A 3-Dimensional Printed Dynamic External Fixator for the Treatment of Proximal Interphalangeal Fracture-Dislocations: A Biomechanical Study

Abstract

This study evaluated the efficacy of a 3-dimensional printed dynamic external fixator for treating proximal interphalangeal (PIP) fracture-dislocations. The null hypothesis was that there would be no difference in maintaining PIP joint reduction between a 3-dimensional printed dynamic external fixator (3DPDEF) and the pins and rubbers traction system (PRTS). Ten cadaveric fingers underwent an oblique osteotomy at the base of the middle phalanx, recreating an unstable dorsal PIP fracture-dislocation. The percentages of compromised articular surface and middle phalanx dorsal displacement were measured. Both fixators were randomly placed on each digit and underwent 1,400 flexion-extension cycles. Efficacy, determined by joint reduction and maintenance of dorsal translation correction, was assessed using fluoroscopy before and after the cycles. The mean compromised articular surface was 50.8%. After osteotomy, PIP joint subluxation occurred at 37.8° flexion. Dorsal translation after osteotomies was 2.8 mm. After applying the 3DPDEF and the PRTS, it was 0 mm and 0.1 mm, respectively. During the cycles, all the joints remained stable and reduced. Dorsal displacement after cycles was-0.1 mm for the 3DPDEF and 0 mm for the PRTS. The mean translation difference between both fixators was 0.1 and 0 mm before and after the cycles. The translation differences before and after the cycles were 0.1 mm for both dynamic fixators. The 3DPDEF is a suitable option for PIP fracture-dislocations, providing stability comparable to that of the PRTS while offering benefits, such as easy placement, controlled distraction, and clear visualization of the articular surface. This external fixator, characterized by its efficacy, low cost, and simplicity of application, broadens the options available to address PIP fracture-dislocations.