Correction of boutonniere deformity

The boutonniere deformity is characterized by flexion at the proximal interphalangeal (PIP) joint and hyperextension of the distal interphalangeal (DIP) joint.

Boutonniere deformities are caused by pathology at the dorsal PIP joint. Disruption of the central slip of the extensor apparatus caused by trauma or synovitis results in flexion ( Fig. 40.1 ).

The lateral bands migrate volarly and contract, creating an extension force across the DIP joint. The oblique and transverse retinacular ligaments also gradually contract, worsening DIP hyperextension.

Boutonniere deformities can be flexible or fixed. Over time, destruction of the articular cartilage can lead to significant arthrosis of the PIP joint.

The Nalebuff stage is based on the passive correctability of the PIP joint and the condition of the articular cartilage.

• Stage 1: PIP joint synovitis and a slight (10–15 degree), fully correctable extensor lag

• Stage 2: Marked PIP joint flexion (30–45 degrees) that can be fixed or is partially correctable; joint surface intact

• Stage 3: PIP joint fixed flexion contracture and joint erosion

For acute, flexible boutonniere deformities, the patient is splinted with the PIP joint extended and the DIP joint free for 6 weeks. Active and passive DIP range of motion (ROM) exercises are performed hourly to encourage dorsal migration of the lateral bands and to stretch the transverse retinacular ligament. After 6 weeks, the patient is weaned from the splint during the day and performs active PIP flexion exercises. The splint is worn at night for an additional 6 weeks.

For chronic boutonniere deformities, serial casting is used to correct PIP flexion. Full PIP extension is maintained for 6 to 12 weeks and DIP flexion exercises are performed. Operative release of tight collateral ligaments or the volar plate can be performed if full PIP extension cannot be achieved with therapy alone.

Surgery is rarely indicated for boutonniere deformities; they are less functionally debilitating than swan-neck deformities because finger flexion and power grip are maintained. Do not operate on a functional finger.

The goal of surgical correction is to increase extensor force across the PIP joint and decrease extension at the DIP joint. Full passive motion is required before surgery. Joint releases, when indicated, must be performed before tendon rebalancing.

Surgical correction is indicated in patients with flexible, nonarthritic joints who are unresponsive to splinting and have a functional deficit.

Inspect for scars and swelling at the dorsal PIP joint and examine the posture of the finger.

Active and passive ROM are assessed independently at the metacarpophalangeal (MCP), PIP, and DIP joints.

The Elson test evaluates central slip integrity. The PIP joint is held in 90 degrees of flexion and the patient is asked to extend the finger. A patient with an intact central slip will generate force at the PIP joint but will be unable to actively extend the DIP. Conversely, a patient with a central slip injury will be unable to extend the PIP and the force will be transferred to the DIP joint.

The Boyes test is performed by holding the PIP joint extended and asking the patient to flex the DIP. If the extensor mechanism is intact, the patient will be able to flex at the DIP. If the lateral bands are contracted from injury to the extensor tendon, the patient will be unable to flex the DIP.

In rheumatoid arthritis (RA) patients with ulnar drift, PIP motion is assessed with the MCP joint extended with radial and ulnar inclination to assess for intrinsic muscle shortening ( Fig. 40.2 ).

Standard, three-view x-rays are mandatory to evaluate for dislocations, fractures, and articular wear.

Patients with significant arthritis are not candidates for soft-tissue reconstruction and are best treated with arthrodesis or arthroplasty to relieve pain.