Proximal Interphalangeal (PIP) joint fracture dislocation is a common sport injury but difficult to treat. Poor treatment of lack of treatment often leads to loss of motion, pain and overall functional decline of the hand. The current literature indicates the treatment of choice is dynamic traction method with early passive movement. There are a variety of reported devices. However, they are cumbersome, difficult to apply, and some are very expensive. The purpose of this study is to evaluate our new design of a dynamic spring distraction device in a cadaveric model of PIP joint fracture dislocation.

Method

A simple spring distraction device was designed that has the ability to unload the unstable joint through a full arc of rotation. This allows early passive motion, hence utilizing the beneficial effects of early motion on articular cartilage remodeling. The compressed spring is used to provide the distracting force. It is housed within a low profile, hollow metal tube. Ten cadaveric models of PIP joint fracture dislocations were created. The proximal K-wire is inserted in the center of the axis of rotation (i.e the cener of the head of the proximal phalanx). The placement of the pin is checked under fluoroscopy. Two distal pins are then inserted parallel to the proximal pins. One is placed at 2.5cm distal to the proximal pin and one at 1cm further distally, into the middle phalanx. A custom made spring is then put inside the hollow tube system. We test various springs with different potential energy. The distracting forces range between 300grams to 1 kilogram on each side of the finger. After placement of the device, the adequate distraction is confirmed on the fluoroscopy. We also test the spring device against various flexion and extension forces by placing different weight on the flexors and extensors.

Results: In our ten PIP joint fracture dislocation models, the device has shown to maintain adequate dynamic distraction throughout the range of motion of the joint.

Conclusion

This new dynamic distraction device is very simple, inexpensive, and effective in the treatment of unstable fracture dislocation of the PIP joint.