ORIGINAL COMMUNICATION Bone Mineral Density of Human Ear Ossicles: An Assessment of Structure in Relation to Function C. MORRIS, B. KRAMER ,* AND E. F. HUTCHINSON School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand Johannesburg, South Africa Human ear ossicles are essential for normal sound conduction from the exter- nal environment to the inner ear. These bones are subjected to high biome- chanical loads due to the sustained vibrations which occur with reception of sound. It is expected that the bones would undergo a significant amount of remodeling and change in bone mineral density during the lifespan of an indi- vidual. Therefore, the aim of the study was to evaluate the possible changes in bone mineral density of regions of the ossicular chain during postnatal life. Forty four left and 36 right sets of human ear ossicles, ranging from a sub- adult age group to a mature adult age group, were sourced from the School of Anatomical Sciences, University of Witwatersrand. The ear ossicles were scanned using a micro-focus CT X-ray. A three-dimensional reconstruction of each ossicle was created from the CT scan. Bone mineral density was then determined at specific sites on the ossicles. There was no statistically signifi- cant variation found in the bone mineral density in relation to the age of the specimens. However, the handle of the malleus, the incudo-stapedial joint and the insertion site for the tendon of stapedius had lower bone mineral densities when compared to adjacent articulation and nonattachment sites on the ossic- ular chain. This is possibly due to biomechanical stress in response to sound conduction rather than ageing. Lower bone mineral density may be indicative of regions that experience the highest biomechanical force, thus, resulting in increased remodeling. Clin. Anat. 00:000–000, 2018. V C 2018 Wiley Periodicals, Inc. Key words: ear ossicles; bone density; biophysics; function INTRODUCTION Human ear ossicles are responsible for the conduc- tion of sound from the tympanic membrane to the inner ear and have the ability to maintain energy which occurs during sound transmission (Goode et al., 1994; Drake et al., 2015). This energy loss occurs when sound waves are transmitted from the air which is of low resistance at the opening to the external acoustic meatus, to the cochlear fluid of the inner ear, which is of higher resistance (Goode et al., 1994). The ear ossicles, the malleus, incus and stapes, ossify early in life and achieve their final size in post- natal life (Duboeuf et al., 2015). They are said to undergo little remodeling (Marotti et al., 1998; Chen et al., 2008; Duboeuf et al., 2015; Saha et al., 2017) throughout the lifetime of the individual. However, as the ear ossicles are constantly exposed to and respond to external, as well as self-generated sound, it is possible that certain regions within the ossicular chain undergo some remodeling in response to their biomechanical function (Hill and Orth, 1998). Associated with the ossicles are ligaments and ten- dons, which may have a biomechanical influence on the remodeling of the bone as occurs at other sites in the body (Mavropoulos et al., 2005; Ruffoni et al., *Correspondence to: B. Kramer, School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2191, Johannesburg, South Africa. E- mail: beverley.kramer@wits.ac.za Received 22 March 2018; Revised 11 June 2018; Accepted 11 June 2018 Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/ca.23231 V V C 2018 Wiley Periodicals, Inc. Clinical Anatomy 00:00–00 (2018)