Ankle distractor

Abstract

Ankle osteoarthritis (AOA) or degenerative joint disease (DJD ) of the ankle, is a progressive condition characteristic by the thinning of cartilage between the tibia and talus bone. Eventually, this leads to complete ankle joint loss. When looking at surgical treatments, joint sacrificing treatments are the golden standard. Young active people with end-stage AOA find these treatments scary and often want to preserve their joint and ankle motion as long as possible. Therefore, they are postponing these surgical treatments and retain the painful symptoms that accompany AOA.

It is believed that ankle distraction arthroplasty is an alternative, joint sparing treatment. This technique uses an external frame to mechanically unload the ankle joint to support the regenerative capacity of the body to restore cartilage. This frame is fixed to pins in the tibia and talus. The current devices limit joint movements and restrict the surgeon in their pin placement, which results in a painful stiff joint during the treatment period. Furthermore, these devices do not always fit the patient properly. Therefore, the goal is to develop a personalized hinged ankle distractor that allows for ankle movement. This will be a new alternative treatment for young active people with end-stage AOA.

The developed ankle distractor is an external fixator that will be adjusted to the placement of the pins, allowing the orthopaedic surgeon for better pin placement. The pins are placed using a drilling and alignment guide. After this surgery, a CT-scan is made to determine the pin placement and the rotation axis of the patient which are both incorporated within the device. A combination of the distraction device and tibia and talus clamps will be placed at each side of the lower leg to allow for symmetrical distraction. This design results in semi-personalized distraction device that allows for walking with optimized patient comfort while maintaining a partially reusable system.