| 1. |
- Svedmark, Per, et al.
(författare)
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Broken wings : common with the Hardinger plug
- 2002
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Ingår i: Acta Orthopaedica Scandinavica. - Oslo, Norway : Taylor & Francis. - 0001-6470. ; 73:4, s. 407-408
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Tidskriftsartikel (refereegranskat)abstract
- We used the Hardinger occluder plug in 51 consecutive total hip arthroplasties. In 34 hips, 1 or more of the 12 polyethylene wings fractured and could be washed out from the canal. As many as 7 wings were loose in 2 arthroplasties. Although numerous wings were broken, no failure occurred in occlusion. The placement of loose wings in the femoral canal was studied by cementing a Charnley prosthesis in a saw-bone prepared with loose wings. The model was cut into slices. We found that the plastic wings could come into contact with both the bone and prosthesis.
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| 2. |
- Försth, Peter, 1966-, et al.
(författare)
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Motion Analysis in Lumbar Spinal Stenosis With Degenerative Spondylolisthesis : A Feasibility Study of the 3DCT Technique Comparing Laminectomy Versus Bilateral Laminotomy.
- 2018
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Ingår i: Clinical spine surgery. - : Wolters Kluwer. - 2380-0186 .- 2380-0194. ; 31:8, s. E397-E402
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Tidskriftsartikel (refereegranskat)abstract
- Study Design: This was a randomized radiologic biomechanical pilot study in vivo. Objective: The objectives of this study was to evaluate if 3-dimensional computed tomography is a feasible tool in motion analyses of the lumbar spine and to study if preservation of segmental midline structures offers less postoperative instability compared with central decompression in patients with lumbar spinal stenosis with degenerative spondylolisthesis. Summary of Background Data: The role of segmental instability after decompression is controversial. Validated techniques for biomechanical evaluation of segmental motion in human live subjects are lacking. Methods: In total, 23 patients (mean age, 68 y) with typical symptoms and magnetic resonance imaging findings of spinal stenosis with degenerative spondylolisthesis (>3 mm) in 1 or 2 adjacent lumbar levels from L3 to L5 were included. They were randomized to either laminectomy (LE) or bilateral laminotomy (LT) (preservation of the midline structures). Documentation of segmental motion was made preoperatively and 6 months postoperatively with CT in provoked flexion and extension. Analyses of movements were performed with validated software. The accuracy for this method is 0.6 mm in translation and 1 degree in rotation. Patient-reported outcome measures were collected from the Swespine register preoperatively and 2-year postoperatively. Results: The mean preoperative values for 3D rotation and translation were 6.2 degrees and 1.8 mm. The mean increase in 3D rotation 6 months after surgery was 0.25 degrees after LT and 0.7 degrees after LE (P=0.79) while the mean increase in 3D translation was 0.15 mm after LT and 1.1 mm after LE (P=0.42). Both surgeries demonstrated significant improvement in patient-reported outcome measures 2 years postoperatively. Conclusions: The 3D computed tomography technique proved to be a feasible tool in the evaluation of segmental motion in this group of older patients. There was negligible increase in segmental motion after decompressive surgery. LE with removal of the midline structures did not create a greater instability compared with when these structures were preserved.
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| 3. |
- Johansson, Fredrik, et al.
(författare)
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External training load and the association with back pain in competitive adolescent tennis players : Results from the SMASH cohort study
- 2022
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Ingår i: Sports Health. - : SAGE Publications. - 1941-0921. ; 14:1, s. 111-118
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In young tennis players, high loads on the spine and high training volumes in relation to age are associated with a high lifetime prevalence of back pain. The primary aim of this study was to investigate if accumulated external workload "spikes" in the acute:chronic workload ratio (ACWR) of tennis training, match play, and fitness training, and if high or low workload/age ratio were associated with back pain events in competitive adolescent tennis players. Additional aims were to report the incidence of back pain stratified by sex and level of play and to describe the characteristics of players with back pain.HYPOTHESIS: Rapid increases in external workload are associated with the incidence of back pain.STUDY DESIGN: Cohort study of 198 competitive tennis players, 13 to 19 years, with a weekly follow-up for 52 consecutive weeks.LEVEL OF EVIDENCE: Level 3.METHODS: Accumulated external workload spikes (uncoupled ACWR >1.3), and the workload/age ratio, were time-varying exposures in Cox regression analyses with the outcome back pain (pain intensity ≥2/10 in the lower back and/or in the upper back/neck with a pain-related disability).RESULTS: For each additional workload spike in tennis training/match play, the hazard rate ratio (HRR) was 1.17 (95% CI, 1.06-1.28) for back pain. The corresponding HRR for fitness training was 1.13 (95% CI, 1.05-1.22). Training workload/age ratio was not related to back pain.CONCLUSION: Accumulated external workload spikes of tennis training, match play, and/or fitness training are associated with a higher rate of back pain events in competitive adolescent tennis players.CLINICAL RELEVANCE: Back pain is a troublesome clinical problem that may affect the performance of talented young tennis players. Structuring the training schedule to minimize rapid increases (ie, spikes) of training load on a weekly basis may enhance performance and reduce back pain in adolescent tennis players.
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| 4. |
- Skeppholm, Martin, et al.
(författare)
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Evaluation of mobility and stability in the Discover artificial disc : an in vivo motion study using high-accuracy 3D CT data
- 2015
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Ingår i: Journal of Eurosurgery. - : AMER ASSOC NEUROLOGICAL SURGEONS. - 1547-5654 .- 1547-5646. ; 23:3, s. 383-389
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Tidskriftsartikel (refereegranskat)abstract
- OBJECT Artificial disc replacement (ADR) devices are unlike implants used in cervical fusion in that they are continuously exposed to stress not only within the implant site but also at their site of attachment to the adjacent vertebra. An imaging technique with higher accuracy than plain radiography and with the possibility of 3D visualization would provide more detailed information about the motion quality and stability of the implant in relation to the vertebrae. Such high-accuracy studies have previously been conducted with radiostereometric analysis (RSA), which requires implantation of tantalum markers in the adjacent vertebrae. The aim of this study was to evaluate in vivo motion and stability of implanted artificial discs. A noninvasive analysis was performed with CT, with an accuracy higher than that of plain radiographs and almost as high as RSA in cervical spine. METHODS Twenty-eight patients with ADR were included from a larger cohort of a randomized controlled trial comparing treatment of cervical radiculopathy with ADR or anterior cervical decompression and fusion. Surgical levels included C4-7; 18 patients had 1-level surgery and 10 patients had 2-level surgery. Follow-up time ranged from 19 to 50 months, with an average of 40 months. Two CT volumes of the cervical spine, 1 in flexion and 1 in extension, were obtained in each patient and then spatially registered using a customized imaging tool, previously used and validated for the cervical spine. Motion between the components in the artificial disc, as well as motion between the components and adjacent vertebrae, were calculated in 3 planes. Intraclass correlation (ICC) between independent observers and repeatability of the method were also calculated. RESULTS Intrinsic motion, expressed as degrees in rotation and millimeters in translation, was detectable in a majority of the ADRs. In the sagittal plane, in which the flexion/extension was performed, sagittal rotation ranged between 0.2 and 15.8 and translation between 0.0 and 5.5 mm. Eight percent of the ADRs were classified as unstable, as motion between at least 1 of the components and the adjacent vertebra was detected. Five percent were classified as ankylotic, with no detectable motion, and another 8% showed very limited motion due to heterotopic ossification. Repeatability for the motion in the sagittal plane was calculated to be 1.300 for rotation and 1.29 mm for translation (95% confidence level), ICC 0.99 and 0.84, respectively. All 3 patients with unstable devices had undergone 1-level ADRs at C5-6. They all underwent revision surgery due to increased neck pain, and instability was established during the surgery. CONCLUSIONS The majority of the artificial discs in this study showed intrinsic mobility several years after implantation and were also shown to be properly attached. Implant instability was detected in 8% of patients and, as all of these patients underwent revision surgery due to increasing neck pain, this might be a more serious problem than heterotopic bone formation.
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| 5. |
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| 6. |
- Svedmark, Per, et al.
(författare)
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A New CT Method for Assessing 3D Movements in Lumbar Facet Joints and Vertebrae in Patients before and after TDR
- 2015
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Ingår i: BioMed Research International. - : Hindawi Limited. - 2314-6133 .- 2314-6141. ; 2015, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- This study describes a 3D-CT method for analyzing facet joint motion and vertebral rotation in the lumbar spine after TDR. Ten patients were examined before and then three years after surgery, each time with two CT scans: provoked flexion and provoked extension. After 3D registration, the facet joint 3D translation and segmental vertebral 3D rotation were analyzed at the operated level (L5-S1) and adjacent level (L4-L5). Pain was evaluated using VAS. The median (±SD) 3D movement in the operated level for the left facet joint was 3.2 mm (±1.9 mm) before and 3.5 mm (±1.7 mm) after surgery and for the right facet joint was 3.0 mm (±1.0 mm) before and 3.6 mm (±1.4 mm) after surgery. The median vertebral rotation in the sagittal plane at the operated level was 5.4° (±2.3°) before surgery and 6.8° (±1.7°) after surgery and in the adjacent level was 7.7° (±4.0°) before and 9.2° (±2.7°) after surgery. The median VAS was reduced from 6 (range 5–8) to 3 (range 2–8) in extension and from 4 (range 2–6) to 2 (range 1–3) in flexion.
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| 7. |
- Svedmark, Per
(författare)
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Assessment of 3D movements in the lumbar and cervical spine with a new CT based method
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Numerous methods for measuring segmental motion in spine have been described. However, because of the inaccessibility of the spine and the complexity of segmental movements, most of the noninvasive methods in use today have low accuracy or are unable to detect movements in all three cardinal axes. Almost all in vivo methods used for analysing segmental motion are based on two-dimensional (2D) radiographic examinations. Radiostereometris Analysis is so far the most accurate method to detect three-dimensional (3D) motion. Specific aim: To develop and evaluate a non-invasive method for motion analysis of the spine using computed tomography (CT). Methods: We studied segmental motion in a custom-made spine model, healthy subjects, and a small series of patients operated with total disc replacement. The subjects and patients were examined in flexion and extension on a fourth generation spiral CT unit. Analyses of the segmental movements in lumbar and cervical spine were done with an in-house developed software tool. Results: In the lumbar spine the accuracy was 0.6 mm for translation and 1 degree for rotation in the model study. Movements of more than 1 mm could be visual detected. The repeatability on healthy subjects was 2.8 degrees in rotation and 1.8 mm in translation in vertebral segment. The mean facet joint 3D movement was for the right 6.1 mm and for the left 6.9 mm in L4-L5 segment and for the L5-S1 segment for the right facet 4.5 mm and 4.8 mm for the left. Mean rotation in the sagittal plane was 14.3 degrees in L4-L5 and 10.2 degrees in L5-S1. In patients with total disc replacement the mean rotation in the sagittal plane at the operated level (L5-S1) was 5.4 degrees before surgery and 6.8 after surgery. In the adjacent level (L4-L5) the mean rotation (degrees) was 7.7 before and 9.2 after surgery. The 3D translation in the operated level the left facet was 3.6 mm before and 4.5 mm after surgery and for the right facet joint 3.4 mm before to 3.6 mm after surgery. In the cervical spine the accuracy was 0.7 degrees in rotation and 0.5 mm in translation in the model study. The repeatability on the model was 1.1 degrees in rotation and 0.3 mm in translation. The repeatability on patients was 2.3 degrees in rotation and 1.4 mm in translation. The median movement for the patient was in the sagittal plane for rotation 6.28 and translation 0.1mm, coronal plane 1.68 and 0.6 mm, and for the transverse plane 1.38 and 0.6 mm in translation. Conclusion: We have developed a non-invasive CT based method to study the 3D segmental movement in the spine. It has been tested in a model study, on healthy subjects and on patients with total disc replacement in cervical and lumbar spine. We believe that this method for detecting movements in the spine is useful both in research and for clinical use.
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| 8. |
- Svedmark, Per, et al.
(författare)
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Model studies on segmental movement in lumbar spine using a semi-automated program for volume fusion
- 2008
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Ingår i: Journal of Computer-Aided Surgery. - London, UK : Informa Healthcare. - 1092-9088 .- 1097-0150. ; 13:1, s. 14-22
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To validate a new non-invasive CT method for measuring segmental translations in lumbar spine in a phantom using plastic vertebrae with tantalum markers and human vertebrae. Material and Methods: One hundred and four CT volumes were acquired of a phantom incorporating three lumbar vertebrae. Lumbar segmental translation was simulated by altering the position of one vertebra in all three cardinal axes between acquisitions. The CT volumes were combined into 64 case pairs, simulating lumbar segmental movement of up to 3 mm between acquisitions. The relative movement between the vertebrae was evaluated visually and numerically using a volume fusion image post-processing tool. Results were correlated to direct measurements of the phantom. Results: On visual inspection, translation of at least 1 mm or more could be safely detected and correlated with separation between the vertebrae in three dimensions. There were no significant differences between plastic and human vertebrae. Numerically, the accuracy limit for all the CT measurements of the 3D segmental translations was 0.56 mm (median: 0.12; range: -0.76 to +0.49 mm). The accuracy for the sagittal axis was 0.45 mm (median: 0.10; range: -0.46 to +0.62 mm); the accuracy for the coronal axis was 0.46 min (median: 0.09; range: -0.66 to +0.69 mm); and the accuracy for the axial axis was 0.45 mm (median: 0.05; range: -0.72 to +0.62 mm). The repeatability, calculated over 10 cases, was 0.35 mm (median: 0.16; range: -0.26 to +0.30 mm). Conclusion: The accuracy of this non-invasive method is better than that of current routine methods for detecting segmental movements. The method allows both visual and numerical evaluation of such movements. Further studies are needed to validate this method in patients.
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| 9. |
- Svedmark, Per, et al.
(författare)
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Motion analysis of total cervical disc replacements using computed tomography : Preliminary experience with nine patients and a model
- 2011
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Ingår i: Acta Radiologica. - : Sage Publications. - 0284-1851 .- 1600-0455. ; 52:10, s. 1128-1137
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Tidskriftsartikel (refereegranskat)abstract
- Background: Cervical total disc replacement (CTDR) is an alternative to anterior fusion. Therefore, it is desirable to have an accurate in vivo measurement of prosthetic kinematics and assessment of implant stability relative to the adjacent vertebrae. Purpose: To devise an in vivo CT-based method to analyze the kinematics of cervical total disc replacements (CTDR), specifically of two prosthetic components between two CT scans obtained under different conditions. Material and Methods: Nine patients with CTDR were scanned in flexion and extension of the cervical spine using a clinical CT scanner with a routine low-dose protocol. The flexion and extension CT volume data were spatially registered, and the prosthetic kinematics of two prosthetic components, an upper and a lower, was calculated and expressed in Euler angles and orthogonal linear translations relative to the upper component. For accuracy analysis, a cervical spine model incorporating the same disc replacement as used in the patients was also scanned and processed in the same manner. Results: Analysis of both the model and patients showed good repeatability, i.e. within 2 standard deviations of the mean using the 95% limits of agreement with no overlapping confidence intervals. The accuracy analysis showed that the median error was close to zero. Conclusion: The mobility of the cervical spine after total disc replacement can be effectively measured in vivo using CT. This method requires an appropriate patient positioning and scan parameters to achieve suitable image quality.
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| 10. |
- Svedmark, Per, et al.
(författare)
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Three-dimensional movements of the lumbar spine facet joints and segmental movements : in vivo examinations of normal subjects with a new non-invasive method
- 2012
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Ingår i: European spine journal. - : Springer. - 0940-6719 .- 1432-0932. ; 21:4, s. 599-605
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Tidskriftsartikel (refereegranskat)abstract
- Examination with CT and image registration is a new technique that we have previously used to assess 3D segmental motions in the lumbar spine in a phantom. Current multi-slice computed tomography (CT) offers highly accurate spatial volume resolution without significant distortion and modern CT scanners makes it possible to reduce the radiation dose to the patients. Our aim was to assess segmental movement in the lumbar spine with the aforementioned method in healthy subjects and also to determine rotation accuracy on phantom vertebrae. The subjects were examined in flexion-extension using low dose CT. Eleven healthy, asymptomatic subjects participated in the current study. The subjects were placed on a custom made jig which could provoke the lumbar spine into flexion or extension. CT examination in flexion and extension was performed. The image analysis was performed using a 3D volume fusion tool, registering one of the vertebrae, and then measuring Euler angles and distances in the registered volumes. The mean 3D facet joint translation at L4-L5 was in the right facet joint 6.1 mm (3.1-8.3), left facet joint 6.9 mm (4.9-9.9), at L5-S1: right facet joint 4.5 mm (1.4-6.9), and for the left facet joint 4.8 mm (2.0-7.7). In subjects the mean angles at the L4-L5 level were: in the sagittal plane 14.3A degrees, coronal plane 0.9A degrees (-0.6 to 2.8), and in the transverse plane 0.6A degrees (-0.4 to 1.5), in the L5-S1 level the rotation was in sagittal plane 10.2A degrees (2.4-16.1), coronal plane 0A degrees (-1.2 to 1.2), and in the transverse plane 0.2A degrees (-0.7 to 0.3). Repeated analysis for 3D facet joint movement was on average 5 mm with a standard error of mean of 0.6 mm and repeatability of 1.8 mm (CI 95%). For segmental rotation in the sagittal plane the mean rotation was 11.5A degrees and standard error of mean 1A degrees. The repeatability for rotation was 2.8A degrees (CI 95%). The accuracy for rotation in the phantom was in the sagittal plane 0.7A degrees, coronal plane 1A degrees, and 0.7 in the transverse plane. This method to assess movement in the lumbar spine is a truly 3D method with a high precision giving both visual and numerical output. We believe that this method for measuring spine movement is useful both in research and in clinical settings.
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