Orthotic materials for distal radius fracture immobilisation: from conventional casting to additively manufactured thermoplastics

Distal radius fractures (DRF) represent one of the most globally prevalent orthopaedic injuries, accounting for roughly 25 and 18% of all paediatric and geriatric fractures respectively. Combined ageing global populations and ever-increasing DRF rates, effective, patient-centred immobilisation strategies are becoming increasing critical. Despite the prevalence of DRF, there is currently no consensus regarding the optimal treatment or duration thereof, with approximately 50% of DRF cases treated using a conservative approach of casting as opposed to a surgical intervention. This review examines the evolution of DRF immobilisation materials from conventional plaster of Paris (PoP)-based systems to more modern additively manufactured (AM)-systems. Conventional approaches utilise PoP or fibreglass composites and though clinically established, display significant limitations such as risk of thermal injury, infection, applicator-dependent quality variance, radio-opacity and patient discomfort. The poor radiopacity of PoP may lead to improper fracture visualisation which may necessitate increased radiation exposure or removal of the cast for improved imaging which may in turn affect the alignment of the fracture. AM, particularly MultiJet Fusion (MJF), represents an emerging and promising alternative that aims to address many of the limitations of conventional systems. Orthoses produced via MJF offer patient-specific geometry, lightweight materials, standardised mechanical properties and excellent radio transparency. There remain, however, critical questions regarding this technology such as material degradation and clinical validation requirements.