| 1. |
- Brodén, Cyrus, et al.
(författare)
-
Low-dose CT-based implant motion analysis is a precise tool for early migration measurements of hip cups : a clinical study of 24 patients
- 2020
-
Ingår i: Acta Orthopaedica. - : Informa UK Limited. - 1745-3674 .- 1745-3682. ; 91:3, s. 260-265
-
Tidskriftsartikel (refereegranskat)abstract
- Background and purpose - Early implant migration is known to be a predictive factor of clinical loosening in total hip arthroplasty (THA). Radiostereometric analysis (RSA) is the gold standard used to measure early migration in patients. However, RSA requires costly, specialized imaging equipment and the image process is complex. We determined the precision of an alternative, commercially available, CT method in 3 ongoing clinical THA studies, comprising 3 different cups.Materials and methods - 24 CT double examinations of 24 hip cups were selected consecutively from 3 ongoing prospective studies: 2 primary THA (1 cemented and 1 uncemented) and 1 THA (cemented) revision study. Precision of the CT-based implant motion analysis (CTMA) system was calculated separately for each study, using both the surface anatomy of the pelvis and metal beads placed in the pelvis.Results - For the CTMA analysis using the surface anatomy of the pelvis, the precision ranged between 0.07 and 0.31 mm in translation and 0.20° and 0.39° for rotation, respectively. For the CTMA analysis using beads the precision ranged between 0.08 and 0.20 mm in translation and between 0.20° and 0.43° for rotations. The radiation dose ranged between 0.2 and 2.3 mSv.Interpretation - CTMA achieved a clinically relevant and consistent precision between the 3 different hip cups studied. The use of different hip cup types, different CT scanners, or registration method (beads or surface anatomy) had no discernible effect on precision. Therefore, CTMA without the use of bone markers could potentially be an alternative to RSA to measure early migration.
|
|
| 2. |
- Eriksson, Thomas, et al.
(författare)
-
Are low-dose CT scans a satisfactory substitute for stereoradiographs for migration studies? A preclinical test of low-dose CT scanning protocols and their application in a pilot patient.
- 2019
-
Ingår i: Acta Radiologica. - : Sage Publications. - 0284-1851 .- 1600-0455.
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Computed tomography (CT) has the potential to acquire the data needed for migration studies of orthopedic joint implants of patients who have had tantalum beads implanted at the time of joint replacement surgery. This can be accomplished with the same precision as radiostereometric analysis (RSA). Switching to CT would increase availability without the need for the specific facilities required for RSA. However, higher effective dose is a concern.PURPOSE: To investigate if migration measurements can be done with CT with an accuracy and effective dose comparable to that of conventional RSA.MATERIAL AND METHODS: Fourteen scanning protocols were tested in a hip phantom that incorporated tantalum beads and an uncemented femoral stem. The protocols were graded for clinical practice according to the three parameters of image quality, effective dose, and robustness of numerical data. After grading, the two protocols that graded best overall were applied to a pilot patient.RESULTS: All protocols produced scans in which the numerical data were sufficient for a migration analysis at least as precise as would be expected using RSA. A protocol with an effective dose of 0.70 mSv was shown to be applicable in a pilot patient.CONCLUSION: Low-dose CT scans with an effective dose comparable to a set of routine plain radiographs can be used for precise migration measurements.
|
|
| 3. |
- Eriksson, Thomas, et al.
(författare)
-
Low-dose CT of postoperative pelvic fractures : a comparison with radiography
- 2019
-
Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 60:1, s. 85-91
-
Tidskriftsartikel (refereegranskat)abstract
- Background Computed tomography (CT) is superior to conventional radiography (CR) for assessing internal fixation of pelvic fractures, but with a higher radiation exposure. Low-dose CT (LDCT) could possibly have a sufficient diagnostic accuracy but with a lower radiation dose. Purpose To compare postoperative diagnostic accuracy of LDCT and CR after open reduction and internal fixation of pelvic fracture. Material and Methods Twenty-one patients were examined with LDCT and CR 0-9 days after surgery. The examinations were reviewed by two musculoskeletal radiologists. Hardware, degree of fracture reduction, image quality, and reviewing time were assessed, and effective radiation dose was calculated. Inter-reader agreement was calculated. Results LDCT was significantly better than CR in determining whether hardware positioning was assessable ( P < 0.001). Acetabular congruence was assessable in all fractured patients with LDCT. In 12 of the 32 assessments with CR of patients with an acetabular fracture, joint congruence was not assessable due to overlapping hardware ( P = 0.001). Image quality was significantly higher for LDCT. Median time to review was 240 s for LDCT compared to 180 s for CR. Effective dose was 0.79 mSv for LDCT compared to 0.32 mSv for CR ( P < 0.001). Conclusion LDCT is more reliable than CR in assessing hardware position and fracture reduction. Joint congruency is sometimes not possible to assess with CR, due to overlapping hardware. The image quality is higher, but also the effective dose, with LDCT than with CR.
|
|
| 4. |
- Geijer, Mats, et al.
(författare)
-
MR appearance of the temporal evolution and resolution of spontaneous osteonecrosis of the knee : a case report
- 2017
-
Ingår i: Acta Radiologica Open. - : SAGE Publications. - 2058-4601. ; 6:2
-
Tidskriftsartikel (refereegranskat)abstract
- Spontaneous osteonecrosis of the knee (SONK) is a feared condition of unknown cause, in its classic form appearing in the medial femoral condyle in middle-aged or elderly subjects. Diagnosis with radiography is notoriously difficult with a long latency before typical changes appear. Magnetic resonance imaging (MRI) is regarded as a diagnostic tool with the possibility to give an earlier diagnosis with improved chances for treatment. However, also with MRI there may be an initial diagnostic blind spot before typical changes appear. Little is known about the temporal evolution of the MRI changes. In the current case report, a case of SONK is reported where serial imaging with MRI was performed, from initial symptoms to eventual resolution after almost three years.
|
|
| 5. |
- Hailer, Nils, et al.
(författare)
-
Chronic obstructive pulmonary disease, younger age and impaired preoperative flexion increase the risk of stiffness after total knee arthroplasty : a retrospective case–control study
- 2013
-
Ingår i: European orthopaedics and traumatology. - : Springer Science and Business Media LLC. - 1867-4577 .- 1867-4569. ; 4:3, s. 137-145
-
Tidskriftsartikel (refereegranskat)abstract
- IntroductionKnee stiffness after total knee arthroplasty (TKA) impairs patient satisfaction and can necessitate mobilisation under anaesthesia (MUA). We investigated what factors predispose towards the need for MUA after TKA.Patients and methodsThe study population was extracted from our local arthroplasty register. Within the setting of a retrospective case/control study, we compared patients who underwent MUA after TKA (n = 35) with a randomly selected control group that did not need MUA after TKA (n = 122) using binary logistic regression analysis.ResultsWe found that the risk of MUA due to flexion below 90° was increased in patients suffering from chronic obstructive pulmonary disease (COPD) with a risk ratio (RR) of 12 (95 % confidence interval [CI] 1.7–84, p = 0.01). Increasing age decreased the risk of developing stiffness with a RR of 0.88 (CI 0.81–0.95, p < 0.001) per year. Greater preoperative flexion decreased the risk of stiffness with a RR of 0.97 (CI 0.94–1.0, p = 0.03) per degree of flexion. Gender, body mass index, medical and psychiatric comorbidities, rheumatoid arthritis, the Insall–Salvati index, and the increase in sagittal femoral diameter induced by prosthesis insertion did not significantly affect the risk of stiffness. A certain type of knee prosthesis (Natural Knee 2) was overrepresented among patients requiring MUA.Discussion and conclusionWe conclude that stiffness after TKA is more frequent in younger patients and in those with limited preoperative flexion. It is also suggested that postoperative stiffness may be associated with COPD and with the choice of certain implants.
|
|
| 6. |
- Hänni, Mari, et al.
(författare)
-
Postangioplasty restenosis followed with magnetic resonance imaging in an atherosclerotic rabbit model
- 2012
-
Ingår i: International Journal of Biomedical Imaging. - : Hindawi Publishing Corporation. - 1687-4188 .- 1687-4196. ; 2012, s. 747264-
-
Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objectives. Testing a quantitative, noninvasive method to assess postangioplasty vessel wall changes in an animal model. Material and Methods. Six New Zealand white rabbits were subjected to atherosclerotic injury, including cholesterol-enriched diet, deendothelialization, and percutaneous transluminal angioplasty (PTA) in the distal part of abdominal aorta (four weeks after deendothelialization). The animals were examined with a 1.5T MRI scanner at three times as follows: baseline (six weeks after diet start and two days after PTA) and four weeks and 10 weeks after-PTA. Inflow angiosequence (M2DI) and proton-density-weighted sequence (PDW) were performed to examine the aorta with axial slices. To identify the inner and outer vessel wall boundaries, a dynamic contour algorithm (Gradient Vector Flow Snakes) was applied to the images, followed by calculation of the vessel wall dimensions. The results were compared with histopathological analysis. Results. The wall thickness in the lesion was significantly higher than in the control region at 4 and 10 weeks, reflecting induction of experimentally created after-angioplasty lesion. At baseline, no significant difference between the two regions was present. Conclusions. It is possible to follow the development of vessel wall changes after-PTA with MRI in this rabbit model.
|
|
| 7. |
- Hänni, Mari
(författare)
-
Quantification of Arterial Wall with MRI and Image Processing
- 2002
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Quantification of atherosclerosis in vivo in animal models is of great importance when treatments against atherosclerosis are evaluated. In the studies presented in this thesis a non-invasive method combining MRI and image processing is evaluated.In the first study cholesterol-fed rabbits were examined with a clinical MRI scanner with 1,5T in field strength. By thresholding two different MRI sequences, segmentation of arterial lumen and tissues surrounding the aortic vessel wall was performed. The cholesterol-fed rabbits had significantly larger vessel wall percentage area than the healthy controls.In the second study spontaneously atherosclerotic (Watanabe) rabbits were examined with equal MRI sequences as in the first study. The images were processed with a Gradient Vector Flow snake algorithm. By applying the snake algorithm, the inner and outer boundaries of the arterial wall were identified and vessel wall area and thickness were calculated. Close agreement was obtained between MRI-snakes and histopathological measurements. Reproducibility, evaluated by comparing results from three different observers, was high.In the third study cholesterol-fed rabbits were examined after 12 weeks of diet and compared to healthy controls. MRI-snakes results were compared to histopathological area measurements of intima and media layers of the arterial wall. No significant vessel wall changes were established during this period. There was a significant correlation between the two methods when the results were compared segment-wise for each individual animal.In the fourth study 8 rabbits underwent a double injury, cholesterol diet and desendothelialization of thoracic and abdominal aorta followed by angioplasty of a 30 mm long segment in the distal part of the abdominal aorta. The abdominal aorta was examined with MRI-snakes on three different occasions: baseline, 6 weeks and 10 weeks post-PTA. A significant increase of the wall thickness in the lesioned segment compared to a proximal vessel segment was found at 6 weeks post-PTA.
|
|
| 8. |
- Hänni, Mari, et al.
(författare)
-
Quantitation of atherosclerosis by magnetic resonance imaging and 3-D morphology operators
- 1999
-
Ingår i: Magnetic Resonance Imaging. - 0730-725X .- 1873-5894. ; 17:4, s. 585-591
-
Tidskriftsartikel (refereegranskat)abstract
- The objective was to ascertain whether MRI and image processing can be used to quantify atherosclerosis by measuring wall thickness in rabbit aorta. The abdominal aortas of 2 healthy and 5 atherosclerotic rabbits were examined with a gradient-echo inflow angiography sequence (2DI) and a proton density weighted turbo-spin-echo sequence (PDW). Using thresholding by four observers and 3D morphology operators, segmentation of the artery and vein lumina was performed from the 2DI sequence, and of surrounding fat and muscle from the PDW sequence. Remaining voxels adjacent to the aortic lumen were classified as vessel wall. By measuring the vessel wall volume and the lumen volume, the wall percentage was calculated. The values were significantly higher for the diseased animals than for unaffected individuals (p < 0.01). It is concluded that aortic wall thickening in atherosclerotic rabbits can be measured quantitatively by using MRI combined with 3D morphology image processing operators.
|
|
| 9. |
- Söderman, Tomas, et al.
(författare)
-
Higher frequency of osteoarthritis in patients with ACL graft rupture than in those with intact ACL grafts 30 years after reconstruction
- 2020
-
Ingår i: Knee Surgery, Sports Traumatology, Arthroscopy. - : Springer Science and Business Media LLC. - 0942-2056 .- 1433-7347. ; 28:7, s. 2139-2146
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The aim was to assess the results of anterior cruciate ligament (ACL) reconstruction regarding graft failure, knee laxity, and osteoarthritis (OA) from a longterm perspective. It was hypothesized that intact ACL graft reduces the risk for increased OA development.METHODS: The cohort comprised 60 patients with a median follow-up 31 (range 28-33) years after ACL reconstruction. They were evaluated with magnetic resonance imaging, radiography, KT-1000 arthrometer and the pivot shift test.RESULTS: Out of the 60 patients, 30 (50%) showed an intact ACL graft and 30 (50%) a ruptured or absent ACL graft. Patients with ruptured ACL grafts had more medial tibiofemoral compartment OA than those with an intact ACL graft (p = 0.0003). OA was asymmetric in patients with ruptured ACL grafts with more OA in the medial than in the lateral tibiofemoral compartment (p = 0.013) and the patellofemoral compartment (p = 0.002). The distribution of OA between compartments was similar in patients with an intact ACL graft. KT-1000 values of anterior knee laxity were higher in patients with ruptured compared to those with intact ACL grafts (p = 0.012). Side-to-side comparisons of anterior knee laxity showed higher KT-1000 values in patients with ruptured ACL graft (p = 0.0003) and similar results in those with intact graft (p = 0.09). The pivot shift grade was higher in the group with a ruptured ACL graft (p < 0.0001).CONCLUSIONS: Median 31 (range 28-33) years after ACL reconstruction, 50% of the patients showed an intact ACL graft and no side-to-side difference regarding anterior knee laxity. Patients with ruptured ACL grafts had more OA of the medial tibiofemoral compartment than those with intact ACL grafts.LEVEL OF EVIDENCE: Retrospective cohort study, Level III.
|
|
| 10. |
- Söderman, Tomas, et al.
(författare)
-
Knee function 30 years after ACL reconstruction : a case series of 60 patients.
- 2021
-
Ingår i: Acta Orthopaedica. - : Taylor & Francis. - 1745-3674 .- 1745-3682. ; 92:6, s. 716-721
-
Tidskriftsartikel (refereegranskat)abstract
- Background and purpose - Until now, there have been no studies beyond 30 years after anterior cruciate ligament (ACL) reconstruction. We report knee function a mean 31 years after ACL reconstruction.Patients and methods - This cohort comprised a case series of 60 patients with a mean follow-up of 31 years (28-33) after ACL reconstruction. Patients were evaluated with the International Knee Documentation Committee (IKDC) objective assessment, Knee injury Osteoarthritis Outcome Score (KOOS), Tegner Activity Scale, radiography, and MRI.Results - 30 patients showed an intact ACL graft and 30 a ruptured or missing ACL graft. 40 patients had osteoarthritis in the tibiofemoral compartment and 24 patients in the patellofemoral compartment. Patients with intact ACL grafts scored higher than those with ruptured or missing ACL grafts when it comes to KOOS Sport/Rec. The Hodges Lehmann estimated median difference between groups was 15 (95% CI 0-35). The KOOS scores were lower in the group with ruptured or missing ACL grafts when compared with a healthy-knee reference group of males in terms of Pain, mean difference -8 (CI -15 to -1), Symptoms, mean difference -18 (CI -27 to -9), and Sport/Rec, mean difference -21 (CI -34 to -8). In the group with intact ACL grafts, the KOOS score was lower than a healthy-knee reference group of males in terms of Symptoms, mean difference -12 (CI -21 to -3). Scores for all subgroups of KOOS were higher in patients without osteoarthritis. The IKDC overall clinical assessment outcome was worse in patients with a ruptured or missing ACL graft. The Hodges Lehmann estimated median difference between groups was 1 (CI 0-1).Interpretation - Patients with an intact ACL graft reported higher sports activity and recreation, as measured with KOOS, than patients with a ruptured or missing ACL graft. Patients with severe osteoarthritis reported lower sports activity and recreation, as measured with KOOS.
|
|
