemic core and little or no penumbra. Therefore, “time is brain” in the care of the stroke patients. C-arm CBCT systems widely available in angiography suites have the potential to generate non-contrast-enhanced CBCT images to exclude the presence of hemorrhage, time-resolved CBCT angiography to evaluate the site of occlusion and collaterals, and CBCT perfusion parametric images to assess the extent of the ischemic core and penumbra, thereby fulfilling the imaging requirements of a “one-stop-shop” in the angiography suite to reduce the time between onset and revascularization therapy. The challenges and opportunities to advance CBCT technology to fully enable the one-stop-shop C-arm CBCT platform for brain imaging will be discussed. Dr. R. Fahrig (Stanford University) will present on the topic: Advances in C-arm CBCT for Cardiac Interventions. With the goal of providing functional information during cardiac interventions, significant effort has been expended to improve the quantitative accuracy of C-arm CBCT reconstructions. The challenge is to improve image quality while providing very short turnaround between data acquisition and volume data visualization. Corrections for x-ray scatter, view aliasing and patient motion that require no more than 2 iterations keep processing time short while reducing artifact. Fast, multi-sweep acquisitions can be used to permit assessment of left ventricular function, and visualization of radiofrequency lesions created to treat arrhythmias. Workflows for each imaging goal have been developed and validated against gold standard clinical CT or histology. The challenges, opportunities, and limitations of the new functional C-arm CBCT imaging techniques will be discussed. Dr. W. Zbijewski (Johns Hopkins University) will present on the topic: Advances in CBCT for Orthopaedics and Bone Health Imaging. Cone-beam CT is particularly well suited for imaging of musculoskeletal extremities. Owing to the high spatial resolution of flat-panel detectors, CBCT can surpass conventional CT in imaging tasks involving bone visualization, quantitative analysis of subchondral trabecular structure, and visualization and monitoring of subtle fractures that are common in orthopedic radiology. A dedicated CBCT platform has been developed that offers flexibility in system design and provides not only a compact configuration with improved logistics for extremities imaging but also enables novel diagnostic capabilities such as imaging of weight-bearing lower extremities in a natural stance. The design, development and clinical performance of dedicated extremities CBCT systems will be presented. Advanced capabilities for quantitative volumetric assessment of joint space morphology, dual-energy image-based quantification of bone composition, and in-vivo analysis of bone microarchitecture will be discussed, along with emerging applications in the diagnosis of arthritis and osteoporosis and assessment of novel therapies. Finally, Dr. J. Boone (UC Davis) will present on the topic: Advances in CBCT for Breast Imaging. Breast CT has been studied as an imaging tool for diagnostic breast evaluation and for potential breast cancer screening. The breast CT application lends itself to CBCT because of the small dimensions of the breast, the tapered shape of the breast towards higher cone angle, and the fact that there are no bones in the breast. The performance of various generations of breast CT scanners developed in recent years will be discussed, focusing on advances in spatial resolution and image noise characteristics. The results will also demonstrate the results of clinical trials using both computer and human observers. Learning Objectives: Understand the challenges, key technological advances, and emerging opportunities of CBCT in: 1. Brain perfusion imaging, including assessment of ischemic stroke 2. Cardiac imaging for functional assessment in cardiac interventions 3. Orthopedics imaging for evaluation of musculoskeletal trauma, arthritis, and osteoporosis 4. Breast imaging for screening and diagnosis of breast cancer. Work presented in this symposium includes research support by: Siemens Healthcare (Dr. Chen); NIH and Siemens Healthcare (Dr. Fahrig); NIH and Carestream Health (Dr. Zbijewski); and NIH (Dr. Boone).

TU-AB-204-01: Advances in C-Arm CBCT for Brain Perfusion Imaging

This symposium highlights advanced cone-beam CT (CBCT) technologies in four areas of emerging application in diagnostic imaging and image-guided interventions. Each area includes research that extends the spatial, temporal, and/or contrast resolution characteristics of CBCT beyond conventional limits through advances in scanner technology, acquisition protocols, and 3D image reconstruction techniques. Dr. G. Chen (University of Wisconsin) will present on the topic: Advances in C-arm CBCT for Brain Perfusion Imaging. Stroke is a leading cause of death and disability, and a fraction of people having an acute ischemic stroke are suitable candidates for endovascular therapy. Critical factors that affect both the likelihood of successful revascularization and good clinical outcome are: 1) the time between stroke onset and revascularization; and 2) the ability to distinguish patients who have a small volume of irreversibly injured brain (ischemic core) and a large volume of ischemic but salvageable brain (penumbra) from patients with a large ischemic core and little or no penumbra. Therefore, “time is brain” in the care of the stroke patients. C-arm CBCT systems widely available in angiography suites have the potential to generate non-contrast-enhanced CBCT images to exclude the presence of hemorrhage, time-resolved CBCT angiography to evaluate the site of occlusion and collaterals, and CBCT perfusion parametric images to assess the extent of the ischemic core and penumbra, thereby fulfilling the imaging requirements of a “one-stop-shop” in the angiography suite to reduce the time between onset and revascularization therapy. The challenges and opportunities to advance CBCT technology to fully enable the one-stop-shop C-arm CBCT platform for brain imaging will be discussed. Dr. R. Fahrig (Stanford University) will present on the topic: Advances in C-arm CBCT for Cardiac Interventions. With the goal of providing functional information during cardiac interventions, significant effort has been expended to improve the quantitative accuracy of C-arm CBCT reconstructions. The challenge is to improve image quality while providing very short turnaround between data acquisition and volume data visualization. Corrections for x-ray scatter, view aliasing and patient motion that require no more than 2 iterations keep processing time short while reducing artifact. Fast, multi-sweep acquisitions can be used to permit assessment of left ventricular function, and visualization of radiofrequency lesions created to treat arrhythmias. Workflows for each imaging goal have been developed and validated against gold standard clinical CT or histology. The challenges, opportunities, and limitations of the new functional C-arm CBCT imaging techniques will be discussed. Dr. W. Zbijewski (Johns Hopkins University) will present on the topic: Advances in CBCT for Orthopaedics and Bone Health Imaging. Cone-beam CT is particularly well suited for imaging of musculoskeletal extremities. Owing to the high spatial resolution of flat-panel detectors, CBCT can surpass conventional CT in imaging tasks involving bone visualization, quantitative analysis of subchondral trabecular structure, and visualization and monitoring of subtle fractures that are common in orthopedic radiology. A dedicated CBCT platform has been developed that offers flexibility in system design and provides not only a compact configuration with improved logistics for extremities imaging but also enables novel diagnostic capabilities such as imaging of weight-bearing lower extremities in a natural stance. The design, development and clinical performance of dedicated extremities CBCT systems will be presented. Advanced capabilities for quantitative volumetric assessment of joint space morphology, dual-energy image-based quantification of bone composition, and in-vivo analysis of bone microarchitecture will be discussed, along with emerging applications in the diagnosis of arthritis and osteoporosis and assessment of novel therapies. Finally, Dr. J. Boone (UC Davis) will present on the topic: Advances in CBCT for Breast Imaging. Breast CT has been studied as an imaging tool for diagnostic breast evaluation and for potential breast cancer screening. The breast CT application lends itself to CBCT because of the small dimensions of the breast, the tapered shape of the breast towards higher cone angle, and the fact that there are no bones in the breast. The performance of various generations of breast CT scanners developed in recent years will be discussed, focusing on advances in spatial resolution and image noise characteristics. The results will also demonstrate the results of clinical trials using both computer and human observers. Learning Objectives: Understand the challenges, key technological advances, and emerging opportunities of CBCT in: 1. Brain perfusion imaging, including assessment of ischemic stroke 2. Cardiac imaging for functional assessment in cardiac interventions 3. Orthopedics imaging for evaluation of musculoskeletal trauma, arthritis, and osteoporosis 4. Breast imaging for screening and diagnosis of breast cancer. Work presented in this symposium includes research support by: Siemens Healthcare (Dr. Chen); NIH and Siemens Healthcare (Dr. Fahrig); NIH and Carestream Health (Dr. Zbijewski); and NIH (Dr. Boone).

TU-AB-204-04: Advances in CBCT for Breast Imaging

This symposium highlights advanced cone-beam CT (CBCT) technologies in four areas of emerging application in diagnostic imaging and image-guided interventions. Each area includes research that extends the spatial, temporal, and/or contrast resolution characteristics of CBCT beyond conventional limits through advances in scanner technology, acquisition protocols, and 3D image reconstruction techniques. Dr. G. Chen (University of Wisconsin) will present on the topic: Advances in C-arm CBCT for Brain Perfusion Imaging. Stroke is a leading cause of death and disability, and a fraction of people having an acute ischemic stroke are suitable candidates for endovascular therapy. Critical factors that affect both the likelihood of successful revascularization and good clinical outcome are: 1) the time between stroke onset and revascularization; and 2) the ability to distinguish patients who have a small volume of irreversibly injured brain (ischemic core) and a large volume of ischemic but salvageable brain (penumbra) from patients with a large ischemic core and little or no penumbra. Therefore, “time is brain” in the care of the stroke patients. C-arm CBCT systems widely available in angiography suites have the potential to generate non-contrast-enhanced CBCT images to exclude the presence of hemorrhage, time-resolved CBCT angiography to evaluate the site of occlusion and collaterals, and CBCT perfusion parametric images to assess the extent of the ischemic core and penumbra, thereby fulfilling the imaging requirements of a “one-stop-shop” in the angiography suite to reduce the time between onset and revascularization therapy. The challenges and opportunities to advance CBCT technology to fully enable the one-stop-shop C-arm CBCT platform for brain imaging will be discussed. Dr. R. Fahrig (Stanford University) will present on the topic: Advances in C-arm CBCT for Cardiac Interventions. With the goal of providing functional information during cardiac interventions, significant effort has been expended to improve the quantitative accuracy of C-arm CBCT reconstructions. The challenge is to improve image quality while providing very short turnaround between data acquisition and volume data visualization. Corrections for x-ray scatter, view aliasing and patient motion that require no more than 2 iterations keep processing time short while reducing artifact. Fast, multi-sweep acquisitions can be used to permit assessment of left ventricular function, and visualization of radiofrequency lesions created to treat arrhythmias. Workflows for each imaging goal have been developed and validated against gold standard clinical CT or histology. The challenges, opportunities, and limitations of the new functional C-arm CBCT imaging techniques will be discussed. Dr. W. Zbijewski (Johns Hopkins University) will present on the topic: Advances in CBCT for Orthopaedics and Bone Health Imaging. Cone-beam CT is particularly well suited for imaging of musculoskeletal extremities. Owing to the high spatial resolution of flat-panel detectors, CBCT can surpass conventional CT in imaging tasks involving bone visualization, quantitative analysis of subchondral trabecular structure, and visualization and monitoring of subtle fractures that are common in orthopedic radiology. A dedicated CBCT platform has been developed that offers flexibility in system design and provides not only a compact configuration with improved logistics for extremities imaging but also enables novel diagnostic capabilities such as imaging of weight-bearing lower extremities in a natural stance. The design, development and clinical performance of dedicated extremities CBCT systems will be presented. Advanced capabilities for quantitative volumetric assessment of joint space morphology, dual-energy image-based quantification of bone composition, and in-vivo analysis of bone microarchitecture will be discussed, along with emerging applications in the diagnosis of arthritis and osteoporosis and assessment of novel therapies. Finally, Dr. J. Boone (UC Davis) will present on the topic: Advances in CBCT for Breast Imaging. Breast CT has been studied as an imaging tool for diagnostic breast evaluation and for potential breast cancer screening. The breast CT application lends itself to CBCT because of the small dimensions of the breast, the tapered shape of the breast towards higher cone angle, and the fact that there are no bones in the breast. The performance of various generations of breast CT scanners developed in recent years will be discussed, focusing on advances in spatial resolution and image noise characteristics. The results will also demonstrate the results of clinical trials using both computer and human observers. Learning Objectives: Understand the challenges, key technological advances, and emerging opportunities of CBCT in: 1. Brain perfusion imaging, including assessment of ischemic stroke 2. Cardiac imaging for functional assessment in cardiac interventions 3. Orthopedics imaging for evaluation of musculoskeletal trauma, arthritis, and osteoporosis 4. Breast imaging for screening and diagnosis of breast cancer. Work presented in this symposium includes research support by: Siemens Healthcare (Dr. Chen); NIH and Siemens Healthcare (Dr. Fahrig); NIH and Carestream Health (Dr. Zbijewski); and NIH (Dr. Boone).

TU-AB-204-03: Advances in CBCT for Orhtopaedics and Bone Health Imaging

This symposium highlights advanced cone-beam CT (CBCT) technologies in four areas of emerging application in diagnostic imaging and image-guided interventions. Each area includes research that extends the spatial, temporal, and/or contrast resolution characteristics of CBCT beyond conventional limits through advances in scanner technology, acquisition protocols, and 3D image reconstruction techniques. Dr. G. Chen (University of Wisconsin) will present on the topic: Advances in C-arm CBCT for Brain Perfusion Imaging. Stroke is a leading cause of death and disability, and a fraction of people having an acute ischemic stroke are suitable candidates for endovascular therapy. Critical factors that affect both the likelihood of successful revascularization and good clinical outcome are: 1) the time between stroke onset and revascularization; and 2) the ability to distinguish patients who have a small volume of irreversibly injured brain (ischemic core) and a large volume of ischemic but salvageable brain (penumbra) from patients with a large ischemic core and little or no penumbra. Therefore, “time is brain” in the care of the stroke patients. C-arm CBCT systems widely available in angiography suites have the potential to generate non-contrast-enhanced CBCT images to exclude the presence of hemorrhage, time-resolved CBCT angiography to evaluate the site of occlusion and collaterals, and CBCT perfusion parametric images to assess the extent of the ischemic core and penumbra, thereby fulfilling the imaging requirements of a “one-stop-shop” in the angiography suite to reduce the time between onset and revascularization therapy. The challenges and opportunities to advance CBCT technology to fully enable the one-stop-shop C-arm CBCT platform for brain imaging will be discussed. Dr. R. Fahrig (Stanford University) will present on the topic: Advances in C-arm CBCT for Cardiac Interventions. With the goal of providing functional information during cardiac interventions, significant effort has been expended to improve the quantitative accuracy of C-arm CBCT reconstructions. The challenge is to improve image quality while providing very short turnaround between data acquisition and volume data visualization. Corrections for x-ray scatter, view aliasing and patient motion that require no more than 2 iterations keep processing time short while reducing artifact. Fast, multi-sweep acquisitions can be used to permit assessment of left ventricular function, and visualization of radiofrequency lesions created to treat arrhythmias. Workflows for each imaging goal have been developed and validated against gold standard clinical CT or histology. The challenges, opportunities, and limitations of the new functional C-arm CBCT imaging techniques will be discussed. Dr. W. Zbijewski (Johns Hopkins University) will present on the topic: Advances in CBCT for Orthopaedics and Bone Health Imaging. Cone-beam CT is particularly well suited for imaging of musculoskeletal extremities. Owing to the high spatial resolution of flat-panel detectors, CBCT can surpass conventional CT in imaging tasks involving bone visualization, quantitative analysis of subchondral trabecular structure, and visualization and monitoring of subtle fractures that are common in orthopedic radiology. A dedicated CBCT platform has been developed that offers flexibility in system design and provides not only a compact configuration with improved logistics for extremities imaging but also enables novel diagnostic capabilities such as imaging of weight-bearing lower extremities in a natural stance. The design, development and clinical performance of dedicated extremities CBCT systems will be presented. Advanced capabilities for quantitative volumetric assessment of joint space morphology, dual-energy image-based quantification of bone composition, and in-vivo analysis of bone microarchitecture will be discussed, along with emerging applications in the diagnosis of arthritis and osteoporosis and assessment of novel therapies. Finally, Dr. J. Boone (UC Davis) will present on the topic: Advances in CBCT for Breast Imaging. Breast CT has been studied as an imaging tool for diagnostic breast evaluation and for potential breast cancer screening. The breast CT application lends itself to CBCT because of the small dimensions of the breast, the tapered shape of the breast towards higher cone angle, and the fact that there are no bones in the breast. The performance of various generations of breast CT scanners developed in recent years will be discussed, focusing on advances in spatial resolution and image noise characteristics. The results will also demonstrate the results of clinical trials using both computer and human observers. Learning Objectives: Understand the challenges, key technological advances, and emerging opportunities of CBCT in: 1. Brain perfusion imaging, including assessment of ischemic stroke 2. Cardiac imaging for functional assessment in cardiac interventions 3. Orthopedics imaging for evaluation of musculoskeletal trauma, arthritis, and osteoporosis 4. Breast imaging for screening and diagnosis of breast cancer. Work presented in this symposium includes research support by: Siemens Healthcare (Dr. Chen); NIH and Siemens Healthcare (Dr. Fahrig); NIH and Carestream Health (Dr. Zbijewski); and NIH (Dr. Boone).

TU-AB-204-00: Advances in Cone-Beam CT and Emerging Applications

This symposium highlights advanced cone-beam CT (CBCT) technologies in four areas of emerging application in diagnostic imaging and image-guided interventions. Each area includes research that extends the spatial, temporal, and/or contrast resolution characteristics of CBCT beyond conventional limits through advances in scanner technology, acquisition protocols, and 3D image reconstruction techniques. Dr. G. Chen (University of Wisconsin) will present on the topic: Advances in C-arm CBCT for Brain Perfusion Imaging. Stroke is a leading cause of death and disability, and a fraction of people having an acute ischemic stroke are suitable candidates for endovascular therapy. Critical factors that affect both the likelihood of successful revascularization and good clinical outcome are: 1) the time between stroke onset and revascularization; and 2) the ability to distinguish patients who have a small volume of irreversibly injured brain (ischemic core) and a large volume of ischemic but salvageable brain (penumbra) from patients with a large ischemic core and little or no penumbra. Therefore, “time is brain” in the care of the stroke patients. C-arm CBCT systems widely available in angiography suites have the potential to generate non-contrast-enhanced CBCT images to exclude the presence of hemorrhage, time-resolved CBCT angiography to evaluate the site of occlusion and collaterals, and CBCT perfusion parametric images to assess the extent of the ischemic core and penumbra, thereby fulfilling the imaging requirements of a “one-stop-shop” in the angiography suite to reduce the time between onset and revascularization therapy. The challenges and opportunities to advance CBCT technology to fully enable the one-stop-shop C-arm CBCT platform for brain imaging will be discussed. Dr. R. Fahrig (Stanford University) will present on the topic: Advances in C-arm CBCT for Cardiac Interventions. With the goal of providing functional information during cardiac interventions, significant effort has been expended to improve the quantitative accuracy of C-arm CBCT reconstructions. The challenge is to improve image quality while providing very short turnaround between data acquisition and volume data visualization. Corrections for x-ray scatter, view aliasing and patient motion that require no more than 2 iterations keep processing time short while reducing artifact. Fast, multi-sweep acquisitions can be used to permit assessment of left ventricular function, and visualization of radiofrequency lesions created to treat arrhythmias. Workflows for each imaging goal have been developed and validated against gold standard clinical CT or histology. The challenges, opportunities, and limitations of the new functional C-arm CBCT imaging techniques will be discussed. Dr. W. Zbijewski (Johns Hopkins University) will present on the topic: Advances in CBCT for Orthopaedics and Bone Health Imaging. Cone-beam CT is particularly well suited for imaging of musculoskeletal extremities. Owing to the high spatial resolution of flat-panel detectors, CBCT can surpass conventional CT in imaging tasks involving bone visualization, quantitative analysis of subchondral trabecular structure, and visualization and monitoring of subtle fractures that are common in orthopedic radiology. A dedicated CBCT platform has been developed that offers flexibility in system design and provides not only a compact configuration with improved logistics for extremities imaging but also enables novel diagnostic capabilities such as imaging of weight-bearing lower extremities in a natural stance. The design, development and clinical performance of dedicated extremities CBCT systems will be presented. Advanced capabilities for quantitative volumetric assessment of joint space morphology, dual-energy image-based quantification of bone composition, and in-vivo analysis of bone microarchitecture will be discussed, along with emerging applications in the diagnosis of arthritis and osteoporosis and assessment of novel therapies. Finally, Dr. J. Boone (UC Davis) will present on the topic: Advances in CBCT for Breast Imaging. Breast CT has been studied as an imaging tool for diagnostic breast evaluation and for potential breast cancer screening. The breast CT application lends itself to CBCT because of the small dimensions of the breast, the tapered shape of the breast towards higher cone angle, and the fact that there are no bones in the breast. The performance of various generations of breast CT scanners developed in recent years will be discussed, focusing on advances in spatial resolution and image noise characteristics. The results will also demonstrate the results of clinical trials using both computer and human observers. Learning Objectives: Understand the challenges, key technological advances, and emerging opportunities of CBCT in: 1. Brain perfusion imaging, including assessment of ischemic stroke 2. Cardiac imaging for functional assessment in cardiac interventions 3. Orthopedics imaging for evaluation of musculoskeletal trauma, arthritis, and osteoporosis 4. Breast imaging for screening and diagnosis of breast cancer. Work presented in this symposium includes research support by: Siemens Healthcare (Dr. Chen); NIH and Siemens Healthcare (Dr. Fahrig); NIH and Carestream Health (Dr. Zbijewski); and NIH (Dr. Boone).

Correction of Severe Foot and Ankle Contracture Due to CRPS Using External Fixation and Pain Management: Report of a Pediatric Case

Complex regional pain syndrome-induced dystonia is a severe deformity that can affect the lower extremities and hinder ambulation. Although a number of conservative treatments have been described for this condition, we are not aware of any publications describing the use of surgical intervention for the treatment of this condition. In this report, we describe the case of a pediatric patient with a severe lower extremity deformity in conjunction with chronic pain syndrome. A concerted, interdisciplinary treatment approach was undertaken for the management of this patient, and this included contributions from a foot and ankle surgeon, a pain specialist, an internist, a physical therapist, and a psychiatrist. The primary goal of the treatment strategy was to recreate a plantigrade, weight-bearing lower extremity, while controlling pain. To this end, gradual correction of deformity was achieved using an external fixator and, by 6 months after the surgery, the patient was for the first time in years ambulating on the realigned lower extremity. After 3 years of follow-up, she maintained an activity level that was equal to that which she enjoyed before the injury. 4.

Perception and education of unilateral weightbearing amongst health care professionals

Studies have shown that healthy individuals cannot accurately judge the degree of weightbearing through one lower extremity [Bohannon R, Waters G, Cooper J. Perception of unilateral lower extremity weightbearing during bilateral upright stance. Percept Mot Skills 69;1989:875-80]. This study of 40 healthcare professionals assessed a simple education process to see if this perception could be improved. Weightbearing was assessed before and after the education process, a familiarisation exercise with a set of bathroom scales. The education process had no significant effect on individual's perception of weightbearing, nor was there any difference between members of the multi-disciplinary team. As an important aspect of patient care, further work is necessary to identify an accurate and reproducible method of quantifying weightbearing.

Loading modalities and bone structures at nonweight-bearing upper extremity and weight-bearing lower extremity: A pQCT study of adult female athletes

This cross-sectional study of adult female athletes assessed whether the apparent loading-related differences in bone structure are primarily associated with the loading type or the muscle performance-related joint moments. Several structural variables at shaft sites of the tibia, radius and humerus, and distal sites of the tibia and radius were measured with peripheral quantitative computed tomography (pQCT) among 113 female national level athletes (representing hurdling, volleyball, soccer, racket-sports and swimming) and their 30 nonathletic referents. For the weight-bearing lower extremities, the loading modalities of the above sports were classified into high-impact (hurdling, volleyball), odd-impact (soccer, racket-sports) and repetitive, nonimpact (swimming) loadings; and for the nonweight-bearing upper extremities into high magnitude (functional weightlifting in hurdling and soccer), impact (volleyball, racket-sports) and repetitive, nonimpact (swimming) loadings. As expected, athletes' bone mass was substantially higher at loaded bone sites compared with the nonathletic referents, but more pertinently to the locomotive perspective, the loading-induced additional bone mass seemed to be used to build mechanically strong and appropriate bone structures. Compared with controls, the weight-bearing bone structures of female athletes (swimmers excluded) were characterized by larger diaphysis, thicker cortices and somewhat denser trabecular bone. The athletes' bones at the nonweight-bearing upper extremity were generally larger in cross-sectional area. The estimated indices of joint moment (muscle force × estimated lever arm) were explained from 29% to 50%, and the loading modalities from 8% to 25%, of the variance in most bone variables ( P < 0.05) of the tibia (shaft and distal site). In contrast to the weight-bearing tibia, only the estimated joint moment was positively associated ( P < 0.05) with the structural characteristics of the radius and humerus, accounting for 6% to 26% of the variance in bone variables of the shafts of these bones. Such association was not observed at the distal radius. In conclusion, at the weight-bearing lower extremity, the strong bone structure of the female athletes was attributable to muscle performance-related estimated joint moments and impact loading modality. At the shaft sites of the nonweight-bearing upper extremity, the strong bone structure was mainly attributable to the estimated joint moments. Thus, different loading history and other features of loading seemed to govern the skeletal adaptation at the upper and lower extremity.

Dynamic analysis of trunk flexion after stroke

Messier S, Bourbonnais D, Desrosiers J, Roy Y. Dynamic analysis of trunk flexion after stroke. Arch Phys Med Rehabil 2004;85:1619–24. Objective To quantify trunk movement and lower-extremity weight bearing in patients with stroke-associated hemiparesis compared with healthy subjects. Design Controlled study with 2 groups: persons with hemiparesis and healthy controls. Setting Geriatric center offering rehabilitation services. Participants A convenience sample of 15 persons with poststroke hemiparesis (age, 69.4±12.0y; ≥3mo poststroke; total motor function range, 63–95/100) on the Fugl-Meyer Assessment and of 13 healthy persons (age, 67.8±7.5y). Interventions Subjects were seated on a chair placed on a forceplate with their feet on 2 additional forceplates. A target was placed directly in front of or at a 45° angle from the midline at 66% of the nonparetic/dominant arm length. Subjects’ task was to touch the target with their forehead. Main outcome measures Amplitude and speed of trunk movements, displacement of the global center of pressure (COP), and percentage of body weight distributed on the buttocks and the feet. Results Despite speed and amplitude comparable to that of the healthy subjects (NS), subjects with hemiparesis (HS) had less COP displacement (HS, 33.7±6.9; NS, 40.5±9.2), resulting in a lower weight-bearing value on the feet (HS for the paretic foot, 2.3%±3.6%; HS for the nonparetic foot, 2.2%±2.9%; NS for the nondominant foot, 5.4%±3.4%; NS for the dominant foot, 5.2%±4.0%). Conclusions The similar amplitude of trunk flexion with a decreased displacement of COP and a lower weight bearing on the feet suggest smaller anterior displacement of the body mass. It is possible that trunk movements in persons with hemiparesis are executed by the upper trunk with very little anterior tilt of the pelvis.

Orthopaedic measurements with computed radiography: Methodological development, accuracy, and radiation dose with special reference to the weight-bearing lower extremity and the dislocating patella

The overall aim of this study was to develop and evaluate a measurement system for computed radiography (CR) and Picture Archiving and Communication Systems (PACS), permitting measurements of long distances and angles in and between related images. The developed measurement system, which was based on the QUESTOR Precision Radiography (QPR) system, was applied to the weight-bearing knee with special reference to the dislocating patella. The QPR system modified for CR fulfilled the criteria for measuring the weight-bearing knee. The special measuring assistance tools that were developed were important for the implementation of CR and PACS, particularly in workstations programmed for musculoskeletal radiology. The energy imparted to the patient was reduced by 98% at the lowest exposure of the CR-system, compared with our conventional analogue method, without loss of diagnostic accuracy. The CR technique creates a possibility, to an extent not previously feasible, to differentiate the exposure parametres (and thus minimise the radiation dose to the patient) by carefully considering the purpose of the examination. A radiographic method for measuring the rotation of the femur and the tibia, the Q-angle, and the patellar translation was developed and applied to healthy volunteers. The introduced patellar variables have yielded new insights into the complex sequence of motions between the femur, tibia, and patella. The patients with a dislocating patella were subdivided into one "clean" group of spontaneous dislocations and one group with various traumas in the history, which thus resulted in two groups with distinct radiographic differences. The Q-angle was decreased in knees that had suffered dislocations, and the traditional surgical treatment with a further reduction of the Q-angle must be challenged. The use of clinical measurements of the Q-angle was not an optimal way to evaluate the mechanical alignment in the patellofemoral joint under physiological conditions. In this study, we have proved that the developed method for CR and PACS is a useful technique for measurements in and between related images, and is superior to the conventional analogue technique.

Primary Articular Osteochondroses

Primary articular osteochondroses involve the primary articular and growth cartilage and the subjacent endochondral ossification, with resulting incongruity of the joint surface and potential degenerative osteoarthritis. Weight-bearing areas, such as the metatarsal head, are at greater risk than nonweight-bearing parts in the upper extremity, such as the capitellum of the humerus. Treatment has two phases: protected mobilization, followed by graduated functional activity; later, surgery may be required to correct the resultant degenerative osteoarthritis. The accepted period for protected mobilization of the symptomatic patient is two to three years in the upper extremity, but three years or even longer in the weight-bearing lower extremity. The longer the period of painful motion, the longer the period of indicated protected mobilization. The prognosis concerning degenerative osteoarthritis should not be estimated by the extent of acute articular involvement on roentgenograms, but rather by the duration of symptoms.