Femoral head density on CT scans of patients following hip fracture fixation by expandable proximal peg or dynamic screw Ely L. Steinberg a, *, Amir Sternheim a , Arye Blachar b a Department of Orthopedic Surgery ‘‘B’’, Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, 6 Weizmann St., Tel-Aviv 64239, Israel b Department of Radiology, Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel Introduction Hip fractures with high morbidity and mortality rates are common among the elderly. More than 250,000 hip fractures occur annually in the United States alone, resulting in 30% of all orthopedic hospital admissions, and consuming 1% of the total health-care expenditure. 11 The number of hip fracture patients is projected to double by the year 2050, and their mean age is projected to dramatically increase with the graying of the population worldwide. 13 The incidence of comminuted fractures among the total fractures of the proximal femoral area is increasing. Adequate fixation of the proximal fragment depends considerably on the quality of cancellous bone in the femoral head and neck. 8,14,26 Diminished bone stock in osteoporotic patients who harbor unstable fractures increases the risk of implant failure, regardless of the device that is used. 3,10 Sliding nail plate fixation, the preferred treatment for intertrochanteric fractures, has high failure rates in osteoporotic femora, mainly due to upward penetration and shortening. 3,9 The intramedullary hip nail may have some advantage over the sliding nail plate because of decreased bending strain that is achieved by moving the shaft fixation medially and decreasing the lever arm on the implant. Such a hip nail may also offer a biological advantage of combining a closed technique with limited periosteal disruption. Bone density measurements around implants have been widely used to assess recipient site quality and its adaptation to the new implant. Most of those studies used dual energy X-ray absorpti- ometry (DXA) 1,2,6,18 or computed tomography (CT). 7,16,20,21 How- ever, DXA absorptiometry provides two-dimensional analysis and not a complete circular analysis. 18 CT is currently a common clinical method for evaluating bone density and bone mineral density, 12,17,19 enabling accurate assessment of the implant incorporation from all sides. Most of the studies using CT for implant assessment were performed after joint replacement surgery or in dentistry for dental implants evaluation. 24,25 To the best of our knowledge, there are no reports on the use of CT scans for evaluating fracture fixation. The expandable proximal hip nail system 22 is comprised of a nail and a peg that are expanded after positioning in the femoral shaft and head (Fig. 1). The expandable peg inserted into the femoral head during hip nailing surgery was tested to evaluate its influence on the femoral bone matrix at insertion and after expansion. 5 DXA and microradiography demonstrated increased peri-implant bone density following peg expansion, without significant increase in intraosseous pressure. 5 Injury, Int. J. Care Injured xxx (2010) xxx–xxx ARTICLE INFO Article history: Accepted 11 February 2010 Keywords: Hip fractures Bone density Expandable nail Dynamic hip screw Computed tomography ABSTRACT Computed tomography (CT) is currently considered to be an accurate method for evaluating bone density. We evaluated the CT measurements of bone density using the Hounsfield units (HUs) in 23 patients who had been operated in the past for an extra-capsular hip fracture. Twelve patients were treated with a dynamic hip screw and 11 with a proximal femoral expandable hip nail. All the CTs had been performed for non-orthopedic purposes. Bone density with a region of interest (ROI) could be assessed for both hips. We compared the bone density between the operated versus the non-operated sides as well as between the two surgical groups. Bone density was higher in the hip peg (the femoral component of the expandable nail) side 262.5 (range, 169–351) HU, compared to the opposite non-operated side and to the hip screw group 194 (range, 99–283) HU. The hip screw side had decreased bone density compared to the opposite non- operated side. We were able to define a density index and a difference index: both were higher in the hip peg group. These findings persisted over time. It would be interesting to speculate that increased bone density around an expandable peg provides better fracture stabilization and probably faster healing than a dynamic hip screw. ß 2010 Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: +972 3 6974727; fax: +972 3 6974546. E-mail addresses: steinberge@tasmc.health.gov.il, eli_st@netvision.net.il (E.L. Steinberg). G Model JINJ-4204; No. of Pages 5 Please cite this article in press as: Steinberg EL, et al. Femoral head density on CT scans of patients following hip fracture fixation by expandable proximal peg or dynamic screw. Injury (2010), doi:10.1016/j.injury.2010.02.012 Contents lists available at ScienceDirect Injury journal homepage: www.elsevier.com/locate/injury 0020–1383/$ – see front matter ß 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.injury.2010.02.012