15502-m-pleumeekers

INTRODUCTION Surgical reconstruction with autologous cartilage or alloplastic implants is the only existing treatment for auricular defects. The current gold-standard technique - autologous ear reconstruction [120] - is a multi-staged time-consuming procedure [9, 121], that ranks among the most complicated of reconstructive surgeries [122]. In short, autologous cartilage is harvested from the ribs, shaped appropriately and implanted subcutaneously. Ear cartilage tissue-engineering (TE) is a potential alternative that endeavors to circumvent the resulting donor-site morbidity by engineering rather than harvesting cartilage. [58, 123-137] Ideally tissue-engineered ear cartilage should possess similar mechanical properties to the native tissue in order to withstand daily load (e.g. wearing spectacles, helmets, ear phones, etc.) and without causing discomfort. [138] Selecting autologous material for ear cartilage surgical reconstruction is difficult, where donations come from the nasal septum, auricle and rib. Whether the graft qualifies mechanically for surgical implantation is usually made from simple palpation. Mechanical properties of hyaline (e.g. nasoseptal, costal, articular cartilage) and fibrocartilage (e.g. intervertebral disk) have been extensively documented. [139-141] The structure-function relationship linking composition and architecture to mechanical competency has been established for these cartilage subtypes. [140, 142] The mechanical properties of ear cartilage are, however, sparsely investigated [143], and limited data are available for human cartilage. [24, 138] Unlike hyaline and fibrocartilage, ear cartilage contains large amounts of elastin fibers. Those fibers play a mechanical role in tissues such as arteries and skin [144, 145], therefore the mechanical properties of ear cartilage are expected to vary from other cartilage types [138]. Mechanical evaluation has often been overlooked in ear cartilage TE attempts. Many authors [58, 123, 125-137] report a qualitative mechanical assessment, while a few publications report quantitative data but without comparison to human ear cartilage [146-150]. Indentation has been shown previously to be a good and sensitive first approximation for direct comparison between native and tissue-engineered constructs. [151] In light of this, the aim of this work is to establish a mechanical characterization of native human ear cartilage in order to set a benchmark against which to evaluate TE constructs. Mechanical and biochemical properties of fresh ear cartilage are determined and compared to hyaline nasoseptal cartilage. Additionally spatial variation in mechanical properties, the influence of patient gender and age, and correlations between mechanical properties and biochemical composition are investigated. 29 EAR CARTILAGE CHARACTERISTICS 2