Boutonniere finger deformity is the result of the rupture of the central band of the extensor tendon in the middle phalanx leading to hyperextension of the metacarpo-phalangeal joint and the distal inter-phalangeal joint and hyperflexion of the proximal inter-phalangeal joint.
Boutonniere finger deformity is most often encountered in the hands of rheumatoid arthritis sufferers. This is the result of joint subluxations and subsequent tendon tears. Other causes include trauma such as that resulting from the mishandling of balls in sports like basket ball and rugby, and following sprains and fractures (not a tendon injury).
Patients suffering from Boutonniere finger deformity will present with hyperextension of the metacarpo-phalangeal joint and the distal inter-phalangeal joint and hyperflexion of the proximal inter-phalangeal joint.This deformity makes it difficult or impossible to actively extend the proximal inter-phalangeal joint actively. Passive extension of the proximal interphalangeal joint may be achieved in early deformities where joints aren’t yet fused. Rule out arthritic pathologies such as R.A.