Buttonhole Deformity / Boutonniere Deformity
Due to inflammation of the finger’s middle joint capsule, the extensor tendon slips to the flex side. As a result, the middle joint pushes through the resulting tendon gap like a button through a buttonhole. The middle joint will have extreme flexion while the end joint will be hyperextended.
A further cause for buttonhole deformity is an isolated rupture to the extensor tendon at the middle joint of the finger. Surgical correction is possible here if the function of the finger has been affected.
On the whole, the surgery to correct the extensor tendon is not always successful. This is due to the fact that through the stretching and the following shortening of other parts of the extensor tendon, the overall balance of various areas has been significantly damaged.
More on tendon injuries at
Hand Surgery at a Glance