Reliability of clinically relevant 3D foot bone angles from quantitative computed tomography

BACKGROUND: Surgical treatment and clinical management of foot pathology requires accurate, reliable assessment of foot deformities. Foot and ankle deformities are multi-planar and therefore difficult to quantify by standard radiographs. Three-dimensional (3D) imaging modalities have been used to define bone orientations using inertial axes based on bone shape, but these inertial axes can fail to mimic established bone angles used in orthopaedics and clinical biomechanics. To provide improved clinical relevance of 3D bone angles, we developed techniques to define bone axes using landmarks on quantitative computed tomography (QCT) bone surface meshes. We aimed to assess measurement precision of landmark-based, 3D bone-to-bone orientations of hind foot and lesser tarsal bones for expert raters and a template-based automated method. METHODS: Two raters completed two repetitions each for twenty feet (10 right, 10 left), placing anatomic landmarks on the surfaces of calcaneus, talus, cuboid, and navicular. Landmarks were also recorded using the automated, template-based method. For each method, 3D bone axes were computed from landmark positions, and Cardan sequences produced sagittal, frontal, and transverse plane angles of bone-to-bone orientations. Angular reliability was assessed using intraclass correlation coefficients (ICCs) and the root mean square standard deviation (RMS-SD) for intra-rater and inter-rater precision, and rater versus automated agreement. RESULTS: Intra- and inter-rater ICCs were generally high (≥ 0.80), and the ICCs for each rater compared to the automated method were similarly high. RMS-SD intra-rater precision ranged from 1.4 to 3.6° and 2.4 to 6.1°, respectively, for the two raters, which compares favorably to uni-planar radiographic precision. Greatest variability was in Navicular: Talus sagittal plane angle and Cuboid: Calcaneus frontal plane angle. Precision of the automated, atlas-based template method versus the raters was comparable to each rater’s internal precision. CONCLUSIONS: Intra- and inter-rater precision suggest that the landmark-based methods have adequate test-retest reliability for 3D assessment of foot deformities. Agreement of the automated, atlas-based method with the expert raters suggests that the automated method is a valid, time-saving technique for foot deformity assessment. These methods have the potential to improve diagnosis of foot and ankle pathologies by allowing multi-planar quantification of deformities

Foot Deformity and Bone Strength in Charcot Neuropathic Osteoarthropathy

Charcot neuropathic osteoarthropathy: CN) is characterized by progressive degradation of bones and joints in a denervated, inflamed foot and ankle. Diabetes mellitus: DM) and peripheral neuropathy: PN) are the most common precursors of CN, which can lead to pedal fracture, subluxation, and dislocation. Bone injury and subtle articular damage characteristic of incipient CN are difficult to visualize with planar radiographs. As a result, CN often progresses until more serious, clinically obvious events occur, contributing to increased risk of ulceration, infection, amputation, and death. The overall purpose of this research was to develop methods using volumetric quantitative computed tomography: vQCT) to assess foot bone strength and foot deformity, in order to provide improved indices of CN onset and progression. Aim 1 describes the development of methods to assess bone mineral density: BMD) and geometric bone strength indices in human metatarsals, as well as an ex vivo validation of ultimate loading strength using cadaver samples. Results in Aim 1 showed that BMD and indices of compressive, bending, and buckling strength were strong correlates of metatarsal ultimate strength. Aim 2 provides group comparisons of vQCT-derived bone strength indices between CN and non-CN individuals, with results showing large decrements in BMD in individuals with CN, though no group differences were found for geometric strength indices. Aim 3 presents method development and reliability assessment of novel 3D techniques to assess foot deformities using bone surface atlases of the tarsal and metatarsal bones, with results suggesting that an automated, template-based method can provide equivalent measurement precision to expert testers. In Aim 4, vQCT-derived, 3D foot deformity measures were compared between CN and non-CN individuals; results showed significant alterations in bone-to-bone orientations that corroborate sagittal plane measurements from X-rays and also provide novel deformity measures that cannot be made using uni-planar X-rays. This dissertation research, completed under the direction of an interdisciplinary team of physical therapists, biomedical engineers, radiologists, and orthopedic surgeons, provides new information regarding bone strength and foot deformities in Charcot neuropathic osteoarthropathy. Most importantly, the tools developed in the course of this research have potential utility for future research to understand the pathophysiological pathways linking diabetes, peripheral neuropathy, foot deformities, and the development and progression of Charcot neuropathic osteoarthropathy

Brain and Human Body Modeling

This open access book describes modern applications of computational human modeling with specific emphasis in the areas of neurology and neuroelectromagnetics, depression and cancer treatments, radio-frequency studies and wireless communications. Special consideration is also given to the use of human modeling to the computational assessment of relevant regulatory and safety requirements. Readers working on applications that may expose human subjects to electromagnetic radiation will benefit from this book’s coverage of the latest developments in computational modelling and human phantom development to assess a given technology’s safety and efficacy in a timely manner. Describes construction and application of computational human models including anatomically detailed and subject specific models; Explains new practices in computational human modeling for neuroelectromagnetics, electromagnetic safety, and exposure evaluations; Includes a survey of modern applications for which computational human models are critical; Describes cellular-level interactions between the human body and electromagnetic fields

Brain and Human Body Modeling

This open access book describes modern applications of computational human modeling with specific emphasis in the areas of neurology and neuroelectromagnetics, depression and cancer treatments, radio-frequency studies and wireless communications. Special consideration is also given to the use of human modeling to the computational assessment of relevant regulatory and safety requirements. Readers working on applications that may expose human subjects to electromagnetic radiation will benefit from this book’s coverage of the latest developments in computational modelling and human phantom development to assess a given technology’s safety and efficacy in a timely manner. Describes construction and application of computational human models including anatomically detailed and subject specific models; Explains new practices in computational human modeling for neuroelectromagnetics, electromagnetic safety, and exposure evaluations; Includes a survey of modern applications for which computational human models are critical; Describes cellular-level interactions between the human body and electromagnetic fields

Life Sciences Program Tasks and Bibliography for FY 1996

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1996. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive Internet web page

Life Sciences Program Tasks and Bibliography

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1995. Additionally, this inaugural edition of the Task Book includes information for FY 1994 programs. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive Internet web pag

Life Sciences Program Tasks and Bibliography for FY 1997

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1997. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive internet web page