The morphology of the proximal femur in the very elderly

  • H.D. Veldman

Abstract

Introduction. The population of the very elderly (i.e. ≥80 years of age) is growing rapidly due to demographic changes, an increased life expectancy, in particular. As a consequence, a 170% increase in the number of performed total hip arthroplasties (THAs) is projected for the next decades. Previous studies described the age-related changes in the morphology of the proximal femur, however, almost exclusively in subjects <80 years of age and using 2D X-rays. In THA the emphasis lies on reconstruction of the center of rotation (CoR) in order to preserve leg length, leg rotation and muscle tension (more precise: lever arm). The present study focuses on the reconstruction of the center of rotation (CoR) in the very elderly, with emphasis on the neck-shaft angle (NSA), the femoral neck anteversion angle (FNAA) and the mediolateral offset (ML offset). Furthermore, the effect of patient demographics such as gender, length and weight on the internal and external morphology of the proximal femur, the relationships between dimensions and angles on the proximal femur, and the effect of the internal morphology of the femoral canal on parameters describing the external geometry of the proximal femur were investigated. Methods. Ninety very elderly subjects (avg. 84.2 ± 3.6 years, range 80-105 years, 50M/40F) got a high-resolution CT-scan of their right femur (voxel size 1x1x1mm). Cortical bone models were derived from these scans using a specialized threshold algorithm in Materialise Mimics v10 and were further processed in Inus Technology Rapidform 2006. In order to classify the proximal femoral canal shape in stovepipe, normal or champagne flute the canal flare index (CFI) was measured according to Noble et al. Results. Compared to previous studies, the mean NSA (125.1 ± 5.5) and FNAA (10.0 ± 5.6) values found in the present study did not show notable differences. Based on the coronal CFI, the studied femora can be divided into stovepipe (23.3%) and non-stovepipe (76.7%). This percentage of stovepipe shaped proximal femoral canals is high compared to literature about younger populations. There are no differences in the external geometry between femora with a stovepipe or a non-stovepipe shaped canal. Furthermore, the FHD and the CoR-LTabsolute proved to be positively correlated (r=0.449) in the current study, the CoR-LTabsolute/FHD-ratio showed to be 1.17. The distance between the lesser trochanter and the center of rotation was both absolute (59.54 ± 5.76mm vs. 54.85 ± 6.31mm) and vertical (44.37 ± 6.77mm vs. 38.95 ± 7.41mm) larger in males than in females. Discussion. Based on the current study, no alternations in the external geometry of the current hip stem have to be made for an optimal elderly hip stem. However, due to advanced osteoporosis, this population of very elderly subjects contained more stovepipe shaped proximal canals based on their CFI, than younger populations. This has implications for hip stem design in the elderly. Namely, the proximal canal in which the hip stem is fixated is widened, while the external morphology remains the same. A hip stem with a thicker part for fixating in the shaft and the same external features as the currently used hip stem seems thus optimal in the very elderly (≥80yrs). Furthermore, a new equation for determining the head height, based on the diameter of the femoral head is suggested, which may be useful in hemiarthroplasty.

References

Verhaar J. Meer inzicht in kwaliteit van orthopedische zorg. LROI-Rapportage. 2012.

Polishchuk DL, Patrick DA, Jr., Gvozdyev BV, Lee JH, Geller JA, Macaulay W. Predicting femoral head diameter and lesser trochanter to center of femoral head distance: a novel method of templating hip hemiarthroplasty. J Arthroplasty. 2013 Oct;28(9):1603-7.

Shon WY, Yun HH, Yang JH, Song SY, Park SB, Lee JW. The use of the posterior lesser trochanter line to estimate femoral neck version: an analysis of computed tomography measurements. J Arthroplasty. 2013 Feb;28(2):352-8.

Hofmann AA, Bolognesi M, Lahav A, Kurtin S. Minimizing leg-length inequality in total hip arthroplasty: use of preoperative templating and an intraoperative x-ray. Am J Orthop (Belle Mead NJ). 2008 Jan;37(1):18-23.

Noble PC, Alexander JW, Lindahl LJ, Yew DT, Granberry WM, Tullos HS. The anatomic basis of femoral component design. Clin Orthop Relat Res. 1988 Oct(235):148-65.

Mahaisavariya B, Sitthiseripratip K, Tongdee T, Bohez EL, Vander Sloten J, Oris P. Morphological study of the proximal femur: a new method of geometrical assessment using 3-dimensional reverse engineering. Med Eng Phys. 2002 Nov;24(9):617-22.

Adam F, Hammer DS, Pape D, Kohn D. The internal calcar septum (femoral thigh spur) in computed tomography and conventional radiography. Skeletal Radiol. 2001 Feb;30(2):77-83. 139

Anastopoulos G, Chissas D, Dourountakis J, Ntagiopoulos PG, Magnisalis E, Asimakopoulos A, et al. Computer-assisted three-dimensional correlation between the femoral neck-shaft angle and the optimal entry point for antegrade nailing. Injury. 2010 Mar;41(3):300-5.

Dy CJ, Schroder SJ, Thompson MT, Alexander JW, Noble PC. Etiology and severity of impingement injuries of the acetabular labrum: what is the role of femoral morphology? Orthopedics. 2012 Jun;35(6):e778-84.

Noble PC, Box GG, Kamaric E, Fink MJ, Alexander JW, Tullos HS. The effect of aging on the shape of the proximal femur. Clin Orthop Relat Res. 1995 Jul(316):31-44.

Rubin PJ, Leyvraz PF, Aubaniac JM, Argenson JN, Esteve P, de Roguin B. The morphology of the proximal femur. A three-dimensional radiographic analysis. J Bone Joint Surg Br. 1992 Jan;74(1):28-32.

Maruyama M, Feinberg JR, Capello WN, D’Antonio JA. The Frank Stinchfield Award: Morphologic features of the acetabulum and femur: anteversion angle and implant positioning. Clin Orthop Relat Res. 2001 Dec(393):52-65.

Sugano N, Noble PC, Kamaric E. Predicting the position of the femoral head center. J Arthroplasty. 1999 Jan;14(1):102-7.

Gulan G, Matovinovic D, Nemec B, Rubinic D, Ravlic-Gulan J. Femoral neck anteversion: values, development, measurement, common problems. Coll Antropol. 2000 Dec;24(2):521-7.

Sakai T, Sugano N, Ohzono K, Nishii T, Haraguchi K, Yoshikawa H. Femoral anteversion, femoral offset, and abductor lever arm after total hip arthroplasty using a modular femoral neck system. J Orthop Sci. 2002;7(1):62-7.

Unlu MC, Kesmezacar H, Kantarci F, Unlu B, Botanlioglu H. Intraoperative estimation of femoral anteversion in cementless total hip arthroplasty using the lesser trochanter. Arch Orthop Trauma Surg. 2011 Sep;131(9):1317-23.

Unnanuntana A, Toogood P, Hart D, Cooperman D, Grant RE. Evaluation of proximal femoral geometry using digital photographs. J Orthop Res. 2010 Nov;28(11):1399-404.

Hangartner TN. Thresholding technique for accurate analysis of density and geometry in QCT, pQCT and microCT images. J Musculoskelet Neuronal Interact. 2007 Jan-Mar;7(1):9-16.

Rathnayaka K, Sahama T, Schuetz MA, Schmutz B. Effects of CT image segmentation methods on the accuracy of long bone 3D reconstructions. Med Eng Phys. 2011 Mar;33(2):226-33.

Wu G, Siegler S, Allard P, Kirtley C, Leardini A, Rosenbaum D, et al. ISB recommendation on definitions of joint coordinate system of various joints for the reporting of human joint motion--part I: ankle, hip, and spine. International Society of Biomechanics. J Biomech. 2002 Apr;35(4):543-8.

Kingsley PC, Olmsted KL. A study to determine the angle of anteversion of the neck of the femur. J Bone Joint Surg Am. 1948 Jul;30A(3):745-51.

Sugano N, Noble PC, Kamaric E. A comparison of alternative methods of measuring femoral anteversion. J Comput Assist Tomogr. [Comparative Study]. 1998 Jul-Aug;22(4):610-4.

Kim JS, Park TS, Park SB, Kim IY, Kim SI. Measurement of femoral neck anteversion in 3D. Part 2: 3D modelling method. Med Biol Eng Comput.2000 Nov;38(6):610-6.

Sproul RC, Reynolds HM, Lotz JC, Ries MD. Relationship between femoral head size and distance to lesser trochanter. Clin Orthop Relat Res. 2007 Aug;461:122-4.

Orwoll ES, Bliziotes M. Heterogeneity in osteoporosis. Men versus women. Rheum Dis Clin North Am. 1994 Aug;20(3):671-89.

Published
2016-11-29