Boutonniere Deformity

Fingers may be small, but they play an essential role in life. Each finger has its systematic function permitting the ability for flexion, extension, and range of motion for everyday activity. Each finger, except the thumb, is comprised of three bones and three joints. The two joints affected by a boutonniere deformity are the proximal interphalangeal joint (PIP) in the middle of the finger and the distal interphalangeal joint (DIP) at the fingertip.

Ligaments connect bone to bone, and tendons connect muscle to bone. Tendons run along the top and side of each finger. These tendons are responsible for the movement and the straightening of the finger. Tendons are classified as either flexors or extensors, allowing the finger to either bend or straighten out. The tendon that is present on the top of the finger, known as the extensor, is responsible for finger straightening.

In the case of a boutonniere deformity, the extensor tendon on top of the PIP (known as the central slip) is torn or injured. Subsequently, the middle joint will push its way through the tear, causing the finger to bend – this disruption of the tendon will cause the DIP to have an opposite effect – hyperextension. The name boutonniere is derived from “buttonhole” because the tear through the tendon appears similar to a buttonhole.

Causes

Boutonnière deformity can have several different causes ranging from the onset of chronic conditions such as rheumatoid arthritis to acute trauma to the finger.

Symptoms

The classic sign of this deformity presents at the flexed middle joint and cannot be straightened while the joint at the fingertip is extended. The signs and symptoms of a boutonnière deformity can present gradually or more acutely depending on its cause. Patients with rheumatoid arthritis will have a more insidious onset of this deformity. Patients who had a trauma or injury to the finger may develop this deformity within a week to 3 weeks.

At the site of the deformity, patients can also present with pain, swelling, and stiffness.

Treatment

The goal of treatment is to restore the ability of the finger to completely straighten while also achieving an appropriate finger range of motion. The treatment for a boutonniere deformity can be either operative or nonoperative. It is recommended that it be treated early in its onset to yield the best results of retaining the full range of motion of the finger. If a boutonniere finger remains untreated for an extended time, it will become increasingly difficult to correct and provide symptom relief.

Non-operative Options

Nonoperative options are most effective when the deformity is addressed early. A finger splint is the recommended nonoperative option for treating boutonniere deformity to keep the finger straight. The splint keeps the ends of the torn/injured tendon together and prevents it from separating as it heals. It is a very rigorous course of immobilization to allow the tendon to heal in proper alignment. The length of time wearing the splint can differ based on the patient’s age.

Usually, we require approximately six weeks for a young patient to wear the splint, whereas, for an elderly patient, it is usually three months.

In addition to splinting, patients will control pain and swelling with non-steriodal anti-inflammatories and over the counter pain medication.

Occupational therapy with range of motion exercises can also be advantageous for patients after a formal course of non-operative or operative treatments.

Surgical Options

While the conservative treatment option is preferred for a boutonniere deformity, surgery is an alternative for certain severe cases, including when the deformity results from the failure of conservative treatment, the tendon is severed, or a large bone fragment is displaced from its normal position. The surgery is minimally invasive and allows for visualization and repair of the affected tendon.