How is a type IV swan-neck deformity in rheumatoid arthritis (RA) treated?

Updated: Jun 11, 2021
  • Author: Michael Neumeister, MD, FRCSC, FACS; Chief Editor: Joseph A Molnar, MD, PhD, FACS  more...
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Patients with a type IV deformity have stiff PIP joints and associated radiographic changes consistent with advanced intra-articular disease. These deformities require a salvage-type procedure—namely, arthrodesis or arthroplasty. In deciding which of these procedures to perform, it is important to consider the status of adjacent joints, flexor tendons, and ligaments. It is also important to assess the function of the adjacent fingers. Fusion is particularly useful for the index and middle fingers, because these digits need lateral stability when opposed to the thumb during pinch. Arthroplasty is recommended for the ring and small fingers, where mobility aids grasp. If the MP joints require arthroplasty, PIP joint fusion is recommended, although it has been suggested that arthroplasty can be performed.

Proximal joint fusion involves a curved dorsal skin incision. A longitudinal incision is made through the tendon over the joint, resecting the collateral ligaments. Two Kirschner wires (K-wires) are then passed obliquely across the joint to provide stable fixation, usually at 25° of flexion for the index finger and slightly more for the third digit. Postoperative care consists of cast immobilization for 6-8 weeks.

Arthroplasty can be performed if the surrounding soft tissues are adequate. A dorsal incision is made to expose the extensor mechanism and is split longitudinally. The articular surfaces of the opposing proximal and middle phalanges are removed, and the medullary canals are prepared for the insertion of the implant. The skin is closed with the joint in slight flexion. A palmar incision is then made to release any flexor tendon adhesions. Postoperative care includes splinting the PIP joints in 10° or 20° of flexion and instituting passive and active exercises with a dynamic extension/flexion splint.

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