Bone-Ti Alloys Interaction in Hip Arthroplasty of Patients with Diabetes, Dyslipidaemia, and Kidney Dysfunction: Three Case Report and Brief Review

Background and Objectives: Great efforts in orthopaedic surgery have been devoted to the ad-vancement in prosthetics, with a focus on various materials with enhanced mechanical, physical, and chemical properties, geometries of implants, and their surface morphology. A considerable in-terest relates to interfaces with the bone tissues, and their surroundings, e.g., body fluids, building interaction with the living body. Organ dysfunctions effect the quality of bone. The objective of the study is to find interconnections between the underlying conditions of patients, the quality of their bones, and their orthopaedic implants, on different time spans. We refer to femoral stems only. Materials and Methods: We report on three cases, two women (F1 aged over 35, and F2 aged over 80), and one man (M aged over 65), with diabetes, dyslipidaemia, and kidney dysfunction, under-going HA with uncemented Ti-alloy implants. The samples examined were: a segment of a broken Ti-alloy stem (7 years old), biological remnants on it (bone with a metallic layer, 1.75 cm2 and 2.53 g, and soft tissue, 1.50cm2 and 1.098 g), segments of two spare stems, and synthetic plasma enriched with glucose, urea, and cholesterol (according to the biochemistry tests of the respective patients). The stem pieces, 20 x 11 x 6.56 mm3, were immersed in the corresponding synthetic plasma at 38 C and ultrasonicated for 7h. Scanning electron microscopy and energy dispersive X-ray spectroscopy were employed to investigate the Ti-alloy stem samples, and electrochemistry - to adequately explore the plasma left after sonication (50µL/sample) of each sample. Histopatho-logical examination was performed on the soft tissue remnants on the broken stem. Results: EDX spectra have shown that all femoral stem samples are of Ti-6Al-4V, with various additions of C, Fe, Si, Zr, coated with hydroxyapatite. The electrochemistry study shows that the metallic layer on the bone fragment was caused by migration of vanadium during the 6 months since fracture to re-vision for M. That finding agrees with analysis of prosthetic vanadium concentration in se-rum/plasma after 6 months, as recently reported by other authors. Conclusions: The reactivity of the stems in altered synthetic plasma is given by the presence of glucose and urea, whereas choles-terol influences on bone quality only. The histopathological analysis shows severe panniculitis and myositis. Numerous neutrophils intermixed by macrophages, and a few lymphocytes, are present, supporting the abundance of small new capillaries (granulation tissue). Metal migration from the prostheses can occur through the chemical interactions between body fluids with abnor-mal biochemistry and the compounds building the orthopaedic prostheses, having however in mind that chemical corrosion, and wear resulting from friction during usual movements of the body, are competing mechanisms, especially through effects like surface cracks. Even though Ti-alloys are fully biocompatible, diabetes, dyslipidaemia, and renal dysfunction alter the bone-implant interface because of dramatically weakened and frail bones, no matter the age, and sex. Therefore, for those patients with complex conditions, it can be anticipated a shorter lifetime of implants till revision than in healthier ones. A brief review supports our experimental findings.