Additive manufacturing for paediatric medical devices

Abstract

It should be noted that there is an absence of satisfactory medical devices for children with many types of medical conditions due to the relatively small size of the paediatric medical service market as compared with the adult medical service market, which does not incentivize many companies to focus on the particular characteristics and needs of children (Field et al., (2006). Five to six per cent of healthcare spending is for children despite the fact the children constitute 25 per cent of the overall population (Barbella, 2014). In addition, “the reality of (the medical device companies’) business structures don't allow them to (work on paediatric products) because it's not going to be something that will help their bottom line, and they have to answer to their shareholders” according to Don Lombardi (former Chief Intellectual Property Officer, Boston Children's Hospital, and founder of the Institute for Pediatric Innovation) (Barbella, 2014). The return on investment for a paediatric medical device falls below the profit goals of many medical device manufacturers (Crosse2011). In addition, medical devices are now being used with younger patients than in earlier years. Kurt Vedder (CEO, Fixes 4 Kids Inc.) noted that ‘surgeons are operating earlier in a child's life and because of that there's a need for technology, tools and devices (Barbella, 2014)'. Another limitation to the development of paediatric medical devices is that each child exhibits a different activity level, chemical composition, height, heart rate and blood pressure from his or her peers; in addition, these values will vary in a given child over time (Barbella, 2014). This limitation hinders the development of ‘generic’ medical devices for use over a wide paediatric population. Furthermore, medical device companies may not be able to readily obtain parental consent for a study; such ethical issues are considered a significant challenge to paediatric medical device development. Finally, there is also a perception of higher liability levels associated with paediatric medical devices (Barbella, 2014).

Paediatricians and patient advocates have noted the possibility of adverse outcomes associated with the unavailability of paediatric medical devices (Food & Drug Administration, 2004). Many efforts at this time involve ‘working around’ the absence of an appropriate medical device for children with a repurposed adult medical device. For example, stents for use in the bile duct are repurposed for use in paediatric heart catheterization since no paediatric heart stents are available. Although FDA regulations permit ‘off-label’ or unlabelled uses of medical devices, many such devices do not precisely fit patient needs; for example, bile duct stents are associated with risk of either perforating or blocking the blood vessel undergoing treatment (Shaffer et al., 1998). A new paediatric-specific medical device may be necessary if the workaround is insufficient (e.g. a medical device scaled for paediatric use is unavailable).

Additive manufacturing is a technology that was developed approximately thirty years ago for fabrication of machine tool prototypes (Boland et al., 2007). The term additive manufacturing is used to describe fabrication of three-dimensional structures via selective joining of materials in an additive layer-by-layer manner. Additive manufacturing techniques have recently been used to create patient-specific medical devices with small-scale features. For example, data obtained from magnetic resonance imaging, computed tomography or other imaging techniques may be utilized to create patient-specific implants, prostheses and medical devices. These customized medical devices may possess suitable features, including geometry, size and weight, for diagnosis and/or treatment of a given medical condition. Unlike conventional machining-based processes, medical devices with complex internal geometries (e.g. catheters with interlocking tips) may be generated via additive manufacturing processes (Azari & Nikzad, 2002; Pham & Gault, 1998; Sun et al., 2004; Webb, 2000). It is important to note that additive manufacturing processes can create structures with fewer steps and more quickly than conventional machining-based processes; the product development cycle may be lowered to 10-20% that of traditional methods per Hou and coworkers (Hou et al., 2010; Peltola et al., 2008).

Additive manufacturing can overcome the limitations associated the conventional paediatric medical device manufacturing approaches since it allows for rapid processing of medical devices with patient-specific features and complex geometries at low cost and in low volumes (Field et al., 2006). The prices for many types of additive manufacturing machines have decreased in recent months, and the trend is expected to continue as additive manufacturing patents expire (Arrowsmith, 2013). A company has demonstrated processing of a prosthetic hand for a child with symbrachydactyly for between $3.80 and $5.00 (Arrowsmith, 2013). Additive manufacturing has been recently used to create an implantable customized tracheal splints out of a degradable polycaprolactone powder (Barbella, 2014). Prof. Glenn Green and Prof. Scott Hollister at the University of Michigan obtained computed tomography scans of the respiratory tracts of two paediatric patients and used this information to create splints that matched the patients’ anatomical features (Barbella, 2014). Additive manufacturing is also being widely used to manufacture prosthetic limbs due to the advantages of customization, low cost and distributed manufacturing (Zuniga et al., 2015). It is anticipated that additive manufacturing will play a growing role in manufacturing of medical devices over the coming years.