Dynamic Uniplanar External Fixation
Treatment to reverse the debilitating soft tissue contractures has traditionally been ineffective with splints, which are limited by the ability of the skin to tolerate pressure at the skin-splint interface. Serial casting, another labor intensive option, has the complication of limiting flexion in adjacent joints.
Proximal Interphalangeal Joint Flexion Contracture Treatment
The anatomy of the PIPJ lends itself to rapid and seemingly irreversibly flexion contractures. The flexor tendons are much stronger than the extensor tendons. Also, the surrounding soft tissue such as the volar plate and collateral ligaments tend to contract and scar in a shortened position. Once the joint becomes contracted, skin and neurovascular structures also shorten, making a rapid surgical contracture reversal difficult.
Another cause of joint contracture can be from Dupuytren’s disease, which is a proliferation of abnormal cells and collagen in the palm of the hand, resulting in contracted cords. The goal of treatment regardless of etiology is to provide a modest extension force to stimulate growth of the volar soft tissues. In cases involving Dupuytren’s contracture, targeting and breaking down the specific collagen found in the cord has also been explored.
Proximal Interphalangeal Joint Flexion Contracture
Proximal interphalangeal joint (PIPJ) flexion contractures are a common complication from injuries to that joint or disease processes such as Dupytren contractures. The inability to extend fingers at the PIPJ can be functionally debilitating. Many integral movements of the hand are dependent on the extension of the fingers. Opening the hand wide enough to grasp an object or straightening the hand to slide into a pocket is dependent on the extension of the PIPJ.
The Agee Digit Widget® was designed to apply the force needed to reverse the contractures directly through the skeleton. The extension torque is limited to the PIPJ and respects adjacent joints. There is also an avoidance of skin pressure due to the nature of being an external fixator. The dynamic nature of the device allows active flexion at the PIPJ, encouraging functional use of the hand during treatment. The amount of extension torque can be adjusted with rubber bands, to balance treatment and avoid complications such as joint inflammation.