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- 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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- 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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- Rohrl, S. M., et al.
(författare)
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Porous-coated cups fixed with screws: a 12-year clinical and radiostereometric follow-up study of 50 hips
- 2006
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Ingår i: Acta Orthop. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 77:3, s. 393-401
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Excellent mid-term results have stimulated the use of hemispherical porous-coated cups in hip replacement. With longer follow-up, there have been problems related to polyethylene wear and liner fixation, and osteolysis has been documented in reports of selected cases. We evaluated the clinical and radiographic results of 50 patients followed for 12 years. PATIENTS AND METHODS: 58 consecutive patients (58 hips), mean age 55 years, were operated with Harris-Galante (HG) I or II cups using line-to-line fit and additional screw fixation. Polyethylene linersgamma-sterilized in air and 32-mm ceramic heads were used. 8 patients died within 12 years, leaving 50 patients with a complete 12 year follow-up. 23 of the cups were also evaluated with radiostereometry (RSA) for migration, liner stability, and wear. RESULTS: All metal shells were still in situ after 12 years. 4 hips had been revised due to femoral loosening. In these revisions, the liner had been exchanged due to wear and/or instability, resulting in a cup survival rate of 89%. 28 cups displayed osteolytic lesions, mainly in relation to screws. RSA revealed minimum translations, but in many cases there were pronounced liner rotations suggesting unstable liners within the metal shell. The annual proximal wear was 0.09 mm and the three-dimensional wear was 0.16 mm. INTERPRETATION: RSA can predict the long-term performance of cup fixation. Low migration during the initial years after implantation indicates excellent long-term results regarding fixation of the metal shell. The main problem with this design appears to be liner instability and osteolysis, factors that are probably interrelated. Because these phenomena are clinically silent, we recommend regular follow-up of patients with HG cups to avoid sudden loosening and complicated revisions.
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