Other conditions that affect the central slip can cause the boutonniere deformity. For example, prolonged inflammation in the PIP joint from rheumatoid arthritis stretches and eventually ruptures the central slip. A severe burn on the hand can damage the central slip. Another problem affecting the hand, called Dupuytren's contracture, can weaken the central slip and produce the boutonniere deformity.
The boutonniere deformity happens when the extensor tendon attachment to the middle phalanx is injured. This area is called the central slip. This tendon attachment may be injured in many ways. The central slip may simply be damaged when a cut occurs over the back of the middle finger joint (PIP joint). More commonly the central slip tears or pops off its attachment on the bone when the finger is jammed from the end, forcing the PIP joint to bend. When a small amount of bone is pulled off with the tendon, doctors call it an avulsion fracture. The central slip can also be torn when the PIP joint is dislocated and the middle phalanx dislocates towards the palm.
Thu, 2010-10-07 10:39