| 1. |
- Dahlberg, Leif, et al.
(författare)
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Proteoglycan fragments in joint fluid : Influence of arthrosis and inflammation
- 1992
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Ingår i: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 0001-6470. ; 63:4, s. 417-423
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Tidskriftsartikel (refereegranskat)abstract
- We determined the concentration of proteoglycan fragments in knee joint fluid collected from knee-ligament injured patients more than 6 months after the trauma and from patients with acute pyrophosphate arthritis and arthrosis or with arthrosis only. Injured patients with normal or only mildly altered cartilage at arthroscopy and with normal radiographs, had twice the average concentration of healthy volunteers. Other injured patients with advanced, radiographic signs of arthrosis, had synovial fluid proteoglycan fragment concentrations within the range of healthy volunteers. Patients with pyrophosphate arthritis had the highest concentrations, substantially increased compared with both arthrosis patients, with or without knee injury and healthy volunteers. Likewise, there was an inverse relation between the degree of arthrosis and the concentration of proteoglycan fragments in the joint fluid in patients with pyrophosphate arthritis and arthrosis or with arthrosis only. We conclude that synovial fluid levels of proteoglycan fragments are influenced by the mass of cartilage matrix remaining in the joint, the inflammatory activity in the joint, and the metabolic activity of the cartilage cells.
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| 2. |
- Lohmander, Stefan, et al.
(författare)
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Increased levels of proteoglycan fragments in knee joint fluid after injury
- 1989
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Ingår i: Arthritis and Rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 32:11, s. 1434-1442
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Tidskriftsartikel (refereegranskat)abstract
- We measured the levels of cartilage proteoglycan (PG) fragments in knee joint synovial fluid obtained from patients with previous trauma of the knee, early gonarthrosis, or pyrophosphate synovitis, and in age-matched control subjects. During the initial 3-4 weeks after rupture of the anterior cruciate ligament or the meniscus (confirmed by arthroscopy), markedly increased PG fragment levels were found. At later times after trauma (up to 4 years), many of these patients still had significantly elevated levels of cartilage PG fragments in the joint fluid. In a group of older patients with gonarthrosis, these levels were only moderately elevated, while in patients with acute pseudogout, greatly increased levels were observed. Although longitudinal studies are needed to validate the significance, PG fragments in joint fluid may be a marker for early posttraumatic arthrosis.
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| 3. |
- Almquist, Per Otto, et al.
(författare)
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Evaluation of an external device measuring knee joint rotation: an in vivo study with simultaneous Roentgen stereometric analysis.
- 2002
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Ingår i: Journal of Orthopaedic Research. - 1554-527X. ; 20:3, s. 427-432
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Tidskriftsartikel (refereegranskat)abstract
- An external device ("rottometer") specially designed to measure knee joint rotation was developed and evaluated with respect to its validity. Simultaneous measurements were made with the rottometer and Roentgen stereometric analysis (RSA) in five patients with implanted tantalum markers in the tibia and femur. Measurements of internal and external rotation were made at 90 degrees and 60 degrees of knee flexion using 3, 6 and 9 N m torques. The coefficients of determination (r2) between the results obtained with the rottometer and RSA were around 0.9 for the total rotation. The rottometer consistently overestimated the rotation by about 100% and this systematic error was most constant at 90 degrees flexion for the different torques. The magnitude of this error from soft tissue deformation as well as the rotatory movements in the hip, foot and ankle joints must be considered when using external devices to measure knee rotation in clinical studies. The most accurate registrations were found in 90 degrees flexion with 9 N m force (r2 = 0.94).
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| 4. |
- Barker, D S, et al.
(författare)
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A circumferentially flanged tibial tray minimizes bone-tray shear micromotion.
- 2005
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Ingår i: Proceedings of the Institution of Mechanical Engineers. Part H: Journal of Engineering in Medicine. - 0954-4119. ; 219:6, s. 449-456
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Tidskriftsartikel (refereegranskat)abstract
- Aseptic loosening of the tibial component is the major complication of total knee arthroplasty There is an association between early excessive shear micromotion between the bone and the tray of the tibial component and late aseptic loosening. Using non-linear finite element analysis, whether a tibial tray with a circumferentially flanged rim and a mating cut in the proximal tibia could minimize bone-tray shear micromotion was considered. fifteen competing tray designs with various degrees of flange curvature were assessed with the aim of minimizing bone-tray shear micromotion. A trade-off was found between reducing micromotion and increasing peripheral cancellous bone stresses. It was found that, within the limitations of the study, there was a theoretical design that could virtually eliminate micromotion due to axial loads, with minimal bone removal and without the use of screws or pegs.
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| 5. |
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| 6. |
- Bernfort, Lars, et al.
(författare)
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Individualized metal implants for focal cartilage lesions in the knee can be cost-effective: A simulation on 47-year-old in a Swedish setting
- 2023
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Ingår i: JOURNAL OF ISAKOS JOINT DISORDERS & ORTHOPAEDIC SPORTS MEDICINE. - : ELSEVIER. - 2059-7754. ; 8:3, s. 197-203
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: In the aging population, the knee is the joint most commonly causing impaired function and incapacity. While definite treatment by prosthetic replacement is often performed late, symptomatic knee cartilage lesions cause much suffering also in younger ages. Early intervention could, therefore, be instituted at an early stage to the benefit of both patients and society. Small, metal surface, resurfacing implants have been tested with promising results. A system that features patient-specific implants and surgical instruments shows good clinical results and favorable survival rates. This study aims to assess the cost utility of this metal device compared with microfracture (MFX), being the standard procedure in Sweden. Methods: We constructed a simulation model in Excel. In the model, a cohort of 47-year-old patients (which is the mean age of patients treated with the metal implant) with symptomatic knee cartilage lesions received either MFX or metal implantation. Outcomes for the cohort were simulated over 40 years, such as in a previously published model based on MFX, and sensitivity analyses (deterministic and probabilistic) of the results were undertaken. Data on transition probabilities, costs, and quality of life were taken from clinical data, published literature, and official price lists. Only direct medical costs were included. Results: Results from the analysis showed that the metal device is a cost-effective treatment strategy compared with MFX. The incremental cost-effectiveness ratio (ICER) reached acceptable levels at similar to 5 years postoperatively. Over the full-time horizon of 40 years, the metal device was cost saving with concomitant gains in quality-adjusted life years (QALYs), translating to a dominant treatment strategy. Results were robust according to sensitivity analysis with the initial success rate of up to three years for both metal and MFX having the largest impact. Conclusions: A metal implant may be a cost-effective treatment alternative for patients in their 40s when compared to MFX in a Swedish setting.
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| 7. |
- Bottner, F, et al.
(författare)
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Implant migration after early weightbearing in cementless hip replacement
- 2005
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Ingår i: Clinical Orthopaedics and Related Research. - 0009-921X .- 1528-1132. ; :436, s. 132-137
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Tidskriftsartikel (refereegranskat)abstract
- Twenty-nine patients (five women and 24 men) with an average age of 47 years (range, 24-59 years) had 37 total hip arthroplasties using a hydroxyapatite-coated double-wedge press-fit femoral component. All patients had a Type A bone quality. Patients were either mobilized with weightbearing as tolerated or toe-touch weightbearing for 6 weeks postoperatively. After 6 weeks all patients were advanced to weightbearing as tolerated. Radiostereometric analysis radiographs were taken at 3 days, 6 weeks, and 6 months postoperatively to measure migration of the femoral component. Radiostereometric analysis revealed no difference in stem migration between the two groups as defined by maximal total point migration. There was a difference in the vertical (proximal-distal) migration within the first 6 weeks between groups (0.81 mm versus 0.13 mm), but not afterwards (0.17 mm versus 0.18 mm). Continuous migration after 6 weeks was observed in three patients from each group. There was no loosening in either group within a 2-year followup. Weightbearing as tolerated is recommended for young patients with excellent bone quality after cementless total hip arthroplasty with a double-wedge press-fit femoral component. Level of Evidence: Diagnostic study, Level I (testing of previously developed diagnostic criteria in series of consecutive patients-with previously applied reference gold standard). See the Guidelines for Authors for a complete description of levels of evidence.
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| 8. |
- de Boniface, J., et al.
(författare)
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The generalisability of randomised clinical trials: an interim external validity analysis of the ongoing SENOMAC trial in sentinel lymph node-positive breast cancer
- 2020
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Ingår i: Breast Cancer Research and Treatment. - : Springer Science and Business Media LLC. - 0167-6806 .- 1573-7217. ; 180:1, s. 167-176
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Tidskriftsartikel (refereegranskat)abstract
- Purpose None of the key randomised trials on the omission of axillary lymph node dissection (ALND) in sentinel lymph-positive breast cancer have reported external validity, even though results indicate selection bias. Our aim was to assess the external validity of the ongoing randomised SENOMAC trial by comparing characteristics of Swedish SENOMAC trial participants with non-included eligible patients registered in the Swedish National Breast Cancer Register (NKBC). Methods In the ongoing non-inferiority European SENOMAC trial, clinically node-negative cT1-T3 breast cancer patients with up to two sentinel lymph node macrometastases are randomised to undergo completion ALND or not. Both breast-conserving surgery and mastectomy are eligible interventions. Data from NKBC were extracted for the years 2016 and 2017, and patient and tumour characteristics compared with Swedish trial participants from the same years. Results Overall, 306 NKBC cases from non-participating and 847 NKBC cases from participating sites (excluding SENOMAC participants) were compared with 463 SENOMAC trial participants. Patients belonging to the middle age groups (p = 0.015), with smaller tumours (p = 0.013) treated by breast-conserving therapy (50.3 versus 47.1 versus 65.2%, p < 0.001) and less nodal tumour burden (only 1 macrometastasis in 78.8 versus 79.9 versus 87.3%, p = 0.001) were over-represented in the trial population. Time trends indicated, however, that differences may be mitigated over time. Conclusions This interim external validity analysis specifically addresses selection mechanisms during an ongoing trial, potentially increasing generalisability by the time full accrual is reached. Similar validity checks should be an integral part of prospective clinical trials. Trial registration: NCT 02240472, retrospective registration date September 14, 2015 after trial initiation on January 31, 2015
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| 9. |
- Dunbar, M J, et al.
(författare)
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Appropriate questionnaires for knee arthroplasty. Results of a survey of 3600 patients from The Swedish Knee Arthroplasty Registry
- 2001
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Ingår i: Journal of Bone and Joint Surgery: British Volume. - 2044-5377. ; 83:3, s. 339-344
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Tidskriftsartikel (refereegranskat)abstract
- The Swedish Knee Arthroplasty Registry (SKAR) has recorded knee arthroplasties prospectively in Sweden since 1975. The only outcome measure available to date has been revision status. While questionnaires on health outcome may function as more comprehensive endpoints, it is unclear which are the most appropriate. We tested various outcome questionnaires in order to determine which is the best for patients who have had knee arthroplasty as applied in a cross-sectional, discriminative, postal survey. Four general health questionnaires (NHP, SF-12, SF-36 and SIP) and three disease/site-specific questionnaires (Lequesne, Oxford-12, and WOMAC) were tested on 3600 patients randomly selected from the SKAR. Differences were found between questionnaires in response rate, time required for completion, the need for assistance, the efficiency of completion, the validity of the content and the reliability. The mean overall ranks for each questionnaire were generated. The SF-12 ranked the best for the general health, and the Oxford-12 for the disease/site-specific questionnaires. These two questionnaires could therefore be recommended as the most appropriate for use with a large knee arthroplasty database in a cross-sectional population.
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| 10. |
- Dunbar, Michael J, et al.
(författare)
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Translation and validation of the Oxford-12 item knee score for use in Sweden
- 2000
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Ingår i: Acta Orthopaedica Scandinavica. - : Medical Journals Sweden AB. - 0001-6470. ; 71:3, s. 268-274
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Tidskriftsartikel (refereegranskat)abstract
- The Oxford-12 Item Knee Score is a recently developed and validated patient-completed outcome measure designed specifically for use with knee arthroplasty in the United Kingdom. We have translated this questionnaire into Swedish and tested the validity and reliability of the translated version in a cross-sectional study by a postal survey to 1,200 randomly selected patients from the Swedish Knee Arthroplasty Register. Swedish versions of the WOMAC, Nottingham Health Profile, SF-36, SF-12, and the Sickness Impact Profile were employed in the validation process. We also tested feasibility and patient-burden parameters. The translated version appeared to be linguistically and culturally equivalent to the original version with good validity and reliability. Indirect measures of responsiveness indicated that it is at least as responsive to relevant knee arthroplasty patient states as the previously validated Swedish version of the WOMAC. Application of the translated questionnaire to this population is feasible with minimal imposed patient-burden. The Swedish translation of the Oxford-12 Item Knee Score is a valid and reliable tool for outcome studies on knee arthroplasty patients.
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| 11. |
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| 12. |
- Flivik, Gunnar, et al.
(författare)
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Effects of lamination on the strength of bone cement
- 1997
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Ingår i: Acta Orthopaedica Scandinavica. - : Medical Journals Sweden AB. - 0001-6470. ; 68:1, s. 55-58
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Tidskriftsartikel (refereegranskat)abstract
- To improve cement penetration into the cancellous bone of the acetabulum in hip arthroplasty, sequential cementation of each anchoring hole may be feasible. Since this procedure creates laminations in the cement, we have determined the conditions under which such laminations affect the strength of the cement. Cement bars made at 2, 3 or 4 minutes after the start of cement mixing and with either dry laminations or laminations including blood or saline were tested for tensile strength. Solid unlaminated bars were used as references. Dry and saline laminations made up to 4 minutes after the start of cement mixing did not reduce the strength of the cement. However, there was a time-dependent decrease in cement strength if blood was entrapped in the interface. In such cases, there was a decrease in strength for laminations made at 4 minutes, at 3 minutes this was less pronounced and at 2 minutes no weakening at all was noted. Our findings indicate that a sequential cementation procedure is permissible as regards cement strength, provided it is performed with 2-3 minutes after the start of cement mixing. If the cement area is kept free from blood, the time may be prolonged up to 4 minutes, without the risk of weakening the cement strength.
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| 13. |
- Flivik, Gunnar, et al.
(författare)
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Improved acetabular pressurization gives better cement penetration : In vivo measurements during total hip arthroplasty
- 2004
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Ingår i: The Journal of Arthroplasty. - : Elsevier BV. - 0883-5403 .- 1532-8406. ; 19:7, s. 911-918
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Tidskriftsartikel (refereegranskat)abstract
- During total hip arthroplasty, the intraoperative cementation pressure was measured inside one of the acetabular anchorage holes. Patients were randomized to pressurization of cement with either a conventional pressurizer or a sequential method including individual pressurization of each anchorage hole. The pressure was correlated to the cement penetration measured on digital radiographs. The early peak pressures were higher for the sequential method, resulting in a significantly better penetration of 2.8 mm compared with 0.7 mm with the conventional pressurizer. We found a strong correlation between early peak cementation pressures and cement penetration into the cancellous bone of the anchoring holes, indicating a cause-effect relationship at this early stage. The highest peak pressures were achieved during the later cup insertion, but these pressures did not correlate with the cement penetration. We conclude that conventional methods for cement pressurization in the acetabulum may not be optimal. © 2004 Elsevier Inc. All rights reserved.
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| 14. |
- Flivik, Gunnar, et al.
(författare)
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Is removal of subchondral bone plate advantageous in cemented cup fixation? A randomized RSA study.
- 2006
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Ingår i: Clinical Orthopaedics and Related Research. - : Ovid Technologies (Wolters Kluwer Health). - 0009-921X. ; 448, s. 164-172
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Tidskriftsartikel (refereegranskat)abstract
- There is uncertainty regarding whether and how the subchondral bone plate should be treated during acetabular preparation for cemented cup fixation in a total hip arthroplasty. We hypothesized that removing the bone plate would improve the cement-bone interface without jeopardizing the initial cup stability, and therefore, be advantageous to long-term cup survival. We randomized 50 patients with primary osteoarthritis into two groups, one for removal and one for retention of the subchondral bone plate. The patients were evaluated during 2 years followup using repeated radiostereometric examinations, analyses of radiolucent lines, and clinical followups. Patient scoring was done using the Western Ontario and McMaster Universities Osteoarthritis Index, the Short Form-12, and the Harris hip score. Removal of the subchondral bone plate resulted in a superior cement-bone interface with less development of radiolucent lines. The radiostereometry results showed small migrations in both groups. We found no differences in cup stability between groups, although a difference was observed in rotational behavior with the removal group stabilizing in a slightly vertical position whereas the retention group showed slight but progressive rotation into a more horizontal position. No differences were found during clinical followups. Removing the subchondral bone plate, where possible, improves the cement-bone interface without jeopardizing the stability, implying better long-term cup survival. However, it is a more demanding surgical technique.
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| 15. |
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| 16. |
- Hansson, Ulrik, et al.
(författare)
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A randomised RSA study of Peri-Apatitetrade mark HA coating of a total knee prosthesis.
- 2008
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Ingår i: Knee. - : Elsevier BV. - 1873-5800. ; 15, s. 211-216
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In total knee replacement, sound early fixation of the prosthesis is crucial for achieving a good long-term result and for minimising the risk of loosening. Various types of prosthetic material, different surface textures and shapes and the incorporation of screws or pegs have been used to achieve good fixation, particularly in the uncemented knee. Hydroxyapatite (HA) coating of prosthetic joint components is another technique used to enhance early stability and so to improve the longevity of the prosthesis-bone fixation. HA ceramic coatings are mostly plasma sprayed onto the fixation surface of the implant. Plasma spraying is largely a 'line of sight' technique and as such there are difficulties involved when covering three-dimensional planes, such as porous beaded fixation surfaces typically found on several knee prostheses. The objective of this study was to assess the clinical performance of the solution-deposited HA coating, Peri-Apatitetrade mark , with regard to its ability to stimulate an endurable and stable implant fixation. PATIENTS AND METHODS: We randomised 60 patients into two groups; one group received the porous coated prosthesis with solution-deposited HA, and the other group received a prosthesis without HA. Radiostereometric examination was used as the primary tool for measuring migration in the prosthetic components. RESULTS: There was a lower incidence of early subsidence in the Peri-Apatitetrade mark group. At 24 months there were no differences in clinical scorings or maximal total point motion. CONCLUSION: Addition of solution-deposited HA coating appears to provide better early stable fixation in a porous coated knee prosthesis.
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| 17. |
- Hansson, Ulrik, et al.
(författare)
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Histologic reactions to particulate wear debris in different mesenchymal tissues : Studies on the nonreplaced compartment from revised uni-knees
- 2004
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Ingår i: The Journal of Arthroplasty. - : Elsevier BV. - 0883-5403 .- 1532-8406. ; 19:4, s. 481-487
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Tidskriftsartikel (refereegranskat)abstract
- The interface between bone and artificial-joint implants consists of soft tissue. This tissue varies from fibrocartilage to loose fibrous tissue. Tissues that resemble those can be found in normal joints. Sixteen knees with unicompartmental knee prostheses, revised because of excessive wear of the tibial insert, were studied. Synovium, synovial fluid, cartilage, and bone from the nonreplaced compartment were studied with light microscopy. We found wear particles and reactions to those in all tissues except cartilage. In the subchondral bone, we found osteolytic-like processes undermining the cartilage peripherally. Our conclusion from these findings is that the histologic composition of the bone-implant interface might be an important factor regarding the reaction of the tissue to wear particles and, thus, component fixation. © 2004 Elsevier Inc. All rights reserved.
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| 18. |
- Hansson, Ulrik, et al.
(författare)
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Mobile vs. fixed meniscal bearing in total knee replacement A randomised radiostereometric study.
- 2005
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Ingår i: Knee. - : Elsevier BV. - 1873-5800. ; 12:6, s. 414-418
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Tidskriftsartikel (refereegranskat)abstract
- 52 knees scheduled for a total knee arthroplasty were randomised to either a fixed or a mobile polyethylene bearing. The design was identical in all parts. The knee systems used were the Rotaglide Total Knee System (RTK) (R) and the Nuffield Total Knee System (NTK) (R), both from the same manufacturer (Corin Medical Ltd., UK). All knees implanted were uncemented. The patients were followed for 2 years clinically and with radiostereometric analyses to assess migration over time and inducible displacement of the tibial component. Separate analysis of the mobility of the tibial insert in the knees with a mobile bearing was also made. The migration measured with RSA between the I st and 2nd year expressed as maximum total point motion (MTPM) might predict the risk of loosening of the implant.
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| 19. |
- Hansson, Ulrik, et al.
(författare)
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Once-weekly oral medication with alendronate does not prevent migration of knee prostheses : A double-blind randomized RSA study
- 2009
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Ingår i: Acta Orthopaedica. - : Informa Healthcare. - 1745-3674 .- 1745-3682. ; 80:1, s. 41-45
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Tidskriftsartikel (refereegranskat)abstract
- Background and purposeEarly migration of joint replacements is an effect of poor fixation and can predict late loosening. By reducing the bone resorption after implantation of a joint replacement, it should be possible to enhance the initial fixation of the implant. We studied the effect of once-weekly treatment with alendronate after knee replacement.Patients and methodsWe recruited 60 patients (60 knees) with gonarthrosis who were scheduled for a total knee replacement. They were operated on with identical implants and uncemented fixation. 30 patients were treated with a bisphosphonate (alendronate) and 30 patients underwent placebo treatment. The treatment started postoperatively and continued on a weekly basis for 6 months. The fixation of the implants was measured with repeated radiostereometry for 2 years.ResultsThere was no difference in migration of implants between the two groups.ConclusionWith uncemented fixation of knee implants, no benefit of once-weekly treatment with alendronate, starting postoperatively, could be seen during a 2-year follow-up period.
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| 20. |
- Hansson, Ulrik, et al.
(författare)
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Once-weekly oral medication with alendronate does not prevent migration of knee prostheses
- 2009
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Ingår i: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3682 .- 1745-3674. ; 80:1, s. 41-45
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose Early migration of joint replacements is an effect of poor fixation and can predict late loosening. By reducing the bone resorption after implantation of a joint replacement, it should be possible to enhance the initial fixation of the implant. We studied the effect of once-weekly treatment with alendronate after knee replacement. Patients and methods We recruited 60 patients (60 knees) with gonarthrosis who were scheduled for a total knee replacement. They were operated on with identical implants and uncemented fixation. 30 patients were treated with a bisphosphonate (alendronate) and 30 patients underwent placebo treatment. The treatment started postoperatively and continued on a weekly basis for 6 months. The fixation of the implants was measured with repeated radiostereometry for 2 years. Results There was no difference in migration of implants between the two groups. Conclusion With uncemented fixation of knee implants, no benefit of once-weekly treatment with alendronate, starting postoperatively, could be seen during a 2-year follow-up period.
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| 21. |
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| 22. |
- Juliusson, Rigmor, et al.
(författare)
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Circulating blood diminishes cement penetration into cancellous bone. In vivo studies of 21 arthrotic femoral heads
- 1995
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Ingår i: Acta Orthopaedica Scandinavica. - 0001-6470. ; 66:3, s. 234-238
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Tidskriftsartikel (refereegranskat)abstract
- We compared the penetration depth into cancellous bone when pressurizing cement at predetermined pressure levels, and at different times after cement mixing, in 21 arthrotic femoral heads during total hip replacement. To determine the influence of circulating blood on cement penetration, cement was injected into holes drilled into the femoral head before and after osteotomy of the femoral neck. The penetration of cement increased on the average 100 percent in the absence of circulation.
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| 23. |
- Kiernan, Sverrir, et al.
(författare)
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The importance of adequate stem anteversion for rotational stability in cemented total hip replacement: A radiostereometric study with ten-year follow-up.
- 2013
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Ingår i: The Bone & Joint Journal. - 2049-4408. ; 95B:1, s. 23-30
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Tidskriftsartikel (refereegranskat)abstract
- Progressive retroversion of a cemented stem is predictive of early loosening and failure. We assessed the relationship between direct post-operative stem anteversion, measured with CT, and the resulting rotational stability, measured with repeated radiostereometric analysis over ten years. The study comprised 60 cemented total hip replacements using one of two types of matt collared stem with a rounded cross-section. The patients were divided into three groups depending on their measured post-operative anteversion (< 10°, 10° to 25°, > 25°). There was a strong correlation between direct post-operative anteversion and later posterior rotation. At one year the < 10° group showed significantly more progressive retroversion together with distal migration, and this persisted to the ten-year follow-up. In the < 10° group four of ten stems (40%) had been revised at ten years, and an additional two stems (20%) were radiologically loose. In the 'normal' (10° to 25°) anteversion group there was one revised (3%) and one loose stem (3%) of a total of 30 stems, and in the > 25° group one stem (5%) was revised and another loose (5%) out of 20 stems. This poor outcome is partly dependent on the design of this prosthesis, but the results strongly suggest that the initial rotational position of cemented stems during surgery affects the subsequent progressive retroversion, subsidence and eventual loosening. The degree of retroversion may be sensitive to prosthetic design and stem size, but < 10° of anteversion appears deleterious to the long-term outcome for cemented hip prosthetic stems.Cite this article: Bone Joint J 2013;95-B:23-30.
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| 24. |
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| 25. |
- Lauge-Pedersen, Henrik, et al.
(författare)
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Arch-shaped versus flat arthrodesis of the ankle joint: strength measurements using synthetic cancellous bone
- 2002
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Ingår i: Proceedings of the Institution of Mechanical Engineers. Part H: Journal of Engineering in Medicine. - : SAGE Publications. - 0954-4119 .- 2041-3033. ; 216:H1, s. 43-49
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Tidskriftsartikel (refereegranskat)abstract
- The aim Of this Study was to see if preservation of the arch shape of the ankle at arthrodesis contributes to stability. The ankle joint was simulated by paired blocks of a synthetic material corresponding to rheumatoid cancellous bone with low stiffness and strength. Flat end constructs with and without subchondral bone were compared with arch-shape constructs with and without subchondral bone. The pairs were fixed with two screws simulating an arthrodesis. These constructs were then tested to failure in four-point bending and torque. In four-point bending the subchondral bone increased the strength, regardless of shape. Stiffness was higher in the arch-shaped specimens but was not influenced b the subchondral bone. In torque, both arch-shape and subchondral bone increase the strength. Stiffness was increased by arch-shape but not subchondral bone. The results imply that the arch-shape and subchondral bone should be preserved when performing an ankle arthrodesis, especially in weak rheumatoid bone.
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| 26. |
- Lohmander, L. Stefan, et al.
(författare)
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Intra-articular hyaluronan injections in the treatment of osteoarthritis of the knee : A randomised, double blind, placebo controlled multicentre trial
- 1996
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967. ; 55:7, s. 424-431
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Tidskriftsartikel (refereegranskat)abstract
- Objective - To assess the effects of intraarticular injections of hyaluronan on symptoms of knee osteoarthritis (OA). Methods - Two hundred and forty patients with symptomatic, radiological knee OA were randomly assigned to treatment with weekly injections for five weeks with either 25 mg of high molecular weight hyaluronan or vehicle. Results were evaluated at weeks 1, 2, 3, 4, 5, 13, and 20 by visual analogue scales (pain, function, motion, activity), algofunctional index, and global evaluation by patient and investigator. Analysis was by 'intention to treat', 'per protocol), and area under the curve principles on unstratified patient groups and for patients stratified into four groups of equal size by age and baseline algofunctional index. Results - No serious side effects were reported. At 20 weeks both treatment groups were improved compared with baseline, with no difference between unstratified groups treated with placebo or hyaluronan. Comparison of treatment-groups stratified by age and baseline algofunctional index revealed a significant-difference in favour of hyaluronan over placebo (pain, activity, algofunctional index, global evaluations by patient-and investigator) for patients older than 60 years and with a baseline algofunctional index greater than 10. There was no clinically relevant difference between the two treatments for the other three stratified subgroups of younger age or fewer symptoms. Similar results were obtained by area under the curve, intention to treat, and per protocol analysis. Conclusions-Patients older than 60 years with knee osteoarthritis and with significant symptoms corresponding to an index of severity of knee disease of 10 or more, comprise the group most likely to benefit from treatment with intra-articular hyaluronan injections.
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| 27. |
- Löfgren, Håkan, et al.
(författare)
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Rigid Fusion After Cloward Operation for Cervical Disc Disease Using Autograft, Allograft, or Xenograft : A Randomized Study With Radiostereometric and Clinical Follow-Up Assessment
- 2000
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Ingår i: Spine. - 0362-2436 .- 1528-1159. ; 25:15, s. 1908-1916
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Tidskriftsartikel (refereegranskat)abstract
- Study Design. In this study, 43 patients scheduled for a single-level cervical Cloward procedure for disc disease were randomized prospectively to fusion with autograft, allograft, or xenograft.Objective. To outline any differences in fusion over time in terms of final mobility and clinical outcome between the three bone grafts.Summary of Background Data. Fusion is used to relieve pain from a spinal segment. The bovine xenograft gives a fibrous fusion in contrast to the solid bone fusion obtained with autograft from the iliac crest, but no definite differences in clinical outcome have been shown previously after surgery at a single level.Methods. By use of radiostereometric analysis, 33 patients were observed after 6, 12, and 24 to 50 (mean, 37) months. All 43 patients underwent clinical examination, which involved pain rating before and after surgery, with a final follow-up assessment by an unbiased observer.Results. Mobility could be demonstrated in 9 patients after 1 year and in 6 patients at the final follow-up assessment, without pain, and with no difference between bone grafts. The patients who received autograft experienced a greater reduction of pain than the patients treated with xenograft.Conclusions. Most of the patients healed with a rigid fusion no matter which graft was used, but the healing process took longer than expected. The clinical results were not influenced by whether mobility could be demonstrated. There was a tendency toward better clinical results in the patients treated with autograft.
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| 28. |
- Manda, Krishnagoud, 1983-, et al.
(författare)
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Finite element simulations of a focal knee resurfacing implant applied to localized cartilage defects in a sheep model
- 2011
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Ingår i: Journal of Biomechanics. - : Elsevier BV. - 0021-9290 .- 1873-2380. ; 44:5, s. 794-801
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Tidskriftsartikel (refereegranskat)abstract
- Articular resurfacing metal implants have recently been tested in animal models to treat full thickness localized articular cartilage defects, showing promising results. However, the mechanical behavior of cartilage surrounding the metal implant has not been studied yet as it is technically challenging to measure in vivo contact areas, pressures, stresses and deformations from the metal implant. Therefore, we implemented a detailed numerical finite element model by approximating one of the condyles of the sheep tibiofemoral joint and created a defect of specific size to accommodate the implant. Using this model, the mechanical behavior of the surrounding of metal implant was studied. The model showed that the metal implant plays a significant role in the force transmission. Two types of profiles were investigated for metal implant. An implant with a double-curved profile, i.e., a profile fully congruent with the articular surfaces in the knee, gives lower contact pressures and stresses at the rim of the defect than the implant with unicurved spherical profile. The implant should be placed at a certain distance into the cartilage to avoid damage to opposing biological surface. Too deep positions, however, lead to high shear stresses in the cartilage edges around the implant. Mechanical sealing was achieved with a wedge shape of the implant, also useful for biochemical sealing of cartilage edges at the defect.
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| 29. |
- Miyamoto, H, et al.
(författare)
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Three-dimensional analysis of the movement of lumbar spinal nerve roots in nonsimulated and simulated adhesive conditions
- 2003
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Ingår i: Spine. - 0362-2436. ; 28:20, s. 2373-2380
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Tidskriftsartikel (refereegranskat)abstract
- Study Design. Biomechanical analysis of the movement of the lumbar spinal nerve roots (NRs). Objectives. The characteristics of the movement of lumbar spinal NRs corresponding to the change of posture were three-dimensionally analyzed in nonsimulated and simulated adhesion conditions using a porcine model. Summary of Background Data. There is a paucity of data on the movement of NRs. Materials and Methods. Thirty two NRs of four pig cadavers were investigated. ( study 1) Two tantalum beads were sutured on respective NRs from L3 to L6. Five beads were put into each bony structure as reference points. The porcine body was put on the cage designed for three-dimensional radiostereometric analysis. Two oblique radiographs were simultaneously taken at flexion, neutral, and extension. ( study 2) After study 1, either L4 NR was ligated onto the adjacent bone to mimic monoradicular adhesion. Radiographs were taken in the same manner. The movements of the beads on NRs relative to immobile standard points in each vertebra were analyzed. Results. The movement of NRs was characterized as a combination of stretching/slackening and pendulum motion. The distance that NRs were stretched/slackened, the excursion, and the angles that NRs moved were: 0.39 +/- 0.29 mm, 1.81 +/- 0.63 mm, and 10.46 +/- 5.93degrees ( in nonadhesion), and 0.30 +/- 0.20 mm, 1.02 +/- 0.50 mm, and 7.13 +/- 3.79degrees ( in simulated adhesion), respectively. Conclusion. Adhesion might play a part in the pathogenesis of lumbar spinal disorders because mechanical irritation secondary to stretching/slackening and pendulum motion might be concentrated at the distal part of NRs, adjacent to adhesion site, which has less cerebrospinal fluid and is close to dorsal root ganglion.
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| 30. |
- Molt, Mats, et al.
(författare)
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A randomized RSA study concentrating especially on continuous migration : A randomized RSA study concentrating especially on continuous migration
- 2016
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Ingår i: Acta Orthopaedica. - : Informa UK Limited. - 1745-3674 .- 1745-3682. ; 87:3, s. 262-267
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose — There is a general call for phased introduction of new implants, and one step in the introduction is an early evaluation of micromotion. We compared the micromotion in the Triathlon and its predecessor, the Duracon total knee prosthesis, concentrating especially on continuous migration over 5 years of follow-up. Patients and methods — 60 patients were randomized to receive either a cemented Triathlon total knee prosthesis or a cemented Duracon total knee prosthesis. 3-D tibial component migration was measured by radiostereometric analysis (RSA) at 3 months and at 1, 2, and 5 years. Results — There was no statistically significant difference in maximum total point motion (MTPM) between the 2 groups (p = 0.1). The mean MTPM at 5 years for the Duracon was 1.10 (SD 1.21) mm and for the Triathlon it was 0.66 (SD 0.38) mm. The numbers of continuously migrating prostheses were similar in the groups at the fifth year of follow-up; 6 of 21 prostheses in the Duracon group and 3 of 21 in the Triathlon group had migrated more than 0.3 mm between the second year and the fifth year of follow-up (p = 0.2). Interpretation — The Triathlon has a micromotion pattern similar to that of the Duracon total knee system at both short-term and medium-term follow-up, and may therefore, over time, show the same good long-term mechanical stability.
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| 31. |
- Nilsson, Kjell G., 1953-
(författare)
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Kinematics and fixation of total knee arthroplasties : a clinical, radiographic, scintimetric, and roentgen stereophotogrammetric evaluation
- 1992
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aseptic loosening of the tibial component is an important cause of failure after total knee arthroplasty. Bone destruction often claimed to be caused by the cement makes the revision difficult. In order to treat younger patients, uncemented fixation has been introduced, but the etiology to loosening is multifactorial and only partly known. Early detection of implant migration facilitates research in this field but is difficult using conventional techniques. In this study modified versions of roentgen stereophotogrammetric analysis (RSA) were developed to obtain accurate and standardized evaluations facilitating comparison between prosthetic designs. The method was used to record the efficacy of cemented and uncemented fixation of different designs of the tibial component, to determine the accuracy of scintimetry in the detection of early aseptic loosening, and to analyse the in vivo kinematics of knee arthroplasties with different design and stability between the joint surfaces.Forty-three arthroplasties with comparatively high inherent stability of the joint surfaces were randomized to cemented or uncemented fixation of the tibial component. In all groups micromovements were rather large, but with no differences between the cemented and uncemented components. The preoperative diagnosis (arthrosis OA, n=25; rheumatoid arthritis RA, n=18) did not influence the magnitude of micromotion.20 arthroplasties with the same design as above but equipped with an intramedullary stem, were randomized to cemented or uncemented fixation in patients with RA. Cement improved the fixation. Uncemented stemmed components displayed micromovements seemingly larger than unstemmed ones.34 arthroplasties with an unconstrained design of the joint area and fixed to the tibia with four pegs were randomized to cemented or uncemented fixation in patients with OA. When used uncemented 4 screws were added. Compared with previously investigated designs small micromotions were recorded, and especially in the cemented cases. Uncemented components with thin polyethylene inserts displayed larger initial micromotions. The preoperative deformity influenced the direction of the micromotion.33 knees were followed prospectively with RSA and scintimetry to evaluate any correlation between these methods. Low activity under the tibial component at 2 years implied prosthetic stability, whereas high activity indicated instability or high bone remodelling caused by the preoperative malalignment.The in vivo kinematics in three different designs of knee arthroplasties were analyzed during active flexion and extension without weight-bearing. Each type of prosthesis displayed design-specific abnormalities when compared with a normal material. Pronounced posterior tibial translations were recorded during flexion regardless whether the posterior cruciate ligament had been sacrificed or not. Data from the kinematic and the fixation studies suggest that movements restricted by the design of the joint area are transmitted to the bony interface with design-specific micromotions as the result.Analysis of knee joint kinematics during extension and weight-bearing revealed small alterations compared with non-weight-bearing. Evaluation of the three-dimensional movements in terms of helical axis rotations and translations confirmed the constrained or unconstrained in vivo behaviour of the designs under study. This analysis also facilitated the interpretation of the kinematic behaviour of the prosthetic knees and may be of value in the evaluation of new designs.
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| 32. |
- Olsson, O, et al.
(författare)
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A biomechanical study on fixation stability with twin hook or lag screw in artificial cancellous bone
- 2002
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Ingår i: International Orthopaedics. - : Springer Science and Business Media LLC. - 1432-5195 .- 0341-2695. ; 26:6, s. 349-355
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Tidskriftsartikel (refereegranskat)abstract
- The twin hook has been developed as an alternative to the conventional lag screw to be combined with a barrelled side-plate in the treatment of trochanteric hip fractures. With two oppositely directed apical hooks introduced into the subchondral bone of the femoral head, the twin hook provides different stabilising properties to the lag screw. The femoral head purchase of the twin hook and the lag screw were compared in a biomechanical study using artificial cancellous bone, and responses to axial and torsional loading was determined. A distinct yield point in load and torque was noted for the lag screw, representing failure of the laminas supporting the threads. For the twin hook, gradual increase of load and torque occurred during impaction of the bone supporting the hooks. The peak loads and torques were higher for the lag screw, but were similar for both devices after 8 rum deformation. The stiffness was higher for the lag screw, but in counter-clockwise rotation the stiffness for the lag screw was negligible. The twin hook appeared to provide fixation stability comparable to that offered by the lag screw, but with conceivable advantages in terms of a deformation response involving bone impaction and gradually increasing stability.
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| 33. |
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| 34. |
- Roos, Ewa M., et al.
(författare)
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Substantial disability 3 months after arthroscopic partial meniscectomy: : A prospective study of patient-relevant outcomes
- 2000
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Ingår i: Arthroscopy. - : Elsevier BV. - 0749-8063. ; 16:6, s. 619-626
-
Tidskriftsartikel (refereegranskat)abstract
- To our knowledge, this is the first prospective study using validated questionnaires to assess patient-relevant outcomes after arthroscopic partial meniscectomy. Data from the Knee Injury and Osteoarthritis Outcome Score (KOOS), the SF-36 Medical Outcomes Study Short-Form Health Survey, and the Lysholm Knee Scoring Scale were available for 74 consecutive patients (50 males, 24 females; mean age, 45 years) with isolated meniscus tear (n = 47) or meniscus tear combined with cartilage damage (n = 27). At postoperative follow-up (mean, 14.4 weeks) significant improvement was seen, but despite only minor pain and other symptoms postoperatively, significant physical disability and handicap were reported. Postoperatively, 30% of patients were active in sports compared with 63% before injury. A sedentary lifestyle was reported by 38% compared with 9% before injury. We conclude that patient-relevant outcomes provide additional information and should be assessed after arthroscopic partial meniscectomy. We further suggest that preoperative information for the meniscectomy patient should include a realistic expected functional outcome.
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| 35. |
- Ryd, Leif, et al.
(författare)
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Methods for determining the accuracy ofradiostereometric analysis (RSA)
- 2000
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Ingår i: Acta Orthopaedica Scandinavica. - : Medical Journals Sweden AB. - 0001-6470. ; 71:4, s. 403-408
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Tidskriftsartikel (refereegranskat)abstract
- The problem of determining the noise level in any measuring system remains urgent. Radiostereometric analysis (RSA) is a radiographic system of unique accuracy which has applications in areas where minute motions or no motion at all occurs. Examples are micromotion between endoprostheses and bone and in fracture healing.We have determined the accuracy of the RSA system as applied to a clinical series of spinal fusions, where the conditions for RSA were not optimal. Using the usual test-retest methodology on a phantom, we showed that its accuracy can be grossly overestimated in the individual case.We found considerable variations in the accuracy in the individual case, depending on the rigid-body configuration. The overall accuracy, expressed as 3-D "vectors" for rotation and translation, respectively, correlated with the condition number, a method for characterizing the marker configuration. Indeed, the condition number explained as much as 92% of the variation in overall rotation. This condition number, however, cannot be used to analyze the accuracy of one degree of freedom of rotation alone. Mathematical simulation of the accuracy in the individual case of the individual dimension, using in-house software, showed that the accuracy (95% confidence) varied between 0.4 and 4.6 degrees of rotation about the transverse axis, corresponding to a clinical stress series of extension and flexion.
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| 36. |
- Ryd, Leif
(författare)
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Utmärkta resultat efter artroskopi
- 2002
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Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 99, s. 4651-4655
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 37. |
- Soderberg, B., et al.
(författare)
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Roentgen Stereophotogrammetric Analysis of Motion between the Bone and the Socket in a Transtibial Amputation Prosthesis : A Case Study
- 2003
-
Ingår i: Journal of prosthetics and orthotics. - : Ovid Technologies (Wolters Kluwer Health). - 1040-8800 .- 1534-6331. ; 15:3, s. 95-99
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Tidskriftsartikel (refereegranskat)abstract
- High-tech development within prosthetics for lower limb amputees can benefit from high-tech methods to study the socket fit. Roentgen stereophotogrammetry is one such method with high resolution to study stability with point motion and segment motion simultaneously to show how well bonded the socket is to the stump. It has been used to follow results of total joint replacement concerning loosening and wear of components. In this study, one transtibial amputee was examined with tantalum bone markers implanted through skin and also glued into the hard socket. Four different prosthetic suspensions were used, and we simulated four different gait cycle positions and recorded the micromotions between the tibial bone segment and the hard socket three-dimensionally. The vertical motion varied 10 to 30 mm and the AP motion 0 to 15 mm. For the first time, we could measure rotation of the socket on the stump about a vertical axis. The rotation in the transversal plane was 7.5 outward. Airtight sleeve with expulsion valve gave the best stability.
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| 38. |
- Stålman, Anders, et al.
(författare)
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No implant migration and good subjective outcome of a novel customized femoral resurfacing metal implant for focal chondral lesions
- 2018
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Ingår i: Knee Surgery, Sports Traumatology, Arthroscopy. - : Springer. - 0942-2056 .- 1433-7347. ; 26:7, s. 2196-2204
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Managing focal cartilage injuries in the middle-aged patient poses a challenge. Focal prosthetic inlay resurfacing has been proposed to be a bridge between biologics and conventional joint arthroplasty. Patient selection and accurate implant positioning is crucial to avoid increased contact pressure to the opposite cartilage surface. A customized femoral condyle implant for focal cartilage injuries was designed to precisely fit each patient’s individual size and location of damage. The primary objective was to assess implant safety profile, surgical usability of the implant and instruments, and implant migration with radiostereometric analysis (RSA). Methods: Ten patients 36–56 years with focal chondral defects, ICRS 3–4 of the femoral cartilage and failed earlier conservative or surgical interventions with VAS pain > 40. The patients were followed for 2 years with subjective outcome measures (VAS, EQ5D, KOOS) and RSA. The customized implant and guide instruments were manufactured by computer-aided design/computer-aided manufacturing (CAD/CAM) techniques using MRI data. Results: VAS, EQ5D and KOOS showed improvements that reached significance for VAS (p ≤ 0.001), Tegner (p = 0.034) and the KOOS subscores ADL (p = 0.0048), sport and recreation (p = 0.034) and quality of life (p = 0.037). VAS and KOOS scores improved gradually at 3, 6 and 12 months. The improvements in EQ5D, KOOS pain and KOOS symptoms did not reach statistical significance. No infections, deep venous thrombosis or other complications occured in the postoperative period. No radiographic signs of damage to the opposing tibial cartilage was noted. The surgical usability of implants and instruments were good. RSA did not show any implant migration. Conclusion: This is the first clinical report of a new customized, focal knee resurfacing system. The short-term implant safety and patient-related outcome measures showed good-to-excellent results. Level of evidence: Prospective case series, Level 4.
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| 39. |
- Thompson, Mark, et al.
(författare)
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Compressive and Shear Properties of Commercially Available Polyurethane Foams
- 2003
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Ingår i: Journal of Biomechanical Engineering. - : ASME International. - 0148-0731 .- 1528-8951. ; 125:5, s. 732-734
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Tidskriftsartikel (refereegranskat)abstract
- Background: The shear properties of rigid polyurethane (PU-R) foams, routinely used to simulate cancellous bone, are not well characterized. Method of approach: The present assessment of the shear and compressive properties of four grades of Sawbones "Rigid cellular" PU-R foam tested 20 mm gauge diameter dumb-bell specimens in torsion and under axial loading. Results: Shear moduli ranged from 13.3 to 99.7 MPa, shear strengths from 0.7 MPa to 4.2 MPa. Compressive yield strains varied little with density while shear yield strains had peak values with "200 kgm-3" grade. Conclusions: PU-R foams may be used to simulate the elastic but not failure properties of cancellous bone.
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| 40. |
- Thompson, M.S., et al.
(författare)
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A comparison of structural and mechanical properties in cancellous bone from the femoral head and acetabulum
- 2004
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Ingår i: Proceedings of the Institution of mechanical engineers. Part H, journal of engineering in medicine. - : SAGE Publications. - 0954-4119 .- 2041-3033. ; 218:6, s. 425-429
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical interlock obtained by penetration of bone cement into cancellous bone is critical to the success of cemented total hip replacement (THR). Although acetabular component loosening is an important mode of THR failure, the properties of acetabular cancellous bone relevant to cement penetration are not well characterized. Bone biopsies (9 mm diameter, 10 mm long) were taken from the articular surfaces of the acetabulum and femoral head during total hip replacement. After mechanical and chemical defatting the two groups of bone specimens were characterized using flow measurement, mechanical testing and finally serial sectioning and three-dimensional computer reconstruction. The mean permeabilities of the acetabular group (1.064 × 10-10 m2) and femoral group (1.155 × 10-10 m2) were calculated from the flow measurements, which used saline solution and a static pressure of 9.8 kPa. The mean Young's modulus, measured non-destructively, was 47.4 MPa for the femoral group and 116.4 MPa for the acetabular group. Three-dimensional computer reconstruction of the specimens showed no significant differences in connectivity and porosity between the groups. Results obtained using femoral head cancellous bone to investigate bone cement penetration and fixation are directly relevant to fixation in the acetabulum. © IMechE 2004.
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| 41. |
- Toksvig-Larsen, Søren, et al.
(författare)
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The Porous-Coated Anatomic Total Knee Experience. Special Emphasis on Complications and Wear
- 1996
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Ingår i: Journal of Arthroplasty. - 0883-5403. ; 1:11, s. 11-17
-
Tidskriftsartikel (refereegranskat)abstract
- One hundred sixty knees in 141 patients with the Primary Porous-Coated Anatomic prosthesis (Howmedica, Rutherford, NJ) were evaluated after a follow-up period of 5.6 years (range, 1–10 years). One hundred six knees were in the latest follow-up evaluation, including clinical examination and a defined standing radiograph with a follow-up period of 6.3 years (range, 3–10 years). Survivorship analysis regarding the cumulative revision rate (including completion with a patellar component) was 0.88 at the 8-year and 0.84 at the 10-year follow-up examination. The clinical result was satisfying/good, with a mean Hospital for Special Surgery score of 83 (range, 39–97). Five percent had thinning greater than 30% of the tibial component. The wear was calculated to be 1.0 mm (range, 0–9 mm), including three revised tibial components with heavy wear. Excluding the revised cases, the wear was 0.7 mm.
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| 42. |
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| 43. |
- Valstar, E. R., et al.
(författare)
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Guidelines for standardization of radiostereometry (RSA) of implants
- 2005
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Ingår i: Acta Orthop. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 76:4, s. 563-572
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for standardization of radiostereometric (RSA) investigations to facilitate comparison of outcome reported from different research groups. In this document, 6 research centers have agreed upon standards for terminology, description and use of RSA arrangement including radiographic set-up and techniques. Consensus regarding minimum requirements for marker stability and scatter, choice of coordinate systems, and preferred way of describing prosthetic micromotion is of special interest. Some notes on data interpretation are also presented. Validation of RSA should be standardized by preparation of protocols for assessment of accuracy and precision. Practical issues related to loading of the joint by weight bearing or other conditions, follow-up intervals, length of follow-up, radiation dose, and the exclusion of patients due to technical errors are considered. Finally, we present a checklist of standardized output that should be included in any clinical RSA paper.This document will form the basis of a detailed standardization protocol under supervision of ISO and the European Standards Working Group on Joint Replacement Implants (CEN/TC 285/WG4). This protocol will facilitate inclusion of RSA in a standard protocol for implant testing before it is released for general use. Such a protocol-also including other recognized clinical outcome parameters-will reduce the risk of implanting potentially inferior prostheses on a large scale.
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| 44. |
- Wei, Xiaochun
(författare)
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Maturation-dependent normal and injury-induced changes in rabbit knee articular cartilage
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cartilage injuries are common in sports, and may on the long term develop to osteoarthritis. Prosthetic joint replacement is not satisfactory for young active individuals with extended cartilage injuries in large weight-bearing joints. In these cases, a treatment is needed which reestablishes normal joint surfaces by biologic means. Though different cartilage repair enhancing methods have been tried, up till now none of them has achieved regrowth of hyaline cartilage which duplicates the structure and functions of normal articular cartilage. More knowledge is needed to understand the response of articular cartilage to injury. Moreover, a better understanding of how articular cartilage develops may open ways to improve the repair response. The purpose of this work was to investigate maturation-related changes of articular cartilage during postnatal maturation, and to investigate the natural healing response to full-thickness cartilage injury as a function of maturation stage.Physiologically, proteoglycan fragment concentrations in knee joint fluid decreased with maturation, and were inversely correlated with the maturation stage of the rabbits (r =- 0.69). The relatively high proteoglycan fragment concentrations in young animals might be the result of a higher turnover rate of proteoglycans in growing articular cartilage. The stiffness of articular cartilage in the rabbit knee joint decreased with maturation and was associated with an increase of subchondral bone volume fraction, and on the same time a substantial change in subchondral morphology. The results suggest that cartilage mechanics may also depend on the structural characteristics of subchondral bone.Cartilage repair in young rabbits showed a faster filling of an osteochondral defect, and an earlier differentiation to hyaline-like cartilage than repairs in adult ones. The higher repair quality in young animals compared with the adults remained up to 48 weeks. Repairs in initially adolescent and adult animals showed furthermore signs of progressing degeneration between 12 and 48 weeks with decrease of the amount of hyaline-like cartilage in the tissue. However, irrespective of age, surface disruption of the repair was common, and no repair achieved regeneration to normal articular cartilage. The compressive stiffness of the repair tissues was always markedly softer compared with normal cartilage.In preoperative joint fluid samples, TGF-ß1 decreased with maturation, and was moderately correlated with the proteoglycan fragment concentrations. Shortly after trauma, the concentrations of both substances were found increased, which was followed by a decrease up to 3 months, and then again an increase up to one year. However, meanwhile proteoglycan fragment concentrations had similar magnitude irrespective of age, TGF-ß1 concentrations never reached similarly high levels in adulthood as in infancy or adolescence. The cartilage adjacent to the defect had more signs for degeneration in younger rabbits. The similar patterns of TGF-ß1 and proteoglycan fragment concentrations during postnatal maturation may reflect the stimulatory effect of TGF-ß1 on proteoglycan synthesis. The higher TGF-ß1 concentrations in younger animals may be a reason for their better healing capacity, but also for their higher susceptibility to osteoarthritic change compared with the adult animals
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| 45. |
- Yuan, X, et al.
(författare)
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Roentgen single-plane photogrammetric analysis (RSPA.) A new approach to the study of musculoskeletal movement.
- 2002
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Ingår i: Journal of Bone and Joint Surgery: British Volume. - 2044-5377 .- 0301-620X. ; 84:6, s. 908-914
-
Tidskriftsartikel (refereegranskat)abstract
- We present a new approach for the accurate reconstruction of three-dimensional skeletal positions using roentgen single-plane photogrammetric analysis (RSPA). This technique uses a minimum of three markers embedded in each segment which allow continuous, real-time, internal skeletal movement to be measured from single-plane images, provided that the precise distance between the markers is known. A simulation study indicated that the error propagation in this approach is influenced by focus position, object position, the number of control points, the accuracy of the previous measurement of the distance between markers and the accuracy of image measurement. For reconstruction of normal movement of the knee with an input measurement error of SD = 0.02 mm, the rotational and translational differences between reconstructed and original movement were less than 0.27 degrees and 0.9 mm, respectively. Our results showed that the accuracy of RSPA is sufficient for the analysis of most movement of joints. This approach can be applied in combination with force measurements for dynamic studies of the musculoskeletal system.
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