| 1. |
- Carlsson, Lars V, et al.
(författare)
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Stepwise introduction of a bone-conserving osseointegrated hip arthroplasty using RSA and a randomized study: I. Preliminary investigations--52 patients followed for 3 years.
- 2006
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Ingår i: Acta orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 77:4, s. 549-58
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: We developed a total hip system using osseointegration guidelines, a metaphyseal-loading proximal femoral replacement in the retained neck and a dual-geometry titanium shell in the acetabulum. PATIENTS AND METHODS: A randomized controlled clinical trial was undertaken in 52 patients (53 hips), using the cemented Spectron stem and cementless Harris-Galante II cup as control implants (24 patients in experimental group, 29 control patients). Clinical measures of Harris Hip Score (HHS), pain score and radiostereometric analysis (RSA) at regular intervals for up to three years were used to monitor progress. RESULTS: No statistically significant differences were found in HHS and pain score; the stability of the cementless experimental implant was also comparable to that of the cemented controls by RSA. 3 revisions were required for migration in the experimental group and 1 was required for component dislocation in the control group. INTERPRETATION: Our findings indicate the practicality of osseointegration of titanium implants, but suggest that current performance is inadequate for clinical introduction. However, the stable fixation achieved in the retained neck in the majority of patients is indicative of osseointegration. This finding will encourage technical and design improvements for enhancement of clinical osseointegration and should also encourage further study. Periprosthetic osteolysis might be avoided by the establishment and maintenance of direct implant-bone connection: "osseointegration".
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| 2. |
- Carlsson, Lars, 1952, et al.
(författare)
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Bone conserving hip replacement.
- 2004
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Ingår i: 3rd Annual SICOT/SIROT Conference 2004.
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Konferensbidrag (refereegranskat)
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| 3. |
- Carlsson, Lars, 1952, et al.
(författare)
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Stepwise introduction of a bone-conserving osseointegrated hip arthroplasty using RSA and a randomized study: II. Clinical proof of concept--40 patients followed for 2 years
- 2006
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Ingår i: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 77:4, s. 559-566
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: We have developed a bone-conserving commercially pure titanium hip replacement system using osseointegration principles: a metaphyseal loading proximal femoral component affixing into the retained neck and metaphysis only, leaving the femoral canal untouched. The acetabular cup closely fits a dual-geometry cavity, avoiding stress protection at the dome. PATIENTS AND METHODS: After extensive laboratory and clinical pilot trial investigations, the surface-engineered implants were submitted to a prospective randomized controlled clinical trial involving 40 patients (40 hips), in which they were compared to the cemented Spectron femoral component and cementless Trilogy cup as control implant. The following clinical measures were used to monitor progress at regular intervals for the first 2 postoperative years: radiostereometric analysis (RSA), Harris Hip Score, pain score, WOMAC, and SF-36. RESULTS: After 2 years of follow-up, no statistically significant differences were seen between the groups concerning rotation or translation along the cardinal axes. The patients receiving the Gothenburg osseointegrated titanium (GOT) system had significantly higher Harris Hip Score at 6 months, suggesting more rapid recovery. WOMAC, SF-36 and pain analysis were similar for the first 2 postoperative years. INTERPRETATION: Our RSA data suggest that osseointegration was achieved for all patients receiving the GOT hip system. This bone-conserving prosthesis may provide a good alternative, especially for young and active patients.
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| 4. |
- Hyldahl, H., et al.
(författare)
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All-polyethylene vs. metal-backed tibial component in total knee arthroplasty-a randomized RSA study comparing early fixation of horizontally and completely cemented tibial components: part 1. Horizontally cemented components: AP better fixated than MB
- 2005
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Ingår i: Acta Orthop. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 76:6, s. 769-77
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Controversy still exists as to whether to mount the tibial bearing on a metal baseplate or not. Furthermore, the tibial component can be either horizontally or completely cemented. We evaluated metal backing versus all-polyethylene using horizontal cementing technique. PATIENTS AND METHODS: We randomized 40 patients with knee arthrosis (40 knees) to 2 groups: cemented total knee arthroplasty (AGC, Biomet) using either all-polyethylene (AP) or metal-backed (MB) tibial components (n = 20 for each group). All tibial implants had a total thickness of 8 mm. We used proximal cement-ing, including only the horizontal part of the tibia with avoidance of the stem-bone interface. RESULTS: The positioning of the implants, as judged by the HKA angle, showed an average neutral alignment in both groups. Preoperatively and after 2 years, there was no statistically significant difference between the HSS scores in both groups (p = 0.6 and 0.4). After 2 years, the metal-backed components had rotated more around the longitudinal axis, median 0.5 degrees vs. 0.2 degrees (internal or external rotation, p = 0.002), and showed increased maximum total point motion, median 1.0 vs. 0.4 mm (maximum migration or MTPM, p = 0.003). INTERPRETATION: Our study indicates that better fixation can be obtained with the all-polyethylene design if proximally cemented thin components are used.
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| 5. |
- Hyldahl, H., et al.
(författare)
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All-polyethylene vs. metal-backed tibial component in total knee arthroplasty-a randomized RSA study comparing early fixation of horizontally and completely cemented tibial components: part 2. Completely cemented components: MB not superior to AP components
- 2005
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Ingår i: Acta Orthop. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 76:6, s. 778-84
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Uncertainty exists as to whether metal backing (MB) of the tibial component is better than an all-polyethylene component (AP). This is valid for both horizontally and completely cemented components. We evaluated completely cemented MB vs. AP (Part 2). PATIENTS AND METHODS: In a randomized study, 39 patients (40 knees) with knee arthrosis were operated with cemented low-conforming total knee arthroplasty (AGC, Biomet) with a tibial component of uniform thickness (8 mm), cemented both beneath the tibial tray and around the stem. 20 patients had an all-polyethylene (AP) tibial component and 20 patients had an identical but metal-backed (MB) tibial component. We used clinical examination and radiostereometric analysis (RSA) to evaluate the hypothesis that MB improves component fixation. Fixation was evaluated using RSA up to 2 years after surgery. Clinical assessment was performed preoperatively and after 2 years using the Hospital for Special Surgeons (HSS) score. RESULTS: We found no differences in micromotion, and no differences in clinical scores could be detected between the groups at any time point. INTERPRETATION: Our findings indicate that there was equal initial fixation of the AP and MB stemmed monobloc components when they were cemented beneath the tibial plateau and around the stem.
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| 6. |
- Olivecrona, Henrik, et al.
(författare)
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A new CT method for measuring cup orientation after total hip arthroplasty : A study of 10 patients
- 2004
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Ingår i: Acta Orthopaedica Scandinavica. - : Medical Journals Sweden AB. - 0001-6470. ; 75:3, s. 252-260
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Tidskriftsartikel (refereegranskat)abstract
- Background It is difficult to assess the orientation of the acetabular component on routine radiographs. We present a method for determining the spatial orientation of the acetabular component after total hip arthroplasty (THA) using computed tomography. Patients and methods Two CT-scans, 10 min apart, were obtained from each of 10 patients after THA. Using locally developed software, two independent examiners measured the orientation of the acetabular component in relation to the pelvis. The measurements were repeated after one week. To be independent of the patient position during scanning, the method involved two steps. Firstly, a 3D volumetric image of the pelvis was brought into a standard pelvic orientation, then the orientation of the acetabular component was measured. The orientation of the acetabular component was expressed as operative anteversion and inclination relative to an internal pelvic reference coordinate system. To evaluate precision, we compared measurements across pairs of CT volumes between observers and trials. Results Mean absolute interobserver angle error was 2.3degrees for anteversion (range 0-6.6degrees), and 1.1degrees for inclination (range 0-4.6degrees). For interobserver measurements, the precision, defined as one standard deviation, was 2.9degrees for anteversion, and 1.5degrees for inclination. A Student's West showed that the overall differences between the examiners, trials, and cases were not significant. Data were normally distributed and were not dependent on examiner or trial. Interpretation We conclude that the implant angles of the acetabular component in relation to the pelvis could be detected repeatedly using CT, independently of patient positioning.
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| 7. |
- Olivecrona, Henrik, et al.
(författare)
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Spatial component position in total hip arthroplasty - Accuracy and repeatability with a new CT method
- 2003
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 44:1, s. 84-91
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: 3D detection of centerpoints of prosthetic cup and head after total hip arthroplasty (THA) using CT. Material and Methods: Two CT examinations, 10 min apart, were obtained from each of 10 patients after THA. Two independent examiners placed landmarks in images of the prosthetic cup and head. All landmarking was repeated after 1 week. Centerpoints were calculated and compared. Results: Within volumes, all measurements of centerpoints of cup and head fell, with a 95% confidence, within one CT-voxel of any other measurement of the same object. Across two volumes, the mean error of distance between center of cup and prosthetic head was 1.4 mm (SD 0.73). Intra- and interobserver 95% accuracy limit was below 2 mm within and below 3 mm across volumes. No difference between intra- and interobserver measurements occurred. A formula for converting finite sets of point landmarks in the radiolucent tread of the cup to a centerpoint was stable. The percent difference of the landmark distances from a calculated spherical surface was within one CT-voxel. This data was normally distributed and not dependent on observer or trial. Conclusion: The true 3D position of the centers of cup and prosthetic head can be detected using CT. Spatial relationship between the components can be analyzed visually and numerically.
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| 8. |
- Olivecrona, Henrik, et al.
(författare)
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Stability of acetabular axis after total hip arthroplasty, repeatability using CT and a semiautomated program for volume fusion
- 2003
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 44:6, s. 653-661
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To validate a CT method for detecting changes in acetabular cup orientation after THA. Material and Methods: 26 CT examinations were obtained from a pelvic model with an uncemented acetabular cup. The model position was altered between acquisitions, but the cup axis angle vis-a-vis the pelvis was maintained. Data sets were combined into 37 pairs, each containing a unique positioning error. The pelvi in different examinations were fused, creating transformed volumes. Landmarks corresponding to the cup before and after fusion were placed interactively by two independent examiners. The orientation of the acetabular axis was calculated for each volume and compared across volumes. Results: Before fusion the mean angle error between the acetabular axes was 4.17degrees (SD +/- 1.95degrees). After fusion the mean angle error was 0.36degrees (SD +/- 0.17). The 95% repeatability limits were below 0.7degrees. There was no significant interobserver difference. Analysis of the cup landmarking pattern by condition numbers and individual landmark errors showed stability. Conclusion: Non-invasive fusion of CT volumes and a stable landmarking pattern for the acetabular cup outperforms routine plain radiography in detecting changes in the orientation of the acetabular axis over time. The method delivers both visual and numerical output and could be used in clinical practice.
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| 9. |
- Olivecrona, Lotta, et al.
(författare)
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Acetabular component migration in total hip arthroplasty using CT and a semiautomated program for volume merging
- 2002
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 43:5, s. 517-527
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To develop a non-invasive method for detection of acetabular cup migration after total hip arthroplasty (THA) with a higher degree of accuracy than routine plain radiography. Material and Methods: Two CT examinations, 10 min apart, were obtained from each of 10 patients that had undergone THA. Using an in-house developed semiautomated program for volume merging, the pelves in the two examinations were fused and the acetabular cup was visually and numerically evaluated to test the method's accuracy in detecting migration. Results: In the visual evaluation of the best match a 1-mm translation of the cup was detectable. The numerical evaluation, comparing landmarks placed in the images of the acetabular cup and the head of the femur component in the two examinations, showed the mean difference in orientation of acetabular axes to be 2.5degrees, the mean distance between centre of cup face to be 2.5 mm and the mean distance between centre of the head of the prosthetic femoral component to be 1 mm. Conclusion: This method has a significantly higher accuracy than routine plain radiography in detecting acetabular cup migration and could be used in clinical practice. It gives both a visual and a numerical correlate to migration.
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| 10. |
- Olivecrona, Lotta, et al.
(författare)
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Standard orientation of the pelvis : Validation on a model and ten patients
- 2005
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Ingår i: Acta Radiologica. - London, UK : Informa Healthcare. - 0284-1851 .- 1600-0455. ; 46:1, s. 74-82
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To validate an image post-processing method for re-orienting the pelvis in CT volumes to a standardized orientation in a model and in 10 patients. Material and Methods: Twenty-four CT volumes of a pelvic model and 10 pairs of postoperative total hip arthroplasty (THA) patient CT scans were rotated to a defined pelvic standard orientation and the rotation was recorded. For precision, a test-retest procedure was used. For accuracy, three exactly represented coordinate points were used. For clinical application, the standard orientation was used for calculating the direction of acetabular cup migration from a previous model study. Results: Precision of pelvic standard orientation, calculated as maximal directional error, was better than 1degrees in the model study and better than 1.5degrees in the patient study. Accuracy, expressed as angle between ideal and measured coordinate axes, was 0.1degrees for x, y, z axes. No measurable systematic errors were found. When applied to acetabular cup migration in the model, standardization of pelvic orientation had no significant effect on the measurements. Conclusion: Reorienting the pelvis during image post-processing was shown to be accurate. It enables measurements relative to the pelvis and minimizes the dependency of patient positioning.
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| 11. |
- Sandgren, Buster, et al.
(författare)
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Computed Tomography vs. Digital Radiography Assessment for Detection of Osteolysis in Asymptomatic Patients With Uncemented Cups: A Proposal for a New Classification System Based on Computer Tomography.
- 2013
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Ingår i: The Journal of arthroplasty. - : Elsevier BV. - 1532-8406 .- 0883-5403. ; 28:9, s. 1608-1613
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Tidskriftsartikel (refereegranskat)abstract
- Digital radiographic images in the anterior-posterior and lateral view have been gold standard for evaluation of peri-acetabular osteolysis for patients with an uncemented hip replacement. We compared digital radiographic images and computer tomography in detection of peri-acetabular osteolysis and devised a classification system based on computer tomography. Digital radiographs were compared with computer tomography on 206 hips, with a mean follow up 10years after surgery. The patients had no clinical signs of osteolysis and none were planned for revision surgery. On digital radiographs, 192 cases had no osteolysis and only 14 cases had osteolysis. When using computer tomography there were 184 cases showing small or large osteolysis and only 22 patients had no osteolysis. A classification system for peri-acetabular osteolysis is proposed based on computer tomography that is easy to use on standard follow up evaluation.
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| 12. |
- Essving, Per, 1960-
(författare)
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Local infiltration analgesia in knee arthroplasty
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Local infiltration analgesia (LIA) is a new technique for postoperative pain management following knee arthroplasty. LIA involves a long-acting local anesthetic (ropivacaine), a non-steroid anti-inflammatory drug (ketorolac) and epinephrine infiltrated into the knee joint during surgery and injected postoperatively via a catheter.In the first two studies, LIA was compared with placebo in unicompartmental (I) and total (II) knee arthroplasty. Postoperative pain levels, morphine consumption and the incidence of side effects were lower in the LIA groups. In addition, we found a shorter length of hospital stay in the LIA group following unicompartmental knee arthroplasty compared with placebo (I), while the time to home readiness was shorter in the LIA group following total knee arthroplasty (II). In this study, we found that the unbound venous blood concentration of ropivacaine was below systemic toxic blood concentrations in a sub-group of patients.In the third study, LIA was compared with intrathecal morphine for postoperative pain relief following total knee arthroplasty (III). Pain scores and morphine consumption were lower, length of hospital stay was shorter and patient satisfaction was higher in the LIA group.In the final study, we investigated the effect of minimally invasive surgery (MIS) compared with conventional surgery in unicompartmental knee arthroplasty (IV). Both groups received LIA. We found no statistically significant differences in postoperative pain, morphine consumption, knee function, home readiness, hospital stay or patient satisfaction.In conclusion, LIA provided better postoperative pain relief and earlier mobilization than placebo, both in unicompartmental and total knee arthroplasty. When compared to intrathecal morphine, LIA also resulted in improved postoperative pain relief and earlier mobilization. Minimally invasive surgery did not improve outcomes after unicompartmental knee arthroplasty, when both groups received LIA.
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| 13. |
- Goldvasser, Dov, et al.
(författare)
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In vivo and ex vivo measurement of polyethylene wear in total hip arthroplasty
- 2014
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Ingår i: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 85:3, s. 271-275
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Tidskriftsartikel (refereegranskat)abstract
- Background - Determination of the amount of wear in a polyethylene liner following total hip arthroplasty (THA) is important for both the clinical care of individual patients and the development of new types of liners. Patients and methods - We measured in vivo wear of the polyethylene liner using computed tomography (CT) (obtained in the course of regular clinical care) and compared it to coordinate-measuring machine (CMM) readings. Also, changes in liner thickness of the same retrieved polyethylene liner were measured using a micrometer, and were compared to CT and CMM measurements. The distance between the centers of the acetabular cup and femoral head component was measured in 3D CT, using a semi-automatic analysis method. CMM readings were performed on each acetabular liner and data were analyzed using 3D computer-aided design software. Micrometer readings compared the thickest and thinnest regions of the liner. We analyzed 10 THA CTs and retrievals that met minimal requirements for CT slice thickness and explanted cup condition. Results - For the 10 cups, the mean difference between the CT readings and the CMM readings was -0.09 (-0.38 to 0.20) mm. This difference was not statistically significant (p = 0.6). Between CT and micrometer, the mean difference was 0.11 (-0.33 to 0.55) mm. This difference was not statistically significant (p = 0.6). Interpretation - Our results show that CT imaging is ready to be used as a tool in clinical wear measurement of polyethylene liners used in THA.
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| 14. |
- Lazarinis, Stergios, 1971-
(författare)
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Form and Finish of Implants in Uncemented Hip Arthroplasty : Effects of Different Shapes and Surface Treatments on Implant Stability
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The design of an uncemented hip arthroplasty implant affects its long-term survival. Characteristics such as the form and the finish of the implant are crucial in order to achieve the best possible conditions for long-term implant survival. In this thesis we hypothesized that different shapes of stems and cups used in primary and revision total hip arthroplasty (THA), and their finish with hydroxyapatite (HA) coating affect implant stability and thus long-term survival.In 2 prospective cohort studies the clinical outcome, the stability measured with radiostereometric analysis (RSA), and the periprosthetic changes in bone mineral density (BMD) measured with dual-energy x-ray absorptiometry (DXA) were investigated in 2 uncemented THA implants – the CFP stem and the TOP cup. In 3 register studies the effect of HA coating on uncemented THA implants used in primary and revision arthroplasty was investigated.Both implants investigated in the prospective cohort studies showed an excellent short-term clinical outcome with good primary stability, but neither their novel form nor the finish with HA protected the implants from the proximal periprosthetic demineralization that usually occurs around other uncemented THA implants.The register studies revealed that HA coating on cups used in primary and revision THA is a risk factor for subsequent revision of the implant. The use of HA coating on the stem in primary THA did not affect long-term survival. Additionally, the shape of an implant plays a crucial role for implant stability and survival.In conclusion, this thesis highlights that the finish of implants with HA coating does not prevent periprosthetic proximal femoral bone loss and can even enhance the risk of revision of both primary and secondary cups. Importantly, the shape of uncemented THA implants affect their stability, showing that the implant form is a crucial factor for the long-term survival.
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| 15. |
- Lundblad, Henrik, et al.
(författare)
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Can Na18F PET/CT Be Used to Study Bone Remodeling in the Tibia When Patients Are Being Treated with a Taylor Spatial Frame?
- 2014
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Ingår i: Scientific World Journal. - : Hindawi Publishing Corporation. - 1537-744X .- 2356-6140. ; 2014, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Monitoring and quantifying bone remodeling are of interest, for example, in correction osteotomies, delayed fracture healing pseudarthrosis, bone lengthening, and other instances. Seven patients who had operations to attach an Ilizarov-derived Taylor Spatial Frame to the tibia gave informed consent. Each patient was examined by (NaF)-F-18 PET/CT twice, at approximately six weeks and three months after the operation. A validated software tool was used for the following processing steps. The first and second CT volumes were aligned in 3D and the respective PET volumes were aligned accordingly. In the first PET volume spherical volumes of interest (VOIs) were delineated for the crural fracture and normal bone and transferred to the second PET volume for SUVmax evaluation. This method potentially provides clinical insight into questions such as, when has the bone remodeling progressed well enough to safely remove the TSF? and when is intervention required, in a timelier manner than current methods? For example, in two patients who completed treatment, the SUVmax between the first and second PET/CT examination decreased by 42% and 13%, respectively. Further studies in a larger patient population are needed to verify these preliminary results by correlating regional (NaF)-F-18 PET measurements to clinical and radiological findings.
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| 16. |
- Lundblad, Henrik, et al.
(författare)
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Can Na18F PET/CT bone scans help when deciding if early intervention is needed in patients being treated with a TSF attached to the tibia : insights from 41 patients.
- 2020
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Ingår i: European Journal of Orthopaedic Surgery & Traumatology. - : Springer Nature. - 1633-8065 .- 1432-1068. ; 31:2, s. 349-364
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To demonstrate the usefulness of positron emission tomography (PET)/computed tomography (CT) bone scans for gaining insight into healing bone status earlier than CT or X-ray alone.METHODS: Forty-one prospective patients being treated with a Taylor Spatial Frame were recruited. We registered data obtained from successive static CT scans for each patient, to align the broken bone. Radionuclide uptake was calculated over a spherical volume of interest (VOI). For all voxels in the VOI, histograms and cumulative distribution functions of the CT and PET data were used to assess the type and progress of new bone growth and radionuclide uptake. The radionuclide uptake difference per day between the PET/CT scans was displayed in a scatter plot. Superimposing CT and PET slice data and observing the spatiotemporal uptake of 18F- in the region of healing bone by a time-sequenced movie allowed qualitative evaluation.RESULTS: Numerical evaluation, particularly the shape and distribution of Hounsfield Units and radionuclide uptake in the graphs, combined with visual evaluation and the movies enabled the identification of six patients needing intervention as well as those not requiring intervention. Every revised patient proceeded to a successful treatment conclusion.CONCLUSION: Numerical and visual evaluation based on all the voxels in the VOI may aid the orthopedic surgeon to assess a patient's progression to recovery. By identifying slow or insufficient progress at an early stage and observing the uptake of 18F- in specific regions of bone, it might be possible to shorten the recovery time and avoid unnecessary late complications.
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| 17. |
- Lundblad, Henrik, et al.
(författare)
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Can Spatiotemporal Fluoride (18F-ˆ’) Uptake be Used to Assess Bone Formation in the Tibia? : A Longitudinal Study Using PET/CT
- 2017
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Ingår i: Clinical Orthopaedics and Related Research. - : Springer. - 0009-921X .- 1528-1132. ; 475:5, s. 1486-1498
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Tidskriftsartikel (refereegranskat)abstract
- When a bone is broken for any reason, it is important for the orthopaedic surgeon to know how bone healing is progressing. There has been resurgence in the use of the fluoride (18F-ˆ’) ion to evaluate various bone conditions. This has been made possible by availability of positron emission tomography (PET)/CT hybrid scanners together with cyclotrons. Absorbed on the bone surface from blood flow, 18F-ˆ’ attaches to the osteoblasts in cancellous bone and acts as a pharmacokinetic agent, which reflects the local physiologic activity of bone. This is important because it shows bone formation indicating that the bone is healing or no bone formation indicating no healing. As 18F-ˆ’ is extracted from blood in proportion to blood flow and bone formation, it thus enables determination of bone healing progress.
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| 18. |
- Lundblad, Henrik, et al.
(författare)
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Using PET/CT Bone Scan Dynamic Data to Evaluate Tibia Remodeling When a Taylor Spatial Frame Is Used : Short and Longer Term Differences
- 2015
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Ingår i: BioMed Research International. - : Hindawi Publishing Corporation. - 2314-6133 .- 2314-6141. ; 2015, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Eighteen consecutive patients, treated with a Taylor Spatial Frame for complex tibia conditions, gave their informed consentto undergo Na18F− PET/CT bone scans. We present a Patlak-like analysis utilizing an approximated blood time-activity curveeliminating the need for blood aliquots. Additionally, standardized uptake values (SUV) derived from dynamic acquisitions werecompared to this Patlak-like approach. Spherical volumes of interest (VOIs) were drawn to include broken bone, other (normal)bone, and muscle. The SUV?(?) (? = max, mean) and a series of slopes were computed as (SUV?(??) − SUV?(??))/(?? − ??), forpairs of time values ?? and ??. A Patlak-like analysis was performed for the same time values by computing ((VOI?(??)/VOI?(??)) −(VOI?(??)/VOI?(??)))/(??−??), where p = broken bone, other bone, andmuscle and e = expected activity in aVOI. Paired comparisonsbetween Patlak-like and SUV? slopes showed good agreement by both linear regression and correlation coefficient analysis(? = 84%, ?? = 78%-SUVmax, ? = 92%, and ?? = 91%-SUVmean), suggesting static scans could substitute for dynamic studies.Patlak-like slope differences of 0.1 min−1 or greater between examinations and SUVmax differences of ∼5 usually indicated goodremodeling progress, while negative Patlak-like slope differences of −0.06 min−1 usually indicated poor remodeling progress in thiscohort.
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| 19. |
- Maguire Jr., Gerald Q., et al.
(författare)
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A New Automated Way to Measure Polyethylene Wear in THA Using a High Resolution CT Scanner : Method and Analysis
- 2014
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Ingår i: Scientific World Journal. - : Hindawi Limited. - 1537-744X .- 2356-6140. ; 2014, s. 528407-
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Tidskriftsartikel (refereegranskat)abstract
- As the most advantageous total hip arthroplasty (THA) operation is the first, timely replacement of only the liner is socially and economically important because the utilization of THA is increasing as younger and more active patients are receiving implants and they are living longer. Automatic algorithms were developed to infer liner wear by estimating the separation between the acetabular cup and femoral component head given a computed tomography (CT) volume. Two series of CT volumes of a hip phantom were acquired with the femoral component head placed at 14 different positions relative to the acetabular cup. The mean and standard deviation (SD) of the diameter of the acetabular cup and femoral component head, in addition to the range of error in the expected wear values and the repeatability of all the measurements, were calculated. The algorithms resulted in a mean (+/- SD) for the diameter of the acetabular cup of 54.21 (+/- 0.011) mm and for the femoral component head of 22.09 (+/- 0.02) mm. The wear error was +/- 0.1 mm and the repeatability was 0.077 mm. This approach is applicable clinically as it utilizes readily available computed tomography imaging systems and requires only five minutes of human interaction.
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| 20. |
- Mostroem, Eva Bengtsson, et al.
(författare)
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Pre- and postcontrast T1 and T2 mapping of patellar cartilage in young adults with recurrent patellar dislocation
- 2015
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Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 1522-2594 .- 0740-3194. ; 74:5, s. 1363-1369
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Tidskriftsartikel (refereegranskat)abstract
- PurposeTo examine the cartilage quality in young adults with recurrent patellar dislocation in childhood using different magnetic resonance imaging parameters. MethodsSixteen young adults with unilateral recurrent patellar dislocation were investigated 5 y (mean, 8.5 y) after the first dislocation. Pre- and postcontrast T1 and precontrast T2 relaxation times were analyzed in four superficial and four deep patellar cartilage regions of both knees. Two hours after intravenous injection of 0.2 mM/kg Gd-DTPA(2-), postcontrast T1 [T1(Gd)] and R1 [1/T1 (precontrast)-1/T1 (postcontrast)] were analyzed in the regions. Muscle performance and patient-reported outcome were evaluated. ResultsWhen comparing the injured side with the noninjured side, differences were seen in the superficial half but not the deep half of the cartilage. T1(Gd) was shorter in the central part, whereas T2 was shorter in the periphery of the patellar cartilage (P<0.05). R1 demonstrated similar differences between healthy and diseased cartilage as T1(Gd) alone. The knee function was not correlated to the degenerative changes. ConclusionThe short T1(Gd) centrally indicates degenerative cartilage changes consistent with loss of glycosaminoglycans. Precontrast and R1 calculations may be excluded in clinical dGEMRIC, which simplifies the procedure. A decrease in T2 may be a very early sign of joint pathology but warrants further investigation. Magn Reson Med 74:1363-1369, 2015. (c) 2014 Wiley Periodicals, Inc.
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| 21. |
- Olivecrona, Henrik, et al.
(författare)
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A CT method for following patients with both prosthetic replacement and implanted tantalum beads : preliminary analysis with a pelvic model and in seven patients
- 2016
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Ingår i: Journal of Orthopaedic Surgery and Research. - : BioMed Central (BMC). - 1749-799X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Radiostereometric analysis (RSA) is often used for evaluating implanted devices over time. Following patients who have had tantalum beads implanted as markers in conjunction with joint replacements is important for longitudinal evaluation of these patients and for those with similar implants. As doing traditional RSA imaging is exacting and limited to specialized centers, it is important to consider alternative techniques for this ongoing evaluation. This paper studies the use of computed tomography (CT) to evaluate over time tantalum beads which have been implanted as markers. Methods: The project uses both a hip model implanted with tantalum beads, acquired in several orientations, at two different CT energy levels, and a cohort of seven patients. The model was evaluated twice by the same observer with a 1-week interval. All CT volumes were analyzed using a semi-automated 3D volume fusion (spatial registration) tool which provides landmark-based fusion of two volumes, registering a target volume with a reference volume using a rigid body 3D algorithm. The mean registration errors as well as the accuracy and repeatability of the method were evaluated. Results: The mean registration error, maximum value of repeatability, and accuracy for the relative movement in the model were 0.16 mm, 0.02 degrees and 0.1 mm, and 0.36 degrees and 0.13 mm for 120 kVp and 0.21 mm, 0.04 degrees and 0.01 mm, and 0.39 degrees and 0.12 mm for 100 kVp. For the patients, the mean registration errors per patient ranged from 0.08 to 0.35 mm. These results are comparable to those in typical clinical RSA trials. This technique successfully evaluated two patients who would have been lost from the cohort if only RSA were used. Conclusions: The proposed technique can be used to evaluate patients with tantalum beads over time without the need for stereoradiographs. Further, the effective dose associated with CT is decreasing.
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| 22. |
- Olivecrona, Henrik, et al.
(författare)
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A new technique for diagnosis of acetabular cup loosening using computed tomography - Preliminary experience in 10 patients
- 2008
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Ingår i: Acta Orthopaedica. - New York, NY, USA : Informa Healthcare. - 1745-3674 .- 1745-3682. ; 79:3, s. 346-353
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose: Considerable migration of the acetabular cup is required for diagnosis of loosening by conventional radiography. We have developed a new clinically applicable method for assessment of cup loosening using computed tomography (CT). Patients and methods 10 patients scheduled for revision hip replacement due to suspected wear or loosening were scanned twice with CT under torsion loading of the prosthesis. Two independent examiners assessed each patient with respect to motion of the acetabular cup relative to the pelvis using CT volume registration. The CT measurements were compared to findings at revision surgery. Results The method was applicable in 8 of the 10 patients. 1 patient had a severe tremor. In 1 patient, surgery revealed that the hip was ankylotic due to massive ectopic bone formation. This left 8 patients that could be evaluated. 4 cups were loose at surgery, and 3 of these cups could be seen to be mobile by CT. 4 cups that were stable on revision were accurately diagnosed as not being mobile by CT. Movements of less than 1 millimeter between bone and prosthesis could not be distinguished from errors in CT acquisition and volume registration. There was good agreement between the two observers. Interpretation Movement of loose acetabular cups during torsion loading could be detected using CT volume registration. It was sensitive to cup movement in 3 out of 4 cases of loose cups. The method was specific and yielded no false positive results.
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| 23. |
- Olivecrona, Lotta, et al.
(författare)
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Assessing wear of the acetabular cup using computed tomography : an ex vivo study
- 2005
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Ingår i: Acta Radiologica. - London, UK : Informa Healthcare. - 0284-1851 .- 1600-0455. ; 46:8, s. 852-857
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To validate a clinically useful method for measuring acetabular cup wear using computed tomography (CT). Material and Methods: Eight uncemented acetabular cups were scanned twice ex vivo using CT. The linear penetration depth of the femoral component head into the cup and the thickness of the remaining polyethylene liner were measured in the CT volumes using dedicated software. Two independent examiners twice assessed each volume. The CT measurements were compared to direct measurements using a coordinate measuring device and micrometer measurements. Results: Accuracy of wear measurements expressed as penetration depth was +/- 0.6 and +/- 1.0 mm for the two examiners, respectively, with no significant differences between examiners, trials, and CT scans. Accuracy of measurements of remaining polyethylene was +/- 1.3 and +/- 1.0 mm, respectively, for the two examiners. Systematic differences between examiners were found, but no significant differences between trials and CT scans. These differences were due to different interpretations of metal artifacts in the volumes. Conclusion: The proposed CT method for evaluating wear as head penetration depth allows for reliable wear detection at a clinically relevant level. Measurements of remaining polyethylene on CT volumes are not as reliable as wear measurements owing to metal artifacts.
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| 24. |
- Olivecrona, Lotta, et al.
(författare)
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Model studies on acetabular component migration in total hip arthroplasty using CT and a semiautomated program for volume merging
- 2003
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 44:4, s. 419-429
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Validation of a non-invasive CT method for detection of acetabular cup migration after total hip arthroplasty in a phantom study. Material and Methods: 26 CT examinations were obtained of a pelvic model while altering the position of the acetabular cup. Using a previously described program for volume merging, the pelvi in different examinations were fused and the 3D alterations of the position of the acetabular cup were evaluated visually and numerically and correlated to direct measurements on the model. Results: Visually, two independent examiners differentiated between 0, 1 and 2 to 3 mm migration with 100% specificity and sensitivity. Numerically, the mean error over all cases between model and CT measurements was 0.04 mm (SD +/- 0.33). The mean absolute error between model and CT data was 0.26 mm (SD +/- 0.19). Intra- and interobserver 95% accuracy and repeatability limits were below 0.5/0.7 mm, respectively. No significant interobserver difference occurred. The data were normally distributed and not dependent on observer. Conclusion: The accuracy of this non-invasive method out-performs routine plain radiography. The method gives both visual and numerical correlates to migration and can be used in clinical practice.
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| 25. |
- Sayed-Noor, Arkan Sam, 1973-
(författare)
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Greater trochanteric pain after total hip arthroplasty : incidence, clinical outcome, associated factors, tenderness evaluation with algometer and a new surgical treatment
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Greater trochanteric pain (GTP) is a regional pain syndrome characterized by lateral hip pain and tenderness. Its incidence after total hip arthroplasty (THA) is variable. Bursal inflammation, degenerative changes of the attachment of the gluteal muscles, direct operative trauma and biomechanical disturbance of the operated hip have been discussed as being related to GTP. The diagnosis is purely clinical because radiological and laboratory investigations show no definite pathology. Although most treatment modalities are conservative, some patients may develop refractory complaints leading to surgical intervention. In study I we studied the incidence of GTP in 172 consecutive patients who underwent THA during 2002 at Sundsvall Hospital. Patients with GTP (n=21, incidence 12%) were matched with controls from the same cohort. The THA outcome was assessed using the Western Ontario and McMaster Universities Arthrosis (WOMAC) Index. Trochanteric tenderness was studied using an electronic pressure algometer. We found an association between the occurrence of GTP and postoperative uncorrected lengthening of the operated limb of ≥ one centimetre. The WOMAC index revealed a reduction of the clinical outcome in the GTP group. In Study II we tested the value of using an algometer in the diagnosis of GTP after THA. We measured the pressure-pain threshold (PPT) over the greater trochanter and ilio-tibial band in 18 patients and 18 matched controls. Both groups were evaluated using the visual analogue scale (VAS). We found the algometer to have a good predictive validity and reproducibility. However, there was large inter-individual variability across subjects. The PPT ratio of 0.8 (affected vs. unaffected side) can be used as a cutoff ratio to establish GTP. There was no correlation between PPT measurements and VAS. Because of a low positive predictive value and large inter-individual variability, the pressure algometer has a limited value as a screening tool. In study III we proposed a new surgical treatment for refractory GTP after THA consisting of distal lengthening of the ilio-tibial band (ITB) by Z-plasty under local anaesthesia. This method was used in 12 women between March 2004 and June 2006. The patients were followed up by phone interview 3-4 months postoperatively and by an EQ-5D questionnaire and clinical examination including evaluation with the algometer at 1-3 years postoperatively. We found that the patients‘ quality of life was markedly improved following the operation (EQ-5D = 0.26 preoperatively vs. 0.67 postoperatively; p <0.005). There were no postoperative complications. In study IV we evaluated the accuracy of a commonly used clinical method of LLD measurement (anterior superior iliac spine-medial malleolus) by comparing it to a reliable radiological method (tear drop-lesser trochanter) in 139 patients before and after THA. We found the correlation between the clinical and radiological methods to be weak preoperatively (r=0.21, ICC= 0.33) while the correlation was moderate postoperatively (r= 0.45, ICC=0.62). It is therefore recommended that the radiological method be used to measure leg length discrepancy in patients who undergo THA.
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| 26. |
- 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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| 27. |
- 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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| 28. |
- 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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| 29. |
- Weidenhielm, Lars, et al.
(författare)
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Prosthetic liner wear in total hip replacement : a longitudinal 13-year study with computed tomography.
- 2018
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Ingår i: Skeletal Radiology. - : Springer. - 0364-2348 .- 1432-2161. ; 47:6, s. 883-887
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Tidskriftsartikel (refereegranskat)abstract
- This case report follows a woman who had a total hip replacement in 1992 when she was 45 years old. Six serial computed tomography (CT) examinations over a period of 13 years provided information that allowed her revision surgery to be limited to liner replacement as opposed to replacement of the entire prosthesis. Additionally, they provided data that ruled out the presence of osteolysis and indeed none was found at surgery. In 2004, when the first CT was performed, the 3D distance the femoral head had penetrated into the cup was determined to be 2.6 mm. By 2017, femoral head penetration had progressed to 5.0 mm. The extracted liner showed wear at the thinnest part to be 5.5 mm, as measured with a micrometer. The use of modern CT techniques can identify problems, while still correctable without major surgery. Furthermore, the ability of CT to assess the direction of wear revealed that the liner wear changed from the cranial to dorsal direction.
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