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- Björkman, Anders, et al.
(author)
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Factor V leiden and prothrombin gene mutation: risk factors for osteonecrosis of the femoral head in adults.
- 2004
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In: Clinical Orthopaedics and Related Research. - 0009-921X. ; :425, s. 168-172
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Journal article (peer-reviewed)abstract
- The purpose of the current study was to determine whether factor V Leiden and the prothrombin 20210A gene mutation are risk factors for osteonecrosis of the femoral head in different etiologic groups of osteonecrosis in adults and whether patients with idiopathic osteonecrosis of the femoral head have a higher frequency of thromboembolic events compared with the general population. We investigated 63 adult patients with nontraumatic osteonecrosis of the femoral head for etiologic factors, such as corticosteroid medication and alcohol abuse, and the occurrence of factor V Leiden and the prothrombin 20210A gene mutation. In 35 patients, the disease was considered idiopathic and 10 of these patients (29%) had factor V Leiden or the prothrombin 20210A gene mutation or both. Mutations in factor V or the prothrombin 20210A gene were significantly more frequent in patients with idiopathic osteonecrosis than in a population of healthy control subjects (odds ratio, 2.7; 95% confidence interval range, 1.2-5.8) and in patients with osteonecrosis caused by corticosteroid medication or alcohol abuse (odds ratio, 10.8; 95% confidence interval range, 1.4-84). 36% of patients with a gene mutation had had a thromboembolic event compared with 8% of patients without a gene mutation. Thromboembolic events were more common among patients with idiopathic osteonecrosis (17%) compared with the general population (4%) and with patients with osteonecrosis caused by corticosteroid medication or alcohol abuse (7%).
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- Björkman, Anders, et al.
(author)
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Phantom digit somatotopy: a functional magnetic resonance imaging study in forearm amputees.
- 2012
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In: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 36:1, s. 2098-2106
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Journal article (peer-reviewed)abstract
- Forearm amputees often experience non-painful sensations in their phantom when the amputation stump is touched. Cutaneous stimulation of specific stump areas may be perceived as stimulation of specific phantom fingers (stump hand map). The neuronal basis of referred phantom limb sensations is unknown. We used functional magnetic resonance imaging to demonstrate a somatotopic map of the phantom fingers in the hand region of the primary somatosensory cortex after tactile stump stimulation. The location and extent of phantom finger activation in the primary somatosensory cortex corresponded well to the location of normal fingers in a reference population. Stimulation of the stump hand map resulted in an increased bilateral activation of the primary somatosensory cortex compared with stimulation of forearm regions outside the stump hand map. Increased activation was also seen in contralateral posterior parietal cortex and premotor cortex. Ipsilateral primary somatosensory cortex activation might represent a compensatory mechanism and activation of the non-primary fronto-parietal areas might correspond to awareness of the phantom limb, which is enhanced when experiencing the referred sensations. It is concluded that phantom sensation elicited by stimulation of stump hand map areas is associated with activation of finger-specific somatotopical representations in the primary somatosensory cortex. This suggests that the primary somatosensory cortex could be a neural substrate of non-painful phantom sensations. The stump hand map phenomenon might be useful in the development of prosthetic hand devices.
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- Björkman, Anders, et al.
(author)
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Sensory qualities of the phantom hand map in the residual forearm of amputees
- 2016
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In: Journal of Rehabilitation Medicine. - : Medical Journals Sweden AB. - 1651-2081 .- 1650-1977. ; 48:4, s. 70-365
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Journal article (peer-reviewed)abstract
- OBJECTIVE: Most amputees experience referred sensations, known as a phantom hand map, on the residual forearm, where touch on specific areas is perceived as touch on the amputated hand. The aim of this study was to evaluate the sensory qualities of the phantom hand map.METHODS: In 10 traumatic forearm-amputees touch thres-holds and discriminative touch of the phantom hand map were assessed and compared with corresponding areas on the contralateral forearm. The study assessed the localization of touch on the phantom hand map, and how distinct and similar to normal touch the referred feeling was.RESULTS: Similar touch thresholds were seen in the phantom hand map and the control site. Tactile discrimination, requiring both detection of stimulus and interpretation, was significantly better in the phantom hand map.CONCLUSION: This explorative study suggests that the phantom hand map and the superior tactile discrimination seen in the phantom hand map are based on adaptations within the brain. Further studies investigating the neural basis for the phantom hand map are needed.
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- Götestrand, Simon, et al.
(author)
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Visualization of wrist anatomy - a comparison between 7T and 3T MRI
- 2022
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In: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 32:2, s. 1362-1370
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Journal article (peer-reviewed)abstract
- Objective Injuries to the wrist are, due to its small size and complex anatomical structures, difficult to assess by MR, and surgical interventions such as diagnostic arthroscopy are often necessary. Therefore, improved visualization using non-invasive methods could be of clinical value. As a first step of improvement, the purpose of this study was to evaluate visualization of anatomical structures at 7T compared with 3T MR. Methods Eighteen healthy volunteers (three males and three females from each age decade between 20 and 49 years) were examined with 7T and 3T MR. Four musculoskeletal radiologists graded 2D and 3D images on a five-level grading scale for visibility of ligaments, cartilage, nerves, trabecular bone, and tendons, as well as overall image quality (i.e., edge sharpness, perceived tissue contrast, and presence of artefacts). Statistical analysis was done using a visual grading characteristics (VGC) analysis. Results Visibility of cartilage, trabecular bone, tendons, nerves, and ligaments was graded significantly higher at 7T with an area under the curve (AUC(VGC)) of 0.62-0.88 (95% confidence interval [CI] 0.50-0.97, p = < 0.0001-0.03) using either 2D or 3D imaging. Imaging with 3T was not graded as superior to 7T for any structure. Image quality was also significantly superior at 7T, except for artefacts, where no significant differences were found. Conclusions Tendons, trabecular bone, nerves, and ligaments were all significantly better visualized at 7T compared to 3T.
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- Götestrand, Simon, et al.
(author)
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Visualization of wrist ligaments with 3D and 2D magnetic resonance imaging at 3 Tesla
- 2022
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In: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 63:3, s. 368-375
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Journal article (peer-reviewed)abstract
- Background Wrist ligaments are challenging to visualize using magnetic resonance imaging (MRI). Injuries involving the scapholunate ligament (SLL), the lunotriquetral ligament (LTL), and the triangular fibrocartilage complex (TFCC) are common and difficult to diagnose, often requiring diagnostic arthroscopy. Purpose To compare the visualization of wrist ligaments on a three-dimensional (3D) sequence with two-dimensional (2D) sequences on 3-T MRI. Material and Methods Eighteen healthy volunteers were examined with a 3D SPACE (sampling perfection with application optimized contrasts using different flip angle evolution) sequence and 2D coronal, axial, and sagittal proton density-weighted (PD) sequences. Four musculoskeletal radiologists graded the anatomical visibility of the SLL, LTL, TFCC, and the image quality, using five grades in a visual grading characteristics (VGC) evaluation. After Bonferroni correction, a P value <= 0.005 was considered statistically significant. Results The 3D images were graded significantly better than the 2D images in the visualization of the dorsal and palmar parts of the SLL and the LTL. Regarding the TFCC, the 3D images were graded significantly better for visualization of the foveal attachment. 2D imaging was not found significantly superior to 3D imaging in any aspect. Conclusion The 3D SPACE sequence was scored as superior to the 2D sequences at 3 T in the assessment of the SLL, the LTL, and the foveal attachment of the TFCC. Thus, 3D SPACE can replace 2D PD sequences when these ligaments need to be assessed.
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