Background
Current procedures for repairing damage to the articular cartilage in the ankle are not satisfying patient needs and have a minimum rehabilitation time of 4 months. The Chondro project aims to develop an all-in-one polyclinical procedure where diagnosis, treatment and rehabilitation can be performed in one session reducing the rehabilitation time greatly.

Methods
This project aims to develop a flexible steerable needle used in the treatment of the damaged cartilage. The needle will have to apply a two-component hydrogel to the lesion. The device is designed at 5mm diameter with the aim to downscale this to 3mm in the future. The bending radius of the device needs to be at least 16mm at the 3mm scale. These and other requirements were tested in several setups and a pilot study with 15 participants.

Results
Several materials were used to produce different prototype. The best performing prototype was successfully used in the pilot study. The best performing prototype was produced with NinjaFlex and had a bending radius of 25mm at 5mm scale, bucking strength of 3.2N, rotational stiffness of 5.8 μNm/deg and was able to reach the target areas with a mean absolute distance to the centre of the target of 1.5mm.

Conclusion
The designed device is highly precise, relatively stiff in axial direction and could certainly be used to successfully perform the procedure. Rotational stiffness should however be improved. Stiffer material could be used in the future after adaptations have been made to the geometry of the actuator