Impact of Bone Density on Distal Radius Fracture Patterns and Comparison between Five Different Fracture Classifications *†C. A. Lill, *J. Goldhahn, *A. Albrecht, ‡F. Eckstein, §C. Gatzka, and *E. Schneider *AO Research Institute, Davos, Switzerland, †Department of Orthopaedic Surgery, University of Heidelberg, Heidelberg, Germany, ‡Musculoskeletal Research Group, Institute of Anatomy, Ludwig-Maximilians-Universität München, Munich, Germany, and §Department of Trauma and Reconstructive Surgery, University of Hamburg, Hamburg, Germany Objective: To investigate the impact of bone mineral density (BMD) and bone geometry on failure loads and fracture pat- terns of the distal radius and to compare 5 different fracture classifications. Design: Biomechanical and radiologic in vitro study. Setting: Research laboratory. Main Outcome Measurements: A total of 118 intact human forearms from elderly donors were examined by means of con- ventional radiography and peripheral quantitative computed to- mography (PQCT) to determine BMD and geometry. The fore- arms were subjected to a standardized biomechanical test simu- lating a fall on the outstretched hand. The distal radius fractures were classified from x-rays using the AO (33), Cooney (9), Fernandez (15), Frykman (17), and Melone (31) classifications. The grading was repeated after preparation and direct visual inspection of the fracture site and was correlated with radio- graphic results. Fracture patterns also were correlated with BMD and geometry. Results: Correlations between bone properties and fracture pat- terns (r  0.09–0.70) suggested an increase in the severity of fractures with decreasing bone quality. The highest correlation between failure load and bone properties was found for the cortical area (r  0.70) and trabecular density (r  0.60). Good correlations between radiographic and direct visual classification were obtained for the Cooney (9) (r  0.70), the AO (33) (r  0.68), and the Fernandez (15) (r  0.65) clas- sifications. Smaller values were found for the Frykman (17) (r  0.44) and the Melone (31) (r  0.27) classifications. Conclusions: With increasing osteopenia, the load to failure decreases, and the severity of fractures increases. Fracture pat- terns in this patient population can be adequately graded with the AO (33) and Cooney (9) classifications. The severity of distal radius fractures tends to be underestimated by conven- tional x-ray examination, which needs to be taken into account when a fracture treatment plan is selected. Key Words: Radius fracture, Classification, BMD, Mechani- cal testing, Bone geometry. Most injuries of the wrist occur due to falls on the outstretched hand. When the hand strikes the ground, a vertical force with variable lateral, dorsal, and axial com- ponents is transmitted by the carpal bones to the distal end of the radius and commonly results in a fracture of the distal radius (7,39). Besides bone mineral density (BMD), the geometry of bone and its mechanical loading conditions are important factors determining fracture risk (3,4,12). When exam- ining the relationship between Colles’ fractures and BMD, most studies found BMD to be lower at the time of injury (10,12,19,22,43); others found it to be normal compared with controls (36). Osteopenia also seems to promote secondary malalignment of comminuted thin cortical walls and crushed porotic cancellous bone in distal radius fractures (10), although Milliez et al (32) observed no correlation with metaphyseal comminution and the degree of displacement. The influence of bone quality and geometry on fracture patterns in the distal radius has been investigated in patients (44) but not yet in a controlled in vitro study. Fracture types and associated injuries depend on the mechanism of trauma, on the amount of energy involved, and on the bone quality. A review of the literature of distal radius fractures yielded more than 10 different classification systems (14,37). Fractures are commonly described by terms that either refer to an author who introduced the description of the fracture or describe the particular fracture type or mechanism of injury. Clinical experience shows that existing fracture classifications are not able to represent every possible injury of the distal radius (eg, comminution and displacement due to osteoporotic fractures) (39). It is also unclear whether Accepted December 3, 2002. Address correspondence and reprint requests to Dr. C. A. Lill, Department of Orthopaedic Surgery, University of Heidelberg, Schlierbacher Landstrasses 200a, D-69118 Heidelberg, Germany; E-mail: christoph.lill@ao.asif.ch No financial support was received for this project. The authors have received nothing of value. This article does not contain information about medical devices. Journal of Orthopaedic Trauma Vol. 17, No. 4, pp. 271–278 © 2003 Lippincott Williams & Wilkins, Inc., Philadelphia 271