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- Bragdon, C. R., et al.
(författare)
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Experimental assessment of precision and accuracy of radio stereometric analysis for the determination of polyethylene wear in a total hip replacement model
- 2002
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Ingår i: Journal of Orthopaedic Research. ; 20:4, s. 688-695
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to develop and testa phantom model based on actual total hip replacement (THR) components to simulate the true penetration of the femoral h cad resulting fro in polyethylene car, This Model was used to Study both the accuracy and the precision of radiostereometric analysis, RSA, in measuring wear. We also used this model to evaluate optimum tantalum bead configuration for this particular cup design when used in a clinical setting. A physical model of a total hip replacement (a phantom) was constructed which Could simulate progressive. three-dimensional (3-D) penetration of the femoral head into the polyethylene component of a THR. Using it coordinate Measuring machine (CMM) the positioning of the femoral head using the phantom was measured to be accurate to within 7 mum The accuracy and precision of an RSA analysis system was determined from five repeat examinations of the phantom using various experimental set-ups of the phantom. The accuracy of the radiostereometric analysis, in this optimal experimental set-up studied was 33 mum for the medial direction, 22 mum for the superior direction, 86 mum for the posterior direction and 55 mum for the resultant 3-D vector length. The corresponding precision at the 95% confidence interval of the test results for repositioning the phantom five times. measured 8.4 mum for the medial direction, 5.5 mum for the superior direction. 16.0 mum for the posterior direction. and 13 5 mum for the resultant 3-D vector length. This in vitro model is proposed as a useful tool for developing a standard for the evaluation of radiostereometric and other radiographic methods used to measure in vivo wear. (C) 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd, All rights reserved.
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| 2. |
- Ioppolo, J. L., et al.
(författare)
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Kinematic joint measurement RSA flouroscopy
- 2004
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Ingår i: Proc. Ann. Meet. Aust. Coll. Phys. Scient. Eng. Med. (WA Branch). ; , s. 7-7
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 3. |
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| 4. |
- Borlin, Niclas, et al.
(författare)
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RSA wear measurements with or without markers in total hip arthroplasty
- 2006
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Ingår i: Journal of Biomechanics. ; 39:9, s. 1641-1650
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Tidskriftsartikel (refereegranskat)abstract
- Novel algorithms for radiostereometric (RSA) measurements of the femoral head and metal-backed, hemi-spherical cups of a total hip replacement are presented and evaluated on phantom images and clinical double examinations of 20 patients. The materials were analysed with classical RSA and three novel algorithms: (1) a dual-projection head algorithm using the outline of the femoral head together with markers in the cup; (2) a marker-less algorithm based on measurements of the outline of the femoral head, the cup shell and opening circle of the cup; and (3) a combination of both methods. The novel algorithms improve current, marker-based, RSA measurements, as well as allows studies without marked cups. This opens the possibility of performing wear measurements on larger group of patients, in clinical follow-ups, even retrospective studies. The novel algorithms may help to save patient data in current RSA studies lost due to insufficiently marked cups. Finally, the novel algorithms simplify the RSA procedure and allow new studies without markers, saving time, money, and reducing safety concerns. Other potential uses include migration measurements of re-surfacing heads and measuring spherical sections as implant landmarks instead of markers. (c) 2005 Elsevier Ltd. All rights reserved.
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| 10. |
- Ioppolo, J., et al.
(författare)
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Validation of a low-dose hybrid RSA and fluoroscopy technique : Determination of accuracy, bias and precision
- 2007
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Ingår i: Journal of Biomechanics. ; 40:3, s. 686-692
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Tidskriftsartikel (refereegranskat)abstract
- Analyzing skeletal kinematics with radiostereometric analysis (RSA) following corrective orthopedic surgery allows the quantitative comparison of different implant designs. The purpose of this study was to validate a technique for dynamically estimating the relative position and orientation of skeletal segments using RSA and single plane X-ray fluoroscopy. Two micrometer-based in vitro phantom models of the skeletal segments in the hip and knee joints were used. The spatial positions of tantalum markers that were implanted into each skeletal segment were reconstructed using RSA. The position and orientation of each segment were determined in fluoroscopy images by minimizing the difference between the markers measured and projected in the image plane. Accuracy was determined in terms of bias and precision by analyzing the deviation between the applied displacement protocol and measured pose estimates. Measured translational accuracy was less than 100 mu m parallel to the image plane and less than 700 mu m in the direction orthogonal to the image plane. The measured rotational error was less than 1 degrees. Measured translational and rotational bias was not statistically significant at the 95% level of confidence. The technique allows real-time kinematic skeletal measurements to be performed on human subjects implanted with tantalum markers for quantitatively measuring the motion of normal joints and different implant designs. (c) 2006 Elsevier Ltd. All rights reserved.
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