Seemingly isolated greater trochanter fractures do not exist Poster No.: B-0950 Congress: ECR 2012 Type: Scientific Paper Authors: D. Dunker, J. H. Göthlin, M. Geijer ; Gothenburg/SE, Lund/SE Keywords: Musculoskeletal bone, MR, CT, Plain radiographic studies, Diagnostic procedure, Trauma, Osteoporosis DOI: 10.1594/ecr2012/B-0950 1 1 2 1 2 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 12
Purpose Since Armstrong published a radiograph of an avulsion fracture of the greater 1 traochanter it has been taken for granted that most of the radiographically diagnosed avulsions were, indeed, isolated. Computed tomography and especially magnetic resonance imaging has proved the diagnosis "isolated avulsion fracture of the greater 2 trochanter" to be uncommon. In cases with avulsions of the greater trochanter it is important establish whether a trochanteric extension is present and in such a case to demonstrate its extent as it may 2 influence the choice of treatment. The purpose of the current study was to assess the frequency and extent of seemingly isolated fractures of the greater trochanter as well as observer agreements in radiography, computed tomography (CT) and magnetic resonance imaging (MRI) of such fractures in a material of radiographically occult hip fractures. Methods and Materials Paitients with clinically suspected hip fracture after trauma during 2006-2008, with normal or equivocal radiography and subsequent CT or MRI, were retrospectively collected from Skåne University Hospital, Lund and Sahlgrenska University Hospital, Mölndal. A review with inter observer variance was performed in 373 patients with initial radiography followed by CT (n=232) or MRI (n=170), thus were 29 patients examined by both CT and MRI. Three reviewers with varying experience; a resident, a specialist in general radiology and a specialist in musculoskeletal radiology, scored extracapsular fractures as either complete trochanteric, avulsion of the greater trochanter with incomplete trochanteric extension or isolated avulsion of the greater trochanter. Observer variation was quantified 3 using linear Kappa statistics. Results The fractures were classified as definite, suspect or equivocal, or no fracture. There was total agreement between the three observers regarding the existence or not of extracapsular fractures in 77% at radiography, 90% at CT and 95% at MRI. Page 2 of 12
When classifying the cases as having a greater trochanteric avulsion fracture there was 82% agreement for radiography, 93% for CT and 84% for MRI, (Kappa value=0.61-0.92, substantial to near perfect). There was near perfect agreement on trochanteric fractures on MRI, even if all avulsions were not seen. However, there was no isolated avulsion fracture noted. Images for this section: Page 3 of 12
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Fig. 1: Male, age 83. Lateral cortical break in the greater trochanter. Page 5 of 12
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Fig. 2: Same patient as above, side projection. The avulsion of the greater trochanter is clearly demonstrated as a dorsal cortical break. Fig. 3: Same patient as above, coronal CT view. Cortical interruption in the greater trochanter but no signs of fracture in the inter-trochanteric region or in the medial aspect of the femur. Page 7 of 12
Fig. 4: Male, age 91. Cortical break with a slight dislocation of the tip of the greater trochanter. Page 8 of 12
Fig. 5: Same patient as above. Coronal T1 weighted MRI shows a dense line in the intertrochanteric region, assessed as a trochanteric fracture, leading to surgical treatment with a dynamic hip screw. Page 9 of 12
Fig. 6: Male, age 78. A cortical break is visible in the lateral aspect of the greater trochanter, assessed as an isolated fracture of the greater trochanter. Page 10 of 12
Fig. 7: Same patient as above. Coronal T1 weighted MRI shows a fracture extension in the right femur, assessed as a trochanteric fracture, leading to surgical treatment with internal fixation. Page 11 of 12
Conclusion Inter-observer variation was fairly good in diagnosing fractures at radiography but obviously better for CT (avulsions) and MRI (trochanter fractures). "Seemingly isolated fractures of the greater trochanter" always have a trochanteric extension, at least demostrated as "bone bruise". CT and radiography are often adequate in diagnosing avulsion fractures of the greater trochanter but not the trochanteric extension. MRI is superior to radiography and CT in demonstrating the existence and extension of trochanter fractures. References 1. 2. 3. Armstrong G E. Isolated fractures of the great trochanter. Ann Surg (1907); 46(2):292-297 Omura T. et al. Evaluation of isolated fractures of the greater trochanter with magnetic resonance imaging. Arch Orthop Trauma Surg (2000); 120 :195-197 Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics (1977); 33:159-74 Personal Information Page 12 of 12