| 1. |
- Bragdon, Charles R, 1959, et al.
(author)
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Comparison of two digital radiostereometric analysis methods in the determination of femoral head penetration in a total hip replacement phantom
- 2004
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In: J Orthop Res. - : Wiley. - 0736-0266. ; 22:3, s. 659-64
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Journal article (peer-reviewed)abstract
- Radiostereometric analysis (RSA) has been used extensively to evaluate the magnitude and direction of penetration of the femoral head into the acetabular component of a total hip replacement as a result of polyethylene wear and creep. The accuracy and precision of an RSA study depends on several factors, including the radiographic technique, the analytical software, and the positioning of the tantalum markers. This study had three sequential purposes. First, an in vitro phantom model was used to quantify the accuracy and precision of digital images versus conventional radiography in RSA measurements of penetration of the femoral head into the acetabular shell in a total hip replacement. The Umea RSA software package was used for analysis of both the conventional films, which were digitized at a resolution of 300 DPI, and digital radiographs, which were converted from a DICOM format at a resolution of 218 DPI. Digital radiography was found to be superior. Next, two methods of RSA analysis currently in use for determining femoral head penetration into polyethylene of total joint replacements were compared. Using the phantom model, we compared the Umea RSA system (Biomedical Innovations AB) to the RSA-CMS (RSA Clinical Measurement Solution) and in both cases used the digital radiographs. The Umea RSA system was found to be superior. Finally, two methods of marking the position of the acetabular component with tantalum beads were compared: one in which beads were inserted into previously described towers protruding from the back of the acetabular shell and another in which beads were placed into the peripheral flange of the polyethylene liner using the Umea RSA analysis system of the digital radiographs. The results using the two marker configurations were similar.
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| 2. |
- Bojan, Alicja J., 1980, et al.
(author)
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Three-dimensional bone-implant movements in trochanteric hip fractures. Precision and accuracy of radiostereometric analysis in a phantom model.
- 2015
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In: Journal of orthopaedic research : official publication of the Orthopaedic Research Society. - : Wiley. - 1554-527X. ; 33:5, s. 705-11
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Journal article (peer-reviewed)abstract
- The accuracy and precision of RSA was evaluated in the experimental study of screw cut-out complication after fixation of trochanteric fractures. A plastic bone model of a two-part trochanteric fracture was constructed with a Gamma nail implant incorporating RSA markers. The femoral head fragment was attached to a separate rotational table and the femoral shaft was mounted on the micrometer. Three main motions were simulated: femoral head translation and rotation along the axis of the lag screw and fracture fragment translation along anatomical axes. Accuracy and precision were determined according to ISO 16087 and ASTM standard F2385-04. Translations along the lag screw axis were measured with a precision within±0.14mm and an accuracy within±0.03mm. With simultaneous translations along all three anatomical axes, lowest precision was measured for the x-axis (±0.29mm, 0.07mm respectively), but improved when analyzed as a vector (±0.08mm, 0.03mm). The precision and accuracy of femoral head rotations were within 0.5° and 0.18°, respectively. The resolution of the RSA method tested in this model was high, though it varied depending on the type of analyzed motion. This information is valuable when selecting and interpreting outcome parameters evaluating implant migration and osteosynthesis stability in future clinical RSA studies. This article is protected by copyright. All rights reserved.
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| 3. |
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| 4. |
- Bragdon, Charles R, 1959, et al.
(author)
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Comparison of femoral head penetration using RSA and the Martell method
- 2006
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In: Clin Orthop Relat Res. - 0009-921X. ; 448, s. 52-7
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Journal article (peer-reviewed)abstract
- Radiostereometry has high precision and accuracy measuring polyethylene wear in total hip arthroplasty but requires a specialized setup. The Martell method is simpler and can be used on larger populations. The hypothesis that the radiostereometry analysis and the Martell analysis would yield comparable wear data from the same group of patients having total hip arthroplasty was tested. A group of twenty-five total hip arthroplasty patients who had both radiostereometry and standard anterior-posterior pelvic and cross-table lateral radiographs of sufficient quality for analysis were identified. The films were taken at postoperative periods of 6 weeks, 1 year, 2 years, and 5 years. Femoral head penetration was measured by both methods at each time point. The median penetration rates measured by each method decreased over time. Penetration results were affected by method of analysis, time, and dimension, with greater penetration for Martell compared with radiostereometry at each time point, greater penetration with increasing time for each method, and larger three-dimensional magnitude compared with two-dimensional analysis. LEVEL OF EVIDENCE: Case series Level IV. See Guidelines for Authors for a complete description of levels of evidence.
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| 5. |
- Bragdon, Charles R, 1959
(author)
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Evaluation of methods of measuring wear of polyethylene acetabular components intotal hip arthroplasty
- 2004
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Doctoral thesis (other academic/artistic)abstract
- Background: The introduction of highly cross-linked, wear resistant polyethylene acetabularcomponents for clinical use in total hip replacements has intensified the interest in and need for highlyaccurate methods of measuring wear from clinical radiographs. There are several methods currentlyavailable for measuring the relative displacement of the femoral head into the acetabular componentresulting from the combination of plastic deformation and wear of the polyethylene bearing surface.However, there is no standard method available for evaluating the accuracy and precision of thesevarious methods and therefore no way of objectively comparing them. This thesis was designed todevelop an experimental standard practice for this purpose. The second purpose of the thesis was toperform two clinical studies designed to evaluate wear of polyethylene using different methods as wellas evaluate various parameters which may affect the quality of the calculated results.Specific aim: The goal of this research thesis was to explore a variety of variables and conditions whichmay affect a clinical radiographic study of femoral head penetration by first developing and using aphantom model of a total hip replacement and ultimately by evaluating two series of clinical radiographsfor two groups of patients who have received total hip replacements.Method: A physical hip model which used actual THR components was constructed which couldsimulate three dimensional migrations of the femoral head into the acetabular component due to creepand wear of the polyethylene component. A displacement protocol was developed consisting ofseventeen steps designed to simulate the three dimensional magnitude of femoral head displacementknown to occur in vivo. This phantom was used for the three research papers which evaluated, underideal circumstances, several variables known to affect RSA and non-RSA radiographic studies.The first clinical study compared the results of two methods of measuring femoral head penetrationusing the same group of THR patients. The second clinical study compared the results using radiographstaken with the patients standing vs. lying supine.Results: Using the phantom, change from conventional hard copy radiographs to digital DICOM imageswas validated. The results using the UmRSA software were superior to those using the RSA-CMSmethod. Different bead placement methods and configurations were validated. In further development ofthe Hip Analysis Suite program, the results using oblique projection of the hip were comparable to theuse of the standard A/P and lateral films under ideal experimental conditions. While the clinical resultsusing the Hip Analysis Suite software were similar to those obtained using the UmRSA software interms of the pattern of wear over time, the magnitude of the measured femoral head penetration was30% higher. In an RSA study of femoral head penetration, the evaluation of supine vs. standingradiographs showed comparable results.Conclusions: The results of this thesis enable comparisons of the effect of changing differentparameters which can be useful in developing an experimental design. The phantom model has to be auseful tool in evaluating and developing analysis software, validation of new research centers, and as atraining tool for new users. The clinical studies provide insight into the relative comparison of twoanalysis methods under practical conditions and have examined the need and practicality of requiringstanding radiographs for clinical wear studies.
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| 6. |
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| 7. |
- Bragdon, Charles R, 1959, et al.
(author)
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Standing versus supine radiographs in RSA evaluation of femoral head penetration
- 2006
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In: Clin Orthop Relat Res. - 0009-921X. ; 448, s. 46-51
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Journal article (peer-reviewed)abstract
- Evaluation of polyethylene acetabular component wear in total hip arthroplasties commonly is performed using serial radiographs of the hip by measuring the change in the location of the center of the femoral head in relation to the acetabular component. Of the different methods currently used for this purpose, radiostereometric analysis (RSA) is considered the most accurate and precise. In all such radiographic studies, it is assumed the femoral head is seated into the deepest portion of the acetabular component during all radiographic examinations. Although most radiographs used for wear measurements are taken with the patient supine, we questioned whether standing radiographs, with substantial joint load, are better suited for these measurements. We evaluated two groups of patients having total hip arthroplasty who had radiostereometric radiographs taken in supine and standing positions. The average femoral head penetration that occurred between the 6-month and 2-year time interval was measured with radiographs taken in the standing or supine position. We found no difference between the average total femoral head penetration when using supine or standing radiographs.
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| 8. |
- Goldvasser, Dov, et al.
(author)
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A New Technique for Measuring Wear in Total Hip Arthroplasty Using Computed Tomography
- 2012
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In: The Journal of Arthroplasty. - : Elsevier. - 0883-5403 .- 1532-8406. ; 27:9, s. 1636-1640
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Journal article (peer-reviewed)abstract
- Accurately estimating polyethylene wear in 3 dimensions, without the need for additional procedures or equipment, is of significant interest. We investigated the use of a high-resolution clinical computed tomographic (CT) scanner to estimate femoral head displacement relative to the cup as an indirect method of estimating polyethylene wear. A hip phantom was used to simulate the 3-dimensional displacement of a femoral head. The phantom was imaged in a high-resolution CT scanner. The mean difference between the true phantom displacement as positioned by micrometers and the calculated displacement based on the CT images was as follows: for the x-axis, 0 mm (SD, 0.213; SE, 0.058); y-axis, 0.039 mm (SD, 0.035; SE, 0.026); and z-axis, 0.039 mm (SD, 0.051; SE, 0.020).
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| 9. |
- Goldvasser, Dov, et al.
(author)
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In vivo and ex vivo measurement of polyethylene wear in total hip arthroplasty
- 2014
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In: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 85:3, s. 271-275
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Journal article (peer-reviewed)abstract
- Background - Determination of the amount of wear in a polyethylene liner following total hip arthroplasty (THA) is important for both the clinical care of individual patients and the development of new types of liners. Patients and methods - We measured in vivo wear of the polyethylene liner using computed tomography (CT) (obtained in the course of regular clinical care) and compared it to coordinate-measuring machine (CMM) readings. Also, changes in liner thickness of the same retrieved polyethylene liner were measured using a micrometer, and were compared to CT and CMM measurements. The distance between the centers of the acetabular cup and femoral head component was measured in 3D CT, using a semi-automatic analysis method. CMM readings were performed on each acetabular liner and data were analyzed using 3D computer-aided design software. Micrometer readings compared the thickest and thinnest regions of the liner. We analyzed 10 THA CTs and retrievals that met minimal requirements for CT slice thickness and explanted cup condition. Results - For the 10 cups, the mean difference between the CT readings and the CMM readings was -0.09 (-0.38 to 0.20) mm. This difference was not statistically significant (p = 0.6). Between CT and micrometer, the mean difference was 0.11 (-0.33 to 0.55) mm. This difference was not statistically significant (p = 0.6). Interpretation - Our results show that CT imaging is ready to be used as a tool in clinical wear measurement of polyethylene liners used in THA.
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| 10. |
- Hussey, Daniel K, et al.
(author)
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Scoring the Current Risk Stratification Guidelines in Follow-up Evaluation of Patients After Metal-on-Metal Hip Arthroplasty: A Proposal for a Metal-on-Metal Risk Score Supporting Clinical Decision-Making.
- 2016
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In: The Journal of bone and joint surgery. American volume. - 1535-1386. ; 98:22, s. 1905-1912
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Journal article (peer-reviewed)abstract
- In the follow-up evaluation of patients with metal-on-metal (MoM) hip replacements, current evidence suggests that orthopaedic surgeons should avoid reliance on any single investigative tool. Current risk stratification guidelines can be difficult to interpret because they do not provide guidance when there are several risk factors in different groups (high and low risk). To improve the clinical utility of risk stratification guidelines, we designed a scoring system to assess the risk of revision.The study population consisted of 1,709 patients (1,912 hips) enrolled in a multicenter follow-up study of a recalled MoM hip replacement. Eleven scoring criteria were determined on the basis of existing follow-up algorithm recommendations and consisted of patient-related factors, symptoms, clinical status, implant type, metal ion levels, and radiographic imaging results. Forward stepwise logistic regression was conducted to determine the minimum set of predictive variables for the risk of revision and to assign variable weights. The MoM risk score for each hip was then created by averaging the weighted values of each predictive variable.Receiver operating characteristic curve analysis yielded good discrimination between all revised and unrevised hips, with an area under the curve of 0.82 (p < 0.001). The odds of revision for the group with a high MoM risk score were increased by 5.8-fold (95% confidence interval [CI], 3.1 to 11.0) relative to the moderate risk group and by 21.8-fold (95% CI, 9.9 to 48.0) compared with the low risk group.Although the use of MoM hip arthroplasty has been limited since 2010, we continue to be faced with the follow-up and risk assessment of thousands of patients who have not had a revision. As more knowledge about risk stratification is gained, the complexity of the algorithms is expected to increase. We propose the use of the MoM risk score as a tool to aid in the clinical decision-making process.Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
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| 11. |
- Malchau, Henrik, 1951, et al.
(author)
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The stepwise introduction of innovation into orthopedic surgery: the next level of dilemmas.
- 2011
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In: The Journal of arthroplasty. - : Elsevier BV. - 1532-8406 .- 0883-5403. ; 26:6, s. 825-31
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Journal article (peer-reviewed)abstract
- The optimum method for the appropriate introduction of innovative technologies into orthopedics is a vital but vexing issue. Compromises in the introduction process are driven by (a) the magnitude of the problem addressed (incidence and severity), (b) the advantages and risks of the proposed solution, and (c) the "universal dilemma," meaning the inherent "gap" between all the nonhuman supporting data and the unknowns of both efficacy and long-term safety in large human usage over many years. Drawing on the data generated and the actual decision tree used in the introduction of a new highly cross-linked polyethylene as a case study, this article illustrates these "subsequent dilemmas."
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| 12. |
- Nebergall, Audrey, et al.
(author)
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Stable fixation of an osseointegated implant system for above-the-knee amputees.
- 2012
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In: Acta orthopaedica. - : Medical Journals Sweden AB. - 1745-3682 .- 1745-3674. ; 83:2, s. 121-128
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Journal article (peer-reviewed)abstract
- Background and purpose Rehabilitation of patients with transfemoral amputations is particularly difficult due to problems in using standard socket prostheses. We wanted to assess long-term fixation of the osseointegrated implant system (OPRA) using radiostereometric analysis (RSA) and periprosthetic bone remodeling. Methods 51 patients with transfemoral amputations (55 implants) were enrolled in an RSA study. RSA and plain radiographs were scheduled at 6 months and at 1, 2, 5, 7, and 10 years after surgery. RSA films were analyzed using UmRSA software. Plain radiographs were graded for bone resorption, cancellization, cortical thinning, and trabecular streaming or buttressing in specifically defined zones around the implant. Results At 5 years, the median (SE) migration of the implant was -0.02 (0.06) mm distally. The rotational movement was 0.42 (0.32) degrees around the longitudinal axis. There was no statistically significant difference in median rotation or migration at any follow-up time. Cancellization of the cortex (plain radiographic grading) appeared in at least 1 zone in over half of the patients at 2 years. However, the prevalence of cancellization had decreased by the 5-year follow-up. Interpretation The RSA analysis for the OPRA system indicated stable fixation of the implant. The periprosthetic bone remodeling showed similarities with changes seen around uncemented hip stems. The OPRA system is a new and promising approach for addressing the challenges faced by patients with transfemoral amputations.
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