Microarchitecture of the Radial Head and Its Changes in Aging Matthias Gebauer • Florian Barvencik • Marcus Mumme • Frank Timo Beil • Eik Vettorazzi • Johannes M. Rueger • Klaus Pueschel • Michael Amling Received: 11 February 2009 / Accepted: 2 October 2009 Ó Springer Science+Business Media, LLC 2009 Abstract Fractures of the radial head are common; how- ever, it remains to be determined whether the radial head has to be considered as a typical location for fractures associated with osteoporosis. To investigate whether the human radial head shows structural changes during aging, we analyzed 30 left and 30 right human radial heads taken from 30 indi- viduals. The specimens taken from the left side were ana- lyzed by peripheral quantitative computed tomography (pQCT) and micro-CT. The specimens taken from the right elbow joint were analyzed by radiography and histomor- phometry. In these specimens pQCT revealed a significant decrease of total and cortical bone mineral density (BMD to BMD co ) with aging, regardless of sex. Histomorphome- try revealed a significant reduction of cortical thickness (Ct.Th), bone volume per tissue volume (BV/TV), and tra- becular thickness (Tb.Th) in male and female specimens. In this context, mean BV/TV and mean trabecular number (Tb.N) values were significantly lower and, accordingly, mean trabecular separation (Tb.Sp) was significantly higher in female samples. The presented study demonstrates that the radial head is a skeletal site where different age- and sex- related changes of the bone structure become manifest. These microarchitectural changes might contribute to the patho- genesis of radial head fractures, especially in aged female patients where trabecular parameters (BMD tr and Tb.Sp) change significantly for the worse compared to male patients. Keywords Bone architecture/structure Á Bone density Á Quantitative computed tomography Á Osteoporosis Á Epidemiology Á Aging Fractures of the radial head or neck account for about 1.5– 4% of all fractures and for 26% of all elbow fractures [1, 2]. Radial head fractures are classified according to Mason [3], who introduced three clinical types: type I fractures are fissure fractures or marginal sector fractures without dis- placement, type II fractures are dislocated marginal sector fractures, and type III fractures are comminuted fractures of the whole radial head. Undisplaced fractures usually result in minimal residual deficits independent of treat- ment, whereas displaced fractures have been described as having the risk of an unfavorable outcome [4]. Based on biomechanical and clinical evidence, radial head fractures are caused by a fall on the extended forearm or a direct trauma to the elbow [5]. While it is recognized that the trauma energy and the position of the elbow at the time of injury are important factors in the pathogenesis and severity of radial head fractures, the possible role of Matthias Gebauer, Florian Barvencik and Marcus Mumme contributed equally to this work. M. Gebauer (&) Á F. Barvencik Á M. Mumme Á F. T. Beil Á J. M. Rueger Á M. Amling Department of Trauma, Hand, and Reconstructive Surgery, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany e-mail: mgebauer@uke.uni-hamburg.de M. Gebauer Á F. Barvencik Á M. Mumme Á F. T. Beil Á M. Amling Center for Biomechanics and Skeletal Biology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany E. Vettorazzi Department of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany K. Pueschel Institute of Forensic Medicine, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany 123 Calcif Tissue Int DOI 10.1007/s00223-009-9304-0