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- Title:
The validity of a novel radiological method for measuring femoral stem version on anteroposterior radiographs of the hip after total hip arthroplasty.
- Document type:
- Controlled Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't; Validation Studies
- Author(s):
- Weber, M; Lechler, P; von Kunow, F; Völlner, F; Keshmiri, A; Hapfelmeier, A; Grifka, J; Renkawitz, T
- Abstract:
- Femoral stem version has a major influence on impingement and early post-operative stability after total hip arthroplasty (THA). The main objective of this study was to evaluate the validity of a novel radiological method for measuring stem version. Anteroposterior (AP) radiographs and three-dimensional CT scans were obtained for 115 patients (female/male 63/72, mean age 62.5 years (50 to 75)) who had undergone minimally invasive, cementless THA. Stem version was calculated from the AP hip radiograph by rotation-based change in the projected prosthetic neck-shaft (NSA*) angle using the mathematical formula ST = arcos [tan (NSA*) / tan (135)]. We used two independent observers who repeated the analysis after a six-week interval. Radiological measurements were compared with 3D-CT measurements by an independent, blinded external institute. We found a mean difference of 1.2° (sd 6.2) between radiological and 3D-CT measurements of stem version. The correlation between the mean radiological and 3D-CT stem torsion was r = 0.88 (p < 0.001). The intra- (intraclass correlation coefficient >= 0.94) and inter-observer agreement (mean concordance correlation coefficient = 0.87) for the radiological measurements were excellent. We found that femoral tilt was associated with the mean radiological measurement error (r = 0.22, p = 0.02). The projected neck-shaft angle is a reliable method for measuring stem version on AP radiographs of the hip after a THA. However, a highly standardised radiological technique is required for its precise measurement.
- Journal title abbreviation:
- Bone Joint J
- Year:
- 2015
- Journal volume:
- 97-B
- Journal issue:
- 3
- Pages contribution:
- 306-11
- Language:
- eng
- Fulltext / DOI:
- doi:10.1302/0301-620X.97B3.34618
- Pubmed ID:
- http://view.ncbi.nlm.nih.gov/pubmed/25737512
- Print-ISSN:
- 2049-4394
- TUM Institution:
- Institut für Medizinische Statistik und Epidemiologie
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