The boutonniere deformity is a problem that affects the extensor tendons of the finger. The joint near the end of the finger is called the distal IP joint (DIP joint). (Distal means further away.) The proximal IP joint (PIP joint), is the middle joint between the main knuckle and the DIP joint. (Proximal means closer in.) The IP joints of the fingers work like hinge joints when you bend and straighten your hand. A boutonniere deformity occurs when disease or injury causes the PIP joint to become flexed (bent) and the DIP joint is pulled up into too much extension (hyperextension).
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, surgeons 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.
Other conditions that affect the central slip can cause the boutonniere deformity, e.g. 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 may not occur right away. It is the imbalance in the extensor hood that results from the torn tendon that eventually causes the deformity. Because the middle phalanx no longer is pulled by the central slip, the flexor tendon on the other side begins to bend the PIP joint without resistance. The lateral bands begin to slide down along the side of the finger where they continue to straighten the DIP joint. Eventually the finger becomes stiff in this position.
Initially, the finger is painful and swollen around the PIP joint. The PIP joint may not straighten out completely under its own power. The finger can usually be straightened easily with help from the other hand. Eventually, the imbalance leads to the typical shape of the finger with a boutonniere deformity.
If the injury to the central slip results from a simple avulsion (tearing) of the tendon from the bone, splinting of the PIP joint for six weeks should allow the bone to heal and prevent the boutonniere deformity from occurring. The DIP joint is free to move throughout this period and can be exercised to prevent stiffness in the DIP joint. Special splints have been designed that are similar to springs. These splints can be used to gently stretch out a contracture of the PIP joint over several weeks. The spring applies gentle pressure all the time, and the PIP joint slowly straightens. A splint may also be needed to keep the DIP joint from hyperextending. Newer styles are shaped like jewellery rings and are available in stainless steel, sterling silver, or gold. Splinting and a rigorous exercise programme may even work when the condition has been present for some time. Your surgeon will try six weeks of splinting with the spring type splint and exercise to see if the deformity lessens to a tolerable limit before considering surgery. This is desirable before surgery to stretch out a PIP contracture before repairing or reconstructing the extensor hood.
Surgery is required in some cases of boutonniere deformity. Best results occur when the PIP joint is limber, rather than stuck in a bent position. If the PIP joint is stuck in a bent position, surgeons usually wait before doing surgery to see if splinting will help stretch and straighten the PIP joint.
When the deformity is the result of a dislocation of the PIP joint, surgery may be required to repair the damaged structures and prevent the later development of a boutonniere deformity. A pin is usually placed through the PIP joint to fix the joint in place for up to three weeks. Patients wear a splint to protect the joint for another three weeks after surgery.
Soft Tissue Repair
In cases where the balance cannot be restored to a tolerable limit with splinting or by simply pinning the PIP joint, surgery may be required to reconstruct and rebalance the extensor hood. There are numerous types of operations that have been designed to try and rebalance the extensor hood. None is completely successful. Surgery to repair the soft tissues that are contributing to a boutonniere deformity carries a relatively high risk of failure to achieve completely normal functioning of the extensor mechanism of the finger. All of the repair and reconstruction procedures are dependant on a well designed and rigorous exercise program following the surgery. A specialist hand physiotherapist therapist will work closely with you during your recovery.
If past treatments, including surgery, do not stop inflammation or deformity in the joint, finger joint fusion may be recommended. Joint fusion is a procedure that binds the two joint surfaces of the finger together, keeping them from moving. Fusing the two joint surfaces together eases pain, makes the joint stable, and prevents additional joint deformity.
You will wear a splint or brace after surgery. A protective finger splint holds the PIP joint straight and is used for at least three weeks after surgery. Surgeons may apply a dynamic splint to help gradually straighten the PIP joint. Physiotherapy treatments usually start three to six weeks after surgery. You will likely need to attend therapy sessions for three to four months, and you should expect full recovery to take up to six months.