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D W Murray - One of the best experts on this subject based on the ideXlab platform.
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Five-year results of a randomised controlled trial comparing cemented and cementless Oxford unicompartmental knee replacement using Radiostereometric Analysis
'Elsevier BV', 2021Co-Authors: D W Murray, A J Price, Kendrick Bjl, Campi S, Jackson Wfm, Dodd Caf, Er Valstar, B L KapteinAbstract:Background: Cementless fixation is an alternative to cemented unicompartmental knee replacement (UKR). The aim of this study was to determine if cementless UKR fixation is as good as cemented by comparing the five-year migration measured Radiostereometric Analysis (RSA) in a randomised controlled trial. Methods: Thirty-nine patients were randomised to receive either a cemented or a cementless Oxford UKR and were studied at intervals up to five years to assess migration with RSA and radiolucencies with radiographs. Results: During the first year there was a small and significant amount of migration, predominantly in an anterior direction, of both the cemented (0.24 mm, SD 0.32, p = 0.01) and cementless (0.26 mm, SD 0.31, p = 0.00) femoral components. Thereafter there was no significant migration in any direction. At no stage was there any significant difference between the migrations of the cemented or cementless femoral components. During the first year, particularly the first three months, the cementless tibial components subsided 0.28 mm (SD 0.19, p = 0.00). This was significantly (p = 0.00) greater than the subsidence of the cemented tibial component (0.09, SD 0.19, p = 0.28). Between the second and fifth years there was no significant migration of either cemented or cementless tibial components. At five years radiolucent lines occurred significantly less with cementless (one partial) compared to cemented (six partial and one complete) tibial components. Conclusions: As, between two and five years, there was no significant migration of cemented or cementless components, and no significant difference between them, we conclude that cementless fixation is as reliable as cemented. It may be better as there are fewer radiolucent lines.
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cemented versus cementless oxford unicompartmental knee arthroplasty using Radiostereometric Analysis a randomised controlled trial
Journal of Bone and Joint Surgery-british Volume, 2015Co-Authors: Benjamin Kendrick, Edward R Valstar, H S Gill, A J Price, B L Kaptein, W Jackson, Caf Dodd, D W MurrayAbstract:The most common reasons for revision of unicompartmental knee arthroplasty (UKA) are loosening and pain. Cementless components may reduce the revision rate. The aim of this study was to compare the fixation and clinical outcome of cementless and cemented Oxford UKAs. A total of 43 patients were randomised to receive either a cemented or a cementless Oxford UKA and were followed for two years with Radiostereometric Analysis (RSA), radiographs aligned with the bone–implant interfaces and clinical scores. The femoral components migrated significantly during the first year (mean 0.2 mm) but not during the second. There was no significant difference in the extent of migration between cemented and cementless femoral components in either the first or the second year. In the first year the cementless tibial components subsided significantly more than the cemented components (mean 0.28 mm (sd 0.17) vs. 0.09 mm (sd 0.19 mm)). In the second year, although there was a small amount of subsidence (mean 0.05 mm) there was no significant difference (p = 0.92) between cemented and cementless tibial components. There were no femoral radiolucencies. Tibial radiolucencies were narrow (< 1 mm) and were significantly (p = 0.02) less common with cementless (6 of 21) than cemented (13 of 21) components at two years. There were no complete radiolucencies with cementless components, whereas five of 21 (24%) cemented components had complete radiolucencies. The clinical scores at two years were not significantly different (p = 0.20). As second-year migration is predictive of subsequent loosening, and as radiolucency is suggestive of reduced implant–bone contact, these data suggest that fixation of the cementless components is at least as good as, if not better than, that of cemented devices. Cite this article: Bone Joint J 2015; 97-B:185–91.
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a new technique for the Radiostereometric Analysis of soft tissues
Journal of Biomechanics, 2012Co-Authors: Am M Ashmore, D W Murray, R Rout, D J Beard, A J Price, Hs S GillAbstract:Abstract Background Interest in soft tissue Radiostereometric Analysis (RSA) is rising. Previous studies have attempted to use this technique to analyse anterior cruciate ligament (ACL) graft constructs, and more recently, the movement of soft tissue as a precursor to RSA follow up of rotator cuff repairs. These methods were either prone to large amounts of marker migration, deemed unsuitable for in vivo use or, where alternative markers such as stainless steel sutures were used, lost the inherent accuracy that makes RSA an attractive tool in the first place. We describe a modification of tantalum marker balls that allows for immediate secure fixation to soft tissue in order to accurately analyse stretch and displacement of soft tissues using RSA. Methods 1.5 mm tantalum marker balls were converted to marker beads by pre-drilling with 0.3 mm holes, allowing them to be sutured directly to soft tissue. Using an established ACL graft model, the amount of marker micro-motion was then analysed by RSA after cyclical loading between 20 N and 170 N at 25 Hz for 225,000 cycles. Findings None of 40 marker beads loosened or became detached after 225,000 cycles. Mean micro-motion of the markers was Interpretation This method of attachment of tantalum markers to soft tissue is simple, reliable and provides immediate stability. Although further work is required to establish its suitability for in vivo use, this technique could potentially be used in all areas where soft tissue RSA is of interest.
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the seven year wear of highly cross linked polyethylene in total hip arthroplasty a double blind randomized controlled trial using Radiostereometric Analysis
Journal of Bone and Joint Surgery American Volume, 2011Co-Authors: Geraint Thomas, H S Gill, D W Murray, P Mclardysmith, D J Simpson, Shahid Mehmood, A Taylor, S GlynjonesAbstract:Background: The use of highly cross-linked polyethylene is now commonplace in total hip arthroplasty. Hip simulator studies and short-term in vivo measurements have suggested that the wear rate of highly cross-linked polyethylene is significantly less than that of conventional ultra-high molecular weight polyethylene. However, long-term data to support its use are limited. The aim of this study was to compare the intermediate-term steady-state wear of highly cross-linked polyethylene compared with that of conventional ultra-high molecular weight polyethylene acetabular liners in a prospective, double-blind, randomized controlled trial with use of Radiostereometric Analysis. Methods: Fifty-four patients were randomized to receive hip replacements with either conventional ultra-high molecular weight polyethylene acetabular liners (Zimmer) or highly cross-linked polyethylene liners (Longevity; Zimmer). All patients received a cemented, collarless, polished, tapered femoral component (CPT; Zimmer) and an uncemented acetabular component (Trilogy; Zimmer). Clinical outcomes were assessed and the three-dimensional penetration of the head into the socket was determined for a minimum of seven years. Linear regression was used to calculate the steady-state wear rate following the creep-dominated penetration seen during the first year. Results: At a minimum of seven years postoperatively, the mean total femoral head penetration was significantly lower in the highly cross-linked polyethylene group (0.33 mm; 95% confidence interval [CI], ±0.10 mm) than it was in the ultra-high molecular weight polyethylene group (0.55 mm; 95% CI, ±0.10 mm) (p = 0.005). The mean steady-state wear rate of highly cross-linked polyethylene was 0.005 mm/yr (95% CI, ±0.015 mm/yr), compared with 0.037 mm/yr (95% CI, ±0.019 mm/yr) for conventional ultra-high molecular weight polyethylene (p = 0.007). No patient in the highly cross-linked polyethylene group had a wear rate above the osteolysis threshold of 0.1 mm/yr, compared with 9% of patients in the ultra-high molecular weight polyethylene group. Conclusions: This study demonstrates that highly cross-linked polyethylene has a significantly lower steady-state wear rate compared with that of conventional ultra-high molecular weight polyethylene. Longer-term follow-up is required to determine if this will translate into improved clinical performance and longevity of these implants. Level of Evidence: Therapeutic Level I. See Instructions to Authors for a complete description of levels of evidence.
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the creep and wear of highly cross linked polyethylene a three year randomised controlled trial using Radiostereometric Analysis
Journal of Bone and Joint Surgery-british Volume, 2008Co-Authors: S Glynjones, H S Gill, P Mclardysmith, D W MurrayAbstract:The creep and wear behaviour of highly cross-linked polyethylene and standard polyethylene liners were examined in a prospective, double-blind randomised, controlled trial using Radiostereometric Analysis. We randomised 54 patients to receive hip replacements with either highly cross-linked polyethylene or standard liners and determined the three-dimensional penetration of the liners over three years. After three years the mean total penetration was 0.35 mm (SD 0.14) for the highly cross-linked polyethylene group and 0.45 mm (SD 0.19) for the standard group. The difference was statistically significant (p = 0.0184). From the pattern of penetration it was possible to discriminate creep from wear. Most (95%) of the creep occurred within six months of implantation and nearly all within the first year. There was no difference in the mean degree of creep between the two types of polyethylene (highly cross-linked polyethylene 0.26 mm, SD 0.17; standard 0.27 mm, SD 0.2; p = 0.83). There was, however, a significant difference (p = 0.012) in the mean wear rate (highly cross-linked polyethylene 0.03 mm/yr, SD 0.06; standard 0.07 mm/yr, SD 0.05). Creep and wear occurred in significantly different directions (p = 0.01); creep was predominantly proximal whereas wear was anterior, proximal and medial. We conclude that penetration in the first six months is creep-dominated, but after one year virtually all penetration is due to wear. Highly cross-linked polyethylene has a 60% lower rate of wear than standard polyethylene and therefore will probably perform better in the long term.
Meridith E Greene - One of the best experts on this subject based on the ideXlab platform.
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vitamin e diffused highly cross linked polyethylene in total hip arthroplasty at five years a randomised controlled trial using Radiostereometric Analysis
Journal of Bone and Joint Surgery-british Volume, 2017Co-Authors: Audrey K Nebergall, Henrik Malchau, Meridith E Greene, Mogens Berg Laursen, Poul Torben Nielsen, Anders TroelsenAbstract:Aims The objective of this five-year prospective, blinded, randomised controlled trial (RCT) was to compare femoral head penetration into a vitamin E diffused highly cross-linked polyethylene (HXLPE) liner with penetration into a medium cross-linked polyethylene control liner using Radiostereometric Analysis. Patients and Methods Patients scheduled for total hip arthroplasty (THA) were randomised to receive either the study E1 (32 patients) or the control ArComXL polyethylene (35 patients). The median age (range) of the overall cohort was 66 years (40 to 76). Results The five-year median (interquartile range) proximal femoral head penetration into the E1 was -0.05 mm (-0.13 to -0.02) and 0.07 mm (-0.03 to 0.16) for ArComXL. At three and five years, the penetration was significantly greater in the ArComXL group compared with the E1 group (p = 0.029 and p = 0.019, respectively). All patient-reported outcomes (PROs) improved significantly from the pre-operative interval compared with those at one year, and remained favourable at five years. There were no differences between the two groups at any interval. Conclusion The five-year results showed that E1 polyethylene does not wear more than the control, ArComXL. This is the longest-term RCT comparing the wear performance and clinical outcome of vitamin E diffused HXLPE with a previous generation of medium cross-linked polyethylene. Cite this article: Bone Joint J 2017;99-B:577–84.
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thirteen year evaluation of highly cross linked polyethylene articulating with either 28 mm or 36 mm femoral heads using Radiostereometric Analysis and computerized tomography
Journal of Arthroplasty, 2016Co-Authors: Audrey K Nebergall, Anders Troelsen, Henrik Malchau, Meridith E Greene, Harry E Rubash, Ola RolfsonAbstract:Abstract Background The objective of this 13-year prospective evaluation of highly cross-linked ultra high molecular weight polyethylene (HXLPE) was to (1) assess the long-term wear of HXLPE articulating with 2 femoral head sizes using Radiostereometric Analysis (RSA) and to (2) determine if osteolysis is a concern with this material through the use of plain radiographs and computerized tomography (CT). Methods All patients received a Longevity HXLPE liner with tantalum beads and either a 28-mm or 36-mm femoral head. Twelve patients (6 in each head size group) agreed to return for 13-year RSA, plain radiograph, and CT follow-up. The 1-year and 13-year plain radiographs as well as the CT scans were analyzed for the presence of osteolysis. Results The 13-year mean ± standard error steady-state wear was 0.05 ± 0.02 mm with no significant increase over time or between the 2 head size groups. Two patients' CT scans showed radiolucent regions in the acetabulum of 4.51 cm 3 and 11.25 cm 3 , respectively. In one patient, this area corresponded to a partially healed degenerative cyst treated with autograft during surgery. The second patient had an acetabular protrusio treated with autograft, and the CT scan revealed areas of remodeling of this graft. One patient's 13-year plain radiographs showed evidence of cup loosening and linear radiolucencies in zones 2 and 3. Conclusion There was no evidence of significant wear over time using RSA. The CT scans did not show evidence of osteolysis due to wear particles. These results suggest that this material has reduced wear compared to conventional polyethylene, irrespective of head size.
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five year experience of vitamin e diffused highly cross linked polyethylene wear in total hip arthroplasty assessed by Radiostereometric Analysis
Journal of Arthroplasty, 2016Co-Authors: Audrey K Nebergall, Anders Troelsen, Henrik Malchau, Harry E Rubash, Ola Rolfson, Meridith E GreeneAbstract:Abstract Background Vitamin E–diffused highly cross-linked polyethylene (VEPE) was developed to reduce oxidation without compromising mechanical strength. The purpose of this study was to evaluate VEPE in vivo using Radiostereometric Analysis (RSA) and patient-reported outcome measures (PROMs). Methods Fifty-one hips were enrolled. Each patient received a VEPE liner, a porous titanium shell, and an uncemented stem with a 32-mm cobalt–chrome femoral head. Tantalum beads were inserted into the VEPE to measure femoral head penetration using RSA. RSA radiographs and PROMs were obtained preoperatively immediately after surgery, 6 months, 1, 2, 3, and 5 years after surgery. Results Forty-seven hips returned at 3 years, and 42 hip at 5 years. The mean ± standard error of the mean proximal head penetration into the polyethylene was 0.06 ± 0.01 at 5 years. The amount of head penetration did not change significantly with increasing time in vivo. The mean ± standard error of the mean Harris Hip Score was 58 ± 2 preoperatively, which improved significantly to 93 ± 2 at 5 years (P Conclusion The head penetration into VEPE liners was low compared with non-VEPE at 5 years. After settling of the liners in the early period, no significant head penetration occurred from 2- to 5-year follow-up. All PROMs improved significantly from preoperative to postoperative and remained very favorable at 5 years. This study documents the longest-term evaluation of in vivo wear performance of VEPE.
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stable fixation of a cementless proximally coated double wedged double tapered femoral stem in total hip arthroplasty a 5 year Radiostereometric Analysis
Journal of Arthroplasty, 2016Co-Authors: Audrey K Nebergall, Anders Troelsen, Henrik Malchau, Harry E Rubash, Ola Rolfson, Meridith E GreeneAbstract:Abstract Background The objective of this 5-year prospective study of 51 hips was to assess migration of a cementless tapered femoral stem using Radiostereometric Analysis (RSA), plain radiographs (radiolucencies), and patient-reported outcome measures (PROMs). Methods Forty-seven patients (51 hips) agreed to participate in this prospective RSA study. All patients received a Taperloc stem. Tantalum beads were inserted into the femoral bone surrounding the stem to measure migration using RSA. RSA films, plain radiograph, and PROM follow-up were obtained immediately after surgery, 6 months, 1, 2, 3, and 5 years after surgery. Results The median (interquartile range) subsidence was 0.03 mm (−0.23 to 0.06) at 5 years, with no significant differences over time. Four outlier stems had >1.5 mm of subsidence by 1 year. No stem showed radiolucencies in more than 3 zones during the 5 years. All PROMs remained favorable at 5 years, suggesting an excellent outcome. There were no stems revised for mechanical loosening; 1 stem was revised for an infection. Conclusion After initial settling, the cementless tapered femoral stems in our series were stable. The 4 outlier stems with >1.5 mm of subsidence by 1 year remain stable at 5 years. RSA was the most sensitive method of detection for stems at greater risk for potential future failure. This report adds contributions to the positive results associated with this type of fixation. The results at 5 years showed excellent midterm survivorship in this cohort with a cementless tapered femoral component.
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precision of Radiostereometric Analysis rsa of acetabular cup stability and polyethylene wear improved by adding tantalum beads to the liner
Acta Orthopaedica, 2015Co-Authors: Audrey K Nebergall, Henrik Malchau, Kevin A Rader, Henrik Palm, Meridith E GreeneAbstract:Background and purpose — In traditional Radiostereometric Analysis (RSA), 1 segment defines both the acetabular shell and the polyethylene liner. However, inserting beads into the polyethylene liner permits employment of the shell and liner as 2 separate segments, enabling distinct Analysis of the precision of 3 measurement methods in determining femoral head penetration and shell migration.Patients and methods — The UmRSA program was used to analyze the double examinations of 51 hips to determine if there was a difference in using the shell-only segment, the liner-only segment, or the shell + liner segment to measure wear and acetabular cup stability. The standard deviation multiplied by the critical value (from a t distribution) established the precision of each method.Results — Due to the imprecision of the automated edge detection, the shell-only method was least desirable. The shell + liner and liner-only methods had a precision of 0.115 mm and 0.086 mm, respectively, when measuring head penetration....
Johan Karrholm - One of the best experts on this subject based on the ideXlab platform.
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wear measurements with use of Radiostereometric Analysis in total hip arthroplasty with obscured femoral head
Journal of Orthopaedic Research, 2020Co-Authors: Pererik Johanson, Bita Shareghi, Michael Eriksson, Johan KarrholmAbstract:Radiostereometric Analysis (RSA) has evolved as gold standard in the evaluation of wear and especially as regards novel hip implant materials. However, several cup shell materials and articulation types used in total hip arthroplasty (THA) cannot be studied due to poor radiographic visibility of the femoral head (FH). We addressed this problem with use of a point transfer function in the RSA software to indirectly measure FH translations with use of stem markers. In a base examination, the stem marker segment and cup center, as an approximation for the FH center position, were mathematically coupled. Thereafter, in subsequent examinations, we used the point transfer function to calculate FH positions from stem marker positions. To determine the variance of the difference of directly and indirectly measured FH positions, four stem marker configurations were studied in THAs with radiographically visible FHs. For the axis with least variance we also compared directly and indirectly measured translation up to 7 years. Finally, we applied the method in a ceramic-on-ceramic (COC) articulation and measured proximal translation up to 7 years and also estimated precision. Vertical translations had the smallest variation between measured and calculated FH position. Directly and indirectly measured vertical FH translation correlated well but indirect measurements had increased variance. Proximal steady-state penetration rate in uncemented COC THA was -0.003 (SD 0.021) mm/year with 99% precision along the vertical axis measuring 0.34 mm. The point transfer function can be used to measure proximal FH penetration, but with less precision than direct RSA.
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validation of gait Analysis with dynamic Radiostereometric Analysis rsa in patients operated with total hip arthroplasty
Journal of Orthopaedic Research, 2017Co-Authors: Roland Zugner, Roy Tranberg, Bita Shareghi, Vera Lisovskaja, Johan KarrholmAbstract:We simultaneously examined 14 patients with OTS and dynamic Radiostereometric Analysis (RSA) to evaluate the accuracy of both skin- and a cluster-marker models. The mean differences between the OTS and RSA system in hip flexion, abduction, and rotation varied up to 9.5° for the skin-marker and up to 11.3° for the cluster-marker models, respectively. Both models tended to underestimate the amount of flexion and abduction, but a significant systematic difference between the marker and RSA evaluations could only be established for recordings of hip abduction using cluster markers (p = 0.04). The intra-class correlation coefficient (ICC) was 0.7 or higher during flexion for both models and during abduction using skin markers, but decreased to 0.5-0.6 when abduction motion was studied with cluster markers. During active hip rotation, the two marker models tended to deviate from the RSA recordings in different ways with poor correlations at the end of the motion (ICC ≤0.4). During active hip motions soft tissue displacements occasionally induced considerable differences when compared to skeletal motions. The best correlation between RSA recordings and the skin- and cluster-marker model was found for studies of hip flexion and abduction with the skin-marker model. Studies of hip abduction with use of cluster markers were associated with a constant underestimation of the motion. Recordings of skeletal motions with use of skin or cluster markers during hip rotation were associated with high mean errors amounting up to about 10° at certain positions. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1515-1522, 2017.
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clinical evaluation of model based Radiostereometric Analysis to measure femoral head penetration and cup migration in four different cup designs
Journal of Orthopaedic Research, 2017Co-Authors: Bita Shareghi, Pererik Johanson, Johan KarrholmAbstract:In conventional Radiostereometric Analysis (RSA) implants with attached tantalum markers are frequently used, which may be difficult to visualize. This problem can be avoided with model-based RSA (MBRSA), but it is uncertain if this method has the same precision as marker-based RSA. We evaluated the influence of cup design for the precision of MBRSA in four uncemented cups to study if the design had any influence on the precision. Stereo radiographs were analyzed postoperatively (double-examinations) and after 2 years (single examinations). The difference between the double-examinations was used to compute the precision for the methods and for each type of implant. Femoral head penetration and cup translation up to 2 years were compared using marker-based RSA as reference. The precision of proximal penetration and migration measurements did not differ between the methods for Trilogy, TMT and ABG. For Ringloc design a poorer precision was observed using MBRSA. Comparison between the methods regarding proximal penetration and cup migration at 2 years did not differ for three of the designs (p = 0.12-0.91). However, for the group with porous plasma sprayed surface (Ringloc) a significant difference between the methods was observed (ppenetration <0.01 and pmigration <0.01). Poorer precision, different penetration and migration values at 2 years for one of the designs indicate that the resolution of MBRSA might vary depending on surface coating and implant geometry. Therefore, we conclude that the resolution of MBRSA has to be studied for each type of basic cup design. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:760-767, 2017.
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simultaneous measurements of knee motion using an optical tracking system and Radiostereometric Analysis rsa
Acta Orthopaedica, 2011Co-Authors: Roy Tranberg, Tuuli Saari, Roland Zugner, Johan KarrholmAbstract:Background and purpose Invasive methods are more reproducible and accurate than non-invasive ones when it comes to recording knee kinematics, but they are usually less accessible and less safe, mainly due to risk of infection. For this reason, non-invasive methods with passive markers are widely used. With these methods, varying marker sets based on a number of single markers, or sets of markers, known as clusters, are used to track body segments. We compared one invasive method—Radiostereometric Analysis—with a non-invasive method, an optical tracking system with 15 skin-mounted markers.Methods 9 subjects (10 knees) were investigated simultaneously with a dynamic RSA system and a motion-capture system while performing an active knee extension.Results For flexion/extension, there was good agreement on an individual basis and at the group level. For internal/external rotation, the group mean was fairly similar, up to 25 degrees of flexion. Recordings of abductions and/or adductions revealed a systematic me...
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the history and future of Radiostereometric Analysis
Clinical Orthopaedics and Related Research, 2006Co-Authors: Johan Karrholm, Richie Gill, Edward R ValstarAbstract:Roentgen stereophotogrammetry allows one to localize the position of an object in space using roentgen rays. For orthopaedic purposes it was developed 35 years ago by Goran Selvik, and since that time many investigators have refined the Radiostereometric calculations and evaluative software. Many uses and mathematical algorithms have been developed, and advancements in computer programs and digital radiography continue to expand its capabilities. Despite these advances, improvements in the technical accuracy and type of kinematic analyses possible have been relatively modest. However, Radiostereometric Analysis is now easier and less time consuming to use, with a resolution in clinical practice almost equal to what could only previously be obtained under ideal laboratory conditions. The ability to measure skeletal and implant movements with high resolution in vivo images was an important progressive step for the orthopaedic community. Radiostereometric Analysis has helped develop new fields in clinical orthopaedic research and continues to improve advancements in orthopaedic health care.
Stuart A Callary - One of the best experts on this subject based on the ideXlab platform.
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highly crosslinked polyethylene liners have negligible wear at 10 years a Radiostereometric Analysis study
Clinical Orthopaedics and Related Research, 2021Co-Authors: David G Campbell, Stuart A CallaryAbstract:BACKGROUND The introduction of crosslinked ultra-high molecular weight polyethylene (XLPE) acetabular liners has been very successful, with decreased wear and reduction in the rates of revision hip arthroplasties. XLPE is the preferred articulation for most surgeons; however, there are concerns about the long-term performance of XLPE liners created with different manufacturing processes, which may lead to time-dependent failure, including accelerated wear, after several years. QUESTIONS/PURPOSES (1) What is the amount and rate of wear during the first 10 years using Radiostereometric Analysis (RSA) measurements of patients who had THAs that included a second-generation XLPE bearing? (2) Does the rate of wear change after 5 years in situ? METHODS This is a brief follow-up of a previous RSA study. In that study, we prospectively enrolled 21 patients with osteoarthritis who underwent primary cementless THA with an XLPE acetabular liner (three cycles of 3Mrad annealed) and 32-mm articulation. That group represented 44% of the 48 THAs performed by the surgeon at the hospital where RSA was available; 16 had cemented hips, leaving 32 who were invited to participate in this study. Of those, 11 lived rurally and declined to participate, leaving 21 patients who were included in the initial study. Since then, three patients died, one developed dementia and could not participate, and one had revision THA for reasons other than wear, leaving 16 patients available for Analysis at 10 years. Tantalum markers were inserted during surgery, and all patients had RSA radiographs taken at 1 week, 6 months, and 1, 2, 5, and 10 years postoperatively. Femoral head penetration into the acetabular component was measured with RSA, including bedding-in during the first year and annual wear thereafter. RESULTS The median medial, proximal, anterior, two-dimensional (2D), and three-dimensional (3D) wear rates between 1 and 10 years were -0.001, 0.004, -0.012, 0.000, and 0.002 mm/year, respectively. No patient in this cohort had a proximal or 2D wear rate greater than 0.025 mm/year. The median proximal wear rate between 5 and 10 years (0.002 mm/year) was not greater than wear at 1 to 5 years (0.004 mm/year). CONCLUSION Femoral head penetration in this second-generation XLPE liner remained very low at 10 years and accelerated wear after 5 years in situ did not occur. Concerns about late-onset wear from oxidation of irradiated-annealed XLPE were not observed. The low level of wear remains encouraging for the future clinical performance of this material. LEVEL OF EVIDENCE Level II, therapeutic study.
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long term migration characteristics of the corail hydroxyapatite coated femoral stem a 14 year Radiostereometric Analysis follow up study
Archives of Orthopaedic and Trauma Surgery, 2020Co-Authors: Owain Critchley, Stuart A Callary, David G Campbell, Graham Mercer, Christopher WilsonAbstract:The magnitude and pattern of acceptable long-term migration of cementless femoral stems are not well understood. The Corail hydroxyapatite-coated cementless stem is a clinically successful and commonly used femoral stem with a long-term migration pattern not previously described in the literature. The aim of this study was to assess the long-term migration of the Corail hydroxyapatite-coated cementless stem using Radiostereometric Analysis (RSA) at 14-year follow-up, thereby establishing a benchmark acceptable long-term migration pattern for hydroxyapatite-coated cementless prostheses. A prospective cohort of 29 patients (30 hips) undergoing primary total hip arthroplasty for primary hip osteoarthritis were enrolled into a study to characterise the migration of the Corail cementless stem. A total of 13 patients (4 males, 9 females) with mean age 82 (range 68–92) underwent repeat RSA radiographs at minimum 10 years post-operation (mean 13.9 years, range 13.3–14.4). Subsidence of the stem was measured and compared to prior measurements taken at 6 months and 1, 2, and 6 years. None of the 13 patients have been revised. The migration at 6 months, 1 year, 2 years, and 6 years has been previously recorded. At mean 14-year follow-up, the cohort mean subsidence of the cementless stem was 0.70 mm (range − 0.06 to 3.61 mm). For each stem followed up at 6 months and 14 years, the mean subsidence over this period was 0.05 mm (range − 0.14 to 0.57 mm). There is no significant difference in mean subsidence at 6 months and 14 years (p = 0.43). The long-term pattern of the subsidence of the Corail femoral stem has not previously been described. Subsidence occurs within the first 6 months, after which there is persistent stabilisation of the implant to 14 years. This study provides a description of a long-term acceptable migration pattern to which new hydroxyapatite-coated cementless prostheses may be compared. II.
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the stability of the porous tantalum components used in revision tha to treat severe acetabular defects a Radiostereometric Analysis study
Journal of Bone and Joint Surgery American Volume, 2018Co-Authors: Stuart A Callary, Donald W Howie, Lucian B. Solomon, John M AbrahamsAbstract:Background The acetabular components used in revision total hip arthroplasty (THA) to treat severe acetabular bone defects have high rates of re-revision at mid to long-term follow-up. Early translation of acetabular components used in revision THA is a good predictor of later loosening, and Radiostereometric Analysis (RSA) is the most sensitive method to measure migration. The objectives of the present study were to use RSA to compare the migration of the porous tantalum acetabular components used to treat severe bone defects with the previously established acceptable proximal translation threshold of ≤1 mm within 2 years, and to determine the effect on migration of the addition of inferior screws through the component into the ischium or pubis. Methods RSA was utilized to measure the migration of 55 porous tantalum components used to treat severe acetabular defects (28 Paprosky IIIA, 27 Paprosky IIIB; 21 hips with pelvic discontinuity) at a mean follow-up of 4 years (range, 2 to 12 years). Results Forty-eight of the 55 components migrated less than the threshold that predicts later loosening (>1 mm) and 50 had not been re-revised at the time of the latest follow-up. Seven components, none of which had inferior screw fixation, exceeded the translation threshold. Of these, 6 were implanted to treat pelvic discontinuity. Of those 6 components, 5 were re-revised for loosening related to patient symptoms. At 2 years, the absolute median proximal translation of components with inferior screw fixation was |0.3| mm (range, |0.1| to |0.9| mm), compared with |0.4| mm (range, |0.03| to |16.4| mm) for those without inferior screws (p = 0.04). Conclusions As measured with use of RSA, the majority of porous tantalum acetabular components used in a revision THA to treat severe acetabular defects had acceptable early migration. This predicts good long-term survivorship of these components. The use of inferior screws further improved acetabular component fixation. Level of evidence Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
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low wear of a second generation highly crosslinked polyethylene liner a 5 year Radiostereometric Analysis study
Clinical Orthopaedics and Related Research, 2013Co-Authors: Stuart A Callary, John R Field, David G CampbellAbstract:A sequentially irradiated and annealed, second-generation highly crosslinked polyethylene (XLPE) liner was introduced clinically in 2005 to reduce in vivo oxidation. This liner design has also been shown to reduce wear in vitro when compared with conventional and first-generation crosslinked liners. To date, there is only one study reporting an in vivo wear rate of this liner at 5 years’ followup. However, that study used measurements made from plain radiographs, which have limited sensitivity, particularly when monitoring very low amounts of wear. What is the amount and direction of wear at 5 years using Radiostereometric Analysis (RSA) in patients who had THAs that included second-generation XLPE? We prospectively reviewed 21 patients who underwent primary cementless THA with the same design of XLPE acetabular liner and 32-mm articulation. Tantalum markers were inserted during surgery and all patients had RSA radiographs at 1 week, 6 months, and 1, 2, and 5 years postoperatively. Femoral head penetration within the acetabular component was measured with UmRSA® software. One patient died and two had incomplete radiographs leaving 18 radiographic series for Analysis. The mean amounts of proximal, two-dimensional, and three-dimensional head penetration between 1 week and 5 years were 0.018, 0.071, and 0.149 mm, respectively. The mean proximal, two-dimensional, and three-dimensional wear rates calculated between 1 year and 5 years were all less than 0.001 mm/year with no patient recording a wear rate of more than 0.040 mm/year. The head penetration of a second-generation XLPE liner remained low at 5 years and the wear rate calculated after the first year was low in all directions. This low level of wear remains encouraging for the future clinical performance of this material. Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.
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weight bearing induced displacement and migration over time of fracture fragments following split depression fractures of the lateral tibial plateau a case series with Radiostereometric Analysis
Journal of Bone and Joint Surgery-british Volume, 2011Co-Authors: Lucian B. Solomon, Stuart A Callary, Aaron W Stevenson, Margaret A Mcgee, Mellick J Chehade, Donald W HowieAbstract:We investigated the stability of seven Schatzker type II fractures of the lateral tibial plateau treated by subchondral screws and a buttress plate followed by immediate partial weight-bearing. In order to assess the stability of the fracture, weight-bearing inducible displacements of the fracture fragments and their migration over a one-year period were measured by differentially loaded Radiostereometric Analysis and standard Radiostereometric Analysis, respectively. The mean inducible craniocaudal fracture fragment displacements measured −0.30 mm (−0.73 to 0.02) at two weeks and 0.00 mm (−0.12 to 0.15) at 52 weeks. All inducible displacements were elastic in nature under all loads at each examination during follow-up. At one year, the mean craniocaudal migration of the fracture fragments was −0.34 mm (−1.64 to 1.51). Using Radiostereometric methods, this case series has shown that in the Schatzker type II fractures investigated, internal fixation with subchondral screws and a buttress plate provided adequate stability to allow immediate post-operative partial weight-bearing, without harmful consequences.
Henrik Malchau - One of the best experts on this subject based on the ideXlab platform.
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Radiostereometric Analysis of stability and inducible micromotion after locked lateral plating of distal femur fractures
Journal of Orthopaedic Trauma, 2020Co-Authors: Vincent P Galea, Henrik Malchau, Mina A Botros, Michael F Mctague, Michael T Weaver, Mark S Vrahas, Marilyn Heng, Charles R BragdonAbstract:OBJECTIVES To evaluate interfragmentary motion over 1 year after distal femoral fracture fixation using Radiostereometric Analysis (RSA). The secondary aim was to assess whether RSA data are consistent with diagnoses of nonunion. DESIGN Prospective cohort study. SETTING Level I urban trauma center. PATIENTS Sixteen patients between 22 and 89 years of age with distal femoral fracture (OTA/AO type 33). INTERVENTION All fractures were treated with a lateral locking plate, and tantalum markers were inserted into the main proximal and distal fracture fragments. RSA was performed at 2, 6, 12, 18, and 52 weeks postoperatively. Both unloaded and loaded RSA measurements were performed. MAIN OUTCOME MEASUREMENTS Unloaded fracture migration over time and inducible micromotion at the fracture site in the coronal plane were determined at each follow-up interval. RESULTS RSA precision in the coronal plane of interfragmentary motion over time and inducible micromotion were 1.2 and 0.9 mm in the coronal plane, respectively. Two cases required revision surgery for nonunion 1 year postoperatively. For cases of union, unloaded fracture migration stopped being detectable between 12 and 18 weeks, and inducible micromotion was no longer detectable by the 12-week visit. For cases of nonunion, both unloaded migration and inducible micromotion were detected throughout the study period. CONCLUSIONS RSA may be used to reliably assess distal femoral fracture healing. RSA revealed differences in cases of union and nonunion by 3 months and more consistently than traditional x-rays. LEVEL OF EVIDENCE Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.
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vitamin e diffused highly cross linked polyethylene in total hip arthroplasty at five years a randomised controlled trial using Radiostereometric Analysis
Journal of Bone and Joint Surgery-british Volume, 2017Co-Authors: Audrey K Nebergall, Henrik Malchau, Meridith E Greene, Mogens Berg Laursen, Poul Torben Nielsen, Anders TroelsenAbstract:Aims The objective of this five-year prospective, blinded, randomised controlled trial (RCT) was to compare femoral head penetration into a vitamin E diffused highly cross-linked polyethylene (HXLPE) liner with penetration into a medium cross-linked polyethylene control liner using Radiostereometric Analysis. Patients and Methods Patients scheduled for total hip arthroplasty (THA) were randomised to receive either the study E1 (32 patients) or the control ArComXL polyethylene (35 patients). The median age (range) of the overall cohort was 66 years (40 to 76). Results The five-year median (interquartile range) proximal femoral head penetration into the E1 was -0.05 mm (-0.13 to -0.02) and 0.07 mm (-0.03 to 0.16) for ArComXL. At three and five years, the penetration was significantly greater in the ArComXL group compared with the E1 group (p = 0.029 and p = 0.019, respectively). All patient-reported outcomes (PROs) improved significantly from the pre-operative interval compared with those at one year, and remained favourable at five years. There were no differences between the two groups at any interval. Conclusion The five-year results showed that E1 polyethylene does not wear more than the control, ArComXL. This is the longest-term RCT comparing the wear performance and clinical outcome of vitamin E diffused HXLPE with a previous generation of medium cross-linked polyethylene. Cite this article: Bone Joint J 2017;99-B:577–84.
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thirteen year evaluation of highly cross linked polyethylene articulating with either 28 mm or 36 mm femoral heads using Radiostereometric Analysis and computerized tomography
Journal of Arthroplasty, 2016Co-Authors: Audrey K Nebergall, Anders Troelsen, Henrik Malchau, Meridith E Greene, Harry E Rubash, Ola RolfsonAbstract:Abstract Background The objective of this 13-year prospective evaluation of highly cross-linked ultra high molecular weight polyethylene (HXLPE) was to (1) assess the long-term wear of HXLPE articulating with 2 femoral head sizes using Radiostereometric Analysis (RSA) and to (2) determine if osteolysis is a concern with this material through the use of plain radiographs and computerized tomography (CT). Methods All patients received a Longevity HXLPE liner with tantalum beads and either a 28-mm or 36-mm femoral head. Twelve patients (6 in each head size group) agreed to return for 13-year RSA, plain radiograph, and CT follow-up. The 1-year and 13-year plain radiographs as well as the CT scans were analyzed for the presence of osteolysis. Results The 13-year mean ± standard error steady-state wear was 0.05 ± 0.02 mm with no significant increase over time or between the 2 head size groups. Two patients' CT scans showed radiolucent regions in the acetabulum of 4.51 cm 3 and 11.25 cm 3 , respectively. In one patient, this area corresponded to a partially healed degenerative cyst treated with autograft during surgery. The second patient had an acetabular protrusio treated with autograft, and the CT scan revealed areas of remodeling of this graft. One patient's 13-year plain radiographs showed evidence of cup loosening and linear radiolucencies in zones 2 and 3. Conclusion There was no evidence of significant wear over time using RSA. The CT scans did not show evidence of osteolysis due to wear particles. These results suggest that this material has reduced wear compared to conventional polyethylene, irrespective of head size.
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five year experience of vitamin e diffused highly cross linked polyethylene wear in total hip arthroplasty assessed by Radiostereometric Analysis
Journal of Arthroplasty, 2016Co-Authors: Audrey K Nebergall, Anders Troelsen, Henrik Malchau, Harry E Rubash, Ola Rolfson, Meridith E GreeneAbstract:Abstract Background Vitamin E–diffused highly cross-linked polyethylene (VEPE) was developed to reduce oxidation without compromising mechanical strength. The purpose of this study was to evaluate VEPE in vivo using Radiostereometric Analysis (RSA) and patient-reported outcome measures (PROMs). Methods Fifty-one hips were enrolled. Each patient received a VEPE liner, a porous titanium shell, and an uncemented stem with a 32-mm cobalt–chrome femoral head. Tantalum beads were inserted into the VEPE to measure femoral head penetration using RSA. RSA radiographs and PROMs were obtained preoperatively immediately after surgery, 6 months, 1, 2, 3, and 5 years after surgery. Results Forty-seven hips returned at 3 years, and 42 hip at 5 years. The mean ± standard error of the mean proximal head penetration into the polyethylene was 0.06 ± 0.01 at 5 years. The amount of head penetration did not change significantly with increasing time in vivo. The mean ± standard error of the mean Harris Hip Score was 58 ± 2 preoperatively, which improved significantly to 93 ± 2 at 5 years (P Conclusion The head penetration into VEPE liners was low compared with non-VEPE at 5 years. After settling of the liners in the early period, no significant head penetration occurred from 2- to 5-year follow-up. All PROMs improved significantly from preoperative to postoperative and remained very favorable at 5 years. This study documents the longest-term evaluation of in vivo wear performance of VEPE.
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stable fixation of a cementless proximally coated double wedged double tapered femoral stem in total hip arthroplasty a 5 year Radiostereometric Analysis
Journal of Arthroplasty, 2016Co-Authors: Audrey K Nebergall, Anders Troelsen, Henrik Malchau, Harry E Rubash, Ola Rolfson, Meridith E GreeneAbstract:Abstract Background The objective of this 5-year prospective study of 51 hips was to assess migration of a cementless tapered femoral stem using Radiostereometric Analysis (RSA), plain radiographs (radiolucencies), and patient-reported outcome measures (PROMs). Methods Forty-seven patients (51 hips) agreed to participate in this prospective RSA study. All patients received a Taperloc stem. Tantalum beads were inserted into the femoral bone surrounding the stem to measure migration using RSA. RSA films, plain radiograph, and PROM follow-up were obtained immediately after surgery, 6 months, 1, 2, 3, and 5 years after surgery. Results The median (interquartile range) subsidence was 0.03 mm (−0.23 to 0.06) at 5 years, with no significant differences over time. Four outlier stems had >1.5 mm of subsidence by 1 year. No stem showed radiolucencies in more than 3 zones during the 5 years. All PROMs remained favorable at 5 years, suggesting an excellent outcome. There were no stems revised for mechanical loosening; 1 stem was revised for an infection. Conclusion After initial settling, the cementless tapered femoral stems in our series were stable. The 4 outlier stems with >1.5 mm of subsidence by 1 year remain stable at 5 years. RSA was the most sensitive method of detection for stems at greater risk for potential future failure. This report adds contributions to the positive results associated with this type of fixation. The results at 5 years showed excellent midterm survivorship in this cohort with a cementless tapered femoral component.
