# 3D Printed Antibacterial Prostheses
## 1 Introduction  
By the year 2050, an estimated 3.6 million persons will be living with amputations within the United States [1]. In the fiscal year 2016, 22% (\(n\) = 20,158) of US veterans who received amputation care at Veterans Affairs (VA) medical facilities had experienced an upper limb amputation [2]. Finger amputations are the most common amputations of upper limbs. Finger amputations influence hand function, general functioning, and quality of life [3]. Despite advances in upper limb prostheses, there is a high rate of user abandonment [4]. Up to 52% of upper limb amputees reject or abandon their prosthesis [2]. Fitting a patient with a prosthesis within 4 weeks after amputation will increase the likelihood of acceptance of the device [5]. This time is known as the 'golden period' of upper extremity prosthetic rehabilitation and may be the most vital factor in a patient's acceptance of the prosthesis [6]. During this period, contractures, muscle atrophy, and infections are common risk factors that can affect prosthesis use and overall function. The use of transitional prostheses decreases the burden on the contralateral limb, increases function by offering an additional grasp with bimanual tasks, assists in body symmetry, and improves self-image [7]. It has been reported that the use ofan immediate post-operative functional prosthesis (i.e., a transitional prosthesis) can also improve the range of motion and strength of the affected hand [8]. However, these functional transitional devices are often made by hand, requiring long construction times and highly skilled technicians to manufacture them [8; 9]. Furthermore, patients using socket-based prostheses face multiple skin disorders and are susceptible to bacterial and fungal infections [10]. These skin disorders have a significant detrimental impact in the function of activities of daily living and quality of life of patients who have experienced limb loss [4]. Previous investigations [11; 12] have shown that copper compounds have a high potential for use in the development of low-cost medical devices with powerful antibacterial properties. These positive characteristics and the high environmental safety of copper makes it capable of replacing silver and other antimicrobial compounds in the development of a wide range of medical devices [11]. Furthermore, a previous investigation reported side effects after using compounds with silver, including local skin irritation, discoloration, or staining, which are harmless and usually reversible [13]. Copper ions function by altering proteins and inhibiting their biological activity, membrane lipid peroxidation, and plasma membrane permeabilization [14]. Copper has also been found to improve the healing process of wounds, as it plays a key role in the enhancement of angiogenesis via the induction of vascular endothelial growth factor, which upregulates the activity of copper-dependent enzymes, cell proliferation and reepithelialization [15]. Specifically, the addition of copper nanoparticles to polymers has been shown to provide strong antimicrobial properties, producing novel biocide materials and allowing the development of a broad range of polymer nanocomposites with a high release of metal ions facilitating the antimicrobial properties [12]. It has been suggested [12] that the addition of copper nanoparticles to polymers and the resulting antimicrobial properties have promising applications in the development of medical devices associated with bacterial development, such as socket-based prostheses, among many others. Recent technological advances in additive manufacturing (i.e., 3D printing) [16] and a new antimicrobial 3D printing filament offer the unique possibility of manufacturing low-cost, customized, and antibacterial upper-limb 3D printed prostheses [16; 17; 18]. The development and effectiveness of manufacturing upper limb prostheses using antimicrobial filaments, however, has not been tested [12].