Goal
The goal of this project was to create an affordable, custom brace for patients with mallet finger injuries.
Background
A mallet finger is when the extensor tendon, on the most distal joint of the finger from the body, is damaged. The damage can be detachment from the bone or severing of the tendon. This results in the patient being unable to extend their finger and can lead to permanent disfigurement and loss of function.
Healthcare options include a combination of physiotherapy and bracing or surgical intervention. Bracing is done to keep the finger in an extended position so that the tendon can heal. Bracing solutions currently given to patient's are a combination of molded plastic and sheets of molded plastic taped to the finger.
3D Scanning
An effective brace needs to be sized correctly to the patients dimensions. To accomplish this a 3D scan of the finger was made with the Qlone phone app and imported into Autodesk Fusion 360.
3D Modeling
First Prototype
Based on the 3D model of the patient's finger, an initial prototype was drafted in Fusion 360. The design was composed of 2 parts. The first part, comprised of two rings connected by cross-bars. The rings acted as an anchor and fit onto the patient's middle phalange. The second part was a solid piece of material angled upwards to hold the distal phalange in an extended position. The angle was decided upon after consultation with the physiotherapist. A prototype was produced using an Anycubic Photon SLA 3D printer.
Second Prototype
During testing, the first prototype suffered a stress failure where the two portions of the design met. When the patient bent their finger a large amount of stress was generated at the middle distal phalangeal joint. The second prototype kept the same design but added a third cross bar between the two anchoring rings at the bottom, helping to distribute any generated loads.
Results
The patient's finger was significantly straightened when compared to before treatment and retained most of the function in their finger.
Future Work
Future designs are in planning allowing for rotation of the joint when force is applied. Check back soon!