Patients who have this deformity can not straighten the middle joint of the finger. Flattening the finger is provided with a very complex mechanism. Extension of whole finger can be made by three tendons; the bigger in the middle extends two parts next to the palm, while the other two on both side of the middle one extend the finger part where the nail is located. Closed or open injuries which affect the middle extensor tendon may result in buttonhole(Boutonierre) deformity.
The first approach in closed injuries should be physiotherapy(figure 1). If appropriate splinting under physiotherapist observation fails surgical intervention is needed. Most of the time reinserting the middle tendon to its original place is not possible. There are numerous methods described for correction. In this case, lateral two tendons are utilized to correct the position and function. But again, long term physiotherapy is needed after surgery.