A Sensor System to Measure Force Applications of a Brace for Pectus carinatum

Abstract

Pectus carinatum (PC) presents itself as a protrusion on the chest wall of adolescent individuals. Current treatment for PC is performed with a Pectus carinatum orthosis (PCO) that applies a compressive force to the protrusion. While this treatment is accepted, the magnitude of compressive forces applied remains unknown leading to excessive or deficient compression. Although the need for this quantitative data is recognized, no studies reporting the data or methods are available. The purpose of this study was to design an accurate force measurement system (FMS) that could be incorporated into a PCO with minimal bulk. Components of the FMS were three-dimensional (3D)-printed and incorporated into an existing PCO design. The FMS was calibrated using a custom indenter that applied forces to the FMS in a controlled manner. Evaluation of the FMS on five human participants was also performed. A reliability measure of the FMS was calculated for analysis. The FMS was implemented into the PCO and able to withstand the applied forces. The calibration revealed an increase in load cell error with increased magnitude of applied force (mean error [SD] = 5.59 N [6.48 N]). Participants recruited to evaluate the FMS demonstrated reliable forces (R = 96%) with smaller standard deviations than those during the calibration. The FMS was shown capable of measuring PCO forces but requires further testing and improvement. This system is the foundational component in a wireless, minimalistic sensor system to provide real time force feedback to both the clinician and patient.

Assessment and treatment of pectus deformities: a review of reverse engineering and 3D printing techniques

“…Finally in Bugajski et al (2019), for the realization of a pressure sensor housing to be integrated in a compression bar, the authors evaluated that the yield strength of the material was sufficient to withstand the compression and bending loads to which the bar is subjected, choosing for this purpose ABS as a compatible material. Carfagni et al (2018) realized the VB in biocompatible silicone realizing the mold exploiting the FDM technology, as no properties of biocompatibility, sterilizability and resistance are required.…”

“…On the other hand, for the fabrication of templates to bend corrective thoracic bars in a controlled and planned manner, the requirement for biocompatibility and sterilizability of materials is not mandatory, so several studies used PLA material for template fabrication (Lin et al, 2018;Huang et al, 2019;Bellia-Munzon et al, 2020;Gaspar Pérez et al, 2021). Finally in Bugajski et al (2019), for the realization of a pressure sensor housing to be integrated in a compression bar, the authors evaluated that the yield strength of the material was sufficient to withstand the compression and bending loads to which the bar is subjected, choosing for this purpose ABS as a compatible material. Carfagni et al (2018) realized the VB in biocompatible silicone realizing the mold exploiting the FDM technology, as no properties of biocompatibility, sterilizability and resistance are required.…”

“…In Bugajski et al (2019), o monitor the corrective treatment of the PC with brace, AM was used to equip the brace with sensors able to evaluate the applied forces.…”